Zigzag nanoribbons of two-dimensional silicene-like crystals: magnetic, topological and thermoelectric properties.

PubMed

Wierzbicki, Michał; Barnaś, Józef; Swirkowicz, Renata

2015-12-09

The effects of electron-electron and spin-orbit interactions on the ground-state magnetic configuration and on the corresponding thermoelectric and spin thermoelectric properties in zigzag nanoribbons of two-dimensional hexagonal crystals are analysed theoretically. The thermoelectric properties of quasi-stable magnetic states are also considered. Of particular interest is the influence of Coulomb and spin-orbit interactions on the topological edge states and on the transition between the topological insulator and conventional gap insulator states. It is shown that the interplay of both interactions also has a significant impact on the transport and thermoelectric characteristics of the nanoribbons. The spin-orbit interaction also determines the in-plane magnetic easy axis. The thermoelectric properties of nanoribbons with in-plane magnetic moments are compared to those of nanoribbons with edge magnetic moments oriented perpendicularly to their plane. Nanoribbons with ferromagnetic alignment of the edge moments are shown to reveal spin thermoelectricity in addition to the conventional one.

Multi-Quasiparticle Gamma-Band Structure in Neutron-Deficient Ce and Nd Isotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheikh, Javid; Bhat, G. H.; Palit, R.

2009-01-01

The newly developed multi-quasiparticle triaxial projected shell-model approach is employed to study the high-spin band structures in neutron-deficient even-even Ce and Nd isotopes. It is observed that gamma bands are built on each intrinsic configuration of the triaxial mean-field deformation. Due to the fact that a triaxial configuration is a superposition of several K states, the projection from these states results in several low-lying bands originating from the same intrinsic configuration. This generalizes the well-known concept of the surface gamma oscillation in deformed nuclei based on the ground state to gamma bands built on multi-quasiparticle configurations. This new feature providesmore » an alternative explanation on the observation of two I=10 aligning states in ^{134}Ce and both exhibiting a neutron character.« less

Tilted Thick-Disk Accretion onto a Kerr Black Hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fragile, P C; Anninos, P

2003-12-12

We present the first results from fully general relativistic numerical studies of thick-disk accretion onto a rapidly-rotating (Kerr) black hole with a spin axis that is tilted (not aligned) with the angular momentum vector of the disk. We initialize the problem with the solution for an aligned, constant angular momentum, accreting thick disk around a black hole with spin a/M = J/M{sup 2} = +0.9 (prograde disk). The black hole is then instantaneously tilted, through a change in the metric, by an angle {beta}{sub 0}. In this Letter we report results with {beta}{sub 0} = 0, 15, and 30{sup o}.more » The disk is allowed to respond to the Lense-Thirring precession of the tilted black hole. We find that the disk settles into a quasi-static, twisted, warped configuration with Lense-Thirring precession dominating out to a radius analogous to the Bardeen-Petterson transition in tilted Keplerian disks.« less

Density functional study of intramolecular ferromagnetic interaction through m-phenylene coupling unit (I): UBLYP, UB3LYP, and UHF calculations

NASA Astrophysics Data System (ADS)

Mitani, Masaki; Mori, Hiroki; Takano, Yu; Yamaki, Daisuke; Yoshioka, Yasunori; Yamaguchi, Kizashi

2000-09-01

Polyradicals comprised of m-phenylene-bridged organic radicals are well known as building blocks of organic ferromagnets, in which radical groups are connected with each other at the meta position in the benzene ring, and the parallel-spin configurations between radical sites are more stabilized than the antiparallel ones. Topological rules for spin alignments enable us to design organic high-spin dendrimers and polymers with the ferromagnetic ground states by linking various radical species through an m-phenylene unit. However, no systematic ab initio treatment of such spin dendrimers and magnetic polymers has been reported until now, though experimental studies on these materials have been performed extensively in the past ten years. As a first step to examine the possibilities of ferromagnetic dendrimers and polymers constructed of m-phenylene units with organic radicals, we report density functional and molecular orbital calculations of six m-phenylene biradical units with radical substituents and polycarbenes linked with an m-phenylene-type network. The relative stability between the spin states and spin density population are estimated by BLYP or B3LYP and Hartree-Fock calculations in order to clarify their utility for constructions of large spin denderimers and periodic magnetic polymers, which are final targets in this series of papers. It is shown that neutral polyradicals with an m-phenylene bridge are predicted as high-spin ground-state molecules by the computations, while m-phenylene-bridged ion-radical species formed by doping may have the low-spin ground states if zwitterionic configurations play significant roles to stabilize low-spin states. Ab initio computations also show an important role of conformations of polyradicals for stabilization of their high-spin states. The computational results are applied to molecular design of high-spin dendrimers and polymers. Implications of them are also discussed in relation to recent experimental results for high-spin organic molecules.

Photoresist thin-film effects on alignment process capability

NASA Astrophysics Data System (ADS)

Flores, Gary E.; Flack, Warren W.

1993-08-01

Two photoresists were selected for alignment characterization based on their dissimilar coating properties and observed differences on alignment capability. The materials are Dynachem OFPR-800 and Shipley System 8. Both photoresists were examined on two challenging alignment levels in a submicron CMOS process, a nitride level and a planarized second level metal. An Ultratech Stepper model 1500 which features a darkfield alignment system with a broadband green light for alignment signal detection was used for this project. Initially, statistically designed linear screening experiments were performed to examine six process factors for each photoresist: viscosity, spin acceleration, spin speed, spin time, softbake time, and softbake temperature. Using the results derived from the screening experiments, a more thorough examination of the statistically significant process factors was performed. A full quadratic experimental design was conducted to examine viscosity, spin speed, and spin time coating properties on alignment. This included a characterization of both intra and inter wafer alignment control and alignment process capability. Insight to the different alignment behavior is analyzed in terms of photoresist material properties and the physical nature of the alignment detection system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.ar, E-mail: cabrera@fisica.unlp.edu.ar; Cabrera, A. F., E-mail: mizrahi@fisica.unlp.edu.ar, E-mail: cabrera@fisica.unlp.edu.ar; Desimoni, J.

We report a magnetic study on nanostructured (Fe{sub 79}Mn{sub 21}){sub 1−x}Cu{sub x} (0.00 ≤ x ≤ 0.30) alloys using static magnetic measurements. The alloys are mainly composed by an antiferromagnetic fcc phase and a disordered region that displays a spin-glass-like behavior. The interplay between the antiferromagnetic and magnetically disordered phases establishes an exchange anisotropy that gives rise to a loop shift at temperatures below the freezing temperature of moments belonging to the disordered region. The loop shift is more noticeable as the Cu content increases, which also enhances the spin-glass-like features. Further, in the x = 0.30 alloy the alignment imposed by applied magnetic fields highermore » than 4 kOe prevail over the configuration determined by the frustration mechanism that characterizes the spin glass-like phase.« less

Investigation of the two-quasiparticle bands in the doubly-odd nucleus 166Ta using a particle-number conserving cranked shell model

NASA Astrophysics Data System (ADS)

Zhang, ZhenHua

2016-07-01

The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hω are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

Gravitational wave searches for aligned-spin binary neutron stars using nonspinning templates

NASA Astrophysics Data System (ADS)

Cho, Hee-Suk; Lee, Chang-Hwan

2018-01-01

We study gravitational wave searches for merging binary neutron stars (NSs). We use nonspinning template waveforms towards the signals emitted from aligned-spin NS-NS binaries, in which the spins of the NSs are aligned with the orbital angular momentum. We use the TaylorF2 waveform model, which can generate inspiral waveforms emitted from aligned-spin compact binaries. We employ the single effective spin parameter χeff to represent the effect of two component spins (χ1, χ2) on the wave function. For a target system, we choose a binary consisting of the same component masses of 1.4 M ⊙ and consider the spins up to χ i = 0.4. We investigate fitting factors of the nonspinning templates to evaluate their efficiency in gravitational wave searches for the aligned-spin NS-NS binaries. We find that the templates can achieve the fitting factors exceeding 0.97 only for the signals in the range of -0.2 ≲ χeff ≲ 0. Therefore, we demonstrate the necessity of using aligned-spin templates not to lose the signals outside that range. We also show how much the recovered total mass can be biased from the true value depending on the spin of the signal.

KOI2138 -- a Spin-Orbit Aligned Intermediate Period Super-Earth

NASA Astrophysics Data System (ADS)

Barnes, Jason W.

2015-11-01

A planet's formation and evolution are encoded in spin-orbit alignment -- the planet's inclination relative to its star's equatorial plane. While the solar system's spin-orbit aligned planets indicate our own relatively quiescent history, many close-in giant planets show significant misalignment. Some planets even orbit retrograde! Hot Jupiters, then, have experienced fundamentally different histories than we experienced here in the solar system. In this presentation, I will show a new determination of the spin-orbit alignment of 2.1 REarth exoplanet candidate KOI2138. KOI2138 shows a gravity-darkened transit lightcurve that is consistent with spin-orbit alignment. This measurement is important because the only other super-Earth with an alignment determination (55 Cnc e, orbit period 0.74 days) is misaligned. With an orbital period of 23.55 days, KOI2138 is far enough from its star to avoid tidal orbit evolution. Therefore its orbit is likely primordial, and hence it may represent the tip of an iceberg of terrestrial, spin-orbit aligned planets that have histories that more closely resemble that of the solar system's terrestrial planets.

Searching for gravitational waves from compact binaries with precessing spins

NASA Astrophysics Data System (ADS)

Harry, Ian; Privitera, Stephen; Bohé, Alejandro; Buonanno, Alessandra

2016-07-01

Current searches for gravitational waves from compact-object binaries with the LIGO and Virgo observatories employ waveform models with spins aligned (or antialigned) with the orbital angular momentum. Here, we derive a new statistic to search for compact objects carrying generic (precessing) spins. Applying this statistic, we construct banks of both aligned- and generic-spin templates for binary black holes and neutron star-black hole binaries, and compare the effectualness of these banks towards simulated populations of generic-spin systems. We then use these banks in a pipeline analysis of Gaussian noise to measure the increase in background incurred by using generic- instead of aligned-spin banks. Although the generic-spin banks have roughly a factor of ten more templates than the aligned-spin banks, we find an overall improvement in signal recovery at a fixed false-alarm rate for systems with high-mass ratio and highly precessing spins. This gain in sensitivity comes at a small loss of sensitivity (≲4 %) for systems that are already well covered by aligned-spin templates. Since the observation of even a single binary merger with misaligned spins could provide unique astrophysical insights into the formation of these sources, we recommend that the method described here be developed further to mount a viable search for generic-spin binary mergers in LIGO/Virgo data.

Spin-orbit coupling induced two-electron relaxation in silicon donor pairs

NASA Astrophysics Data System (ADS)

Song, Yang; Das Sarma, S.

2017-09-01

We unravel theoretically a key intrinsic relaxation mechanism among the low-lying singlet and triplet donor-pair states in silicon, an important element in the fast-developing field of spintronics and quantum computation. Despite the perceived weak spin-orbit coupling (SOC) in Si, we find that our discovered relaxation mechanism, combined with the electron-phonon and interdonor interactions, drives the transitions in the two-electron states over a large range of donor coupling regimes. The scaling of the relaxation rate with interdonor exchange interaction J goes from J5 to J4 at the low to high temperature limits. Our analytical study draws on the symmetry analysis over combined band, donor envelope, and valley configurations. It uncovers naturally the dependence on the donor-alignment direction and triplet spin orientation, and especially on the dominant SOC source from donor impurities. While a magnetic field is not necessary for this relaxation, unlike in the single-donor spin relaxation, we discuss the crossover behavior with increasing Zeeman energy in order to facilitate comparison with experiments.

Measurements of spin alignment of vector mesons and global polarization of hyperons with ALICE at the LHC

NASA Astrophysics Data System (ADS)

Mohanty, Bedangadas

2018-02-01

We present the measurements related to global polarization of Λ hyperons and spin alignment of K*0 vector mesons at mid-rapidity for Pb-Pb collisions at = 2.76 TeV using the ALICE detector at the LHC. The global polarization measurements are carried out with respect to the first order event plane while the spin alignment measurements are carried out with respect to the production plane. No global polarization signal for Λ is observed for 5-15% and 15-50% central Pb-Pb collisions. The spin density matrix element ρ00 is found to have values slightly below ⅓ at low transverse momentum (pT) for K*0 mesons, while it is consistent with ⅓ (no spin alignment) at higher pT. No spin alignment is observed for K*0 in pp collisions at √s = 13 TeV and for the spin zero hadron K0S in 20-40% Pb-Pb collisions at = 2.76 TeV.

Coupled Electronic and Magnetic Phase Transition in the Infinite-Layer Phase LaSrNiRuO4.

PubMed

Patino, Midori Amano; Zeng, Dihao; Bower, Ryan; McGrady, John E; Hayward, Michael A

2016-09-06

Topochemical reduction of the ordered double perovskite LaSrNiRuO6 with CaH2 yields LaSrNiRuO4, an extended oxide phase containing infinite sheets of apex-linked, square-planar Ni(1+)O4 and Ru(2+)O4 units ordered in a checkerboard arrangement. At room temperature the localized Ni(1+) (d(9), S = (1)/2) and Ru(2+) (d(6), S = 1) centers behave paramagnetically. However, on cooling below 250 K the system undergoes a cooperative phase transition in which the nickel spins align ferromagnetically, while the ruthenium cations appear to undergo a change in spin configuration to a diamagnetic spin state. Features of the low-temperature crystal structure suggest a symmetry lowering Jahn-Teller distortion could be responsible for the observed diamagnetism of the ruthenium centers.

Spin configurations on a decorated square lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mert, Gülistan; Mert, H. Şevki

Spin configurations on a decorated square lattice are investigated using Bertaut’s microscopic method. We have obtained collinear and non-collinear (canted) modes for the given wave vectors in the ground state. We have found ferromagnetic and antiferromagnetic commensurate spin configurations. We have found canted incommensurate spin configurations.

Parameter Estimation for Compact Binaries with Ground-Based Gravitational-Wave Observations Using the LALInference

NASA Technical Reports Server (NTRS)

Veitch, J.; Raymond, V.; Farr, B.; Farr, W.; Graff, P.; Vitale, S.; Aylott, B.; Blackburn, K.; Christensen, N.; Coughlin, M.

2015-01-01

The Advanced LIGO and Advanced Virgo gravitational wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for the first detections. The gravitational waveforms emitted directly encode information about the sources, including the masses and spins of the compact objects. Recovering the physical parameters of the sources from the GW observations is a key analysis task. This work describes the LALInference software library for Bayesian parameter estimation of compact binary signals, which builds on several previous methods to provide a well-tested toolkit which has already been used for several studies. We show that our implementation is able to correctly recover the parameters of compact binary signals from simulated data from the advanced GW detectors. We demonstrate this with a detailed comparison on three compact binary systems: a binary neutron star (BNS), a neutron star - black hole binary (NSBH) and a binary black hole (BBH), where we show a cross-comparison of results obtained using three independent sampling algorithms. These systems were analysed with non-spinning, aligned spin and generic spin configurations respectively, showing that consistent results can be obtained even with the full 15-dimensional parameter space of the generic spin configurations. We also demonstrate statistically that the Bayesian credible intervals we recover correspond to frequentist confidence intervals under correct prior assumptions by analysing a set of 100 signals drawn from the prior. We discuss the computational cost of these algorithms, and describe the general and problem-specific sampling techniques we have used to improve the efficiency of sampling the compact binary coalescence (CBC) parameter space.

Extending the Cutoff Wavelength of Thermophotovoltaic Devices via Band Structure Engineering

NASA Astrophysics Data System (ADS)

Lee, Michael Steven

Complex oxides, solid-state compounds comprised of oxygen and at least two metal cations, are an intriguing class of materials for implementation into future microelectronic devices. They possess a wide range of functional properties, such as magnetism, ferroelectricity, and superconductivity, that can all be readily modified by their sensitivity to lattice strain, electronic and magnetic fields, chemical doping, and other external stimuli. This sensitivity makes complex oxides highly capable materials, but also introduces many technical challenges. The work of this dissertation has focused on extending our current knowledge of the magnetic materials properties and interfacial effects present in epitaxial films into micro- and nanoscale features. Ferromagnetic (FM) spin textures are arrangements of magnetic moments within such patterned features. Their switching behaviors are essential components of current data storage applications, and complex oxides are ideal candidates for future designs. In any materials system, the deviation from bulk or thin film properties when scaling down to nanostructures can be difficult to predict due to either size induced effects or consequences of the fabrication process itself. Therefore, these magnetic films and multilayers must be studied in the modified state to understand the challenges and opportunities associated with designing practical structures. Soft x-ray photoemission electron microscopy (X-PEEM) was used to observe and characterize the evolution of magnetic domain structure as a function of temperature in micromagnets patterned into epitaxial films of La0.7 Sr0.3MnO3 (LSMO). These images reveal the formation of novel spin textures that are a hybridization of well-described configurations, vortex and Landau, and emerge from the balance between fundamental materials parameters, micromagnet geometries, and epitaxial strain. Furthermore, slight perturbations to the lattice near the lithographically defined microstructure edges are shown to induce long range suppression of the magnetocrystalline anisotropy while other magnetic parameters, such as the saturation magnetization, remain unchanged. The results demonstrate how the magnetic domain state can be tailored through careful incorporation of these factors. Additional complexity is added to the system by interfacing LSMO with antiferromagnetic (AFM) LaFeO3 (LFO) or La0.7Sr 0.3FeO3 (LSFO). In unpatterned bilayers and superlattices, exchange coupling across the FM/AFM interface promotes a perpendicular alignment of the FM and AFM spin axes. Within patterned bilayers the alignment can be driven into a parallel configuration through changes in the micromagnet width, crystallographic orientation, and temperature. The importance of FM/AFM spin alignment is emphasized by magnetic reversal experiments of individual magnetic bits that demonstrate the coercivity can be adjusted over a wide range relative to LSMO single-layer micromagnets. In a superlattice of FM/AFM interfaces, the relative influence of the LSMO is reduced as the TC drops from 360 K to 80 K due to the ultra-thin sublayer thickness. Like the initial study on LSMO, the magnetocrystalline anisotropy of the LSFO layer is fully suppressed near microstructure edges, and the AFM domain configuration is entirely dictated by a magnetostatic-type effect in that region. This behavior persists both above and below the TC (with spin-flop coupling preserved) suggesting a new method to control AFM spin textures which are typically pinned to stochastic structural domains and defects and require large fields to manipulate.

Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

PubMed

Farr, Will M; Stevenson, Simon; Miller, M Coleman; Mandel, Ilya; Farr, Ben; Vecchio, Alberto

2017-08-23

The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10 -7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

Davisson-Germer Prize in Atomic or Surface Physics Talk: Soft X-Ray Studies of Surfaces, Interfaces and Thin Films: From Spectroscopy to Ultrafast Nanoscale Movies

NASA Astrophysics Data System (ADS)

Stöhr, Joachim

2011-03-01

My talk will review the development of soft x-ray spectroscopy and microscopy and its impact on our understanding of chemical bonding, magnetism and dynamics at surfaces and interfaces. I will first outline important soft x-ray spectroscopy and microscopy techniques that have been developed over the last 30 years and their key strengths such as elemental and chemical specificity, sensitivity to small atomic concentrations, separation of charge and spin properties, spatial resolution down to the nanometer scale, and temporal resolution down to the intrinsic femtosecond timescale of atomic and electronic motions. I will then present scientific breakthroughs based on soft x-ray studies in three selected areas: the nature of molecular bonding and reactivity on metal surfaces, the molecular origin of liquid crystal alignment on surfaces, and the microscopic origin of interface-mediated spin alignments in modern magnetic devices. My talk will also cover the use of soft x-rays for revealing the temporal evolution of electronic structure, addressing the key problem of ``function,'' down to the intrinsic femtosecond time scale of charge and spin configuration changes. As examples I will present the formation and breaking of chemical bonds in surface complexes and the motion of the magnetization in magnetic devices. Work supported by the Office of Basic Energy Science of the US Department of Energy.

Bi-quadratic interlayer exchange coupling in Co{sub 2}MnSi/Ag/Co{sub 2}MnSi pseudo spin-valve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goripati, Hari S.; Hono, K.; Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-0047

2011-12-15

Bi-quadratic interlayer exchange coupling is found below 100 K in a Co{sub 2}MnSi/Ag/Co{sub 2}MnSi current-perpendicular-to-plane pseudo spin valves. The bi-quadratic coupling constant J{sub 2} was estimated to be {approx}-0.30 erg/cm{sup 2} at 5 K and the strong temperature dependence of the coupling strength points its likely origin to the ''loose spin'' model. Application of current of {approx}2 x 10{sup 7} A/cm{sup 2} below 100 K leads to an increase in the magnetoresistance (MR), indicating current induced antiparallel alignment of the two magnetic layers. These results strongly suggest that the presence of the bi-quadratic interlayer exchange coupling causes the reduction ofmore » the magnetoresistance at low temperature and illustrates the importance of understanding the influence of interlayer exchange coupling on magnetization configuration in magnetic nanostructures.« less

Controlling entangled spin-orbit coupling of 5 d states with interfacial heterostructure engineering

DOE PAGES

Kim, J. -W.; Choi, Y.; Chun, S. H.; ...

2018-03-26

Here, the combination of strong electron correlations in 3d transition metal oxides and spin-orbit interactions in the 5d counterpart can give rise to exotic electronic and magnetic properties. Here, the nature of emerging phenomena at the interface between SrIrO 3 (SIO) and La 2/3Sr 1/3MnO 3 (LSMO) is presented. Nominally, SIO with strong spin-orbit interaction is metallic and nonmagnetic on the verge of a metal-insulator transition, whereas LSMO is metallic and ferromagnetic with itinerant character and high spin polarization. In the 1:1 LSMO/SIO superlattice, we observe ferromagnetic Mn moments with an insulating behavior, accompanied by antiferromagnetic ordering in SIO. Element-resolvedmore » x-ray magnetic circular dichroism proves that there is a weak net ferromagnetic Ir moment aligned antiparallel to the Mn counterpart. The branching ratio shows the formation of molecular-orbitals between the Mn and Ir layers modifying the Ir 5d electronic configuration through the mixture of t 2g and e g states, resulting in a deviation from J eff = ½. This result demonstrates a pathway to manipulate the spin-orbit entanglement in 5d states with 2-dimensional 3d spin-polarized electrons through heterostructure design.« less

Controlling entangled spin-orbit coupling of 5 d states with interfacial heterostructure engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J. -W.; Choi, Y.; Chun, S. H.

Here, the combination of strong electron correlations in 3d transition metal oxides and spin-orbit interactions in the 5d counterpart can give rise to exotic electronic and magnetic properties. Here, the nature of emerging phenomena at the interface between SrIrO 3 (SIO) and La 2/3Sr 1/3MnO 3 (LSMO) is presented. Nominally, SIO with strong spin-orbit interaction is metallic and nonmagnetic on the verge of a metal-insulator transition, whereas LSMO is metallic and ferromagnetic with itinerant character and high spin polarization. In the 1:1 LSMO/SIO superlattice, we observe ferromagnetic Mn moments with an insulating behavior, accompanied by antiferromagnetic ordering in SIO. Element-resolvedmore » x-ray magnetic circular dichroism proves that there is a weak net ferromagnetic Ir moment aligned antiparallel to the Mn counterpart. The branching ratio shows the formation of molecular-orbitals between the Mn and Ir layers modifying the Ir 5d electronic configuration through the mixture of t 2g and e g states, resulting in a deviation from J eff = ½. This result demonstrates a pathway to manipulate the spin-orbit entanglement in 5d states with 2-dimensional 3d spin-polarized electrons through heterostructure design.« less

Controlling entangled spin-orbit coupling of 5 d states with interfacial heterostructure engineering

NASA Astrophysics Data System (ADS)

Kim, J.-W.; Choi, Y.; Chun, S. H.; Haskel, D.; Yi, D.; Ramesh, R.; Liu, J.; Ryan, P. J.

2018-03-01

The combination of strong electron correlations in 3 d transition-metal oxides and spin-orbit interactions in the 5 d counterpart can give rise to exotic electronic and magnetic properties. Here, the nature of emerging phenomena at the interface between SrIr O3 (SIO) and L a2 /3S r1 /3Mn O3 (LSMO) is presented. Nominally, SIO with strong spin-orbit interaction is metallic and nonmagnetic on the verge of a metal-insulator transition, whereas LSMO is metallic and ferromagnetic with itinerant character and high spin polarization. In the 1:1 LSMO/SIO superlattice, we observe ferromagnetic Mn moments with an insulating behavior, accompanied by antiferromagnetic ordering in SIO. Element-resolved x-ray magnetic circular dichroism proves that there is a weak net ferromagnetic Ir moment aligned antiparallel to the Mn counterpart. The branching ratio shows the formation of molecular orbitals between the Mn and Ir layers modifying the Ir 5 d electronic configuration through the mixture of t2 g and eg states, resulting in a deviation from Jeff=1 /2 . This result demonstrates a pathway to manipulate the spin-orbit entanglement in 5 d states with two-dimensional 3 d spin-polarized electrons through heterostructure design.

Ecology of dark matter haloes - II. Effects of interactions on the alignment of halo pairs

NASA Astrophysics Data System (ADS)

L'Huillier, Benjamin; Park, Changbom; Kim, Juhan

2017-04-01

We use the Horizon Run 4 cosmological N-body simulation to study the effects of distant and close interactions on the alignments of the shapes, spins and orbits of targets haloes with their neighbours, and their dependence on the local density environment and neighbour separation. Interacting targets have a significantly lower spin and higher sphericity and oblateness than all targets. Interacting pairs initially have antiparallel spins, but the spins develop parallel alignment as time goes on. Neighbours tend to evolve in the plane of rotation of the target, and in the direction of the major axis of prolate haloes. Moreover, interactions are preferentially radial, while pairs with non-radial orbits are preferentially prograde. The alignment signals are stronger at high mass and for close separations, and independent of the large-scale density. Positive alignment signals are found at redshifts up to 4, and increase with decreasing redshifts. Moreover, the orbits tend to become prograde at low redshift, while no alignment is found at high redshift (z = 4).

Gravitational-Wave Data Analysis with Spinning Merger-Ringdown Waveforms

NASA Technical Reports Server (NTRS)

Kelly Bernard J.

2011-01-01

The recent availability of high-quality, gravitational merger-ringdown waveforms from spinning black-hole systems has made possible the development of multi-mode GW templates for use in data-analysis studies of current and proposed interferometric GW detectors. We report on recent work at NASA Goddard, analyzing the most significant modes from aligned-spin black-hole-binary mergers. From these, we have developed time-domain merger-ringdown GW templates covering the aligned-spin portion of parameter space. We also discuss how using the full information content of aligned-spin mergers can significantly reduce uncertainties in some parameters, emphasizing the significant gains possible in the last stages of merger, inaccessible to inspiral-only post-Newtonian templates.

Temperature dependence of ferromagnet-antiferromagnet spin alignment and coercivity in epitaxial micromagnet bilayers

DOE PAGES

Lee, Michael S.; Wynn, Thomas A.; Folven, Erik; ...

2017-06-26

In this paper, soft x-ray photoemission electron microscopy with an in situ magnetic field has been used to study the relationship between ferromagnetic and antiferromagnetic spin alignment and the switching/reversal field of epitaxial micromagnetic structures. We investigated a model system consisting of a bilayer of ferromagnetic La 0.7Sr 0.3MnO 3 and antiferromagnetic LaFeO 3 where the spin axes in each layer can be driven from mutually perpendicular (spin-flop) to parallel alignment by varying the temperature between 30 and 300 K. Results show that not only does this spin alignment noticeably influence the bilayer micromagnet coercivity compared to La 0.7Sr 0.3MnOmore » 3 single-layer micromagnets, but the coercivity within this materials system can be tuned over a wide range by careful balance of material properties.« less

Temperature dependence of ferromagnet-antiferromagnet spin alignment and coercivity in epitaxial micromagnet bilayers

NASA Astrophysics Data System (ADS)

Lee, Michael S.; Wynn, Thomas A.; Folven, Erik; Chopdekar, Rajesh V.; Scholl, Andreas; Retterer, Scott T.; Grepstad, Jostein K.; Takamura, Yayoi

2017-06-01

Soft x-ray photoemission electron microscopy with an in situ magnetic field has been used to study the relationship between ferromagnetic and antiferromagnetic spin alignment and the switching/reversal field of epitaxial micromagnetic structures. We investigated a model system consisting of a bilayer of ferromagnetic L a0.7S r0.3Mn O3 and antiferromagnetic LaFe O3 where the spin axes in each layer can be driven from mutually perpendicular (spin-flop) to parallel alignment by varying the temperature between 30 and 300 K. Results show that not only does this spin alignment noticeably influence the bilayer micromagnet coercivity compared to L a0.7S r0.3Mn O3 single-layer micromagnets, but the coercivity within this materials system can be tuned over a wide range by careful balance of material properties.

High spin states in 162Lu

NASA Astrophysics Data System (ADS)

Gupta, S. L.; Pancholi, S. C.; Juneja, P.; Mehta, D.; Kumar, Ashok; Bhowmik, R. K.; Muralithar, S.; Rodrigues, G.; Singh, R. P.

1997-09-01

An experimental investigation of the odd-odd 162Lu nucleus, following the 148Sm(19F,5n) reaction at beam energy Elab=112 MeV, has been performed through in-beam gamma-ray spectroscopy. It revealed three signature-split bands. The yrast band based on πh11/2⊗νi13/2 configuration exhibits anomalous signature splitting (the unfavored signature Routhian lying lower than the favored one) whose magnitude Δe'~25 keV, is considerably reduced in contrast to sizable normal signature splitting Δe'~125 and 60 keV observed in the yrast πh11/2 bands of the neighboring odd-A 161,163Lu nuclei, respectively. The signature inversion in this band occurs at spin ~20ħ (frequency=0.37 MeV). The second signature-split band, observed above the band crossing associated with the alignment of a pair of i13/2 quasineutrons, is a band based on the four-quasiparticle [πh11/2[523]7/2-⊗νh9/2[521]3/2-⊗(νi13/2)2], i.e., EABAp(Bp), configuration. The third signature-split band is also likely to be a four-quasiparticle band with configuration similar to the second band but involving F quasineutron, i.e., FABAp(Bp). The experimental results are discussed in comparison with the existing data in the neighboring nuclei and in the framework of the cranking shell model.

ϕ Meson Spin Alignment and the Azimuthal Angle Dependence of Λ (Λ) Polarization in Au+Au collisions at RHIC

NASA Astrophysics Data System (ADS)

Tu, Biao

2018-02-01

Initial large global angular momentum in non-central relativistic heavy-ion collisions can produce strong vorticity, and through the spin-orbit coupling, causes the spin of particles to align with the system's global angular momentum. We present the azimuthal angle dependent (relative to the reaction plane) polarization for Λ and Λ in mid-central Au+Au collisions at = 200 GeV. We also present the ϕ meson spin alignment parameter, ρ00 in Au+Au collisions at = 19.6, 27, 39, 62.4 and 200 GeV. The implications of the results are discussed.

SPIN ALIGNMENTS OF SPIRAL GALAXIES WITHIN THE LARGE-SCALE STRUCTURE FROM SDSS DR7

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Youcai; Yang, Xiaohu; Luo, Wentao

Using a sample of spiral galaxies selected from the Sloan Digital Sky Survey Data Release 7 and Galaxy Zoo 2, we investigate the alignment of spin axes of spiral galaxies with their surrounding large-scale structure, which is characterized by the large-scale tidal field reconstructed from the data using galaxy groups above a certain mass threshold. We find that the spin axes only have weak tendencies to be aligned with (or perpendicular to) the intermediate (or minor) axis of the local tidal tensor. The signal is the strongest in a cluster environment where all three eigenvalues of the local tidal tensor aremore » positive. Compared to the alignments between halo spins and the local tidal field obtained in N-body simulations, the above observational results are in best agreement with those for the spins of inner regions of halos, suggesting that the disk material traces the angular momentum of dark matter halos in the inner regions.« less

Flight investigation of the effect of tail configuration on stall, spin, and recovery characteristics of a low-wing general aviation research airplane

NASA Technical Reports Server (NTRS)

Stough, H. Paul, III; Patton, James M., Jr.; Sliwa, Steven M.

1987-01-01

Flight tests were performed to investigate the stall, spin, and recovery characteristics of a low-wing, single-engine, light airplane with four interchangeable tail configurations. The four tail configurations were evaluated for effects of varying mass distribution, center-of-gravity position, and control inputs. The airplane tended to roll-off at the stall. Variations in tail configuration produced spins ranging from 40 deg to 60 deg angle of attack and turn rates of about 145 to 208 deg/sec. Some unrecoverable flat spins were encountered which required use of the airplane spin chute for recovery. For recoverable spins, antispin rudder followed by forward wheel with ailerons centered provided the quickest spin recovery. The moderate spin modes agreed very well with those predicted from spin-tunnel model tests, however, the flat spin was at a lower angle of attack and a slower rotation rate than indicated by the model tests.

Monopole-driven shell evolution below the doubly magic nucleus 132Sn explored with the long-lived isomer in 126Pd.

PubMed

Watanabe, H; Lorusso, G; Nishimura, S; Otsuka, T; Ogawa, K; Xu, Z Y; Sumikama, T; Söderström, P-A; Doornenbal, P; Li, Z; Browne, F; Gey, G; Jung, H S; Taprogge, J; Vajta, Zs; Wu, J; Yagi, A; Baba, H; Benzoni, G; Chae, K Y; Crespi, F C L; Fukuda, N; Gernhäuser, R; Inabe, N; Isobe, T; Jungclaus, A; Kameda, D; Kim, G D; Kim, Y K; Kojouharov, I; Kondev, F G; Kubo, T; Kurz, N; Kwon, Y K; Lane, G J; Moon, C-B; Montaner-Pizá, A; Moschner, K; Naqvi, F; Niikura, M; Nishibata, H; Nishimura, D; Odahara, A; Orlandi, R; Patel, Z; Podolyák, Zs; Sakurai, H; Schaffner, H; Simpson, G S; Steiger, K; Suzuki, H; Takeda, H; Wendt, A; Yoshinaga, K

2014-07-25

A new isomer with a half-life of 23.0(8) ms has been identified at 2406 keV in (126)Pd and is proposed to have a spin and parity of 10(+) with a maximally aligned configuration comprising two neutron holes in the 1h(11/2) orbit. In addition to an internal-decay branch through a hindered electric octupole transition, β decay from the long-lived isomer was observed to populate excited states at high spins in (126)Ag. The smaller energy difference between the 10(+) and 7(-) isomers in (126)Pd than in the heavier N=80 isotones can be interpreted as being ascribed to the monopole shift of the 1h(11/2) neutron orbit. The effects of the monopole interaction on the evolution of single-neutron energies below (132)Sn are discussed in terms of the central and tensor forces.

Stabilization of He2(A(sup 3)Sigma(sub u)(+)) molecules in liquid helium by optical pumping for vacuum UV laser

NASA Technical Reports Server (NTRS)

Zmuidzinas, J. S. (Inventor)

1978-01-01

A technique is disclosed for achieving large populations of metastable spin-aligned He2(a 3 Sigma u +) molecules in superfluid helium to obtain lasing in the vacuum ultraviolet wavelength regime around 0.0800 micron m by electronically exciting liquid (superfluid) helium with a comparatively low-current electron beam and spin aligning the metastable molecules by means of optical pumping with a modestly-powered (100mW) circularly-polarized continuous wave laser operating at, for example, 0.9096 or 0.4650 micron m. Once a high concentration of spin-aligned He2 (a 3 Sigma u +) is achieved with lifetimes of a few milliseconds, a strong microwave signal destroys the spin alignment and induces a quick collisional transition of He2 (a 3 Sigma u +) molecules to the a 1 Sigma u + state and thereby a lasing transition to the X 1 Sigma g + state.

Measuring Parameters of Massive Black Hole Binaries with Partially-Aligned Spins

NASA Technical Reports Server (NTRS)

Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

2010-01-01

It is important to understand how well the gravitational-wave observatory LISA can measure parameters of massive black hole binaries. It has been shown that including spin precession in the waveform breaks degeneracies and produces smaller expected parameter errors than a simpler, precession-free analysis. However, recent work has shown that gas in binaries can partially align the spins with the orbital angular momentum, thus reducing the precession effect. We show how this degrades the earlier results, producing more pessimistic errors in gaseous mergers. However, we then add higher harmonics to the signal model; these also break degeneracies, but they are not affected by the presence of gas. The harmonics often restore the errors in partially-aligned binaries to the same as, or better than/ those that are obtained for fully precessing binaries with no harmonics. Finally, we investigate what LISA measurements of spin alignment can tell us about the nature of gas around a binary,

Measuring Parameters of Massive Black Hole Binaries with Partially Aligned Spins

NASA Technical Reports Server (NTRS)

Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

2011-01-01

The future space-based gravitational wave detector LISA will be able to measure parameters of coalescing massive black hole binaries, often to extremely high accuracy. Previous work has demonstrated that the black hole spins can have a strong impact on the accuracy of parameter measurement. Relativistic spin-induced precession modulates the waveform in a manner which can break degeneracies between parameters, in principle significantly improving how well they are measured. Recent studies have indicated, however, that spin precession may be weak for an important subset of astrophysical binary black holes: those in which the spins are aligned due to interactions with gas. In this paper, we examine how well a binary's parameters can be measured when its spins are partially aligned and compare results using waveforms that include higher post-Newtonian harmonics to those that are truncated at leading quadrupole order. We find that the weakened precession can substantially degrade parameter estimation, particularly for the "extrinsic" parameters sky position and distance. Absent higher harmonics, LISA typically localizes the sky position of a nearly aligned binary about an order of magnitude less accurately than one for which the spin orientations are random. Our knowledge of a source's sky position will thus be worst for the gas-rich systems which are most likely to produce electromagnetic counterparts. Fortunately, higher harmonics of the waveform can make up for this degradation. By including harmonics beyond the quadrupole in our waveform model, we find that the accuracy with which most of the binary's parameters are measured can be substantially improved. In some cases, the improvement is such that they are measured almost as well as when the binary spins are randomly aligned.

In-Beam Studies of High-Spin States in Mercury -184 and MERCURY-193 and Polarization Studies

NASA Astrophysics Data System (ADS)

Deng, Jingkang

The high-spin states in ^{184 }Hg and ^{193}Hg were studied by using the reactions ^{156 }Gd(^{32}S, 4n)^{184}Hg, in the spin spectrometer and ^{150}Nd( ^{48}Ca, 5n)^ {193}Hg, in the gamma -ray spectrometer, respectively, with the beams provided by the 25 MV tandem accelerator at the Holifield Heavy Ion Research Facility. Seven new rotational bands were observed for the first time in ^{184}Hg based on gamma-gamma coincidences with the use of a multiplicity filter. Spin assignments were based on the measured directional correlations for oriented nuclei (DCO ratios). The well-deformed prolate band was tentatively extended to 26^+ state. One new band in ^{184} Hg has a moment of inertia very similar to that of the s-band in ^{186}Hg which is assigned a (651, 1/2) otimes (770, 1/2) neutron configuration. However, it starts with a spin state of 5hbar, while the s-band in the ^{186}Hg starts with a I^pi = 11 ^- state. Some other bands were found in ^{184}Hg which are similar to ones in ^{186}Hg. However a pair of signature partner bands without signature splitting not seen in ^{186}Hg is observed. It shows the same alignment pattern below the band crossing with the bands in ^{182 }Pt and ^{180}Os lying in the N = 104 chain which consist of a nu(i_{13/2}h_{9/2} ) or nu(i_{13/2}f _{7/2}) configuration. A decay sequence above the 47/2, 5.4 MeV level in ^{193}Hg was established through discrete gamma-ray spectroscopy. This sequence was shown to feed several previously known levels in ^{193}Hg. The new energy levels exhibit non-collective single-particle character implying the dominant role of particle alignment mode at the moderate spin. This is in contrast to the collective bands observed in nearby lead isotope. The polarization detection efficiency of a symmetrical four Ge detector Compton polarimeter with the four detectors housed in one cryostat was measured by using the UNISOR low temperature nuclear orientation facility at HHIRF. It was shown that this Compton polarimeter has superior polarization detection efficiency compared to three detector and multisegment detector designs. It is suitable for polarization measurements in both low temperature and in-beam nuclear orientation studies. This detector was used during an in-beam spectroscopic study of ^{186}Hg and provided the crucial data which yielded a change in parity for the new band with deformation intermediate between normal and superdeformation in ^{186 }Hg.

A spin-orbit alignment for the hot Jupiter HATS-3b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Addison, B. C.; Tinney, C. G.; Wright, D. J.

We have measured the alignment between the orbit of HATS-3b (a recently discovered, slightly inflated Hot Jupiter) and the spin axis of its host star. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The sky-projected spin-orbit angle of λ = 3° ± 25° was determined from spectroscopic measurements of the Rossiter-McLaughlin effect. This is the first exoplanet discovered through the HATSouth transit survey to have its spin-orbit angle measured. Our results indicate that the orbital plane of HATS-3b is consistent with being aligned to the spin axismore » of its host star. The low obliquity of the HATS-3 system, which has a relatively hot mid F-type host star, agrees with the general trend observed for Hot Jupiter host stars with effective temperatures >6250 K to have randomly distributed spin-orbit angles.« less

A variational Monte Carlo study of different spin configurations of electron-hole bilayer

NASA Astrophysics Data System (ADS)

Sharma, Rajesh O.; Saini, L. K.; Bahuguna, Bhagwati Prasad

2018-05-01

We report quantum Monte Carlo results for mass-asymmetric electron-hole bilayer (EHBL) system with different-different spin configurations. Particularly, we apply a variational Monte Carlo method to estimate the ground-state energy, condensate fraction and pair-correlations function at fixed density rs = 5 and interlayer distance d = 1 a.u. We find that spin-configuration of EHBL system, which consists of only up-electrons in one layer and down-holes in other i.e. ferromagnetic arrangement within layers and anti-ferromagnetic across the layers, is more stable than the other spin-configurations considered in this study.

Environment overwhelms both nature and nurture in a model spin glass

NASA Astrophysics Data System (ADS)

Middleton, A. Alan; Yang, Jie

We are interested in exploring what information determines the particular history of the glassy long term dynamics in a disordered material. We study the effect of initial configurations and the realization of stochastic dynamics on the long time evolution of configurations in a two-dimensional Ising spin glass model. The evolution of nearest neighbor correlations is computed using patchwork dynamics, a coarse-grained numerical heuristic for temporal evolution. The dependence of the nearest neighbor spin correlations at long time on both initial spin configurations and noise histories are studied through cross-correlations of long-time configurations and the spin correlations are found to be independent of both. We investigate how effectively rigid bond clusters coarsen. Scaling laws are used to study the convergence of configurations and the distribution of sizes of nearly rigid clusters. The implications of the computational results on simulations and phenomenological models of spin glasses are discussed. We acknowledge NSF support under DMR-1410937 (CMMT program).

THE FINAL SPIN FROM BINARY BLACK HOLES IN QUASI-CIRCULAR ORBITS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofmann, Fabian; Rezzolla, Luciano; Barausse, Enrico

2016-07-10

We revisit the problem of predicting the spin magnitude and direction of the black hole (BH) resulting from the merger of two BHs with arbitrary masses and spins inspiraling in quasi-circular orbits. We do this by analyzing a catalog of 619 recent numerical-relativity simulations collected from the literature and spanning a large variety of initial conditions. By combining information from the post-Newtonian approximation, the extreme mass-ratio limit, and perturbative calculations, we improve our previously proposed phenomenological formulae for the final remnant spin. In contrast with alternative suggestions in the literature, and in analogy with our previous expressions, the new formulamore » is a simple algebraic function of the initial system parameters and is not restricted to binaries with spins aligned/anti-aligned with the orbital angular momentum but can be employed for fully generic binaries. The accuracy of the new expression is significantly improved, especially for almost extremal progenitor spins and for small mass ratios, yielding an rms error σ ≈ 0.002 for aligned/anti-aligned binaries and σ ≈ 0.006 for generic binaries. Our new formula is suitable for cosmological applications and can be employed robustly in the analysis of the gravitational waveforms from advanced interferometric detectors.« less

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

NASA Astrophysics Data System (ADS)

Hinz, C.; Gumbsheimer, P.; Traum, C.; Holtkemper, M.; Bauer, B.; Haase, J.; Mahapatra, S.; Frey, A.; Brunner, K.; Reiter, D. E.; Kuhn, T.; Seletskiy, D. V.; Leitenstorfer, A.

2018-01-01

We study the dynamics of photoexcited electrons and holes in single negatively charged CdSe/ZnSe quantum dots with two-color femtosecond pump-probe spectroscopy. An initial characterization of the energy level structure is performed at low temperatures and magnetic fields of up to 5 T. Emission and absorption resonances are assigned to specific transitions between few-fermion states by a theoretical model based on a configuration interaction approach. To analyze the dynamics of individual charge carriers, we initialize the quantum system into excited trion states with defined energy and spin. Subsequently, the time-dependent occupation of the trion ground state is monitored by spectrally resolved differential transmission measurements. We observe subpicosecond dynamics for a hole excited to the D shell. The energy dependence of this D -to-S shell intraband transition is investigated in quantum dots of varying size. Excitation of an electron-hole pair in the respective p shells leads to the formation of singlet and triplet spin configurations. Relaxation of the p -shell singlet is observed to occur on a time scale of a few picoseconds. Pumping of p -shell triplet transitions opens up two pathways with distinctly different scattering times. These processes are shown to be governed by the mixing of singlet and triplet states due to exchange interactions enabling simultaneous electron and hole spin flips. To isolate the relaxation channels, we align the spin of the residual electron by a magnetic field and employ laser pulses of defined helicity. This step provides ultrafast preparation of a fully inverted trion ground state of the quantum dot with near unity probability, enabling deterministic addition of a single photon to the probe pulse. Therefore our experiments represent a significant step towards using single quantum emitters with well-controled inversion to manipulate the photon statistics of ultrafast light pulses.

THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Setiawan, Johny

With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars ({beta}{sub p} = -1. Degree-Sign 8 {+-} 1. Degree-Sign 6 and |{beta}{sub s}| < 17 Degree-Sign ). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DImore » Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from synchronization (they are spinning nine times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes.« less

Training effect in specular spin valves

NASA Astrophysics Data System (ADS)

Ventura, J.; Araujo, J. P.; Sousa, J. B.; Veloso, A.; Freitas, P. P.

2008-05-01

Specular spin valves show an enhanced giant magnetoresistive (GMR) ratio due to specular reflection in nano-oxide layers (NOLs) formed by the partial oxidation of CoFe pinned and free layers. The oxides that form the (pinned layer) NOL were recently shown to antiferromagnetically order at Ttilde 175K . Here, we study the training effect (TE) in MnIr/CoFe/NOL/CoFe/Cu/CoFe/NOL/Ta specular spin valves in the 300-15 K temperature range. The exchange bias direction between the MnIr and CoFe layers impressed during annealing is taken as the positive direction. The training effect is observed in antiferromagnetic (AFM)/ferromagnetic (FM) exchange systems and related to the rearrangement of interfacial AFM spin structure with the number of hysteretic cycles performed (n) , resulting in the decrease of the exchange field (Hexch) . Here, in the studied specular spin valve, TE was only observed for T<175K and is thus related to the pinned layer NOL-AFM ordering and to the evolution of the corresponding spin structure with n . We show that FM spins that are strongly coupled to AFM domains do not align with the applied positive magnetic field (H) , giving rise to a residual MR at H≫0 . Such nonsaturating MR will be related with a spin-glass-like behavior of the interfacial magnetism induced by the nano-oxide layer. The observed dependence of the training effect on the field cooling procedure is also likely associated with the existence of different spin configurations available in the magnetically disordered oxide. Furthermore, anomalous magnetoresistance cycles measured after cooling runs under -500Oe are here related to induced NOL exchange bias/applied magnetic field misalignment. The temperature dependence of the training effect was obtained and fitted by using a recent theoretical model.

Building up the spin - orbit alignment of interacting galaxy pairs

NASA Astrophysics Data System (ADS)

Moon, Jun-Sung; Yoon, Suk-Jin

2018-01-01

Galaxies are not just randomly distributed throughout space. Instead, they are in alignment over a wide range of scales from the cosmic web down to a pair of galaxies. Motivated by recent findings that the spin and the orbital angular momentum vectors of galaxy pairs tend to be parallel, we here investigate the spin - orbit orientation in close pairs using the Illustris cosmological simulation. We find that since z ~ 1, the parallel alignment has become progressively stronger with time through repetitive encounters. The pair Interactions are preferentially in prograde at z = 0 (over 5 sigma significance). The prograde fraction at z = 0 is larger for the pairs influenced more heavily by each other during their evolution. We find no correlation between the spin - orbit orientation and the surrounding large-scale structure. Our results favor the scenario in which the alignment in close pairs is caused by tidal interactions later on, rather than the primordial torquing by the large-scale structures.

Resonant optical alignment and orientation of Mn2+ spins in CdMnTe crystals

NASA Astrophysics Data System (ADS)

Baryshnikov, K. A.; Langer, L.; Akimov, I. A.; Korenev, V. L.; Kusrayev, Yu. G.; Averkiev, N. S.; Yakovlev, D. R.; Bayer, M.

2015-11-01

We report on spin orientation and alignment of Mn2 + ions in (Cd,Mn)Te diluted magnetic semiconductor crystals using resonant intracenter excitation with circular- and linear-polarized light. The resulting polarized emission of the magnetic ions is observed at low temperatures when the spin relaxation time of the Mn2 + ions is in the order of 1 ms , which considerably exceeds the photoluminescence decay time of 23 μ s . We demonstrate that the experimental data on optical orientation and alignment of Mn2 + ions can be explained using a phenomenological model that is based on the approximation of isolated centers.

Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Li-Ling; School of Science, Hunan University of Technology, Zhuzhou 412007; Yang, Bing-Chu, E-mail: bingchuyang@csu.edu.cn

2014-07-21

Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also bemore » shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.« less

Nucleon Alignment and Shape Competition at High Spin in ^180Hf

NASA Astrophysics Data System (ADS)

Tandel, U. S.; Chowdhury, P.; Tandel, S. K.; Sheppard, S.; Cline, D.; Wu, C. Y.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Zhu, S.

2006-10-01

In light even-N Hf isotopes (N = 96-106), the first i13/2 neutron alignment occurs at hφ< 0.3 MeV. In contrast, no alignment was observed up to ˜ 0.4 MeV in ^180,182Hf (N = 108,110) [1]. Theoretical calculations predict that oblate collective rotation becomes yrast at high spins in ^180Hf [2, 3]. In the present work, the yrast band of ^180Hf has been extended to high spins, via inelastic excitation, using a 1300 MeV ^180Hf beam incident on a thin ^232Th target. The γ rays were detected by Gammasphere, with event by event Doppler correction and Q-value selectivity provided by CHICO. The data reveal onset of the first nucleon alignment in ^180Hf at hφ ˜ 0.43 MeV, which is significantly higher than predictions (˜ 0.35 MeV). Interestingly, the γ-vibrational band is crossed by a band with apparent high moment-of-inertia at ˜ 0.25 MeV. This structure, which becomes near yrast at the highest observed spins will be discussed in the context of nucleon alignment and shape competition at high spin in ^180Hf. [1] E. Ngijoi-Yogo, Ph.D. thesis, U.Mass. Lowell (2004) [2] R.R. Hilton and H.J. Mang, Phys. Rev. Lett. 43, 1979 (1979). [3] F.R. Xu et al., Phys. Rev. C62, 014301 (2000).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnes, Jason W., E-mail: jwbarnes@uidaho.ed

Main-sequence stars earlier than spectral-type approxF6 or so are expected to rotate rapidly due to their radiative exteriors. This rapid rotation leads to an oblate stellar figure. It also induces the photosphere to be hotter (by up to several thousand kelvin) at the pole than at the equator as a result of a process called gravity darkening that was first predicted by von Zeipel. Transits of extrasolar planets across such a non-uniform, oblate disk yield unusual and distinctive lightcurves that can be used to determine the relative alignment of the stellar rotation pole and the planet orbit normal. This spin-orbitmore » alignment can be used to constrain models of planet formation and evolution. Orderly planet formation and migration within a disk that is coplanar with the stellar equator will result in spin-orbit alignment. More violent planet-planet scattering events should yield spin-orbit misaligned planets. Rossiter-McLaughlin measurements of transits of lower-mass stars show that some planets are spin-orbit aligned, and some are not. Since Rossiter-McLaughlin measurements are difficult around rapid rotators, lightcurve photometry may be the best way to determine the spin-orbit alignment of planets around massive stars. The Kepler mission will monitor approx10{sup 4} of these stars within its sample. The lightcurves of any detected planets will allow us to probe the planet formation process around high-mass stars for the first time.« less

Large longitudinal spin alignment generated in inelastic nuclear reactions

NASA Astrophysics Data System (ADS)

Hoff, D. E. M.; Potel, G.; Brown, K. W.; Charity, R. J.; Pruitt, C. D.; Sobotka, L. G.; Webb, T. B.; Roeder, B.; Saastamoinen, A.

2018-05-01

Large longitudinal spin alignment of E /A =24 MeV 7Li projectiles inelastically excited by Be, C, and Al targets was observed when the latter remain in their ground state. This alignment is a consequence of an angular-momentum-excitation-energy mismatch, which is well described by a DWBA cluster-model (α +t ). The longitudinal alignment of several other systems is also well described by DWBA calculations, including one where a cluster model is inappropriate, demonstrating that the alignment mechanism is a more general phenomenon. Predictions are made for inelastic excitation of 12C for beam energies above and below the mismatch threshold.

The Consequences of Spin-Orbit Coupling on the 5d3 Electronic Configuration

NASA Astrophysics Data System (ADS)

Christianson, A. D.

The impact of spin-orbit coupling on collective properties of matter is of considerable interest. The most intensively investigated materials in this regard are Iridium-based transition metal oxides which exhibit a host of interesting ground states that originate from a 5d5 Jeff = 1/2 electronic configuration. Moving beyond the Jeff = 1/2 paradigm to other electronic configurations where spin-orbit coupling plays a prominent role is a key objective of ongoing research. Here we focus on several Osmium-based transition metal oxides such as NaOsO3, Cd2Os2O7, Ca3LiOsO6, Sr2ScOsO6, Ba2YOsO6, and Sr2FeOsO6, which are nominally in the 5d3 electronic configuration. Within the LS coupling picture and a strong octahedral crystal field, the 5d3 configuration is expected to be an orbital singlet and spin-orbit effects should be minimal. Nevertheless, our neutron and x-ray scattering investigations of these materials as well as investigations by other groups show dramatic effects of spin-orbit coupling including reduced moment magnetic order, enhanced spin-phonon coupling, and large spin gaps. In particular, the anisotropy induced by spin-orbit coupling tips the balance of the frustrated interactions and drives the selection of particular magnetic ground states. To understand the mechanism driving the spin-orbit effects, we have explored the ground state t2g manifold with resonant inelastic x-ray scattering and observe a spectrum inexplicable by an LS coupling picture. On the other hand, an intermediate coupling approach reveals that the ground state wave function is a J =3/2 configuration which answers the question of how strong spin-orbit coupling effects arise in 5d3 systems.

Innermost stable circular orbit of spinning particle in charged spinning black hole background

NASA Astrophysics Data System (ADS)

Zhang, Yu-Peng; Wei, Shao-Wen; Guo, Wen-Di; Sui, Tao-Tao; Liu, Yu-Xiao

2018-04-01

In this paper we investigate the innermost stable circular orbit (ISCO) (spin-aligned or anti-aligned orbit) for a classical spinning test particle with the pole-dipole approximation in the background of Kerr-Newman black hole in the equatorial plane. It is shown that the orbit of the spinning particle is related to the spin of the test particle. The motion of the spinning test particle will be superluminal if its spin is too large. We give an additional condition by considering the superluminal constraint for the ISCO in the black hole backgrounds. We obtain numerically the relations between the ISCO and the properties of the black holes and the test particle. It is found that the radius of the ISCO for a spinning test particle is smaller than that of a nonspinning test particle in the black hole backgrounds.

Effects of discontinuous drooped wing leading-edge modifications on the spinning characteristics of a low-wing general aviation airplane

NASA Technical Reports Server (NTRS)

Dicarlo, D. J.; Stough, H. P., III; Patton, J. M., Jr.

1980-01-01

Wind tunnel and flight tests were conducted to determine the effects of several discontinuous drooped wing leading-edge configurations on the spinning characteristics of a light, single-engine, low-wing research airplane. Particular emphasis was placed on the identification of modifications which would improve the spinning characteristics. The spanwise length of a discontinuous outboard droop was varied and several additional inboard segments were added to determine the influence of such leading-edge configurations on the spin behavior. Results of the study indicated that the use of only the discontinuous outboard droop, over a specific spanwise area, was most effective towards improving spin and spin recovery characteristics, whereas the segmented configurations having both inboard and outboard droop exhibited a tendency to enter a flat spin.

Strangeness spin, magnetic moment, and strangeness configurations of the proton

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, C.S.; Riska, D.O.; Zou, B.S.

2006-03-15

The implications of the empirical signatures for the positivity of the strangeness magnetic moment {mu}{sub s} and the negativity of the strangeness contribution to the proton spin {delta}{sub s} on the possible uudss configurations of five quarks in the proton are analyzed. The empirical signs for the values for these two observables can only be obtained in configurations where the uuds subsystem is orbitally excited and the s antiquark is in the ground state. The configurations in which the s is orbitally excited, including the conventional K{sup +}{lambda}{sup 0} configuration, with the exception of that in which the uuds componentmore » has spin 2, yield negative values for {mu}{sub s}. Here, the strangeness spin {delta}{sub s}, strangeness magnetic moment {mu}{sub s}, and axial coupling constant G{sub A}{sup s} are calculated for all possible configurations of the uudss component of the proton. In the configuration with [4]{sub FS}[22]{sub F}[22]{sub S} flavor-spin symmetry, which is likely to have the lowest energy, {mu}{sub s} is positive and {delta}{sub s}{approx_equal}G{sub A}{sup s}{approx_equal}-1/3{mu}{sub s}.« less

Accuracy of binary black hole waveform models for aligned-spin binaries

NASA Astrophysics Data System (ADS)

Kumar, Prayush; Chu, Tony; Fong, Heather; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela

2016-05-01

Coalescing binary black holes are among the primary science targets for second generation ground-based gravitational wave detectors. Reliable gravitational waveform models are central to detection of such systems and subsequent parameter estimation. This paper performs a comprehensive analysis of the accuracy of recent waveform models for binary black holes with aligned spins, utilizing a new set of 84 high-accuracy numerical relativity simulations. Our analysis covers comparable mass binaries (mass-ratio 1 ≤q ≤3 ), and samples independently both black hole spins up to a dimensionless spin magnitude of 0.9 for equal-mass binaries and 0.85 for unequal mass binaries. Furthermore, we focus on the high-mass regime (total mass ≳50 M⊙ ). The two most recent waveform models considered (PhenomD and SEOBNRv2) both perform very well for signal detection, losing less than 0.5% of the recoverable signal-to-noise ratio ρ , except that SEOBNRv2's efficiency drops slightly for both black hole spins aligned at large magnitude. For parameter estimation, modeling inaccuracies of the SEOBNRv2 model are found to be smaller than systematic uncertainties for moderately strong GW events up to roughly ρ ≲15 . PhenomD's modeling errors are found to be smaller than SEOBNRv2's, and are generally irrelevant for ρ ≲20 . Both models' accuracy deteriorates with increased mass ratio, and when at least one black hole spin is large and aligned. The SEOBNRv2 model shows a pronounced disagreement with the numerical relativity simulation in the merger phase, for unequal masses and simultaneously both black hole spins very large and aligned. Two older waveform models (PhenomC and SEOBNRv1) are found to be distinctly less accurate than the more recent PhenomD and SEOBNRv2 models. Finally, we quantify the bias expected from all four waveform models during parameter estimation for several recovered binary parameters: chirp mass, mass ratio, and effective spin.

Zinc-blende MnN bilayer formation on the GaN(111) surface

NASA Astrophysics Data System (ADS)

Gutierrez-Ojeda, S. J.; Guerrero-Sánchez, J.; Garcia-Diaz, R.; Ramirez-Torres, A.; Takeuchi, Noboru; H. Cocoletzi, Gregorio

2017-07-01

Atomic layers of manganese nitride, deposited on the cubic gallium nitride (111) surface, are investigated using spin polarized periodic density functional theory calculations. The adsorption of a manganese atom has been evaluated at different high symmetry sites. Incorporation into the GaN substrate by replacing gallium atoms drives the formation of a site in which the displaced Ga atom forms bonds with Ga atoms at the surface. This energetically favorable configuration shows a ferromagnetic alignment. Surface formation energy calculations demonstrate that when a full Mn ML is incorporated into the GaN structure, a Ga ML on top of a MnN bilayer may be formed for very Ga-rich conditions. On the other hand, when a full Mn ML is deposited on top of the nitrogen terminated surface, an epitaxial MnN bilayer is formed with antiferromagnetic characteristics. Density of states and partial density of states are reported to show the antiferromagnetic alignment in both structures. This behavior is mainly induced by the Mn-d orbitals.

The SOAPS project - Spin-orbit alignment of planetary systems. Exoplanets' evolution histories in systems with different architectures

NASA Astrophysics Data System (ADS)

Faedi, F.; Gómez Maqueo Chew, Y.; Fossati, L.; Pollacco, D.; McQuillan, A.; Hebb, L.; Chaplin, W. J.; Aigrain, S.

