KamLAND bounds on solar antineutrinos and neutrino transition magnetic moments
NASA Astrophysics Data System (ADS)
Torrente-Lujan, Emilio
2003-04-01
We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar 8B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos Phi(8B) < 1.1-3.5 × 104cm-2 s-1, more than one order of magnitude smaller than existing limits, and on their appearance probability P < 0.15% (95% CL). Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field muB < 2.3 × 10-21 MeV 95% CL (for LMA (Deltam2,tan 2theta) values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case, mu leq 3.9 × 10-12 muB (95% CL) for a relatively small field B = 50 kG. For higher values of the magnetic field we obtain: mu leq 9.0 × 10-13 muB for field B = 200 kG and mu leq 2.0 × 10-13 muB for field B = 1000 kG at the same statistical significance.
Martemyanov, V.P.; Aleshin, V.I.; Tarasenko, V.G.; Tsinoev, V.G.; Sabelnikov, A.A.; Yukhimchuk, A.A.; Popov, V.V.; Baluev, V.V.; Golubkov, A.N.; Klevtsov, V.G.; Kuryakin, A.V.; Sitdikov, D.T.; Bogdanova, L.N.
2015-03-15
We present research results of the preparation project for the experimental measurement of the (anti)neutrino magnetic moment at the level of 10{sup -12} μ{sub B} using an intense tritium source of antineutrinos and a liquid helium scintillation detector. The neutrino detection in the scintillation detector is based on the scattering of neutrinos by the electrons of the helium atoms that produces fast electrons able to ionize and exciting helium atoms. The detection of the atomic radiation emitted during the relaxation process of the helium atoms and the knowledge of its parameters will allow us to conclude on the neutrino properties.
Solar antineutrinos from fluctuating magnetic fields at Kamiokande
NASA Astrophysics Data System (ADS)
Torrente-Lujan, E.
1998-11-01
We consider the effect of a strongly chaotic magnetic field at the narrow bottom of the convective zone of the Sun together with resonant matter oscillations on the production of electron Majorana antineutrinos. Even for moderate levels of noise, we show that it is possible to obtain a small but significant probability for νe-->ν¯e conversions (1-3%) at the energy range 2-10 MeV for large regions of the mixing parameter space while still satisfying present (Super)-Kamiokande antineutrino bounds and observed total rates. In the other hand it would be possible to obtain information about the solar magnetic internal field if antineutrino bounds reach the 1% level and a particle physics solution to the SNP is assumed. The mechanism presented here has the advantage of being independent of the largely unknown magnetic profile of the Sun and the intrinsic neutrino magnetic moment.
Chang, D. . Dept. of Physics and Astronomy Fermi National Accelerator Lab., Batavia, IL ); Senjanovic, G. . Dept. of Theoretical Physics)
1990-01-01
We review attempts to achieve a large neutrino magnetic moment ({mu}{sub {nu}} {le} 10{sup {minus}11}{mu}{sub B}), while keeping neutrino light or massless. The application to the solar neutrino puzzle is discussed. 24 refs.
Revisiting large neutrino magnetic moments
NASA Astrophysics Data System (ADS)
Lindner, Manfred; Radovčić, Branimir; Welter, Johannes
2017-07-01
Current experimental sensitivity on neutrino magnetic moments is many orders of magnitude above the Standard Model prediction. A potential measurement of next-generation experiments would therefore strongly request new physics beyond the Standard Model. However, large neutrino magnetic moments generically tend to induce large corrections to the neutrino masses and lead to fine-tuning. We show that in a model where neutrino masses are proportional to neutrino magnetic moments. We revisit, discuss and propose mechanisms that still provide theoretical consistent explanations for a potential measurement of large neutrino magnetic moments. We find only two viable mechanisms to realize large transition magnetic moments for Majorana neutrinos only.
New bounds on neutrino electric millicharge from limits on neutrino magnetic moment
NASA Astrophysics Data System (ADS)
Studenikin, Alexander I.
2014-07-01
Using the new limit on the neutrino anomalous magnetic moment recently obtained by the GEMMA experiment on measurements of the cross-section for the reactor antineutrino scattering on free electrons, we get, by comparing the neutrino magnetic moment and millicharge contributions to the total cross-section at the electron recoil energy threshold of the experiment, an order-of-magnitude estimation for a possible new direct upper bound on the neutrino electric millicharge \\mid q_{\
Gemma experiment: The results of neutrino magnetic moment search
NASA Astrophysics Data System (ADS)
Beda, A. G.; Brudanin, V. B.; Egorov, V. G.; Medvedev, D. V.; Pogosov, V. S.; Shevchik, E. A.; Shirchenko, M. V.; Starostin, A. S.; Zhitnikov, I. V.
2013-03-01
The result of the neutrino magnetic moment (NMM) measurement at the Kalinin Nuclear Power Plant (KNPP) with GEMMA spectrometer is presented. The antineutrino-electron scattering is investigated. A high-purity germanium (HPGe) detector with a mass of 1.5 kg placed at a distance of 13.9 m from the 3 GWth reactor core is exposed to the antineutrino flux of 2.7 × 1013 cm-2s-1. The recoil electron spectra taken in 18134 and 4487 h for the reactor ON and OFF periods are compared. The upper limit for the NMM μν < 2.9 × 10-11 μB at 90% C.L. is derived from the data processing.
Bonanos, Peter
1983-01-01
A toroidal magnet for confining a high magnetic field for use in fusion reactor research and nuclear particle detection. The magnet includes a series of conductor elements arranged about and fixed at its small major radius portion to the outer surface of a central cylindrical support each conductor element having a geometry such as to maintain the conductor elements in pure tension when a high current flows therein, and a support assembly which redistributes all or part of the tension which would otherwise arise in the small major radius portion of each coil element to the large major radius portion thereof.