2013-04-01

The wealth of information rendered by Kepler planets and planet candidates is indispensable for statistically significant studies of distinct planet populations, in both single and multiple systems. Empirical evidences suggest that Kepler's planet population shows different physical properties as compared to the bulk of known exoplanets. The SOAPS project, aims to shed light on Kepler's planets formation, their migration and architecture. By measuring v sini accurately for Kepler hosts with rotation periods measured from their high-precision light curves, we will assess the alignment of the planetary orbit with respect to the stellar spin axis. This degree of alignment traces the formation history and evolution of the planetary systems, and thus, allows to distinguish between different proposed migration theories. SOAPS will increase by a factor of 2 the number of spin-orbit alignment measurements pushing the parameters space down to the SuperEarth domain. Here we present our preliminary results.

Electromagnetic versus Lense-Thirring alignment of black hole accretion discs

NASA Astrophysics Data System (ADS)

Polko, Peter; McKinney, Jonathan C.

2017-01-01

Accretion discs and black holes (BHs) have angular momenta that are generally misaligned, which can lead to warped discs and bends in any jets produced. We examine whether a disc that is misaligned at large radii can be aligned more efficiently by the torque of a Blandford-Znajek (BZ) jet than by Lense-Thirring (LT) precession. To obtain a strong result, we will assume that these torques maximally align the disc, rather than cause precession, or disc tearing. We consider several disc states that include radiatively inefficient thick discs, radiatively efficient thin discs, and super-Eddington accretion discs. The magnetic field strength of the BZ jet is chosen as either from standard equipartition arguments or from magnetically arrested disc (MAD) simulations. We show that standard thin accretion discs can reach spin-disc alignment out to large radii long before LT would play a role, due to the slow infall time that gives even a weak BZ jet time to align the disc. We show that geometrically thick radiatively inefficient discs and super-Eddington discs in the MAD state reach spin-disc alignment near the BH when density profiles are shallow as in magnetohydrodynamical simulations, while the BZ jet aligns discs with steep density profiles (as in advection-dominated accretion flows) out to larger radii. Our results imply that the BZ jet torque should affect the cosmological evolution of BH spin magnitude and direction, spin measurements in active galactic nuclei and X-ray binaries, and the interpretations for Event Horizon Telescope observations of discs or jets in strong-field gravity regimes.

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bawaj, M.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, H.-P.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Deelman, E.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devenson, J.; Devine, R. C.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Duncan, J.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gabel, M.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garufi, F.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Johnson-McDaniel, N. K.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Liu, J.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mayani, R.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muniz, E. A. M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Nery, M.; Neunzert, A.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Ramirez, K. E.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Rynge, M.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheuer, J.; Schmidt, E.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson, S. P.; Stone, R.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Taylor, J. A.; Taylor, R.; Theeg, T.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahi, K.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Wald, R. M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, M.; Wang, Y.-F.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, Hang; Yu, Haocun; Yvert, M.; ZadroŻny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zimmerman, A.; Zucker, M. E.; Zweizig, J.; LIGO Scientific; Virgo Collaboration

2017-06-01

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31. 2-6.0+8.4M⊙ and 19. 4-5.9+5.3 M⊙ (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χeff=-0.1 2-0.30+0.21 . This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 88 0-390+450 Mpc corresponding to a redshift of z =0.1 8-0.07+0.08 . We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to mg≤7.7 ×10-23 eV /c2 . In all cases, we find that GW170104 is consistent with general relativity.

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2.

PubMed

Abbott, B P; Abbott, R; Abbott, T D; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Afrough, M; Agarwal, B; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allen, G; Allocca, A; Altin, P A; Amato, A; Ananyeva, A; Anderson, S B; Anderson, W G; Antier, S; Appert, S; Arai, K; Araya, M C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; AultONeal, K; Avila-Alvarez, A; Babak, S; Bacon, P; Bader, M K M; Bae, S; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Banagiri, S; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bawaj, M; Bazzan, M; Bécsy, B; Beer, C; Bejger, M; Belahcene, I; Bell, A S; Berger, B K; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Billman, C R; Birch, J; Birney, R; Birnholtz, O; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blackman, J; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Bode, N; Boer, M; Bogaert, G; Bohe, A; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Broida, J E; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Brunett, S; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cabero, M; Cadonati, L; Cagnoli, G; Cahillane, C; Calderón Bustillo, J; Callister, T A; Calloni, E; Camp, J B; Canepa, M; Canizares, P; Cannon, K C; Cao, H; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Carney, M F; Casanueva Diaz, J; Casentini, C; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Cerboni Baiardi, L; Cerretani, G; Cesarini, E; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Chatterjee, D; Chatziioannou, K; Cheeseboro, B D; Chen, H Y; Chen, Y; Cheng, H-P; Chincarini, A; Chiummo, A; Chmiel, T; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, A J K; Chua, S; Chung, A K W; Chung, S; Ciani, G; Ciolfi, R; Cirelli, C E; Cirone, A; Clara, F; Clark, J A; Cleva, F; Cocchieri, C; Coccia, E; Cohadon, P-F; Colla, A; Collette, C G; Cominsky, L R; Constancio, M; Conti, L; Cooper, S J; Corban, P; Corbitt, T R; Corley, K R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J-P; Countryman, S T; Couvares, P; Covas, P B; Cowan, E E; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Creighton, J D E; Creighton, T D; Cripe, J; Crowder, S G; Cullen, T J; Cumming, A; Cunningham, L; Cuoco, E; Dal Canton, T; Danilishin, S L; D'Antonio, S; Danzmann, K; Dasgupta, A; Da Silva Costa, C F; Dattilo, V; Dave, I; Davier, M; Davis, D; Daw, E J; Day, B; De, S; DeBra, D; Deelman, E; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Devenson, J; Devine, R C; Dhurandhar, S; Díaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Renzo, F; Doctor, Z; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Dorrington, I; Douglas, R; Dovale Álvarez, M; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Duncan, J; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Eisenstein, R A; Essick, R C; Etienne, Z B; Etzel, T; Evans, M; Evans, T M; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Farinon, S; Farr, B; Farr, W M; Fauchon-Jones, E J; Favata, M; Fays, M; Fehrmann, H; Feicht, J; Fejer, M M; Fernandez-Galiana, A; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fong, H; Forsyth, P W F; Forsyth, S S; Fournier, J-D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fries, E M; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H; Gabel, M; Gadre, B U; Gaebel, S M; Gair, J R; Gammaitoni, L; Ganija, M R; Gaonkar, S G; Garufi, F; Gaudio, S; Gaur, G; Gayathri, V; Gehrels, N; Gemme, G; Genin, E; Gennai, A; George, D; George, J; Gergely, L; Germain, V; Ghonge, S; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glover, L; Goetz, E; Goetz, R; Gomes, S; González, G; Gonzalez Castro, J M; Gopakumar, A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Gruning, P; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hannuksela, O A; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Haster, C-J; Haughian, K; Healy, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Henry, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hofman, D; Holt, K; Holz, D E; Hopkins, P; Horst, C; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Indik, N; Ingram, D R; Inta, R; Intini, G; Isa, H N; Isac, J-M; Isi, M; Iyer, B R; Izumi, K; Jacqmin, T; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Johnson-McDaniel, N K; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Junker, J; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Karvinen, K S; Kasprzack, M; Katolik, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kawabe, K; Kéfélian, F; Keitel, D; Kemball, A J; Kennedy, R; Kent, C; Key, J S; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chunglee; Kim, J C; Kim, W; Kim, W S; Kim, Y-M; Kimbrell, S J; King, E J; King, P J; Kirchhoff, R; Kissel, J S; Kleybolte, L; Klimenko, S; Koch, P; Koehlenbeck, S M; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Krämer, C; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, P; Kumar, R; Kumar, S; Kuo, L; Kutynia, A; Kwang, S; Lackey, B D; Lai, K H; Landry, M; Lang, R N; Lange, J; Lantz, B; Lanza, R K; Lartaux-Vollard, A; Lasky, P D; Laxen, M; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lee, C H; Lee, H K; Lee, H M; Lee, H W; Lee, K; Lehmann, J; Lenon, A; Leonardi, M; Leroy, N; Letendre, N; Levin, Y; Li, T G F; Libson, A; Littenberg, T B; Liu, J; Lo, R K L; Lockerbie, N A; London, L T; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lovelace, G; Lück, H; Lumaca, D; Lundgren, A P; Lynch, R; Ma, Y; Macfoy, S; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña Hernandez, I; Magaña-Sandoval, F; Magaña Zertuche, L; Magee, R M; Majorana, E; Maksimovic, I; Man, N; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markakis, C; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matas, A; Matichard, F; Matone, L; Mavalvala, N; Mayani, R; Mazumder, N; McCarthy, R; McClelland, D E; McCormick, S; McCuller, L; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McRae, T; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Mejuto-Villa, E; Melatos, A; Mendell, G; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, A; Miller, B B; Miller, J; Millhouse, M; Minazzoli, O; Minenkov, Y; Ming, J; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mours, B; Mow-Lowry, C M; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, N; Mullavey, A; Munch, J; Muniz, E A M; Murray, P G; Napier, K; Nardecchia, I; Naticchioni, L; Nayak, R K; Nelemans, G; Nelson, T J N; Neri, M; Nery, M; Neunzert, A; Newport, J M; Newton, G; Ng, K K Y; Nguyen, T T; Nichols, D; Nielsen, A B; Nissanke, S; Nitz, A; Noack, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; Ormiston, R; Ortega, L F; O'Shaughnessy, R; Ottaway, D J; Overmier, H; Owen, B J; Pace, A E; Page, J; Page, M A; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pang, B; Pang, P T H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Perez, C J; Perreca, A; Perri, L M; Pfeiffer, H P; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poggiani, R; Popolizio, P; Porter, E K; Post, A; Powell, J; Prasad, J; Pratt, J W W; Predoi, V; Prestegard, T; Prijatelj, M; Principe, M; Privitera, S; Prodi, G A; Prokhorov, L G; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Qiu, S; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rajan, C; Rakhmanov, M; Ramirez, K E; Rapagnani, P; Raymond, V; Razzano, M; Read, J; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Reyes, S D; Ricci, F; Ricker, P M; Rieger, S; Riles, K; Rizzo, M; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romel, C L; Romie, J H; Rosińska, D; Ross, M P; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Rynge, M; Sachdev, S; Sadecki, T; Sadeghian, L; Sakellariadou, M; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sampson, L M; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O; Savage, R L; Sawadsky, A; Schale, P; Scheuer, J; Schmidt, E; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schulte, B W; Schutz, B F; Schwalbe, S G; Scott, J; Scott, S M; Seidel, E; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D A; Shaffer, T J; Shah, A A; Shahriar, M S; Shao, L; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, B; Smith, J R; Smith, R J E; Son, E J; Sonnenberg, J A; Sorazu, B; Sorrentino, F; Souradeep, T; Spencer, A P; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stevenson, S P; Stone, R; Strain, K A; Stratta, G; Strigin, S E; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sunil, S; Sutton, P J; Swinkels, B L; Szczepańczyk, M J; Tacca, M; Talukder, D; Tanner, D B; Tápai, M; Taracchini, A; Taylor, J A; Taylor, R; Theeg, T; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Toland, K; Tonelli, M; Tornasi, Z; Torrie, C I; Töyrä, D; Travasso, F; Traylor, G; Trifirò, D; Trinastic, J; Tringali, M C; Trozzo, L; Tsang, K W; Tse, M; Tso, R; Tuyenbayev, D; Ueno, K; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahi, K; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Bakel, N; van Beuzekom, M; van den Brand, J F J; Van Den Broeck, C; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Varma, V; Vass, S; Vasúth, M; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Venugopalan, G; Verkindt, D; Vetrano, F; Viceré, A; Viets, A D; Vinciguerra, S; Vine, D J; Vinet, J-Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Wald, R M; Walet, R; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, J Z; Wang, M; Wang, Y-F; Wang, Y; Ward, R L; Warner, J; Was, M; Watchi, J; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Wen, L; Wessel, E K; Weßels, P; Westphal, T; Wette, K; Whelan, J T; Whiting, B F; Whittle, C; Williams, D; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Woehler, J; Wofford, J; Wong, K W K; Worden, J; Wright, J L; Wu, D S; Wu, G; Yam, W; Yamamoto, H; Yancey, C C; Yap, M J; Yu, Hang; Yu, Haocun; Yvert, M; Zadrożny, A; Zanolin, M; Zelenova, T; Zendri, J-P; Zevin, M; Zhang, L; Zhang, M; Zhang, T; Zhang, Y-H; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zimmerman, A; Zucker, M E; Zweizig, J

2017-06-02

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2_{-6.0}^{+8.4}M_{⊙} and 19.4_{-5.9}^{+5.3}M_{⊙} (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χ_{eff}=-0.12_{-0.30}^{+0.21}. This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880_{-390}^{+450}  Mpc corresponding to a redshift of z=0.18_{-0.07}^{+0.08}. We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m_{g}≤7.7×10^{-23}  eV/c^{2}. In all cases, we find that GW170104 is consistent with general relativity.

CFD Prediction for Spin Rate of Fixed Canards on a Spinning Projectile

NASA Astrophysics Data System (ADS)

Ji, X. L.; Jia, Ch. Y.; Jiang, T. Y.

2011-09-01

A computational study performed for spin rate of fixed canards on a spinning projectile is presented in this paper. The cancards configurations provide challenges in terms of the determination of the aerodynamic forces and moments and the flow field changes which could have significant effect on the stability, performance, and corrected round accuracy. Advanced time accurate Navier-Stokes computations have been performed to compute the spin rate associated with the spinning motion of the cancards configurations at supersonic speed. The results show that roll-damping moment of cancards varies linearly with the spin rate at supersonic velocity.

Using Spin to Understand the Formation of LIGO and Virgo’s Black Holes

NASA Astrophysics Data System (ADS)

Farr, Ben; Holz, Daniel E.; Farr, Will M.

2018-02-01

With the growing number of binary black hole (BBH) mergers detected by the Advanced LIGO and Virgo detectors, it is becoming possible to constrain the properties of the underlying population and better understand the formation of these systems. Black hole (BH) spin orientations are one of the cleanest discriminators of formation history, with BHs in dynamically formed binaries in dense stellar environments expected to have spins distributed isotropically, in contrast to isolated populations where stellar evolution is expected to induce spins preferentially aligned with the orbital angular momentum. In this work, we propose a simple, model-agnostic approach to characterizing the spin properties of LIGO/Virgo’s BBH population. Using measurements of the effective spin of the binaries, we introduce a simple parameter to quantify the fraction of the population that is isotropically distributed, regardless of the spin magnitude distribution of the population. Once the orientation characteristics of the population have been determined, we show how measurements of effective spin can be used to directly constrain the BH spin magnitude distribution. We find that most effective spin measurements are too small to be informative, with the first four events showing a slight preference for a population with alignment, with an odds ratio of 1.2. We argue that it will be possible to distinguish symmetric and anti-symmetric populations at high confidence with tens of additional detections, although mixed populations may take significantly longer to disentangle. We also derive BH spin magnitude distributions from LIGO’s first four BBHs under the assumption of aligned or isotropic populations.

Controllable spin polarization and spin filtering in a zigzag silicene nanoribbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farokhnezhad, Mohsen, E-mail: Mohsen-farokhnezhad@physics.iust.ac.ir; Esmaeilzadeh, Mahdi, E-mail: mahdi@iust.ac.ir; Pournaghavi, Nezhat

2015-05-07

Using non-equilibrium Green's function, we study the spin-dependent electron transport properties in a zigzag silicene nanoribbon. To produce and control spin polarization, it is assumed that two ferromagnetic strips are deposited on the both edges of the silicene nanoribbon and an electric field is perpendicularly applied to the nanoribbon plane. The spin polarization is studied for both parallel and anti-parallel configurations of exchange magnetic fields induced by the ferromagnetic strips. We find that complete spin polarization can take place in the presence of perpendicular electric field for anti-parallel configuration and the nanoribbon can work as a perfect spin filter. Themore » spin direction of transmitted electrons can be easily changed from up to down and vice versa by reversing the electric field direction. For parallel configuration, perfect spin filtering can occur even in the absence of electric field. In this case, the spin direction can be changed by changing the electron energy. Finally, we investigate the effects of nonmagnetic Anderson disorder on spin dependent conductance and find that the perfect spin filtering properties of nanoribbon are destroyed by strong disorder, but the nanoribbon retains these properties in the presence of weak disorder.« less

Dancing in the dark: galactic properties trace spin swings along the cosmic web

NASA Astrophysics Data System (ADS)

Dubois, Y.; Pichon, C.; Welker, C.; Le Borgne, D.; Devriendt, J.; Laigle, C.; Codis, S.; Pogosyan, D.; Arnouts, S.; Benabed, K.; Bertin, E.; Blaizot, J.; Bouchet, F.; Cardoso, J.-F.; Colombi, S.; de Lapparent, V.; Desjacques, V.; Gavazzi, R.; Kassin, S.; Kimm, T.; McCracken, H.; Milliard, B.; Peirani, S.; Prunet, S.; Rouberol, S.; Silk, J.; Slyz, A.; Sousbie, T.; Teyssier, R.; Tresse, L.; Treyer, M.; Vibert, D.; Volonteri, M.

2014-10-01

A large-scale hydrodynamical cosmological simulation, Horizon-AGN, is used to investigate the alignment between the spin of galaxies and the cosmic filaments above redshift 1.2. The analysis of more than 150 000 galaxies per time step in the redshift range 1.2 < z < 1.8 with morphological diversity shows that the spin of low-mass blue galaxies is preferentially aligned with their neighbouring filaments, while high-mass red galaxies tend to have a perpendicular spin. The reorientation of the spin of massive galaxies is provided by galaxy mergers, which are significant in their mass build-up. We find that the stellar mass transition from alignment to misalignment happens around 3 × 1010 M⊙. Galaxies form in the vorticity-rich neighbourhood of filaments, and migrate towards the nodes of the cosmic web as they convert their orbital angular momentum into spin. The signature of this process can be traced to the properties of galaxies, as measured relative to the cosmic web. We argue that a strong source of feedback such as active galactic nuclei is mandatory to quench in situ star formation in massive galaxies and promote various morphologies. It allows mergers to play their key role by reducing post-merger gas inflows and, therefore, keeping spins misaligned with cosmic filaments.

Magnetic moment of the fragmentation-aligned 61Fe (9/2(+)) isomer.

PubMed

Matea, I; Georgiev, G; Daugas, J M; Hass, M; Neyens, G; Astabatyan, R; Baby, L T; Balabanski, D L; Bélier, G; Borremans, D; Goldring, G; Goutte, H; Himpe, P; Lewitowicz, M; Lukyanov, S; Méot, V; Santos, F de Oliveira; Penionzhkevich, Yu E; Roig, O; Sawicka, M

2004-10-01

We report on the g factor measurement of an isomer in the neutron-rich (61)(26)Fe (E(*)=861 keV and T(1/2)=239(5) ns). The isomer was produced and spin aligned via a projectile-fragmentation reaction at intermediate energy, the time dependent perturbed angular distribution method being used for the measurement of the g factor. For the first time, due to significant improvements of the experimental technique, an appreciable residual alignment of the nuclear spin ensemble has been observed, allowing a precise determination of its g factor, including the sign: g=-0.229(2). In this way we open the possibility to study moments of very neutron-rich short-lived isomers, not accessible via other production and spin-orientation methods.

How do external companions affect spin-orbit misalignment of hot Jupiters?

NASA Astrophysics Data System (ADS)

Lai, Dong; Anderson, Kassandra R.; Pu, Bonan

2018-04-01

Consider a planet with its orbital angular momentum axis aligned with the spin axis of its host star. To what extent does an inclined distant companion (giant planet or binary star) affect this alignment? We provide an analytic, quantitative answer and apply it to hot Jupiter systems, for which misalignments between the orbital axis and the stellar spin axis have been detected. We also show how similar consideration can be applied to multiplanet systems with distant companions (such as Kepler-56). The result of this paper provides a simple method to assess the dynamical role played by external companions on spin-orbit misalignments in exoplanetary systems.

Equation-of-motion coupled-cluster method for ionised states with spin-orbit coupling using open-shell reference wavefunction

NASA Astrophysics Data System (ADS)

Wang, Zhifan; Wang, Fan

2018-04-01

The equation-of-motion coupled-cluster method for ionised states at the singles and doubles level (EOM-IP-CCSD) with spin-orbit coupling (SOC) included in post-Hartree-Fock (HF) steps is extended to spatially non-degenerate open-shell systems such as high spin states of s1, p3, σ1 or π2 configuration in this work. Pseudopotentials are employed to treat relativistic effects and spin-unrestricted scalar relativistic HF determinant is adopted as reference in calculations. Symmetry is not exploited in the implementation since both time-reversal and spatial symmetry is broken due to SOC. IPs with the EOM-IP-CCSD approach are those from the 3Σ1- states for high spin state of π2 configuration, while the ground state is the 3Σ0- state. When removing an electron from the high spin state of p3 configuration, only the 3P2 state can be reached. The open-shell EOM-IP-CCSD approach with SOC was employed in calculating IPs of some open-shell atoms with s1 configuration, diatomic molecules with π2 configuration and SOC splitting of the ionised π1 state, as well as IPs of VA atoms with p3 configuration. Our results demonstrate that this approach can be applied to ionised states of spatially non-degenerate open-shell states containing heavy elements with reasonable accuracy.

X-ray microprobe of orbital alignment in strong-field ionized atoms.

PubMed

Young, L; Arms, D A; Dufresne, E M; Dunford, R W; Ederer, D L; Höhr, C; Kanter, E P; Krässig, B; Landahl, E C; Peterson, E R; Rudati, J; Santra, R; Southworth, S H

2006-08-25

We have developed a synchrotron-based, time-resolved x-ray microprobe to investigate optical strong-field processes at intermediate intensities (10(14) - 10(15) W/cm2). This quantum-state specific probe has enabled the direct observation of orbital alignment in the residual ion produced by strong-field ionization of krypton atoms via resonant, polarized x-ray absorption. We found strong alignment to persist for a period long compared to the spin-orbit coupling time scale (6.2 fs). The observed degree of alignment can be explained by models that incorporate spin-orbit coupling. The methodology is applicable to a wide range of problems.

Two spinning ways for precession dynamo.

PubMed

Cappanera, L; Guermond, J-L; Léorat, J; Nore, C

2016-04-01

It is numerically demonstrated by means of a magnetohydrodynamic code that precession can trigger dynamo action in a cylindrical container. Fixing the angle between the spin and the precession axis to be 1/2π, two limit configurations of the spinning axis are explored: either the symmetry axis of the cylinder is parallel to the spin axis (this configuration is henceforth referred to as the axial spin case), or it is perpendicular to the spin axis (this configuration is referred to as the equatorial spin case). In both cases, the centro-symmetry of the flow breaks when the kinetic Reynolds number increases. Equatorial spinning is found to be more efficient in breaking the centro-symmetry of the flow. In both cases, the average flow in the reference frame of the mantle converges to a counter-rotation with respect to the spin axis as the Reynolds number grows. We find a scaling law for the average kinetic energy in term of the Reynolds number in the axial spin case. In the equatorial spin case, the unsteady asymmetric flow is shown to be capable of sustaining dynamo action in the linear and nonlinear regimes. The magnetic field is mainly dipolar in the equatorial spin case, while it is is mainly quadrupolar in the axial spin case.

Complex magnetic structure of clusters and chains of Ni and Fe on Pt(111)

PubMed Central

Bezerra-Neto, Manoel M.; Ribeiro, Marcelo S.; Sanyal, Biplab; Bergman, Anders; Muniz, Roberto B.; Eriksson, Olle; Klautau, Angela B.

2013-01-01

We present an approach to control the magnetic structure of adatoms adsorbed on a substrate having a high magnetic susceptibility. Using finite Ni-Pt and Fe-Pt nanowires and nanostructures on Pt(111) surfaces, our ab initio results show that it is possible to tune the exchange interaction and magnetic configuration of magnetic adatoms (Fe or Ni) by introducing different numbers of Pt atoms to link them, or by including edge effects. The exchange interaction between Ni (or Fe) adatoms on Pt(111) can be considerably increased by introducing Pt chains to link them. The magnetic ordering can be regulated allowing for ferromagnetic or antiferromagnetic configurations. Noncollinear magnetic alignments can also be stabilized by changing the number of Pt-mediated atoms. An Fe-Pt triangularly-shaped nanostructure adsorbed on Pt(111) shows the most complex magnetic structure of the systems considered here: a spin-spiral type of magnetic order that changes its propagation direction at the triangle vertices. PMID:24165828

Spin-tunnel investigation of a 1/15-scale model of an Australian trainer airplane

NASA Technical Reports Server (NTRS)

Bowman, James S., Jr.; Whipple, Raymond D.; White, William L.

1987-01-01

An investigation was conducted in the Langley Spin Tunnel of the spin and spin-recovery characteristics of a 1/15-scale model of an Australian trainer airplane. The invesigation included erect and inverted spins; configuration variables such as a long tail, fuselage strakes, 20 deg. elevator cutouts, and rudder modifications; and determination of the parachute size for emergency spin recovery. Also included in the investigation were wing leading-edge modifications to evaluate Reynolds number effects. Results indicate that the basic configuration will spin erect at an angle of attack of about 63 deg. at about 2 to 2.3 seconds per turn. Recovery from this spin was unsatisfactory by rudder reversal or by rudder reversal and ailerons deflected to full with the spin. The elevators had a pronounced effect on the recovery characteristics. The elevators-down position was very adverse to recoveries, whereas the elevators-up position provided favorable recovery effects. Moving the vertical tail aft (producing a long tail configuration) improved the spin characteristics, but the recoveries were still considered marginal. An extension to the basic rudder chord and length made a significant improvement in the spin and recovery characteristics. Satisfactory recoveries were obtained by deflecting the rudder to full against the spin and the elevators and ailerons to neutral.

Understanding spin configuration in the geometrically frustrated magnet TbB 4: A resonant soft X-ray scattering study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.; Jang, H.; Kang, B. Y.

The frustrated magnet has been regarded as a system that could be a promising host material for the quantum spin liquid (QSL). However, it is difficult to determine the spin configuration and the corresponding mechanism in this system, because of its geometrical frustration ( i.e., crystal structure and symmetry). Herein, we systematically investigate one of the geometrically frustrated magnets, the TbB 4 compound. Using resonant soft x-ray scattering (RSXS), we explored its spin configuration, as well as Tb's quadrupole. Comprehensive evaluations of the temperature and photon energy/polarization dependences of the RSXS signals reveal the mechanism of spin reorientation upon coolingmore » down, which is the sophisticated interplay between the Tb spin and the crystal symmetry rather than its orbit (quadrupole). Here, our results and their implications would further shed a light on the search for possible realization of QSL.« less

Understanding spin configuration in the geometrically frustrated magnet TbB 4: A resonant soft X-ray scattering study

DOE PAGES

Huang, H.; Jang, H.; Kang, B. Y.; ...

2018-05-05

The frustrated magnet has been regarded as a system that could be a promising host material for the quantum spin liquid (QSL). However, it is difficult to determine the spin configuration and the corresponding mechanism in this system, because of its geometrical frustration ( i.e., crystal structure and symmetry). Herein, we systematically investigate one of the geometrically frustrated magnets, the TbB 4 compound. Using resonant soft x-ray scattering (RSXS), we explored its spin configuration, as well as Tb's quadrupole. Comprehensive evaluations of the temperature and photon energy/polarization dependences of the RSXS signals reveal the mechanism of spin reorientation upon coolingmore » down, which is the sophisticated interplay between the Tb spin and the crystal symmetry rather than its orbit (quadrupole). Here, our results and their implications would further shed a light on the search for possible realization of QSL.« less

On the Interpretation of the level structure of the Ground 3d5 Manifold of Mn III, Fe IV, Co V and Ni VI

NASA Astrophysics Data System (ADS)

Leushin, A. M.

2011-10-01

The level structure of the ground 3d5 configuration of Mn2+, Fe3+, Co4+ and Ni5+ ions was theoretically interpreted by means of a least-squares fit of the energy parameters to the observed values within the framework of the single-configuration approximation. In the Hamiltonian in addition to real electrostatic, spin-orbit, and spin-spin interactions, electrostatic and spin-orbit interactions correlated by configuration mixing were included. It was shown that the correct positions of almost all the energy levels are determined when the Hamiltonian includes the terms of the lineal (two-body operators) and nonlinear (three-body operators) theory of the configuration interaction. The most correct theoretical description of the experimental spectra was obtained by taking into account relativistic interactions and correlation effects of spin-orbit interactions. Adjustable parameters of the interactions included into the Hamiltonian were found.

Flow past an axially aligned spinning cylinder: Experimental Study

NASA Astrophysics Data System (ADS)

Carlucci, Pasquale; Buckley, Liam; Mehmedagic, Igbal; Carlucci, Donald; Thangam, Siva

2017-11-01

Experimental investigation of flow past a spinning cylinder is presented in the context of its application and relevance to flow past projectiles. A subsonic wind tunnel is used to perform experiments on the flow past a spinning cylinder that is mounted on a forward sting and oriented such that its axis of rotation is aligned with the mean flow. The experiments cover a Reynolds number of range of up to 45000 and rotation numbers of up to 2 (based on cylinder diameter). Time-averaged mean flow and turbulence profiles in the wake flow are presented with and without spin along with comparison to published experimental data. Funded in part by the U. S. Army ARDEC, Picatinny Arsenal, NJ.

Spin Polarized Transport in Multilayer Structures with Complex Magnetic Configurations

NASA Astrophysics Data System (ADS)

Sahakyan, Avag; Poghosyan, Anahit; Movsesyan, Ruzan; Kocharian, Armen

The spin transport and spin polarization in a new class of multilayer structures are investigated for non-collinear and noncoplanar magnetic configurations containing repetitive magnetic layers. The magnetic configuration of the structure dictates the existence of certain degrees of freedom that determines magnetic transport and polarization properties. We consider magnetic structures in magnetic multilayers with canted spin configurations separated by non-magnetic quantum well so that the exchange interaction between the neighbor barriers can be ignored. Configurations of magnetizations in barriers include some structures consisting of two ''ferromagnetic'' or ''antiferromagnetic'' domains twisted relative to each other by a certain angle (angle noncollinearity). The similar system, formed from two noncollinear domains separated by canted ''magnetic defect'' is also considered. The above mentioned properties of these systems depend strongly on the type of magnetic configuration and variation of certain degrees of freedom. Simple theoretical approach with the transfer matrix method is carried out to understand and predict the magnetic properties of the multilayer systems. The work at California University Los Angeles was supported by the National Science Foundation-Partnerships for Research and Education in Materials under Grant DMR-1523588.

Scalable alignment and transfer of nanowires in a Spinning Langmuir Film.

PubMed

Zhu, Ren; Lai, Yicong; Nguyen, Vu; Yang, Rusen

2014-10-21

Many nanomaterial-based integrated nanosystems require the assembly of nanowires and nanotubes into ordered arrays. A generic alignment method should be simple and fast for the proof-of-concept study by a researcher, and low-cost and scalable for mass production in industries. Here we have developed a novel Spinning-Langmuir-Film technique to fulfill both requirements. We used surfactant-enhanced shear flow to align inorganic and organic nanowires, which could be easily transferred to other substrates and ready for device fabrication in less than 20 minutes. The aligned nanowire areal density can be controlled in a wide range from 16/mm(-2) to 258/mm(-2), through the compression of the film. The surface surfactant layer significantly influences the quality of alignment and has been investigated in detail.

Why do galactic spins flip in the cosmic web? A Theory of Tidal Torques near saddles

NASA Astrophysics Data System (ADS)

Pichon, Christophe; Codis, Sandrine; Pogosyan, Dmitry; Dubois, Yohan; Desjacques, Vincent; Devriendt, Julien

2016-10-01

Filaments of the cosmic web drive spin acquisition of disc galaxies. The point process of filament-type saddle represent best this environment and can be used to revisit the Tidal Torque Theory in the context of an anisotropic peak (saddle) background split. The constrained misalignment between the tidal tensor and the Hessian of the density field generated in the vicinity of filament saddle points simply explains the corresponding transverse and longitudinal point-reflection symmetric geometry of spin distribution. It predicts in particular an azimuthal orientation of the spins of more massive galaxies and spin alignment with the filament for less massive galaxies. Its scale dependence also allows us to relate the transition mass corresponding to the alignment of dark matter halos' spin relative to the direction of their neighboring filament to this geometry, and to predict accordingly it's scaling with the mass of non linearity, as was measured in simulations.

Tuning the Spin-Alignment of Interstitial Electrons in Two-Dimensional Y2C Electride via Chemical Pressure.

PubMed

Park, Jongho; Hwang, Jae-Yeol; Lee, Kyu Hyoung; Kim, Seong-Gon; Lee, Kimoon; Kim, Sung Wng

2017-12-06

We report that the spin-alignment of interstitial anionic electrons (IAEs) in two-dimensional (2D) interlayer spacing can be tuned by chemical pressure that controls the magnetic properties of 2D electrides. It was clarified from the isovalent Sc substitution on the Y site in the 2D Y 2 C electride that the localization degree of IAEs at the interlayer becomes stronger as the unit cell volume and c-axis lattice parameter were systematically reduced by increasing the Sc contents, thus eventually enhancing superparamagnetic behavior originated from the increase in ferromagnetic particle concentration. It was also found that the spin-aligned localized IAEs dominated the electrical conduction of heavily Sc-substituted Y 2 C electride. These results indicate that the physcial properties of 2D electrides can be tailored by adjusting the localization of IAEs at interlayer spacing via structural modification that controls the spin instability as found in three-dimensional elemental electrides of pressurized potassium metals.

Scalable quantum computer architecture with coupled donor-quantum dot qubits

DOEpatents

Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

2014-08-26

A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

Absence of high-temperature ballistic transport in the spin-1/2 XXX chain within the grand-canonical ensemble

NASA Astrophysics Data System (ADS)

Carmelo, J. M. P.; Prosen, T.

2017-01-01

Whether in the thermodynamic limit, vanishing magnetic field h → 0, and nonzero temperature the spin stiffness of the spin-1/2 XXX Heisenberg chain is finite or vanishes within the grand-canonical ensemble remains an unsolved and controversial issue, as different approaches yield contradictory results. Here we provide an upper bound on the stiffness and show that within that ensemble it vanishes for h → 0 in the thermodynamic limit of chain length L → ∞, at high temperatures T → ∞. Our approach uses a representation in terms of the L physical spins 1/2. For all configurations that generate the exact spin-S energy and momentum eigenstates such a configuration involves a number 2S of unpaired spins 1/2 in multiplet configurations and L - 2 S spins 1/2 that are paired within Msp = L / 2 - S spin-singlet pairs. The Bethe-ansatz strings of length n = 1 and n > 1 describe a single unbound spin-singlet pair and a configuration within which n pairs are bound, respectively. In the case of n > 1 pairs this holds both for ideal and deformed strings associated with n complex rapidities with the same real part. The use of such a spin 1/2 representation provides useful physical information on the problem under investigation in contrast to often less controllable numerical studies. Our results provide strong evidence for the absence of ballistic transport in the spin-1/2 XXX Heisenberg chain in the thermodynamic limit, for high temperatures T → ∞, vanishing magnetic field h → 0 and within the grand-canonical ensemble.

Quantifying selective alignment of ensemble nitrogen-vacancy centers in (111) diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tahara, Kosuke; Ozawa, Hayato; Iwasaki, Takayuki

2015-11-09

Selective alignment of nitrogen-vacancy (NV) centers in diamond is an important technique towards its applications. Quantification of the alignment ratio is necessary to design the optimized diamond samples. However, this is not a straightforward problem for dense ensemble of the NV centers. We estimate the alignment ratio of ensemble NV centers along the [111] direction in (111) diamond by optically detected magnetic resonance measurements. Diamond films deposited by N{sub 2} doped chemical vapor deposition have NV center densities over 1 × 10{sup 15 }cm{sup −3} and alignment ratios over 75%. Although spin coherence time (T{sub 2}) is limited to a few μs bymore » electron spins of nitrogen impurities, the combination of the selective alignment and the high density can be a possible way to optimize NV-containing diamond samples for the sensing applications.« less

Driving spin transition at interface: Role of adsorption configurations

NASA Astrophysics Data System (ADS)

Zhang, Yachao

2018-01-01

A clear insight into the electrical manipulation of molecular spins at interface is crucial to the design of molecule-based spintronic devices. Here we report on the electrically driven spin transition in manganocene physisorbed on a metallic surface in two different adsorption configurations predicted by ab initio techniques, including a Hubbard-U correction at the manganese site and accounting for the long-range van der Waals interactions. We show that the application of an electric field at the interface induces a high-spin to low-spin transition in the flat-lying manganocene, while it could hardly alter the high-spin ground state of the standing-up molecule. This phenomenon cannot be explained by either the molecule-metal charge transfer or the local electron correlation effects. We demonstrate a linear dependence of the intra-molecular spin-state splitting on the energy difference between crystal-field splitting and on-site Coulomb repulsion. After considering the molecule-surface binding energy shifts upon spin transition, we reproduce the obtained spin-state energetics. We find that the configuration-dependent responses of the spin-transition originate from the binding energy shifts instead of the variation of the local ligand field. Through these analyses, we obtain an intuitive understanding of the effects of molecule-surface contact on spin-crossover under electrical bias.

The effect of engine spin direction on the dynamics of powered two wheelers

NASA Astrophysics Data System (ADS)

Massaro, Matteo; Marconi, Edoardo

2018-04-01

The effect of engine spin direction on the dynamics of powered two wheelers is investigated in terms of steady-state points (equilibria), vibration modes (stability), manoeuvre time (performance/manoeuvrability) and handling. The goal is to assess and quantify the advantage sometimes claimed for the 'counter-rotating' engine configuration, where the engine spins in the opposite direction with respect to wheels, against the 'conventional' configuration, where the engine spins in the same direction of wheels.

Extrinsic Rashba spin-orbit coupling effect on silicene spin polarized field effect transistors

NASA Astrophysics Data System (ADS)

Pournaghavi, Nezhat; Esmaeilzadeh, Mahdi; Abrishamifar, Adib; Ahmadi, Somaieh

2017-04-01

Regarding the spin field effect transistor (spin FET) challenges such as mismatch effect in spin injection and insufficient spin life time, we propose a silicene based device which can be a promising candidate to overcome some of those problems. Using non-equilibrium Green’s function method, we investigate the spin-dependent conductance in a zigzag silicene nanoribbon connected to two magnetized leads which are supposed to be either in parallel or anti-parallel configurations. For both configurations, a controllable spin current can be obtained when the Rashba effect is present; thus, we can have a spin filter device. In addition, for anti-parallel configuration, in the absence of Rashba effect, there is an intrinsic energy gap in the system (OFF-state); while, in the presence of Rashba effect, electrons with flipped spin can pass through the channel and make the ON-state. The current voltage (I-V) characteristics which can be tuned by changing the gate voltage or Rashba strength, are studied. More importantly, reducing the mismatch conductivity as well as energy consumption make the silicene based spin FET more efficient relative to the spin FET based on two-dimensional electron gas proposed by Datta and Das. Also, we show that, at the same conditions, the current and {{I}\\text{on}}/{{I}\\text{off}} ratio of silicene based spin FET are significantly greater than that of the graphene based one.

Wet-spinning fabrication of shear-patterned alginate hydrogel microfibers and the guidance of cell alignment

PubMed Central

Yang, You; Sun, Jing; Liu, Xiaolu; Guo, Zhenzhen; He, Yunhu; Wei, Dan; Zhong, Meiling; Guo, Likun; Zhang, Xingdong

2017-01-01

Abstract Native tissue is naturally comprised of highly-ordered cell-matrix assemblies in a multi-hierarchical way, and the nano/submicron alignment of fibrous matrix is found to be significant in supporting cellular functionalization. In this study, a self-designed wet-spinning device appended with a rotary receiving pool was used to continuously produce shear-patterned hydrogel microfibers with aligned submicron topography. The process that the flow-induced shear force reshapes the surface of hydrogel fiber into aligned submicron topography was systematically analysed. Afterwards, the effect of fiber topography on cellular longitudinal spread and elongation was investigated by culturing rat neuron-like PC12 cells and human osteosarcoma MG63 cells with the spun hydrogel microfibers, respectively. The results suggested that the stronger shear flow force would lead to more distinct aligned submicron topography on fiber surface, which could induce cell orientation along with fiber axis and therefore form the cell-matrix dual-alignment. Finally, a multi-hierarchical tissue-like structure constructed by dual-oriented cell-matrix assemblies was fabricated based on this wet-spinning method. This work is believed to be a potentially novel biofabrication scheme for bottom-up constructing of engineered linear tissue, such as nerve bundle, cortical bone, muscle and hepatic cord. PMID:29026644

Periodic density functional theory study of spin crossover in the cesium iron hexacyanochromate prussian blue analog

NASA Astrophysics Data System (ADS)

Wojdeł, Jacek C.; Moreira, Ibério de P. R.; Illas, Francesc

2009-01-01

This paper presents a detailed theoretical analysis of the electronic structure of the CsFe[Cr(CN)6] prussian blue analog with emphasis on the structural origin of the experimentally observed spin crossover transition in this material. Periodic density functional calculations using generalized gradient approximation (GGA)+U and nonlocal hybrid exchange-correlation potentials show that, for the experimental low temperature crystal structure, the t2g6eg0 low spin configuration of FeII is the most stable and CrIII (S =3/2, t2g3eg0) remains the same in all cases. This is also found to be the case for the low spin GGA+U fully relaxed structure with the optimized unit cell. A completely different situation emerges when calculations are carried out using the experimental high temperature structure. Here, GGA+U and hybrid density functional theory calculations consistently predict that the t2g4eg2 FeII high spin configuration is the ground state. However, the two spin configurations appear to be nearly degenerate when calculations are carried out for the geometries arising from a GGA+U full relaxation of the atomic structure carried out at experimental high temperature lattice constant. A detailed analysis of the energy difference between the two spin configurations as a function of the lattice constant strongly suggests that the observed spin crossover transition has a structural origin with non-negligible entropic contributions of the high spin state.

Electric dipole moment of diatomic molecules by configuration interaction. V - Two states of /2/Sigma/+/ symmetry in CN.

NASA Technical Reports Server (NTRS)

Green, S.

1972-01-01

Previous accurate dipole moment calculation techniques are modified to be applicable to higher excited states of symmetry. The self-consistent fields and configuration interactions are calculated for the X(2)Sigma(+) and B(2)Sigma(+) states of CN. Spin hyperfine constants and spin density at the nucleus are considered in the context of one-electron operator properties. The values of the self-consistent field and configuration interaction for the spin density are compared with experimental values for several diatomic molecules.

Efficient spin-filter and negative differential resistance behaviors in FeN4 embedded graphene nanoribbon device

NASA Astrophysics Data System (ADS)

Liu, N.; Liu, J. B.; Yao, K. L.; Ni, Y.; Wang, S. L.

2016-03-01

In this paper, we propose a new device of spintronics by embedding two FeN4 molecules into armchair graphene nanoribbon and sandwiching them between N-doped graphene nanoribbon electrodes. Our first-principle quantum transport calculations show that the device is a perfect spin filter with high spin-polarizations both in parallel configuration (PC) and antiparallel configuration (APC). Moreover, negative differential resistance phenomena are obtained for the spin-down current in PC, and the spin-up and spin-down currents in APC. These transport properties are explained by the bias-dependent evolution of molecular orbitals and the transmission spectra.

Study for new hardmask process scheme

NASA Astrophysics Data System (ADS)

Lee, Daeyoup; Tatti, Phillip; Lee, Richard; Chang, Jack; Cho, Winston; Bae, Sanggil

2017-03-01

Hardmask processes are a key technique to enable low-k semiconductors, but they can have an impact on patterning control, influencing defectivity, alignment, and overlay. Specifically, amorphous carbon layer (ACL) hardmask schemes can negatively affect overlay by creating distorted alignment signals. A new scheme needs to be developed that can be inserted where amorphous carbon is used but provide better alignment performance. Typical spin-on carbon (SOC) materials used in other hardmask schemes have issues with DCD-FCD skew. In this paper we will evaluate new spin-on carbon material with a higher carbon content that could be a candidate to replace amorphous carbon.

Extra-large remnant recoil velocities and spins from near-extremal-Bowen-York-spin black-hole binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dain, Sergio; Max Planck Institute for Gravitational Physics; Lousto, Carlos O.

2008-07-15

We evolve equal-mass, equal-spin black-hole binaries with specific spins of a/m{sub H}{approx}0.925, the highest spins simulated thus far and nearly the largest possible for Bowen-York black holes, in a set of configurations with the spins counteraligned and pointing in the orbital plane, which maximizes the recoil velocities of the merger remnant, as well as a configuration where the two spins point in the same direction as the orbital angular momentum, which maximizes the orbital hangup effect and remnant spin. The coordinate radii of the individual apparent horizons in these cases are very small and the simulations require very high centralmore » resolutions (h{approx}M/320). We find that these highly spinning holes reach a maximum recoil velocity of {approx}3300 km s{sup -1} (the largest simulated so far) and, for the hangup configuration, a remnant spin of a/m{sub H}{approx}0.922. These results are consistent with our previous predictions for the maximum recoil velocity of {approx}4000 km s{sup -1} and remnant spin; the latter reinforcing the prediction that cosmic censorship is not violated by merging highly spinning black-hole binaries. We also numerically solve the initial data for, and evolve, a single maximal-Bowen-York-spin black hole, and confirm that the 3-metric has an O(r{sup -2}) singularity at the puncture, rather than the usual O(r{sup -4}) singularity seen for nonmaximal spins.« less

Study of J/ψ spin alignment in proton-proton collisions at s = 200 GeV in the PHENIX experiment at RHIC

NASA Astrophysics Data System (ADS)

Shoji, Kohei

2009-10-01

Non-relativisitic QCD calculations using Color Octet Models (COMs) succeed in describing the production cross section of heavy quarkonia measured by CDF and other experiments. However, these models can not reproduce the experimental data for J/ψ spin alignment (polarization). The understanding of the heavy quarkonium production mechanism cannot proceed without additional experimental measurements. The J/ψ spin alignment is experimentally determined by measuring the decay angular distribution of leptons in the J/ψ center of mass system. The anisotropy in the helicity frame was measured at CDF; however, the necessity of analyzing data with respect to another frame like Collins-Soper was recently discussed because the proper polarization axis which is sensitive to the interesting physics phenomenon is not known well. Moreover, measurements of not only the polar angular distribution but also the azimuthal one are important. Proton-proton collision experiments are in progress at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory. The PHENIX experiment at RHIC has muon spectrometers which can detect decay muons from J/ψ at forward and backward rapidity, 1.2<|η|<2.2. We present the status of our J/ψ spin alignment study in proton-proton collisions at s = 200 GeV.

Rockets for spin recovery

NASA Technical Reports Server (NTRS)

Whipple, R. D.

1980-01-01

The potential effectiveness of rockets as an auxiliary means for an aircraft to effect recovery from spins was investigated. The advances in rocket technology produced by the space effort suggested that currently available systems might obviate many of the problems encountered in earlier rocket systems. A modern fighter configuration known to exhibit a flat spin mode was selected. An analytical study was made of the thrust requirements for a rocket spin recovery system for the subject configuration. These results were then applied to a preliminary systems study of rocket components appropriate to the problem. Subsequent spin tunnel tests were run to evaluate the analytical results.

Anisotropic antiferromagnetic order in the spin-orbit coupled trigonal-lattice Ca2Sr2IrO6

NASA Astrophysics Data System (ADS)

Sheng, Jieming; Ye, Feng; Hoffmann, Christina; Cooper, Valentino R.; Okamoto, Satoshi; Terzic, Jasminka; Zheng, Hao; Zhao, Hengdi; Cao, G.

2018-06-01

We used single-crystal x-ray and neutron diffraction to investigate the crystal and magnetic structures of trigonal lattice iridate Ca2Sr2IrO6 . The crystal structure is determined to be R 3 ¯ with two distinct Ir sites. The system exhibits long-range antiferromagnetic order below TN=13.1 K. The magnetic wave vector is identified as (0,0.5,1) with ferromagnetic coupling along the a axis and antiferromagnetic correlation along the b axis. Spins align dominantly within the basal plane along the [1,2,0] direction and tilt 34∘ toward the c axis. The ordered moment is 0.66(3) μB/Ir, larger than other iridates where iridium ions form corner- or edge-sharing IrO6 octahedral networks. The tilting angle is reduced to ≈19∘ when a magnetic field of 4.9 T is applied along the c axis. Density functional theory calculations confirm that the experimentally determined magnetic configuration is the most probable ground state with an insulating gap ˜0.5 eV.

Control of electron spin and orbital resonances in quantum dots through spin-orbit interactions

NASA Astrophysics Data System (ADS)

Stano, Peter; Fabian, Jaroslav

2008-01-01

The influence of a resonant oscillating electromagnetic field on a single electron in coupled lateral quantum dots in the presence of phonon-induced relaxation and decoherence is investigated. Using symmetry arguments, it is shown that the spin and orbital resonances can be efficiently controlled by spin-orbit interactions. The control is possible due to the strong sensitivity of the Rabi frequency to the dot configuration (the orientation of the dot and the applied static magnetic field); the sensitivity is a result of the anisotropy of the spin-orbit interactions. The so-called easy passage configuration is shown to be particularly suitable for a magnetic manipulation of spin qubits, ensuring long spin relaxation times and protecting the spin qubits from electric field disturbances accompanying on-chip manipulations.

Ortho-para spin isomers of the protons in the methylene group--possible implications for protein structure.

PubMed

Shinitzky, Meir; Elitzur, Avshalom C

2006-09-01

The two hydrogen atoms attached to the carbon in the methylene group are of two different spin configurations, similar to those in the case of water: ortho, where the two proton spins are parallel to each other, and para, where they are antiparallel. The ortho configuration has three degenerate states, while the para configuration is singular, leading to a statistical ratio of these isomers 3:1 ortho/para. Such spin isomers are present in glycine and most chiral amino acids where they may induce broadening of structural zones, a possibility which remains to be assessed. The implications of this neglected possibility could be far-reaching, in particular with respect to protein structure and the origins of biochirality.

Implications of the Low Binary Black Hole Aligned Spins Observed by LIGO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hotokezaka, Kenta; Piran, Tsvi

We explore the implications of the low-spin components along the orbital axis observed in an Advanced LIGO O1 run on binary black hole (BBH) merger scenarios in which the merging BBHs have evolved from field binaries. The coalescence time determines the initial orbital separation of BBHs. This, in turn, determines whether the stars are synchronized before collapse, and hence determines their projected spins. Short coalescence times imply synchronization and large spins. Among known stellar objects, Wolf–Rayet (WR) stars seem to be the only progenitors consistent with the low aligned spins observed in LIGO’s O1, provided that the orbital axis maintainsmore » its direction during the collapse. We calculate the spin distribution of BBH mergers in the local universe, and its redshift evolution for WR progenitors. Assuming that the BBH formation rate peaks around a redshift of ∼2–3, we show that BBH mergers in the local universe are dominated by low-spin events. The high-spin population starts to dominate at a redshift of ∼0.5–1.5. WR stars are also progenitors of long gamma-ray bursts that take place at a comparable rate to BBH mergers. We discuss the possible connection between the two phenomena. Additionally, we show that hypothetical Population III star progenitors are also possible. Although WR and Population III progenitors are consistent with the current data, both models predict a non-vanishing fraction of high positive values of the BBHs’ aligned spin. If those are not detected within the coming LIGO/Virgo runs, it will be unlikely that the observed BBHs formed via field binaries.« less

Implementing a search for gravitational waves from binary black holes with nonprecessing spin

NASA Astrophysics Data System (ADS)

Capano, Collin; Harry, Ian; Privitera, Stephen; Buonanno, Alessandra

2016-06-01

Searching for gravitational waves (GWs) from binary black holes (BBHs) with LIGO and Virgo involves matched-filtering data against a set of representative signal waveforms—a template bank—chosen to cover the full signal space of interest with as few template waveforms as possible. Although the component black holes may have significant angular momenta (spin), previous searches for BBHs have filtered LIGO and Virgo data using only waveforms where both component spins are zero. This leads to a loss of signal-to-noise ratio for signals where this is not the case. Combining the best available template placement techniques and waveform models, we construct a template bank of GW signals from BBHs with component spins χ1 ,2∈[-0.99 ,0.99 ] aligned with the orbital angular momentum, component masses m1 ,2∈[2 ,48 ]M⊙ , and total mass Mtotal≤50 M⊙ . Using effective-one-body waveforms with spin effects, we show that less than 3% of the maximum signal-to-noise ratio (SNR) of these signals is lost due to the discreetness of the bank, using the early Advanced LIGO noise curve. We use simulated Advanced LIGO noise to compare the sensitivity of this bank to a nonspinning bank covering the same parameter space. In doing so, we consider the competing effects between improved SNR and signal-based vetoes and the increase in the rate of false alarms of the aligned-spin bank due to covering a larger parameter space. We find that the aligned-spin bank can be a factor of 1.3-5 more sensitive than a nonspinning bank to BBHs with dimensionless spins >+0.6 and component masses ≳20 M⊙ . Even larger gains are obtained for systems with equally high spins but smaller component masses.

Search for gravitational radiation from intermediate mass black hole binaries in data from the second LIGO-Virgo joint science run

NASA Astrophysics Data System (ADS)

Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Andersen, M.; Anderson, R.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauchrowitz, J.; Bauer, Th. S.; Bavigadda, V.; Behnke, B.; Bejger, M.; Beker, M. G.; Belczynski, C.; Bell, A. S.; Bell, C.; Bergmann, G.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bloemen, S.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bosi, L.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Buchman, S.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burman, R.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Celerier, C.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corpuz, A.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coughlin, S.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Canton, T. Dal; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; Debreczeni, G.; Degallaix, J.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Donath, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dossa, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Effler, A.; Eggenstein, H.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Feroz, F.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hooper, S.; Hopkins, P.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jaranowski, P.; Ji, Y.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karlen, J.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Keiser, G. M.; Keitel, D.; Kelley, D. B.; Kells, W.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, C.; Kim, K.; Kim, N. G.; Kim, N.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Leonardi, M.; Leong, J. R.; Le Roux, A.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B.; Lewis, J.; Li, T. G. F.; Libbrecht, K.; Libson, A.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M. J.; Lück, H.; Luijten, E.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macarthur, J.; Macdonald, E. P.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Maglione, C.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mangini, N.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; McLin, K.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meinders, M.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyers, P.; Miao, H.; Michel, C.; Mikhailov, E. E.; Milano, L.; Milde, S.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Moesta, P.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nanda Kumar, D.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nelemans, G.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palashov, O.; Palomba, C.; Pan, H.; Pan, Y.; Pankow, C.; Paoletti, F.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poteomkin, A.; Powell, J.; Prasad, J.; Premachandra, S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Qin, J.; Quetschke, V.; Quintero, E.; Quiroga, G.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Ramirez, K.; Rapagnani, P.; Raymond, V.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Reid, S.; Reitze, D. H.; Rhoades, E.; Ricci, F.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J. R.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Scheuer, J.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Singh, R.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Son, E. J.; Sorazu, B.; Souradeep, T.; Staley, A.; Stebbins, J.; Steinlechner, J.; Steinlechner, S.; Stephens, B. C.; Steplewski, S.; Stevenson, S.; Stone, R.; Stops, D.; Strain, K. A.; Straniero, N.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Urbanek, K.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S. S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Wang, M.; Wang, X.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Williams, K.; Williams, L.; Williams, R.; Williams, T.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yang, Z.; Yoshida, S.; Yvert, M.; ZadroŻny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, Fan; Zhang, L.; Zhao, C.; Zhu, X. J.; Zucker, M. E.; Zuraw, S.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2014-06-01

This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009-October 2010) and was sensitive to IMBHBs with a range up to ˜200 Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450 M⊙ and mass ratios between 0.25 and 1 were placed by combining this analysis with an analogous search performed on data from the first LIGO-Virgo joint science run (November 2005-October 2007). The most stringent limit was set for systems consisting of two 88 M⊙ black holes and is equal to 0.12 Mpc-3 Myr-1 at the 90% confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with nonspinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with antialigned spins decreases the visible volume by ˜20%.

Strontium ruthenate-anatase titanium dioxide heterojunctions from first-principles: Electronic structure, spin, and interface dipoles

NASA Astrophysics Data System (ADS)

Ferdous, Naheed; Ertekin, Elif

2016-07-01

The epitaxial integration of functional oxides with wide band gap semiconductors offers the possibility of new material systems for electronics and energy conversion applications. We use first principles to consider an epitaxial interface between the correlated metal oxide SrRuO3 and the wide band gap semiconductor TiO2, and assess energy level alignment, interfacial chemistry, and interfacial dipole formation. Due to the ferromagnetic, half-metallic character of SrRuO3, according to which only one spin is present at the Fermi level, we demonstrate the existence of a spin dependent band alignment across the interface. For two different terminations of SrRuO3, the interface is found to be rectifying with a Schottky barrier of ≈1.3-1.6 eV, in good agreement with experiment. In the minority spin, SrRuO3 exhibits a Schottky barrier alignment with TiO2 and our calculated Schottky barrier height is in excellent agreement with previous experimental measurements. For majority spin carriers, we find that SrRuO3 recovers its exchange splitting gap and bulk-like properties within a few monolayers of the interface. These results demonstrate a possible approach to achieve spin-dependent transport across a heteroepitaxial interface between a functional oxide material and a conventional wide band gap semiconductor.

THE BANANA PROJECT. III. SPIN-ORBIT ALIGNMENT IN THE LONG-PERIOD ECLIPSING BINARY NY CEPHEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Carter, Joshua A.

Binaries are not always neatly aligned. Previous observations of the DI Her system showed that the spin axes of both stars are highly inclined with respect to one another and the orbital axis. Here, we report on a measurement of the spin-axis orientation of the primary star of the NY Cep system, which is similar to DI Her in many respects: it features two young early-type stars ({approx}6 Myr, B0.5V+B2V), in an eccentric and relatively long-period orbit (e = 0.48, P = 15fd3). The sky projections of the rotation vector and the spin vector are well aligned ({beta}{sub p} =more » 2{sup 0} {+-} 4{sup 0}), in strong contrast to DI Her. Although no convincing explanation has yet been given for the misalignment of DI Her, our results show that the phenomenon is not universal, and that a successful theory will need to account for the different outcome in the case of NY Cep.« less

Disparate ultrafast dynamics of itinerant and localized magnetic moments in gadolinium metal

PubMed Central

Frietsch, B.; Bowlan, J.; Carley, R.; Teichmann, M.; Wienholdt, S.; Hinzke, D.; Nowak, U.; Carva, K.; Oppeneer, P. M.; Weinelt, M.

2015-01-01

The Heisenberg–Dirac intra-atomic exchange coupling is responsible for the formation of the atomic spin moment and thus the strongest interaction in magnetism. Therefore, it is generally assumed that intra-atomic exchange leads to a quasi-instantaneous aligning process in the magnetic moment dynamics of spins in separate, on-site atomic orbitals. Following ultrashort optical excitation of gadolinium metal, we concurrently record in photoemission the 4f magnetic linear dichroism and 5d exchange splitting. Their dynamics differ by one order of magnitude, with decay constants of 14 versus 0.8 ps, respectively. Spin dynamics simulations based on an orbital-resolved Heisenberg Hamiltonian combined with first-principles calculations explain the particular dynamics of 5d and 4f spin moments well, and corroborate that the 5d exchange splitting traces closely the 5d spin-moment dynamics. Thus gadolinium shows disparate dynamics of the localized 4f and the itinerant 5d spin moments, demonstrating a breakdown of their intra-atomic exchange alignment on a picosecond timescale. PMID:26355196

Electrode alignment of transverse tripoles using a percutaneous triple-lead approach in spinal cord stimulation

NASA Astrophysics Data System (ADS)

Sankarasubramanian, V.; Buitenweg, J. R.; Holsheimer, J.; Veltink, P.

2011-02-01

The aim of this modeling study is to determine the influence of electrode alignment of transverse tripoles on the paresthesia coverage of the pain area in spinal cord stimulation, using a percutaneous triple-lead approach. Transverse tripoles, comprising a central cathode and two lateral anodes, were modeled on the low-thoracic vertebral region (T10-T12) using percutaneous triple-lead configurations, with the center lead on the spinal cord midline. The triple leads were oriented both aligned and staggered. In the staggered configuration, the anodes were offset either caudally (caudally staggered) or rostrally (rostrally staggered) with respect to the midline cathode. The transverse tripolar field steering with the aligned and staggered configurations enabled the estimation of dorsal column fiber thresholds (IDC) and dorsal root fiber thresholds (IDR) at various anodal current ratios. IDC and IDR were considerably higher for the aligned transverse tripoles as compared to the staggered transverse tripoles. The aligned transverse tripoles facilitated deeper penetration into the medial dorsal columns (DCs). The staggered transverse tripoles always enabled broad and bilateral DC activation, at the expense of mediolateral steerability. The largest DC recruited area was obtained with the rostrally staggered transverse tripole. Transverse tripolar geometries, using percutaneous leads, allow for selective targeting of either medial or lateral DC fibers, if and only if the transverse tripole is aligned. Steering of anodal currents between the lateral leads of the staggered transverse tripoles cannot target medially confined populations of DC fibers in the spinal cord. An aligned transverse tripolar configuration is strongly recommended, because of its ability to provide more post-operative flexibility than other configurations.

A Two-Dimensional Manganese Gallium Nitride Surface Structure Showing Ferromagnetism at Room Temperature.

PubMed

Ma, Yingqiao; Chinchore, Abhijit V; Smith, Arthur R; Barral, María Andrea; Ferrari, Valeria

2018-01-10

Practical applications of semiconductor spintronic devices necessitate ferromagnetic behavior at or above room temperature. In this paper, we demonstrate a two-dimensional manganese gallium nitride surface structure (MnGaN-2D) which is atomically thin and shows ferromagnetic domain structure at room temperature as measured by spin-resolved scanning tunneling microscopy and spectroscopy. Application of small magnetic fields proves that the observed magnetic domains follow a hysteretic behavior. Two initially oppositely oriented MnGaN-2D domains are rotated into alignment with only 120 mT and remain mostly in alignment at remanence. The measurements are further supported by first-principles theoretical calculations which reveal highly spin-polarized and spin-split surface states with spin polarization of up to 95% for manganese local density of states.

Nutation control during precession of a spin-stabilized spacecraft

NASA Technical Reports Server (NTRS)

1974-01-01

Precession maneuver control laws for single-spin spacecraft are investigated so that nutation is concurrently controlled. Analysis has led to the development of two types of control laws employing precession modulation for concurrent nutation control. Results were verified through digital simulation of a Synchronous Meteorological Satellite (SMS) configuration. An addition research effort was undertaken to investigate the cause and elimination of nutation anomalies in dual-spin spacecraft. A literature search was conducted and a dual-spin configuration was simulated to verify that nutational anomalies are not predicted by the existing nonlinear model. No conclusions were drawn as to the cause of the observed nutational anomalies in dual-spin spacecraft.

Spin-dependent thermoelectric effect and spin battery mechanism in triple quantum dots with Rashba spin-orbital interaction

NASA Astrophysics Data System (ADS)

Xu, Wei-Ping; Zhang, Yu-Ying; Wang, Qiang; Nie, Yi-Hang

2016-11-01

We have studied spin-dependent thermoelectric transport through parallel triple quantum dots with Rashba spin-orbital interaction (RSOI) embedded in an Aharonov-Bohm interferometer connected symmetrically to leads using nonequilibrium Green’s function method in the linear response regime. Under the appropriate configuration of magnetic flux phase and RSOI phase, the spin figure of merit can be enhanced and is even larger than the charge figure of merit. In particular, the charge and spin thermopowers as functions of both the magnetic flux phase and the RSOI phase present quadruple-peak structures in the contour graphs. For some specific configuration of the two phases, the device can provide a mechanism that converts heat into a spin voltage when the charge thermopower vanishes while the spin thermopower is not zero, which is useful in realizing the thermal spin battery and inducing a pure spin current in the device. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274208 and 11447170).

Correlation study of theoretical and experimental results for spin tests of a 1/10 scale radio control model

NASA Technical Reports Server (NTRS)

Bihrle, W., Jr.

1976-01-01

A correlation study was conducted to determine the ability of current analytical spin prediction techniques to predict the flight motions of a current fighter airplane configuration during the spin entry, the developed spin, and the spin recovery motions. The airplane math model used aerodynamics measured on an exact replica of the flight test model using conventional static and forced-oscillation wind-tunnel test techniques and a recently developed rotation-balance test apparatus capable of measuring aerodynamics under steady spinning conditions. An attempt was made to predict the flight motions measured during stall/spin flight testing of an unpowered, radio-controlled model designed to be a 1/10 scale, dynamically-scaled model of a current fighter configuration. Comparison of the predicted and measured flight motions show that while the post-stall and spin entry motions were not well-predicted, the developed spinning motion (a steady flat spin) and the initial phases of the spin recovery motion are reasonably well predicted.

Non-linear tides in a homogeneous rotating planet or star: global modes and elliptical instability

NASA Astrophysics Data System (ADS)

Barker, Adrian J.; Braviner, Harry J.; Ogilvie, Gordon I.

2016-06-01

We revisit the global modes and instabilities of homogeneous rotating ellipsoidal fluid masses, which are the simplest global models of rotationally and tidally deformed gaseous planets or stars. The tidal flow in a short-period planet may be unstable to the elliptical instability, a hydrodynamic instability that can drive tidal evolution. We perform a global (and local WKB) analysis to study this instability using the elegant formalism of Lebovitz & Lifschitz. We survey the parameter space of global instabilities with harmonic orders ℓ ≤ 5, for planets with spins that are purely aligned (prograde) or anti-aligned (retrograde) with their orbits. In general, the instability has a much larger growth rate if the planetary spin and orbit are anti-aligned rather than aligned. We have identified a violent instability for anti-aligned spins outside of the usual frequency range for the elliptical instability (when n/Ω ≲ -1, where n and Ω are the orbital and spin angular frequencies, respectively) if the tidal amplitude is sufficiently large. We also explore the instability in a rigid ellipsoidal container, which is found to be quantitatively similar to that with a realistic free surface. Finally, we study the effect of rotation and tidal deformation on mode frequencies. We find that larger rotation rates and larger tidal deformations both decrease the frequencies of the prograde sectoral surface gravity modes. This increases the prospect of their tidal excitation, potentially enhancing the tidal response over expectations from linear theory. In a companion paper, we use our results to interpret global simulations of the elliptical instability.

Alignments of Dark Matter Halos with Large-scale Tidal Fields: Mass and Redshift Dependence

NASA Astrophysics Data System (ADS)

Chen, Sijie; Wang, Huiyuan; Mo, H. J.; Shi, Jingjing

2016-07-01

Large-scale tidal fields estimated directly from the distribution of dark matter halos are used to investigate how halo shapes and spin vectors are aligned with the cosmic web. The major, intermediate, and minor axes of halos are aligned with the corresponding tidal axes, and halo spin axes tend to be parallel with the intermediate axes and perpendicular to the major axes of the tidal field. The strengths of these alignments generally increase with halo mass and redshift, but the dependence is only on the peak height, ν \\equiv {δ }{{c}}/σ ({M}{{h}},z). The scaling relations of the alignment strengths with the value of ν indicate that the alignment strengths remain roughly constant when the structures within which the halos reside are still in a quasi-linear regime, but decreases as nonlinear evolution becomes more important. We also calculate the alignments in projection so that our results can be compared directly with observations. Finally, we investigate the alignments of tidal tensors on large scales, and use the results to understand alignments of halo pairs separated at various distances. Our results suggest that the coherent structure of the tidal field is the underlying reason for the alignments of halos and galaxies seen in numerical simulations and in observations.

Hysteresis-free spin valves with a noncollinear configuration of magnetic anisotropy

NASA Astrophysics Data System (ADS)

Naumova, L. I.; Milyaev, M. A.; Chernyshova, T. A.; Proglyado, V. V.; Kamenskii, I. Yu.; Ustinov, V. V.

2014-06-01

A noncollinear configuration of magnetic anisotropy in spin valves with strong and weak interlayer couplings has been formed by annealing and cooling in a magnetic field. The dependence of the low-field magnetoresistance hysteresis loop width on the angle between the applied magnetic field and the principal axes of the magnetic anisotropy in a spin valve has been investigated. It has been found that, only in the case of a strong ferromagnetic interlayer coupling, the formation of a noncollinear configuration of the magnetic anisotropy provides a hysteresis-free character of the magnetization reversal of the free layer with retaining the maximum magnetoresistance and magnetoresistive sensitivity.

Programmable superpositions of Ising configurations

NASA Astrophysics Data System (ADS)

Sieberer, Lukas M.; Lechner, Wolfgang

2018-05-01

We present a framework to prepare superpositions of bit strings, i.e., many-body spin configurations, with deterministic programmable probabilities. The spin configurations are encoded in the degenerate ground states of the lattice-gauge representation of an all-to-all connected Ising spin glass. The ground-state manifold is invariant under variations of the gauge degrees of freedom, which take the form of four-body parity constraints. Our framework makes use of these degrees of freedom by individually tuning them to dynamically prepare programmable superpositions. The dynamics combines an adiabatic protocol with controlled diabatic transitions. We derive an effective model that allows one to determine the control parameters efficiently even for large system sizes.

Puncture initial data for black-hole binaries with high spins and high boosts

NASA Astrophysics Data System (ADS)

Ruchlin, Ian; Healy, James; Lousto, Carlos O.; Zlochower, Yosef

2017-01-01

We solve the Hamiltonian and momentum constraints of general relativity for two black holes with nearly extremal spins and relativistic boosts in the puncture formalism. We use a non-conformally-flat ansatz with an attenuated superposition of two Lorentz-boosted, conformally Kerr or conformally Schwarzschild 3-metrics and their corresponding extrinsic curvatures. We compare evolutions of these data with the standard Bowen-York conformally flat ansatz (technically limited to intrinsic spins χ =S /MADM2=0.928 and boosts P /MADM=0.897 ), finding, typically, an order of magnitude smaller burst of spurious radiation and agreement with inspiral and merger. As a first case study, we evolve two equal-mass black holes from rest with an initial separation of d =12 M and spins χi=Si/mi2=0.99 , compute the waveforms produced by the collision, the energy and angular momentum radiated, and the recoil of the final remnant black hole. We find that the black-hole trajectories curve at close separations, leading to the radiation of angular momentum. We also study orbiting nonspinning and moderate-spin black-hole binaries and compare these with standard Bowen-York data. We find a substantial reduction in the nonphysical initial burst of radiation which leads to cleaner waveforms. Finally, we study the case of orbiting binary black-hole systems with spin magnitude χi=0.95 in an aligned configuration and compare waveform and final remnant results with those of the SXS Collaboration [54 A. H. Mroue et al., Phys. Rev. Lett. 111, 241104 (2013)., 10.1103/PhysRevLett.111.241104], finding excellent agreement. This represents the first moving puncture evolution of orbiting and spinning black holes exceeding the Bowen-York limit. Finally, we study different choices of the initial lapse and lapse evolution equation in the moving puncture approach to improve the accuracy and efficiency of the simulations.

The Spin and Orientation of Dark Matter Halos Within Cosmic Filaments

NASA Astrophysics Data System (ADS)

Zhang, Youcai; Yang, Xiaohu; Faltenbacher, Andreas; Springel, Volker; Lin, Weipeng; Wang, Huiyuan

2009-11-01

Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses lsim1013 h -1 M sun are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at small separation. Overall, the two algorithms for filament/sheet identification investigated here agree well with each other. The method based on halos alone can be easily adapted for use with observational data sets.

Configuration memory in patchwork dynamics for low-dimensional spin glasses

NASA Astrophysics Data System (ADS)

Yang, Jie; Middleton, A. Alan

2017-12-01

A patchwork method is used to study the dynamics of loss and recovery of an initial configuration in spin glass models in dimensions d =1 and d =2 . The patchwork heuristic is used to accelerate the dynamics to investigate how models might reproduce the remarkable memory effects seen in experiment. Starting from a ground-state configuration computed for one choice of nearest-neighbor spin couplings, the sample is aged up to a given scale under new random couplings, leading to the partial erasure of the original ground state. The couplings are then restored to the original choice and patchwork coarsening is again applied, in order to assess the recovery of the original state. Eventual recovery of the original ground state upon coarsening is seen in two-dimensional Ising spin glasses and one-dimensional clock models, while one-dimensional Ising spin systems neither lose nor gain overlap with the ground state during the recovery stage. The recovery for the two-dimensional Ising spin glasses suggests scaling relations that lead to a recovery length scale that grows as a power of the aging length scale.

Dynamics and stability of spinning flexible space tether systems

NASA Astrophysics Data System (ADS)

Tyc, George

This dissertation focuses on a detailed dynamical investigation of a previously unexplored tether configuration that involves a spinning two-body tethered system with flexible appendages on each end-body where the spin axis is nominally aligned along the tether. The original motivation for this work came after the flight of the first Canadian sub-orbital tether mission OEDIPUS-A in 1989 which employed this spinning tethered configuration. To everyone's surprise, one of the end-bodies was observed to exhibit a rapid divergence of its nutation angle. It was clear after this flight that there were some fundamental mechanisms associated with the interaction between the tether and the end-body that were not fully understood at that time. Hence, a Tether Dynamics Experiment (TDE) was formed and became a formal part of the scientific agenda for the follow-on mission OEDIPUS-C which flew in 1995. This dissertation describes the work that was conducted as part of the TDE and involves: theoretical investigations into the dynamics of this spinning tethered flexible body system; ground testing to validate the models and establish the tether properties; application of the models to develop a stabilization approach for OEDIPUS-C, and comparisons between theory and flight data from both OEDIPUS-A and OEDIPUS-C. Nonlinear equations of motion are developed for a spinning tethered system where the tether could be either spinning with the end-bodies or attached to small de-spun platforms on the end-bodies. Since the tether used for the OEDIPUS missions is not a string, as is often assumed, but rather a wire that has some bending stiffness, albeit small, the tether bending was also taken into account in the formulation. Two sets of ground tests are described that were used to validate the stability conditions and gain confidence in the mathematical models. One set involved hanging a body by a tether and spinning at different speeds to investigate the end-body stability. The other set used a tethered spinning end-body suspended on a set of gimbals and had a means to measure the end-body attitude in real-time. The mathematical models were then applied to investigate suitable stabilization approaches for OEDIPUS-C. In general, very good agreement was found between the theory and both the ground experiments and flight data. One of the surprising results from this work is the significance of the tether root bending effects. It is shown that it is this subtle effect that caused the rapid divergence in one of the end-bodies in the OEDIPUS-A mission which was unstable. For OEDIPUS-C, the situation was rectified by adding the booms to ensure "short term" stability and also by not spinning as rapidly. The OEDIPUS-C was very successful as all systems worked as planned and hence a superb set of flight dynamics data was collected. (Abstract shortened by UMI.)

Deep Neural Network Detects Quantum Phase Transition

NASA Astrophysics Data System (ADS)

Arai, Shunta; Ohzeki, Masayuki; Tanaka, Kazuyuki

2018-03-01

We detect the quantum phase transition of a quantum many-body system by mapping the observed results of the quantum state onto a neural network. In the present study, we utilized the simplest case of a quantum many-body system, namely a one-dimensional chain of Ising spins with the transverse Ising model. We prepared several spin configurations, which were obtained using repeated observations of the model for a particular strength of the transverse field, as input data for the neural network. Although the proposed method can be employed using experimental observations of quantum many-body systems, we tested our technique with spin configurations generated by a quantum Monte Carlo simulation without initial relaxation. The neural network successfully identified the strength of transverse field only from the spin configurations, leading to consistent estimations of the critical point of our model Γc = J.

Phase diagram of the Shastry-Sutherland Kondo lattice model with classical localized spins: a variational calculation study

NASA Astrophysics Data System (ADS)

Shahzad, Munir; Sengupta, Pinaki

2017-08-01

We study the Shastry-Sutherland Kondo lattice model with additional Dzyaloshinskii-Moriya (DM) interactions, exploring the possible magnetic phases in its multi-dimensional parameter space. Treating the local moments as classical spins and using a variational ansatz, we identify the parameter ranges over which various common magnetic orderings are potentially stabilized. Our results reveal that the competing interactions result in a heightened susceptibility towards a wide range of spin configurations including longitudinal ferromagnetic and antiferromagnetic order, coplanar flux configurations and most interestingly, multiple non-coplanar configurations including a novel canted-flux state as the different Hamiltonian parameters like electron density, interaction strengths and degree of frustration are varied. The non-coplanar and non-collinear magnetic ordering of localized spins behave like emergent electromagnetic fields and drive unusual transport and electronic phenomena.

An LDA+U study of the photoemission spectra of ground state phase of americium and curium

NASA Astrophysics Data System (ADS)

Islam, Md; Ray, Asok

2009-03-01

We have investigated the photoemission spectra and other ground state properties such as equilibrium volume and bulk modulus of dhcp americium and the density of states and magnetic properties of dhcp curium using LDA+U method. Our calculations show that spin polarized americium is energetically favorable but spin degenerate configuration produces experimental quantities much better than that calculated using spin polarized configuration. The DOS calculated using LDA+U with both non-magnetic and spin polarized configurations is compared and the non-magnetic DOS is shown to be in good agreement with experimental photoemission spectra when U=4.5 eV. In spin polarized case, U is observed to increase the splitting between occupied and unoccupied bands by enhancing Stoner parameter. The results are shown to be in good agreement with that calculated using dynamical mean field theory for these two heavy actinides. For curium, exchange interaction appears to play the dominant role in its magnetic stability.

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-02-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 10 half-nights with Keck/HIRES spread over 2010A and 2010B, to measure spin-orbit angles for 9 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-08-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 4 half-nights with Keck/HIRES spread over the 2010B semester, to measure spin-orbit angles for 4 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

Fabrication process for polymer PLC platforms with V-grooves for passive alignment

NASA Astrophysics Data System (ADS)

Park, Suntak; Lee, Jong-Moo; Ahn, Joon Tae; Baek, Yong-Soon

2005-12-01

A method for polymer planar lightwave circuit (PLC) devices fabricated on a substrate with V-grooves is developed for passive alignment of an optical fiber to a polymer waveguide. In order to minimize thickness nonuniformity of polymer layers caused by the V-grooves, dry film resist (DFR) is used. The V-grooves are covered with the DFR before the polymer layers are spin-coated on the substrate. The DFR prevents the polymer from being filled in the V-grooves as well as from being spin-coated nonuniformly on the substrate. This process provides a simple and cost-effective fabrication method of polymer PLCs or platforms for passive alignment.

An Investigation of the Free-Spinning and Recovery Characteristics of a 1/24-Scale Model of the Grumman F11F-1 Airplane with Alternate Nose Configurations with and without Wing Fuel Tanks, TED No. NACA AD 395

NASA Technical Reports Server (NTRS)

Bowman, James S., Jr.

1958-01-01

A supplementary investigation has been conducted in the langley 20-foot free-spinning tunnel on a l/24-scale model of the Grumman F11F-1 airplane to determine the spin and recovery characteristics with alternate nose configurations, the production version and the elongated APS-67 version, with and without empty and full wing tanks. When spins were obtained with either alternate nose configuration, they were oscillatory and recovery characteristics were considered unsatisfactory on the basis of the fact that very slow recoveries were indicated to be possible. The simultaneous extension of canards near the nose of the model with rudder reversal was effective in rapidly terminating the spin. The addition of empty wing tanks had little effect on the developed spin and recovery characteristics. The model did not spin erect with full wing tanks. For optimum recovery from inverted spins, the rudder should be reversed to 22O against the spin and simultaneously the flaperons should be moved with the developed spin; the stick should be held at or moved to full forward longitudinally. The minimum size parachute required to insure satisfactory recoveries in an emergency was found to be 12 feet in diameter (laid out flat) with a drag coefficient of 0.64 (based on the laid-out-flat diameter) and a towline length of 32 feet.

Free-Spinning-Tunnel Tests of a 1/24-Scale Model of the Grumman XF9F-2 Airplane, TED No. NACA DE 317

NASA Technical Reports Server (NTRS)

Berman, Theodore

1948-01-01

An investigation of the spin and recovery characteristics of a scale model of the Grumman XF9F-2 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect and inverted spin and recovery characteristics of the model in the flight loading were determined. The investigation also included spin-recovery-parachute, pilot-escape, and rudder-pedal- . force tests. The recovery characteristics of the model were satisfactory for all configurations tested. Spins for the normal control configuration were oscillatory in roll and yaw. Deflecting the leading-edge flaps or the dive brakes did not change the spin and recovery characteristics of the model noticeably. A 10.0-foot tail parachute or a 6.0-foot wing-tip parachute (drag coefficient of 0.75) was found to be effective for recoveries from demonstration spins. The rudder forces in the spin appeared to be within the capabilities of the pilot.

Density matrix-based time-dependent configuration interaction approach to ultrafast spin-flip dynamics

NASA Astrophysics Data System (ADS)

Wang, Huihui; Bokarev, Sergey I.; Aziz, Saadullah G.; Kühn, Oliver

2017-08-01

Recent developments in attosecond spectroscopy yield access to the correlated motion of electrons on their intrinsic timescales. Spin-flip dynamics is usually considered in the context of valence electronic states, where spin-orbit coupling is weak and processes related to the electron spin are usually driven by nuclear motion. However, for core-excited states, where the core-hole has a nonzero angular momentum, spin-orbit coupling is strong enough to drive spin-flips on a much shorter timescale. Using density matrix-based time-dependent restricted active space configuration interaction including spin-orbit coupling, we address an unprecedentedly short spin-crossover for the example of L-edge (2p→3d) excited states of a prototypical Fe(II) complex. This process occurs on a timescale, which is faster than that of Auger decay (∼4 fs) treated here explicitly. Modest variations of carrier frequency and pulse duration can lead to substantial changes in the spin-state yield, suggesting its control by soft X-ray light.

Thermal spin filtering effect and giant magnetoresistance of half-metallic graphene nanoribbon co-doped with non-metallic Nitrogen and Boron

NASA Astrophysics Data System (ADS)

Huang, Hai; Zheng, Anmin; Gao, Guoying; Yao, Kailun

2018-03-01

Ab initio calculations based on density functional theory and non-equilibrium Green's function are performed to investigate the thermal spin transport properties of single-hydrogen-saturated zigzag graphene nanoribbon co-doped with non-metallic Nitrogen and Boron in parallel and anti-parallel spin configurations. The results show that the doped graphene nanoribbon is a full half-metal. The two-probe system based on the doped graphene nanoribbon exhibits various excellent spin transport properties, including the spin-filtering effect, the spin Seebeck effect, the single-spin negative differential thermal resistance effect and the sign-reversible giant magnetoresistance feature. Excellently, the spin-filtering efficiency can reach nearly 100% in the parallel configuration and the magnetoresistance ratio can be up to -1.5 × 1010% by modulating the electrode temperature and temperature gradient. Our findings indicate that the metal-free doped graphene nanoribbon would be a promising candidate for spin caloritronic applications.

Tetraquark mixing framework for isoscalar resonances in light mesons

NASA Astrophysics Data System (ADS)

Kim, Hungchong; Kim, K. S.; Cheoun, Myung-Ki; Oka, Makoto

2018-05-01

Recently, a tetraquark mixing framework has been proposed for light mesons and applied more or less successfully to the isovector resonances, a0(980 ) , a0(1450 ) , as well as to the isodoublet resonances, K0*(800 ),K0*(1430 ). In this work, we present a more extensive view on the mixing framework and apply this framework to the isoscalar resonances, f0(500 ), f0(980 ), f0(1370 ), f0(1500 ). Tetraquarks in this framework can have two spin configurations containing either spin-0 diquark or spin-1 diquark and each configuration forms a nonet in flavor space. The two spin configurations are found to mix strongly through the color-spin interactions. Their mixtures, which diagonalize the hyperfine masses, can generate the physical resonances constituting two nonets, which, in fact, coincide roughly with the experimental observation. We identify that f0(500 ), f0(980 ) are the isoscalar members in the light nonet, and f0(1370 ), f0(1500 ) are the similar members in the heavy nonet. This means that the spin configuration mixing, as it relates the corresponding members in the two nonets, can generate f0(500 ) , f0(1370 ) among the members in light mass, and f0(980 ) , f0(1500 ) in heavy mass. The complication arises because the isoscalar members of each nonet are subject to an additional flavor mixing known as Okubo-Zweig-Iizuka rule so that f0(500 ) , f0(980 ) , and similarly f0(1370 ) , f0(1500 ) , are the mixture of two isoscalar members belonging to an octet and a singlet in SUf(3 ) . The tetraquark mixing framework including the flavor mixing is tested for the isoscalar resonances in terms of the mass splitting and the fall-apart decay modes. The mass splitting among the isoscalar resonances is found to be consistent qualitatively with their hyperfine mass splitting strongly driven by the spin configuration mixing, which suggests that the tetraquark mixing framework works. The fall-apart modes from our tetraquarks also seem to be consistent with the experimental modes. We also discuss possible existence of the spin-1 tetraquarks that can be constructed by the spin-1 diquark.

Band structure and spin texture of Bi2Se3 3 d ferromagnetic metal interface

NASA Astrophysics Data System (ADS)

Zhang, Jia; Velev, Julian P.; Dang, Xiaoqian; Tsymbal, Evgeny Y.

2016-07-01

The spin-helical surface states in a three-dimensional topological insulator (TI), such as Bi2Se3 , are predicted to have superior efficiency in converting charge current into spin polarization. This property is said to be responsible for the giant spin-orbit torques observed in ferromagnetic metal/TI structures. In this work, using first-principles and model tight-binding calculations, we investigate the interface between the topological insulator Bi2Se3 and 3 d -transition ferromagnetic metals Ni and Co. We find that the difference in the work functions of the topological insulator and the ferromagnetic metals shift the topological surface states down about 0.5 eV below the Fermi energy where the hybridization of these surface states with the metal bands destroys their helical spin structure. The band alignment of Bi2Se3 and Ni (Co) places the Fermi energy far in the conduction band of bulk Bi2Se3 , where the spin of the carriers is aligned with the magnetization in the metal. Our results indicate that the topological surface states are unlikely to be responsible for the huge spin-orbit torque effect observed experimentally in these systems.

Direct observation of the alignment of ferromagnetic spins by antiferromagnetic spins

NASA Astrophysics Data System (ADS)

Nolting, F.; Scholl, A.; Stöhr, J.; Seo, J. W.; Fompeyrine, J.; Siegwart, H.; Locquet, J.-P.; Anders, S.; Lüning, J.; Fullerton, E. E.; Toney, M. F.; Scheinfein, M. R.; Padmore, H. A.

2000-06-01

The arrangement of spins at interfaces in a layered magnetic material often has an important effect on the properties of the material. One example of this is the directional coupling between the spins in an antiferromagnet and those in an adjacent ferromagnet, an effect first discovered in 1956 and referred to as exchange bias. Because of its technological importance for the development of advanced devices such as magnetic read heads and magnetic memory cells, this phenomenon has received much attention. Despite extensive studies, however, exchange bias is still poorly understood, largely due to the lack of techniques capable of providing detailed information about the arrangement of magnetic moments near interfaces. Here we present polarization-dependent X-ray magnetic dichroism spectro-microscopy that reveals the micromagnetic structure on both sides of a ferromagnetic-antiferromagnetic interface. Images of thin ferromagnetic Co films grown on antiferromagnetic LaFeO3 show a direct link between the arrangement of spins in each material. Remanent hysteresis loops, recorded for individual ferromagnetic domains, show a local exchange bias. Our results imply that the alignment of the ferromagnetic spins is determined, domain by domain, by the spin directions in the underlying antiferromagnetic layer.

Collective and non-collective structures in nuclei of mass region A ≈ 125

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, A. K.; Collaboration: INGA Collaboration; Gammasphere Collaboration

Generation of angular momentum in nuclei is a key question in nuclear structure studies. In single particle model, it is due to alignment of spin of individual nucleon available in the valence space, whereas coherent motion of nucleons are assumed in the collective model. The nuclei near the closed shell at Z = 50 with mass number A ≈ 120-125 represent ideal cases to explore the interplay between these competing mechanisms and the transition from non-collective to collective behavior or vice versa. Recent spectroscopic studies of nuclei in this region reveal several non-collective maximally aligned states representing the first kindmore » of excitation mechanism, where 8-12 particles above the {sup 114}Sn align their spins to generate these states. Deformed rotational bands feeding the non-collective states in the spin range I=20-25 and excitation energies around 10 MeV have also been observed. Structure of the collective and non-collective states are discussed in the framework of Cranked-Nilsson-Strutinsky model.« less

High performance current and spin diode of atomic carbon chain between transversely symmetric ribbon electrodes.

PubMed

Dong, Yao-Jun; Wang, Xue-Feng; Yang, Shuo-Wang; Wu, Xue-Mei

2014-08-21

We demonstrate that giant current and high spin rectification ratios can be achieved in atomic carbon chain devices connected between two symmetric ferromagnetic zigzag-graphene-nanoribbon electrodes. The spin dependent transport simulation is carried out by density functional theory combined with the non-equilibrium Green's function method. It is found that the transverse symmetries of the electronic wave functions in the nanoribbons and the carbon chain are critical to the spin transport modes. In the parallel magnetization configuration of two electrodes, pure spin current is observed in both linear and nonlinear regions. However, in the antiparallel configuration, the spin-up (down) current is prohibited under the positive (negative) voltage bias, which results in a spin rectification ratio of order 10(4). When edge carbon atoms are substituted with boron atoms to suppress the edge magnetization in one of the electrodes, we obtain a diode with current rectification ratio over 10(6).

High performance current and spin diode of atomic carbon chain between transversely symmetric ribbon electrodes

PubMed Central

Dong, Yao-Jun; Wang, Xue-Feng; Yang, Shuo-Wang; Wu, Xue-Mei

2014-01-01

We demonstrate that giant current and high spin rectification ratios can be achieved in atomic carbon chain devices connected between two symmetric ferromagnetic zigzag-graphene-nanoribbon electrodes. The spin dependent transport simulation is carried out by density functional theory combined with the non-equilibrium Green's function method. It is found that the transverse symmetries of the electronic wave functions in the nanoribbons and the carbon chain are critical to the spin transport modes. In the parallel magnetization configuration of two electrodes, pure spin current is observed in both linear and nonlinear regions. However, in the antiparallel configuration, the spin-up (down) current is prohibited under the positive (negative) voltage bias, which results in a spin rectification ratio of order 104. When edge carbon atoms are substituted with boron atoms to suppress the edge magnetization in one of the electrodes, we obtain a diode with current rectification ratio over 106. PMID:25142376

Spin-adapted open-shell random phase approximation and time-dependent density functional theory. I. Theory.

PubMed

Li, Zhendong; Liu, Wenjian

2010-08-14

The spin-adaptation of single-reference quantum chemical methods for excited states of open-shell systems has been nontrivial. The primary reason is that the configuration space, generated by a truncated rank of excitations from only one component of a reference multiplet, is spin-incomplete. Those "missing" configurations are of higher ranks and can, in principle, be recaptured by a particular class of excitation operators. However, the resulting formalisms are then quite involved and there are situations [e.g., time-dependent density functional theory (TD-DFT) under the adiabatic approximation] that prevent one from doing so. To solve this issue, we propose here a tensor-coupling scheme that invokes all the components of a reference multiplet (i.e., a tensor reference) rather than increases the excitation ranks. A minimal spin-adapted n-tuply excited configuration space can readily be constructed by tensor products between the n-tuple tensor excitation operators and the chosen tensor reference. Further combined with the tensor equation-of-motion formalism, very compact expressions for excitation energies can be obtained. As a first application of this general idea, a spin-adapted open-shell random phase approximation is first developed. The so-called "translation rule" is then adopted to formulate a spin-adapted, restricted open-shell Kohn-Sham (ROKS)-based TD-DFT (ROKS-TD-DFT). Here, a particular symmetry structure has to be imposed on the exchange-correlation kernel. While the standard ROKS-TD-DFT can access only excited states due to singlet-coupled single excitations, i.e., only some of the singly excited states of the same spin (S(i)) as the reference, the new scheme can capture all the excited states of spin S(i)-1, S(i), or S(i)+1 due to both singlet- and triplet-coupled single excitations. The actual implementation and computation are very much like the (spin-contaminated) unrestricted Kohn-Sham-based TD-DFT. It is also shown that spin-contaminated spin-flip configuration interaction approaches can easily be spin-adapted via the tensor-coupling scheme.

Electrical-field-induced magnetic Skyrmion ground state in a two-dimensional chromium tri-iodide ferromagnetic monolayer

NASA Astrophysics Data System (ADS)

Liu, Jie; Shi, Mengchao; Mo, Pinghui; Lu, Jiwu

2018-05-01

Using fully first-principles non-collinear self-consistent field density functional theory (DFT) calculations with relativistic spin-orbital coupling effects, we show that, by applying an out-of-plane electrical field on a free-standing two-dimensional chromium tri-iodide (CrI3) ferromagnetic monolayer, the Néel-type magnetic Skyrmion spin configurations become more energetically-favorable than the ferromagnetic spin configurations. It is revealed that the topologically-protected Skyrmion ground state is caused by the breaking of inversion symmetry, which induces the non-trivial Dzyaloshinskii-Moriya interaction (DMI) and the energetically-favorable spin-canting configuration. Combining the ferromagnetic and the magnetic Skyrmion ground states, it is shown that 4-level data can be stored in a single monolayer-based spintronic device, which is of practical interests to realize the next-generation energy-efficient quaternary logic devices and multilevel memory devices.

Ceramic applications in turbine engines

NASA Technical Reports Server (NTRS)

Byrd, J. A.; Janovicz, M. A.; Thrasher, S. R.

1981-01-01

Development testing activities on the 1900 F-configuration ceramic parts were completed, 2070 F-configuration ceramic component rig and engine testing was initiated, and the conceptual design for the 2265 F-configuration engine was identified. Fabrication of the 2070 F-configuration ceramic parts continued, along with burner rig development testing of the 2070 F-configuration metal combustor in preparation for 1132 C (2070 F) qualification test conditions. Shakedown testing of the hot engine simulator (HES) rig was also completed in preparation for testing of a spin rig-qualified ceramic-bladed rotor assembly at 1132 C (2070 F) test conditions. Concurrently, ceramics from new sources and alternate materials continued to be evaluated, and fabrication of 2070 F-configuration ceramic component from these new sources continued. Cold spin testing of the critical 2070 F-configuration blade continued in the spin test rig to qualify a set of ceramic blades at 117% engine speed for the gasifier turbine rotor. Rig testing of the ceramic-bladed gasifier turbine rotor assembly at 108% engine speed was also performed, which resulted in the failure of one blade. The new three-piece hot seal with the nickel oxide/calcium fluoride wearface composition was qualified in the regenerator rig and introduced to engine operation wiwth marginal success.

Domino model for geomagnetic field reversals.

PubMed

Mori, N; Schmitt, D; Wicht, J; Ferriz-Mas, A; Mouri, H; Nakamichi, A; Morikawa, M

2013-01-01

We solve the equations of motion of a one-dimensional planar Heisenberg (or Vaks-Larkin) model consisting of a system of interacting macrospins aligned along a ring. Each spin has unit length and is described by its angle with respect to the rotational axis. The orientation of the spins can vary in time due to spin-spin interaction and random forcing. We statistically describe the behavior of the sum of all spins for different parameters. The term "domino model" in the title refers to the interaction among the spins. We compare the model results with geomagnetic field reversals and dynamo simulations and find strikingly similar behavior. The aggregate of all spins keeps the same direction for a long time and, once in a while, begins flipping to change the orientation by almost 180 degrees (mimicking a geomagnetic reversal) or to move back to the original direction (mimicking an excursion). Most of the time the spins are aligned or antialigned and deviate only slightly with respect to the rotational axis (mimicking the secular variation of the geomagnetic pole with respect to the geographic pole). Reversals are fast compared to the times in between and they occur at random times, both in the model and in the case of the Earth's magnetic field.

CW dipolar broadening EPR spectroscopy and mechanically aligned bilayers used to measure distance and relative orientation between two TOAC spin labels on an antimicrobial peptide

NASA Astrophysics Data System (ADS)

Sahu, Indra D.; Hustedt, Eric J.; Ghimire, Harishchandra; Inbaraj, Johnson J.; McCarrick, Robert M.; Lorigan, Gary A.

2014-12-01

An EPR membrane alignment technique was applied to measure distance and relative orientations between two spin labels on a protein oriented along the surface of the membrane. Previously we demonstrated an EPR membrane alignment technique for measuring distances and relative orientations between two spin labels using a dual TOAC-labeled integral transmembrane peptide (M2δ segment of Acetylcholine receptor) as a test system. In this study we further utilized this technique and successfully measured the distance and relative orientations between two spin labels on a membrane peripheral peptide (antimicrobial peptide magainin-2). The TOAC-labeled magainin-2 peptides were mechanically aligned using DMPC lipids on a planar quartz support, and CW-EPR spectra were recorded at specific orientations. Global analysis in combination with rigorous spectral simulation was used to simultaneously analyze data from two different sample orientations for both single- and double-labeled peptides. We measured an internitroxide distance of 15.3 Å from a dual TOAC-labeled magainin-2 peptide at positions 8 and 14 that closely matches with the 13.3 Å distance obtained from a model of the labeled magainin peptide. In addition, the angles determining the relative orientations of the two nitroxides have been determined, and the results compare favorably with molecular modeling. This study demonstrates the utility of the technique for proteins oriented along the surface of the membrane in addition to the previous results for proteins situated within the membrane bilayer.

Sensitivity optimization of Bell-Bloom magnetometers by manipulation of atomic spin synchronization

NASA Astrophysics Data System (ADS)

Ranjbaran, M.; Tehranchi, M. M.; Hamidi, S. M.; Khalkhali, S. M. H.

2018-05-01

Many efforts have been devoted to the developments of atomic magnetometers for achieving the high sensitivity required in biomagnetic applications. To reach the high sensitivity, many types of atomic magnetometers have been introduced for optimization of the creation and relaxation rates of atomic spin polarization. In this paper, regards to sensitivity optimization techniques in the Mx configuration, we have proposed a novelty approach for synchronization of the spin precession in the Bell-Bloom magnetometers. We have utilized the phenomenological Bloch equations to simulate the spin dynamics when modulation of pumping light and radio frequency magnetic field were both used for atomic spin synchronization. Our results showed that the synchronization process, improved the magnetometer sensitivity respect to the classical configurations.

An MHD simulation of By-dependent magnetospheric convection and field-aligned currents during northward IMF

NASA Technical Reports Server (NTRS)

Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.

1985-01-01

A three-dimensional MHD simulation code is used to model the magnetospheric configuration when the IMF has both a northward B(z) component and a B(y) component in the east-west direction. Projections of the plasma pressure, the field-aligned velocity, the field-aligned vorticity, and the field-aligned current along the magnetic field lines into the northern ionosphere are shown and discussed. Cross-sectional patterns of these parameters are shown. The results demonstrate that the B(y) component of the IMF strongly influences the plasma sheet configuration and the magnetospheric convection pattern.

Formation, spin-up, and stability of field-reversed configurations

DOE PAGES

Omelchenko, Yuri A.

2015-08-24

Formation, spontaneous spin-up and stability of theta-pinch formed field-reversed configurations are studied self-consistently in three dimensions with a multiscale hybrid model that treats all plasma ions as full-orbit collisional macro-particles and the electrons as a massless quasineutral fluid. The end-to-end hybrid simulations for the first time reveal poloidal profiles of implosion-driven fast toroidal plasma rotation and demonstrate three well-known discharge regimes as a function of experimental parameters: the decaying stable configuration, the tilt unstable configuration and the nonlinear evolution of a fast growing tearing mode.

Asymmetric vortex pair in the wake of a circular cylinder

NASA Astrophysics Data System (ADS)

Iosilevskii, G.; Seginer, A.

1994-10-01

Stationary configurations of two asymmetric point vortices in the wake of an infinite circular cylinder, spinning or not about its axis, are analytically investigated using an ideal fluid approximation. Four different vortex configurations (patterns) in the wake of a spinning cylinder are found in the case when vortex asymmetry is weak; each configuration is associated with a certain direction of the Magnus force. The qualitative relation between a pattern and a direction of the Magnus force is in agreement with experimental data. Also obtained are asymmetrical vortex configurations in the wake of a nonspinning cylinder.

Forecasting Tidal Disruption Events for Binary Black Holes with an Outer Tertiary.

PubMed

Seto, Naoki; Kyutoku, Koutarou

2017-04-14

We discuss the gravitational wave (GW) emission and the orbital evolution of a hierarchical triple system composed of an inner binary black hole (BBH) and an outer tertiary. Depending on the kick velocity at the merger, the merged BBH could tidally disrupt the tertiary. Even though the fraction of BBH mergers accompanied by such disruptions is expected to be much smaller than unity, the existence of a tertiary and its basic parameters (e.g., semimajor axis, projected mass) can be examined for more than 10^{3} BBHs with the follow-on missions to the space GW detector LISA. This allows us to efficiently prescreen the targets for the follow-up searches for the tidal disruption events (TDEs). The TDE probability would be significantly higher for triple systems with aligned orbital- and spin-angular momenta, compared with random configurations.

Preliminary studies of a spinning tether-connected TRIO concept

NASA Astrophysics Data System (ADS)

Crellin, E. B.

1985-04-01

Use of a slowly spinning interferometer configuration with the telescopes attached to the central station using tethers of equal length, including tether configuration, mass and storage is discussed. Slow rotation allows measurements of each source at different baseline angles. When the maximum baseline length is reached, the tethers can be retracted (stopping at intermediate lengths for further measurements, if required) and the telescopes recaptured by the central station. The attitude change to another source can be performed with the rigid configuration.

Direct observation of the topological spin configurations mediated by the substitution of rare-earth element Y in MnNiGa alloy.

PubMed

Zuo, S L; Zhang, Y; Peng, L C; Zhao, X; Li, R; Li, H; Xiong, J F; He, M; Zhao, T Y; Sun, J R; Hu, F X; Shen, B G

2018-02-01

The evolution of topological magnetic domains microscopically correlates the dynamic behavior of memory units in spintronic application. Nanometric bubbles with variation of spin configurations have been directly observed in a centrosymmetric hexagonal magnet (Mn 0.5 Ni 0.5 ) 65 (Ga 1-y Y y ) 35 (y = 0.01) using Lorentz transmission electron microscopy. Magnetic bubbles instead of biskyrmions are generated due to the enhancement of quality factor Q caused by the substitution of rare-earth element Y. Furthermore, the bubble density and diversified spin configurations are systematically manipulated via combining the electric current with perpendicular magnetic fields. The magnetic bubble lattice at zero field is achieved after the optimized manipulation.

A LDA + U study of the photoemission spectra of the double hexagonal close packed phases of Am and Cm

NASA Astrophysics Data System (ADS)

Islam, M. Fhokrul; Ray, Asok K.

2010-05-01

We have investigated the photoemission spectra and other electronic structure properties such as equilibrium volume and bulk modulus of double hexagonal close packed (dhcp) americium and the density of states (DOS) and magnetic properties of dhcp curium using the LDA+U method. Our calculations show that spin polarized americium is energetically favorable but spin degenerate configuration produces experimental quantities significantly better than those calculated using the spin polarized configuration. The density of states calculated using LDA+U with both non-magnetic and spin polarized configurations is compared and the non-magnetic DOS is shown to be in good agreement with experimental photoemission spectra when U=4.5 eV. In spin polarized case, the onsite interaction parameter, U, is observed to increase the splitting between occupied and unoccupied bands by enhancing the Stoner parameter. The DOS of both non-magnetic americium and anti-ferromagnetic curium are shown to be in good agreement with that calculated using dynamical mean field theory for these two heavy actinides. For curium exchange interaction appears to play a dominant role in magnetic stability.

Iterative Magnetometer Calibration

NASA Technical Reports Server (NTRS)

Sedlak, Joseph

2006-01-01

This paper presents an iterative method for three-axis magnetometer (TAM) calibration that makes use of three existing utilities recently incorporated into the attitude ground support system used at NASA's Goddard Space Flight Center. The method combines attitude-independent and attitude-dependent calibration algorithms with a new spinning spacecraft Kalman filter to solve for biases, scale factors, nonorthogonal corrections to the alignment, and the orthogonal sensor alignment. The method is particularly well-suited to spin-stabilized spacecraft, but may also be useful for three-axis stabilized missions given sufficient data to provide observability.

Competing magnetic and spin-gapless semiconducting behavior in fully compensated ferrimagnetic CrVTiAl: Theory and experiment

NASA Astrophysics Data System (ADS)

Venkateswara, Y.; Gupta, Sachin; Samatham, S. Shanmukharao; Varma, Manoj Raama; Enamullah, Suresh, K. G.; Alam, Aftab

2018-02-01

We report the structural, magnetic, and transport properties of the polycrystalline CrVTiAl alloy along with first-principles calculations. The alloy crystallizes in a LiMgPdSn-type structure with a lattice parameter of 6.14 Å at room temperature. The absence of the (111) peak along with the presence of a weak (200) peak indicates the antisite disorder of Al with Cr and V atoms, which is different from the pure DO3 type. Magnetization measurements reveal a magnetic transition near 710 K, a coercive field of ˜100 Oe at 3 K, and a moment of ˜10-3μB/f .u . These observations are indicative of fully compensated ferrimagnetism in the alloy, which is confirmed by theoretical modeling. The temperature coefficient of resistivity is found to be negative, signaling the semiconducting nature. However, the absence of exponential dependence indicates the semiconducting nature with gapless/spin-gapless behavior. Electronic and magnetic properties of CrVTiAl for all three possible crystallographic configurations are studied theoretically. All the configurations are found to be different forms of semiconductors. The ground-state configuration is a fully compensated ferrimagnet with band gaps of 0.58 and 0.30 eV for the spin-up and -down bands, respectively. The next-higher-energy configuration is also fully compensated ferrimagnetic but has a spin-gapless semiconducting nature. The highest-energy configuration corresponds to a nonmagnetic, gapless semiconductor. The energy differences among these configurations are quite small (<1 mRy /atom ), which hints that, at finite temperatures, the alloy exists in a disordered phase, which is a mixture of the three configurations. By taking into account the theoretical and experimental findings, we conclude that CrVTiAl is a fully compensated ferrimagnet with a predominantly spin-gapless semiconducting nature.

Measurement of entanglement entropy in the two-dimensional Potts model using wavelet analysis.

PubMed

Tomita, Yusuke

2018-05-01

A method is introduced to measure the entanglement entropy using a wavelet analysis. Using this method, the two-dimensional Haar wavelet transform of a configuration of Fortuin-Kasteleyn (FK) clusters is performed. The configuration represents a direct snapshot of spin-spin correlations since spin degrees of freedom are traced out in FK representation. A snapshot of FK clusters loses image information at each coarse-graining process by the wavelet transform. It is shown that the loss of image information measures the entanglement entropy in the Potts model.

Thermoelectric efficiency enhanced in a quantum dot with polarization leads, spin-flip and external magnetic field

NASA Astrophysics Data System (ADS)

Yao, Hui; Niu, Peng-Bin; Zhang, Chao; Xu, Wei-Ping; Li, Zhi-Jian; Nie, Yi-Hang

2018-03-01

We theoretically study the thermoelectric transport properties in a quantum dot system with two ferromagnetic leads, the spin-flip scattering and the external magnetic field. The results show that the spin polarization of the leads strongly influences thermoelectric coefficients of the device. For the parallel configuration the peak of figure of merit increases with the increase of polarization strength and non-collinear configuration trends to destroy the improvement of figure of merit induced by lead polarization. While the modulation of the spin-flip scattering on the figure of merit is effective only in the absence of external magnetic field or small magnetic field. In terms of improving the thermoelectric efficiency, the external magnetic field plays a more important role than spin-flip scattering. The thermoelectric efficiency can be significantly enhanced by the magnetic field for a given spin-flip scattering strength.

Summary of flight tests to determine the spin and controllability characteristics of a remotely piloted, large-scale (3/8) fighter airplane model

NASA Technical Reports Server (NTRS)

Holleman, E. C.

1976-01-01

An unpowered, large, dynamically scaled airplane model was test flown by remote pilot to investigate the stability and controllability of the configuration at high angles of attack. The configuration proved to be departure/spin resistant; however, spins were obtained by using techniques developed on a flight support simulator. Spin modes at high and medium high angles of attack were identified, and recovery techniques were investigated. A flight support simulation of the airplane model mechanized with low speed wind tunnel data over an angle of attack range of + or - 90 deg. and an angle of sideslip range of + or - 40 deg. provided insight into the effects of altitude, stability, aerodynamic damping, and the operation of the augmented flight control system on spins. Aerodynamic derivatives determined from flight maneuvers were used to correlate model controllability with two proposed departure/spin design criteria.

Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

NASA Astrophysics Data System (ADS)

Liska, M.; Hesp, C.; Tchekhovskoy, A.; Ingram, A.; van der Klis, M.; Markoff, S.

2018-02-01

Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g. angular momentum transport and jet formation) is poorly understood. Using our new GPU-accelerated code H-AMR, we performed 3D general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning BHs, at the highest resolution to date. We explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the BH, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the BH). If strong large-scale magnetic flux reaches the BH, it bends the inner few gravitational radii of the disc and jets into partial alignment with the BH spin. On longer time-scales, the simulated disc-jet system as a whole undergoes Lense-Thirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. When the disc turbulence is well resolved, our isolated discs spread out, causing both the alignment and precession to slow down.

Cosmic Vorticity and the Origin Halo Spins

NASA Astrophysics Data System (ADS)

Libeskind, Noam I.; Hoffman, Yehuda; Steinmetz, Matthias; Gottlöber, Stefan; Knebe, Alexander; Hess, Steffen

2013-04-01

In the standard model of cosmology, structure emerges out of a non-rotational flow and the angular momentum of collapsing halos is induced by tidal torques. The growth of angular momentum in the linear and quasi-linear phases is associated with a shear, curl-free, flow and it is well described within the linear framework of tidal torque theory (TTT). However, TTT ceases to be applicable as halos approach turnaround when their ambient flow field becomes rotational. Subsequently, halos become embedded in a vortical flow field and the growth of their angular momentum is affected by the vorticity of their ambient velocity field. Using a cosmological simulation, we have examined the importance of the curl of the velocity field in determining halo spin, finding a significant alignment between the two: the vorticity tends to be perpendicular to the axis of the fastest collapse of the velocity shear tensor (e 1). This is independent of halo masses and cosmic web environment. Our results agree with previous findings on the tendency of halo spin to be perpendicular to e 1, and of the spin of (simulated) halos and (observed) galaxies to be aligned with the large-scale structure. It follows that angular momentum growth proceeds in two distinct phases. First, the angular momentum emerges out of a shear, curl-free, potential flow, as described by TTT. In the second phase, in which halos approach virialization, the angular momentum emerges out of a vortical flow and halo spin becomes partially aligned with the vorticity of the ambient flow field.

Magnon Hall effect without Dzyaloshinskii-Moriya interaction.

PubMed

Owerre, S A

2017-01-25

Topological magnon bands and magnon Hall effect in insulating collinear ferromagnets are induced by the Dzyaloshinskii-Moriya interaction (DMI) even at zero magnetic field. In the geometrically frustrated star lattice, a coplanar/noncollinear [Formula: see text] magnetic ordering may be present due to spin frustration. This magnetic structure, however, does not exhibit topological magnon effects even with DMI in contrast to collinear ferromagnets. We show that a magnetic field applied perpendicular to the star plane induces a non-coplanar spin configuration with nonzero spin scalar chirality, which provides topological effects without the need of DMI. The non-coplanar spin texture originates from the topology of the spin configurations and does not need the presence of DMI or magnetic ordering, which suggests that this phenomenon may be present in the chiral spin liquid phases of frustrated magnetic systems. We propose that these anomalous topological magnon effects can be accessible in polymeric iron (III) acetate-a star-lattice antiferromagnet with both spin frustration and long-range magnetic ordering.

Simulation Study on Understanding the Spin Transport in MgO Adsorbed Graphene Based Magnetic Tunnel Junction

NASA Astrophysics Data System (ADS)

Raturi, Ashish; Choudhary, Sudhanshu

2016-11-01

First principles calculations of spin-dependent electronic transport properties of magnetic tunnel junction (MTJ) consisting of MgO adsorbed graphene nanosheet sandwiched between two CrO2 half-metallic ferromagnetic (HMF) electrodes is reported. MgO adsorption on graphene opens bandgap in graphene nanosheet which makes it more suitable for use as a tunnel barrier in MTJs. It was found that MgO adsorption suppresses transmission probabilities for spin-down channel in case of parallel configuration (PC) and also suppresses transmission in antiparallel configuration (APC) for both spin-up and spin-down channel. Tunnel magneto-resistance (TMR) of 100% is obtained at all bias voltages in MgO adsorbed graphene-based MTJ which is higher than that reported in pristine graphene-based MTJ. HMF electrodes were found suitable to achieve perfect spin filtration effect and high TMR. I-V characteristics for both parallel and antiparallel magnetization states of junction are calculated. High TMR suggests its usefulness in spin valves and other spintronics-based applications.

Theoretical study on the magnetic moments formation in Ta-doped anatase TiO2

NASA Astrophysics Data System (ADS)

Bupu, A.; Majidi, M. A.; Rusydi, A.

2017-04-01

We present a theoretical study on Ti-vacancy induced ferromagnetism in Ta-doped anatase TiO2. Experimental study of Ti1-x Ta x O2 thin film has shown that Ti-vacancies (assisted by Ta doping) induce the formation of localized magnetic moment around it, then, the observed ferromagnetism is caused by the alignment of localized magnetic moments through Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. In this study, we focus on the formation of the localized magnetic moments in this system. We hypothesize that on a unit cell, Ti-vacancy has caused four electrons from the surrounding oxygen atoms to become unpaired. These unpaired electrons then arrange themselves into a configuration with a non-zero net magnetic moment. To examine our hypothesis, we construct a Hamiltonian of the four unpaired electrons, incorporating the Coulomb intra- and inter-orbital interactions, in matrix form. Using a set of chosen parameter values, we diagonalize the Hamiltonian to get the eigenstates and eigenvalues, then, with the resulting eigenstates, we calculate the magnetic moment, μ, by obtaining the expectation value of the square of total spin operator. Our calculation results show that in the ground state, provided that the ratio of parameters satisfies some criterion, μ ≈ 4μ B , corresponding to the four electron spins being almost perfectly aligned, can be achieved. Further, as long as we keep the Coulomb intra-orbital interaction between 0.5 and 1 eV, we find that μ ≈ 4μ B is robust up to far above room temperature. Our results demonstrate that Ti vacancies in anatase TiO2 can form very stable localized magnetic moments.

Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning

NASA Technical Reports Server (NTRS)

Smelyanskiy, V. N.; Toussaint, U. V.; Timucin, D. A.

2002-01-01

We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum excitation gap. g min, = O(n 2(exp -n/2), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to 'the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.

Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning

NASA Technical Reports Server (NTRS)

Smelyanskiy, Vadius; vonToussaint, Udo V.; Timucin, Dogan A.; Clancy, Daniel (Technical Monitor)

2002-01-01

We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum exitation gap, gmin = O(n2(sup -n/2)), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.

Linear Tidal Vestige Found in the WM Sheet

NASA Astrophysics Data System (ADS)

Lee, Jounghun; Kim, Suk; Rey, Soo-Chang

2018-06-01

We present a vestige of the linear tidal influence on the spin orientations of the constituent galaxies of the WM sheet discovered in the vicinity of the Virgo Cluster and the Local Void. The WM sheet is chosen as an optimal target since it has a rectangular parallelepiped-like shape whose three sides are in parallel with the supergalactic Cartesian axes. Determining three probability density functions of the absolute values of the supergalactic Cartesian components of the spin vectors of the WM sheet galaxies, we investigate their alignments with the principal directions of the surrounding large-scale tidal field. When the WM sheet galaxies located in the central region within the distance of 2 h ‑1 Mpc are excluded, the spin vectors of the remaining WM sheet galaxies are found to be weakly aligned, strongly aligned, and strongly anti-aligned with the minor, intermediate, and major principal directions of the surrounding large-scale tidal field, respectively. To examine whether or not the origin of the observed alignment tendency from the WM sheet is the linear tidal effect, we infer the eigenvalues of the linear tidal tensor from the axial ratios of the WM sheet with the help of the Zeldovich approximation and conduct a full analytic evaluation of the prediction of the linear tidal torque model for the three probability density functions. A detailed comparison between the analytical and the observational results reveals a good quantitative agreement not only in the behaviors but also in the amplitudes of the three probability density functions.

High spin states of 72-74Kr

NASA Astrophysics Data System (ADS)

Kaushik, M.; Kumawat, M.; Singh, U. K.; Saxena, G.

2018-05-01

A theoretical investigation has made on the structure of high spin states of 72-74Kr within the framework of cranked Hartree-Fock-Bogoliubov (CHFB) theory employing a pairing + quadrupole + hexadecapole model interaction. Dependence of shape with the spin, excitation energy, alignment of proton as well as neutron 0g9/2 orbital along with backbending phenomenon are discussed upto a high spin J = 26. We found reasonable agreement with the experimental values and other theoretical calculations.

FPGA-based protein sequence alignment : A review

NASA Astrophysics Data System (ADS)

Isa, Mohd. Nazrin Md.; Muhsen, Ku Noor Dhaniah Ku; Saiful Nurdin, Dayana; Ahmad, Muhammad Imran; Anuar Zainol Murad, Sohiful; Nizam Mohyar, Shaiful; Harun, Azizi; Hussin, Razaidi

2017-11-01

Sequence alignment have been optimized using several techniques in order to accelerate the computation time to obtain the optimal score by implementing DP-based algorithm into hardware such as FPGA-based platform. During hardware implementation, there will be performance challenges such as the frequent memory access and highly data dependent in computation process. Therefore, investigation in processing element (PE) configuration where involves more on memory access in load or access the data (substitution matrix, query sequence character) and the PE configuration time will be the main focus in this paper. There are various approaches to enhance the PE configuration performance that have been done in previous works such as by using serial configuration chain and parallel configuration chain i.e. the configuration data will be loaded into each PEs sequentially and simultaneously respectively. Some researchers have proven that the performance using parallel configuration chain has optimized both the configuration time and area.

Atomic alignment effect on reactivity and on product alignment in the energy-transfer reaction of oriented Ar (3P2, 4s [3/2]2, M(J) = 2) + Kr (4p6, 1S0) → Ar (3p6, 1S0) + Kr (5p [3/2]2).

PubMed

Ohoyama, H

2015-03-12

Steric effect for the formation of Kr (5p [3/2]₂) in the energy transfer reaction of Ar (³P₂, 4s [3/2]₂) + Kr has been studied by using an oriented Ar (³P₂, 4s [3/2]₂, M(J) = 2) beam at a collision energy of ∼0.09 eV. The emission intensity of Kr (5p [3/2]₂) is ca. 2 times enhanced when the angular momentum (J(Ar)) of Ar (³P₂) is aligned perpendicular to the relative velocity vector (v(R)). In addition, the Kr (5p [3/2]₂) emission is highly polarized parallel to v(R) (I(∥)/I(⊥) ∼ 1.2) when JAr is aligned perpendicular to v(R). The observed polarization moments indicate that the alignment of the unpaired Ar (3p) orbital of Ar (³P₂) to v(R), (Σ (|L′| = 0), Π (|L′| = 1)), dominates the energy transfer probability (σ(Π)(∥): σ(Σ)(∥): σ(Π)(⊥): σ(Σ)(⊥) = 0.49:1.33:0.55:1.23) and also the alignment of the Kr (5p) orbital of Kr (5p [3/2]₂) to v(R): the Σ-configuration of the Ar (3p) orbital leads to the parallel alignment (Σ-configuration) of the Kr(5p) orbital to v(R), conversely, the Π-configuration of Ar (3p) orbital leads to the perpendicular alignment (Π-configuration) of the Kr(5p) orbital. In addition, the selectivity of the alignment of the Kr (5p) orbital turns out to vary from perpendicular to parallel as the collision energy increases after a threshold down to 0.03 eV.

Monte Carlo simulations of ABC stacked kagome lattice films

NASA Astrophysics Data System (ADS)

Yerzhakov, H. V.; Plumer, M. L.; Whitehead, J. P.

2016-05-01

Properties of films of geometrically frustrated ABC stacked antiferromagnetic kagome layers are examined using Metropolis Monte Carlo simulations. The impact of having an easy-axis anisotropy on the surface layers and cubic anisotropy in the interior layers is explored. The spin structure at the surface is shown to be different from that of the bulk 3D fcc system, where surface axial anisotropy tends to align spins along the surface [1 1 1] normal axis. This alignment then propagates only weakly to the interior layers through exchange coupling. Results are shown for the specific heat, magnetization and sub-lattice order parameters for both surface and interior spins in three and six layer films as a function of increasing axial surface anisotropy. Relevance to the exchange bias phenomenon in IrMn3 films is discussed.

The hierarchical nature of the spin alignment of dark matter haloes in filaments

NASA Astrophysics Data System (ADS)

Aragon-Calvo, M. A.; Yang, Lin Forrest

2014-05-01

Dark matter haloes in cosmological filaments and walls have (in average) their spin vector aligned with their host structure. While haloes in walls are aligned with the plane of the wall independently of their mass, haloes in filaments present a mass-dependent two-regime orientation. Here, we show that the transition mass determining the change in the alignment regime (from parallel to perpendicular) depends on the hierarchical level in which the halo is located, reflecting the hierarchical nature of the Cosmic Web. By explicitly exposing the hierarchical structure of the Cosmic Web, we are able to identify the contributions of different components of the filament network to the alignment signal. We propose a unifying picture of angular momentum acquisition that is based on the results presented here and previous results found by other authors. In order to do a hierarchical characterization of the Cosmic Web, we introduce a new implementation of the multiscale morphology filter, the MMF-2, that significantly improves the identification of structures and explicitly describes their hierarchy. L36

How the cosmic web induces intrinsic alignments of galaxies

NASA Astrophysics Data System (ADS)

Codis, S.; Dubois, Y.; Pichon, C.; Devriendt, J.; Slyz, A.

2016-10-01

Intrinsic alignments are believed to be a major source of systematics for future generation of weak gravitational lensing surveys like Euclid or LSST. Direct measurements of the alignment of the projected light distribution of galaxies in wide field imaging data seem to agree on a contamination at a level of a few per cent of the shear correlation functions, although the amplitude of the effect depends on the population of galaxies considered. Given this dependency, it is difficult to use dark matter-only simulations as the sole resource to predict and control intrinsic alignments. We report here estimates on the level of intrinsic alignment in the cosmological hydrodynamical simulation Horizon-AGN that could be a major source of systematic errors in weak gravitational lensing measurements. In particular, assuming that the spin of galaxies is a good proxy for their ellipticity, we show how those spins are spatially correlated and how they couple to the tidal field in which they are embedded. We will also present theoretical calculations that illustrate and qualitatively explain the observed signals.

Relationship Between Magnitude of Applied Spin Recovery Moment and Ensuing Number of Recovery Turns

NASA Technical Reports Server (NTRS)

Anglin, Ernie L.

1967-01-01

An analytical study has been made to investigate the relationship between the magnitude of the applied spin recovery moment and the ensuing number of turns made during recovery from a developed spin with a view toward determining how to interpolate or extrapolate spin recovery results with regard to determining the amount of control required for a satisfactory recovery. Five configurations were used which are considered to be representative of modern airplanes: a delta-wing fighter, a stub-wing research vehicle, a boostglide configuration, a supersonic trainer, and a sweptback-wing fighter. The results obtained indicate that there is a direct relationship between the magnitude of the applied spin recovery moments and the ensuing number of recovery turns made and that this relationship can be expressed in either simple multiplicative or exponential form. Either type of relationship was adequate for interpolating or extrapolating to predict turns required for recovery with satisfactory accuracy for configurations having relatively steady recovery motions. Any two recoveries from the same developed spin condition can be used as a basis for the predicted results provided these recoveries are obtained with the same ratio of recovery control deflections. No such predictive method can be expected to give satisfactory results for oscillatory recoveries.