Weak magnetism correction to allowed β decay for reactor antineutrino spectra
NASA Astrophysics Data System (ADS)
Wang, X. B.; Hayes, A. C.
2017-06-01
The weak magnetism correction and its uncertainty to nuclear β decay play a major role in determining the significance of the reactor neutrino anomaly. Here we examine the common approximation used for one-body weak magnetism in the calculation of fission antineutrino spectra, wherein matrix elements of the orbital angular-momentum operator contribution to the magnetic-dipole current are assumed to be proportional to those of the spin operator. Although we find this approximation invalid for a large set of nuclear structure situations, we conclude that it is valid for the relevant allowed β decays between fission fragments. In particular, the uncertainty in the fission antineutrino due to the uncertainty in the one-body weak magnetism correction is found to be less than 1%. Thus, the dominant uncertainty from weak magnetism for reactor neutrino fluxes lies in the uncertainty in the two-body meson-exchange magnetic-dipole current.
Measurement of Absolute Magnetic Moment
NASA Astrophysics Data System (ADS)
Shull, R. D.; Swartzendruber, L. J.
1998-03-01
In the past NIST has issued a number of magnetic moment and magnetic susceptibility standards. One of the most popular has been the Ni magnetic moment standard in the form a 2.38 mm diameter sphere of annealed, high-purity nickel, issued in 1978. However, the supply of all the magnetic standards has been exhausted for several years now and the equipment used for their certification no longer exists. Currently, NIST is assembling a precision absolute magnetometer closely resembling the force-based system used earlier by Candela and Mundy (G.A. Candela and R.E. Mundy, Rev. Sci. Instr. 32, 1056 (1959).), but which will have improved accuracy. This magnetometer will be used to certify a new series of magnetic standards, the first of which will be a replacement nickel sphere. A sphere has the advantage that it has uniform magnetization and a known demagnetizing factor, and approximates a point dipole. Nickel has the advantage of saturation at low field, a small temperature dependence at room temperature, and a relatively small field dependence. Other standards with smaller moments and other geometries are also being considered. These, and the current state of the equipment development will be described.
First result for the neutrino magnetic moment from measurements with the GEMMA spectrometer
NASA Astrophysics Data System (ADS)
Beda, A. G.; Brudanin, V. B.; Demidova, E. V.; Vylov, C.; Gavrilov, M. G.; Egorov, V. G.; Starostin, A. S.; Shirchenko, M. V.
2007-11-01
The first result obtained in the measurements of the neutrino magnetic moment at the Kalinin nuclear power plant with the GEMMA spectrometer is presented. A high-purity germanium detector of mass 1.5 kg placed at a distance of 13.9 m from the reactor core is used in the spectrometer. The antineutrino flux at the detector position is 2.73 × 1013 bar ν /(cm2 s). The differential method is used to select events of electromagnetic antineutrino-electron scattering. The spectra taken in the reactor-on and reactor-off modes over 6200 and 2064 h, respectively, are compared. On the basis of a data analysis, an upper limit of 5.8 × 10-11 μB was set on the neutrino magnetic moment μ ν at a 90% C.L.
First result for the neutrino magnetic moment from measurements with the GEMMA spectrometer
Beda, A. G.; Brudanin, V. B.; Demidova, E. V.; Vylov, C.; Gavrilov, M. G.; Egorov, V. G.; Starostin, A. S.; Shirchenko, M. V.
2007-11-15
The first result obtained in the measurements of the neutrino magnetic moment at the Kalinin nuclear power plant with the GEMMA spectrometer is presented. A high-purity germanium detector of mass 1.5 kg placed at a distance of 13.9 m from the reactor core is used in the spectrometer. The antineutrino flux at the detector position is 2.73 x 10{sup 13{nu}}-bar/(cm{sup 2} s). The differential method is used to select events of electromagnetic antineutrino-electron scattering. The spectra taken in the reactor-on and reactor-off modes over 6200 and 2064 h, respectively, are compared. On the basis of a data analysis, an upper limit of 5.8 x 10{sup -11} {mu}B was set on the neutrino magnetic moment {mu}{sub {nu}}at a 90% C.L.
Gemma experiment: Three years of the search for the neutrino magnetic moment
NASA Astrophysics Data System (ADS)
Beda, A. G.; Brudanin, V. B.; Egorov, V. G.; Medvedev, D. V.; Shirchenko, M. V.; Starostin, A. S.
2010-11-01
The result of the 3-year neutrino magnetic moment measurement at the Kalinin Nuclear Power Plant (KNPP) with the GEMMA spectrometer is presented. Antineutrino-electron scattering is investigated. A high-purity germanium detector of 1.5 kg placed at a distance of 13.9 m from the 3 GWth reactor core is exposed to the antineutrino flux of 2.7 × 1013 cm-2 s-1. The scattered electron spectra taken in (5184 + 6798) and (1853 + 1021) h for the reactor ON and OFF periods are compared. The upper limit for the neutrino magnetic moment μv < 3.2 × 10-11μ B at 90% CL is derived from the data processing.
Superconductivity from Emerging Magnetic Moments.
Hoshino, Shintaro; Werner, Philipp
2015-12-11
Multiorbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi-liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment-induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds.
Magnetic Moments of Excited Baryons
NASA Astrophysics Data System (ADS)
Metag, Volker
2017-01-01
In project A.3, the reaction γ p → π0γ'p has been studied using the TAPS photon spectrometer in the energy range √s= 1221-1331 MeV. Energy tagged photon beams have been produced with the Glasgow tagging spectrometer from electron beams provided by the MAMI-B accelerator. Angle and energy differential cross sections have been measured and compared to theoretical calculations. This comparison allows the magnetic moment of the Δ+ isobar to be extracted for the first time to μΔ+ = [2.7+1.3-1.0(stat)±1.5(syst)±3(theo)] μN. In an extension of the A3 project to the meson sector, the time-like transition form factor of the η meson has been measured with the Crystal Ball/TAPS detector system at MAMI-C.