A magnetic phase-transition graphene transistor with tunable spin polarization

NASA Astrophysics Data System (ADS)

Vancsó, Péter; Hagymási, Imre; Tapasztó, Levente

2017-06-01

Graphene nanoribbons (GNRs) have been proposed as potential building blocks for field effect transistor (FET) devices due to their quantum confinement bandgap. Here, we propose a novel GNR device concept, enabling the control of both charge and spin signals, integrated within the simplest three-terminal device configuration. In a conventional FET device, a gate electrode is employed to tune the Fermi level of the system in and out of a static bandgap. By contrast, in the switching mechanism proposed here, the applied gate voltage can dynamically open and close an interaction gap, with only a minor shift of the Fermi level. Furthermore, the strong interplay of the band structure and edge spin configuration in zigzag ribbons enables such transistors to carry spin polarized current without employing an external magnetic field or ferromagnetic contacts. Using an experimentally validated theoretical model, we show that such transistors can switch at low voltages and high speed, and the spin polarization of the current can be tuned from 0% to 50% by using the same back gate electrode. Furthermore, such devices are expected to be robust against edge irregularities and can operate at room temperature. Controlling both charge and spin signal within the simplest FET device configuration could open up new routes in data processing with graphene based devices.

Comparison between spin-orbit torques measured by domain-wall motions and harmonic measurements

NASA Astrophysics Data System (ADS)

Kim, Joo-Sung; Nam, Yune-Seok; Kim, Dae-Yun; Park, Yong-Keun; Park, Min-Ho; Choe, Sug-Bong

2018-05-01

Here we report the comparison of the spin torque efficiencies measured by three different experimental schemes for Pt/Co/X stacks with material X (= Pt, Ta, Ti, Al, Au, Pd, and Ru. 7 materials). The first two spin torque efficiencies ɛDW (1 ) and ɛDW (2 ) are quantified by the measurement of spin-torque-induced effective field for domain-wall depinning and creeping motions, respectively. The last one—longitudinal spin torque efficiency ɛL—is measured by harmonic signal measurement of the magnetization rotation with uniform magnetization configuration. The results confirm that, for all measured Pt/Co/X stacks, ɛDW (1 ) and ɛDW (2 ) are exactly consistent to each other and these two efficiencies are roughly proportional to ɛL with proportionality constant π/2, which comes from the integration over the domain-wall configuration.

Steering Concept of a 2-Blade Heliogyro Solar Sail Spacecraft

NASA Technical Reports Server (NTRS)

Wiwattananon, Peerawan; Bryant, Robert G.

2017-01-01

Solar sails can be classified into two groups based on their method of stabilization: 1) truss supported, and 2) centrifugally (spin) supported. The truss configuration requires masts or booms to deploy, support, and rigidize the sails whereas the spin type uses the spacecraft’s centrifugal force to deploy and stabilize the sails. The truss-supported type sail has a scaling limitation because as the sail area gets larger, the sail is increasingly more difficult to make and stow: the masts and booms get heavier, occupying more volume, and have increased risk during deployment. This major disadvantage limits the size of the sail area. The spin type comes in two configurations: 1) spinning square/disk sail and 2) heliogyro sail. This spinning square/disk sail architecture suffers the same sail area limitation as the truss-supported sail.

Structure of 52 132Te80: The two-particle and two-hole spectrum of 50 132Sn82

NASA Astrophysics Data System (ADS)

Biswas, S.; Palit, R.; Navin, A.; Rejmund, M.; Bisoi, A.; Sarkar, M. Saha; Sarkar, S.; Bhattacharyya, S.; Biswas, D. C.; Caamaño, M.; Carpenter, M. P.; Choudhury, D.; Clément, E.; Danu, L. S.; Delaune, O.; Farget, F.; de France, G.; Hota, S. S.; Jacquot, B.; Lemasson, A.; Mukhopadhyay, S.; Nanal, V.; Pillay, R. G.; Saha, S.; Sethi, J.; Singh, Purnima; Srivastava, P. C.; Tandel, S. K.

2016-03-01

High-spin states in 132Te, an isotope with two proton particles and two neutron holes outside of the 132Sn doubly magic core, have been extended up to an excitation energy of 6.17 MeV. The prompt-delayed coincidence technique has been used to correlate states above the T1 /2=3.70 (9 ) μ s isomer in 132Te to the lower states using 232Th(7Li,f ) at 5.4 MeV/u and the Indian National Gamma Array (INGA). With 9Be(238U,f ) at 6.2 MeV/u and EXOGAM γ -array coupled with the VAMOS++ spectrometer, the level scheme was extended to higher excitation energies. The high-spin positive-parity states, above Jπ=10+ , in 132Te are expected to arise from the alignment of the particles in the high-j orbitals lying close to the Fermi surface, the π g7/2 2 , and the ν h11/2 -2 configurations. The experimental level scheme has been compared with the large scale shell model calculations. A reduction in the p -n interaction strength resulted in an improved agreement with the measurements up to the spin of 15 ℏ . In contrast, the comparison of the differences between the experiment and these calculations for the N =76 ,78 isotones of Te and Sn shows the increasing disagreement as a function of spin, where the magnitude is larger in Te than in Sn. This behavior could possibly be attributed to the deficiencies in the p -n correlations, in addition to the n -n correlations in Sn.

Investigation of the Possibility of Using Nuclear Magnetic Spin Alignment

NASA Technical Reports Server (NTRS)

Dent, William V., Jr.

1998-01-01

The goal of the program to investigate a "Gasdynamic fusion propulsion system for space exploration" is to develop a fusion propulsion system for a manned mission to the planet mars. A study using Deuterium and Tritium atoms are currently in progress. When these atoms under-go fusion, the resulting neutrons and alpha particles are emitted in random directions (isotropically). The probable direction of emission is equal for all directions, thus resulting in wasted energy, massive shielding and cooling requirements, and serious problems with the physics of achieving fusion. If the nuclear magnetic spin moments of the deuterium and tritium nuclei could be precisely aligned at the moment of fusion, the stream of emitted neutrons could be directed out the rear of the spacecraft for thrust and the alpha particles directed forward into an electromagnet ot produce electricity to continue operating the fusion engine. The following supporting topics are discussed: nuclear magnetic moments and spin precession in magnetic field, nuclear spin quantum mechanics, kinematics of nuclear reactions, and angular distribution of particles.

Stability Limits for Rubble Pile Asteroid Shapes

NASA Astrophysics Data System (ADS)

Scheeres, Daniel

2018-04-01

The stability of rubble pile asteroids are explored analytically, using simple models for their constituent components. Specifically, we look at the stability of spherical components resting and potentially rolling on each other as a function of their relative sizes, configuration and number. This talk will present some recent results in this problem. Of specific interest is a 5:1 limit on the elongation of a rubble pile body for stability, which is interestingly the same extreme elongation found for the first interstellar object. This limit is for a rubble pile consisting of stacked spheres, resting on each other in a straight line. If there are 5 or less bodies resting on each other in this configuration, there is an interval of spin rates for which the configuration is stable. If there are 6 or more bodies stacked as such, the spin rate for it to stabilize is beyond the spin rate at which it fissions. The talk will also explore additional results for different configurations of bodies resting on each other.

Spin alignment of ρ0 mesons produced in antineutrino and neutrino neon charged-current interactions

NASA Astrophysics Data System (ADS)

Wittek, W.; Guy, J.; Adeholz, M.; Allport, P.; Baton, J. P.; Berggren, M.; Bertrand, D.; Brisson, V.; Bullock, F. W.; Burkot, W.; Calicchio, M.; Clayton, E. F.; Coghen, T.; Cooper-Sarkar, A. M.; Erriquez, O.; Fitch, P. J.; Fogli-Muciaccia, M. T.; Hulth, P. O.; Jones, G. T.; Kasper, P.; Klein, H.; Marage, P.; Middleton, R. P.; Miller, D. B.; Mobayyen, M. M.; Morrison, D. R. O.; Neveu, M.; O'Neale, S. W.; Parker, M. A.; Petiau, P.; Sacton, J.; Sansum, R. A.; Schmitz, N.; Simopoulou, E.; Vallee, C.; Varvell, K.; Vayaki, A.; Venus, W.; Wachsmuth, H.; Wells, J.

1987-03-01

In a bubble chamber experiment with BEBC the spin alignment parameter η=1/2 (2ϱ00 - ϱ11 - ϱ-1-1) is measured for ϱ0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be ηv=0.48+/-0.27 (stat.)+/-0.15 (syst.) for vNe and ηv=0.12+/-0.20 (stat.)+/-0.10 (syst.) for vNe interactions Present address: University College London, London WC1E 6BT, UK.

Tunnel magnetoresistance for coherent spin-flip processes on an interacting quantum dot.

PubMed

Rudziński, W

2009-01-28

Spin-polarized electronic tunneling through a quantum dot coupled to ferromagnetic electrodes is investigated within a nonequilibrium Green function approach. An interplay between coherent intradot spin-flip transitions, tunneling processes and Coulomb correlations on the dot is studied for current-voltage characteristics of the tunneling junction in parallel and antiparallel magnetic configurations of the leads. It is found that due to the spin-flip processes electric current in the antiparallel configuration tends to the current characteristics in the parallel configuration, thus giving rise to suppression of the tunnel magnetoresistance (TMR) between the threshold bias voltages at which the dot energy level becomes active in tunneling. Also, the effect of a negative differential conductance in symmetrical junctions, splitting of the conductance peaks, significant modulation of TMR peaks around the threshold bias voltages as well as suppression of the diode-like behavior in asymmetrical junctions is discussed in the context of coherent intradot spin-flip transitions. It is also shown that TMR may be inverted at selected gate voltages, which qualitatively reproduces the TMR behavior predicted recently for temperatures in the Kondo regime, and observed experimentally beyond the Kondo regime for a semiconductor InAs quantum dot coupled to nickel electrodes.

Pinned, optically aligned diagnostic dock for use on the Z facility.

PubMed

Gomez, M R; Rochau, G A; Bailey, J E; Dunham, G S; Kernaghan, M D; Gard, P; Robertson, G K; Owen, A C; Argo, J W; Nielsen, D S; Lake, P W

2012-10-01

The pinned optically aligned diagnostic dock (PODD) is a multi-configuration diagnostic platform designed to measure x-ray emission on the Z facility. The PODD houses two plasma emission acquisition (PEA) systems, which are aligned with a set of precision machined pins. The PEA systems are modular, allowing a single diagnostic housing to support several different diagnostics. The PEA configurations fielded to date include both time-resolved and time-integrated, 1D spatially resolving, elliptical crystal spectrometers, and time-integrated, 1D spatially resolving, convex crystal spectrometers. Additional proposed configurations include time-resolved, monochromatic mirrored pinhole imagers and arrays of filtered x-ray diodes, diamond photo-conducting diode detectors, and bolometers. The versatility of the PODD system will allow the diagnostic configuration of the Z facility to be changed without significantly adding to the turn-around time of the machine. Additionally, the PODD has been designed to allow instrument setup to be completed entirely off-line, leaving only a refined alignment process to be performed just prior to a shot, which is a significant improvement over the instrument the PODD replaces. Example data collected with the PODD are presented.

Lightweight electrical connector split backshell

NASA Technical Reports Server (NTRS)

Goldman, Elliot (Inventor)

2009-01-01

An electrical connector split backshell is provided, comprising two substantially identical backshell halves. Each half includes a first side and a cam projecting therefrom along an axis perpendicular thereto, the cam having an alignment tooth with a constant radius and an engagement section with a radius that increases with angular distance from the alignment tooth. Each half further includes a second side parallel to the first side and a circular sector opening disposed in the second side, the circular sector opening including an inner surface configured as a ramp with a constant radius, the ramp being configured to engage with an engagement section of a cam of the other half, the circular sector opening further including a relieved pocket configured to receive an alignment tooth of the cam of the other half. Each half further includes a back side perpendicular to the first and second sides and a wire bundle notch disposed in the back side, the wire bundle notch configured to align with a wire bundle notch of the other half to form a wire bundle opening. The two substantially identical halves are rotatably coupled by engaging the engagement section of each half to the ramp of the other half.

Brightened spin-triplet interlayer excitons and optical selection rules in van der Waals heterobilayers

NASA Astrophysics Data System (ADS)

Yu, Hongyi; Liu, Gui-Bin; Yao, Wang

2018-07-01

We investigate the optical properties of spin-triplet interlayer excitons in heterobilayer transition metal dichalcogenides in comparison with the spin-singlet ones. Surprisingly, the optical transition dipole of the spin-triplet exciton is found to be in the same order of magnitude to that of the spin-singlet exciton, in sharp contrast to the monolayer excitons where the spin-triplet species is considered as dark compared to the singlet. Unlike the monolayer excitons whose spin-conserved (spin-flip) transition dipole can only couple to light of in-plane (out-of-plane) polarisation, such restriction is removed for the interlayer excitons due to the breaking of the out-of-plane mirror symmetry. We find that as the interlayer atomic registry changes, the optical transition dipole of interlayer exciton crosses between in-plane ones of opposite circular polarizations and the out-of-plane one for both the spin-triplet and spin-singlet species. As a result, excitons of both species have non-negligible coupling into photon modes of both in-plane and out-of-plane propagations, another sharp difference from the monolayers where the exciton couples predominantly into the out-of-plane propagation channel. At given atomic registry, the spin-triplet and spin-singlet excitons have distinct valley polarisation selection rules, allowing the selective optical addressing of both the valley configuration and the spin-singlet/triplet configuration of interlayer excitons.

Real-space observation of magnetic excitations and avalanche behavior in artificial quasicrystal lattices

DOE PAGES

Brajuskovic, V.; Barrows, F.; Phatak, C.; ...

2016-10-03

Artificial spin ice lattices have emerged as model systems for studying magnetic frustration in recent years. Most work to date has looked at periodic artificial spin ice lattices. In this paper, we observe frustration effects in quasicrystal artificial spin ice lattices that lack translational symmetry and contain vertices with different numbers of interacting elements. We find that as the lattice state changes following demagnetizing and annealing, specific vertex motifs retain low-energy configurations, which excites other motifs into higher energy configurations. In addition, we find that unlike the magnetization reversal process for periodic artificial spin ice lattices, which occurs through 1Dmore » avalanches, quasicrystal lattices undergo reversal through a dendritic 2D avalanche mechanism.« less

Efficient spin-filtering, magnetoresistance and negative differential resistance effects of a one-dimensional single-molecule magnet Mn(dmit)2-based device with graphene nanoribbon electrodes

NASA Astrophysics Data System (ADS)

Liu, N.; Liu, J. B.; Yao, K. L.

2017-12-01

We present first-principle spin-dependent quantum transport calculations in a molecular device constructed by one single-molecule magnet Mn(dmit)2 and two graphene nanoribbon electrodes. Our results show that the device could generate perfect spin-filtering performance in a certain bias range both in the parallel configuration (PC) and the antiparallel configuration (APC). At the same time, a magnetoresistance effect, up to a high value of 103%, can be realized. Moreover, visible negative differential resistance phenomenon is obtained for the spin-up current of the PC. These results suggest that our one-dimensional molecular device is a promising candidate for multi-functional spintronics devices.

Real-space observation of magnetic excitations and avalanche behavior in artificial quasicrystal lattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brajuskovic, V.; Barrows, F.; Phatak, C.

Artificial spin ice lattices have emerged as model systems for studying magnetic frustration in recent years. Most work to date has looked at periodic artificial spin ice lattices. In this paper, we observe frustration effects in quasicrystal artificial spin ice lattices that lack translational symmetry and contain vertices with different numbers of interacting elements. We find that as the lattice state changes following demagnetizing and annealing, specific vertex motifs retain low-energy configurations, which excites other motifs into higher energy configurations. In addition, we find that unlike the magnetization reversal process for periodic artificial spin ice lattices, which occurs through 1Dmore » avalanches, quasicrystal lattices undergo reversal through a dendritic 2D avalanche mechanism.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.; Meot, F.; Ptitsyn, V.

RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in the past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8×10 11 bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ringmore » in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC.« less

Magnetically aligned phospholipid bilayers in weak magnetic fields: optimization, mechanism, and advantages for X-band EPR studies.

PubMed

Cardon, Thomas B; Tiburu, Elvis K; Lorigan, Gary A

2003-03-01

Our lab is developing a spin-labeled EPR spectroscopic technique complementary to solid-state NMR studies to study the structure, orientation, and dynamics of uniaxially aligned integral membrane proteins inserted into magnetically aligned discotic phospholipid bilayers, or bicelles. The focus of this study is to optimize and understand the mechanisms involved in the magnetic alignment process of bicelle disks in weak magnetic fields. Developing experimental conditions for optimized magnetic alignment of bicelles in low magnetic fields may prove useful to study the dynamics of membrane proteins and its interactions with lipids, drugs, steroids, signaling events, other proteins, etc. In weak magnetic fields, the magnetic alignment of Tm(3+)-doped bicelle disks was thermodynamically and kinetically very sensitive to experimental conditions. Tm(3+)-doped bicelles were magnetically aligned using the following optimized procedure: the temperature was slowly raised at a rate of 1.9K/min from an initial temperature being between 298 and 307K to a final temperature of 318K in the presence of a static magnetic field of 6300G. The spin probe 3beta-doxyl-5alpha-cholestane (cholestane) was inserted into the bicelle disks and utilized to monitor bicelle alignment by analyzing the anisotropic hyperfine splitting for the corresponding EPR spectra. The phases of the bicelles were determined using solid-state 2H NMR spectroscopy and compared with the corresponding EPR spectra. Macroscopic alignment commenced in the liquid crystalline nematic phase (307K), continued to increase upon slowly raising the temperature, and was well-aligned in the liquid crystalline lamellar smectic phase (318K).

Downwind pre-aligned rotors for extreme-scale wind turbines

DOE PAGES

Loth, Eric; Steele, Adam; Qin, Chao; ...

2017-03-08

Downwind force angles are small for current turbines systems (1-5 MW) such that they may be readily accommodated by conventional upwind configurations. However, analysis indicates that extreme-scale systems (10-20 MW) will have larger angles that may benefit from downwind-aligned configurations. To examine potential rotor mass reduction, the pre-alignment concept was investigated a two-bladed configuration by keeping the structural and aerodynamic characteristics of each blade fixed (to avoids a complete blade re-design). Simulations for a 13.2 MW rated rotor at steady-state conditions show that this concept-level two-bladed design may yield 25% rotor mass savings while also reducing average blade stress overmore » all wind speeds. These results employed a pre-alignment on the basis of a wind speed of 1.25 times the rated wind speed. The downwind pre-aligned concept may also reduce damage equivalent loads on the blades by 60% for steady rated wind conditions. Even higher mass and damage equivalent load savings (relative to conventional upwind designs) may be possible for larger systems (15-20 MW) for which load-alignment angles become even larger. Furthermore, much more work is needed to determine whether this concept can be translated into a practical design that must meet a wide myriad of other criteria.« less

Downwind pre-aligned rotors for extreme-scale wind turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loth, Eric; Steele, Adam; Qin, Chao

Downwind force angles are small for current turbines systems (1-5 MW) such that they may be readily accommodated by conventional upwind configurations. However, analysis indicates that extreme-scale systems (10-20 MW) will have larger angles that may benefit from downwind-aligned configurations. To examine potential rotor mass reduction, the pre-alignment concept was investigated a two-bladed configuration by keeping the structural and aerodynamic characteristics of each blade fixed (to avoids a complete blade re-design). Simulations for a 13.2 MW rated rotor at steady-state conditions show that this concept-level two-bladed design may yield 25% rotor mass savings while also reducing average blade stress overmore » all wind speeds. These results employed a pre-alignment on the basis of a wind speed of 1.25 times the rated wind speed. The downwind pre-aligned concept may also reduce damage equivalent loads on the blades by 60% for steady rated wind conditions. Even higher mass and damage equivalent load savings (relative to conventional upwind designs) may be possible for larger systems (15-20 MW) for which load-alignment angles become even larger. Furthermore, much more work is needed to determine whether this concept can be translated into a practical design that must meet a wide myriad of other criteria.« less

Spin-stabilized magnetic levitation without vertical axis of rotation

DOEpatents

Romero, Louis [Albuquerque, NM; Christenson, Todd [Albuquerque, NM; Aaronson, Gene [Albuquerque, NM

2009-06-09

The symmetry properties of a magnetic levitation arrangement are exploited to produce spin-stabilized magnetic levitation without aligning the rotational axis of the rotor with the direction of the force of gravity. The rotation of the rotor stabilizes perturbations directed parallel to the rotational axis.

COSMIC VORTICITY AND THE ORIGIN HALO SPINS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libeskind, Noam I.; Steinmetz, Matthias; Gottloeber, Stefan

2013-04-01

In the standard model of cosmology, structure emerges out of a non-rotational flow and the angular momentum of collapsing halos is induced by tidal torques. The growth of angular momentum in the linear and quasi-linear phases is associated with a shear, curl-free, flow and it is well described within the linear framework of tidal torque theory (TTT). However, TTT ceases to be applicable as halos approach turnaround when their ambient flow field becomes rotational. Subsequently, halos become embedded in a vortical flow field and the growth of their angular momentum is affected by the vorticity of their ambient velocity field.more » Using a cosmological simulation, we have examined the importance of the curl of the velocity field in determining halo spin, finding a significant alignment between the two: the vorticity tends to be perpendicular to the axis of the fastest collapse of the velocity shear tensor (e{sub 1}). This is independent of halo masses and cosmic web environment. Our results agree with previous findings on the tendency of halo spin to be perpendicular to e{sub 1}, and of the spin of (simulated) halos and (observed) galaxies to be aligned with the large-scale structure. It follows that angular momentum growth proceeds in two distinct phases. First, the angular momentum emerges out of a shear, curl-free, potential flow, as described by TTT. In the second phase, in which halos approach virialization, the angular momentum emerges out of a vortical flow and halo spin becomes partially aligned with the vorticity of the ambient flow field.« less

Spin stability of sounding rocket secondary payloads following high velocity ejections

NASA Astrophysics Data System (ADS)

Nelson, Weston M.

The Auroral Spatial Structures Probe (ASSP) mission is a sounding rocket mission studying solar energy input to space weather. ASSP requires the high velocity ejection (up to 50 m/s) of 6 secondary payloads, spin stabilized perpendicular to the ejection velocity. The proposed scientific instrumentation depends on a high degree of spin stability, requiring a maximum coning angle of less than 5°. It also requires that the spin axis be aligned within 25° of the local magnetic field lines. The maximum velocities of current ejection methods are typically less than 10m/s, and often produce coning angles in excess of 20°. Because of this they do not meet the ASSP mission requirements. To meet these requirements a new ejection method is being developed by NASA Wallops Flight Facility. Success of the technique in meeting coning angle and B-field alignment requirements is evaluated herein by modeling secondary payload dynamic behavior using a 6-DOF dynamic simulation employing state space integration written in MATLAB. Simulation results showed that secondary payload mass balancing is the most important factor in meeting stability requirements. Secondary mass payload properties will be measured using an inverted torsion pendulum. If moment of inertia measurement errors can be reduced to 0.5%, it is possible to achieve mean coning and B-field alignment angles of 2.16° and 2.71°, respectively.

SU(4) Kondo effect in double quantum dots with ferromagnetic leads

NASA Astrophysics Data System (ADS)

Weymann, Ireneusz; Chirla, Razvan; Trocha, Piotr; Moca, Cǎtǎlin Paşcu

2018-02-01

We investigate the spin-resolved transport properties, such as the linear conductance and the tunnel magnetoresistance, of a double quantum dot device attached to ferromagnetic leads and look for signatures of the SU (4 ) symmetry in the Kondo regime. We show that the transport behavior greatly depends on the magnetic configuration of the device, and the spin-SU(2) as well as the orbital and spin-SU(4) Kondo effects become generally suppressed when the magnetic configuration of the leads varies from the antiparallel to the parallel one. Furthermore, a finite spin polarization of the leads lifts the spin degeneracy and drives the system from the SU(4) to an orbital-SU(2) Kondo state. We analyze in detail the crossover and show that the Kondo temperature between the two fixed points has a nonmonotonic dependence on the degree of spin polarization of the leads. In terms of methods used, we characterize transport by using a combination of analytical and numerical renormalization group approaches.

Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials.

PubMed

Chattopadhyaya, Surya; Nath, Abhijit; Das, Kalyan Kumar

2014-04-24

Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nutzman, Philip A.; Fabrycky, Daniel C.; Fortney, Jonathan J., E-mail: pnutzman@ucolick.org

Spectroscopic follow-up of dozens of transiting planets has revealed the degree of alignment between the equators of stars and the orbits of the planets they host. Here we determine a method, applicable to spotted stars, that can reveal the same information from the photometric discovery data, with no need for follow-up. A spot model fit to the global light curve, parameterized by the spin orientation of the star, predicts when the planet will transit the spots. Observing several spot crossings during different transits then leads to constraints on the spin-orbit alignment. In cases where stellar spots are small, the stellarmore » inclination, i{sub s} , and hence the true alignment, rather than just the sky projection, can be obtained. This method has become possible with the advent of space telescopes such as CoRoT and Kepler, which photometrically monitor transiting planets over a nearly continuous, long time baseline. We apply our method to CoRoT-2 and find the projected spin-orbit alignment angle, {lambda} = 4.{sup 0}7 {+-} 12.{sup 0}3, in excellent agreement with a previous determination that employed the Rossiter-McLaughlin effect. The large spots of the parent star, CoRoT-2, limit our precision on i{sub s} : 84{sup 0} {+-} 36{sup 0}, where i{sub s} < 90{sup 0}(> 90{sup 0}) indicates that the rotation axis is tilted toward (away from) the line of sight.« less

The influence of wing, fuselage and tail design on rotational flow aerodynamics data obtained beyond maximum lift with general aviation configurations

NASA Technical Reports Server (NTRS)

Bihrle, W., Jr.; Bowman, J. S., Jr.

1980-01-01

The NASA Langley Research Center has initiated a broad general aviation stall/spin research program. A rotary balance system was developed to support this effort. Located in the Langley spin tunnel, this system makes it possible to identify an airplane's aerodynamic characteristics in a rotational flow environment, and thereby permits prediction of spins. This paper presents a brief description of the experimental set-up, testing technique, five model programs conducted to date, and an overview of the rotary balance results and their correlation with spin tunnel free-spinning model results. It is shown, for example, that there is a large, nonlinear dependency of the aerodynamic moments on rotational rate and that these moments are pronouncedly configuration-dependent. Fuselage shape, horizontal tail and, in some instances, wing location are shown to appreciably influence the yawing moment characteristics above an angle of attack of 45 deg.

Searching for a 4 α linear-chain structure in excited states of 16O with covariant density functional theory

NASA Astrophysics Data System (ADS)

Yao, J. M.; Itagaki, N.; Meng, J.

2014-11-01

A study of the 4 α linear-chain structure in high-lying collective excitation states of 16O with covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with the generator coordinate method. The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found a rotational band at low spin with the dominant intrinsic configuration considered to be the one whereby 4 α clusters stay along a common axis. The strongly deformed rod shape also appears in the high-spin region with the angular momentum 13 ℏ to18 ℏ ; however, whether the state is a pure 4 α linear chain is less obvious than for the low-spin states.

Cyanide-bridged decanuclear cobalt-iron cage.

PubMed

Shiga, Takuya; Tetsuka, Tamaki; Sakai, Kanae; Sekine, Yoshihiro; Nihei, Masayuki; Newton, Graham N; Oshio, Hiroki

2014-06-16

A cyanide-bridged decanuclear [Co6Fe4] cluster was synthesized by a one-pot reaction, and the magnetic properties and electronic configuration were investigated. The complex displayed thermally controlled electron-transfer-coupled spin transition (ETCST) behavior between Co(III) low-spin-NC-Fe(II) low-spin and Co(II) high-spin-NC-Fe(III) low-spin states, as confirmed by single-crystal X-ray, magnetic, and Mössbauer analyses.

High-order moments of spin-orbit energy in a multielectron configuration

NASA Astrophysics Data System (ADS)

Na, Xieyu; Poirier, M.

2016-07-01

In order to analyze the energy-level distribution in complex ions such as those found in warm dense plasmas, this paper provides values for high-order moments of the spin-orbit energy in a multielectron configuration. Using second-quantization results and standard angular algebra or fully analytical expressions, explicit values are given for moments up to 10th order for the spin-orbit energy. Two analytical methods are proposed, using the uncoupled or coupled orbital and spin angular momenta. The case of multiple open subshells is considered with the help of cumulants. The proposed expressions for spin-orbit energy moments are compared to numerical computations from Cowan's code and agree with them. The convergence of the Gram-Charlier expansion involving these spin-orbit moments is analyzed. While a spectrum with infinitely thin components cannot be adequately represented by such an expansion, a suitable convolution procedure ensures the convergence of the Gram-Charlier series provided high-order terms are accounted for. A corrected analytical formula for the third-order moment involving both spin-orbit and electron-electron interactions turns out to be in fair agreement with Cowan's numerical computations.

Strong Effect of Azodye Layer Thickness on RM-Stabilized Photoalignment

DTIC Science & Technology

2017-05-21

to thicker layers (~40 nm). Author Keywords photoalignment; azodye; reactive mesogen 1. Introduction Photoalignment of liquid crystals by azodye...Polymerizable azodyes[3] as well as passivation of the azodye film by spin-coating with a layer of reactive mesogen[4] are currently proposed solutions...thick alignment film rather than a ~40 nm thick alignment film ; cells with thin alignment layers are stable to exposure to polarized light for at

Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Blanchard, J. W.; Sjolander, T. F.; King, J. P.; Ledbetter, M. P.; Levine, E. H.; Bajaj, V. S.; Budker, D.; Pines, A.

2015-12-01

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from the effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultralow-field NMR measurements of residual dipolar couplings in acetonitrile-2-13C aligned in stretched polyvinyl acetate gels. This permits the investigation of dipolar couplings as a perturbation on the indirect spin-spin J coupling in the absence of an applied magnetic field. As a consequence of working at zero magnetic field, we observe terms of the dipole-dipole coupling Hamiltonian that are invisible in conventional high-field NMR. This technique expands the capabilities of zero- to ultralow-field NMR and has potential applications in precision measurement of subtle physical interactions, chemical analysis, and characterization of local mesoscale structure in materials.

Orbital loop currents in iron-based superconductors

NASA Astrophysics Data System (ADS)

Klug, Markus; Kang, Jian; Fernandes, Rafael M.; Schmalian, Jörg

2018-04-01

We show that the antiferromagnetic state commonly observed in the phase diagrams of the iron-based superconductors necessarily triggers loop currents characterized by charge transfer between different Fe 3 d orbitals. This effect is rooted on the glide-plane symmetry of these materials and on the existence of an atomic spin-orbit coupling that couples states at the X and Y points of the 1-Fe Brillouin zone. In the particular case in which the magnetic moments are aligned parallel to the magnetic ordering vector direction, which is the moment configuration most commonly found in the iron-based superconductors, these loop currents involve the dx y orbital and either the dy z orbital (if the moments point along the y axis) or the dx z orbitals (if the moments point along the x axis). We show that the two main manifestations of the orbital loop currents are the emergence of magnetic moments in the pnictide/chalcogen site and an orbital-selective band splitting in the magnetically ordered state, both of which could be detected experimentally. Our results highlight the unique intertwining between orbital and spin degrees of freedom in the iron-based superconductors, and reveal the emergence of an unusual correlated phase that may impact the normal state and superconducting properties of these materials.

Two-dimensional Magnetism in Arrays of Superconducting Rings

NASA Astrophysics Data System (ADS)

Reich, Daniel H.

1996-03-01

An array of superconducting rings in an applied field corresponding to a flux of Φ0 /2 per ring behaves like a 2D Ising antiferromagnet. Each ring has two energetically equivalent states with equal and opposite magnetic moments due to fluxoid quantization, and the dipolar coupling between rings favors antiparallel alignment of the moments. Using SQUID magnetometry and scanning Hall probe microscopy, we have studied the dynamics and magnetic configurations of micron-size aluminum rings on square, triangular, honeycomb, and kagomé lattices. We have found that there are significant antiferromagnetic correlations between rings, and that effects of geometrical frustration can be observed on the triangular and kagomé lattices. Long range correlations on the other lattices are suppressed by the analog of spin freezing that locks the rings in metastable states at low temperatures, and by quenched disorder due to imperfections in the fabrication. This disorder produces a roughly 1% variation in the rings' areas, which translates into an effective random field on the spins. The ring arrays are thus an extremely good realization of the 2D random-field Ising model. (Performed in collaboration with D. Davidović, S. Kumar, J. Siegel, S. B. Field, R. C. Tiberio, R. Hey, and K. Ploog.) (Supported by NSF grants DMR-9222541, and DMR-9357518, and by the David and Lucile Packard Foundation.)

State diagram of magnetostatic coupling phase-locked spin-torque oscillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Mengwei; Wang, Longze; Wei, Dan, E-mail: weidan@mail.tsinghua.edu.cn

2015-05-07

The state diagram of magnetostatic coupling phase-locked spin torque oscillator (STO) with perpendicular reference layer and planar field generation layer (FGL) is studied by the macrospin model and the micromagnetic model. The state diagrams of current densities are calculated under various external fields. The simulation shows that there are two phase-lock current density regions. In the phase-locked STOs in low current region I, the spin configuration of FGL is uniform; in high current region II, the spin configuration of FGL is highly nonuniform. In addition, the results with different STOs separation L{sub s} are compared, and the coupling between twomore » STOs is largely decreased when L{sub s} is increased from 40 nm to 60 nm.« less

Gravitational waveforms from unequal-mass binaries with arbitrary spins under leading order spin-orbit coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tessmer, Manuel

This paper generalizes the structure of gravitational waves from orbiting spinning binaries under leading order spin-orbit coupling, as given in the work by Koenigsdoerffer and Gopakumar [Phys. Rev. D 71, 024039 (2005)] for single-spin and equal-mass binaries, to unequal-mass binaries and arbitrary spin configurations. The orbital motion is taken to be quasicircular and the fractional mass difference is assumed to be small against one. The emitted gravitational waveforms are given in analytic form.

Tunable Magnetic Alignment between Trapped Exciton-Polariton Condensates.

PubMed

Ohadi, H; Del Valle-Inclan Redondo, Y; Dreismann, A; Rubo, Y G; Pinsker, F; Tsintzos, S I; Hatzopoulos, Z; Savvidis, P G; Baumberg, J J

2016-03-11

Tunable spin correlations are found to arise between two neighboring trapped exciton-polariton condensates which spin polarize spontaneously. We observe a crossover from an antiferromagnetic to a ferromagnetic pair state by reducing the coupling barrier in real time using control of the imprinted pattern of pump light. Fast optical switching of both condensates is then achieved by resonantly but weakly triggering only a single condensate. These effects can be explained as the competition between spin bifurcations and spin-preserving Josephson coupling between the two condensates, and open the way to polariton Bose-Hubbard ladders.

Using ultrashort terahertz pulses to directly probe spin dynamics in insulating antiferromagnets

NASA Astrophysics Data System (ADS)

Bowlan, P.; Trugman, S. A.; Yarotski, D. A.; Taylor, A. J.; Prasankumar, R. P.

2018-05-01

Terahertz pulses are a direct and general probe of ultrafast spin dynamics in insulating antiferromagnets (AFM). This is shown by using optical-pump, THz-probe spectroscopy to directly track AFM spin dynamics in the hexagonal multiferroic HoMnO3 and the orthorhombic multiferroic TbMnO3. Our studies show that despite the different structural and spin orders in these materials, THz pulses can unambiguously resolve spin dynamics after optical photoexcitation. We believe that this approach is quite general and can be applied to a broad range of materials with different AFM spin alignments, providing a novel non-contact approach for probing AFM order with femtosecond temporal resolution.

Free-Spinning-Tunnel Tests of a 1/16-Scale Model of the Chance Vought XF5U-1 Airplane, TED No. NACA 2349

NASA Technical Reports Server (NTRS)

White, Richard P.

1947-01-01

Spin tests of a 1/16-scale model of the Chance Vought XF5U-1 airplane have been performed in the Langley 20-foot free-spinning tunnel. The effect of control position and movement upon the erect and inverted spin and recovery characteristics ae well as the effects of propellers, of stability flaps, and of various revisions to the design configuration have been determined for the normal fighter loading. The investigation also included spin recovery parachute, tumbling, and pilot-escape tests. For the original design configuration, with or without windmilling propellers, the recovery characteristics of the model were considered unsatisfactory. Increasing the maximum upward deflection of the ailavators from 45 deg to 65 deg resulted in greatly improved recovery characteristics. Dimensional revisions to the original airplane configuration, which satisfactorily improved the general spin and recovery characteristics of the model, consisted of: (1) a supplementary vertical tail 34 inches by 59 inches (full-scale) attached to a boom 80 inches aft of the trailing edge of the airplane in the plane of symmetry, (2) a large semispan undersurface spoiler placed along the airplane quarter-chord line and opened on the outboard side in a spin, or (3) two additional vertical tails 64 inches by 52 inches (full-scale) located at the tips of the ailavators. A satisfactory parachute arrangement for emergency spin recovery from demonstration spins was found to be an arrangement consisting of a 13.3-foot parachute attached by a 30-foot towline to the arresting gear mast on the airplane and opened simultaneously with an 8-foot parachute on the outboard end of the wing attached by a 3-foot towline. Tests indicated that pilot escape from a spin would be extremely hazardous unless the pilot is mechanically ejected from the cockpit. Model tumbling tests indicated that the airplane would not tumble.

Communication: Nuclear quadrupole moment-induced Cotton-Mouton effect in noble gas atoms

NASA Astrophysics Data System (ADS)

Fu, Li-juan; Rizzo, Antonio; Vaara, Juha

2013-11-01

New, high-sensitivity and high-resolution spectroscopic and imaging methods may be developed by exploiting nuclear magneto-optic effects. A first-principles electronic structure formulation of nuclear electric quadrupole moment-induced Cotton-Mouton effect (NQCME) is presented for closed-shell atoms. In NQCME, aligned quadrupole moments alter the index of refraction of the medium along with and perpendicular to the direction of nuclear alignment. The roles of basis-set convergence, electron correlation, and relativistic effects are investigated for three quadrupolar noble gas isotopes: 21Ne, 83Kr, and 131Xe. The magnitude of the resulting ellipticities is predicted to be 10-4-10-6 rad/(M cm) for fully spin-polarized nuclei. These should be detectable in the Voigt setup. Particularly interesting is the case of 131Xe, in which a high degree of spin polarization can be achieved via spin-exchange optical hyperpolarization.

Degeneracy of gravitational waveforms in the context of GW150914

NASA Astrophysics Data System (ADS)

Creswell, James; Liu, Hao; Jackson, Andrew D.; von Hausegger, Sebastian; Naselsky, Pavel

2018-03-01

We study the degeneracy of theoretical gravitational waveforms for binary black hole mergers using an aligned-spin effective-one-body model. After appropriate truncation, bandpassing, and matching, we identify regions in the mass–spin parameter space containing waveforms similar to the template proposed for GW150914, with masses m1 = 36+5‑4 Msolar and m2 = 29+4‑4 Msolar, using the cross-correlation coefficient as a measure of the similarity between waveforms. Remarkably high cross-correlations are found across broad regions of parameter space. The associated uncertanties exceed these from LIGO's Bayesian analysis considerably. We have shown that waveforms with greatly increased masses, such as m1 = 70 Msolar and m2 = 35 Msolar, and strong anti-aligned spins (χ1 = 0.95 and χ2 = ‑0.95) yield almost the same signal-to-noise ratio in the strain data for GW150914.

Giant magnetic splitting inducing near-unity valley polarization in van der Waals heterostructures.

PubMed

Nagler, Philipp; Ballottin, Mariana V; Mitioglu, Anatolie A; Mooshammer, Fabian; Paradiso, Nicola; Strunk, Christoph; Huber, Rupert; Chernikov, Alexey; Christianen, Peter C M; Schüller, Christian; Korn, Tobias

2017-11-16

Monolayers of semiconducting transition metal dichalcogenides exhibit intriguing fundamental physics of strongly coupled spin and valley degrees of freedom for charge carriers. While the possibility of exploiting these properties for information processing stimulated concerted research activities towards the concept of valleytronics, maintaining control over spin-valley polarization proved challenging in individual monolayers. A promising alternative route explores type II band alignment in artificial van der Waals heterostructures. The resulting formation of interlayer excitons combines the advantages of long carrier lifetimes and spin-valley locking. Here, we demonstrate artificial design of a two-dimensional heterostructure enabling intervalley transitions that are not accessible in monolayer systems. The resulting giant effective g factor of -15 for interlayer excitons induces near-unity valley polarization via valley-selective energetic splitting in high magnetic fields, even after nonselective excitation. Our results highlight the potential to deterministically engineer novel valley properties in van der Waals heterostructures using crystallographic alignment.

Hyperfine-Structure-Induced Depolarization of Impulsively Aligned I2 Molecules

NASA Astrophysics Data System (ADS)

Thomas, Esben F.; Søndergaard, Anders A.; Shepperson, Benjamin; Henriksen, Niels E.; Stapelfeldt, Henrik

2018-04-01

A moderately intense 450 fs laser pulse is used to create rotational wave packets in gas phase I2 molecules. The ensuing time-dependent alignment, measured by Coulomb explosion imaging with a delayed probe pulse, exhibits the characteristic revival structures expected for rotational wave packets but also a complex nonperiodic substructure and decreasing mean alignment not observed before. A quantum mechanical model attributes the phenomena to coupling between the rotational angular momenta and the nuclear spins through the electric quadrupole interaction. The calculated alignment trace agrees very well with the experimental results.

Directionally Aligned Amorphous Polymer Chains via Electrohydrodynamic-Jet Printing: Analysis of Morphology and Polymer Field-Effect Transistor Characteristics.

PubMed

Kim, Yebyeol; Bae, Jaehyun; Song, Hyun Woo; An, Tae Kyu; Kim, Se Hyun; Kim, Yun-Hi; Park, Chan Eon

2017-11-15

Electrohydrodynamic-jet (EHD-jet) printing provides an opportunity to directly assembled amorphous polymer chains in the printed pattern. Herein, an EHD-jet printed amorphous polymer was employed as the active layer for fabrication of organic field-effect transistors (OFETs). Under optimized conditions, the field-effect mobility (μ FET ) of the EHD-jet printed OFETs was 5 times higher than the highest μ FET observed in the spin-coated OFETs, and this improvement was achieved without the use of complex surface templating or additional pre- or post-deposition processing. As the chain alignment can be affected by the surface energy of the dielectric layer in EHD-jet printed OFETs, dielectric layers with varying wettability were examined. Near-edge X-ray absorption fine structure measurements were performed to compare the amorphous chain alignment in OFET active layers prepared by EHD-jet printing and spin coating.

Relativistic fluid dynamics with spin

NASA Astrophysics Data System (ADS)

Florkowski, Wojciech; Friman, Bengt; Jaiswal, Amaresh; Speranza, Enrico

2018-04-01

Using the conservation laws for charge, energy, momentum, and angular momentum, we derive hydrodynamic equations for the charge density, local temperature, and fluid velocity, as well as for the polarization tensor, starting from local equilibrium distribution functions for particles and antiparticles with spin 1/2. The resulting set of differential equations extends the standard picture of perfect-fluid hydrodynamics with a conserved entropy current in a minimal way. This framework can be used in space-time analyses of the evolution of spin and polarization in various physical systems including high-energy nuclear collisions. We demonstrate that a stationary vortex, which exhibits vorticity-spin alignment, corresponds to a special solution of the spin-hydrodynamical equations.

Entanglement distribution in star network based on spin chain in diamond

NASA Astrophysics Data System (ADS)

Zhu, Yuan-Ming; Ma, Lei

2018-06-01

After star network of spins was proposed, generating entanglement directly through spin interactions between distant parties became possible. We propose an architecture which involves coupled spin chains based on nitrogen-vacancy centers and nitrogen defect spins to expand star network. The numerical analysis shows that the maximally achievable entanglement Em exponentially decays with the length of spin chains M and spin noise. The entanglement capability of this configuration under the effect of disorder and spin loss is also studied. Moreover, it is shown that with this kind of architecture, star network of spins is feasible in measurement of magnetic-field gradient.

Magnus effects on spinning transonic missiles

NASA Technical Reports Server (NTRS)

Seginer, A.; Rosenwasser, I.

1983-01-01

Magnus forces and moments were measured on a basic-finner model spinning in transonic flow. Spin was induced by canted fins or by full-span or semi-span, outboard and inboard roll controls. Magnus force and moment reversals were caused by Mach number, reduced spin rate, and angle of attack variations. Magnus center of pressure was found to be independent of the angle of attack but varied with the Mach number and model configuration or reduced spin rate.

The effect of electrodes on 11 acene molecular spin valve: Semi-empirical study

NASA Astrophysics Data System (ADS)

Aadhityan, A.; Preferencial Kala, C.; John Thiruvadigal, D.

2017-10-01

A new revolution in electronics is molecular spintronics, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. The key point is the creation of molecular spin valve which consists of a diamagnetic molecule in between two magnetic leads. In this paper, non-equilibrium Green's function (NEGF) combined with Extended Huckel Theory (EHT); a semi-empirical approach is used to analyse the electron transport characteristics of 11 acene molecular spin valve. We examine the spin-dependence transport on 11 acene molecular junction with various semi-infinite electrodes as Iron, Cobalt and Nickel. To analyse the spin-dependence transport properties the left and right electrodes are joined to the central region in parallel and anti-parallel configurations. We computed spin polarised device density of states, projected device density of states of carbon and the electrode element, and transmission of these devices. The results demonstrate that the effect of electrodes modifying the spin-dependence behaviours of these systems in a controlled way. In Parallel and anti-parallel configuration the separation of spin up and spin down is lager in the case of iron electrode than nickel and cobalt electrodes. It shows that iron is the best electrode for 11 acene spin valve device. Our theoretical results are reasonably impressive and trigger our motivation for comprehending the transport properties of these molecular-sized contacts.

Anisotropic interactions of a single spin and dark-spin spectroscopy in diamond

NASA Astrophysics Data System (ADS)

Epstein, R. J.; Mendoza, F. M.; Kato, Y. K.; Awschalom, D. D.

2005-11-01

Experiments on single nitrogen-vacancy (N-V) centres in diamond, which include electron spin resonance, Rabi oscillations, single-shot spin readout and two-qubit operations with a nearby13C nuclear spin, show the potential of this spin system for solid-state quantum information processing. Moreover, N-V centre ensembles can have spin-coherence times exceeding 50 μs at room temperature. We have developed an angle-resolved magneto-photoluminescence microscope apparatus to investigate the anisotropic electron-spin interactions of single N-V centres at room temperature. We observe negative peaks in the photoluminescence as a function of both magnetic-field magnitude and angle that are explained by coherent spin precession and anisotropic relaxation at spin-level anti-crossings. In addition, precise field alignment unmasks the resonant coupling to neighbouring `dark' nitrogen spins, otherwise undetected by photoluminescence. These results demonstrate the capability of our spectroscopic technique for measuring small numbers of dark spins by means of a single bright spin under ambient conditions.

Epitaxy of spin injectors and their application toward spin-polarized lasers

NASA Astrophysics Data System (ADS)

Holub, Michael A.

Spintronics is an emerging; multidisciplinary field which examines the role of electron and nuclear spin in solid-state physics. Recent experiments suggest that the spin degree of freedom may be exploited to enhance the functionality of conventional semi conductor devices. Such endeavors require methods for efficient spin injection; spin transport, and spin detection in semiconductor heterostructures. This dissertation investigates the molecular-beam epitaxial growth and properties of ferromagnetic materials for electrical spin injection. Spin-injecting contacts are incorporated into prototype spintronic devices and their performance is examined. Two classes of materials may be used for spin injection into semiconductors: dilute magnetic semiconductor and ferromagnetic metals. The low-temperature growth and properties of (Al)Gal4nAs and In(Ga)MnAs epilayers and nanostructures are investigated, and a technique for the self-organized growth of Mn-doped InAs quantum dots is developed. The epitaxial growth of (Fe,MnAs)/(Al)GaAs Schottky tunnel barriers for electron spin injection is also investigated. The spin-injection efficiency of these contacts is assessed using a spin-valve or spin-polarized light-emitting diode. Lateral MnAs/GaAs spin-valves where Schottky tunnel barriers enable all-electrical spin injection and detection are grown, fabricated, and characterized. The Rowell criteria confirm that tunneling is the dominant, transport mechanism for the Schottky tunnel contacts. A peak magnetoresistance of 3.6% at 10 K and 1.1% at 125 K are observed for a 0.5 pin channel length spin-valve. Measurements using non-local spin-valves and other control devices verify that spurious contributions from anisotropic magnetoresistance and local Hall effects are negligible. Spin-polarized lasers offer inherent polarization control, reduced chirp, and lower threshold currents and are expected to outperform their charge-based counterparts. Initial efforts to realize a spin-VCSEL utilize (Ga,Mn)As spin aligners for hole spin injection. The polarization of the laser emission is dominated by dichroic absorption in the ferromagnetic (Ga,Mn)As spin-aligner layer, which greatly complicates the verification of spin injection. Significant spin-dependent effects are observed in a spin-VCSEL utilizing epitaxially regrown Fe/AlGaAs Schottky tunnel barriers. A maximum degree of circular polarization of 23% and corresponding threshold current reduction of 11% are measured for a 15 mum Fe spin-VCSEL at 50 K. A cavity spin polarization of 16.8% is estimated from rate equation analysis.

Spinning fluids reactor

DOEpatents

Miller, Jan D; Hupka, Jan; Aranowski, Robert

2012-11-20

A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

Effect of amino on spin-dependent transport through a junction of fused oligothiophenes between graphene electrodes

NASA Astrophysics Data System (ADS)

Cao, Liemao; Li, Xiaobo; Liu, Guang; Liu, Ziran; Zhou, Guanghui

2017-05-01

The influence of chemical side groups is significant in physical or chemical understanding the transport through the single molecular junction. Motivated by the recent successful fabrication and measurement of a single organic molecule sandwiched between graphene electrodes (Prins et al., 2011), here we study the spin-dependent transport properties through a junction of a fused oligothiophenes molecule embedded between two zigzag-edged graphene nanoribbon (ZGNR) electrodes. The molecule with and without an attached amino NH2 side group is considered, respectively, and external magnetic fields or FM stripes are applied onto the ZGNRs to initially orient the magnetic alignment of the electrodes for the spin-dependent consideration. By the ab initio calculations based on the density functional theory combined with nonequilibrium Green's function formalism, we have demonstrated the remarkable difference in the spin-charge transport property between the junctions of the molecule with and without NH2 side group. In particular, the junction with side group shows more obvious NDR. In addition, it exhibits an interesting dual spin-filtering effect when the magnetic alignment in electrodes is initially antiparallel-oriented. The mechanisms of the results are revealed and discussed in terms of the spin-resolved transmission spectrum associated with the frontier molecular orbitals evolution, the molecular projected self-consistent Hamiltonian eigenvalues, and the local density of states.

Evolution of Warped Accretion Disks in Active Galactic Nuclei. I. Roles of Feeding at the Outer Boundaries

NASA Astrophysics Data System (ADS)

Li, Yan-Rong; Wang, Jian-Min; Cheng, Cheng; Qiu, Jie

2013-02-01

We investigate the alignment processes of spinning black holes and their surrounding warped accretion disks in a frame of two different types of feeding at the outer boundaries. We consider (1) fixed flows in which gas is continually fed with a preferred angular momentum, and (2) free flows in which there is no gas supply and the disks diffuse freely at their outer edges. As expected, we find that for the cases of fixed flows the black hole disk systems always align on timescales of several 106 yr, irrespective of the initial inclinations. If the initial inclination angles are larger than π/2, the black hole accretion transits from retrograde to prograde fashion, and the accreted mass onto the black holes during these two phases is comparable. On the other hand, for the cases of free flows, both alignments and anti-alignments can occur, depending on the initial inclinations and the ratios of the angular momentum of the disks to that of the black holes. In such cases, the disks will be consumed within timescales of 106 yr by black holes accreting at the Eddington limit. We propose that there is a close connection between the black hole spin and the lifetime for which the feeding persists, which determines the observable episodic lifetimes of active galactic nuclei. We conclude that careful inclusion of the disk feeding at the outer boundaries is crucial for modeling the evolution of the black hole spin.

Triaxiality and Exotic Rotations at High Spins in 134Ce

DOE PAGES

Petrache, C. M.; Guo, S.; Ayangeakaa, A. D.; ...

2016-06-06

High-spin states in Ce-134 have been investigated using the Cd-116(Ne-22,4n) reaction and the Gammasphere array. The level scheme has been extended to an excitation energy of similar to 30 MeV and spin similar to 54 (h) over bar. Two new dipole bands and four new sequences of quadrupole transitions were identified. Several new transitions have been added to a number of known bands. One of the strongly populated dipole bands was revised and placed differently in the level scheme, resolving a discrepancy between experiment and model calculations reported previously. Configurations are assigned to the observed bands based on cranked Nilsson-Strutinskymore » calculations. A coherent understanding of the various excitations, both at low and high spins, is thus obtained, supporting an interpretation in terms of coexistence of stable triaxial, highly deformed, and superdeformed shapes up to very high spins. Rotations around different axes of the triaxial nucleus, and sudden changes of the rotation axis in specific configurations, are identified, further elucidating the nature of high-spin collective excitations in the A = 130 mass region.« less

The ss(bar sign) component of the proton and the strangeness magnetic moment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riska, D. O.; Zou, B. S.

2006-07-11

The implications of the empirical indications for a positive strangeness magnetic moment on the possible configurations of the uudss(bar sign) component of the proton are analysed. A positive value for {mu}s is obtained in the ss(bar sign) configuration where the uuds subsystem is in an orbitally excited state with [4]FS[22]F[22]S flavor-spin symmetry, which is likely to have the lowest energy. The configurations in which the s-bar is orbitally excited, which include the conventional K+{lambda}0 configuration, with exception of that in which the uuds component has spin 2, yield negative values for {mu}s. The hidden strangeness analogues of recently proposed quarkmore » cluster models for the {theta}+ pentaquark give differing signs for {mu}s.« less

Polarization of Magnetic Dipole Emission and Spinning Dust Emission from Magnetic Nanoparticles

NASA Astrophysics Data System (ADS)

Hoang, Thiem; Lazarian, Alex

2016-04-01

Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is potentially an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background B-mode signal. To obtain realistic predictions for the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that thermally rotating big grains with magnetic inclusions are weakly aligned and can achieve alignment saturation when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flying magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can significantly decrease the degree of alignment of small particles from the saturation level, whereas the excitation by ion collisions can enhance the alignment of ultrasmall particles. Using the computed degrees of alignment, we predict the polarization level of MDE from free-flying magnetic nanoparticles to be rather low. Such a polarization level is within the upper limits measured for anomalous microwave emission (AME), which indicates that MDE from free-flying iron particles may not be ruled out as a source of AME. We also quantify rotational emission from free-flying iron nanoparticles with permanent magnetic moments and find that its emissivity is about one order of magnitude lower than that from spinning polycyclic aromatic hydrocarbons.

POLARIZATION OF MAGNETIC DIPOLE EMISSION AND SPINNING DUST EMISSION FROM MAGNETIC NANOPARTICLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoang, Thiem; Lazarian, Alex

2016-04-20

Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is potentially an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background B-mode signal. To obtain realistic predictions for the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that thermally rotating big grains with magnetic inclusions are weakly aligned and can achieve alignment saturation when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flyingmore » magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can significantly decrease the degree of alignment of small particles from the saturation level, whereas the excitation by ion collisions can enhance the alignment of ultrasmall particles. Using the computed degrees of alignment, we predict the polarization level of MDE from free-flying magnetic nanoparticles to be rather low. Such a polarization level is within the upper limits measured for anomalous microwave emission (AME), which indicates that MDE from free-flying iron particles may not be ruled out as a source of AME. We also quantify rotational emission from free-flying iron nanoparticles with permanent magnetic moments and find that its emissivity is about one order of magnitude lower than that from spinning polycyclic aromatic hydrocarbons.« less

Spin and charge transport across cobalt/graphene interfaces

NASA Astrophysics Data System (ADS)

Chshiev, Mairbek; Kalitsov, Alan; Mryasov, Oleg

We report ballistic calculations of in-plane and out-of-plane spin and charge transport through graphene attached to the hcp-Co electrodes. Our calculations are based on the Keldysh non-equilibrium Green Function formalism and the tight binding Hamiltonian model tailored to treat both lateral and vertical device configurations. We present results for (i) vertical device that consists of a one-side fluorinated C4F graphene sandwiched between two hcp Co electrodes and (ii) lateral device consisting of pristine graphene/C4F graphene bilayer with two top hcp-Co electrodes Our calculations predict large magnetoresistance with small resistance-area product and significant deviation from sinusoidal behavior of spin transfer torque for the vertical device configuration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, D. J. A.; Collier Cameron, A.; Enoch, B.

We present measurements of the spin-orbit alignment angle, {lambda}, for the hot Jupiter systems WASP-32, WASP-38, and HAT-P-27/WASP-40, based on data obtained using the HARPS spectrograph. We analyze the Rossiter-McLaughlin effect for all three systems and also carry out Doppler tomography for WASP-32 and WASP-38. We find that WASP-32 (T {sub eff} = 6140{sup +90} {sub -100} K) is aligned, with an alignment angle of {lambda} = 10.{sup 0}5{sup +6.4} {sub -6.5} obtained through tomography, and that WASP-38 (T {sub eff} = 6180{sup +40} {sub -60} K) is also aligned, with tomographic analysis yielding {lambda} = 7.{sup 0}5{sup +4.7} {submore » -6.1}. The latter result provides an order-of-magnitude improvement in the uncertainty in {lambda} compared to the previous analysis of Simpson et al. We are only able to loosely constrain the angle for HAT-P-27/WASP-40 (T{sub eff} = 5190{sup +160} {sub -170} K) to {lambda} = 24.{sup 0}2{sup +76.0}{sub -44.5}, owing to the poor signal-to-noise ratio of our data. We consider this result a non-detection under a slightly updated version of the alignment test of Brown et al. We place our results in the context of the full sample of spin-orbit alignment measurements, finding that they provide further support for previously established trends.« less

Effect of the intrinsic spin-orbit interaction on the tunnel magnetoresistance in graphenelike nanoflakes

NASA Astrophysics Data System (ADS)

Weymann, Ireneusz; Krompiewski, Stefan

2016-12-01

This paper is devoted to examining the effect of intrinsic spin-orbit interaction on the possible appearance of edge magnetic moments and spin-dependent transport in graphenelike nanoflakes. In the case of finite-size graphenelike nanostructures it is shown that, on one hand, energetically the most advantageous configuration corresponds to magnetic moments located at zigzag edges with the in-plane antiferromagnetic inter-edge coupling. On the other hand, the tunnel magnetoresistance and the shot noise also have thoroughly been tested both for the in-plane configuration as well as for the out-of-plane one (for comparison reasons). Transport properties are described in terms of the mean-field Kane-Mele-Hubbard model with spin mixing correlations, supplemented by additional terms describing external leads, charging energy, and lead-nanostructure tunneling. The results show that Coulomb blockade stability spectra of graphenelike nanoflakes with ferromagnetic contacts provide information on both the intrinsic spin-orbit interaction and the expected edge magnetism.

Cesium alignment produced by pumping with unpolarized light★

NASA Astrophysics Data System (ADS)

Shi, Yongqi; Weis, Antoine

2018-04-01

We demonstrate optical pumping on the four hyperfine components of the Cs D 1 transition by unpolarized (UPL) resonant laser light. The evidence is based on the reduction of the absorption coefficients κ 0 with increasing light power P in an uncoated Cs vapor cell with isotropic spin relaxation. For comparison we perform the same quantitative κ 0( P) measurements with linearly-polarized light (LPL) and circularly-polarized light (CPL). We find that our previously published algebraic expressions give an excellent description of all experimentally recorded induced transparency signals. Based on this we can make reliable absolute predictions for the power dependence of the spin orientation and alignment produced by pumping with LPL, CPL and UPL.

Vector correlation between the alignment of reactant N2 (A 3Σu+) and the alignment of product NO (A 2Σ+) rotation in the energy transfer reaction of aligned N2 (A 3Σu+) + NO (X 2Π) → NO (A 2Σ+) + N2 (X 1Σg+).

PubMed

Ohoyama, H

2013-12-21

The vector correlation between the alignment of reactant N2 (A (3)Σu(+)) and the alignment of product NO (A (2)Σ(+)) rotation has been studied in the energy transfer reaction of aligned N2 (A (3)Σu(+)) + NO (X (2)Π) → NO (A (2)Σ(+)) + N2 (X (1)Σg(+)) under the crossed beam condition at a collision energy of ~0.07 eV. NO (A (2)Σ(+)) emission in the two linear polarization directions (i.e., parallel and perpendicular with respect to the relative velocity vector v(R)) has been measured as a function of the alignment of N2 (A (3)Σu(+)) along its molecular axis in the collision frame. The degree of polarization of NO (A (2)Σ(+)) emission is found to depend on the alignment angle (θ(v(R))) of N2 (A (3)Σu(+)) in the collision frame. The shape of the steric opacity function at the two polarization conditions turns out to be extremely different from each other: The steric opacity function at the parallel polarization condition is more favorable for the oblique configuration of N2 (A (3)Σu(+)) at an alignment angle of θ(v(R)) ~ 45° as compared with that at the perpendicular polarization condition. The alignment of N2 (A (3)Σu(+)) is found to give a significant effect on the alignment of NO (A (2)Σ(+)) rotation in the collision frame: The N2 (A (3)Σu(+)) configuration at an oblique alignment angle θ(v(R)) ~ 45° leads to a parallel alignment of NO (A (2)Σ(+)) rotation (J-vector) with respect to v(R), while the axial and sideways configurations of N2 (A (3)Σu(+)) lead to a perpendicular alignment of NO (A (2)Σ(+)) rotation with respect to vR. These stereocorrelated alignments of the product rotation have a good correlation with the stereocorrelated reactivity observed in the multi-dimensional steric opacity function [H. Ohoyama and S. Maruyama, J. Chem. Phys. 137, 064311 (2012)].

Creation and Annihilation of Skyrmions in the Frustrated Magnets with Competing Exchange Interactions.

PubMed

Hu, Yong; Chi, Xiaodan; Li, Xuesi; Liu, Yan; Du, An

2017-11-22

In triangular-lattice magnets, the coexistence of third-neighbor antiferromagnetic and nearest-neighbor ferromagnetic exchange interactions can induce rich magnetic phases including noncoplanar skyrmion crystals. Based on Monte Carlo simulation, we studied the dependence of magnetic phase transition on exchange interaction strength. Under the consideration of uniaxial anisotropy and magnetic field both perpendicular to the film plane, a large antiferromagnetic exchange interaction induces a high frustration. When the value of antiferromagnetic exchange interaction is one and a half times larger than the ferromagnetic one, a magnetic phase composed of canting spin stripes, never observed in the chiral magnets, forms. Interestingly, different canting spin stripes along three 120 degree propagation directions may coexist randomly in a magnetic phase, attesting that the canting spin stripes are three-fold degenerate states akin to helices and the multiple state of canting spin stripes is a circular configuration with zero skyrmion charge number. Moreover, skyrmions and antiskyrmions can be observed simultaneously in the configuration at the low temperature nearly close to 0 K, and their configuration and diameter properties are discussed. Finally, the mechanisms of skyrmion creation and annihilation are properly interpreted by comparing exchange and Zeeman energy terms.

Perspectives of disproportionation driven superconductivity in strongly correlated 3d compounds.

PubMed

Moskvin, A S

2013-02-27

Disproportionation in 3d compounds can give rise to an unconventional electron-hole Bose liquid with a very rich phase diagram, from a Bose metal, to a charge ordering insulator and an inhomogeneous Bose-superfluid. Optimal conditions for disproportionation driven high-T(c) superconductivity are shown to be realized only for several Jahn-Teller d(n) configurations that permit the formation of well defined local composite bosons. These are the high-spin d(4), low-spin d(7), and d(9) configurations given the octahedral crystal field, and the d(1), high-spin d(6) configurations given the tetrahedral crystal field. The disproportionation reaction has a peculiar 'anti-Jahn-Teller' character lifting the bare orbital degeneracy. Superconductivity in the d(4) and d(6) systems at variance with d(1), d(7), and d(9) systems implies unavoidable coexistence of the spin-triplet composite bosons and the magnetic lattice. We argue that unconventional high-T(c) superconductivity, observed in quasi-2d cuprates with tetragonally distorted CuO(6) octahedra and iron-based layered pnictides/chalcogenides with tetrahedrally coordinated Fe(2+) ions presents a key argument to support the fact that the disproportionation scenario is at work in these compounds.

Investigation of the spin Seebeck effect and anomalous Nernst effect in a bulk carbon material

NASA Astrophysics Data System (ADS)

Wongjom, Poramed; Pinitsoontorn, Supree

2018-03-01

Since the discovery of the spin Seebeck effect (SSE) in 2008, it has become one of the most active topics in the spin caloritronics research field. It opened up a new way to create the spin current by a combination of magnetic fields and heat. The SSE was observed in many kinds of materials including metallic, semiconductor, or insulating magnets, as well as non-magnetic materials. On the other hand, carbon-based materials have become one of the most exciting research areas recently due to its low cost, abundance and some exceptional functionalities. In this work, we have investigated the possibility of the SSE in bulk carbon materials for the first time. Thin platinum film (Pt), coated on the smoothened surface of the bulk carbon, was used as the spin detector via the inverse spin Hall effect (ISHE). The experiment for observing longitudinal SSE in the bulk carbon was set up by applying a magnetic field up to 30 kOe to the sample with the direction perpendicular to the applied temperature gradient. The induced voltage from the SSE was extracted. However, for conductive materials, e.g. carbon, the voltage signal under this set up could be a combination of the SSE and the anomalous Nernst effect (ANE). Therefore, two measurement configurations were carried out, i.e. the in-plane magnetization (IM), and the perpendicular-to-plane magnetization (PM). For the IM configuration, the SSE + ANE signals were detected where as the only ANE signal existed in the PM configuration. The results showed that there were the differences between the voltage signals from the IM and PM configurations implying the possibility of the SSE in the bulk carbon material. Moreover, it was found that the difference in the IM and PM signals was a function of the magnetic field strength, temperature difference, and measurement temperature. Although the magnitude of the possible SSE voltage in this experiment was rather low (less than 0.5 μV at 50 K), this research showed that potential of using low cost and abundant bulk carbon as spin current supplier or thermoelectric power generators.

Progressive Stereo Locking (PSL): A Residual Dipolar Coupling Based Force Field Method for Determining the Relative Configuration of Natural Products and Other Small Molecules.

PubMed

Cornilescu, Gabriel; Ramos Alvarenga, René F; Wyche, Thomas P; Bugni, Tim S; Gil, Roberto R; Cornilescu, Claudia C; Westler, William M; Markley, John L; Schwieters, Charles D

2017-08-18

Establishing the relative configuration of a bioactive natural product represents the most challenging part in determining its structure. Residual dipolar couplings (RDCs) are sensitive probes of the relative spatial orientation of internuclear vectors. We adapted a force field structure calculation methodology to allow free sampling of both R and S configurations of the stereocenters of interest. The algorithm uses a floating alignment tensor in a simulated annealing protocol to identify the conformations and configurations that best fit experimental RDC and distance restraints (from NOE and J-coupling data). A unique configuration (for rigid molecules) or a very small number of configurations (for less rigid molecules) of the structural models having the lowest chiral angle energies and reasonable magnitudes of the alignment tensor are provided as the best predictions of the unknown configuration. For highly flexible molecules, the progressive locking of their stereocenters into their statistically dominant R or S state dramatically reduces the number of possible relative configurations. The result is verified by checking that the same configuration is obtained by initiating the locking from different regions of the molecule. For all molecules tested having known configurations (with conformations ranging from mostly rigid to highly flexible), the method accurately determined the correct configuration.

Magnetic vortex nucleation modes in static magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanatka, Marek; Urbanek, Michal; Jira, Roman

The magnetic vortex nucleation process in nanometer- and micrometer-sized magnetic disks undergoes several phases with distinct spin configurations called the nucleation states. Before formation of the final vortex state, small submicron disks typically proceed through the so-called C-state while the larger micron-sized disks proceed through the more complicated vortex-pair state or the buckling state. This work classifies the nucleation states using micromagnetic simulations and provides evidence for the stability of vortex-pair and buckling states in static magnetic fields using magnetic imaging techniques and electrical transport measurements. Lorentz Transmission Electron Microscopy and Magnetic Transmission X-ray Microscopy are employed to reveal themore » details of spin configuration in each of the nucleation states. We further show that it is possible to unambiguously identify these states by electrical measurements via the anisotropic magnetoresistance effect. Combination of the electrical transport and magnetic imaging techniques confirms stability of a vortex-antivortex-vortex spin configuration which emerges from the buckling state in static magnetic fields.« less

Magnetic vortex nucleation modes in static magnetic fields

DOE PAGES

Vanatka, Marek; Urbanek, Michal; Jira, Roman; ...

2017-10-03

The magnetic vortex nucleation process in nanometer- and micrometer-sized magnetic disks undergoes several phases with distinct spin configurations called the nucleation states. Before formation of the final vortex state, small submicron disks typically proceed through the so-called C-state while the larger micron-sized disks proceed through the more complicated vortex-pair state or the buckling state. This work classifies the nucleation states using micromagnetic simulations and provides evidence for the stability of vortex-pair and buckling states in static magnetic fields using magnetic imaging techniques and electrical transport measurements. Lorentz Transmission Electron Microscopy and Magnetic Transmission X-ray Microscopy are employed to reveal themore » details of spin configuration in each of the nucleation states. We further show that it is possible to unambiguously identify these states by electrical measurements via the anisotropic magnetoresistance effect. Combination of the electrical transport and magnetic imaging techniques confirms stability of a vortex-antivortex-vortex spin configuration which emerges from the buckling state in static magnetic fields.« less

Theoretical study of optical conductivity of graphene with magnetic and nonmagnetic adatoms

NASA Astrophysics Data System (ADS)

Majidi, Muhammad Aziz; Siregar, Syahril; Rusydi, Andrivo

2014-11-01

We present a theoretical study of the optical conductivity of graphene with magnetic and nonmagnetic adatoms. First, by introducing an alternating potential in a pure graphene, we demonstrate a gap formation in the density of states and the corresponding optical conductivity. We highlight the distinction between such a gap formation and the so-called Pauli blocking effect. Next, we apply this idea to graphene with adatoms by introducing magnetic interactions between the carrier spins and the spins of the adatoms. Exploring various possible ground-state spin configurations of the adatoms, we find that the antiferromagnetic configuration yields the lowest total electronic energy and is the only configuration that forms a gap. Furthermore, we analyze four different circumstances leading to similar gaplike structures and propose a means to interpret the magneticity and the possible orderings of the adatoms on graphene solely from the optical conductivity data. We apply this analysis to the recently reported experimental data of oxygenated graphene.

Equilibrium configurations of a charged fluid around a Kerr black hole

NASA Astrophysics Data System (ADS)

Trova, Audrey; Schroven, Kris; Hackmann, Eva; Karas, Vladimír; Kovář, Jiří; Slaný, Petr

2018-05-01

Equilibrium configurations of electrically charged perfect fluid surrounding a central rotating black hole endowed with a test electric charge and embedded in a large-scale asymptotically uniform magnetic field are presented. Following our previous studies considering the central black hole to be nonrotating, we show that in the rotating case conditions for the configurations existence change according to the spin of the black hole. We focus our attention on the charged fluid in rigid rotation, which can form toroidal configurations centered in the equatorial plane or the ones hovering above the black hole, along the symmetry axis. We conclude that a nonzero value of spin changes the existence conditions and the morphology of the solutions significantly. In the case of fast rotation, the morphology of the structures is close to an oblate shape.

Stability of the Euler resting N-body relative equilibria

NASA Astrophysics Data System (ADS)

Scheeres, D. J.

2018-03-01

The stability of a system of N equal-sized mutually gravitating spheres resting on each other in a straight line and rotating in inertial space is considered. This is a generalization of the "Euler Resting" configurations previously analyzed in the finite density 3 and 4 body problems. Specific questions for the general case are how rapidly the system must spin for the configuration to stabilize, how rapidly it can spin before the components separate from each other, and how these results change as a function of N. This paper shows that the Euler Resting configuration can only be stable for up to 5 bodies and that for 6 or more bodies the configuration can never be stable. This places an ideal limit of 5:1 on the aspect ratio of a rubble pile body's shape.

N=151Pu,Cm and Cf nuclei under rotational stress: Role of higher-order deformations

DOE PAGES

Hota, S. S.; Chowdhury, P.; Khoo, T. L.; ...

2014-10-18

The fast-rotating N=151 isotones 245Pu, 247Cm and 249Cf have been studied through inelastic excitation and transfer reactions with radioactive targets. While all have a ground-state band built on a νj 15/2[734]9/2 - Nilsson configuration, new excited bands have also been observed in each isotone. These odd-N excited bands allow a comparison of the alignment behavior for two different configurations, where the νj 15/2 alignment is either blocked or allowed. The effect of higher order deformations is explored through cranking calculations, which help clarify the elusive nature of νj 15/2 alignments.

Adiabatic Field-Free Alignment of Asymmetric Top Molecules with an Optical Centrifuge.

PubMed

Korobenko, A; Milner, V

2016-05-06

We use an optical centrifuge to align asymmetric top SO_{2} molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines the sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment that persists after the molecules are released from the centrifuge. The periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 deg, permanent field-free alignment offers new ways of controlling molecules with laser light.

High-field magnetization and magnetic phase diagram of α -Cu2V2O7

NASA Astrophysics Data System (ADS)

Gitgeatpong, G.; Suewattana, M.; Zhang, Shiwei; Miyake, A.; Tokunaga, M.; Chanlert, P.; Kurita, N.; Tanaka, H.; Sato, T. J.; Zhao, Y.; Matan, K.

2017-06-01

High-field magnetization of the spin-1 /2 antiferromagnet α -Cu2V2O7 was measured in pulsed magnetic fields of up to 56 T in order to study its magnetic phase diagram. When the field was applied along the easy axis (the a axis), two distinct transitions were observed at Hc 1=6.5 T and Hc 2=18.0 T. The former is a spin-flop transition typical for a collinear antiferromagnet and the latter is believed to be a spin-flip transition of canted moments. The canted moments, which are induced by the Dzyaloshinskii-Moriya interactions, anti-align for Hc 1

Spin-dependent transport through an interacting quantum dot.

PubMed

Zhang, Ping; Xue, Qi-Kun; Wang, Yupeng; Xie, X C

2002-12-31

We study the nonequilibrium spin transport through a quantum dot coupled to the magnetic electrodes. A formula for the spin-dependent current is obtained and is applied to discuss the linear conductance and magnetoresistance in the interacting regime. We show that the Kondo resonance and the correlation-induced spin splitting of the dot levels may be systematically controlled by internal magnetization in the electrodes. As a result, when the electrodes are in parallel magnetic configuration, the linear conductance is characterized by two spin-resolved peaks. Furthermore, the presence of the spin-flip process in the dot splits the Kondo resonance into three peaks.

Balancing Newtonian gravity and spin to create localized structures

NASA Astrophysics Data System (ADS)

Bush, Michael; Lindner, John

2015-03-01

Using geometry and Newtonian physics, we design localized structures that do not require electromagnetic or other forces to resist implosion or explosion. In two-dimensional Euclidean space, we find an equilibrium configuration of a rotating ring of massive dust whose inward gravity is the centripetal force that spins it. We find similar solutions in three-dimensional Euclidean and hyperbolic spaces, but only in the limit of vanishing mass. Finally, in three-dimensional Euclidean space, we generalize the two-dimensional result by finding an equilibrium configuration of a spherical shell of massive dust that supports itself against gravitational collapse by spinning isoclinically in four dimensions so its three-dimensional acceleration is everywhere inward. These Newtonian ``atoms'' illuminate classical physics and geometry.

Eating a planet and spinning up

NASA Astrophysics Data System (ADS)

Qureshi, Ahmed; Naoz, Smadar; Shkolnik, Evgenya L.

2018-01-01

One of the predictions of high eccentricity planetary migration is that many planets will end up plunging into their host stars. We investigate the consequence of planetary mergers on their stellar hosts’ spin-period. Energy and angular momentum conservation yield that a planet consumption by a star will spin-up of the star. We find that our calculations align with the observed bifurcation in the stellar spin-period in young clusters. After a Sun-like star has eaten a planet, it will then, spin down due to magnetic braking, consistent with the observed lack of fast rotators in old clusters. The agreement between the calculations presented here and the observed spin-period of stars in young clusters provides circumstantial evidence that planetary accretion onto their host stars is a generic feature in planetary-system evolution.

Control of spin ambiguity during reorientation of an energy dissipating body

NASA Technical Reports Server (NTRS)

Kaplan, M. H.; Cenker, R. J.

1973-01-01

A quasi-rigid body initially spinning about its minor principal axis and experiencing energy dissipation will enter a tumbling mode and eventually reorient itself such that stable spin about its major principal axis is achieved. However, in this final state the body may be spinning in a positive or negative sense with respect to its major axis and aligned in a positive or negative sense with the inertially fixed angular momentum vector. This ambiguity can be controlled only through an active system. The associated dynamical formulations and simulations of uncontrolled reorientations are presented. Three control schemes are discussed and results offered for specific examples. These schemes include displacement of internal masses, spinning up of internal inertia, and reaction jets, all of which have demonstrated the ability to control spin ambiguity.

Measuring Alignments between Galaxies and the Cosmic Web at z ˜ 2-3 Using IGM Tomography

NASA Astrophysics Data System (ADS)

Krolewski, Alex; Lee, Khee-Gan; Lukić, Zarija; White, Martin

2017-03-01

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (I.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ˜ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction with coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ˜ 2.5. We show that IGM tomography surveys with ≲5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, {{Δ }}< \\cos θ > , with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ˜1 deg2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with {{Δ }}< \\cos θ > ˜ 0.1, but much larger surveys encompassing >10,000 galaxies, such as Subaru PFS, will be required to constrain models with {{Δ }}< \\cos θ > ˜ 0.03. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ˜ 2, improving our understanding of the physics of intrinsic alignments.

Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krolewski, Alex; Lee, Khee-Gan; Luki?, Zarija

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction withmore » coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~ 1 deg 2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.« less

Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography

DOE PAGES

Krolewski, Alex; Lee, Khee-Gan; Luki?, Zarija; ...

2017-02-28

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction withmore » coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~ 1 deg 2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.« less

Tracking spin-axis orbital alignment in selected binary systems: the Torun Rossiter-McLaughlin effect survey

NASA Astrophysics Data System (ADS)

Sybilski, P.; Pawłaszek, R. K.; Sybilska, A.; Konacki, M.; Hełminiak, K. G.; Kozłowski, S. K.; Ratajczak, M.

2018-07-01

We have obtained high-resolution spectra of four eclipsing binary systems (FM Leo, NN Del, V963 Cen and AI Phe) with the view to gaining an insight into the relative orientations of their stellar spin axes and orbital axes. The so-called Rossiter-McLaughlin (RM) effect, i.e. the fact that the broadening and the amount of blue or redshift in the spectra during an eclipse depends on the tilt of the spin axis of the background star, has the potential of reconciling observations and theoretical models if such a tilt is found. We analyse the RM effect by disentangling the spectra, removing the front component and measuring the remaining, distorted lines with a broadening function (BF) obtained from single-value decomposition (SVD), weighting by the intensity centre of the BF in the eclipse. All but one of our objects show no significant misalignment, suggesting that aligned systems are dominant. We provide stellar as well as orbital parameters for our systems. With five measured spin-orbit angles, we increase significantly (from 9 to 14) the number of stars for which it has been measured. The spin-orbit angle β calculated for AI Phe's secondary component shows a misalignment of 87±17°. NN Del, with a large separation of components and a long dynamical time-scale for circularization and synchronization, is an example of a close to primordial spin-orbit angle measurement.

Accuracy of Binary Black Hole waveforms for Advanced LIGO searches

NASA Astrophysics Data System (ADS)

Kumar, Prayush; Barkett, Kevin; Bhagwat, Swetha; Chu, Tony; Fong, Heather; Brown, Duncan; Pfeiffer, Harald; Scheel, Mark; Szilagyi, Bela

2015-04-01

Coalescing binaries of compact objects are flagship sources for the first direct detection of gravitational waves with LIGO-Virgo observatories. Matched-filtering based detection searches aimed at binaries of black holes will use aligned spin waveforms as filters, and their efficiency hinges on the accuracy of the underlying waveform models. A number of gravitational waveform models are available in literature, e.g. the Effective-One-Body, Phenomenological, and traditional post-Newtonian ones. While Numerical Relativity (NR) simulations provide for the most accurate modeling of gravitational radiation from compact binaries, their computational cost limits their application in large scale searches. In this talk we assess the accuracy of waveform models in two regions of parameter space, which have only been explored cursorily in the past: the high mass-ratio regime as well as the comparable mass-ratio + high spin regime.s Using the SpEC code, six q = 7 simulations with aligned-spins and lasting 60 orbits, and tens of q ∈ [1,3] simulations with high black hole spins were performed. We use them to study the accuracy and intrinsic parameter biases of different waveform families, and assess their viability for Advanced LIGO searches.

Communication: Nuclear quadrupole moment-induced Cotton-Mouton effect in noble gas atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Li-juan; Vaara, Juha, E-mail: juha.vaara@iki.fi; Rizzo, Antonio

New, high-sensitivity and high-resolution spectroscopic and imaging methods may be developed by exploiting nuclear magneto-optic effects. A first-principles electronic structure formulation of nuclear electric quadrupole moment-induced Cotton-Mouton effect (NQCME) is presented for closed-shell atoms. In NQCME, aligned quadrupole moments alter the index of refraction of the medium along with and perpendicular to the direction of nuclear alignment. The roles of basis-set convergence, electron correlation, and relativistic effects are investigated for three quadrupolar noble gas isotopes: {sup 21}Ne, {sup 83}Kr, and {sup 131}Xe. The magnitude of the resulting ellipticities is predicted to be 10{sup −4}–10{sup −6} rad/(M cm) for fully spin-polarized nuclei.more » These should be detectable in the Voigt setup. Particularly interesting is the case of {sup 131}Xe, in which a high degree of spin polarization can be achieved via spin-exchange optical hyperpolarization.« less

Sealed magic angle spinning nuclear magnetic resonance probe and process for spectroscopy of hazardous samples

DOEpatents

Cho, Herman M.; Washton, Nancy M.; Mueller, Karl T.; Sears, Jr., Jesse A.; Townsend, Mark R.; Ewing, James R.

2016-06-14

A magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) probe is described that includes double containment enclosures configured to seal and contain hazardous samples for analysis. The probe is of a modular design that ensures containment of hazardous samples during sample analysis while preserving spin speeds for superior NMR performance and convenience of operation.

Exploratory study of the effects of wing-leading-edge modifications on the stall/spin behavior of a light general aviation airplane

NASA Technical Reports Server (NTRS)

1979-01-01

Configurations with full-span and segmented leading-edge flaps and full-span and segmented leading-edge droop were tested. Studies were conducted with wind-tunnel models, with an outdoor radio-controlled model, and with a full-scale airplane. Results show that wing-leading-edge modifications can produce large effects on stall/spin characteristics, particularly on spin resistance. One outboard wing-leading-edge modification tested significantly improved lateral stability at stall, spin resistance, and developed spin characteristics.

Stationary bound-state massive scalar field configurations supported by spherically symmetric compact reflecting stars

NASA Astrophysics Data System (ADS)

Hod, Shahar

2017-12-01

It has recently been demonstrated that asymptotically flat neutral reflecting stars are characterized by an intriguing no-hair property. In particular, it has been proved that these horizonless compact objects cannot support spatially regular static matter configurations made of scalar (spin-0) fields, vector (spin-1) fields and tensor (spin-2) fields. In the present paper we shall explicitly prove that spherically symmetric compact reflecting stars can support stationary (rather than static) bound-state massive scalar fields in their exterior spacetime regions. To this end, we solve analytically the Klein-Gordon wave equation for a linearized scalar field of mass μ and proper frequency ω in the curved background of a spherically symmetric compact reflecting star of mass M and radius R_{ {s}}. It is proved that the regime of existence of these stationary composed star-field configurations is characterized by the simple inequalities 1-2M/R_{ {s}}<(ω /μ )^2<1. Interestingly, in the regime M/R_{ {s}}≪ 1 of weakly self-gravitating stars we derive a remarkably compact analytical equation for the discrete spectrum {ω (M,R_{ {s}},μ )}^{n=∞}_{n=1} of resonant oscillation frequencies which characterize the stationary composed compact-reflecting-star-linearized-massive-scalar-field configurations. Finally, we verify the accuracy of the analytically derived resonance formula of the composed star-field configurations with direct numerical computations.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, Fredy L.; González, Guillermo A.

2018-07-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modelled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping, and (iii) displaying close encounters. Using the smaller alignment index chaos indicator, we further classify bounded orbits into regular, sticky, or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

Discovery of the Kinematic Alignment of Early-type Galaxies in the Virgo Cluster

NASA Astrophysics Data System (ADS)

Kim, Suk; Jeong, Hyunjin; Lee, Jaehyun; Lee, Youngdae; Joo, Seok-Joo; Kim, Hak-Sub; Rey, Soo-Chang

2018-06-01

Using the kinematic position angles (PAkin), an accurate indicator for the spin axis of a galaxy, obtained from the ATLAS3D integral-field-unit (IFU) spectroscopic data, we discovered that 57 Virgo early-type galaxies tend to prefer the specific PAkin values of 20° and 100°, suggesting that they are kinematically aligned with each other. These kinematic alignment angles are further associated with the directions of the two distinct axes of the Virgo cluster extending east–west and north–south, strongly suggesting that the two distinct axes are the filamentary structures within the cluster as a trace of infall patterns of galaxies. Given that the spin axis of a massive early-type galaxy does not change easily even in clusters from the hydrodynamic simulations, Virgo early-type galaxies are likely to fall into the cluster along the filamentary structures while maintaining their angular momentum. This implies that many early-type galaxies in clusters are formed in filaments via major mergers before subsequently falling into the cluster. Investigating the kinematic alignment in other clusters will allow us to understand the formation of galaxy clusters and early-type galaxies.

Nonreciprocity of electrically excited thermal spin signals in CoFeAl-Cu-Py lateral spin valves

NASA Astrophysics Data System (ADS)

Hu, Shaojie; Cui, Xiaomin; Nomura, Tatsuya; Min, Tai; Kimura, Takashi

2017-03-01

Electrical and thermal spin currents excited by an electric current have been systematically investigated in lateral spin valves consisting of CoFeAl and Ni80Fe20 (Py) wires bridged by a Cu strip. In the electrical spin signal, the reciprocity between the current and voltage probes was clearly confirmed. However, a significant nonreciprocity was observed in the thermal spin signal. This provides clear evidence that a large spin-dependent Seebeck coefficient is more important than the spin polarization for efficient thermal spin injection and detection. We demonstrate that the spin-dependent Seebeck coefficient can be simply evaluated from the thermal spin signals for two configurations. Our experimental description paves a way for evaluating a small spin-dependent Seebeck coefficient for conventional ferromagnets without using complicated parameters.

Shrink-film configurable multiscale wrinkles for functional alignment of human embryonic stem cells and their cardiac derivatives.

PubMed

Chen, Aaron; Lieu, Deborah K; Freschauf, Lauren; Lew, Valerie; Sharma, Himanshu; Wang, Jiaxian; Nguyen, Diep; Karakikes, Ioannis; Hajjar, Roger J; Gopinathan, Ajay; Botvinick, Elliot; Fowlkes, Charless C; Li, Ronald A; Khine, Michelle

2011-12-22

A biomimetic substrate for cell-culture is fabricated by plasma treatment of a prestressed thermoplastic shrink film to create tunable multiscaled alignment "wrinkles". Using this substrate, the functional alignment of human embryonic stem cell derived cardiomyocytes is demonstrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Macroscopic Magnetization Control by Symmetry Breaking of Photoinduced Spin Reorientation with Intense Terahertz Magnetic Near Field

NASA Astrophysics Data System (ADS)

Kurihara, Takayuki; Watanabe, Hiroshi; Nakajima, Makoto; Karube, Shutaro; Oto, Kenichi; Otani, YoshiChika; Suemoto, Tohru

2018-03-01

We exploit an intense terahertz magnetic near field combined with femtosecond laser excitation to break the symmetry of photoinduced spin reorientation paths in ErFeO3 . We succeed in aligning macroscopic magnetization reaching up to 80% of total magnetization in the sample to selectable orientations by adjusting the time delay between terahertz and optical pump pulses. The spin dynamics are well reproduced by equations of motion, including time-dependent magnetic potential. We show that the direction of the generated magnetization is determined by the transient direction of spin tilting and the magnetic field at the moment of photoexcitation.

Observation of spin-polarized electron transport in Alq3 by using a low work function metal

NASA Astrophysics Data System (ADS)

Jang, Hyuk-Jae; Pernstich, Kurt P.; Gundlach, David J.; Jurchescu, Oana D.; Richter, Curt. A.

2012-09-01

We present the observation of magnetoresistance in Co/Ca/Alq3/Ca/NiFe spin-valve devices. Thin Ca layers contacting 150 nm thick Alq3 enable the injection of spin-polarized electrons into Alq3 due to the engineering of the band alignment. The devices exhibit symmetric current-voltage (I-V) characteristics indicating identical metal contacts on Alq3, and up to 4% of positive magnetoresistance was observed at 4.5 K. In contrast, simultaneously fabricated Co/Alq3/NiFe devices displayed asymmetric I-V curves due to the different metal electrodes, and spin-valve effects were not observed.

Structure of the first order reduced density matrix in three electron systems: A generalized Pauli constraints assisted study.

PubMed

Theophilou, Iris; Lathiotakis, Nektarios N; Helbig, Nicole

2018-03-21

We investigate the structure of the one-body reduced density matrix of three electron systems, i.e., doublet and quadruplet spin configurations, corresponding to the smallest interacting system with an open-shell ground state. To this end, we use configuration interaction (CI) expansions of the exact wave function in Slater determinants built from natural orbitals in a finite dimensional Hilbert space. With the exception of maximally polarized systems, the natural orbitals of spin eigenstates are generally spin dependent, i.e., the spatial parts of the up and down natural orbitals form two different sets. A measure to quantify this spin dependence is introduced and it is shown that it varies by several orders of magnitude depending on the system. We also study the ordering issue of the spin-dependent occupation numbers which has practical implications in reduced density matrix functional theory minimization schemes, when generalized Pauli constraints (GPCs) are imposed and in the form of the CI expansion in terms of the natural orbitals. Finally, we discuss the aforementioned CI expansion when there are GPCs that are almost "pinned."

Spin transport in carbon nanotubes bundles: An ab-initio study

NASA Astrophysics Data System (ADS)

Meena, Shweta; Choudhary, Sudhanshu

2017-10-01

First principles investigations are performed on understanding the spin-polarized transport in carbon nanotubes and carbon nanotube bundles consisting of (8 , 0) and (17 , 0) SWCNTs kept in vertical (out-of-plane) arrangement and contacted by two CrO2 Half-Metallic-Ferromagnetic (HMF) electrodes. On comparison of the results for all the structures, it is observed that carbon nanotube bundle consisting of (17 , 0) CNT offers high TMR ∼100% and the transport phenomenon is tunneling, since there are no transmission states near Fermi level. However, in individual (8 , 0) and (17 , 0) CNT the transport is not because of tunneling, since there are significant number of transmission states near Fermi level. High Magneto Resistance (MR) 96% and 99% is observed in individual (8 , 0) and (17 , 0) CNTs respectively. Both TMR and Spin Injection Efficiency η (Spin-Filtration) are higher in (17 , 0) carbon nanotube bundle structure, which is due to carbon nanotube bundle acting as a perfect barrier in vertical (out-of-plane) arrangement resulting in negligible spin-down current (I↓) in both Parallel Configuration (PC) and Antiparallel Configuration (APC).

Excitation energies of particle-hole states in {sup 208}Pb and the surface delta interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heusler, A., E-mail: A.Heusler@mpi-hd.mpg.de; Jolos, R. V., E-mail: Jolos@theor.jinr.ru; Brentano, P. von, E-mail: Brentano@ikp.uni-koeln.de

2013-07-15

The schematic shell model without residual interaction (SSM) assumes the same excitation energy for all spins in each particle-hole configuration multiplet. In {sup 208}Pb, more than forty states are known to contain almost the full strength of a single particle-hole configuration. The experimental excitation energy for a state with a certain spin differs from the energy predicted by the SSM by -0.2 to +0.6 MeV. The multiplet splitting is calculated with the surface delta interaction; it corresponds to the diagonal matrix element of the residual interaction in the SSM. For states containing more than 90% strength of a certain configurationmore » and for the centroid of several completely observed configurations, the calculated multiplet splitting often approximates the experimental excitation energy within 30 keV. The strong mixing within some pairs of states containing the full strengths of two configurations is explained.« less

Magnon detection using a ferroic collinear multilayer spin valve.

PubMed

Cramer, Joel; Fuhrmann, Felix; Ritzmann, Ulrike; Gall, Vanessa; Niizeki, Tomohiko; Ramos, Rafael; Qiu, Zhiyong; Hou, Dazhi; Kikkawa, Takashi; Sinova, Jairo; Nowak, Ulrich; Saitoh, Eiji; Kläui, Mathias

2018-03-14

Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y 3 Fe 5 O 12 |CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y 3 Fe 5 O 12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.

Competition between dynamic and structural disorder in a doped triangular antiferromagnet RbFe(MoO4)2

NASA Astrophysics Data System (ADS)

Smirnov, A. I.; Soldatov, T. A.; Petrenko, O. A.; Takata, A.; Kida, T.; Hagiwara, M.; Zhitomirsky, M. E.; Shapiro, A. Ya

2018-03-01

Magnetisation measurements and electron spin resonance (ESR) spectra of a doped quasi two dimensional (2D) antiferromagnet on a triangular lattice Rb1 ‑ x K x Fe(MoO4)2 reveal a crucial change of the ground state spin configuration and a disappearance of a characteristic 1/3-magnetisation plateau at x = 0.15. According to theory for triangular antiferromagnets with a weak random modulation of the exchange bonds, this is a result of the competition between the structural and dynamic disorders. The dynamic zero-point or thermal fluctuations are known to lift the degeneracy of the mean field ground state of a triangular antiferromagnet and cause the spin configuration to be the most collinear, while the static disorder provides another selection of the ground state, with the least collinear structure. Low-level doping (x ≤ 0.15) was found to decrease the Néel temperature and saturation field by only few percent, while the magnetisation plateau disappears completely and the spin configuration is drastically changed. ESR spectra confirm an impurity-induced change of the so-called Y-type structure to an inverted Y-structure for x = 0.15. For x = 0.075 the intermediate regime with the decrease of width and weakening of flattening of 1/3-plateau was found.

X-ray absorption and magnetic circular dichroism of LaCoO3 , La0.7Ce0.3CoO3 , and La0.7Sr0.3CoO3 films: Evidence for cobalt-valence-dependent magnetism

NASA Astrophysics Data System (ADS)

Merz, M.; Nagel, P.; Pinta, C.; Samartsev, A.; v. Löhneysen, H.; Wissinger, M.; Uebe, S.; Assmann, A.; Fuchs, D.; Schuppler, S.

2010-11-01

Epitaxial thin films of undoped LaCoO3 , of electron-doped La0.7Ce0.3CoO3 , and of hole-doped La0.7Sr0.3CoO3 exhibit ferromagnetic order with a transition temperature TC≈84K , 23 K, and 194 K, respectively. The spin-state structure for these compounds was studied by soft x-ray magnetic circular dichroism and by near-edge x-ray absorption fine structure at the CoL2,3 and OK edges. It turns out that superexchange between Co3+ high-spin and Co3+ low-spin states is responsible for the ferromagnetism in LaCoO3 . For La0.7Ce0.3CoO3 the Co3+ ions are in a low-spin state and the spin and orbital moments are predominantly determined by a Co2+ high-spin configuration. A spin blockade naturally explains the low transition temperature and the insulating characteristics of La0.7Ce0.3CoO3 . For La0.7Sr0.3CoO3 , on the other hand, the magnetic moments in the epitaxial films originate from high-spin Co3+ and high-spin Co4+ states. Ferromagnetism is induced by t2g double exchange between the two high-spin configurations. For all systems, a strong magnetic anisotropy is observed, with the magnetic moments essentially oriented within the film plane.

Quantum spin dynamics with pairwise-tunable, long-range interactions

PubMed Central

Hung, C.-L.; González-Tudela, Alejandro; Cirac, J. Ignacio; Kimble, H. J.

2016-01-01

We present a platform for the simulation of quantum magnetism with full control of interactions between pairs of spins at arbitrary distances in 1D and 2D lattices. In our scheme, two internal atomic states represent a pseudospin for atoms trapped within a photonic crystal waveguide (PCW). With the atomic transition frequency aligned inside a band gap of the PCW, virtual photons mediate coherent spin–spin interactions between lattice sites. To obtain full control of interaction coefficients at arbitrary atom–atom separations, ground-state energy shifts are introduced as a function of distance across the PCW. In conjunction with auxiliary pump fields, spin-exchange versus atom–atom separation can be engineered with arbitrary magnitude and phase, and arranged to introduce nontrivial Berry phases in the spin lattice, thus opening new avenues for realizing topological spin models. We illustrate the broad applicability of our scheme by explicit construction for several well-known spin models. PMID:27496329

Ultracold collisions between spin-orbit-coupled dipoles: General formalism and universality

NASA Astrophysics Data System (ADS)

Wang, Jia; Hougaard, Christiaan R.; Mulkerin, Brendan C.; Liu, Xia-Ji

2018-04-01

A theoretical study of the low-energy scattering properties of two aligned identical bosonic and fermionic dipoles in the presence of isotropic spin-orbit coupling is presented. A general treatment of particles with arbitrary (pseudo)spin is given in the framework of multichannel scattering. At ultracold temperatures and away from shape resonances or closed-channel dominated resonances, the cross section can be well described within the Born approximation to within corrections due to the s -wave scattering. We compare our findings with numerical calculations and find excellent agreement.

Toroidal high-spin isomers in the nucleus 304120

NASA Astrophysics Data System (ADS)

Staszczak, A.; Wong, Cheuk-Yin; Kosior, A.

2017-05-01

Background: Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis with I =Iz . The toroidal high-K isomeric states at their local energy minima can be theoretically predicted using the cranked self-consistent Skyrme-Hartree-Fock method. Purpose: We use the cranked Skyrme-Hartree-Fock method to predict the properties of the toroidal high-spin isomers in the superheavy nucleus 120304184. Method: Our method consists of three steps: First, we use the deformation-constrained Skyrme-Hartree-Fock-Bogoliubov approach to search for the nuclear density distributions with toroidal shapes. Next, using these toroidal distributions as starting configurations, we apply an additional cranking constraint of a large angular momentum I =Iz about the symmetry z axis and search for the energy minima of the system as a function of the deformation. In the last step, if a local energy minimum with I =Iz is found, we perform at this point the cranked symmetry- and deformation-unconstrained Skyrme-Hartree-Fock calculations to locate a stable toroidal high-spin isomeric state in free convergence. Results: We have theoretically located two toroidal high-spin isomeric states of 120304184 with an angular momentum I =Iz=81 ℏ (proton 2p-2h, neutron 4p-4h excitation) and I =Iz=208 ℏ (proton 5p-5h, neutron 8p-8h) at the quadrupole moment deformations Q20=-297.7 b and Q20=-300.8 b with energies 79.2 and 101.6 MeV above the spherical ground state, respectively. The nuclear density distributions of the toroidal high-spin isomers 120304184(Iz=81 ℏ and 208 ℏ ) have the maximum density close to the nuclear matter density, 0.16 fm-3, and a torus major to minor radius aspect ratio R /d =3.25 . Conclusions: We demonstrate that aligned angular momenta of Iz=81 ℏ and 208 ℏ arising from multiparticle-multihole excitations in the toroidal system of 120304184 can lead to high-spin isomeric states, even though the toroidal shape of 120304184 without spin is unstable. Toroidal energy minima without spin may be possible for superheavy nuclei with higher atomic numbers, Z ≳122 , as reported previously [7 A. Staszczak and C. Y. Wong, Acta Phys. Pol. B 40, 753 (2008)].

Toroidal high-spin isomers in the nucleus 120 304

DOE PAGES

Staszczak, A.; Wong, Cheuk-Yin; Kosior, A.

2017-05-22

Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis withmore » $$I=I_{z}$$. The toroidal high-$K$ isomeric states at their local energy minima can be theoretically predicted using the cranked self-consistent Skyrme-Hartree-Fock method. We use the cranked Skyrme-Hartree-Fock method to predict the properties of the toroidal high-spin isomers in the superheavy nucleus $$^{304}{120}_{184}$$. This method consists of three steps: first, we use the deformation-constrained Skyrme-Hartree-Fock-Bogoliubov approach to search for the nuclear density distributions with toroidal shapes. Next, using these toroidal distributions as starting configurations we apply an additional cranking constraint of a large angular momentum $$I=I_{z}$$ about the symmetry $z$-axis and search for the energy minima of the system as a function of the deformation. In the last step, if a local energy minimum with $$I=I_{z}$$ is found, we perform at this point the cranked symmetry- and deformation-unconstrained Skyrme-Hartree-Fock calculations to locate a stable toroidal high-spin isomeric state in free convergence. Furthemore, we have theoretically located two toroidal high-spin isomeric states of $$^{304}{120}_{184}$$ with an angular momentum $I$=$$I_z$$=81$$\\hbar$$ (proton 2p-2h, neutron 4p-4h excitation) and $I$=$$I_z$$=208$$\\hbar$$ (proton 5p-5h, neutron 8p-8h) at the quadrupole moment deformations $$Q_{20}=-297.7$$~b and $$Q_{20}=-300.8$$~b with energies 79.2 MeV and 101.6 MeV above the spherical ground state, respectively. The nuclear density distributions of the toroidal high-spin isomers $$^{304}{120}_{184}(I_z$$=81$$\\hbar$$ and 208$$\\hbar$$) have the maximum density close to the nuclear matter density, 0.16 fm$$^{-3}$$, and a torus major to minor radius aspect ratio $R/d=3.25$. Here, we demonstrate that aligned angular momenta of $$I_z$$=81$$\\hbar$$ and 208$$\\hbar$$ arising from multi-particle-multi-hole excitations in the toroidal system of $$^{304}{120}_{184}$$ can lead to high-spin isomeric states, even though the toroidal shape of $$^{304}120_{184}$$ without spin is unstable. Toroidal energy minima without spin may be possible for superheavy nuclei with higher atomic numbers, $$Z\\gtrsim$$122, as reported previously [A. Staszczak and C. Y. Wong,Acta Phys. Pol. B 40 , 753 (2008)].« less

Detection of pure inverse spin-Hall effect induced by spin pumping at various excitation

NASA Astrophysics Data System (ADS)

Inoue, H. Y.; Harii, K.; Ando, K.; Sasage, K.; Saitoh, E.

2007-10-01

Electric-field generation due to the inverse spin-Hall effect (ISHE) driven by spin pumping was detected and separated experimentally from the extrinsic magnetogalvanic effects in a Ni81Fe19/Pt film. By applying a sample-cavity configuration in which the extrinsic effects are suppressed, the spin pumping using ferromagnetic resonance gives rise to a symmetric spectral shape in the electromotive force spectrum, indicating that the motive force is due entirely to ISHE. This method allows the quantitative analysis of the ISHE and the spin-pumping effect. The microwave-power dependence of the ISHE amplitude is consistent with the prediction of a direct current-spin-pumping scenario.

Origin of the Energy Barrier to Chemical Reactions of O2 on Al(111): Evidence for Charge Transfer, Not Spin Selection

DTIC Science & Technology

2012-11-08

change of O2 spin, at the barrier [Fig. 3]; i.e., the corresponding diabatic surfaces cross. Far from the Al surface, the triplet state is...previous theoretical models, in particular nonadiabatic [17] or diabatic [16] approaches, which also find an energy barrier consistent with experiment...crossings of different diabatic O2 spin configuration sur- faces are accommodated by small spin fluctuations within the metal surface. For parallel

Development of a method of alignment between various SOLAR MAXIMUM MISSION experiments

NASA Technical Reports Server (NTRS)

1977-01-01

Results of an engineering study of the methods of alignment between various experiments for the solar maximum mission are described. The configuration studied consists of the instruments, mounts and instrument support platform located within the experiment module. Hardware design, fabrication methods and alignment techniques were studied with regard to optimizing the coalignment between the experiments and the fine sun sensor. The proposed hardware design was reviewed with regard to loads, stress, thermal distortion, alignment error budgets, fabrication techniques, alignment techniques and producibility. Methods of achieving comparable alignment accuracies on previous projects were also reviewed.

Hierarchical spin-orbital polarization of a giant Rashba system

PubMed Central

Bawden, Lewis; Riley, Jonathan M.; Kim, Choong H.; Sankar, Raman; Monkman, Eric J.; Shai, Daniel E.; Wei, Haofei I.; Lochocki, Edward B.; Wells, Justin W.; Meevasana, Worawat; Kim, Timur K.; Hoesch, Moritz; Ohtsubo, Yoshiyuki; Le Fèvre, Patrick; Fennie, Craig J.; Shen, Kyle M.; Chou, Fangcheng; King, Phil D. C.

2015-01-01

The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two “spin-split” branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector. PMID:26601268

Hierarchical spin-orbital polarization of a giant Rashba system.

PubMed

Bawden, Lewis; Riley, Jonathan M; Kim, Choong H; Sankar, Raman; Monkman, Eric J; Shai, Daniel E; Wei, Haofei I; Lochocki, Edward B; Wells, Justin W; Meevasana, Worawat; Kim, Timur K; Hoesch, Moritz; Ohtsubo, Yoshiyuki; Le Fèvre, Patrick; Fennie, Craig J; Shen, Kyle M; Chou, Fangcheng; King, Phil D C

2015-09-01

The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

Flight test of a spin parachute for use with a Super Arcas sounding rocket

NASA Technical Reports Server (NTRS)

Silbert, M. N.

1975-01-01

The development and flight testing of a specially configured 16.6 ft Disc Band Gap (DBG) Spin Parachute is discussed. The parachute is integrated with a modified Super Arcas launch vehicle. Total payload weight was 17.6 lbs including the Spin Parachute and a scientific payload, and lift-off weight was 100.3 lbs. The Super Arcas vehicle was despun from 18.4 cps. After payload separation at 244,170 ft the Spin Parachute and its payload attained a maximum spin rate of 2.4 cps. Total suspended weight of the Spin Parachute and its payload was 14.64 lbs.

An ontology-based semantic configuration approach to constructing Data as a Service for enterprises

NASA Astrophysics Data System (ADS)

Cai, Hongming; Xie, Cheng; Jiang, Lihong; Fang, Lu; Huang, Chenxi

2016-03-01

To align business strategies with IT systems, enterprises should rapidly implement new applications based on existing information with complex associations to adapt to the continually changing external business environment. Thus, Data as a Service (DaaS) has become an enabling technology for enterprise through information integration and the configuration of existing distributed enterprise systems and heterogonous data sources. However, business modelling, system configuration and model alignment face challenges at the design and execution stages. To provide a comprehensive solution to facilitate data-centric application design in a highly complex and large-scale situation, a configurable ontology-based service integrated platform (COSIP) is proposed to support business modelling, system configuration and execution management. First, a meta-resource model is constructed and used to describe and encapsulate information resources by way of multi-view business modelling. Then, based on ontologies, three semantic configuration patterns, namely composite resource configuration, business scene configuration and runtime environment configuration, are designed to systematically connect business goals with executable applications. Finally, a software architecture based on model-view-controller (MVC) is provided and used to assemble components for software implementation. The result of the case study demonstrates that the proposed approach provides a flexible method of implementing data-centric applications.

Solution to the sign problem in a frustrated quantum impurity model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hann, Connor T., E-mail: connor.hann@yale.edu; Huffman, Emilie; Chandrasekharan, Shailesh

2017-01-15

In this work we solve the sign problem of a frustrated quantum impurity model consisting of three quantum spin-half chains interacting through an anti-ferromagnetic Heisenberg interaction at one end. We first map the model into a repulsive Hubbard model of spin-half fermions hopping on three independent one dimensional chains that interact through a triangular hopping at one end. We then convert the fermion model into an inhomogeneous one dimensional model and express the partition function as a weighted sum over fermion worldline configurations. By imposing a pairing of fermion worldlines in half the space we show that all negative weightmore » configurations can be eliminated. This pairing naturally leads to the original frustrated quantum spin model at half filling and thus solves its sign problem.« less

Population Annealing Monte Carlo for Frustrated Systems

NASA Astrophysics Data System (ADS)

Amey, Christopher; Machta, Jonathan

Population annealing is a sequential Monte Carlo algorithm that efficiently simulates equilibrium systems with rough free energy landscapes such as spin glasses and glassy fluids. A large population of configurations is initially thermalized at high temperature and then cooled to low temperature according to an annealing schedule. The population is kept in thermal equilibrium at every annealing step via resampling configurations according to their Boltzmann weights. Population annealing is comparable to parallel tempering in terms of efficiency, but has several distinct and useful features. In this talk I will give an introduction to population annealing and present recent progress in understanding its equilibration properties and optimizing it for spin glasses. Results from large-scale population annealing simulations for the Ising spin glass in 3D and 4D will be presented. NSF Grant DMR-1507506.

Finite-temperature interatomic exchange and magnon softening in Fe overlayers on Ir(001)

NASA Astrophysics Data System (ADS)

Rodrigues, D. C. M.; Szilva, A.; Klautau, A. B.; Bergman, A.; Eriksson, O.; Etz, C.

2016-07-01

We evaluate how thermal effects soften the magnon dispersion in 6 layers of Fe(001) on top of Ir(001). We perform a systematic study considering noncollinear spin arrangement and calculate configuration-dependent exchange parameters Jij n c following the methodology described by Szilva et al. [Phys. Rev. Lett. 111, 127204 (2013)], 10.1103/PhysRevLett.111.127204. In addition, Monte Carlo simulations were performed in order to estimate the noncollinear spin arrangement as a function of temperature. Hence the Jij n c's related to these configurations were calculated and used in an atomistic spin dynamics approach to evaluate the magnon spectra. Our results show good agreement with recent room-temperature measurements, and highlights how thermal effects produce magnon softening in this, and similar, systems.

Compilation of Test Data on 111 Free-Spinning Airplane Models Tested in the Langley 15-Foot and 20-Foot Free-Spinning Tunnels

NASA Technical Reports Server (NTRS)

Malvestuto, Frank S.; Gale, Lawrence J.; Wood, John H.

1947-01-01

A compilation of free-spinning-airplane model data on the spin and recovery characteristics of 111 airplanes is presented. These data were previously published in separate memorandum reports and were obtained from free-spinning tests in the Langley 15-foot and the Langley 20-foot free-spinning tunnels. The model test data presented include the steady-spin and recovery characteristics of each model for various combinations of aileron and elevator deflections and for various loadings and dimensional configurations. Dimensional data, mass data, and a three-view drawing of the corresponding free-spinning tunnel model are also presented for each airplane. The data presented should be of value to designers and should facilitate the design of airplanes incorporating satisfactory spin-recovery characteristics.

Spin-tunnel investigation of the spinning characteristics of typical single-engine general aviation airplane designs. 2: Low-wing model A; tail parachute diameter and canopy distance for emergency spin recovery

NASA Technical Reports Server (NTRS)

Burk, S. M., Jr.; Bowman, J. S., Jr.; White, W. L.

1977-01-01

A spin tunnel study is reported on a scale model of a research airplane typical of low-wing, single-engine, light general aviation airplanes to determine the tail parachute diameter and canopy distance (riser length plus suspension-line length) required for energency spin recovery. Nine tail configurations were tested, resulting in a wide range of developed spin conditions, including steep spins and flat spins. The results indicate that the full-scale parachute diameter required for satisfactory recovery from the most critical conditions investigated is about 3.2 m and that the canopy distance, which was found to be critical for flat spins, should be between 4.6 and 6.1 m.

LABVIEW graphical user interface for precision multichannel alignment of Raman lidar at Jet Propulsion Laboratory, Table Mountain Facility.

PubMed

Aspey, R A; McDermid, I S; Leblanc, T; Howe, J W; Walsh, T D

2008-09-01

The Jet Propulsion Laboratory operates lidar systems at Table Mountain Facility (TMF), California (34.4 degrees N, 117.7 degrees W) and Mauna Loa Observatory, Hawaii (19.5 degrees N, 155.6 degrees W) under the framework of the Network for the Detection of Atmospheric Composition Change. To complement these systems a new Raman lidar has been developed at TMF with particular attention given to optimizing water vapor profile measurements up to the tropopause and lower stratosphere. The lidar has been designed for accuracies of 5% up to 12 km in the free troposphere and a detection capability of <5 ppmv. One important feature of the lidar is a precision alignment system using range resolved data from eight Licel transient recorders, allowing fully configurable alignment via a LABVIEW/C++ graphical user interface (GUI). This allows the lidar to be aligned on any channel while simultaneously displaying signals from other channels at configurable altitude/bin combinations. The general lidar instrumental setup and the details of the alignment control system, data acquisition, and GUI alignment software are described. Preliminary validation results using radiosonde and lidar intercomparisons are briefly presented.

The evolution from long-range magnetic order to spin-glass behaviour in PrAu2(Si1- xGex)2

NASA Astrophysics Data System (ADS)

Krimmel, A.; Hemberger, J.; Kegler, C.; Nicklas, M.; Engelmayer, A.; Knebel, G.; Fritsch, V.; Reehuis, M.; Brando, M.; Loidl, A.

1999-09-01

We have studied the magnetic behaviour of PrAu2(Si1-xGex)2 by means of magnetic susceptibility, resistivity, and heat capacity measurements, and x-ray and neutron powder diffraction. All compounds are isostructural and crystallize in the well known ThCr2Si2-type structure. PrAu2Si2 shows the characteristic features of a canonical spin glass with a freezing temperature of TF = 3 K. Completely unexpectedly, on introducing/increasing the atomic disorder by alloying with Ge, the spin-glass transition is suppressed as is first evident from a slight decrease of the freezing temperature TF up to x = 0.10. Long-range magnetic order sets in for xicons/Journals/Common/ge" ALT="ge" ALIGN="TOP"/>0.12. Within the range 0.15icons/Journals/Common/le" ALT="le" ALIGN="TOP"/> xicons/Journals/Common/le" ALT="le" ALIGN="TOP"/>1, all compounds show the same simple AF-I-type antiferromagnetic structure with a monotonic increase of both the Néel temperature and the ordered magnetic moment for increasing Ge concentration. The magnetic phase diagram of PrAu2(Si1-xGex)2 is explained by the presence of weak disorder at a constant level at the Au sites. Clear indications of crystal-field effects have been observed.

Stern-Gerlach dynamics with quantum propagators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Bailey C.; Berrondo, Manuel; Van Huele, Jean-Francois S.

2011-01-15

We study the quantum dynamics of a nonrelativistic neutral particle with spin in inhomogeneous external magnetic fields. We first consider fields with one-dimensional inhomogeneities, both unphysical and physical, and construct the corresponding analytic propagators. We then consider fields with two-dimensional inhomogeneities and develop an appropriate numerical propagation method. We propagate initial states exhibiting different degrees of space localization and various initial spin configurations, including both pure and mixed spin states. We study the evolution of their spin densities and identify characteristic features of spin density dynamics, such as the spatial separation of spin components, and spin localization or accumulation. Wemore » compare our approach and our results with the coverage of the Stern-Gerlach effect in the literature, and we focus on nonstandard Stern-Gerlach outcomes, such as radial separation, spin focusing, spin oscillation, and spin flipping.« less

Engineering electrocatalytic activity in nanosized perovskite cobaltite through surface spin-state transition

PubMed Central

Zhou, Shiming; Miao, Xianbing; Zhao, Xu; Ma, Chao; Qiu, Yuhao; Hu, Zhenpeng; Zhao, Jiyin; Shi, Lei; Zeng, Jie

2016-01-01

The activity of electrocatalysts exhibits a strongly dependence on their electronic structures. Specifically, for perovskite oxides, Shao-Horn and co-workers have reported a correlation between the oxygen evolution reaction activity and the eg orbital occupation of transition-metal ions, which provides guidelines for the design of highly active catalysts. Here we demonstrate a facile method to engineer the eg filling of perovskite cobaltite LaCoO3 for improving the oxygen evolution reaction activity. By reducing the particle size to ∼80 nm, the eg filling of cobalt ions is successfully increased from unity to near the optimal configuration of 1.2 expected by Shao-Horn's principle. Consequently, the activity is significantly enhanced, comparable to those of recently reported cobalt oxides with eg∼1.2 configurations. This enhancement is ascribed to the emergence of spin-state transition from low-spin to high-spin states for cobalt ions at the surface of the nanoparticles, leading to more active sites with increased reactivity. PMID:27187067

DOE Office of Scientific and Technical Information (OSTI.GOV)

Webb, Aaron P.; Carlson, Charles T.; Weaver, William T.

A mask alignment system for providing precise and repeatable alignment between ion implantation masks and workpieces. The system includes a mask frame having a plurality of ion implantation masks loosely connected thereto. The mask frame is provided with a plurality of frame alignment cavities, and each mask is provided with a plurality of mask alignment cavities. The system further includes a platen for holding workpieces. The platen may be provided with a plurality of mask alignment pins and frame alignment pins configured to engage the mask alignment cavities and frame alignment cavities, respectively. The mask frame can be lowered ontomore » the platen, with the frame alignment cavities moving into registration with the frame alignment pins to provide rough alignment between the masks and workpieces. The mask alignment cavities are then moved into registration with the mask alignment pins, thereby shifting each individual mask into precise alignment with a respective workpiece.« less

Turbine airfoil with dual wall formed from inner and outer layers separated by a compliant structure

DOEpatents

Campbell,; Christian X. , Morrison; Jay, A [Oviedo, FL

2011-12-20

A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a compliant structure. The compliant structure may be configured such that the outer layer may thermally expand without limitation by the inner layer. The compliant structure may be formed from a plurality of pedestals positioned generally parallel with each other. The pedestals may include a first foot attached to a first end of the pedestal and extending in a first direction aligned with the outer layer, and may include a second foot attached to a second end of the pedestal and extending in a second direction aligned with the inner layer.

Acoustic, Flow Related, and Performance Related Experimental Results for Generation 1.5 High Speed Civil Transport (HSCT) 2-Dimensional Exhaust Nozzles

NASA Technical Reports Server (NTRS)

Salikuddin, M.; Wisler, S.; Majjigi, R.

2004-01-01

The principle objectives of the current program were to experimentally investigate the repeatability of acoustic and aerodynamic characteristics of 2D-CD mixer-ejector nozzles and the effects on the acoustic and aerodynamic characteristics of 2D mixer-ejectors due to (1) the configurational variations, which include mixers with aligned CD chutes, aligned convergent chutes, and staggered CD chutes and aerodynamic cycle variables, (2) treatment variations by using different treatment materials, treating the ejector with varying area, location, and treatment thickness for a mixer-ejector configuration, and (3) secondary inlet shape (i.e., a more realistic inlet) and the blockage across the inlet (a possible fin-like structure needed for installation purpose) by modifying one of the inlet of a mixer-ejector configuration. The objectives also included the measurement dynamic pressures internal to the ejector for a few selected configuration to examine the internal noise characteristics.

MAGNETOHYDRODYNAMIC SIMULATION OF A DISK SUBJECTED TO LENSE-THIRRING PRECESSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorathia, Kareem A.; Krolik, Julian H.; Hawley, John F.

2013-11-01

When matter orbits around a central mass obliquely with respect to the mass's spin axis, the Lense-Thirring effect causes it to precess at a rate declining sharply with radius. Ever since the work of Bardeen and Petterson, it has been expected that when a fluid fills an orbiting disk, the orbital angular momentum at small radii should then align with the mass's spin. Nearly all previous work has studied this alignment under the assumption that a phenomenological 'viscosity' isotropically degrades fluid shears in accretion disks, even though it is now understood that internal stress in flat disks is due tomore » anisotropic MHD turbulence. In this paper we report a pair of matched simulations, one in MHD and one in pure (non-viscous) HD in order to clarify the specific mechanisms of alignment. As in the previous work, we find that disk warps induce radial flows that mix angular momentum of different orientation; however, we also show that the speeds of these flows are generically transonic and are only very weakly influenced by internal stresses other than pressure. In particular, MHD turbulence does not act in a manner consistent with an isotropic viscosity. When MHD effects are present, the disk aligns, first at small radii and then at large; alignment is only partial in the HD case. We identify the specific angular momentum transport mechanisms causing alignment and show how MHD effects permit them to operate more efficiently. Last, we relate the speed at which an alignment front propagates outward (in the MHD case) to the rate at which Lense-Thirring torques deliver angular momentum at smaller radii.« less

Angular-dependent EDMR linewidth for spin-dependent space charge limited conduction in a polycrystalline pentacene

NASA Astrophysics Data System (ADS)

Fukuda, Kunito; Asakawa, Naoki

2017-08-01

Spin-dependent space charge limited carrier conduction in a Schottky barrier diode using polycrystalline p-type π-conjugated molecular pentacene is explored using multiple-frequency electrically detected magnetic resonance (EDMR) spectroscopy with a variable-angle configuration. The measured EDMR spectra are decomposed into two components derived respectively from mobile and trapped positive polarons. The linewidth of the EDMR signal for the trapped polarons increases with increasing resonance magnetic field for an in-plane configuration where the normal vector of the device substrate is perpendicular to the resonance magnetic field, while it is independent of the field for an out-of-plane configuration. This difference is consistent with the pentacene arrangement on the device substrate, where pentacene molecules exhibit a uniaxial orientation on the out-of-substrate plane. By contrast, the mobile polarons do not show anisotropic behavior with respect to the resonance magnetic field, indicating that the anisotropic effect is averaged out owing to carrier motion. These results suggest that the orientational arrangements of polycrystalline pentacene molecules in a nano thin film play a crucial role in spin-dependent electrical conduction.

Slow dynamics in the geometrically frustrated magnet ZnFe2O4: Universal features of aging phenomena in spin glasses

NASA Astrophysics Data System (ADS)

Mamiya, H.; Tsujii, N.; Terada, N.; Nimori, S.; Kitazawa, H.; Hoshikawa, A.; Ishigaki, T.