Magnetic moment distribution of magnetic cataclysmic variables
NASA Technical Reports Server (NTRS)
Wu, Kinwah; Wickramasinghe, Dayal T.
1991-01-01
A simulation study is made of the relative numbers of the AM Herculis binaries and the intermediate polars as a function of the orbital period using random variables subject to suitable constraints to describe the various parameters. It is shown that the observations can be matched by a single distribution in the magnetic moment equals 0.7 +/- 0.3. For such an ensemble, the intermediate polars are distributed in the log(Porb) - log(Ps) diagram about the critical disk line but with a larger scatter than observed.
Detecting neutrino magnetic moments with conducting loops
NASA Astrophysics Data System (ADS)
Apyan, Aram; Apyan, Armen; Schmitt, Michael
2008-02-01
It is well established that neutrinos have mass, yet it is very difficult to measure those masses directly. Within the standard model of particle physics, neutrinos will have an intrinsic magnetic moment proportional to their mass. We examine the possibility of detecting the magnetic moment using a conducting loop. According to Faraday’s law of induction, a magnetic dipole passing through a conducting loop induces an electromotive force in the loop. We compute this electromotive force for neutrinos in several cases, based on a fully covariant formulation of the problem. We discuss prospects for a real experiment, as well as the possibility to test the relativistic formulation of intrinsic magnetic moments.
Magnetic moments in graphene with vacancies.
Chen, Jing-Jing; Wu, Han-Chun; Yu, Da-Peng; Liao, Zhi-Min
2014-08-07
Vacancies can induce local magnetic moments in graphene, paving the way to make magnetic functional graphene. Due to the interaction between magnetic moments and conduction carriers, the magnetotransport properties of graphene can be modulated. Here, the effects of vacancy induced magnetic moments on the electrical properties of graphene are studied via magnetotransport measurements and spin-polarized density functional theory calculations. We show by quantum Hall measurements that a sharp resonant Vπ state is introduced in the midgap region of graphene with vacancies, resulting in the local magnetic moment. The coupling between the localized Vπ state and the itinerant carrier is tuned by varying the carrier concentration, temperature, magnetic field, and vacancy density, which results in a transition between hopping transport and the Kondo effect and a transition between giant negative magnetoresistance (MR) and positive MR. This modulated magnetotransport is valuable for graphene based spintronic devices.
Exchange currents for hypernuclear magnetic moments
NASA Astrophysics Data System (ADS)
Saito, K.; Oka, M.; Suzuki, T.
1997-02-01
The meson (K and π) exchange currents for the hypernuclear magnetic moments are calculated using the effective Lagrangian method. The seagull diagram, the mesonic diagram and the Σ0-excitation diagram are considered. The Λ-N exchange magnetic moments for Λ5He and A=6 hypernuclei are calculated employing the harmonic oscillator shell model. It is found that the two-body correction is about -9% of the single particle value for Λ5He. The π exchange current, induced only in the Σ0-excitation diagram, is found to give dominant contribution for the isovector magnetic moments of hypernuclei with A = 6.
Manipulating magnetic moments by superconducting currents
NASA Astrophysics Data System (ADS)
Chudnovsky, Eugene M.
2017-03-01
We show that the interaction between a superconducting order parameter and the magnetic moment of an atomic cluster in a two-dimensional s -wave superconductor with Rashba spin-orbit coupling generates magnetic anisotropy that can be stronger or comparable to the magnetic anisotropy due to the crystal field and the shape of the cluster. Transport current through the superconductor produces the effective magnetic field acting on the cluster's magnetic moment. The direction of the effective field depends on the direction of the current, thus allowing one to manipulate the magnetic moment by the superconducting current. Due to the large density of the superconducting current this method of magnetization reversal can be more advantageous at low temperatures than the spin-transfer torque method that requires a large spin-polarized current through a normal metal.
How to Introduce the Magnetic Dipole Moment
ERIC Educational Resources Information Center
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-01-01
We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…
How to Introduce the Magnetic Dipole Moment
ERIC Educational Resources Information Center
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-01-01
We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…
Magnetic dipole moments for composite dark matter
Aranda, Alfredo; Barajas, Luis; Cembranos, Jose A.R. E-mail: luisedua@buffalo.edu
2016-03-01
We study neutral dark matter candidates with a nonzero magnetic dipole moment. We assume that they are composite states of new fermions related to the strong phase of a new gauge interaction. In particular, invoking a dark flavor symmetry, we analyze the composition structure of viable candidates depending on the assignations of hypercharge and the multiplets associated to the fundamental constituents of the extended sector. We determine the magnetic dipole moments for the neutral composite states in terms of their constituents masses.
Measurement of magnetic moment via optical transmission
NASA Astrophysics Data System (ADS)
Heidsieck, Alexandra; Schmid, Daniel; Gleich, Bernhard
2016-03-01
The magnetic moment of nanoparticles is an important property for drug targeting and related applications as well as for the simulation thereof. However, the measurement of the magnetic moment of nanoparticles, nanoparticle-virus-complexes or microspheres in solution can be difficult and often yields unsatisfying or incomparable results. To measure the magnetic moment, we designed a custom measurement device including a magnetic set-up to observe nanoparticles indirectly via light transmission in solution. We present a simple, cheap device of manageable size, which can be used in any laboratory as well as a novel evaluation method to determine the magnetic moment of nanoparticles via the change of the optical density of the particle suspension in a well-defined magnetic gradient field. In contrast to many of the established measurement methods, we are able to observe and measure the nanoparticle complexes in their natural state in the respective medium. The nanoparticles move along the magnetic gradient and thereby away from the observation point. Due to this movement, the optical density of the fluid decreases and the transmission increases over time at the measurement location. By comparing the measurement with parametric simulations, we can deduce the magnetic moment from the observed behavior.