2014-07-01

To clarify the universal features of spin glasses, we carefully studied slow dynamics in a geometrically frustrated magnet ZnFe2O4 with slight disorders, regarded as an "unconventional" Heisenberg spin glass, using time-resolved neutron diffractometry and magnetometry. The results indicate that "aging" can be attributed not to growth of the short-range order detected by a diffuse scattering but to aging of a hidden aperiodic correlation, as expected from theories for spin glasses. Concerning aging, peculiar behavior was found; the decay of thermoremanent magnetization is extremely accelerated if the sample is heated/cooled briefly midway through the isothermal slow relaxation. Conversely, magnetization surprisingly increases despite the absence of a magnetic field when the temperature returns after the brief heating/cooling. The behavior can be explained as a destabilization of the aged spin configuration due to the thermal perturbations and subsequent spontaneous restoration of the original spin configuration after the destabilization. Whereas such destabilization and restoration do not occur during freezing into numerous metastable states in a fixed energy landscape, these are possible in an energy landscape with a temperature-sensitive funnel-like structure. These features, consistent with the ghost domain scenario of the droplet picture, are the same as for conventional Heisenberg spin glasses such as dilute magnetic alloys and dilute magnetic semiconductors. In other words, they are universal features in Heisenberg spin glasses including unconventional ones.

Spin Evolution of Stellar Progenitors in Compact Binaries

NASA Astrophysics Data System (ADS)

Steinle, Nathan; Kesden, Michael

2018-01-01

Understanding the effects of various processes on the spins of stellar progenitors in compact binary systems is important for modeling the binary’s evolution and thus for interpreting the gravitational radiation emitted during inspiral and merger. Tides, winds, and natal kicks can drastically modify the binary parameters: tidal interactions increase the spin magnitudes, align the spins with the orbital angular momentum, and circularize the orbit; stellar winds decrease the spin magnitudes and cause mass loss; and natal kicks can misalign the spins and orbital angular momentum or even disrupt the binary. Also, during Roche lobe overflow, the binary may experience either stable mass transfer or common envelope evolution. The former can lead to a mass ratio reversal and alter the component spins, while the latter can dramatically shrink the binary separation. For a wide range of physically reasonable stellar-evolution scenarios, we compare the timescales of these processes to assess their relative contributions in determining the initial spins of compact binary systems.

Registration algorithm research for three dimensional medical image

NASA Astrophysics Data System (ADS)

Zhao, Jianping; Yang, Huamin; Ding, Ying

2008-03-01

The development of CT and MRI etc. technique offers the means by which we can research directly human internal structure. In clinic, usually various imaging results of a patient are combined for analysis. At present, in the most case, doctors make a diagnosis by observing some slice images of human body. As complexity and configuration diversity of the structure of human body organ, and as well unpredictiveness of focus location and configuration, it is difficult to imagine the cubic configuration of organs and their relationship from these 2D slices without corresponding specialty knowledge and practical experience. So it isn't satisfied with preferable requests of medical diagnosis that only aligning two 2D images to get one 2D slice image. As a result we need extend registration t problem to 3D image. As the quantity of 3D volume data are much more, it undoubtedly increases calculation quantity for aligning two 3D images accurately. It forces us to find some good methods that can achieve better effect on precision and satisfy the demand for time. So in this paper digitally reconstructed radiograph (DRR) image method is proposed to solve correlative problems. Ray tracking two 3D images and digitally reconstruct to create two 2D images, by aligning 2D data to realize to align 3D data.

Results of recent NASA studies on automatic spin prevention for fighter aircraft

NASA Technical Reports Server (NTRS)

Chambers, J. R.; Nguyen, L. T.

1976-01-01

A broad based research program was developed to eliminate or minimize inadvertent spins for advanced military aircraft. Recent piloted simulator studies and airplane flight tests have demonstrated that the automatic control systems in use on current fighters can be tailored to provide a high degree of spin resistance for some configurations without restrictions to maneuverability. Such systems result in greatly increased tactical effectiveness, safety, and pilot confidence.

Spinning top urethra and lower urinary tract dysfunction in a young female.

PubMed

Dogra, P N; Ansari, M S

2004-06-07

Spinning top urethra (STU) denotes a particular urethral configuration that is a dilated posterior urethra mainly seen in young girls or women. STU deformity arises secondary to detrusor instability, leading to a rise the intravesical pressure against a closed sphincter. We describe a case of spinning top urethra in a 30-year-old woman who presented with lower urinary tract symptoms and left flank pain.

Spinning Top Urethra and Lower Urinary Tract Dysfunction in a Young Female

PubMed Central

Dogra, P.N.; Ansari, M.S.

2004-01-01

Spinning top urethra (STU) denotes a particular urethral configuration that is a dilated posterior urethra mainly seen in young girls or women. STU deformity arises secondary to detrusor instability, leading to a rise the intravesical pressure against a closed sphincter. We describe a case of spinning top urethra in a 30-year-old woman who presented with lower urinary tract symptoms and left flank pain. PMID:15349536

Spin coherent states phenomena probed by quantum state tomography in Zeeman perturbed nuclear quadrupole resonance

NASA Astrophysics Data System (ADS)

Teles, João; Auccaise, Ruben; Rivera-Ascona, Christian; Araujo-Ferreira, Arthur G.; Andreeta, José P.; Bonagamba, Tito J.

2018-07-01

Recently, we reported an experimental implementation of quantum information processing (QIP) by nuclear quadrupole resonance (NQR). In this work, we present the first quantum state tomography (QST) experimental implementation in the NQR QIP context. Two approaches are proposed, employing coherence selection by temporal and spatial averaging. Conditions for reduction in the number of cycling steps are analyzed, which can be helpful for larger spin systems. The QST method was applied to the study of spin coherent states, where the alignment-to-orientation phenomenon and the evolution of squeezed spin states show the effect of the nonlinear quadrupole interaction intrinsic to the NQR system. The quantum operations were implemented using a single-crystal sample of KClO3 and observing ^{35}Cl nuclei, which posses spin 3/2.

Intrinsic Local Distortions and charge carrier behavior in CMR manganites and cobaltites

NASA Astrophysics Data System (ADS)

Bridges, Frank

2010-03-01

We compare and contrast the local structure and electronic configurations in two oxide systems La1-xSrxCoO3 (LSCO) and La1-yCayMnO3 (LCMO). Although these oxides may appear quite similar they have rather different properties. At x=0, LaCoO3 (LCO) has unusual magnetic properties - diamagnetic at low T but developing a moment near 100K. The Sr doped LSCO materials show ferromagnetism for x > 0.2. For LCO, one of the possible spin state configurations called the intermediate spin (IS) state (S=1), should be Jahn-Teller (JT) active, while the low spin (S=0) and high spin (S=2) states have no JT distortion. Early local structure measurements suggested a JT distortion was present in LCO and therefore supported an IS spin model. However we find no evidence for any significant JT distortion (and hence no support for the IS model) for a range of bulk and nanoparticle cobaltites La1-xSrxCoO3, x = 0 - 0.35. In contrast there are large JT distortions in the manganites LCMO, 0.2 < x < 0.5 (Mn-O bonds), for which CMR behavior is observed. We have shown that the JT distortions in the manganites depend on both temperature T and magnetic field B, and from the B-field dependence, propose the size and nature of the polarons in LCMO. We also present Co K-edge XANES data that shown no significant shift of the edge for the cobaltites as the Sr concentration increases from x =0 to 0.35 indicating essentially no change in the electronic configuration about Co; consequently, the holes introduced via Sr doping appear to go primarily into the O bands. In contrast there is a large shift of the Mn K-edge with Ca doping indicating a change in the average Mn valence, and a corresponding change in the Mn electronic configuration. We briefly discuss some possible models.

Geometrical dependence of spin current absorption into a ferromagnetic nanodot

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nomura, Tatsuya; Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp

We have investigated the absorption property of the diffusive pure spin current due to a ferromagnetic nanodot in a laterally configured ferromagnetic/nonmagnetic hybrid nanostructure. The spin absorption in a nano-pillar-based lateral-spin-valve structure was confirmed to increase with increasing the lateral dimension of the ferromagnetic dot. However, the absorption efficiency was smaller than that in a conventional lateral spin valve based on nanowire junctions because the large effective cross section of the two dimensional nonmagnetic film reduces the spin absorption selectivity. We also found that the absorption efficiency of the spin current is significantly enhanced by using a thick ferromagnetic nanodot.more » This can be understood by taking into account the spin absorption through the side surface of the ferromagnetic dot quantitatively.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Qiang; Zhou, Liping, E-mail: zhoulp@suda.edu.cn; Cheng, Jue-Fei

Electronic structures and coherent quantum transport properties are explored for spin-crossover molecule iron-benzene Fe(Bz){sub 2} using density functional theory combined with non-equilibrium Green’s function. High- and low-spin states are investigated for two different lead-molecule junctions. It is found that the asymmetrical T-shaped contact junction in the high-spin state behaves as an efficient spin filter while it has a smaller conductivity than that in the low-spin state. Large spin Seebeck effect is also observed in asymmetrical T-shaped junction. Spin-polarized properties are absent in the symmetrical H-shaped junction. These findings strongly suggest that both the electronic and contact configurations play significant rolesmore » in molecular devices and metal-benzene complexes are promising materials for spintronics and thermo-spintronics.« less

Toroidal high-spin isomers in light nuclei with N ≠ Z

NASA Astrophysics Data System (ADS)

Staszczak, A.; Wong, Cheuk-Yin

2015-11-01

The combined considerations of both the bulk liquid-drop-type behavior and the quantized aligned rotation with cranked Skyrme-Hartree-Fock approach revealed previously (Staszczak and Wong 2014 Phys. Lett. B 738 401) that even-even, N = Z, toroidal high-spin isomeric states have general occurrences for light nuclei with 28≤slant A≤slant 52. We find that in this mass region there are in addition N\

Rotary balance data for a single-engine agricultural airplane configuration for an angle-of-attack range of 8 deg to 90 deg

NASA Technical Reports Server (NTRS)

Mulcay, W. J.; Chu, J.

1980-01-01

Aerodynamic characteristics obtained in a helical flow environment utilizing a rotary balance located in the Langley spin tunnel are presented in plotted form for a 1/10 scale single engine agricultural airplane model. The configurations tested include the basic airplane, various wing leading edge and wing tip devices, elevator, aileron, and rudder control settings, and other modifications. Data are presented without analysis for an angle of attack range of 8 deg to 90 deg, and clockwise and counter-clockwise rotations covering a spin coefficient range from 0 to .9.

Spin Seebeck effect in a metal-single-molecule-magnet-metal junction

NASA Astrophysics Data System (ADS)

Niu, Pengbin; Liu, Lixiang; Su, Xiaoqiang; Dong, Lijuan; Luo, Hong-Gang

2018-01-01

We investigate the nonlinear regime of temperature-driven spin-related currents through a single molecular magnet (SMM), which is connected with two metal electrodes. Under a large spin approximation, the SMM is simplified to a natural two-channel model possessing spin-opposite configuration and Coulomb interaction. We find that in temperature-driven case the system can generate spin-polarized currents. More interestingly, at electron-hole symmetry point, the competition of the two channels induces a temperature-driven pure spin current. This device demonstrates that temperature-driven SMM junction shows some results different from the usual quantum dot model, which may be useful in the future design of thermal-based molecular spintronic devices.

High-spin states in 103,105Mo, 103Nb, and the νh11/2 alignment

NASA Astrophysics Data System (ADS)

Hua, H.; Wu, C. Y.; Cline, D.; Hayes, A. B.; Teng, R.; Clark, R. M.; Fallon, P.; Macchiavelli, A. O.; Vetter, K.

2002-06-01

High-spin states in neutron-rich nuclei 103,105Mo,103Nb have been studied using the 238U(α,f) fusion-fission reaction. The deexcitation γ rays were detected by Gammasphere in coincidence with the detection of both fission fragments by the Rochester 4π heavy-ion detector array, CHICO. The measured fission kinematics were used to deduce the masses and velocity vectors for both fission fragments. This allowed Doppler-shift corrections to be applied to the observed γ rays on an event-by-event basis and the origin of γ rays from either fission fragment to be established. With such advantages, the yrast sequences for these nuclei have been extended to the band crossing region. This band crossing is ascribed to the alignment of a pair of h11/2 neutrons, which is supported by the observed blocking effect for the νh11/2 band in 105Mo while there is no evidence for blocking in the alignment measured for either the νd5/2 band in 103Mo or the πg9/2 band in 103Nb. The observed upbend, rather than the sharp backbend seen in the Ru-Pd region, indicates a strong interaction between the ground-state and the aligned h11/2 bands.

Superconducting spin valves controlled by spiral re-orientation in B20-family magnets

NASA Astrophysics Data System (ADS)

Pugach, N. G.; Safonchik, M.; Champel, T.; Zhitomirsky, M. E.; Lähderanta, E.; Eschrig, M.; Lacroix, C.

2017-10-01

We propose a superconducting spin-triplet valve, which consists of a superconductor and an itinerant magnetic material, with the magnet showing an intrinsic non-collinear order characterized by a wave vector that may be aligned in a few equivalent preferred directions under the control of a weak external magnetic field. Re-orienting the spiral direction allows one to controllably modify long-range spin-triplet superconducting correlations, leading to spin-valve switching behavior. Our results indicate that the spin-valve effect may be noticeable. This bilayer may be used as a magnetic memory element for cryogenic nanoelectronics. It has the following advantages in comparison to superconducting spin valves proposed previously: (i) it contains only one magnetic layer, which may be more easily fabricated and controlled; (ii) its ground states are separated by a potential barrier, which solves the "half-select" problem of the addressed switch of memory elements.

Active control of magnetoresistance of organic spin valves using ferroelectricity

PubMed Central

Sun, Dali; Fang, Mei; Xu, Xiaoshan; Jiang, Lu; Guo, Hangwen; Wang, Yanmei; Yang, Wenting; Yin, Lifeng; Snijders, Paul C.; Ward, T. Z.; Gai, Zheng; Zhang, X.-G.; Lee, Ho Nyung; Shen, Jian

2014-01-01

Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, which is correlated with the polarization of the ferroelectric layer; the magnetoresistance even changes sign when the electric polarization of the ferroelectric layer is reversed. These findings enable active control of resistance using both electric and magnetic fields, opening up possibility for multi-state organic spin valves. PMID:25008155

The dynamics and optimal control of spinning spacecraft and movable telescoping appendages, part B: Effect of gravity-gradient torques on the dynamics of a spinning spacecraft with telescoping appendages

NASA Technical Reports Server (NTRS)

Bainum, P. M.; Rajan, M.

1977-01-01

The effects of gravity gradient torques during boom deployment maneuvers of a spinning spacecraft are examined. Configurations where the booms extended only along the hub principal axes and where one or two booms are offset from the principal axes were considered. For the special case of symmetric deployment (principal axes booms) the stability boundaries are determined, and a stability chart is used to study the system behavior. Possible cases of instability during this type of maneuver are identified. In the second configuration an expression for gravity torque about the hub center of mass was developed. The nonlinear equations of motion are solved numerically, and the substantial influence of the gravity torque during asymmetric deployment maneuvers is indicated.

Nanostructured complex oxides as a route towards thermal behavior in artificial spin ice systems

NASA Astrophysics Data System (ADS)

Chopdekar, R. V.; Li, B.; Wynn, T. A.; Lee, M. S.; Jia, Y.; Liu, Z. Q.; Biegalski, M. D.; Retterer, S. T.; Young, A. T.; Scholl, A.; Takamura, Y.

2017-07-01

We have used soft x-ray photoemission electron microscopy to image the magnetization of single-domain L a0.7S r0.3Mn O3 nanoislands arranged in geometrically frustrated configurations such as square ice and kagome ice geometries. Upon thermal randomization, ensembles of nanoislands with strong interisland magnetic coupling relax towards low-energy configurations. Statistical analysis shows that the likelihood of ensembles falling into low-energy configurations depends strongly on the annealing temperature. Annealing to just below the Curie temperature of the ferromagnetic film (TC=338 K ) allows for a much greater probability of achieving low-energy configurations as compared to annealing above the Curie temperature. At this thermally active temperature of 325 K, the ensemble of ferromagnetic nanoislands explore their energy landscape over time and eventually transition to lower energy states as compared to the frozen-in configurations obtained upon cooling from above the Curie temperature. Thus, this materials system allows for a facile method to systematically study thermal evolution of artificial spin ice arrays of nanoislands at temperatures modestly above room temperature.

Snakes, rotators, serpents and the octahedral group

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fieguth, T.

1986-04-01

Specific configurations of horizontal and vertical bending magnets are given that, when acting on the spin polarization vector of a particle beam, generate a group of 24 operators isomorphic to the group of rotational symmetries of a cube, known as the octahedral group. Some of these configurations have the feature of converting transversely polarized beams to longitudinally polarized beams (or vice versa) at the midpoint of the configuration for, in principle, all beam energies. Since the first order optical transfer matrix for each half of these configurations is nearly that of a drift region, the external geometry remains unchanged andmore » midpoint dispersion is not introduced. Changing field strengths and/or polarities allows a configuration to serve as either a Snake(1/sup st/ or 2/sup nd/ kind) or a Rotator, where in both cases the spin polarization is longitudinal at the midpoint. In this conceptualization, emphasis has been placed on electron beams and, indeed, for these beams some practical applications can be envisioned. However, due to the relatively high integrated field strengths required, application of these concepts to proton beams may be more promising.« less

Configuration maintaining control of three-body ring tethered system based on thrust compensation

NASA Astrophysics Data System (ADS)

Huang, Panfeng; Liu, Binbin; Zhang, Fan

2016-06-01

Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

Computational design and engineering of polymeric orthodontic aligners.

PubMed

Barone, S; Paoli, A; Razionale, A V; Savignano, R

2016-10-05

Transparent and removable aligners represent an effective solution to correct various orthodontic malocclusions through minimally invasive procedures. An aligner-based treatment requires patients to sequentially wear dentition-mating shells obtained by thermoforming polymeric disks on reference dental models. An aligner is shaped introducing a geometrical mismatch with respect to the actual tooth positions to induce a loading system, which moves the target teeth toward the correct positions. The common practice is based on selecting the aligner features (material, thickness, and auxiliary elements) by only considering clinician's subjective assessments. In this article, a computational design and engineering methodology has been developed to reconstruct anatomical tissues, to model parametric aligner shapes, to simulate orthodontic movements, and to enhance the aligner design. The proposed approach integrates computer-aided technologies, from tomographic imaging to optical scanning, from parametric modeling to finite element analyses, within a 3-dimensional digital framework. The anatomical modeling provides anatomies, including teeth (roots and crowns), jaw bones, and periodontal ligaments, which are the references for the down streaming parametric aligner shaping. The biomechanical interactions between anatomical models and aligner geometries are virtually reproduced using a finite element analysis software. The methodology allows numerical simulations of patient-specific conditions and the comparative analyses of different aligner configurations. In this article, the digital framework has been used to study the influence of various auxiliary elements on the loading system delivered to a maxillary and a mandibular central incisor during an orthodontic tipping movement. Numerical simulations have shown a high dependency of the orthodontic tooth movement on the auxiliary element configuration, which should then be accurately selected to maximize the aligner's effectiveness. Copyright © 2016 John Wiley & Sons, Ltd.

Charge instability in double quantum dots in Ge/Si core/shell nanowires

NASA Astrophysics Data System (ADS)

Zarassi, Azarin; Su, Zhaoen; Schwenderling, Jens; Frolov, Sergey M.; Hocevar, Moïra; Nguyen, Binh-Minh; Yoo, Jinkyoung; Dayeh, Shadi A.

Controlling dephasing times are of great challenge in the studies of spin qubit. Reported long spin coherence time and predicted strong spin-orbit interaction of holes in Ge/Si core/shell nanowires, as well as their weak coupling to very few nuclear spins of these group IV semiconductors, persuade electrical spin control. We have established Pauli spin blockade in gate-tunable quantum dots formed in these nanowires. The g-factor has been measured and evidence of spin-orbit interaction has been observed in the presence of magnetic field. However, electrical control of spins requires considerable stability in the double dot configuration, and imperfectly these dots suffer from poor stability. We report on fabrication modifications on Ge/Si core/shell nanowires, as well as measurement techniques to suppress the charge instabilities and ease the way to study spin-orbit coupling and resolve electric dipole spin resonance.

Magnetic modulation of inverse spin Hall effect in lateral spin-valves

NASA Astrophysics Data System (ADS)

Andrianov, T.; Vedyaev, A.; Dieny, B.

2018-05-01

We analytically investigated the spin-dependent transport properties in a lateral spin-valve device comprising pinned ferromagnetic electrodes allowing the injection of a spin current in a spin conducting channel where spin orbit scattering takes place. This produces an inverse spin Hall (ISHE) voltage across the thickness of the spin conducting channel. It is shown that by adding an extra soft ferromagnetic electrode with rotatable magnetization along the spin conducting channel, the ISHE generated voltage can be magnetically modulated by changing the magnetization orientation of this additional electrode. The dependence of the ISHE voltage on the direction of magnetization of the ferromagnetic electrode with rotatable magnetization was calculated in various configurations. Our results suggest that such structures could be considered as magnetic field sensors in situations where the total thickness of the sensor is constrained such as in hard disk drive readers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai,M.; Ptitsyn, V.; Roser, T.

To keep the spin tune in the spin depolarizing resonance free region is required for accelerating polarized protons to high energy. In RHIC, two snakes are located at the opposite side of each accelerator. They are configured to yield a spin tune of 1/2. Two pairs of spin rotators are located at either side of two detectors in each ring in RHIC to provide longitudinal polarization for the experiments. Since the spin rotation from vertical to longitudinal is localized between the two rotators, the spin rotators do not change the spin tune. However, due to the imperfection of the orbitsmore » around the snakes and rotators, the spin tune can be shifted. This note presents the impact of the horizontal orbital angle between the two snakes on the spin tune, as well as the effect of the vertical orbital angle between two rotators at either side of the collision point on the spin tune.« less

Spin-dependent transport and current modulation in a current-in-plane spin-valve field-effect transistor

NASA Astrophysics Data System (ADS)

Kanaki, Toshiki; Koyama, Tomohiro; Chiba, Daichi; Ohya, Shinobu; Tanaka, Masaaki

2016-10-01

We propose a current-in-plane spin-valve field-effect transistor (CIP-SV-FET), which is composed of a ferromagnet/nonferromagnet/ferromagnet trilayer structure and a gate electrode. This is a promising device alternative to spin metal-oxide-semiconductor field-effect transistors. Here, we fabricate a ferromagnetic-semiconductor GaMnAs-based CIP-SV-FET and demonstrate its basic operation of the resistance modulation both by the magnetization configuration and by the gate electric field. Furthermore, we present the electric-field-assisted magnetization reversal in this device.

Investigations of modifications to improve the spin resistance of a high-wing, single-engine, light airplane

NASA Technical Reports Server (NTRS)

Manuel, G. S.; Dicarlo, D. J.; Stough, H. P., III; Brown, P. W.; Stuever, R. A.

1989-01-01

A general aviation aircraft with drooped leading edge modifications for improvement of lateral stability at high angles of attack has been flight tested in combination with a ventral fin which improves directional stability. The two modifications were assessed in light of spin-resistance criteria proposed for incorporation into FAA certification regulations. The configuration combining outboard wing leading-edge droop and a ventral fin yielded a substantial increase in spin resistance, but fell short of all requirements encompassed by the proposed spin-resistance criteria.

Preparation of CNTs rope by electrostatic and airflow field carding with high speed rotor spinning

NASA Astrophysics Data System (ADS)

Dai, J. F.; Liu, J. F.; Zou, J. T.; Dai, Y. L.

2015-12-01

The large-scale preparation of disorderly CNTs with a length larger than 3 mm using CVD method were aligned in polymer monomer airflow fields in a quartz tube with an internal diameter of 200 μm and a length of 1.5 m. The airflow aligned CNTs at the output end of the pipe connects to a copper nozzle with an electrostatic field of applied voltage 5x105 V/m and space length of 0.03 m, which were further realigned using via electrostatic spinning. End to end spray into the high speed rotor twisted single-stranded carbon nanotubes threads via rotor spinning technology. The essential component of this technique was the use of carbon nanotubes at a high rotory speed (200000 r/min) combined with the double twisting of filaments that were twisted together to increase the radial friction of the entire section. SEM micrography showed that carbon nanotube thread has a uniform diameter of approximately 200 μm. Its tensile strength was tested up to 2.7 Gpa, with a length of several meters.

Design, manufacture and spin test of high contact ratio helicopter transmission utilizing Self-Aligning Bearingless Planetary (SABP)

NASA Technical Reports Server (NTRS)

Folenta, Dezi; Lebo, William

1988-01-01

A 450 hp high ratio Self-Aligning Bearingless Planetary (SABP) for a helicopter application was designed, manufactured, and spin tested under NASA contract NAS3-24539. The objective of the program was to conduct research and development work on a high contact ratio helical gear SABP to reduce weight and noise and to improve efficiency. The results accomplished include the design, manufacturing, and no-load spin testing of two prototype helicopter transmissions, rated at 450 hp with an input speed of 35,000 rpm and an output speed of 350 rpm. The weight power density ratio of these gear units is 0.33 lb hp. The measured airborne noise at 35,000 rpm input speed and light load is 94 dB at 5 ft. The high speed, high contact ratio SABP transmission appears to be significantly lighter and quieter than comtemporary helicopter transmissions. The concept of the SABP is applicable not only to high ratio helicopter type transmissions but also to other rotorcraft and aircraft propulsion systems.

Stimulated Raman adiabatic passage preparation of a coherent superposition of ThO H3Δ1 states for an improved electron electric-dipole-moment measurement

NASA Astrophysics Data System (ADS)

Panda, C. D.; O'Leary, B. R.; West, A. D.; Baron, J.; Hess, P. W.; Hoffman, C.; Kirilov, E.; Overstreet, C. B.; West, E. P.; DeMille, D.; Doyle, J. M.; Gabrielse, G.

2016-05-01

Experimental searches for the electron electric-dipole moment (EDM) probe new physics beyond the standard model. The current best EDM limit was set by the ACME Collaboration [Science 343, 269 (2014), 10.1126/science.1248213], constraining time-reversal symmetry (T ) violating physics at the TeV energy scale. ACME used optical pumping to prepare a coherent superposition of ThO H3Δ1 states that have aligned electron spins. Spin precession due to the molecule's internal electric field was measured to extract the EDM. We report here on an improved method for preparing this spin-aligned state of the electron by using stimulated Raman adiabatic passage (STIRAP). We demonstrate a transfer efficiency of 75 %±5 % , representing a significant gain in signal for a next-generation EDM experiment. We discuss the particularities of implementing STIRAP in systems such as ours, where molecular ensembles with large phase-space distributions are transferred via weak molecular transitions with limited laser power and limited optical access.

Correlation effect and magnetic moments in Cr2Te3

NASA Astrophysics Data System (ADS)

Youn, S. J.; Kwon, S. K.; Min, B. I.

2007-05-01

The electronic and magnetic structures of Cr2Te3 have been studied theoretically using the linearized muffin-tin orbitals band method. Experimental photoemission spectra and magnetic moments can be described better when the on-site Coulomb correlation U of Cr 3d electrons is considered using the local spin-density approximation+U method. The proper size of U is found to be U ˜1.7eV. The complex magnetic behaviors of Cr2Te3 come from the degeneracy of parallel and antiparallel alignments of CrI spin to CrII and CrIII spins.

A Ramsey’s Method With Pulsed Neutrons for a T-Violation Experiment

PubMed Central

Masuda, Y.; Ino, T.; Muto, S.; Skoy, V.

2005-01-01

A Ramsey’s method with pulsed neutrons is discussed for neutron spin manipulation in a time reversal (T) symmetry violation experiment. The neutron spin (sn) is aligned to the direction of a vector product of the nuclear spin (I) and the neutron momentum (kn) for the measurement of a T-odd correlation term, which is represented as sn · (kn × I), during propagation through a polarized nuclear target. The phase control and amplitude modulation of separated oscillatory fields are discussed for the measurement of the T-odd correlation term. PMID:27308171

A Ramsey's Method With Pulsed Neutrons for a T-Violation Experiment.

PubMed

Masuda, Y; Ino, T; Muto, S; Skoy, V

2005-01-01

A Ramsey's method with pulsed neutrons is discussed for neutron spin manipulation in a time reversal (T) symmetry violation experiment. The neutron spin (s n) is aligned to the direction of a vector product of the nuclear spin ( I ) and the neutron momentum ( k n) for the measurement of a T-odd correlation term, which is represented as s n · ( k n × I ), during propagation through a polarized nuclear target. The phase control and amplitude modulation of separated oscillatory fields are discussed for the measurement of the T-odd correlation term.

Spin alignment following inelastic scattering of 17Ne, lifetime of 16F, and its constraint on the continuum coupling strength

NASA Astrophysics Data System (ADS)

Charity, R. J.; Brown, K. W.; Okołowicz, J.; Płoszajczak, M.; Elson, J. M.; Reviol, W.; Sobotka, L. G.; Buhro, W. W.; Chajecki, Z.; Lynch, W. G.; Manfredi, J.; Shane, R.; Showalter, R. H.; Tsang, M. B.; Weisshaar, D.; Winkelbauer, J. R.; Bedoor, S.; Wuosmaa, A. H.

2018-05-01

The sequential two-proton decay of the second excited state in 17Ne, produced by inelastic excitation at intermediate energy, is studied. This state is found to be highly spin aligned, providing another example of a recently discovered alignment mechanism. The fortuitous condition that the second decay step is slightly more energetic than the first, permits the lifetime of the one-proton daughter, the ground state of 16F, to be determined from the magnitude of the final-state interactions between the protons. This new method gave a result [Γ =20.6 (57 ) keV] consistent with that obtained by directly measuring the width of the state [Γ =21.3 (51 ) keV]. This width allows one to determine the continuum coupling constant in this mass region. Real-energy continuum-shell-model studies yield a satisfactory description of both spectra and widths of low-energy resonances in 16F and suggest an unusual large ratio of proton-proton to proton-neutron continuum couplings in the vicinity of the proton drip line.

Thermodynamics of energy, charge, and spin currents in a thermoelectric quantum-dot spin valve

NASA Astrophysics Data System (ADS)

Tang, Gaomin; Thingna, Juzar; Wang, Jian

2018-04-01

We provide a thermodynamically consistent description of energy, charge, and spin transfers in a thermoelectric quantum-dot spin valve in the collinear configuration based on nonequilibrium Green's function and full counting statistics. We use the fluctuation theorem symmetry and the concept of entropy production to characterize the efficiency with which thermal gradients can transduce charges or spins against their chemical potentials, arbitrary far from equilibrium. Close to equilibrium, we recover the Onsager reciprocal relations and the connection to linear response notions of performance such as the figure of merit. We also identify regimes where work extraction is more efficient far then close from equilibrium.

Secure alignment of coordinate systems using quantum correlation

NASA Astrophysics Data System (ADS)

Rezazadeh, F.; Mani, A.; Karimipour, V.

2017-08-01

We show that two parties far apart can use shared entangled states and classical communication to align their coordinate systems with a very high fidelity. Moreover, compared with previous methods proposed for such a task, i.e., sending parallel or antiparallel pairs or groups of spin states, our method has the extra advantages of using single-qubit measurements and also being secure, so that third parties do not extract any information about the aligned coordinate system established between the two parties. The latter property is important in many other quantum information protocols in which measurements inevitably play a significant role.

On the Ionization and Ion Transmission Efficiencies of Different ESI-MS Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, Jonathan T.; Marginean, Ioan; Smith, Richard D.

2014-09-30

It is well known that the achievable sensitivity of electrospray ionization mass spectrometry (ESI-MS) is largely determined by the ionization efficiency in the ESI source and ion transmission efficiency through the ESI-MS interface. In this report we systematically study the ion transmission and ionization efficiencies in different ESI-MS interface configurations. The configurations under investigation include a single emitter/single inlet capillary, single emitter/multi-inlet capillary, and a subambient pressure ionization with nanoelectrospray (SPIN) MS interfaces with a single emitter and an emitter array, respectively. We present an effective method to evaluate the overall ion utilization efficiency of an ESI-MS interface by measuringmore » the total gas phase ion current transmitted through the interface and correlating it to the observed ion abundance measured in the corresponding mass spectrum. Our experimental results suggest that the overall ion utilization efficiency in the SPIN-MS interface configurations is better than that in the inlet capillary based ESI-MS interface configurations.« less

Strong confinement-induced engineering of the g factor and lifetime of conduction electron spins in Ge quantum wells

PubMed Central

Giorgioni, Anna; Paleari, Stefano; Cecchi, Stefano; Vitiello, Elisa; Grilli, Emanuele; Isella, Giovanni; Jantsch, Wolfgang; Fanciulli, Marco; Pezzoli, Fabio

2016-01-01

Control of electron spin coherence via external fields is fundamental in spintronics. Its implementation demands a host material that accommodates the desirable but contrasting requirements of spin robustness against relaxation mechanisms and sizeable coupling between spin and orbital motion of the carriers. Here, we focus on Ge, which is a prominent candidate for shuttling spin quantum bits into the mainstream Si electronics. So far, however, the intrinsic spin-dependent phenomena of free electrons in conventional Ge/Si heterojunctions have proved to be elusive because of epitaxy constraints and an unfavourable band alignment. We overcome these fundamental limitations by investigating a two-dimensional electron gas in quantum wells of pure Ge grown on Si. These epitaxial systems demonstrate exceptionally long spin lifetimes. In particular, by fine-tuning quantum confinement we demonstrate that the electron Landé g factor can be engineered in our CMOS-compatible architecture over a range previously inaccessible for Si spintronics. PMID:28000670

Physics and application of persistent spin helix state in semiconductor heterostructures

NASA Astrophysics Data System (ADS)

Kohda, Makoto; Salis, Gian

2017-07-01

In order to utilize the spin degree of freedom in semiconductors, control of spin states and transfer of the spin information are fundamental requirements for future spintronic devices and quantum computing. Spin orbit (SO) interaction generates an effective magnetic field for moving electrons and enables spin generation, spin manipulation and spin detection without using external magnetic field and magnetic materials. However, spin relaxation also takes place due to a momentum dependent SO-induced effective magnetic field. As a result, SO interaction is considered to be a double-edged sword facilitating spin control but preventing spin transport over long distances. The persistent spin helix (PSH) state solves this problem since uniaxial alignment of the SO field with SU(2) symmetry enables the suppression of spin relaxation while spin precession can still be controlled. Consequently, understanding the PSH becomes an important step towards future spintronic technologies for classical and quantum applications. Here, we review recent progress of PSH in semiconductor heterostructures and its device application. Fundamental physics of SO interaction and the conditions of a PSH state in semiconductor heterostructures are discussed. We introduce experimental techniques to observe a PSH and explain both optical and electrical measurements for detecting a long spin relaxation time and the formation of a helical spin texture. After emphasizing the bulk Dresselhaus SO coefficient γ, the application of PSH states for spin transistors and logic circuits are discussed.

Homogeneous microwave field emitted propagating spin waves: Direct imaging and modeling

NASA Astrophysics Data System (ADS)

Lohman, Mathis; Mozooni, Babak; McCord, Jeffrey

2018-03-01

We explore the generation of propagating dipolar spin waves by homogeneous magnetic field excitation in the proximity of the boundaries of magnetic microstructures. Domain wall motion, precessional dynamics, and propagating spin waves are directly imaged by time-resolved wide-field magneto-optical Kerr effect microscopy. The aspects of spin wave generation are clarified by micromagnetic calculations matching the experimental results. The region of dipolar spin wave formation is confined to the local resonant excitation due to non-uniform internal demagnetization fields at the edges of the patterned sample. Magnetic domain walls act as a border for the propagation of plane and low damped spin waves, thus restraining the spin waves within the individual magnetic domains. The findings are of significance for the general understanding of structural and configurational magnetic boundaries for the creation, the propagation, and elimination of spin waves.

Laser-driven clockwise molecular rotation for a transient spinning waveplate.

PubMed

York, Andrew G

2009-08-03

Our simulations show a copropagating pair of laser pulses polarized in two different directions can selectively excite clockwise or counterclockwise molecular rotation in a gas of linear molecules. The resulting birefringence of the gas rotates on a femtosecond timescale and shows a periodic revival structure. The total duration of the pulse pair can be subpicosecond, allowing molecular alignment at the high densities and temperatures necessary to create a transient spinning waveplate.

Application of Roll-Isolated Inertial Measurement Units to the Instrumentation of Spinning Vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

BEADER,MARK E.

Roll-isolated inertial measurement units are developed at Sandia for use in the instrumentation, guidance, and control of rapidly spinning vehicles. Roll-isolation is accomplished by supporting the inertial instrument cluster (gyros and accelerometers) on a single gimbal, the axis of which is parallel to the vehicle's spin axis. A rotary motor on the gimbal is driven by a servo loop to null the roll gyro output, thus inertially stabilizing the gimbal and instrument cluster while the vehicle spins around it. Roll-isolation prevents saturation of the roll gyro by the high vehicle spin rate, and vastly reduces measurement errors arising from gyromore » scale factor and alignment uncertainties. Nine versions of Sandia-developed roll-isolated inertial measurement units have been flown on a total of 27 flight tests since 1972.« less

Magneto-Seebeck effect in spin valves

NASA Astrophysics Data System (ADS)

Zhang, X. M.; Wan, C. H.; Wu, H.; Tang, P.; Yuan, Z. H.; Zhang, Q. T.; Zhang, X.; Tao, B. S.; Fang, C.; Han, X. F.

2017-10-01

The magneto-Seebeck (MS) effect, which is also called magneto-thermo-power, was observed in Co/Cu/Co and NiFe/Cu/Co spin valves. Their Seebeck coefficients in the parallel state were larger than those in the antiparallel state, and the MS ratio defined as (SAP -SP)/SP could reach -9% in our case. The MS effect originated not only from trivial giant magnetoresistance but also from spin current generated due to spin-polarized thermoelectric conductivity of ferromagnetic materials and subsequent modulation of the spin current by different spin configurations in spin valves. A simple Mott two-channel model reproduced a -11% MS effect for the Co/Cu/Co spin valves, qualitatively consistent with our observations. The MS effect could be applied for simultaneously sensing the temperature gradient and the magnetic field and also be possibly applied to determine spin polarization of thermoelectric conductivity and the Seebeck coefficient of ferromagnetic thin films.

Spin valve effect of the interfacial spin accumulation in yttrium iron garnet/platinum bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Lichuan; Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716; Zhang, Dainan

2014-09-29

We report the spin valve effect in yttrium iron garnet/platinum (YIG/Pt) bilayers. The spin Hall effect (SHE) generates spin accumulation at the YIG/Pt interface and can be opened/closed by magnetization switching in the electrical insulator YIG. The interfacial spin accumulation was measured in both YIG/Pt and YIG/Cu/Pt structures using a planar Hall configuration. The spin valve effect remained, even after a 2 nm thick Cu layer was inserted between the YIG and Pt layers, which aimed to exclude the induced magnetization at the YIG/Pt interface. The transverse Hall voltage and switching field were dependent on the applied charge current density. Themore » origin of this behavior can be explained by the SHE induced torque exerted on the domain wall, caused by the transfer of the spin angular momentum from the spin-polarized current to the YIG magnetic moment.« less

Collective Yu-Shiba-Rusinov states in magnetic clusters at superconducting surfaces

NASA Astrophysics Data System (ADS)

Körber, Simon; Trauzettel, Björn; Kashuba, Oleksiy

2018-05-01

We study the properties of collective Yu-Shiba-Rusinov (YSR) states generated by multiple magnetic adatoms (clusters) placed on the surface of a superconductor. For magnetic clusters with equal distances between their constituents, we demonstrate the formation of effectively spin-unpolarized YSR states with subgap energies independent of the spin configuration of the magnetic impurities. We solve the problem analytically for arbitrary spin structure and analyze both spin-polarized (dispersive energy levels) and spin-unpolarized (pinned energy levels) solutions. While the energies of the spin-polarized solutions can be characterized solely by the net magnetic moment of the cluster, the wave functions of the spin-unpolarized solutions effectively decouple from it. This decoupling makes them stable against thermal fluctuation and detectable in scanning tunneling microscopy experiments.

A status report on NASA general aviation stall/spin flight testing

NASA Technical Reports Server (NTRS)

Patton, J. M., Jr.

1980-01-01

The NASA Langley Research Center has undertaken a comprehensive program involving spin tunnel, static and rotary balance wind tunnel, full-scale wind tunnel, free flight radio control model, flight simulation, and full-scale testing. Work underway includes aerodynamic definition of various configurations at high angles of attack, testing of stall and spin prevention concepts, definition of spin and spin recovery characteristics, and development of test techniques and emergency spin recovery systems. This paper presents some interesting results to date for the first aircraft (low-wing, single-engine) in the program, in the areas of tail design, wing leading edge design, mass distribution, center of gravity location, and small airframe changes, with associated pilot observations. The design philosophy of the spin recovery parachute system is discussed in addition to test techniques.

Spin-polarized two-dimensional t2 g electron gas: Ab initio study of EuO interface with oxygen-deficient SrTi O3

NASA Astrophysics Data System (ADS)

Gao, Lingyuan; Demkov, Alexander A.

2018-03-01

Using first-principles calculations we predict the existence of a spin-polarized two-dimensional electron gas (2DEG) at the interface of a ferromagnetic insulator EuO and oxygen-deficient SrTi O3 . The carriers are generated by oxygen vacancies in SrTi O3 near the interface and have predominantly Ti-t2 g orbital character. At the interface, the split-off dx y-derived conduction band of SrTi O3 is fully spin-polarized and the in-gap vacancy-induced state, found below the conduction-band edge, is aligned ferromagnetically with EuO. The calculations suggest a possible mechanism for generating spin-polarized 2DEG for spintronic applications.

Nuclear reactor internals alignment configuration

DOEpatents

Gilmore, Charles B [Greensburg, PA; Singleton, Norman R [Murrysville, PA

2009-11-10

An alignment system that employs jacking block assemblies and alignment posts around the periphery of the top plate of a nuclear reactor lower internals core shroud to align an upper core plate with the lower internals and the core shroud with the core barrel. The distal ends of the alignment posts are chamfered and are closely received within notches machined in the upper core plate at spaced locations around the outer circumference of the upper core plate. The jacking block assemblies are used to center the core shroud in the core barrel and the alignment posts assure the proper orientation of the upper core plate. The alignment posts may alternately be formed in the upper core plate and the notches may be formed in top plate.

Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

DOE PAGES

Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis; ...

2016-12-30

The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis

The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

Fabrication of a Highly Sensitive Single Aligned TiO2 and Gold Nanoparticle Embedded TiO2 Nano-Fiber Gas Sensor.

PubMed

Nikfarjam, Alireza; Hosseini, Seyedsina; Salehifar, Nahideh

2017-05-10

In this research, a single-aligned nanofiber of pure TiO 2 and gold nanoparticle (GNP)-TiO 2 were fabricated using a novel electro-spinning procedure equipped with secondary electrostatic fields on highly sharp triangular and rectangular electrodes provided for gas sensing applications. The sol used for spinning nanofiber consisted of titanium tetraisopropoxide (C 12 H 28 O 4 Ti), acetic acid (CH 3 COOH), ethanol (C 2 H 5 OH), polyvinylpyrrolidone (PVP), and gold nanoparticle solution. FE-SEM, TEM, and XRD were used to characterize the single nanofiber. In triangular electrodes, the electrostatic voltage for aligning single nanofiber between electrodes depends on the angle tip of the electrode, which was around 1.4-2.1, 2-2.9, and 3.2-4.1 kV for 30°, 45°, and 60°, respectively. However, by changing the shape of the electrodes to rectangular samples and by increasing distance between electrodes from 100 to 200 μm, electro-spinning applied voltage decreased. Response of pure TiO 2 single nanofiber sensor was measured for 30-200 ppb carbon monoxide gas. The triangular sample revealed better response and lower threshold than the rectangular sample. Adding appropriate amounts of GNP decreased the operating temperature and increased the responses. CO concentration threshold for the pure TiO 2 and GNP-TiO 2 triangular samples was about 5 ppb and 700 ppt, respectively.

Strain stabilization and thickness dependence of magnetism in epitaxial transition metal monosilicide thin films on Si(111)

NASA Astrophysics Data System (ADS)

Geisler, Benjamin; Kratzer, Peter

2013-09-01

We present a comprehensive study of different 3d transition metal monosilicides in their ground state crystal structure (B20), ranging from equilibrium bulk over biaxially strained bulk to epitaxial thin films on Si(111), by means of density functional theory. The magnetic properties of MnSi and FeSi films are found to be considerably modified due to the epitaxial strain induced by the substrate. In MnSi bulk material, which can be seen as a limit of thick films, we find a strain-induced volume expansion, an increase of the magnetic moments, and a significant rise of the energy difference between different spin configurations. The latter can be associated with an increase of the Curie temperature, which is in accordance with recent experimental results. While a ferromagnetic spin alignment is found to be the ground state also for ultrathin films, we show that for films of intermediate thickness a partially compensating magnetic ordering is more favorable; however, the films retain a net magnetic moment. Furthermore, we analyze the orbital structure in FeSi around the band gap, which can be located somewhere in the density of states for all studied B20 transition metal monosilicides, and find that FeSi becomes metallic and ferromagnetic under epitaxial strain. Finally, the influence of on-site electronic correlation and the reliability of ab initio calculations for 3d transition metal monosilicides are discussed.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, F. L.; González, Guillermo A.

2018-04-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modeled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping and (iii) displaying close encounters. Using the smaller alignment index (SALI) chaos indicator, we further classify bounded orbits into regular, sticky or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnes, Jason W.; Linscott, Ethan; Shporer, Avi, E-mail: jwbarnes@uidaho.edu

We model the asymmetry of the KOI-13.01 transit lightcurve assuming a gravity-darkened rapidly rotating host star in order to constrain the system's spin-orbit alignment and transit parameters. We find that our model can reproduce the Kepler lightcurve for KOI-13.01 with a sky-projected alignment of {lambda} = 23 Degree-Sign {+-} 4 Degree-Sign and with the star's north pole tilted away from the observer by 48 Degree-Sign {+-} 4 Degree-Sign (assuming M{sub *} = 2.05 M{sub Sun }). With both these determinations, we calculate that the net misalignment between this planet's orbit normal and its star's rotational pole is 56 Degree-Sign {+-}more » 4 Degree-Sign . Degeneracies in our geometric interpretation also allow a retrograde spin-orbit angle of 124 Degree-Sign {+-} 4 Degree-Sign . This is the first spin-orbit measurement to come from gravity darkening and is one of only a few measurements of the full (not just the sky-projected) spin-orbit misalignment of an extrasolar planet. We also measure accurate transit parameters incorporating stellar oblateness and gravity darkening: R{sub *} 1.756 {+-} 0.014 R{sub Sun }, R{sub p} = 1.445 {+-} 0.016 R{sub Jup}, and i = 85.{sup 0}9 {+-} 0.{sup 0}4. The new lower planetary radius falls within the planetary mass regime for plausible interior models for the transiting body. A simple initial calculation shows that KOI-13.01's circular orbit is apparently inconsistent with the Kozai mechanism having driven its spin-orbit misalignment; planet-planet scattering and stellar spin migration remain viable mechanisms. Future Kepler data will improve the precision of the KOI-13.01 transit lightcurve, allowing more precise determination of transit parameters and the opportunity to use the Photometric Rossiter-McLaughlin effect to resolve the prograde/retrograde orbit determination degeneracy.« less

Generation of a spin-polarized electron beam by multipole magnetic fields.

PubMed

Karimi, Ebrahim; Grillo, Vincenzo; Boyd, Robert W; Santamato, Enrico

2014-03-01

The propagation of an electron beam in the presence of transverse magnetic fields possessing integer topological charges is presented. The spin-magnetic interaction introduces a nonuniform spin precession of the electrons that gains a space-variant geometrical phase in the transverse plane proportional to the field's topological charge, whose handedness depends on the input electron's spin state. A combination of our proposed device with an electron orbital angular momentum sorter can be utilized as a spin-filter of electron beams in a mid-energy range. We examine these two different configurations of a partial spin-filter generator numerically. The results of this analysis could prove useful in the design of an improved electron microscope. Copyright © 2013 Elsevier B.V. All rights reserved.

Macroscopic Ensembles of Aligned Carbon Nanotubes in Bubble Imprints Studied by Polarized Raman Microscopy

DOE PAGES

Ushiba, Shota; Hoyt, Jordan; Masui, Kyoko; ...

2014-01-01

We study the alignment of single-wall carbon nanotubes (SWCNTs) in bubble imprints through polarized Raman microscopy. A hemispherical bubble containing SWCNTs is pressed against a glass substrate, resulting in an imprint of the bubble membrane with a coffee ring on the substrate. We find that macroscopic ensembles of aligned SWCNTs are obtained in the imprints, in which there are three patterns of orientations: (i) azimuthal alignment on the coffee ring, (ii) radial alignment at the edge of the membrane, and (iii) random orientation at the center of the membrane. We also find that the alignment of SWCNTs in the imprintsmore » can be manipulated by spinning bubbles. The orientation of SWCNTs on the coffee ring is directed radially, which is orthogonal to the case of unspun bubbles. This approach enables one to align SWCNTs in large quantities and in a short time, potentially opening up a wide range of CNT-based electronic and optical applications.« less

Photovoltaic module and interlocked stack of photovoltaic modules

DOEpatents

Wares, Brian S.

2014-09-02

One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame. A plurality of individual male alignment features and a plurality of individual female alignment features are included on each frame. Adjacent photovoltaic modules are interlocked by multiple individual male alignment features on a first module of the adjacent photovoltaic modules fitting into and being surrounded by corresponding individual female alignment features on a second module of the adjacent photovoltaic modules. Other embodiments, features and aspects are also disclosed.

Towards the blackbox computation of magnetic exchange coupling parameters in polynuclear transition-metal complexes: theory, implementation, and application.

PubMed

Phillips, Jordan J; Peralta, Juan E

2013-05-07

We present a method for calculating magnetic coupling parameters from a single spin-configuration via analytic derivatives of the electronic energy with respect to the local spin direction. This method does not introduce new approximations beyond those found in the Heisenberg-Dirac Hamiltonian and a standard Kohn-Sham Density Functional Theory calculation, and in the limit of an ideal Heisenberg system it reproduces the coupling as determined from spin-projected energy-differences. Our method employs a generalized perturbative approach to constrained density functional theory, where exact expressions for the energy to second order in the constraints are obtained by analytic derivatives from coupled-perturbed theory. When the relative angle between magnetization vectors of metal atoms enters as a constraint, this allows us to calculate all the magnetic exchange couplings of a system from derivatives with respect to local spin directions from the high-spin configuration. Because of the favorable computational scaling of our method with respect to the number of spin-centers, as compared to the broken-symmetry energy-differences approach, this opens the possibility for the blackbox exploration of magnetic properties in large polynuclear transition-metal complexes. In this work we outline the motivation, theory, and implementation of this method, and present results for several model systems and transition-metal complexes with a variety of density functional approximations and Hartree-Fock.

Backbending in the {}_{90}^{223}{Th} nucleus: presentation of the consistency of two different experiments

NASA Astrophysics Data System (ADS)

Maquart, G.; Astier, A.; Ducoin, C.; Guinet, D.; Stézowski, O.; Augey, L.; Chaix, L.; Companis, I.; Dudouet, J.; Lehaut, G.; Mancuso, C.; Redon, N.; Vancraeyenest, A.

2017-06-01

The detailed level structure of {}223{Th} has been investigated in measurements of γ radiations following the fusion-evaporation channel of the {}208{Pb}{(}18{{O}},3n{)}223{Th} reaction at 85 MeV beam energy. The present data are extracted from two different experiments performed with the EUROBALL IV and JUROGAM II γ-ray detector array, respectively. The level structure has been extended up to spin 49/2 and 33 new γ-rays have been added using triple-γ coincidence data. The spins and parities of the newly observed states have been confirmed by angular distribution ratios. In addition to the two known yrast bands based on a K=5/2 configuration, a non-yrast band has been established up to spin 35/2. This observation has brought to light a sharp backbending occuring at the highest spins promoting the {}223{Th} as the heavier thorium isotope having an accident observed in its moment of inertia at high spin. We interpret this new structure as based on the same configuration as the yrast band in {}221{Th} having dominant K=1/2 contribution. At the highest spin a backbending occurs around a rotational frequency of {\\hslash }ω =0.23 {MeV}, very close to the one predicted in the {}222{Th} where a sharp transition to a reflection-symmetric shape is expected.

Thermodynamics of emergent magnetic charge screening in artificial spin ice

DOE PAGES

Farhan, Alan; Scholl, Andreas; Petersen, Charlotte F.; ...

2016-09-01

Electric charge screening is a fundamental principle governing the behaviour in a variety of systems in nature. Through reconfiguration of the local environment, the Coulomb attraction between electric charges is decreased, leading, for example, to the creation of polaron states in solids or hydration shells around proteins in water. Here, we directly visualize the real-time creation and decay of screened magnetic charge configurations in a two-dimensional artificial spin ice system, the dipolar dice lattice. By comparing the temperature dependent occurrence of screened and unscreened emergent magnetic charge defects, we determine that screened magnetic charges are indeed a result of localmore » energy reduction and appear as a transient minimum energy state before the system relaxes towards the predicted ground state. These results highlight the important role of emergent magnetic charges in artificial spin ice, giving rise to screened charge excitations and the emergence of exotic low-temperature configurations.« less

Modelling sodium cobaltate by mapping onto magnetic Ising model

NASA Astrophysics Data System (ADS)

Gemperline, Patrick; Morris, David Jonathan Pryce

Fast Ion conductors are a class of crystals that are frequently used as battery materials, especially in smart phones, laptops, and other portable devices. Sodium Cobalt Oxide, NaxCoO2, falls into this class of crystals, but is unique because it possesses the ability to act as a thermoelectric material and a superconductor at different concentrations of Na+. The crystal lattice is mapped onto an Ising Magnetic Spin model and a Monte-Carol Simulation is used to find the most energetically favorable configuration of spins. This spin configuration is mapped back to the crystal lattice resulting in the most stable crystal structure of Sodium Cobalt Oxide at various concentrations. Knowing the atomic structures of the crystals will aid in the research of the materials capabilities and the possible uses of the material commercially. Ohio Supercomputer Center. 1987. Ohio Supercomputer Center. Columbus OH: Ohio Supercomputer Center. and the John Hauck Foundation.

Metric of two balancing Kerr particles in physical parametrization

NASA Astrophysics Data System (ADS)

Manko, V. S.; Ruiz, E.

2015-11-01

The present paper aims at elaborating a completely physical representation for the general 4-parameter family of the extended double-Kerr spacetimes describing two spinning sources in gravitational equilibrium. This involved problem is solved in a concise analytical form by using the individual Komar masses and angular momenta as arbitrary parameters, and the simplest equatorially symmetric specialization of the general expressions obtained by us yields the physical representation for the well-known Dietz-Hoenselaers superextreme case of two balancing identical Kerr constituents. The existence of the physically meaningful "black-hole-superextreme-object" equilibrium configurations permitted by the general solution may be considered as a clear indication that the spin-spin repulsion force might actually be by far stronger than expected earlier, when only the balance between two superextreme Kerr sources was thought possible. We also present the explicit analytical formulas relating the equilibrium states in the double-Kerr and double-Reissner-Nordström configurations.

Thermodynamics of emergent magnetic charge screening in artificial spin ice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farhan, Alan; Scholl, Andreas; Petersen, Charlotte F.

Electric charge screening is a fundamental principle governing the behaviour in a variety of systems in nature. Through reconfiguration of the local environment, the Coulomb attraction between electric charges is decreased, leading, for example, to the creation of polaron states in solids or hydration shells around proteins in water. Here, we directly visualize the real-time creation and decay of screened magnetic charge configurations in a two-dimensional artificial spin ice system, the dipolar dice lattice. By comparing the temperature dependent occurrence of screened and unscreened emergent magnetic charge defects, we determine that screened magnetic charges are indeed a result of localmore » energy reduction and appear as a transient minimum energy state before the system relaxes towards the predicted ground state. These results highlight the important role of emergent magnetic charges in artificial spin ice, giving rise to screened charge excitations and the emergence of exotic low-temperature configurations.« less

Injection and detection of a spin-polarized current in a light-emitting diode

NASA Astrophysics Data System (ADS)

Fiederling, R.; Keim, M.; Reuscher, G.; Ossau, W.; Schmidt, G.; Waag, A.; Molenkamp, L. W.

1999-12-01

The field of magnetoelectronics has been growing in practical importance in recent years. For example, devices that harness electronic spin-such as giant-magnetoresistive sensors and magnetoresistive memory cells-are now appearing on the market. In contrast, magnetoelectronic devices based on spin-polarized transport in semiconductors are at a much earlier stage of development, largely because of the lack of an efficient means of injecting spin-polarized charge. Much work has focused on the use of ferromagnetic metallic contacts, but it has proved exceedingly difficult to demonstrate polarized spin injection. More recently, two groups have reported successful spin injection from an NiFe contact, but the observed effects of the spin-polarized transport were quite small (resistance changes of less than 1%). Here we describe a different approach, in which the magnetic semiconductor BexMnyZn1-x-ySe is used as a spin aligner. We achieve injection efficiencies of 90% spin-polarized current into a non-magnetic semiconductor device. The device used in this case is a GaAs/AlGaAs light-emitting diode, and spin polarization is confirmed by the circular polarization state of the emitted light.

Spin injection into Pt-polymers with large spin-orbit coupling

NASA Astrophysics Data System (ADS)

Sun, Dali; McLaughlin, Ryan; Siegel, Gene; Tiwari, Ashutosh; Vardeny, Z. Valy

2014-03-01

Organic spintronics has entered a new era of devices that integrate organic light-emitting diodes (OLED) in organic spin valve (OSV) geometry (dubbed bipolar organic spin valve, or spin-OLED), for actively manipulating the device electroluminescence via the spin alignment of two ferromagnetic electrodes (Science 337, 204-209, 2012; Appl. Phys. Lett. 103, 042411, 2013). Organic semiconductors that contain heavy metal elements have been widely used as phosphorescent dopants in white-OLEDs. However such active materials are detrimental for OSV operation due to their large spin-orbit coupling (SOC) that may limit the spin diffusion length and thus spin-OLED based on organics with large SOC is a challenge. We report the successful fabrication of OSVs based on pi-conjugated polymers which contain intrachain Platinum atoms (dubbed Pt-polymers). Spin injection into the Pt-polymers is investigated by the giant magnetoresistance (GMR) effect as a function of bias voltage, temperature and polymer layer thickness. From the GMR bias voltage dependence we infer that the ``impendence mismatch'' between ferromagnetic electrodes and Pt-polymer may be suppressed due to the large SOC. Research sponsored by the NSF (Grant No. DMR-1104495) and NSF-MRSEC (DMR 1121252) at the University of Utah.

Interface spins in polycrystalline FeMn/Fe bilayers with small exchange bias

NASA Astrophysics Data System (ADS)

Pires, M. J. M.

2018-04-01

The magnetic moments at the interface between ferromagnetic and antiferromagnetic layers play a central role in exchange biased systems, but their behavior is still not completely understood. In this work, the FeMn/Fe interface in polycrystalline thin films has been studied using conversion electron Mössbauer spectroscopy (CEMS), magneto-optic Kerr effect (MOKE) and micromagnetic simulations. Samples were prepared with 57Fe layers at two distinct depths in order to probe the interface and bulk behaviors. At the equilibrium, the interface moments are randomly oriented while the bulk of the Fe layer has an in-plane magnetic anisotropy. Several models for the interface and anisotropies of the layers were used in the simulations of spin configurations and hysteresis loops. From the whole set of simulations, one can conclude the direct analysis of hysteresis curves is not enough to infer whether the interface has a configuration with spins tilted out of the film plane at equilibrium since different choices of parameters provide similar curves. The simulations have also shown the occurrence of spin clusters at the interface is compatible with CEMS and MOKE measurements.

Two dimensional numerical analysis of aerodynamic characteristics for rotating cylinder on concentrated air flow

NASA Astrophysics Data System (ADS)

Alias, M. S.; Rafie, A. S. Mohd; Marzuki, O. F.; Hamid, M. F. Abdul; Chia, C. C.

2017-12-01

Over the years, many studies have demonstrated the feasibility of the Magnus effect on spinning cylinder to improve lift production, which can be much higher than the traditional airfoil shape. With this characteristic, spinning cylinder might be used as a lifting device for short take-off distance aircraft or unmanned aerial vehicle (UAV). Nonetheless, there is still a gap in research to explain the use of spinning cylinder as a good lifting device. Computational method is used for this study to analyse the Magnus effect, in which two-dimensional finite element numerical analysis method is applied using ANSYS FLUENT software to examine the coefficients of lift and drag, and to investigate the flow field around the rotating cylinder surface body. Cylinder size of 30mm is chosen and several configurations in steady and concentrated air flows have been evaluated. All in all, it can be concluded that, with the right configuration of the concentrated air flow setup, the rotating cylinder can be used as a lifting device for very short take-off since it can produce very high coefficient of lift (2.5 times higher) compared with steady air flow configuration.

Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout

NASA Astrophysics Data System (ADS)

Sukachev, D. D.; Sipahigil, A.; Nguyen, C. T.; Bhaskar, M. K.; Evans, R. E.; Jelezko, F.; Lukin, M. D.

2017-12-01

The negatively charged silicon-vacancy (SiV- ) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date (˜250 ns ) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV- electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV- symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV- spin with 89% fidelity. Coherent control of the SiV- spin with microwave fields is used to demonstrate a spin coherence time T2 of 13 ms and a spin relaxation time T1 exceeding 1 s at 100 mK. These results establish the SiV- as a promising solid-state candidate for the realization of quantum networks.