Solar neutrino oscillations and bounds on neutrino magnetic moment and solar magnetic field
NASA Astrophysics Data System (ADS)
Akhmedov, E. Kh.; Pulido, Joa~O.
2003-01-01
If the observed deficit of solar neutrinos is due to neutrino oscillations, neutrino conversions caused by the interaction of their transition magnetic moments with the solar magnetic field (spin-flavour precession) can still be present at a subdominant level. In that case, the combined action of neutrino oscillations and spin-flavour precession can lead to a small but observable flux of electron antineutrinos coming from the sun. Non-observation of these ν¯e's could set limits on neutrino transition moment /μ and the strength and coordinate dependence of the solar magnetic field B⊥. The sensitivity of the ν¯e flux to the product μB⊥ is the strongest in the case of the vacuum oscillation (VO) solution of the solar neutrino problem; in the case of the LOW solution, it is weaker, and it is the weakest for the LMA solution. For different solutions, different characteristics of the solar magnetic field B⊥(r) are probed: for the VO solution, the ν¯e flux is determined by the integral of B⊥(r) over the solar convective zone, for LMA it is determined by the magnitude of B⊥ in the neutrino production region, and for LOW it depends on the competition between this magnitude and the derivative of B⊥(r) at the surface of the sun.
Spin and magnetic moment of 23Mg
NASA Astrophysics Data System (ADS)
Yordanov, D. T.; Bissell, M. L.; Blaum, K.; De Rydt, M.; Geppert, Ch; Krämer, J.; Kreim, K.; Kowalska, M.; Krieger, A.; Lievens, P.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Rodríguez, L. V.; Sánchez, R.; Vingerhoets, P.
2017-07-01
A negative magnetic moment of 23Mg has been determined by collinear laser spectroscopy at CERN-ISOLDE. The absolute value is in agreement with previous measurements by nuclear magnetic resonance while the sign points at high-seniority configurations. The result is consistent with shell-model predictions for nuclei with valence nucleons in the sd shell.
Determination of the Neutron Magnetic Moment
DOE R&D Accomplishments Database
Greene, G. L.; Ramsey, N. F.; Mampe, W.; Pendlebury, J. M.; Smith, K.; Dress, W. B.; Miller, P. D.; Perrin, P.
1981-06-01
The neutron magnetic moment has been measured with an improvement of a factor of 100 over the previous best measurement. Using a magnetic resonance spectrometer of the separated oscillatory field type capable of determining a resonance signal for both neutrons and protons (in flowing H{sub 2}O), we find ..mu..{sub n}/..mu..{sub p} = 0.68497935(17) (0.25 ppM). The neutron magnetic moment can also be expressed without loss of accuracy in a variety of other units.
Near-Field Magnetic Dipole Moment Analysis
NASA Technical Reports Server (NTRS)
Harris, Patrick K.
2003-01-01
This paper describes the data analysis technique used for magnetic testing at the NASA Goddard Space Flight Center (GSFC). Excellent results have been obtained using this technique to convert a spacecraft s measured magnetic field data into its respective magnetic dipole moment model. The model is most accurate with the earth s geomagnetic field cancelled in a spherical region bounded by the measurement magnetometers with a minimum radius large enough to enclose the magnetic source. Considerably enhanced spacecraft magnetic testing is offered by using this technique in conjunction with a computer-controlled magnetic field measurement system. Such a system, with real-time magnetic field display capabilities, has been incorporated into other existing magnetic measurement facilities and is also used at remote locations where transport to a magnetics test facility is impractical.
Interpreting magnetic data by integral moments
NASA Astrophysics Data System (ADS)
Tontini, F. Caratori; Pedersen, L. B.
2008-09-01
The use of the integral moments for interpreting magnetic data is based on a very elegant property of potential fields, but in the past it has not been completely exploited due to problems concerning real data. We describe a new 3-D development of previous 2-D results aimed at determining the magnetization direction, extending the calculation to second-order moments to recover the centre of mass of the magnetization distribution. The method is enhanced to reduce the effects of the regional field that often alters the first-order solutions. Moreover, we introduce an iterative correction to properly assess the errors coming from finite-size surveys or interaction with neighbouring anomalies, which are the most important causes of the failing of the method for real data. We test the method on some synthetic examples, and finally, we show the results obtained by analysing the aeromagnetic anomaly of the Monte Vulture volcano in Southern Italy.
Noncommutative magnetic moment of charged particles
Adorno, T. C.; Gitman, D. M.; Shabad, A. E.; Vassilevich, D. V.
2011-10-15
It has been argued that in noncommutative field theories, the sizes of physical objects cannot be taken smaller than an ''elementary length'' related to noncommutativity parameters. By gauge covariantly extending field equations of noncommutative U(1){sub *} theory to cover the presence of external sources, we find electric and magnetic fields produced by an extended static charge. We find that such a charge, apart from being an ordinary electric monopole, is also a magnetic dipole. By writing off the existing experimental clearance in the value of the lepton magnetic moments for the present effect, we get the bound on noncommutativity at the level of 10{sup 4} TeV.
Magnetic moment of iron in metallic environments
Fernando, G. W.; Watson, R.E.; Weinert, M.; Kocharian, A. N.; Ratnaweera, A.; Tennakone, K.
2000-01-01
Rare-earth iron nitrides are emerging as an important class of magnetic materials. In certain rare-earth iron compounds, the insertion of small atoms such as nitrogen and boron has resulted in significant changes in the magnetic properties in the form of higher Curie temperatures, enhanced magnetic moments, and stronger anisotropies. In an attempt to understand some of the above, we have focused on two nitride phases of Fe, namely Fe{sub 4}N (cubic) and Fe{sub 16}N{sub 2} (tetragonal). For the Fe{sub 16}N{sub 2} phase, the average Fe moment reported by different experimental groups varies over a wide range of values, from 2.3{mu}{sub B} to 3.5{mu}{sub B}. We will discuss some of the recent experiments and examine some related theoretical questions with regard to Fe having such an unusually large moment in a metallic environment. Employing a Hubbard-Stoner-like model in addition to local-density results, it is shown that an unusually large on-site Coulomb repulsion is necessary if one is to obtain a moment as large as 3.5{mu}{sub B}. (c) 2000 The American Physical Society.
Energy of magnetic moment of superconducting current in magnetic field
NASA Astrophysics Data System (ADS)
Gurtovoi, V. L.; Nikulov, A. V.
2015-09-01
The energy of magnetic moment of the persistent current circulating in superconducting loop in an externally produced magnetic field is not taken into account in the theory of quantization effects because of identification of the Hamiltonian with the energy. This identification misleads if, in accordance with the conservation law, the energy of a state is the energy expended for its creation. The energy of magnetic moment is deduced from a creation history of the current state in magnetic field both in the classical and quantum case. But taking this energy into account demolishes the agreement between theory and experiment. Impartial consideration of this problem discovers the contradiction both in theory and experiment.
Magnetic Moments of States in 110Sn.
NASA Astrophysics Data System (ADS)
Kumbartzki, G. J.
2016-06-01
The semi-magic Sn isotopes with Z = 50 are the subject of extensive experimental and theoretical studies. The measured B(E2) values to the 21 + states for the neutron-deficient side of the isotope chain suggest enhanced collectivity when fewer particles are available if the proton shell is not broken. Magnetic moments which are sensitive to proton and neutron contributions to the wave functions of the states could provide critical and relevant information. Magnetic moments were previously measured only for the even stable and a few neutron-rich unstable Sn isotopes. A measurement of the g factors of excited states in 110Sn using the transient field technique was performed at the 88-Inch Cyclotron at the LBNL in Berkeley. The 110Sn nuclei were produced via an α-particle transfer to 106Cd.
Dudley's dilemma: Magnetic moments in relativistic theories
NASA Astrophysics Data System (ADS)
McNeil, J. A.
1986-10-01
In 1975 L. Dudley Miller showed how the basic phenomenology of the major shell and spin-orbit splittings constrained the relativistic scalar/vector structure model to values of the potentials incompatible with the observed magnetic moments of nuclei one nucleon away from closed shell [1]. In this talk the resolution of this problem is presented from three different perspectives. First a self-consistent Landau-Migdal approach is used to define the single particle isoscalar current in infinite nuclear matter. The constraint of self-consistency provides a vector suppression factor to the single particle current which returns the current to its nonrelativistic form and resolves the problem. The same suppression factor is shown to follow as well from either a consideration of gauge invariance or (equivalently) the relativistic random phase approximation. Local density approximation calculations of isoscalar magnetic moments of nuclei one nucleon away from closed shell recover the Schmidt values, thus resolving this longstanding problem.
Nuclear magnetic moments and related sum rules
Bentz, Wolfgang; Arima, Akito
2011-05-06
We first review the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions, with emphasis on the roles of configuration mixing and meson exchange currents. Then we discuss the renormalization of the orbital g-factor in nuclei, and its relation to the E1 sum rule for photoabsorption and the M1 sum rule for the scissors mode of deformed nuclei.
Neutrino moments and the magnetic Primakoff effect
Domokos, G.; Kovesi-Domokos, S. |
1997-03-01
If different species of neutrinos possess transition magnetic moments, a conversion between species can occur in the Coulomb field of a nucleus. The conversion cross sections grow with the energy of the incident neutrino. The formalism is also applied to a new type of experiment designed to test the existence of the {open_quotes}KARMEN anomaly.{close_quote}{close_quote} {copyright} {ital 1997} {ital The American Physical Society}
Magnetic resonance signal moment determination using the Earth's magnetic field
NASA Astrophysics Data System (ADS)
Fridjonsson, E. O.; Creber, S. A.; Vrouwenvelder, J. S.; Johns, M. L.
2015-03-01
We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.
Magnetic resonance signal moment determination using the Earth's magnetic field.
Fridjonsson, E O; Creber, S A; Vrouwenvelder, J S; Johns, M L
2015-03-01
We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system. Copyright © 2015 Elsevier Inc. All rights reserved.
Development of a Thin Film Magnetic Moment Reference Material
Pappas, D. P.; Halloran, S. T.; Owings, R. R.; da Silva, F. C. S.
2008-01-01
In this paper we present the development of a magnetic moment reference material for low moment magnetic samples. We first conducted an inter-laboratory comparison to determine the most useful sample dimensions and magnetic properties for common instruments such as vibrating sample magnetometers (VSM), SQUIDs, and alternating gradient field magnetometers. The samples were fabricated and then measured using a vibrating sample magnetometer. Their magnetic moments were calibrated by tracing back to the NIST YIG sphere, SRM 2853. PMID:27096108
Maximum magnetic moment to angular momentum conjecture
NASA Astrophysics Data System (ADS)
Barrow, John D.; Gibbons, G. W.
2017-03-01
Conjectures play a central role in theoretical physics, especially those that assert an upper bound to some dimensionless ratio of physical quantities. In this paper we introduce a new such conjecture bounding the ratio of the magnetic moment to angular momentum in nature. We also discuss the current status of some old bounds on dimensionless and dimensional quantities in arbitrary spatial dimension. Our new conjecture is that the dimensionless Schuster-Wilson-Blackett number, c μ /J G1/2 , where μ is the magnetic moment and J is the angular momentum, is bounded above by a number of order unity. We verify that such a bound holds for charged rotating black holes in those theories for which exact solutions are available, including the Einstein-Maxwell theory, Kaluza-Klein theory, the Kerr-Sen black hole, and the so-called STU family of charged rotating supergravity black holes. We also discuss the current status of the maximum tension conjecture, the Dyson luminosity bound, and Thorne's hoop conjecture.