Creep stability of the proposed AIDA mission target 65803 Didymos: I. Discrete cohesionless granular physics model

NASA Astrophysics Data System (ADS)

Zhang, Yun; Richardson, Derek C.; Barnouin, Olivier S.; Maurel, Clara; Michel, Patrick; Schwartz, Stephen R.; Ballouz, Ronald-Louis; Benner, Lance A. M.; Naidu, Shantanu P.; Li, Junfeng

2017-09-01

As the target of the proposed Asteroid Impact & Deflection Assessment (AIDA) mission, the near-Earth binary asteroid 65803 Didymos represents a special class of binary asteroids, those whose primaries are at risk of rotational disruption. To gain a better understanding of these binary systems and to support the AIDA mission, this paper investigates the creep stability of the Didymos primary by representing it as a cohesionless self-gravitating granular aggregate subject to rotational acceleration. To achieve this goal, a soft-sphere discrete element model (SSDEM) capable of simulating granular systems in quasi-static states is implemented and a quasi-static spin-up procedure is carried out. We devise three critical spin limits for the simulated aggregates to indicate their critical states triggered by reshaping and surface shedding, internal structural deformation, and shear failure, respectively. The failure condition and mode, and shear strength of an aggregate can all be inferred from the three critical spin limits. The effects of arrangement and size distribution of constituent particles, bulk density, spin-up path, and interparticle friction are numerically explored. The results show that the shear strength of a spinning self-gravitating aggregate depends strongly on both its internal configuration and material parameters, while its failure mode and mechanism are mainly affected by its internal configuration. Additionally, this study provides some constraints on the possible physical properties of the Didymos primary based on observational data and proposes a plausible formation mechanism for this binary system. With a bulk density consistent with observational uncertainty and close to the maximum density allowed for the asteroid, the Didymos primary in certain configurations can remain geo-statically stable without requiring cohesion.

Pumped spin and charge currents from applying a microwave field to a quantum dot between two magnetic leads

NASA Astrophysics Data System (ADS)

Zhou, Yun-Qing; Wang, Rui-Qiang; Sheng, L.; Wang, Baigeng; Xing, D. Y.

2008-10-01

The evolution-operator approach is applied to studying photon-electron-pumping effects on a quantum dot connected to two magnetic leads in the presence of both via-dot and over-dot tunneling channels. It is found that a microwave field applied to the quantum dot may give rise to charge and spin pumpings at zero-bias voltage for asymmetric magnetic junctions. More interestingly, a pure spin current can be pumped for symmetric magnetic junctions in the antiparallel magnetization configuration, providing an idea for the design of spin batteries.

Spin Stabilized Impulsively Controlled Missile (SSICM)

NASA Astrophysics Data System (ADS)

Crawford, J. I.; Howell, W. M.

1985-12-01

This patent is for the Spin Stabilized Impulsively Controlled Missile (SSICM). SSICM is a missile configuration which employs spin stabilization, nutational motion, and impulsive thrusting, and a body mounted passive or semiactive sensor to achieve very small miss distances against a high speed moving target. SSICM does not contain an autopilot, control surfaces, a control actuation system, nor sensor stabilization gimbals. SSICM spins at a rate sufficient to provide frequency separation between body motions and inertial target motion. Its impulsive thrusters provide near instantaneous changes in lateral velocity, whereas conventional missiles require a significant time delay to achieve lateral acceleration.

Configuration management program plan for Hanford site systems engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, A.G.

This plan establishes the integrated configuration management program for the evolving technical baseline developed through the systems engineering process. This configuration management program aligns with the criteria identified in the DOE Standard, DOE-STD-1073-93. Included are specific requirements for control of the systems engineering RDD-100 database, and electronic data incorporated in the database that establishes the Hanford site technical baseline.

Multiphoton Coherent Manipulation in Large-Spin Qubits

NASA Astrophysics Data System (ADS)

Bertaina, S.; Chen, L.; Groll, N.; van Tol, J.; Dalal, N. S.; Chiorescu, I.

2009-02-01

Large-spin Mn2+ ions (S=5/2) diluted in a nonmagnetic MgO matrix of high crystalline symmetry are used to realize a six-level system that can be operated by means of multiphoton coherent Rabi oscillations. This spin system has a very small anisotropy which can be tuned in situ to reversibly transform the system between harmonic and nonharmonic level configurations. Decoherence effects are strongly suppressed as a result of the quasi-isotropic electron interaction with the crystal field and with the Mn55 nuclear spins. These results suggest new ways of manipulating, reading, and resetting spin quantum states which can be applied to encode a qubit across several quantum levels.

Spin-polarized electron current from carbon-doped open armchair boron nitride nanotubes: Implication for nano-spintronic devices

NASA Astrophysics Data System (ADS)

Zhou, Gang; Duan, Wenhui

2007-03-01

Spin-polarized density functional calculations show that the substitutional doping of carbon (C) atom at the mouth changes the atomic and spin configurations of open armchair boron nitride nanotubes (BNNTs). The occupied/unoccupied deep gap states are observed with the significant spin-splitting. The structures and spin-polarized properties are basically stable under the considerable electric field, which is important for practical applications. The magnetization mechanism is attributed to the interactions of s, p states between the C and its neighboring B or N atoms. Ultimately, advantageous geometrical and electronic effects mean that C-doped open armchair BNNTs would have promising applications in nano-spintronic devices.

Robustness of topological Hall effect of nontrivial spin textures

NASA Astrophysics Data System (ADS)

Jalil, Mansoor B. A.; Tan, Seng Ghee

2014-05-01

We analyze the topological Hall conductivity (THC) of topologically nontrivial spin textures like magnetic vortices and skyrmions and investigate its possible application in the readback for magnetic memory based on those spin textures. Under adiabatic conditions, such spin textures would theoretically yield quantized THC values, which are related to topological invariants such as the winding number and polarity, and as such are insensitive to fluctuations and smooth deformations. However, in a practical setting, the finite size of spin texture elements and the influence of edges may cause them to deviate from their ideal configurations. We calculate the degree of robustness of the THC output in practical magnetic memories in the presence of edge and finite size effects.

Study of spin-ordering and spin-reorientation transitions in hexagonal manganites through Raman spectroscopy

PubMed Central

Chen, Xiang-Bai; Hien, Nguyen Thi Minh; Han, Kiok; Nam, Ji-Yeon; Huyen, Nguyen Thi; Shin, Seong-Il; Wang, Xueyun; Cheong, S. W.; Lee, D.; Noh, T. W.; Sung, N. H.; Cho, B. K.; Yang, In-Sang

2015-01-01

Spin-wave (magnon) scattering, when clearly observed by Raman spectroscopy, can be simple and powerful for studying magnetic phase transitions. In this paper, we present how to observe magnon scattering clearly by Raman spectroscopy, then apply the Raman method to study spin-ordering and spin-reorientation transitions of hexagonal manganite single crystal and thin films and compare directly with the results of magnetization measurements. Our results show that by choosing strong resonance condition and appropriate polarization configuration, magnon scattering can be clearly observed, and the temperature dependence of magnon scattering can be simple and powerful quantity for investigating spin-ordering as well as spin-reorientation transitions. Especially, the Raman method would be very helpful for investigating the weak spin-reorientation transitions by selectively probing the magnons in the Mn3+ sublattices, while leaving out the strong effects of paramagnetic moments of the rare earth ions. PMID:26300075

Dynamical spin accumulation in large-spin magnetic molecules

NASA Astrophysics Data System (ADS)

Płomińska, Anna; Weymann, Ireneusz; Misiorny, Maciej

2018-01-01

The frequency-dependent transport through a nanodevice containing a large-spin magnetic molecule is studied theoretically in the Kondo regime. Specifically, the effect of magnetic anisotropy on dynamical spin accumulation is of primary interest. Such accumulation arises due to finite components of frequency-dependent conductance that are off diagonal in spin. Here, employing the Kubo formalism and the numerical renormalization group method, we demonstrate that the dynamical transport properties strongly depend on the relative orientation of spin moments in electrodes of the device, as well as on intrinsic parameters of the molecule. In particular, the effect of dynamical spin accumulation is found to be greatly affected by the type of magnetic anisotropy exhibited by the molecule, and it develops for frequencies corresponding to the Kondo temperature. For the parallel magnetic configuration of the device, the presence of dynamical spin accumulation is conditioned by the interplay of ferromagnetic-lead-induced exchange field and the Kondo correlations.

Spin wave propagation in perpendicular magnetized 20 nm Yttrium Iron Garnet with different antenna design

NASA Astrophysics Data System (ADS)

Chen, Jilei; Stueckler, Tobias; Zhang, Youguang; Zhao, Weisheng; Yu, Haiming; Chang, Houchen; Liu, Tao; Wu, Mingzhong; Liu, Chuanpu; Liao, Zhimin; Yu, Dapeng; Fert Beijing research institute Team; Colorado State University Team; Peking University Collaboration

Magnonics offers a new way to transport information using spin waves free of charge current and could lead to a new paradigm in the area of computing. Forward volume (FV) mode spin wave with perpendicular magnetized configuration is suitable for spin wave logic device because it is free of non-reciprocity effect. Here, we study FV mode spin wave propagation in YIG thin film with an ultra-low damping. We integrated differently designed antenna i.e., coplanar waveguide and micro stripline with different dimensions. The k vectors of the spin waves defined by the design of the antenna are calculated using Fourier transform. We show FV mode spin wave propagation results by measuring S12 parameter from vector network analyzer and we extract the group velocity of the FV mode spin wave as well as its dispersion relations.

Non-equilibrium tunneling in zigzag graphene nanoribbon break-junction results in spin filtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Liming; Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville 3010; National ICT Australia, The University of Melbourne, Parkville 3010

Spintronic devices promise new faster and lower energy-consumption electronic systems. Graphene, a versatile material and candidate for next generation electronics, is known to possess interesting spintronic properties. In this paper, by utilizing density functional theory and non-equilibrium green function formalism, we show that Fano resonance can be generated by introducing a break junction in a zigzag graphene nanoribbon (ZGNR). Using this effect, we propose a new spin filtering device that can be used for spin injection. Our theoretical results indicate that the proposed device could achieve high spin filtering efficiency (over 90%) at practical fabrication geometries. Furthermore, our results indicatemore » that the ZGNR break junction lattice configuration can dramatically affect spin filtering efficiency and thus needs to be considered when fabricating real devices. Our device can be fabricated on top of spin transport channel and provides good integration between spin injection and spin transport.« less

Simplified parent-child formalism for spin-0 and spin-1/2 parents

NASA Astrophysics Data System (ADS)

Butcher, J. B.; Jones, H. F.; Milani, P.

1980-06-01

We develop further the parent-child relation, that is the calculation of the cross-sections and correlations of observed particles, typically charged leptons, arising from the decay of long-lived primarily produced “parent” particles. In the high-momentum regime, when the momenta of parent and child are closely aligned, we show how, for spinless parents, the relation can be simplified by the introduction of “fragmentation” functions derived from the invariant inclusive decay distributions. We extend the formalism to the case of spin-1/2 parents and advocate its application to charm production and decay at the quark level.

Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3 Nanosheets.

PubMed

Weber, Daniel; Schoop, Leslie M; Duppel, Viola; Lippmann, Judith M; Nuss, Jürgen; Lotsch, Bettina V

2016-06-08

Spin 1/2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still in demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl3 into the first halide monolayers and the magnetic characterization of the spin 1/2 honeycomb arrangement of turbostratically stacked RuCl3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1/2 state by electron injection into the layers. The restacked, macroscopic pellets of RuCl3 layers lack symmetry along the stacking direction. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at TN = 7 K if the field is aligned parallel to the ab-plane, while the magnetic properties differ from bulk α-RuCl3 if the field is aligned perpendicular to the ab-plane. The deliberate introduction of turbostratic disorder to manipulate the magnetic properties of RuCl3 is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchetti, Barbara; Karsili, Tolga N. V.; Ashfold, Michael N. R., E-mail: mike.ashfold@bristol.ac.uk

Velocity map imaging methods, with a new and improved ion optics design, have been used to explore the near ultraviolet photodissociation dynamics of gas phase 2-bromo- and 2-iodothiophene molecules. In both cases, the ground (X) and spin-orbit excited (X*) (where X = Br, I) atom products formed at the longest excitation wavelengths are found to recoil with fast, anisotropic velocity distributions, consistent with prompt C–X bond fission following excitation via a transition whose dipole moment is aligned parallel to the breaking bond. Upon tuning to shorter wavelengths, this fast component fades and is progressively replaced by a slower, isotropic recoilmore » distribution. Complementary electronic structure calculations provide a plausible explanation for this switch in fragmentation behaviour—namely, the opening of a rival C–S bond extension pathway to a region of conical intersection with the ground state potential energy surface. The resulting ground state molecules are formed with more than sufficient internal energy to sample the configuration space associated with several parent isomers and to dissociate to yield X atom products in tandem with both cyclic and ring-opened partner fragments.« less

Laser cooling of nuclear spin 0 alkali 78Rb

NASA Astrophysics Data System (ADS)

Behr, J. A.; Gorelov, A.; Anholm, M.

2015-05-01

The textbook example for sub-Doppler cooling is a J = 1/2 I = 0 alkali atom in lin ⊥ lin molasses. In the σ+ σ- configuration of a standard MOT, the main sub-Doppler cooling mechanism relies on changing alignment (MF2 population) with the summed linear polarization orientation, but there is no such variation in AC Stark shift for F = 1/2. We have nevertheless looked for signs of sub-Doppler cooling by trapping I = 0 78Rb in a standard MOT and measuring the cloud size as a function of laser detuning and intensity. The 78Rb cloud size does not change significantly with lowered intensity, and expands slightly with detuning, consistent with minimal to no sub-Doppler cooling. Our geometry does show the well-known substantially smaller cloud size with detuning and intensity for I = 3/2 87Rb. Maintaining an I = 0 alkali cloud size with lowered intensity will help our planned β- ν correlation experiments in 38mK decay by suppressing possible production of photoassisted dimers. Supported by NSERC and NRC Canada through TRIUMF.

Interfacial spin-filter assisted spin transfer torque effect in Co/BeO/Co magnetic tunnel junction

NASA Astrophysics Data System (ADS)

Tang, Y.-H.; Chu, F.-C.

2015-03-01

The first-principles calculation is employed to demonstrate the spin-selective transport properties and the non-collinear spin-transfer torque (STT) effect in the newly proposed Co/BeO/Co magnetic tunnel junction. The subtle spin-polarized charge transfer solely at O/Co interface gives rise to the interfacial spin-filter (ISF) effect, which can be simulated within the tight binding model to verify the general expression of STT. This allows us to predict the asymmetric bias behavior of non-collinear STT directly via the interplay between the first-principles calculated spin current densities in collinear magnetic configurations. We believe that the ISF effect, introduced by the combination between wurtzite-BeO barrier and the fcc-Co electrode, may open a new and promising route in semiconductor-based spintronics applications.

Numerical Investigations of the Thermal, Pressure and Size Effects on 2D Spin Crossover Nanoparticles

NASA Astrophysics Data System (ADS)

Harlé, C.; Allal, S. E.; Sohier, D.; Dufaud, T.; Caballero, R.; de Zela, F.; Dahoo, P. R.; Boukheddaden, K.; Linares, J.

2017-12-01

In the framework of the Ising-like model, the thermal and pressure effects on the spin crossover systems are evaluated through two-states fictitious spin operators σ with eigenvalues 𝜎 = -1 and 𝜎 = +1 respectively associated with the low-spin (LS) and highspin (HS) states of each spin-crossover (SCO) molecule. Based on each configurational state, the macroscopic SCO system, is described by the following variables: m=Σ σi, s=Σ σi σj and c=Σ σk standing respectively for the total magnetization, the short-range correlations and surface magnetization. To solve this problem, we first determine the density of macrostates d[m][s][c], giving the number of microscopic configurations with the same m, s and c values. In this contribution, two different ways have been performed to calculate this important quantity: (i) the entropic sampling method, based on Monte Carlo simulations and (ii) a new algorithm based on specific dynamic programming. These two methods were tested on the 2D SCO nanoparticles for which, we calculated the average magnetization < σ> taking into account for short-, long-range interactions as well as for the interaction between surface molecules with their surrounding matrix. We monitored the effect of the pressure, temperature and size on the properties of the SCO nanoparticles.

Spin effects in transport through triangular quantum dot molecule in different geometrical configurations

NASA Astrophysics Data System (ADS)

Wrześniewski, Kacper; Weymann, Ireneusz

2015-07-01

We analyze the spin-resolved transport properties of a triangular quantum dot molecule weakly coupled to external ferromagnetic leads. The calculations are performed by using the real-time diagrammatic technique up to the second-order of perturbation theory, which enables a description of both the sequential and cotunneling processes. We study the behavior of the current and differential conductance in the parallel and antiparallel magnetic configurations, as well as the tunnel magnetoresistance (TMR) and the Fano factor in both the linear and nonlinear response regimes. It is shown that the transport characteristics depend greatly on how the system is connected to external leads. Two specific geometrical configurations of the device are considered—the mirror one, which possesses the reflection symmetry with respect to the current flow direction and the fork one, in which this symmetry is broken. In the case of first configuration we show that, depending on the bias and gate voltages, the system exhibits both enhanced TMR and super-Poissonian shot noise. On the other hand, when the system is in the second configuration, we predict a negative TMR and a negative differential conductance in certain transport regimes. The mechanisms leading to those effects are thoroughly discussed.

Nuclear reactor alignment plate configuration

DOEpatents

Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

2014-01-28

An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

Detweiler's redshift invariant for spinning particles along circular orbits on a Schwarzschild background

NASA Astrophysics Data System (ADS)

Bini, Donato; Damour, Thibault; Geralico, Andrea; Kavanagh, Chris

2018-05-01

We study the metric perturbations induced by a classical spinning particle moving along a circular orbit on a Schwarzschild background, limiting the analysis to effects which are first order in spin. The particle is assumed to move on the equatorial plane and has its spin aligned with the z axis. The metric perturbations are obtained by using two different approaches, i.e., by working in two different gauges: the Regge-Wheeler gauge (using the Regge-Wheeler-Zerilli formalism) and a radiation gauge (using the Teukolsky formalism). We then compute the linear-in-spin contribution to the first-order self-force contribution to Detweiler's redshift invariant up to the 8.5 post-Newtonian order. We check that our result is the same in both gauges, as appropriate for a gauge-invariant quantity, and agrees with the currently known 3.5 post-Newtonian results.

Elongated phase separation domains in spin-cast polymer blend thin films characterized using a panoramic image.

PubMed

Zhang, Hong; Okamura, Yosuke

2018-02-14

Polymer thin films with micro/nano-structures can be prepared by a solvent evaporation induced phase separation process via spin-casting a polymer blend, where the elongated phase separation domains are always inevitable. The striation defect, as a thickness nonunifomity in spin-cast films, is generally coexistent with the elongated domains. Herein, the morphologies of polymer blend thin films are recorded from the spin-cast center to the edge in a panoramic view. The elongated domains are inclined to appear at the ridge regions of striations with increasing radial distance and align radially, exhibiting a coupling between the phase separation morphology and the striation defect that may exist. We demonstrate that the formation of elongated domains is not attributed to shape deformation, but is accomplished in situ. A possible model to describe the initiation and evolution of the polymer blend phase separation morphology during spin-casting is proposed.

Heat-transfer optimization of a high-spin thermal battery

NASA Astrophysics Data System (ADS)

Krieger, Frank C.

Recent advancements in thermal battery technology have produced batteries incorporating a fusible material heat reservoir for operating temperature control that operate reliably under the high spin rates often encountered in ordnance applications. Attention is presently given to the heat-transfer optimization of a high-spin thermal battery employing a nonfusible steel heat reservoir, on the basis of a computer code that simulated the effect of an actual fusible material heat reservoir on battery performance. Both heat paper and heat pellet employing thermal battery configurations were considered.

Vector correlation between the alignment of reactant N{sub 2} (A {sup 3}Σ{sub u}{sup +}) and the alignment of product NO (A {sup 2}Σ{sup +}) rotation in the energy transfer reaction of aligned N{sub 2} (A {sup 3}Σ{sub u}{sup +}) + NO (X {sup 2}Π) → NO (A {sup 2}Σ{sup +}) + N{sub 2} (X {sup 1}Σ{sub g}{sup +})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohoyama, H., E-mail: ohyama@chem.sci.osaka-u.ac.jp

2013-12-21

The vector correlation between the alignment of reactant N{sub 2} (A {sup 3}Σ{sub u}{sup +}) and the alignment of product NO (A {sup 2}Σ{sup +}) rotation has been studied in the energy transfer reaction of aligned N{sub 2} (A {sup 3}Σ{sub u}{sup +}) + NO (X {sup 2}Π) → NO (A {sup 2}Σ{sup +}) + N{sub 2} (X {sup 1}Σ{sub g}{sup +}) under the crossed beam condition at a collision energy of ∼0.07 eV. NO (A {sup 2}Σ{sup +}) emission in the two linear polarization directions (i.e., parallel and perpendicular with respect to the relative velocity vector v{sub R}) hasmore » been measured as a function of the alignment of N{sub 2} (A {sup 3}Σ{sub u}{sup +}) along its molecular axis in the collision frame. The degree of polarization of NO (A {sup 2}Σ{sup +}) emission is found to depend on the alignment angle (θ{sub v{sub R}}) of N{sub 2} (A {sup 3}Σ{sub u}{sup +}) in the collision frame. The shape of the steric opacity function at the two polarization conditions turns out to be extremely different from each other: The steric opacity function at the parallel polarization condition is more favorable for the oblique configuration of N{sub 2} (A {sup 3}Σ{sub u}{sup +}) at an alignment angle of θ{sub v{sub R}} ∼ 45° as compared with that at the perpendicular polarization condition. The alignment of N{sub 2} (A {sup 3}Σ{sub u}{sup +}) is found to give a significant effect on the alignment of NO (A {sup 2}Σ{sup +}) rotation in the collision frame: The N{sub 2} (A {sup 3}Σ{sub u}{sup +}) configuration at an oblique alignment angle θ{sub v{sub R}} ∼ 45° leads to a parallel alignment of NO (A {sup 2}Σ{sup +}) rotation (J-vector) with respect to v{sub R}, while the axial and sideways configurations of N{sub 2} (A {sup 3}Σ{sub u}{sup +}) lead to a perpendicular alignment of NO (A {sup 2}Σ{sup +}) rotation with respect to v{sub R}. These stereocorrelated alignments of the product rotation have a good correlation with the stereocorrelated reactivity observed in the multi-dimensional steric opacity function [H. Ohoyama and S. Maruyama, J. Chem. Phys. 137, 064311 (2012)].« less

A direct method to transform between expansions in the configuration state function and Slater determinant bases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsen, Jeppe, E-mail: jeppe@chem.au.dk

2014-07-21

A novel algorithm is introduced for the transformation of wave functions between the bases of Slater determinants (SD) and configuration state functions (CSF) in the genealogical coupling scheme. By modifying the expansion coefficients as each electron is spin-coupled, rather than performing a single many-electron transformation, the large transformation matrix that plagues previous approaches is avoided and the required number of operations is drastically reduced. As an example of the efficiency of the algorithm, the transformation for a configuration with 30 unpaired electrons and singlet spin is discussed. For this case, the 10 × 10{sup 6} coefficients in the CSF basismore » is obtained from the 150 × 10{sup 6} coefficients in the SD basis in 1 min, which should be compared with the seven years that the previously employed method is estimated to require.« less

Constant field gradient planar coupled cavity structure

DOEpatents

Kang, Y.W.; Kustom, R.L.

1999-07-27

A cavity structure is disclosed having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam. 16 figs.

Constant field gradient planar coupled cavity structure

DOEpatents

Kang, Yoon W.; Kustom, Robert L.

1999-01-01

A cavity structure having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam.

Hydrodynamics of Turning Flocks.

PubMed

Yang, Xingbo; Marchetti, M Cristina

2015-12-18

We present a hydrodynamic model of flocking that generalizes the familiar Toner-Tu equations to incorporate turning inertia of well-polarized flocks. The continuum equations controlled by only two dimensionless parameters, orientational inertia and alignment strength, are derived by coarse-graining the inertial spin model recently proposed by Cavagna et al. The interplay between orientational inertia and bend elasticity of the flock yields anisotropic spin waves that mediate the propagation of turning information throughout the flock. The coupling between spin-current density to the local vorticity field through a nonlinear friction gives rise to a hydrodynamic mode with angular-dependent propagation speed at long wavelengths. This mode becomes unstable as a result of the growth of bend and splay deformations augmented by the spin wave, signaling the transition to complex spatiotemporal patterns of continuously turning and swirling flocks.

Evidence for Coherent Transfer of para-Hydrogen-Induced Polarization at Low Magnetic Fields.

PubMed

Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Kaptein, Robert; Vieth, Hans-Martin; Ivanov, Konstantin L

2013-08-01

We have investigated the mechanism of para-hydrogen-induced polarization (PHIP) transfer from the original strongly aligned protons to other nuclei at low external magnetic fields. Although it is known that PHIP is efficiently transferred at low fields, the nature of the transfer mechanism, that is, coherent spin mixing or cross-relaxation, is not well established. Polarization transfer kinetics for individual protons of styrene was, for the first time, measured and modeled theoretically. Pronounced oscillations were observed indicating a coherent transfer mechanism. Spin coherences were excited by passing through an avoided level crossing of the nuclear spin energy levels. Transfer at avoided level crossings is selective with respect to spin order. Our work provides evidence that the coherent PHIP transfer mechanism is dominant at low magnetic fields.

Periastron advance in spinning black hole binaries: Gravitational self-force from numerical relativity

NASA Astrophysics Data System (ADS)

Le Tiec, Alexandre; Buonanno, Alessandra; Mroué, Abdul H.; Pfeiffer, Harald P.; Hemberger, Daniel A.; Lovelace, Geoffrey; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Bela; Taylor, Nicholas W.; Teukolsky, Saul A.

2013-12-01

We study the general relativistic periastron advance in spinning black hole binaries on quasicircular orbits, with spins aligned or antialigned with the orbital angular momentum, using numerical-relativity simulations, the post-Newtonian approximation, and black hole perturbation theory. By imposing a symmetry by exchange of the bodies’ labels, we devise an improved version of the perturbative result and use it as the leading term of a new type of expansion in powers of the symmetric mass ratio. This allows us to measure, for the first time, the gravitational self-force effect on the periastron advance of a nonspinning particle orbiting a Kerr black hole of mass M and spin S=-0.5M2, down to separations of order 9M. Comparing the predictions of our improved perturbative expansion with the exact results from numerical simulations of equal-mass and equal-spin binaries, we find a remarkable agreement over a wide range of spins and orbital separations.

Low-Field Nuclear Polarization Using Nitrogen Vacancy Centers in Diamonds

NASA Astrophysics Data System (ADS)

Hovav, Y.; Naydenov, B.; Jelezko, F.; Bar-Gill, N.

2018-02-01

It was recently demonstrated that bulk nuclear polarization can be obtained using nitrogen vacancy (NV) color centers in diamonds, even at ambient conditions. This is based on the optical polarization of the NV electron spin, and using several polarization transfer methods. One such method is the nuclear orientation via electron spin locking (NOVEL) sequence, where a spin-locked sequence is applied on the NV spin, with a microwave power equal to the nuclear precession frequency. This was performed at relatively high fields, to allow for both polarization transfer and noise decoupling. As a result, this scheme requires accurate magnetic field alignment in order preserve the NV properties. Such a requirement may be undesired or impractical in many practical scenarios. Here we present a new sequence, termed the refocused NOVEL, which can be used for polarization transfer (and detection) even at low fields. Numerical simulations are performed, taking into account both the spin Hamiltonian and spin decoherence, and we show that, under realistic parameters, it can outperform the NOVEL sequence.

Flip-flopping binary black holes.

PubMed

Lousto, Carlos O; Healy, James

2015-04-10

We study binary spinning black holes to display the long term individual spin dynamics. We perform a full numerical simulation starting at an initial proper separation of d≈25M between equal mass holes and evolve them down to merger for nearly 48 orbits, 3 precession cycles, and half of a flip-flop cycle. The simulation lasts for t=20 000M and displays a total change in the orientation of the spin of one of the black holes from an initial alignment with the orbital angular momentum to a complete antialignment after half of a flip-flop cycle. We compare this evolution with an integration of the 3.5 post-Newtonian equations of motion and spin evolution to show that this process continuously flip flops the spin during the lifetime of the binary until merger. We also provide lower order analytic expressions for the maximum flip-flop angle and frequency. We discuss the effects this dynamics may have on spin growth in accreting binaries and on the observational consequences for galactic and supermassive binary black holes.

Spin reorientation of a nonsymmetric body with energy dissipation

NASA Technical Reports Server (NTRS)

Cenker, R. J.

1973-01-01

Stable rotating semi-rigid bodies were demonstrated analytically, and verified in flights such as Explorer 1 and ATS-5 satellites. The problem arises from the two potential orientations which the final spin vector can take after large angle reorientation from minor to major axis, i.e., along the positive or negative axis of the maximum inertia. Reorientation of a satellite initially spinning about the minor axis using an energy dissipation device may require that the final spin orientation be controlled. Examples of possible applications are the Apogee Motor Assembly with Paired Satellites (AMAPS) configuration, where proper orientation of the thruster is required; and reorientation of ATS-5, where the spin sensitive nature of the despin device (yo-yo mechanism) requires that the final spin vector point is a specified direction.

Tailoring Spin Textures in Complex Oxide Micromagnets

DOE PAGES

Lee, Michael S.; Wynn, Thomas A.; Folven, Erik; ...

2016-09-12

Engineered topological spin textures with submicron dimensions in magnetic materials have emerged in recent years as the building blocks for various spin-based memory devices. Examples of these magnetic configurations include magnetic skyrmions, vortices, and domain walls. Here in this paper, we show the ability to control and characterize the evolution of spin textures in complex oxide micromagnets as a function of temperature through the delicate balance of fundamental materials parameters, micromagnet geometries, and epitaxial strain. These results demonstrate that in order to fully describe the observed spin textures, it is necessary to account for the spatial variation of the magneticmore » parameters within the micromagnet. This study provides the framework to accurately characterize such structures, leading to efficient design of spin-based memory devices based on complex oxide thin films.« less

Giant Spontaneous Hall Effect and Magnetoresistance in La (sub 1-x) Ca(sub x)Co(sub 3) (0.1

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Yueh, N. C.; Samoilov, A. V.; Fu, C. C.; Beach, G.

1997-01-01

In this work, we report the observations of a giant ferromagnetic Hall effect and magnetoresistance in LCCO. The possible physical origin of these phenomena is discussed in the conteext of magnetic clusters and spin transitions due to the multiple spin configurations of the cobaltites.

FALCON Remote Laser Alignment System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamilton, T.W.; Hebner, G.A.

1993-01-01

The FALCON Remote Laser Alignment System is used in a high radiation environment to adjust an optical assembly. The purpose of this report is to provide a description of the hardware used and to present the system configuration. Use of the system has increased the reliability and reproducibility of data as well as significantly reducing personnel radiation exposure. Based upon measured radiation dose, radiation exposure was reduced by at least a factor of two after implementing the remote alignment system.

FALCON Remote Laser Alignment System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamilton, T.W.; Hebner, G.A.

1993-02-01

The FALCON Remote Laser Alignment System is used in a high radiation environment to adjust an optical assembly. The purpose of this report is to provide a description of the hardware used and to present the system configuration. Use of the system has increased the reliability and reproducibility of data as well as significantly reducing personnel radiation exposure. Based upon measured radiation dose, radiation exposure was reduced by at least a factor of two after implementing the remote alignment system.

Ultrasonic alignment of microparticles in nozzle-like geometries

NASA Astrophysics Data System (ADS)

Whittaker, Molly A.; Dauson, Erin R.; Parra-Raad, Jaime; Heard, Robert A.; Oppenheim, Irving J.

2018-03-01

Additive manufacturing (3-D printing) is presently limited by the mechanical properties of the materials, such as polymer resins, that are otherwise efficient and economical for part-forming. Reinforcing the resin with microscale fibers and/or particles would be an effective mechanism to achieve desired mechanical properties such as strength and ductility. Our work combines standing wave ultrasonics and microfluidics to align microparticles in devices that can act as print nozzles, based in part on our prior work with cell sorting. In this paper three different approaches are presented illustrating different engineering tradeoffs, and demonstrating laboratory results of particle alignment. First acoustic resonators are discussed, in which the ultrasonic standing waves result mostly from the mechanical properties of the microfluidic structure, excited by a piezoceramic transducer. Next non-resonant microfluidic structures are discussed, in which ultrasonic standing waves are produced directly by symmetrical transducer deployment. Finally, devices that combine nozzle-like structures, which themselves are suitable acoustic resonators, subjected to symmetrical ultrasonic excitation are presented. We will show that all three configurations will align microparticles, and discuss the tradeoffs among them for subsequent configuration of a print nozzle.

Alignment hierarchies: engineering architecture from the nanometre to the micrometre scale.

PubMed

Kureshi, Alvena; Cheema, Umber; Alekseeva, Tijna; Cambrey, Alison; Brown, Robert

2010-12-06

Natural tissues are built of metabolites, soluble proteins and solid extracellular matrix components (largely fibrils) together with cells. These are configured in highly organized hierarchies of structure across length scales from nanometre to millimetre, with alignments that are dominated by anisotropies in their fibrillar matrix. If we are to successfully engineer tissues, these hierarchies need to be mimicked with an understanding of the interaction between them. In particular, the movement of different elements of the tissue (e.g. molecules, cells and bulk fluids) is controlled by matrix structures at distinct scales. We present three novel systems to introduce alignment of collagen fibrils, cells and growth factor gradients within a three-dimensional collagen scaffold using fluid flow, embossing and layering of construct. Importantly, these can be seen as different parts of the same hierarchy of three-dimensional structure, as they are all formed into dense collagen gels. Fluid flow aligns collagen fibrils at the nanoscale, embossed topographical features provide alignment cues at the microscale and introducing layered configuration to three-dimensional collagen scaffolds provides microscale- and mesoscale-aligned pathways for protein factor delivery as well as barriers to confine protein diffusion to specific spatial directions. These seemingly separate methods can be employed to increase complexity of simple extracellular matrix scaffolds, providing insight into new approaches to directly fabricate complex physical and chemical cues at different hierarchical scales, similar to those in natural tissues.

Reducing the number of templates for aligned-spin compact binary coalescence gravitational wave searches using metric-agnostic template nudging

NASA Astrophysics Data System (ADS)

Indik, Nathaniel; Fehrmann, Henning; Harke, Franz; Krishnan, Badri; Nielsen, Alex B.

2018-06-01

Efficient multidimensional template placement is crucial in computationally intensive matched-filtering searches for gravitational waves (GWs). Here, we implement the neighboring cell algorithm (NCA) to improve the detection volume of an existing compact binary coalescence (CBC) template bank. This algorithm has already been successfully applied for a binary millisecond pulsar search in data from the Fermi satellite. It repositions templates from overdense regions to underdense regions and reduces the number of templates that would have been required by a stochastic method to achieve the same detection volume. Our method is readily generalizable to other CBC parameter spaces. Here we apply this method to the aligned-single-spin neutron star-black hole binary coalescence inspiral-merger-ringdown gravitational wave parameter space. We show that the template nudging algorithm can attain the equivalent effectualness of the stochastic method with 12% fewer templates.

The 2001 April Burst Activation of SGR 1900-14: Pulse Properties and Torque

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith D.

2003-01-01

We report on observations of SGR 1900+14 made with the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAXduring the 2001 April burst activation of the source. Using these data, we measure the spin-down torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (1) their shapes are similar and (1) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spin-down following this flare of the magnitude inferred for the August 27 giant flare. We discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

Unambiguously identifying spin states of transition-metal ions in the Earth (Invited)

NASA Astrophysics Data System (ADS)

Hsu, H.

2010-12-01

The spin state of a transition-metal ion in crystalline solids, defined by the number of unpaired electrons in the ion’s incomplete 3d shell, may vary with many factors, such as temperature, pressure, strain, and the local atomic configuration, to name a few. Such a phenomenon, known as spin-state crossover, plays a crucial role in spintronic materials. Recently, the pressure-induced spin-state crossover in iron-bearing minerals has been recognized to affect the minerals’ structural and elastic properties. However, the detailed mechanism of such crossover in iron-bearing magnesium silicate perovskite, the most abundant mineral in the Earth, remains unclear. A significant part of this confusion arises from the difficulty in reliably extracting the spin state from experiments. For the same reason, the thermally-induced spin-state crossover in lanthanum cobaltite (LaCoO3) has been controversial for more than four decades. In this talk, I will discuss how first-principle calculations can help clarifying these long-standing controversies. In addition to the total energy, equation of state, and elastic properties of each spin state, first-principle calculations also predict the electric field gradient (EFG) at the nucleus of each transition-metal ion. Our calculations showed that the nuclear EFG, a quantity that can be measured via Mössbauer or nuclear magnetic resonance (NMR) spectroscopy, depends primarily on the spin state, irrespective of the concentration or configuration of transition-metal ions. Such robustness makes EFG a unique fingerprint to identify the spin state. The combination of first-principle calculations and Mössbauer/NMR spectroscopy can therefore be a reliable and efficient approach in tackling spin-state crossover problems in the Earth. This work was primarily supported by the MRSEC Program of NSF under Awards Number DMR-0212302 and DMR-0819885, and partially supported by NSF under ATM-0428774 (V-Lab), EAR-1019853, and EAR-0810272. The computations were performed mainly at the Minnesota Supercomputing Institute (MSI).

Biomimetic Nanofibrillation in Two-Component Biopolymer Blends with Structural Analogs to Spider Silk

NASA Astrophysics Data System (ADS)

Xie, Lan; Xu, Huan; Li, Liang-Bin; Hsiao, Benjamin S.; Zhong, Gan-Ji; Li, Zhong-Ming

2016-10-01

Despite the enormous potential in bioinspired fabrication of high-strength structure by mimicking the spinning process of spider silk, currently accessible routes (e.g., microfluidic and electrospinning approaches) still have substantial function gaps in providing precision control over the nanofibrillar superstructure, crystalline morphology or molecular orientation. Here the concept of biomimetic nanofibrillation, by copying the spiders’ spinning principles, was conceived to build silk-mimicking hierarchies in two-phase biodegradable blends, strategically involving the stepwise integration of elongational shear and high-pressure shear. Phase separation confined on nanoscale, together with deformation of discrete phases and pre-alignment of polymer chains, was triggered in the elongational shear, conferring the readiness for direct nanofibrillation in the latter shearing stage. The orderly aligned nanofibrils, featuring an ultralow diameter of around 100 nm and the “rigid-soft” system crosslinked by nanocrystal domains like silk protein dopes, were secreted by fine nanochannels. The incorporation of multiscale silk-mimicking structures afforded exceptional combination of strength, ductility and toughness for the nanofibrillar polymer composites. The proposed spider spinning-mimicking strategy, offering the biomimetic function integration unattainable with current approaches, may prompt materials scientists to pursue biopolymer mimics of silk with high performance yet light weight.

Biomimetic Nanofibrillation in Two-Component Biopolymer Blends with Structural Analogs to Spider Silk.

PubMed

Xie, Lan; Xu, Huan; Li, Liang-Bin; Hsiao, Benjamin S; Zhong, Gan-Ji; Li, Zhong-Ming

2016-10-03

Despite the enormous potential in bioinspired fabrication of high-strength structure by mimicking the spinning process of spider silk, currently accessible routes (e.g., microfluidic and electrospinning approaches) still have substantial function gaps in providing precision control over the nanofibrillar superstructure, crystalline morphology or molecular orientation. Here the concept of biomimetic nanofibrillation, by copying the spiders' spinning principles, was conceived to build silk-mimicking hierarchies in two-phase biodegradable blends, strategically involving the stepwise integration of elongational shear and high-pressure shear. Phase separation confined on nanoscale, together with deformation of discrete phases and pre-alignment of polymer chains, was triggered in the elongational shear, conferring the readiness for direct nanofibrillation in the latter shearing stage. The orderly aligned nanofibrils, featuring an ultralow diameter of around 100 nm and the "rigid-soft" system crosslinked by nanocrystal domains like silk protein dopes, were secreted by fine nanochannels. The incorporation of multiscale silk-mimicking structures afforded exceptional combination of strength, ductility and toughness for the nanofibrillar polymer composites. The proposed spider spinning-mimicking strategy, offering the biomimetic function integration unattainable with current approaches, may prompt materials scientists to pursue biopolymer mimics of silk with high performance yet light weight.

Biomimetic Nanofibrillation in Two-Component Biopolymer Blends with Structural Analogs to Spider Silk

PubMed Central

Xie, Lan; Xu, Huan; Li, Liang-Bin; Hsiao, Benjamin S.; Zhong, Gan-Ji; Li, Zhong-Ming

2016-01-01

Despite the enormous potential in bioinspired fabrication of high-strength structure by mimicking the spinning process of spider silk, currently accessible routes (e.g., microfluidic and electrospinning approaches) still have substantial function gaps in providing precision control over the nanofibrillar superstructure, crystalline morphology or molecular orientation. Here the concept of biomimetic nanofibrillation, by copying the spiders’ spinning principles, was conceived to build silk-mimicking hierarchies in two-phase biodegradable blends, strategically involving the stepwise integration of elongational shear and high-pressure shear. Phase separation confined on nanoscale, together with deformation of discrete phases and pre-alignment of polymer chains, was triggered in the elongational shear, conferring the readiness for direct nanofibrillation in the latter shearing stage. The orderly aligned nanofibrils, featuring an ultralow diameter of around 100 nm and the “rigid−soft” system crosslinked by nanocrystal domains like silk protein dopes, were secreted by fine nanochannels. The incorporation of multiscale silk-mimicking structures afforded exceptional combination of strength, ductility and toughness for the nanofibrillar polymer composites. The proposed spider spinning-mimicking strategy, offering the biomimetic function integration unattainable with current approaches, may prompt materials scientists to pursue biopolymer mimics of silk with high performance yet light weight. PMID:27694989

Robust and Efficient Spin Purification for Determinantal Configuration Interaction.

PubMed

Fales, B Scott; Hohenstein, Edward G; Levine, Benjamin G

2017-09-12

The limited precision of floating point arithmetic can lead to the qualitative and even catastrophic failure of quantum chemical algorithms, especially when high accuracy solutions are sought. For example, numerical errors accumulated while solving for determinantal configuration interaction wave functions via Davidson diagonalization may lead to spin contamination in the trial subspace. This spin contamination may cause the procedure to converge to roots with undesired ⟨Ŝ 2 ⟩, wasting computer time in the best case and leading to incorrect conclusions in the worst. In hopes of finding a suitable remedy, we investigate five purification schemes for ensuring that the eigenvectors have the desired ⟨Ŝ 2 ⟩. These schemes are based on projection, penalty, and iterative approaches. All of these schemes rely on a direct, graphics processing unit-accelerated algorithm for calculating the S 2 c matrix-vector product. We assess the computational cost and convergence behavior of these methods by application to several benchmark systems and find that the first-order spin penalty method is the optimal choice, though first-order and Löwdin projection approaches also provide fast convergence to the desired spin state. Finally, to demonstrate the utility of these approaches, we computed the lowest several excited states of an open-shell silver cluster (Ag 19 ) using the state-averaged complete active space self-consistent field method, where spin purification was required to ensure spin stability of the CI vector coefficients. Several low-lying states with significant multiply excited character are predicted, suggesting the value of a multireference approach for modeling plasmonic nanomaterials.

Experiments in Aligning Threaded Parts Using a Robot Hand

NASA Technical Reports Server (NTRS)

Diftler, M. A.; Walker, I. D.

1999-01-01

Techniques for determining and correcting threaded part alignment using force and angular position data are developed to augment currently limited techniques for align- ing threaded parts. These new techniques are based on backspinning a nut with respect to a bolt and measuring the force change that occurs when the bolt "falls" into the nut. Kinematic models that describe the relationship between threaded parts during backspinning are introduced and are used to show how angular alignment may be determined. The models indicate how to distinguish between the aligned and misaligned cases of a bolt and a nut connection by using axial force data only. In addition, by tracking the in-plane relative attitude of the bolt during spinning, data can be obtained on the direction of the angular misalignment which, in turn, is used to correct the misalignment. Results from experiments using a bolt held in a specialized fixture and a three fingers Stanford/JPL hand are presented.

Planar harmonic polynomials of type B

NASA Astrophysics Data System (ADS)

Dunkl, Charles F.

1999-11-01

The hyperoctahedral group acting on icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>N is the Weyl group of type B and is associated with a two-parameter family of differential-difference operators {Ti:1icons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> iicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> N}. These operators are analogous to partial derivative operators. This paper finds all the polynomials h on icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>N which are harmonic, icons/Journals/Common/Delta" ALT="Delta" ALIGN="TOP"/>Bh = 0 and annihilated by Ti for i>2, where the Laplacian 0305-4470/32/46/308/img1" ALT="(sum). They are given explicitly in terms of a novel basis of polynomials, defined by generating functions. The harmonic polynomials can be used to find wavefunctions for the quantum many-body spin Calogero model.

24 CFR 3285.304 - Pier configuration.

Code of Federal Regulations, 2010 CFR

2010-04-01

... configuration. (a) Concrete blocks. Installation instructions for concrete block piers must be developed in...-bearing (not decorative) concrete blocks must have nominal dimensions of at least 8 inches × 8 inches × 16 inches; (2) The concrete blocks must be stacked with their hollow cells aligned vertically; and (3) When...

Ultrafast giant magnetic cooling effect in ferromagnetic Co/Pt multilayers.

PubMed

Shim, Je-Ho; Ali Syed, Akbar; Kim, Chul-Hoon; Lee, Kyung Min; Park, Seung-Young; Jeong, Jong-Ryul; Kim, Dong-Hyun; Eon Kim, Dong

2017-10-06

The magnetic cooling effect originates from a large change in entropy by the forced magnetization alignment, which has long been considered to be utilized as an alternative environment-friendly cooling technology compared to conventional refrigeration. However, an ultimate timescale of the magnetic cooling effect has never been studied yet. Here, we report that a giant magnetic cooling (up to 200 K) phenomenon exists in the Co/Pt nano-multilayers on a femtosecond timescale during the photoinduced demagnetization and remagnetization, where the disordered spins are more rapidly aligned, and thus magnetically cooled, by the external magnetic field via the lattice-spin interaction in the multilayer system. These findings were obtained by the extensive analysis of time-resolved magneto-optical responses with systematic variation of laser fluence as well as external field strength and direction. Ultrafast giant magnetic cooling observed in the present study can enable a new avenue to the realization of ultrafast magnetic devices.The forced alignment of magnetic moments leads to a large change in entropy, which can be used to reduce the temperature of a material. Here, the authors show that this magnetic cooling effect occurs on a femtosecond time scale in cobalt-platinum nano-multilayers.

133Cs-NMR study on aligned powder of competing spin chain compound Cs2Cu2Mo3O12

NASA Astrophysics Data System (ADS)

Yagi, A.; Matsui, K.; Goto, T.; Hase, M.; Sasaki, T.

2018-03-01

S = 1/2 competing spin chain compound Cs2Cu2Mo3O12 has two dominant exchange interactions of the nearest neighbouring ferromagnetic J 1 = 93 K and the second nearest neighbouring antiferromagnetic J 2 = +33 K, and is expected to show the nematic Tomonaga-Luttinger liquid (TLL) state under high magnetic field region. The recent theoretical study by Sato et al. has shown that in the nematic TLL state, the spin fluctuations are expected to be highly anisotropic, that is, its transverse component is suppressed. Our previous NMR study on the present system showed that the dominant contribution to nuclear spin relaxation comes from the longitudinal component. In order to conclude that the transverse component of spin fluctuations is suppressed, the knowledge of hyperfine coupling is indispensable. This article is solely devoted to investigate the hyperfine coupling of 133Cs-NMR site to prove that the anisotropic part of hyperfine coupling, which connects the nuclear spin relaxation with the transverse spin fluctuations is considerably large to be A an = +770 Oe/μB.

Theoretical study of spin Hall effect in conjugated Organic semiconductors

NASA Astrophysics Data System (ADS)

Mahani, M. R.; Delin, A.

The spin Hall effect (SHE), a direct conversion between electronic and spin currents, is a rapidly growing branch of spintronics. The study of SHE in conjugated polymers has gained momentum recently due to the weak spin-orbit couplings and hyperfine interactions in these materials. Our calculations of SHE based on the recent work, are the result of the misalignment of pi-orbitals in triads consisting of three molecules. In disordered organics, where the electronic conduction is through hopping of the electrons among randomly oriented molecules, instead of identifying a hopping triad to represent the entire system, we numerically solve the master equations for electrical and spin hall conductivities by summing the contributions from all triads in a sufficiently large system. The interference between the direct and indirect hoppings in these triads leads to SHE proportional to the orientation vector of molecule at the first order of spin-orbit coupling. Hence, our results show, the degree of molecular alignment as well as the strength of the spin-orbit coupling can be used to control the SHE in organics.

Coexistence of perfect spin filtering for entangled electron pairs and high magnetic storage efficiency in one setup.

PubMed

Ji, T T; Bu, N; Chen, F J; Tao, Y C; Wang, J

2016-04-14

For Entangled electron pairs superconducting spintronics, there exist two drawbacks in existing proposals of generating entangled electron pairs. One is that the two kinds of different spin entangled electron pairs mix with each other. And the other is a low efficiency of entanglement production. Herein, we report the spin entanglement state of the ferromagnetic insulator (FI)/s-wave superconductor/FI structure on a narrow quantum spin Hall insulator strip. It is shown that not only the high production of entangled electron pairs in wider energy range, but also the perfect spin filtering of entangled electron pairs in the context of no highly spin-polarized electrons, can be obtained. Moreover, the currents for the left and right leads in the antiferromagnetic alignment both can be zero, indicating 100% tunnelling magnetoresistance with highly magnetic storage efficiency. Therefore, the spin filtering for entangled electron pairs and magnetic storage with high efficiencies coexist in one setup. The results may be experimentally demonstrated by measuring the tunnelling conductance and the noise power.

Valency configuration of transition metal impurities in ZnO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petit, Leon; Schulthess, Thomas C; Svane, Axel

2006-01-01

We use the self-interaction corrected local spin-density approximation to investigate the ground state valency configuration of transition metal (TM=Mn, Co) impurities in n- and p-type ZnO. We find that in pure Zn{sub 1-x}TM{sub x}O, the localized TM{sup 2+} configuration is energetically favored over the itinerant d-electron configuration of the local spin density (LSD) picture. Our calculations indicate furthermore that the (+/0) donor level is situated in the ZnO gap. Consequently, for n-type conditions, with the Fermi energy {epsilon}F close to the conduction band minimum, TM remains in the 2+ charge state, while for p-type conditions, with {epsilon}F close to themore » valence band maximum, the 3+ charge state is energetically preferred. In the latter scenario, modeled here by co-doping with N, the additional delocalized d-electron charge transfers into the entire states at the top of the valence band, and hole carriers will only exist, if the N concentration exceeds the TM impurity concentration.« less

Carbon nanotube fiber spun from wetted ribbon

DOEpatents

Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

2014-04-29

A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

Airborne Wind Energy: Implementation and Design for the U.S. Air Force

DTIC Science & Technology

2011-03-01

system. The spinning of the balloon causes what is known as the Magnus effect . The Magnus effect is when the spinning of the balloon causes more of...could not reach using helium alone. The Magnus effect also stabilizes the balloon and helps to keep the system naturally aligned with the wind, within...the horizontal direction, this reduces the projected rotor disk area facing into the wind. The effective area swept out by the wind- rotor is

Nonadiabatic Berry phase in nanocrystalline magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skomski, R.; Sellmyer, D. J.

2016-12-20

In this study, it is investigated how a Berry phase is created in polycrystalline nanomagnets and how the phase translates into an emergent magnetic field and into a topological Hall-effect contribution. The analysis starts directly from the spin of the conduction electrons and does not involve any adiabatic Hamiltonian. Completely random spin alignment in the nanocrystallites does not lead to a nonzero emergent field, but a modulation of the local magnetization does. As an explicit example, we consider a wire with a modulated cone angle.

Planetary explorer liquid propulsion study

NASA Technical Reports Server (NTRS)

Mckevitt, F. X.; Eggers, R. F.; Bolz, C. W.

1971-01-01

An analytical evaluation of several candidate monopropellant hydrazine propulsion system approaches is conducted in order to define the most suitable configuration for the combined velocity and attitude control system for the Planetary Explorer spacecraft. Both orbiter and probe-type missions to the planet Venus are considered. The spacecraft concept is that of a Delta launched spin-stabilized vehicle. Velocity control is obtained through preprogrammed pulse-mode firing of the thrusters in synchronism with the spacecraft spin rate. Configuration selection is found to be strongly influenced by the possible error torques induced by uncertainties in thruster operation and installation. The propulsion systems defined are based on maximum use of existing, qualified components. Ground support equipment requirements are defined and system development testing outlined.

Magnetic moments, E3 transitions and the structure of high-spin core excited states in 211Rn

NASA Astrophysics Data System (ADS)

Poletti, A. R.; Dracoulis, G. D.; Byrne, A. P.; Stuchbery, A. E.; Poletti, S. J.; Gerl, J.; Lewis, P. M.

1985-05-01

The results of g-factor measurements of high-spin states in 211Rn are: Ex = 8856 + Δ' keV (Jπ = 63/2-), g = 0.626(7); 6101 + Δ' KeV (49/2+), 0.766(8); 5347 + Δ' KeV (43/2-), 0.74(2); 3927 + Δ KeV (35/2+), 1.017(12); 1578 + Δ KeV (17/2-), 0.912(9). These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in 211Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously.

Experimental Tests of the Algebraic Cluster Model

NASA Astrophysics Data System (ADS)

Gai, Moshe

2018-02-01

The Algebraic Cluster Model (ACM) of Bijker and Iachello that was proposed already in 2000 has been recently applied to 12C and 16O with much success. We review the current status in 12C with the outstanding observation of the ground state rotational band composed of the spin-parity states of: 0+, 2+, 3-, 4± and 5-. The observation of the 4± parity doublet is a characteristic of (tri-atomic) molecular configuration where the three alpha- particles are arranged in an equilateral triangular configuration of a symmetric spinning top. We discuss future measurement with electron scattering, 12C(e,e’) to test the predicted B(Eλ) of the ACM.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hakjoon; Bac, Seul-Ki; Lee, Sangyeop

We report direct experimental determination of next-nearest-neighbor (NNN) interlayer exchange coupling (IEC) in antiferromagnetically coupled GaMnAs/GaAs:Be multilayers. Magnetoresistance in such multilayers shows step-like transitions as a function of applied magnetic field that corresponds to abrupt changes of spin configuration. By adjusting the field range, one obtains minor hysteresis loops that allow one to determine spin configurations occurring in the multilayer, which in turn can be used to obtain the ratio of NNN IEC to NN IEC. By using this method on a series of GaMnAs/GaAs:Be with different numbers of GaMnAs layers, we obtain this ratio to be 0.23, in goodmore » agreement with theoretical predictions.« less

Learning and inference in a nonequilibrium Ising model with hidden nodes.

PubMed

Dunn, Benjamin; Roudi, Yasser

2013-02-01

We study inference and reconstruction of couplings in a partially observed kinetic Ising model. With hidden spins, calculating the likelihood of a sequence of observed spin configurations requires performing a trace over the configurations of the hidden ones. This, as we show, can be represented as a path integral. Using this representation, we demonstrate that systematic approximate inference and learning rules can be derived using dynamical mean-field theory. Although naive mean-field theory leads to an unstable learning rule, taking into account Gaussian corrections allows learning the couplings involving hidden nodes. It also improves learning of the couplings between the observed nodes compared to when hidden nodes are ignored.

Suppression of Pauli Spin Blockade in Few Hole Laterally Gated Double Quantum Dots

NASA Astrophysics Data System (ADS)

Gaudreau, Louis; Bogan, Alex; Studenikin, Sergei; Korkusinski, Marek; Aers, Geof; Zawadzki, Piotr; Sachrajda, Andy; Tracy, Lisa; Reno, John; Hargett, Terry; National Research Council Team; Sandia Labs Team

Hole spins have attracted increasing attention as candidates for qubits in quantum information applications. The p-type character of their wavefunction leads to smaller hyperfine interaction with the nuclei resulting in longer coherence times. Additionally, strong spin-orbit interaction allows for enhanced all-electrical manipulation of spin qubit states. Single hole spins have been electrically studied in InSb and Si nanowire quantum dots, however, electrostatically confined hole spins in a 2D hole gas have thus far been limited to the many hole regime. In this talk we will present a full description of the two-hole spin spectrum in a lateral GaAs/AlGaAs double quantum. High-bias magneto-transport spectroscopy reveals all four states of the spectrum (singlet and triplets) in both the (1,1) and (2,0) configurations, essential for spin readout based on Pauli spin blockade. We show that spin-flip tunneling between dots is as strong as spin conserving tunneling, a consequence of the strong spin-orbit interaction. This suppresses the Pauli spin blockade. Our results suggest that alternate techniques for single hole spin qubit readout need to be explored.

Pressure driven spin transition in siderite and magnesiosiderite single crystals.

PubMed

Weis, Christopher; Sternemann, Christian; Cerantola, Valerio; Sahle, Christoph J; Spiekermann, Georg; Harder, Manuel; Forov, Yury; Kononov, Alexander; Sakrowski, Robin; Yavaş, Hasan; Tolan, Metin; Wilke, Max

2017-11-28

Iron-bearing carbonates are candidate phases for carbon storage in the deep Earth and may play an important role for the Earth's carbon cycle. To elucidate the properties of carbonates at conditions of the deep Earth, we investigated the pressure driven magnetic high spin to low spin transition of synthetic siderite FeCO 3 and magnesiosiderite (Mg 0.74 Fe 0.26 )CO 3 single crystals for pressures up to 57 GPa using diamond anvil cells and x-ray Raman scattering spectroscopy to directly probe the iron 3d electron configuration. An extremely sharp transition for siderite single crystal occurs at a notably low pressure of 40.4 ± 0.1 GPa with a transition width of 0.7 GPa when using the very soft pressure medium helium. In contrast, we observe a broadening of the transition width to 4.4 GPa for siderite with a surprising additional shift of the transition pressure to 44.3 ± 0.4 GPa when argon is used as pressure medium. The difference is assigned to larger pressure gradients in case of argon. For magnesiosiderite loaded with argon, the transition occurs at 44.8 ± 0.8 GPa showing similar width as siderite. Hence, no compositional effect on the spin transition pressure is observed. The spectra measured within the spin crossover regime indicate coexistence of regions of pure high- and low-spin configuration within the single crystal.

Spin Transfer Torque in Graphene

NASA Astrophysics Data System (ADS)

Lin, Chia-Ching; Chen, Zhihong

2014-03-01

Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

Spin and charge controlled by antisymmetric spin-orbit coupling in a triangular-triple-quantum-dot Kondo system

NASA Astrophysics Data System (ADS)

Koga, M.; Matsumoto, M.; Kusunose, H.

2018-05-01

We study a local antisymmetric spin-orbit (ASO) coupling effect on a triangular-triple-quantum-dot (TTQD) system as a theoretical proposal for a new application of the Kondo physics to nanoscale devices. The electric polarization induced by the Kondo effect is strongly correlated with the spin configurations and molecular orbital degrees of freedom in the TTQD. In particular, an abrupt sign reversal of the emergent electric polarization is associated with a quantum critical point in a magnetic field, which can also be controlled by the ASO coupling that changes the mixing weight of different orbital components in the TTQD ground state.

Highly Efficient Spin-Current Operation in a Cu Nano-Ring

NASA Astrophysics Data System (ADS)

Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

2016-11-01

An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.

ChromA: signal-based retention time alignment for chromatography-mass spectrometry data.

PubMed

Hoffmann, Nils; Stoye, Jens

2009-08-15

We describe ChromA, a web-based alignment tool for chromatography-mass spectrometry data from the metabolomics and proteomics domains. Users can supply their data in open and standardized file formats for retention time alignment using dynamic time warping with different configurable local distance and similarity functions. Additionally, user-defined anchors can be used to constrain and speedup the alignment. A neighborhood around each anchor can be added to increase the flexibility of the constrained alignment. ChromA offers different visualizations of the alignment for easier qualitative interpretation and comparison of the data. For the multiple alignment of more than two data files, the center-star approximation is applied to select a reference among input files to align to. ChromA is available at http://bibiserv.techfak.uni-bielefeld.de/chroma. Executables and source code under the L-GPL v3 license are provided for download at the same location.

An experimental study of the effect of tail configuration on the spinning characteristics of general aviation aircraft. M.S. Thesis; [static wind tunnel force measurements

NASA Technical Reports Server (NTRS)

Ballin, M. G.

1982-01-01

The feasibility of using static wind tunnel tests to obtain information about spin damping characteristics of an isolated general aviation aircraft tail was investigated. A representative tail section was oriented to the tunnel free streamline at angles simulating an equilibrium spin. A full range of normally encountered spin conditions was employed. Results of parametric studies performed to determine the effect of spin damping on several tail design parameters show satisfactory agreement with NASA rotary balance tests. Wing and body interference effects are present in the NASA studies at steep spin attitudes, but agreement improves with increasing pitch angle and spin rate, suggesting that rotational flow effects are minimal. Vertical position of the horizontal stabilizer is found to be a primary parameter affecting yaw damping, and horizontal tail chordwise position induces a substantial effect on pitching moment.

Spin-filtering and giant magnetoresistance effects in polyacetylene-based molecular devices

NASA Astrophysics Data System (ADS)

Chen, Tong; Yan, Shenlang; Xu, Liang; Liu, Desheng; Li, Quan; Wang, Lingling; Long, Mengqiu

2017-07-01

Using the non-equilibrium Green's function formalism in combination with density functional theory, we performed ab initio calculations of spin-dependent electron transport in molecular devices consisting of a polyacetylene (CnHn+1) chain vertically attached to a carbon chain sandwiched between two semi-infinite zigzag-edged graphene nanoribbon electrodes. Spin-charge transport in the device could be modulated to different magnetic configurations by an external magnetic field. The results showed that single spin conduction could be obtained. Specifically, the proposed CnHn+1 devices exhibited several interesting effects, including (dual) spin filtering, spin negative differential resistance, odd-even oscillation, and magnetoresistance (MR). Marked spin polarization with a filtering efficiency of up to 100% over a large bias range was found, and the highest MR ratio for the CnHn+1 junctions reached 4.6 × 104. In addition, the physical mechanisms for these phenomena were also revealed.