Evolving magnetic fields and the conservation of magnetic moment
NASA Astrophysics Data System (ADS)
Dobler, Wolfgang
It is shown that the magnetic moment is a conserved quantity not only in MHD, but also in general electrodynamics under certain not very restrictive conditions. The propagation of magnetic moment from a regionD with an evolving current system (e.g., due to dynamo action) is discussed for the two cases of vacuum and a conducting medium, respectively, surrounding D. In the case of vacuum, the MHD approximation no longer holds and the weak electromagnetic wave emitted from D is important, as was pointed out by Sokoloff (1997). In the case of an unbounded conducting medium, the classical definition of is generalised and is shown to propagate diffusively, undisturbed by the newly generated magnetic field.
Numerical modeling of higher order magnetic moments in UXO discrimination
Sanchez, V.; Yaoguo, L.; Nabighian, M.N.; Wright, D.L.
2008-01-01
The surface magnetic anomaly observed in unexploded ordnance (UXO) clearance is mainly dipolar, and consequently, the dipole is the only magnetic moment regularly recovered in UXO discrimination. The dipole moment contains information about the intensity of magnetization but lacks information about the shape of the target. In contrast, higher order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and to show its potential utility in UXO clearance, we present a numerical modeling study of UXO and related metallic objects. The tool for the modeling is a nonlinear integral equation describing magnetization within isolated compact objects of high susceptibility. A solution for magnetization distribution then allows us to compute the magnetic multipole moments of the object, analyze their relationships, and provide a depiction of the anomaly produced by different moments within the object. Our modeling results show the presence of significant higher order moments for more asymmetric objects, and the fields of these higher order moments are well above the noise level of magnetic gradient data. The contribution from higher order moments may provide a practical tool for improved UXO discrimination. ?? 2008 IEEE.
Ueno, Tetsuro; Sinha, Jaivardhan; Inami, Nobuhito; Takeichi, Yasuo; Mitani, Seiji; Ono, Kanta; Hayashi, Masamitsu
2015-10-12
We have studied the magnetic layer thickness dependence of the orbital magnetic moment in magnetic heterostructures to identify contributions from interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlOx and Pt/Co/Pt, which possess significant interface contribution to the perpendicular magnetic anisotropy, are studied as model systems. X-ray magnetic circular dichroism spectroscopy is used to evaluate the relative orbital moment, i.e. the ratio of the orbital to spin moments, of the magnetic elements constituting the heterostructures. We find that the relative orbital moment of Co in Pt/Co/Pt remains constant against its thickness whereas the moment increases with decreasing Co layer thickness for Pt/Co/AlOx, suggesting that a non-zero interface orbital moment exists for the latter system. For Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray absorption spectra shows that a particular oxidized Co state in Pt/Co/AlOx, absent in other heterosturctures, may give rise to the interface orbital moment in this system. These results show element specific contributions to the interface orbital magnetic moments in ultrathin magnetic heterostructures.
Ueno, Tetsuro; Sinha, Jaivardhan; Inami, Nobuhito; Takeichi, Yasuo; Mitani, Seiji; Ono, Kanta; Hayashi, Masamitsu
2015-01-01
We have studied the magnetic layer thickness dependence of the orbital magnetic moment in magnetic heterostructures to identify contributions from interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlOx and Pt/Co/Pt, which possess significant interface contribution to the perpendicular magnetic anisotropy, are studied as model systems. X-ray magnetic circular dichroism spectroscopy is used to evaluate the relative orbital moment, i.e. the ratio of the orbital to spin moments, of the magnetic elements constituting the heterostructures. We find that the relative orbital moment of Co in Pt/Co/Pt remains constant against its thickness whereas the moment increases with decreasing Co layer thickness for Pt/Co/AlOx, suggesting that a non-zero interface orbital moment exists for the latter system. For Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray absorption spectra shows that a particular oxidized Co state in Pt/Co/AlOx, absent in other heterosturctures, may give rise to the interface orbital moment in this system. These results show element specific contributions to the interface orbital magnetic moments in ultrathin magnetic heterostructures. PMID:26456454
NASA Astrophysics Data System (ADS)
Ueno, Tetsuro; Sinha, Jaivardhan; Inami, Nobuhito; Takeichi, Yasuo; Mitani, Seiji; Ono, Kanta; Hayashi, Masamitsu
2015-10-01
We have studied the magnetic layer thickness dependence of the orbital magnetic moment in magnetic heterostructures to identify contributions from interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlOx and Pt/Co/Pt, which possess significant interface contribution to the perpendicular magnetic anisotropy, are studied as model systems. X-ray magnetic circular dichroism spectroscopy is used to evaluate the relative orbital moment, i.e. the ratio of the orbital to spin moments, of the magnetic elements constituting the heterostructures. We find that the relative orbital moment of Co in Pt/Co/Pt remains constant against its thickness whereas the moment increases with decreasing Co layer thickness for Pt/Co/AlOx, suggesting that a non-zero interface orbital moment exists for the latter system. For Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray absorption spectra shows that a particular oxidized Co state in Pt/Co/AlOx, absent in other heterosturctures, may give rise to the interface orbital moment in this system. These results show element specific contributions to the interface orbital magnetic moments in ultrathin magnetic heterostructures.
Numerical modeling of magnetic moments for UXO applications
Sanchez, V.; Li, Y.; Nabighian, M.; Wright, D.
2006-01-01
The surface magnetic anomaly observed in UXO clearance is mainly dipolar and, consequently, the dipole is the only magnetic moment regularly recovered in UXO applications. The dipole moment contains information about intensity of magnetization but lacks information about shape. In contrast, higher-order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and its potential utility in UXO clearance, we present a 3D numerical modeling study for highly susceptible metallic objects. The basis for the modeling is the solution of a nonlinear integral equation describing magnetization within isolated objects. A solution for magnetization distribution then allows us to compute magnetic moments of the object, analyze their relationships, and provide a depiction of the surface anomaly produced by different moments within the object. Our modeling results show significant high-order moments for more asymmetric objects situated at depths typical of UXO burial, and suggest that the increased relative contribution to magnetic gradient data from these higher-order moments may provide a practical tool for improved UXO discrimination.
Electric-field control of magnetic moment in Pd
Obinata, Aya; Hibino, Yuki; Hayakawa, Daichi; Koyama, Tomohiro; Miwa, Kazumoto; Ono, Shimpei; Chiba, Daichi
2015-01-01
Several magnetic properties have recently become tunable with an applied electric field. Particularly, electrically controlled magnetic phase transitions and/or magnetic moments have attracted attention because they are the most fundamental parameters in ferromagnetic materials. In this study, we showed that an electric field can be used to control the magnetic moment in films made of Pd, usually a non-magnetic element. Pd ultra-thin films were deposited on ferromagnetic Pt/Co layers. In the Pd layer, a ferromagnetically ordered magnetic moment was induced by the ferromagnetic proximity effect. By applying an electric field to the ferromagnetic surface of this Pd layer, a clear change was observed in the magnetic moment, which was measured directly using a superconducting quantum interference device magnetometer. The results indicate that magnetic moments extrinsically induced in non-magnetic elements by the proximity effect, as well as an intrinsically induced magnetic moments in ferromagnetic elements, as reported previously, are electrically tunable. The results of this study suggest a new avenue for answering the fundamental question of “can an electric field make naturally non-magnetic materials ferromagnetic?” PMID:26391306
Magnetic moments of octet baryons and sea antiquark polarizations
Bartelski, Jan; Tatur, Stanislaw
2005-01-01
Using generalized Sehgal equations for magnetic moments of baryon octet and taking into account {sigma}{sup 0}-{lambda} mixing and two particle corrections to independent quark contributions we obtain very good fit using experimental values for errors of such moments. We present sum rules for quark magnetic moments ratios and for integrated spin densities ratios. Because of the SU(3) structure of our equations the results for magnetic moments of quarks and their densities depend on two additional parameters. Using information from deep inelastic scattering and baryon {beta}-decays we discuss the dependence of antiquark polarizations on introduced parameters. For some plausible values of these parameters we show that these polarizations are small if we neglect angular momenta of quarks. Our very good fit to magnetic moments of baryon octet can still be improved by using specific model for angular momentum of quarks.
Sievers, Sibylle; Braun, Kai-Felix; Eberbeck, Dietmar; Gustafsson, Stefan; Olsson, Eva; Schumacher, Hans Werner; Siegner, Uwe
2012-09-10
The quantitative measurement of the magnetization of individual magnetic nanoparticles (MNPs) using magnetic force microscopy (MFM) is described. Quantitative measurement is realized by calibration of the MFM signal using an MNP reference sample with traceably determined magnetization. A resolution of the magnetic moment of the order of 10(-18) A m(2) under ambient conditions is demonstrated, which is presently limited by the tip's magnetic moment and the noise level of the instrument. The calibration scheme can be applied to practically any magnetic force microscope and tip, thus allowing a wide range of future applications, for example in nanomagnetism and biotechnology.
Thermoinduced magnetic moment in akaganéite nanoparticles
NASA Astrophysics Data System (ADS)
Urtizberea, A.; Luis, F.; Millán, A.; Natividad, E.; Palacio, F.; Kampert, E.; Zeitler, U.
2011-06-01
It is shown that akaganéite β-FeOOH provides a good model material to experimentally investigate thermoinduced magnetic moments in antiferromagnetic nanoparticles. We characterize the magnetic properties, exchange field, anisotropy field, and antiferromagnetic susceptibility of bulk akaganéite. In the nanoparticles, we find a drastic enhancement of the antiferromagnetic susceptibility, a phenomenon first predicted by Néel. Also, we find that akaganéite nanoparticles possess a thermoinduced magnetic moment.
Relative importance of magnetic moments in UXO clearance applications
Sanchez, V.; Li, Y.; Nabighian, M.; Wright, D.
2006-01-01
Surface magnetic anomaly observed in UXO clearance is mainly dipolar and, as a result, the dipole is the only moment used regularly in UXO applications. The dipole moment contains intensity of magnetization information but lacks shape information. Unlike dipole, higher-order moments, such as quadrupole and octupole, encode asymmetry properties of magnetization distribution within buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and its potential utility in UXO clearance, we present results of a 3D numerical modeling study for highly susceptible metallic objects. The basis for modeling is the solution of a nonlinear integral equation, describing magnetization within isolated objects, allowing us to compute magnetic moments of the object, analyze their relationships, and provide a depiction of the surface anomaly produced by the different moments within the object. Our modeling results show significant high-order moments for more asymmetric objects situated at typical UXO burial depths, and suggest that the increased relative contribution to magnetic gradient data from these higher-order moments may provide a practical tool for improved UXO discrimination. ?? 2005 Society of Exploration Geophysicists.
Fits combining hyperon semileptonic decays and magnetic moments and CVC
Bohm, A.; Kielanowski, P.