Sustainable supply chain design: a configurational approach.

PubMed

Masoumik, S Maryam; Abdul-Rashid, Salwa Hanim; Olugu, Ezutah Udoncy; Raja Ghazilla, Raja Ariffin

2014-01-01

Designing the right supply chain that meets the requirements of sustainable development is a significant challenge. Although there are a considerable number of studies on issues relating to sustainable supply chain design (SSCD) in terms of designing the practices, processes, and structures, they have rarely demonstrated how these components can be aligned to form an effective sustainable supply chain (SSC). Considering this gap in the literature, this study adopts the configurational approach to develop a conceptual framework that could configure the components of a SSC. In this respect, a process-oriented approach is utilized to classify and harmonize the design components. A natural-resource-based view (NRBV) is adopted to determine the central theme to align the design components around. The proposed framework presents three types of SSC, namely, efficient SSC, innovative SSC, and reputed SSC. The study culminates with recommendations concerning the direction for future research.

Sustainable Supply Chain Design: A Configurational Approach

PubMed Central

Masoumik, S. Maryam; Raja Ghazilla, Raja Ariffin

2014-01-01

Designing the right supply chain that meets the requirements of sustainable development is a significant challenge. Although there are a considerable number of studies on issues relating to sustainable supply chain design (SSCD) in terms of designing the practices, processes, and structures, they have rarely demonstrated how these components can be aligned to form an effective sustainable supply chain (SSC). Considering this gap in the literature, this study adopts the configurational approach to develop a conceptual framework that could configure the components of a SSC. In this respect, a process-oriented approach is utilized to classify and harmonize the design components. A natural-resource-based view (NRBV) is adopted to determine the central theme to align the design components around. The proposed framework presents three types of SSC, namely, efficient SSC, innovative SSC, and reputed SSC. The study culminates with recommendations concerning the direction for future research. PMID:24523652

Order by disorder and gaugelike degeneracy in a quantum pyrochlore antiferromagnet.

PubMed

Henley, Christopher L

2006-02-03

The (three-dimensional) pyrochlore lattice antiferromagnet with Heisenberg spins of large spin length S is a highly frustrated model with a macroscopic degeneracy of classical ground states. The zero-point energy of (harmonic-order) spin-wave fluctuations distinguishes a subset of these states. I derive an approximate but illuminating effective Hamiltonian, acting within the subspace of Ising spin configurations representing the collinear ground states. It consists of products of Ising spins around loops, i.e., has the form of a Z2 lattice gauge theory. The remaining ground-state entropy is still infinite but not extensive, being O(L) for system size O(L3). All these ground states have unit cells bigger than those considered previously.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reigel, M. M.; Fowley, M. D.; Pickenheim, B. R.

A soft metal with low wear resistance (6000 series aluminum), was used to minimize run time while maximizing wear rate. Two paddle configurations were tested, with the first four paddles after the augers replaced by the wear paddles. The first configuration was all flat paddles, with the first paddle not aligned with the augers and is consistent with present SPF mixer. The second configuration had helical paddles for the first three stages after the augers and a flat paddle at the fourth stage. The first helical paddle was aligned with the auger flight for the second configuration. The all flatmore » paddle configuration wear rate was approximately double the wear rate of the helical paddles for the first two sets of paddles after the augers. For both configurations, there was little or no wear on the third and fourth paddle sets based on mass change, indicating that the fully wetted premix materials are much less abrasive than the un-wetted or partially wetted premix. Additionally, inspection of the wear surface of the paddles at higher magnification showed the flat paddles were worn much more than the helical and is consistent with the wear rates. Aligning the auger discharge flight with the first set of helical paddles was effective in reducing the wear rate as compared to the flat paddle configuration. Changing the paddle configuration from flat to helical resulted in a slight increase in rheological properties. Although, both tests produced grout-like material that is within the processing rage of the SPF, it should be noted that cement is not included in the premix and water was used rather than salt solution, which does affect the rheology of the fresh grout. The higher rheological properties from the helical wear test are most likely due to the reduced number of shearing paddles in the mixer. In addition, there is variation in the rheological data for each wear test. This is most likely due to the way that the dry feeds enter the mixer from the dry feeder. The premix is discharged from the hopper in an unsteady fashion, where irregular sized clumps were observed leaving the discharge of the auger, though the auger speed is constant.« less

Field-aligned current sources in the high-latitude ionosphere

NASA Technical Reports Server (NTRS)

Barbosa, D. D.

1979-01-01

The paper determines the electric potential in a plane which is fed current from a pair of field-aligned current sheets. The ionospheric conductivity is modelled as a constant with an enhanced conductivity annular ring. It is shown that field-aligned current distributions are arbitrary functions of azimuth angle (MLT) and thus allow for asymmetric potential configurations over the pole cap. In addition, ionospheric surface currents are computed by means of stream functions. Finally, the discussion relates these methods to the electrical characteristics of the magnetosphere.

Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout.

PubMed

Sukachev, D D; Sipahigil, A; Nguyen, C T; Bhaskar, M K; Evans, R E; Jelezko, F; Lukin, M D

2017-12-01

The negatively charged silicon-vacancy (SiV^{-}) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date (∼250  ns) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV^{-} electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV^{-} symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV^{-} spin with 89% fidelity. Coherent control of the SiV^{-} spin with microwave fields is used to demonstrate a spin coherence time T_{2} of 13 ms and a spin relaxation time T_{1} exceeding 1 s at 100 mK. These results establish the SiV^{-} as a promising solid-state candidate for the realization of quantum networks.

Relation between halo spin and cosmic-web filaments at z ≃ 3

NASA Astrophysics Data System (ADS)

González, Roberto E.; Prieto, Joaquin; Padilla, Nelson; Jimenez, Raul

2017-02-01

We investigate the spin evolution of dark matter haloes and their dependence on the number of connected filaments from the cosmic web at high redshift (spin-filament relation hereafter). To this purpose, we have simulated 5000 haloes in the mass range 5 × 109 h-1 M⊙ to 5 × 1011 h-1 M⊙ at z = 3 in cosmological N-body simulations. We confirm the relation found by Prieto et al. (2015) where haloes with fewer filaments have larger spin. We also found that this relation is more significant for higher halo masses, and for haloes with a passive (no major mergers) assembly history. Another finding is that haloes with larger spin or with fewer filaments have their filaments more perpendicularly aligned with the spin vector. Our results point to a picture in which the initial spin of haloes is well described by tidal torque theory and then gets subsequently modified in a predictable way because of the topology of the cosmic web, which in turn is given by the currently favoured Lambda cold dark matter (LCDM) model. Our spin-filament relation is a prediction from LCDM that could be tested with observations.

Spin localization, magnetic ordering, and electronic properties of strongly correlated Ln2O3 sesquioxides (Ln=La, Ce, Pr, Nd)

NASA Astrophysics Data System (ADS)

El-Kelany, Kh. E.; Ravoux, C.; Desmarais, J. K.; Cortona, P.; Pan, Y.; Tse, J. S.; Erba, A.

2018-06-01

Lanthanide sesquioxides are strongly correlated materials characterized by highly localized unpaired electrons in the f band. Theoretical descriptions based on standard density functional theory (DFT) formulations are known to be unable to correctly describe their peculiar electronic and magnetic features. In this study, electronic and magnetic properties of the first four lanthanide sesquioxides in the series are characterized through a reliable description of spin localization as ensured by hybrid functionals of the DFT, which include a fraction of nonlocal Fock exchange. Because of the high localization of the f electrons, multiple metastable electronic configurations are possible for their ground state depending on the specific partial occupation of the f orbitals: the most stable configuration is here found and characterized for all systems. Magnetic ordering is explicitly investigated, and the higher stability of an antiferromagnetic configuration with respect to the ferromagnetic one is predicted. The critical role of the fraction of exchange on the description of their electronic properties (notably, on spin localization and on the electronic band gap) is addressed. In particular, a recently proposed theoretical approach based on a self-consistent definition—through the material dielectric response—of the optimal fraction of exchange in hybrid functionals is applied to these strongly correlated materials.

The qqqqq components and hidden flavor contributions to the baryon magnetic moments

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, C. S.; Li, Q. B.; Riska, D. O.

2006-11-15

The contributions from the qqqqq components to the magnetic moments of the octet as well as the {delta}{sup ++} and {omega}{sup -} decuplet baryons are calculated for the configurations that are expected to have the lowest energy if the hyperfine interaction depends on both spin and flavor. The contributions from the uu,dd, and the ss components are given separately. It is shown that addition of qqqqq admixtures to the ground state baryons can improve the overall description of the magnetic moments of the baryon octet and decuplet in the quark model without SU(3) flavor symmetry breaking, beyond that of themore » different constituent masses of the strange and light-flavor quarks. The explicit flavor (and spin) wave functions for all the possible configurations of the qqqqq components with light and strange qq pairs are given for the baryon octet and decuplet. Admixtures of {approx}10% of the qqqqq configuration where the flavor-spin symmetry is [4]{sub FS}[22]{sub F}[22]{sub S}, which is likely to have the lowest energy, in particular reduces the deviation from the empirical values of the magnetic moments {sigma}{sup -} and the {xi}{sup 0} compared with the static qqq quark model.« less

Recent on-beam tests of wide angle neutron polarization analysis with a 3He spin filter: Magic PASTIS on V20 at HZB

NASA Astrophysics Data System (ADS)

Babcock, E.; Salhi, Z.; Gainov, R.; Woracek, R.; Soltner, H.; Pistel, P.; Beule, F.; Bussmann, K.; Heynen, A.; Kämmerling, H.; Suxdorf, F.; Strobl, M.; Russina, M.; Voigt, J.; Ioffe, A.

2017-06-01

A complete XYZ polarization analysis solution is under development for the new thermal time of flight spectrometer TOPAS [1], to be operated in the coming east neutron guide hall at the MLZ. Polarization Analysis Studies on a Thermal Inelastic Spectrometer, commonly called PASTIS [2], is based on polarized 3He neutron spin filters and an XYZ field configuration for the sample environment and a polarization-preserving neutron guide field. The complete system was designed to provide adiabatic transport of the neutron polarization to the sample position while maintaining the homogeneity of the XYZ field. This system has now been tested on the polarized time-of-flight ESS test beam line V20 at HZB [3]. Down to the minimum wavelength of 1.6 Å on the instrument, the magnetic configuration worked ideally for neutron spin transport while giving full experimental freedom to change between the X, Y or Z field configuration. The 3He cell used was polarized at the 3He lab of the JCNS at the MLZ in Garching and transported to HZB in Berlin via car showing that such a transport is indeed feasible for such experiments. We present results of this test and the next steps forward.

Spin State Control using Oxide Interfaces in LaCoO3-based Heterostructures

NASA Astrophysics Data System (ADS)

Lee, Sangjae; Disa, Ankit; Walker, Frederick; Ahn, Charles

The flexibility of the spin degree of freedom of the Co 3d orbitals in LaCoO3 suggests that they can be changed through careful design of oxide heterostructures. Interfacial coupling and dimensional confinement can be used to control the magnetic exchange, crystal fields, and Hund's coupling, through orbital and charge reconstructions. These parameters control the balance between multiple spin configurations, thereby modifying the magnetic ordering of LaCoO3. We study (LaCoO3)m /(LaTiO3)2 heterostructures grown by molecular beam epitaxy, which allow interfacial charge transfer from Ti to Co, in addition to structural and dimensional constraints. The electronic polarization at the interface and consequent structural distortions suppress the ferromagnetism in the LaCoO3 layers. This effect extends well beyond the interface, with ferromagnetic order absent up to LaCoO3 layer thickness of m =10. We compare the properties of the LaCoO3/LaTiO3heterostructureswithLaCoO3/SrTiO3, to untangle how charge transfer and structural modifications control the spin and magnetic configuration in cobaltates.

Electronic Structures of Silicene Nanoribbons: Two-Edge-Chemistry Modification and First-Principles Study.

PubMed

Yao, Yin; Liu, Anping; Bai, Jianhui; Zhang, Xuanmei; Wang, Rui

2016-12-01

In this paper, we investigate the structural and electronic properties of zigzag silicene nanoribbons (ZSiNRs) with edge-chemistry modified by H, F, OH, and O, using the ab initio density functional theory method and local spin-density approximation. Three kinds of spin polarized configurations are considered: nonspin polarization (NM), ferromagnetic spin coupling for all electrons (FM), ferromagnetic ordering along each edge, and antiparallel spin orientation between the two edges (AFM). The H, F, and OH groups modified 8-ZSiNRs have the AFM ground state. The directly edge oxidized (O1) ZSiNRs yield the same energy and band structure for NM, FM, and AFM configurations, owning to the same s p (2) hybridization. And replacing the Si atoms on the two edges with O atoms (O2) yields FM ground state. The edge-chemistry-modified ZSiNRs all exhibit metallic band structures. And the modifications introduce special edge state strongly localized at the Si atoms in the edge, except for the O1 form. The modification of the zigzag edges of silicene nanoribbons is a key issue to apply the silicene into the field effect transistors (FETs) and gives more necessity to better understand the experimental findings.

Approximate Theoretical Model for the Five Electronic States (Ω = 5/2, 3/2, 3/2, 1/2, 1/2) Arising from the Ground 3d9 Configuration in Nickel Halide Molecules and for Rotational Levels of the Two Ω = 1/2 States in that Manifold

NASA Astrophysics Data System (ADS)

Cheung, Allan S.-C.

2011-06-01

An effective Hamiltonian for a non-rotating diatomic molecule containing only crystal-field and spin-orbit operators has been set up to describe the energies of the five spin-orbit components that arise in the ground electronic configuration of the nickel monohalides. The model assumes that bonding in the nickel halides has the approximate form Ni+X-, with an electronic 3d9 configuration plus closed shells on the Ni+ moiety and a closed shell configuration on the X&- moiety. Least-squares fits of the observed five spin-orbit components of the three lowest electronic states in NiF and NiCl are then carried out in terms of the three crystal field parameters C0, C2, C4 and the spin-orbit coupling constant A. Following this, the usual effective Hamiltonian B(J-L-S)^2 for a rotating diatomic molecule is used to derive expressions for the unusually large Ω-type doubling parameter p in the two Ω = 1/2 states in the 3d9 manifold. These expressions show (for certain sign conventions) that the sum of the two p values should be -2B, but that their difference can vary between -10B and +10B. The theoretical magnitudes for p are in good agreement with the two observed p values for both NiF and NiCl, but the signs are not. The experimental signs can be brought into agreement with the theoretical signs by a fairly massive change in +/- parity assignments in the NiF and NiCl literature. The last part of the talk will focus on the theoretical and experimental implications of these parity changes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaib, Nathan A.; Duncan, Martin J.; Raymond, Sean N., E-mail: nkaib@astro.queensu.ca

Although the 55 Cnc system contains multiple, closely packed planets that are presumably in a coplanar configuration, we use numerical simulations to demonstrate that they are likely to be highly inclined to their parent star's spin axis. Due to perturbations from its distant binary companion, this planetary system precesses like a rigid body about its parent star. Consequently, the parent star's spin axis and the planetary orbit normal likely diverged long ago. Because only the projected separation of the binary is known, we study this effect statistically, assuming an isotropic distribution for wide binary orbits. We find that the mostmore » likely projected spin-orbit angle is {approx}50 Degree-Sign , with a {approx}30% chance of a retrograde configuration. Transit observations of the innermost planet-55 Cnc e-may be used to verify these findings via the Rossiter-McLaughlin effect. 55 Cancri may thus represent a new class of planetary systems with well-ordered, coplanar orbits that are inclined with respect to the stellar equator.« less

Magnetic structure of the swedenborgite CaBa (Co3Fe ) O7 derived by unpolarized neutron diffraction and spherical neutron polarimetry

NASA Astrophysics Data System (ADS)

Qureshi, N.; Díaz, M. T. Fernández; Chapon, L. C.; Senyshyn, A.; Schweika, W.; Valldor, M.

2018-02-01

We present a study that combines polarized and unpolarized neutrons to derive the magnetic structure of the swedenborgite compound CaBa (Co3Fe ) O7. Integrated intensities from a standard neutron diffraction experiment and polarization matrices from spherical neutron polarimetry have been simultaneously analyzed revealing a complex order, which differs from the usual spin configurations on a kagome lattice. We find that the magnetic structure is well described by a combination of two one-dimensional representations corresponding to the magnetic superspace symmetry P 21' , and it consists of spins rotating around an axis close to the [110] direction. Due to the propagation vector q =(1/3 00 ) , this modulation has cycloidal and helicoidal character rendering this system a potential multiferroic. The resulting spin configuration can be mapped onto the classical √{3 }×√{3 } structure of a kagome lattice, and it indicates an important interplay between the kagome and the triangular layers of the crystal structure.

Band structures in near spherical 138Ce

NASA Astrophysics Data System (ADS)

Bhattacharjee, T.; Chanda, S.; Bhattacharyya, S.; Basu, S. K.; Bhowmik, R. K.; Das, J. J.; Pramanik, U. Datta; Ghugre, S. S.; Madhavan, N.; Mukherjee, A.; Mukherjee, G.; Muralithar, S.; Singh, R. P.

2009-06-01

The high spin states of N=80138Ce have been populated in the fusion evaporation reaction 130Te( 12C, 4n) 138Ce at E=65 MeV. The γ transitions belonging to various band structures were detected and characterized using an array of five Clover Germanium detectors. The level scheme has been established up to a maximum spin and excitation energy of 23 ℏ and 9511.3 keV, respectively, by including 53 new transitions. The negative parity ΔI=1 band, developed on the 6536.3 keV 15 level, has been conjectured to be a magnetic rotation band following a semiclassical analysis and comparing the systematics of similar bands in the neighboring nuclei. The said band is proposed to have a four quasiparticle configuration of [πgh]⊗[. Other band structures are interpreted in terms of multi-quasiparticle configurations, based on Total Routhian Surface (TRS) calculations. For the low and medium spin states, a shell model calculation using a realistic two body interaction has been performed using the code OXBASH.

Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy

NASA Astrophysics Data System (ADS)

Mohseni, S. Morteza; Yazdi, H. F.; Hamdi, M.; Brächer, T.; Mohseni, S. Majid

2018-03-01

Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current.

Half-metallic superconducting triplet spin multivalves

NASA Astrophysics Data System (ADS)

Alidoust, Mohammad; Halterman, Klaus

2018-02-01

We study spin switching effects in finite-size superconducting multivalve structures. We examine F1F2SF3 and F1F2SF3F4 hybrids where a singlet superconductor (S) layer is sandwiched among ferromagnet (F) layers with differing thicknesses and magnetization orientations. Our results reveal a considerable number of experimentally viable spin-valve configurations that lead to on-off switching of the superconducting state. For S widths on the order of the superconducting coherence length ξ0, noncollinear magnetization orientations in adjacent F layers with multiple spin axes leads to a rich variety of triplet spin-valve effects. Motivated by recent experiments, we focus on samples where the magnetizations in the F1 and F4 layers exist in a fully spin-polarized half-metallic phase, and calculate the superconducting transition temperature, spatially and energy resolved density of states, and the spin-singlet and spin-triplet superconducting correlations. Our findings demonstrate that superconductivity in these devices can be completely switched on or off over a wide range of magnetization misalignment angles due to the generation of equal-spin and opposite-spin triplet pairings.

Tunnel magnetoresistance of ferrocene molecules

NASA Astrophysics Data System (ADS)

Matsuura, Yukihito

2018-01-01

The spin transport in ferrocene molecules has been examined by using the nonequilibrium Green's function formalism with density functional theory. The ferrocene molecules were sandwiched between the two nickel electrodes in a parallel magnetic configuration, which enhanced the current in comparison with that in an antiparallel spin state and resulting in tunnel magnetoresistance (TMR). The current, having an opposite spin state to that of the ferromagnetic electrode, was the main channel for electron transport. In addition, it became clear that ferrocenylene molecules, having a fulvalene structure with an extended π-conjugation, enhanced the TMR effect.

Alignment relaxation of Ne*(2pi [J = 1]) atoms in He-Ne* glow discharges

NASA Astrophysics Data System (ADS)

Bahrim, Cristian; Khadilkar, Vaibhav; Matsukuma, Hiraku; Hasuo, Masahiro

2009-11-01

Alignment relaxation of the Ne*(2p5 3p; 2pi [J = 1]) atoms (where i = 2, 5, 7 or 10) induced by collisions with He atoms in glow discharges at 77 K < T < 1,000 K are reported. Close-coupling many-channel quantum calculations using a model potential for the Ne*(2p5 3p) - He system are compared with measurements of the alignment relaxation using the LIFS technique and the Hanle effect. The addition of the dipole polarization potential of the Ne*(2pi [J = 1]) atoms to the spin-orbit coupling and the electrostatic interaction between Ne* and He atoms leads to good agreement between theory and experiment.

Hubble Eyes Galaxy as Flat as a Pancake

NASA Image and Video Library

2017-12-08

Located some 25 million light-years away, this new Hubble image shows spiral galaxy ESO 373-8. Together with at least seven of its galactic neighbors, this galaxy is a member of the NGC 2997 group. We see it side-on as a thin, glittering streak across the sky, with all its contents neatly aligned in the same plane. We see so many galaxies like this — flat, stretched-out pancakes — that our brains barely process their shape. But let us stop and ask: Why are galaxies stretched out and aligned like this? Try spinning around in your chair with your legs and arms out. Slowly pull your legs and arms inwards, and tuck them in against your body. Notice anything? You should have started spinning faster. This effect is due to conservation of angular momentum, and it’s true for galaxies, too. This galaxy began life as a humungous ball of slowly rotating gas. Collapsing in upon itself, it spun faster and faster until, like pizza dough spinning and stretching in the air, a disc started to form. Anything that bobbed up and down through this disk was pulled back in line with this motion, creating a streamlined shape. Angular momentum is always conserved — from a spinning galactic disk 25 million light-years away from us, to any astronomer, or astronomer-wannabe, spinning in an office chair. Credit: NASA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

First-principles study of the giant magnetic anisotropy energy in bulk Na4IrO4

NASA Astrophysics Data System (ADS)

Wang, Di; Tang, Feng; Du, Yongping; Wan, Xiangang

2017-11-01

In 5 d transition-metal oxides, novel properties arise from the interplay of electron correlations and spin-orbit interactions. Na4IrO4 , where the 5 d transition-metal Ir atom occupies the center of the square-planar coordination environment, has attracted research interest. Based on density functional theory, we present a comprehensive investigation of electronic and magnetic properties of Na4IrO4 . We propose the magnetic ground-state configuration, and find that the magnetic easy axis is perpendicular to the IrO4 plane. The magnetic anisotropy energy (MAE) of Na4IrO4 is found to be giant. We estimate the magnetic parameters in the generalized symmetry-allowed spin model, and find that the next-nearest-neighbor exchange interaction J2 is much larger than other intersite exchange interactions and results in the magnetic ground-state configuration. The numerical results reveal that the anisotropy of interatomic spin-exchange interaction is quite small and the huge MAE comes from the single-ion anisotropy. This compound has a large spin gap but very narrow spin-wave dispersion, due to the large single-ion anisotropy and quite small intersite exchange couplings. We clarify that these remarkable magnetic features are originated from its highly isolated and low-symmetry IrO4 moiety. We also explore the possibility to further enhance the MAE.

Short-range magentic correlations and dynamic orbital ordering in the thermally activated spin state of LaCoO3

NASA Astrophysics Data System (ADS)

Rosenkranz, S.; Phelan, D.; Louca, D.; Lee, S. H.; Chupas, P. J.; Osborn, R.; Zheng, H.; Mitchell, J. F.

2006-03-01

The cobalt perovskites La1-xSrxCoO3 show intriguing spin, lattice, and orbital properties similar to the ones observed in colossal magnetoresistive manganites. The x=0 parent compound is a non-magnetic insulator at low temperatures, but shows evidence of a spin-state transition of the cobalt ions above 50K from a low-spin to an intermediate or high-spin configuration. Using high resolution, inelastic neutron scattering, we observe a distinct low energy excitation at 0.6meV coincident with the thermally induced spin state transition observed in susceptibility measurements. The thermal activation of this excited spin state also leads to short-range, dynamic ferro- and antiferromagnetic correlations. These observations are consistent with the activation of a zero-field split intermediate spin state as well as the presence of dynamic orbital ordering of these excited states. Work supported by US DOE BES-DMS W-31-109-ENG-38 and NSF DMR-0454672

Spin valves with spin-engineered domain-biasing scheme

NASA Astrophysics Data System (ADS)

Lu, Z. Q.; Pan, G.

2003-06-01

Synthetic spin-filter spin valves with spin-engineered biasing scheme "sub/Ta/NiFe/IrMn/NiFe/NOL/Cu1/CoFe/Cu2/CoFe/Ru/CoFe/IrMn/Ta" were developed. In the structure, the orthogonal magnetic configuration for biasing and pinning field was obtained by one-step magnetic annealing process by means of spin flop, which eliminated the need for two antiferromagnetic materials with distinctively different blocking temperatures and two-step magnetic annealing as in conventional exchange biasing scheme. The longitudinal domain biasing of spin valves was achieved by using interlayer coupling field through Cu1 spacer. By adjusting the thickness of the Cu1 layer, the interlayer coupling biasing field can provide domain stabilization and was sufficiently strong to constrain the magnetization in coherent rotation. This can prevent Barkhausen noises associated with magnetization reversal. We report here a proof of concept study of such a domain-biasing scheme, which has its important technological applications in nanoscale spin valve and magnetic tunneling junction read heads and other spintronic devices.

Electrical spin injection and detection in molybdenum disulfide multilayer channel

PubMed Central

Liang, Shiheng; Yang, Huaiwen; Renucci, Pierre; Tao, Bingshan; Laczkowski, Piotr; Mc-Murtry, Stefan; Wang, Gang; Marie, Xavier; George, Jean-Marie; Petit-Watelot, Sébastien; Djeffal, Abdelhak; Mangin, Stéphane; Jaffrès, Henri; Lu, Yuan

2017-01-01

Molybdenum disulfide has recently emerged as a promising two-dimensional semiconducting material for nano-electronic, opto-electronic and spintronic applications. However, the demonstration of an electron spin transport through a semiconducting MoS2 channel remains challenging. Here we show the evidence of the electrical spin injection and detection in the conduction band of a multilayer MoS2 semiconducting channel using a two-terminal spin-valve configuration geometry. A magnetoresistance around 1% has been observed through a 450 nm long, 6 monolayer thick MoS2 channel with a Co/MgO tunnelling spin injector and detector. It is found that keeping a good balance between the interface resistance and channel resistance is mandatory for the observation of the two-terminal magnetoresistance. Moreover, the electron spin-relaxation is found to be greatly suppressed in the multilayer MoS2 channel with an in-plane spin polarization. The long spin diffusion length (approximately ∼235 nm) could open a new avenue for spintronic applications using multilayer transition metal dichalcogenides. PMID:28387252

Spin-flop coupling and exchange anisotropy in ferromagnetic/antiferromagnetic bilayers

NASA Astrophysics Data System (ADS)

Xu, Xiao-Yong; Hu, Jing-Guo

2009-03-01

By investigating the antiferromagnetic spin configuration, the exchange anisotropy and the interfacial spin-flop coupling in ferromagnetic/antiferromagnetic (FM/AF) bilayers have been discussed in detail. The results show that there are four possible cases for the AF spins, namely the reversible recovering case, irreversible half-rotating case, irreversible reversing and irreversible half-reversing cases. Moreover, the realization of the cases strongly depends on interface quadratic coupling, interface spin-flop (biquadratic) coupling and AF thickness. The magnetic phase diagram in terms of the AF thickness tAF, the interfacial bilinear coupling J1 and the spin-flop coupling J2 has been constructed. The corresponding critical parameters in which the exchange bias will occur or approach saturation have been also presented. Specially, the small spin-flop exchange coupling may result in an exchange bias without the interfacial bilinear exchange coupling. However, in general, the spin-flop exchange coupling can weaken or eliminate the exchange bias, but always enhances the coercivity greatly.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, C.; Klimas, P.; Sanchez-Guillen, J.

For the baby Skyrme model with a specific potential, compacton solutions, i.e., configurations with a compact support and parabolic approach to the vacuum, are derived. Specifically, in the nontopological sector, we find spinning Q-balls and Q-shells, as well as peakons. Moreover, we obtain compact baby skyrmions with nontrivial topological charge. All these solutions may form stable multisoliton configurations provided they are sufficiently separated.

Interplay between resonant tunneling and spin precession oscillations in all-electric all-semiconductor spin transistors

NASA Astrophysics Data System (ADS)

Alomar, M. I.; Serra, Llorenç; Sánchez, David

2016-08-01

We investigate the transmission properties of a spin transistor coupled to two quantum point contacts acting as a spin injector and detector. In the Fabry-Pérot regime, transport is mediated by quasibound states formed between tunnel barriers. Interestingly, the spin-orbit interaction of the Rashba type can be tuned in such a way that nonuniform spin-orbit fields can point along distinct directions at different points of the sample. We discuss both spin-conserving and spin-flipping transitions as the spin-orbit angle of orientation increases from parallel to antiparallel configurations. Spin precession oscillations are clearly seen as a function of the length of the central channel. Remarkably, we find that these oscillations combine with the Fabry-Pérot motion, giving rise to quasiperiodic transmissions in the purely one-dimensional case. Furthermore, we consider the more realistic case of a finite width in the transverse direction and find that the coherent oscillations become deteriorated for moderate values of the spin-orbit strength. Our results then determine the precise role of the spin-orbit intersubband coupling potential in the Fabry-Pérot-Datta-Das intermixed oscillations.

Generalized approximate spin projection calculations of effective exchange integrals of the CaMn4O5 cluster in the S1 and S3 states of the oxygen evolving complex of photosystem II.

PubMed

Isobe, H; Shoji, M; Yamanaka, S; Mino, H; Umena, Y; Kawakami, K; Kamiya, N; Shen, J-R; Yamaguchi, K

2014-06-28

Full geometry optimizations followed by the vibrational analysis were performed for eight spin configurations of the CaMn4O4X(H2O)3Y (X = O, OH; Y = H2O, OH) cluster in the S1 and S3 states of the oxygen evolution complex (OEC) of photosystem II (PSII). The energy gaps among these configurations obtained by vertical, adiabatic and adiabatic plus zero-point-energy (ZPE) correction procedures have been used for computation of the effective exchange integrals (J) in the spin Hamiltonian model. The J values are calculated by the (1) analytical method and the (2) generalized approximate spin projection (AP) method that eliminates the spin contamination errors of UB3LYP solutions. Using J values derived from these methods, exact diagonalization of the spin Hamiltonian matrix was carried out, yielding excitation energies and spin densities of the ground and lower-excited states of the cluster. The obtained results for the right (R)- and left (L)-opened structures in the S1 and S3 states are found to be consistent with available optical and magnetic experimental results. Implications of the computational results are discussed in relation to (a) the necessity of the exact diagonalization for computations of reliable energy levels, (b) magneto-structural correlations in the CaMn4O5 cluster of the OEC of PSII, (c) structural symmetry breaking in the S1 and S3 states, and (d) the right- and left-handed scenarios for the O-O bond formation for water oxidation.

The extraction of the spin structure function, g2 (and g1) at low Bjorken x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ndukum, Luwani Z.

2015-08-01

The Spin Asymmetries of the Nucleon Experiment (SANE) used the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory in Newport News, VA to investigate the spin structure of the proton. The experiment measured inclusive double polarization electron asymmetries using a polarized electron beam, scattered off a solid polarized ammonia target with target polarization aligned longitudinal and near transverse to the electron beam, allowing the extraction of the spin asymmetries A1 and A2, and spin structure functions g1 and g2. Polarized electrons of energies of 4.7 and 5.9 GeV were used. The scattered electrons were detected by a novel, non-magnetic arraymore » of detectors observing a four-momentum transfer range of 2.5 to 6.5 GeV*V. This document addresses the extraction of the spin asymmetries and spin structure functions, with a focus on spin structure function, g2 (and g1) at low Bjorken x. The spin structure functions were measured as a function of x and W in four Q square bins. A full understanding of the low x region is necessary to get clean results for SANE and extend our understanding of the kinematic region at low x.« less

Multidimensional oriented solid-state NMR experiments enable the sequential assignment of uniformly 15N labeled integral membrane proteins in magnetically aligned lipid bilayers.

PubMed

Mote, Kaustubh R; Gopinath, T; Traaseth, Nathaniel J; Kitchen, Jason; Gor'kov, Peter L; Brey, William W; Veglia, Gianluigi

2011-11-01

Oriented solid-state NMR is the most direct methodology to obtain the orientation of membrane proteins with respect to the lipid bilayer. The method consists of measuring (1)H-(15)N dipolar couplings (DC) and (15)N anisotropic chemical shifts (CSA) for membrane proteins that are uniformly aligned with respect to the membrane bilayer. A significant advantage of this approach is that tilt and azimuthal (rotational) angles of the protein domains can be directly derived from analytical expression of DC and CSA values, or, alternatively, obtained by refining protein structures using these values as harmonic restraints in simulated annealing calculations. The Achilles' heel of this approach is the lack of suitable experiments for sequential assignment of the amide resonances. In this Article, we present a new pulse sequence that integrates proton driven spin diffusion (PDSD) with sensitivity-enhanced PISEMA in a 3D experiment ([(1)H,(15)N]-SE-PISEMA-PDSD). The incorporation of 2D (15)N/(15)N spin diffusion experiments into this new 3D experiment leads to the complete and unambiguous assignment of the (15)N resonances. The feasibility of this approach is demonstrated for the membrane protein sarcolipin reconstituted in magnetically aligned lipid bicelles. Taken with low electric field probe technology, this approach will propel the determination of sequential assignment as well as structure and topology of larger integral membrane proteins in aligned lipid bilayers. © Springer Science+Business Media B.V. 2011

Self-aligned blocking integration demonstration for critical sub-30nm pitch Mx level patterning with EUV self-aligned double patterning

NASA Astrophysics Data System (ADS)

Raley, Angélique; Lee, Joe; Smith, Jeffrey T.; Sun, Xinghua; Farrell, Richard A.; Shearer, Jeffrey; Xu, Yongan; Ko, Akiteru; Metz, Andrew W.; Biolsi, Peter; Devilliers, Anton; Arnold, John; Felix, Nelson

2018-04-01

We report a sub-30nm pitch self-aligned double patterning (SADP) integration scheme with EUV lithography coupled with self-aligned block technology (SAB) targeting the back end of line (BEOL) metal line patterning applications for logic nodes beyond 5nm. The integration demonstration is a validation of the scalability of a previously reported flow, which used 193nm immersion SADP targeting a 40nm pitch with the same material sets (Si3N4 mandrel, SiO2 spacer, Spin on carbon, spin on glass). The multi-color integration approach is successfully demonstrated and provides a valuable method to address overlay concerns and more generally edge placement error (EPE) as a whole for advanced process nodes. Unbiased LER/LWR analysis comparison between EUV SADP and 193nm immersion SADP shows that both integrations follow the same trend throughout the process steps. While EUV SADP shows increased LER after mandrel pull, metal hardmask open and dielectric etch compared to 193nm immersion SADP, the final process performance is matched in terms of LWR (1.08nm 3 sigma unbiased) and is only 6% higher than 193nm immersion SADP for average unbiased LER. Using EUV SADP enables almost doubling the line density while keeping most of the remaining processes and films unchanged, and provides a compelling alternative to other multipatterning integrations, which present their own sets of challenges.

Orbitally dependent kinetic exchange in a heterobimetallic pair: Ferromagnetic spin alignment and magnetic anisotropy in the cyano-bridged Cr(III)Fe(II) dimer

NASA Astrophysics Data System (ADS)

Palii, A. V.; Tsukerblat, B. S.; Verdaguer, M.

2002-11-01

The problem of the kinetic exchange interaction in the cyanide-bridged heterobinuclear dimers involving orbitally degenerate transition metal ions is considered. The developed approach is based on the concept of the effective Hamiltonian of the orbitally dependent kinetic exchange. We deduce this many-electron Hamiltonian on the microscopic background so that all relevant biorbital transfer processes are taken into account as well as the properties of the many-electron states. The bioctahedral cyanide-bridged Cr(III)Fe(II) dimer is considered in detail as an example distinctly exhibiting new quantitative and qualitative features of the orbitally dependent exchange and as a structural unit of three-dimensional ferromagnetic crystals {Fe(II)3)Cr(III)(CN62}[middle dot]13H2O. The proposed mechanism of the kinetic exchange involves the electron transfer from the double occupied t2 orbitals of Fe(II) [ground state 5T2(t2)4e2] to the half occupied t2 orbitals of Cr(III) [ground state 4A2(t2)3] resulting in the charge transfer state 3T1(t2)4Cr(II)- 6A1(t2)3e2 Fe(III) and the transfer between the half-occupied t2 orbitals of the metal ions resulting in the charge transfer state 3T1(t2)4Cr(II)- 4T2(t2)3e2 Fe(III). The effective Hamiltonian of the orbitally dependent exchange for the Cr(III)Fe(II) pair deduced within this theoretical framework describes competitive ferro- and antiferromagnetic contributions arising from these two charge transfer states. This Hamiltonian leads to a complex energy pattern, consisting of two interpenetrating Heisenberg-like schemes, one exhibiting ferromagnetic and another one antiferromagnetic splitting. The condition for the ferromagnetic spin alignment in the ground state is deduced. The orbitally dependent terms of the Hamiltonian are shown to give rise to a strong magnetic anisotropy of the system, this result as well as the condition for the spin alignment in the ground term are shown to be out of the scope of the Goodenough-Kanamori rules. Along with the full spin S the energy levels are labeled by the orbital quantum numbers providing thus the direct information about the magnetic anisotropy of the system. Under a reasonable estimation of the excitation energies based on the optical absorption data we conclude that the kinetic exchange in the cyanide-bridged Cr(III)Fe(II) pair leads to the ferromagnetic spin alignment exhibiting at the same time strong axial magnetic anisotropy with C4 easy axis of magnetization.

Relative properties of smooth terminating bands

NASA Astrophysics Data System (ADS)

Afanasjev, A. V.; Ragnarsson, I.

1998-01-01

The relative properties of smooth terminating bands observed in the A ∼ 110 mass region are studied within the effective alignment approach. Theoretical values of ietf are calculated using the configuration-dependent shell-correction model with the cranked Nilsson potential. Reasonable agreement with experiment shows that previous interpretations of these bands are consistent with the present study. Contrary to the case of superdeformed bands, the effective alignments of these bands deviate significantly from the pure single-particle alignments of the corresponding orbitals. This indicates that in the case of smooth terminating bands, the effects associated with changes in equilibrium deformations contribute significantly to the effective alignment.

Photovoltaic module and interlocked stack of photovoltaic modules

DOEpatents

Wares, Brian S.

2012-09-04

One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame having at least a top member and a bottom member. A plurality of alignment features are included on the top member of each frame, and a plurality of alignment features are included on the bottom member of each frame. Adjacent photovoltaic modules are interlocked by the alignment features on the top member of a lower module fitting together with the alignment features on the bottom member of an upper module. Other embodiments, features and aspects are also disclosed.

Is perpendicular magnetic anisotropy essential to all-optical ultrafast spin reversal in ferromagnets?

NASA Astrophysics Data System (ADS)

Zhang, G. P.; Bai, Y. H.; George, Thomas F.

2017-10-01

All-optical spin reversal presents a new opportunity for spin manipulations, free of a magnetic field. Most of all-optical-spin-reversal ferromagnets are found to have a perpendicular magnetic anisotropy (PMA), but it has been unknown whether PMA is necessary for spin reversal. Here we theoretically investigate magnetic thin films with either PMA or in-plane magnetic anisotropy (IMA). Our results show that spin reversal in IMA systems is possible, but only with a longer laser pulse and within a narrow laser parameter region. Spin reversal does not show a strong helicity dependence where the left- and right-circularly polarized light lead to the identical results. By contrast, the spin reversal in PMA systems is robust, provided both the spin angular momentum and laser field are strong enough while the magnetic anisotropy itself is not too strong. This explains why experimentally the majority of all-optical spin-reversal samples are found to have strong PMA and why spins in Fe nanoparticles only cant out of plane. It is the laser-induced spin-orbit torque that plays a key role in the spin reversal. Surprisingly, the same spin-orbit torque results in laser-induced spin rectification in spin-mixed configuration, a prediction that can be tested experimentally. Our results clearly point out that PMA is essential to spin reversal, though there is an opportunity for in-plane spin reversal.

The Alignment Test System for AXAF-I's High Resolution Mirror Assembly

NASA Technical Reports Server (NTRS)

Waldman, Mark

1995-01-01

The AXAF-1 High Resolution Mirror Assembly (HRMA) consists of four nested mirror pairs of Wolter Type-1 grazing incidence optics. The HRMA assembly and alignment will take place in a vibration-isolated, cleanliness class 100, 18 meter high tower at an Eastman Kodak Company facility in Rochester, NY. Each mirror pair must be aligned such that its image is coma-free, and the four pairs must be aligned such that their images are coincident. In addition, both the HRMA optical axis and focal point must be precisely known with respect to physical references on the HRMA. The alignment of the HRMA mirrors is measured by the HRMA Alignment Test System (HATS), which is an integral part of the tower facility. The HATS is configured as a double-pass, autocollimating Hartmann test where each mirror aperture is scanned to determine the state of alignment. This paper will describe the design and operation of the HATS.

Stability of a dual-spin satellite with two dampers

NASA Technical Reports Server (NTRS)

Alfriend, K. T.; Hubert, C. H.

1974-01-01

The rotational stability of a dual-spin satellite consisting of a main body and a symmetric rotor, both spinning about a common axis, is investigated. The main body is equipped with a spring-mass damper, while a partially filled viscous ring damper is mounted on the rapidly spinning rotor. The effect of fluid motion on the rotational stability of the satellite is calculated, considering the fluid as a single particle moving in a tube with viscous damping. Time constants are obtained by solving approximate equations of motion for the nutation-synchronous and the spin-synchronous modes, and the results are found to agree well with the numerical integrations of the exact equations. A limit cycle may exist for some configurations; the nutation angle tends to increase in such cases.

Extremal Optimization for estimation of the error threshold in topological subsystem codes at T = 0

NASA Astrophysics Data System (ADS)

Millán-Otoya, Jorge E.; Boettcher, Stefan

2014-03-01

Quantum decoherence is a problem that arises in implementations of quantum computing proposals. Topological subsystem codes (TSC) have been suggested as a way to overcome decoherence. These offer a higher optimal error tolerance when compared to typical error-correcting algorithms. A TSC has been translated into a planar Ising spin-glass with constrained bimodal three-spin couplings. This spin-glass has been considered at finite temperature to determine the phase boundary between the unstable phase and the stable phase, where error recovery is possible.[1] We approach the study of the error threshold problem by exploring ground states of this spin-glass with the Extremal Optimization algorithm (EO).[2] EO has proven to be a effective heuristic to explore ground state configurations of glassy spin-systems.[3

Doping-induced spin-orbit splitting in Bi-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Aras, Mehmet; Güler-Kılıç, Sümeyra; Kılıç, ćetin

2017-04-01

Our predictions, based on density-functional calculations, reveal that surface doping of ZnO nanowires with Bi leads to a linear-in-k splitting of the conduction-band states, through spin-orbit interaction, due to the lowering of the symmetry in the presence of the dopant. This finding implies that spin polarization of the conduction electrons in Bi-doped ZnO nanowires could be controlled with applied electric (as opposed to magnetic) fields, making them candidate materials for spin-orbitronic applications. Our findings also show that the degree of spin splitting could be tuned by adjusting the dopant concentration. Defect calculations and ab initio molecular dynamics simulations indicate that stable doping configurations exhibiting the foregoing linear-in-k splitting could be realized under reasonable thermodynamic conditions.

The spin-dependent electronic transport properties of M(dcdmp)2 (M = Cu, Au, Co, Ni) molecular devices based on zigzag graphene nanoribbon electrodes

NASA Astrophysics Data System (ADS)

Li, Dongde; Wu, Di; Zhang, Xiaojiao; Zeng, Bowen; Li, Mingjun; Duan, Haiming; Yang, Bingchu; Long, Mengqiu

2018-05-01

The spin-dependent electronic transport properties of M(dcdmp)2 (M = Cu, Au, Co, Ni; dcdmp = 2,3-dicyano-5,6-dimercaptopyrazyne) molecular devices based on zigzag graphene nanoribbon (ZGNR) electrodes were investigated by density functional theory combined nonequilibrium Green's function method (DFT-NEGF). Our results show that the spin-dependent transport properties of the M(dcdmp)2 molecular devices can be controlled by the spin configurations of the ZGNR electrodes, and the central 3d-transition metal atom can introduce a larger magnetism than that of the nonferrous metal one. Moreover, the perfect spin filtering effect, negative differential resistance, rectifying effect and magnetic resistance phenomena can be observed in our proposed M(dcdmp)2 molecular devices.

Can spin-up go down in a Stern-Gerlach device? The propagator approach to Stern-Gerlach wavepacket dynamics

NASA Astrophysics Data System (ADS)

Hsu, Bailey; van Huele, Jean-Francois

2009-10-01

The Stern-Gerlach effect (SGE) is iconic for visualizing spin. We analyze the evolution of atomic wavepackets by constructing exact solutions using propagators in SGE field configurations in different approximations. We contrast our results with the standard presentation of the SGE in textbooks and literature and illustrate with visual animations in 2D and 3D.

Recovery of spinning satellites

NASA Technical Reports Server (NTRS)

Coppey, J. M.; Mahaffey, W. R.

1977-01-01

The behavior of a space tug and a spinning satellite in a coupled configuration was simulated and analyzed. A docking concept was developed to investigate the requirements pertaining to the design of a docking interface. Sensing techniques and control requirements for the chase vehicle were studied to assess the feasibility of an automatic docking. The effects of nutation dampers and liquid propellant slosh motion upon the docking transient were investigated.

A Fuzzy Logic Based Controller for the Automated Alignment of a Laser-beam-smoothing Spatial Filter

NASA Technical Reports Server (NTRS)

Krasowski, M. J.; Dickens, D. E.

1992-01-01

A fuzzy logic based controller for a laser-beam-smoothing spatial filter is described. It is demonstrated that a human operator's alignment actions can easily be described by a system of fuzzy rules of inference. The final configuration uses inexpensive, off-the-shelf hardware and allows for a compact, readily implemented embedded control system.

Precision laser aiming system

DOEpatents

Ahrens, Brandon R [Albuquerque, NM; Todd, Steven N [Rio Rancho, NM

2009-04-28

A precision laser aiming system comprises a disrupter tool, a reflector, and a laser fixture. The disrupter tool, the reflector and the laser fixture are configurable for iterative alignment and aiming toward an explosive device threat. The invention enables a disrupter to be quickly and accurately set up, aligned, and aimed in order to render safe or to disrupt a target from a standoff position.

A systematic experimental investigation of significant parameters affecting model tire hydroplaning

NASA Technical Reports Server (NTRS)

Wray, G. A.; Ehrlich, I. R.

1973-01-01

The results of a comprehensive parametric study of model and small pneumatic tires operating on a wet surface are presented. Hydroplaning inception (spin down) and rolling restoration (spin up) are discussed. Conclusions indicate that hydroplaning inception occurs at a speed significantly higher than the rolling restoration speed. Hydroplaning speed increases considerably with tread depth, surface roughness and tire inflation pressure of footprint pressure, and only moderately with increased load. Water film thickness affects spin down speed only slightly. Spin down speed varies inversely as approximately the one-sixth power of film thickness. Empirical equations relating tire inflation pressure, normal load, tire diameter and water film thickness have been generated for various tire tread and surface configurations.

Arbitrary helicity control of circularly polarized light from lateral-type spin-polarized light-emitting diodes at room temperature

NASA Astrophysics Data System (ADS)

Nishizawa, Nozomi; Aoyama, Masaki; Roca, Ronel C.; Nishibayashi, Kazuhiro; Munekata, Hiro

2018-05-01

We demonstrate arbitrary helicity control of circularly polarized light (CPL) emitted at room temperature from the cleaved side facet of a lateral-type spin-polarized light-emitting diode (spin-LED) with two ferromagnetic electrodes in an antiparallel magnetization configuration. Driving alternate currents through the two electrodes results in polarization switching of CPL with frequencies up to 100 kHz. Furthermore, tuning the current density ratio in the two electrodes enables manipulation of the degree of circular polarization. These results demonstrate arbitrary electrical control of polarization with high speed, which is required for the practical use of lateral-type spin-LEDs as monolithic CPL light sources.

Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

NASA Astrophysics Data System (ADS)

Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

2016-12-01

Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior.

Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics

DOE PAGES

Zhong, Ding; Seyler, Kyle L.; Linpeng, Xiayu; ...

2017-05-31

The integration of magnetic material with semiconductors has been fertile ground for fundamental science as well as of great practical interest toward the seamless integration of information processing and storage. We create van der Waals heterostructures formed by an ultrathin ferromagnetic semiconductor CrI 3 and a monolayer of WSe 2. We observe unprecedented control of the spin and valley pseudospin in WSe 2, where we detect a large magnetic exchange field of nearly 13 T and rapid switching of the WSe 2 valley splitting and polarization via flipping of the CrI 3 magnetization. The WSe2 photoluminescence intensity strongly depends onmore » the relative alignment between photoexcited spins in WSe 2 and the CrI 3 magnetization, because of ultrafast spin-dependent charge hopping across the heterostructure interface. The photoluminescence detection of valley pseudospin provides a simple and sensitive method to probe the intriguing domain dynamics in the ultrathin magnet, as well as the rich spin interactions within the heterostructure.« less

Magnetic order in a frustrated two-dimensional atom lattice at a semiconductor surface.

PubMed

Li, Gang; Höpfner, Philipp; Schäfer, Jörg; Blumenstein, Christian; Meyer, Sebastian; Bostwick, Aaron; Rotenberg, Eli; Claessen, Ralph; Hanke, Werner

2013-01-01

Two-dimensional electron systems, as exploited for device applications, can lose their conducting properties because of local Coulomb repulsion, leading to a Mott-insulating state. In triangular geometries, any concomitant antiferromagnetic spin ordering can be prevented by geometric frustration, spurring speculations about 'melted' phases, known as spin liquid. Here we show that for a realization of a triangular electron system by epitaxial atom adsorption on a semiconductor, such spin disorder, however, does not appear. Our study compares the electron excitation spectra obtained from theoretical simulations of the correlated electron lattice with data from high-resolution photoemission. We find that an unusual row-wise antiferromagnetic spin alignment occurs that is reflected in the photoemission spectra as characteristic 'shadow bands' induced by the spin pattern. The magnetic order in a frustrated lattice of otherwise non-magnetic components emerges from longer-range electron hopping between the atoms. This finding can offer new ways of controlling magnetism on surfaces.

Spin-Filtering Rectifying and Negative Differential Resistance Behaviors in Co(dmit)2 Molecular Devices with Monatomic (C, Fe, Au) Electrodes

NASA Astrophysics Data System (ADS)

Yan, Shenlang; Long, Mengqiu; Zhang, Xiaojiao; He, Jun; Xu, Hui; Gao, Yongli

2014-09-01

Using nonequilibrium Green's functions (NEGFs) combined with the density functional theory (DFT), we study the electronic transport properties of a single molecule magnet Co(dmit)2, which is sandwiched between two monatomic chain electrodes, and the different electrode materials carbon, iron and gold, have been considered. The results show that the electrodes play a crucial role in the spin-dependent transport of the Co(dmit)2 molecular device, and some interesting phenomenon, such as perfect spin-filtering effect, rectifying and negative differential resistance (NDR) can be observed. We demonstrated that the magnetic Fe electrode can lead to high spin-flittering effect, and the different hybridization and alignment of energy levels between the molecule and the electrodes may be responsible for the rectification performance, and the distributions (delocalization or localization) of the frontier molecular orbitals under different bias result in the NDR behaviors. These characteristics could be used in the study of spin physics and the realization of nanospintronic devices.

Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Ding; Seyler, Kyle L.; Linpeng, Xiayu

The integration of magnetic material with semiconductors has been fertile ground for fundamental science as well as of great practical interest toward the seamless integration of information processing and storage. We create van der Waals heterostructures formed by an ultrathin ferromagnetic semiconductor CrI 3 and a monolayer of WSe 2. We observe unprecedented control of the spin and valley pseudospin in WSe 2, where we detect a large magnetic exchange field of nearly 13 T and rapid switching of the WSe 2 valley splitting and polarization via flipping of the CrI 3 magnetization. The WSe2 photoluminescence intensity strongly depends onmore » the relative alignment between photoexcited spins in WSe 2 and the CrI 3 magnetization, because of ultrafast spin-dependent charge hopping across the heterostructure interface. The photoluminescence detection of valley pseudospin provides a simple and sensitive method to probe the intriguing domain dynamics in the ultrathin magnet, as well as the rich spin interactions within the heterostructure.« less

Observables and microscopic entropy of higher spin black holes

NASA Astrophysics Data System (ADS)

Compère, Geoffrey; Jottar, Juan I.; Song, Wei

2013-11-01

In the context of recently proposed holographic dualities between higher spin theories in AdS3 and (1 + 1)-dimensional CFTs with symmetry algebras, we revisit the definition of higher spin black hole thermodynamics and the dictionary between bulk fields and dual CFT operators. We build a canonical formalism based on three ingredients: a gauge-invariant definition of conserved charges and chemical potentials in the presence of higher spin black holes, a canonical definition of entropy in the bulk, and a bulk-to-boundary dictionary aligned with the asymptotic symmetry algebra. We show that our canonical formalism shares the same formal structure as the so-called holomorphic formalism, but differs in the definition of charges and chemical potentials and in the bulk-to-boundary dictionary. Most importantly, we show that it admits a consistent CFT interpretation. We discuss the spin-2 and spin-3 cases in detail and generalize our construction to theories based on the hs[ λ] algebra, and on the sl( N,[InlineMediaObject not available: see fulltext.]) algebra for any choice of sl(2 ,[InlineMediaObject not available: see fulltext.]) embedding.

Origin of the magnetoresistance in oxide tunnel junctions determined through electric polarization control of the interface

DOE PAGES

Inoue, Hisashi; Swartz, Adrian G.; Harmon, Nicholas J.; ...

2015-11-11

The observed magnetoresistance (MR) in three-terminal (3T) ferromagnet-nonmagnet (FM-NM) tunnel junctions has historically been assigned to ensemble dephasing (Hanle effect) of a spin accumulation, thus offering a powerful approach for characterizing the spin lifetime of candidate materials for spintronics applications. However, due to crucial discrepancies of the extracted spin parameters with known materials properties, this interpretation has come under intense scrutiny. By employing epitaxial artificial dipoles as the tunnel barrier in oxide heterostructures, the band alignments between the FM and NM channels can be controllably engineered, providing an experimental platform for testing the predictions of the various spin accumulation models.more » Using this approach, we have been able to definitively rule out spin accumulation as the origin of the 3T MR. Instead, we assign the origin of the magnetoresistance to spin-dependent hopping through defect states in the barrier, a fundamental phenomenon seen across diverse systems. In conclusion, a theoretical framework is developed that can account for the signal amplitude, linewidth, and anisotropy.« less

Electric polarization control of magnetoresistance in complex oxide heterojunctions

NASA Astrophysics Data System (ADS)

Swartz, Adrian G.; Inoue, Hisashi; Hwang, Harold Y.

2016-10-01

Lorentzian magnetoresistance (L-MR) has been widely observed in three-terminal ferromagnet-nonmagnet (FM-NM) tunnel junctions. One possible explanation for this behavior is ensemble dephasing (Hanle effect) of a spin accumulation, potentially offering a powerful approach for characterizing the spin lifetime of emerging spintronics materials. However, discrepancies between the extracted spin parameters with known materials properties has cast doubt on this interpretation for most implementations. Here, we have developed a method to control band alignments in perovskite oxide heterostructures through the use of epitaxial interface dipoles, providing a highly effective method for manipulating the Schottky barrier height and contact resistance. Using these atomically engineered heterojunctions, we are able to tune key parameters relevant to various spin accumulation models, providing an experimental platform which can test their applicability. We find that the observed L-MR is inconsistent with an interpretation of spin accumulation in either the NM material or in interface states. Rather, we consider a mechanism analogous to Coulomb blockade in quantum dots, where spin-dependent tunneling through an ensemble of interfacial defect states is controlled by local and external magnetic fields.

Configurable unitary transformations and linear logic gates using quantum memories.

PubMed

Campbell, G T; Pinel, O; Hosseini, M; Ralph, T C; Buchler, B C; Lam, P K

2014-08-08

We show that a set of optical memories can act as a configurable linear optical network operating on frequency-multiplexed optical states. Our protocol is applicable to any quantum memories that employ off-resonant Raman transitions to store optical information in atomic spins. In addition to the configurability, the protocol also offers favorable scaling with an increasing number of modes where N memories can be configured to implement arbitrary N-mode unitary operations during storage and readout. We demonstrate the versatility of this protocol by showing an example where cascaded memories are used to implement a conditional cz gate.

Ultrafast optical modification of exchange interactions in iron oxides

NASA Astrophysics Data System (ADS)

Mikhaylovskiy, R. V.; Hendry, E.; Secchi, A.; Mentink, J. H.; Eckstein, M.; Wu, A.; Pisarev, R. V.; Kruglyak, V. V.; Katsnelson, M. I.; Rasing, Th.; Kimel, A. V.

2015-09-01

Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. Here we propose a scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects with strength of 103 Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called inverse magneto-refraction, is allowed in a material of any symmetry. Its existence is corroborated by the experimental observation of terahertz emission by spin resonances optically excited in a broad class of iron oxides with a canted spin configuration. From its strength we estimate that a sub-picosecond modification of the exchange interaction by laser pulses with fluence of about 1 mJ cm-2 acts as a pulsed effective magnetic field of 0.01 Tesla.

Photoinduced dynamics to photoluminescence in Ln3+ (Ln = Ce, Pr) doped β-NaYF4 nanocrystals computed in basis of non-collinear spin DFT with spin-orbit coupling

NASA Astrophysics Data System (ADS)

Han, Yulun; Vogel, Dayton J.; Inerbaev, Talgat M.; May, P. Stanley; Berry, Mary T.; Kilin, Dmitri S.

2018-03-01

In this work, non-collinear spin DFT + U approaches with spin-orbit coupling (SOC) are applied to Ln3+ doped β-NaYF4 (Ln = Ce, Pr) nanocrystals in Vienna ab initio Simulation Package taking into account unpaired spin configurations using the Perdew-Burke-Ernzerhof functional in a plane wave basis set. The calculated absorption spectra from non-collinear spin DFT + U approaches are compared with that from spin-polarised DFT + U approaches. The spectral difference indicates the importance of spin-flip transitions of Ln3+ ions. Suite of codes for nonadiabatic dynamics has been developed for 2-component spinor orbitals. On-the-fly nonadiabatic coupling calculations provide transition probabilities facilitated by nuclear motion. Relaxation rates of electrons and holes are calculated using Redfield theory in the reduced density matrix formalism cast in the basis of non-collinear spin DFT + U with SOC. The emission spectra are calculated using the time-integrated method along the excited state trajectories based on nonadiabatic couplings.

Thermoelectric unipolar spin battery in a suspended carbon nanotube.

PubMed

Cao, Zhan; Fang, Tie-Feng; He, Wan-Xiu; Luo, Hong-Gang

2017-04-26

A quantum dot formed in a suspended carbon nanotube exposed to an external magnetic field is predicted to act as a thermoelectric unipolar spin battery which generates pure spin current. The built-in spin flip mechanism is a consequence of the spin-vibration interaction resulting from the interplay between the intrinsic spin-orbit coupling and the vibrational modes of the suspended carbon nanotube. On the other hand, utilizing thermoelectric effect, the temperature difference between the electron and the thermal bath to which the vibrational modes are coupled provides the driving force. We find that both magnitude and direction of the generated pure spin current are dependent on the strength of spin-vibration interaction, the sublevel configuration in dot, the temperatures of electron and thermal bath, and the tunneling rate between the dot and the pole. Moreover, in the linear response regime, the kinetic coefficient is non-monotonic in the temperature T and it reaches its maximum when [Formula: see text] is about one phonon energy. The existence of a strong intradot Coulomb interaction is irrelevant for our spin battery, provided that high-order cotunneling processes are suppressed.

A configuration space of homologous proteins conserving mutual information and allowing a phylogeny inference based on pair-wise Z-score probabilities.

PubMed

Bastien, Olivier; Ortet, Philippe; Roy, Sylvaine; Maréchal, Eric

2005-03-10

Popular methods to reconstruct molecular phylogenies are based on multiple sequence alignments, in which addition or removal of data may change the resulting tree topology. We have sought a representation of homologous proteins that would conserve the information of pair-wise sequence alignments, respect probabilistic properties of Z-scores (Monte Carlo methods applied to pair-wise comparisons) and be the basis for a novel method of consistent and stable phylogenetic reconstruction. We have built up a spatial representation of protein sequences using concepts from particle physics (configuration space) and respecting a frame of constraints deduced from pair-wise alignment score properties in information theory. The obtained configuration space of homologous proteins (CSHP) allows the representation of real and shuffled sequences, and thereupon an expression of the TULIP theorem for Z-score probabilities. Based on the CSHP, we propose a phylogeny reconstruction using Z-scores. Deduced trees, called TULIP trees, are consistent with multiple-alignment based trees. Furthermore, the TULIP tree reconstruction method provides a solution for some previously reported incongruent results, such as the apicomplexan enolase phylogeny. The CSHP is a unified model that conserves mutual information between proteins in the way physical models conserve energy. Applications include the reconstruction of evolutionary consistent and robust trees, the topology of which is based on a spatial representation that is not reordered after addition or removal of sequences. The CSHP and its assigned phylogenetic topology, provide a powerful and easily updated representation for massive pair-wise genome comparisons based on Z-score computations.