1982-10-01
We have performed a test of CVC by determining the baryon charges and magnetic moments from the hyperon semileptonic data. Then CVC was applied in order to make a joint fit of all baryon semileptonic decay data and baryon magnetic moments for the spectrum generating group (SG) model as well as for the conventional (cabibbo and magnetic moments in nuclear magnetons) model. The SG model gives a very good fit with chi/sup 2//n/sub D/ = 25/20 approximately equals 21% C.L. whereas the conventional model gives a fit with chi/sup 2//n/sub D/ = 244/20.
Need for remeasurements of nuclear magnetic dipole moments
NASA Astrophysics Data System (ADS)
Gustavsson, Martin G.; Mårtensson-Pendrill, Ann-Marie
1998-11-01
The need for a reassessment of nuclear magnetic dipole moments is prompted by recent experiments on the ground-state hyperfine structure in highly charged hydrogenlike systems which are sufficiently sensitive to probe QED effects. This work gives an overview of the magnetic dipole moments for the nuclei of interest, i.e., 165Ho, 185,187Re, 203,205Tl, 207Pb, and 209Bi. It is found that the present uncertainties in the nuclear magnetic dipole moment limit the interpretation of the accurate experimental hyperfine structures for these systems.
Fractional impurity moments in two-dimensional noncollinear magnets.
Wollny, Alexander; Fritz, Lars; Vojta, Matthias
2011-09-23
We study dilute magnetic impurities and vacancies in two-dimensional frustrated magnets with noncollinear order. Taking the triangular-lattice Heisenberg model as an example, we use quasiclassical methods to determine the impurity contributions to the magnetization and susceptibility. Most importantly, each impurity moment is not quantized but receives nonuniversal screening corrections due to local relief of frustration. At finite temperatures, where bulk long-range order is absent, this implies an impurity-induced magnetic response of Curie form, with a prefactor corresponding to a fractional moment per impurity. We also discuss the behavior in an applied magnetic field, where we find a singular linear-response limit for overcompensated impurities.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; ...
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures itsmore » dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less
Lunar magnetic field - Permanent and induced dipole moments
NASA Technical Reports Server (NTRS)
Russell, C. T.; Coleman, P. J., Jr.; Schubert, G.
1974-01-01
Apollo 15 subsatellite magnetic field observations have been used to measure both the permanent and the induced lunar dipole moments. Although only an upper limit of 1.3 x 10 to the 18th gauss-cubic centimeters has been determined for the permanent dipole moment in the orbital plane, there is a significant induced dipole moment which opposes the applied field, indicating the existence of a weak lunar ionosphere.
NASA Astrophysics Data System (ADS)
Chen, R.; Todd, J.; Poonthottathil, N.; Sousa, A.; Evans, J.; MINOS/MINOS+ Collaboration
2017-09-01
Three-flavour neutrino mixing has successfully explained a wide range of neutrino oscillation data. However, results such as the electron antineutrino appearance excesses seen by LSND and MiniBooNE can be explained in terms of neutrino oscillations adding a sterile neutrino at a larger mass scale than the existing three flavour mass states. MINOS is a two-detector, long-baseline neutrino oscillation experiment that uses magnetized tracker-calorimeter detectors to measure the energy and composition of the NuMI neutrino beam. These magnetized detectors give MINOS a unique ability to be able to separate muon neutrino and antineutrino interactions. Using data taken with the NuMI beam configured in antineutrino mode, MINOS is able to search for sterile antineutrinos by looking for the disappearance of muon antineutrinos over its 734 km baseline. The sterile antineutrino signature would be seen as modulations at high energy in the charged-current muon antineutrino spectrum. We present the first MINOS results constraining 3+1 sterile antineutrino oscillations, using a combination of 3.36×1020 protons-on-target (POT) of antineutrino-enhanced beam data, and 10.56×1020 protons-on-target (POT) of neutrino-dominated beam data. These results are compared with existing constraints and future improvements to the searches are discussed.
The Determination of the Muon Magnetic Moment from Cosmic Rays
ERIC Educational Resources Information Center
Amsler, C.
1974-01-01
Describes an experiment suited for use in an advanced laboratory course in particle physics. The magnetic moment of cosmic ray muons which have some polarization is determined with an error of about five percent. (Author/GS)
Classical Aspect of the Anomalous Magnetic Moment of the Electron
NASA Astrophysics Data System (ADS)
Bordovitsyn, V. A.; Kulikova, A. V.; Savitskaya, Yu. N.
2017-03-01
Some integral effects of electromagnetic interactions, such as the electromagnetic mass and the anomalous magnetic moment of the electron, are discussed on the basis of covariant methods of classical electrodynamics.
The Determination of the Muon Magnetic Moment from Cosmic Rays
ERIC Educational Resources Information Center
Amsler, C.
1974-01-01
Describes an experiment suited for use in an advanced laboratory course in particle physics. The magnetic moment of cosmic ray muons which have some polarization is determined with an error of about five percent. (Author/GS)
Pinned orbital moments – A new contribution to magnetic anisotropy
Audehm, P.; Schmidt, M.; Brück, S.; Tietze, T.; Gräfe, J.; Macke, S.; Schütz, G.; Goering, E.
2016-01-01
Reduced dimensionality and symmetry breaking at interfaces lead to unusual local magnetic configurations, such as glassy behavior, frustration or increased anisotropy. The interface between a ferromagnet and an antiferromagnet is such an example for enhanced symmetry breaking. Here we present detailed X-ray magnetic circular dichroism and X-ray resonant magnetic reflectometry investigations on the spectroscopic nature of uncompensated pinned magnetic moments in the antiferromagnetic layer of a typical exchange bias system. Unexpectedly, the pinned moments exhibit nearly pure orbital moment character. This strong orbital pinning mechanism has not been observed so far and is not discussed in literature regarding any theory for local magnetocrystalline anisotropy energies in magnetic systems. To verify this new phenomenon we investigated the effect at different temperatures. We provide a simple model discussing the observed pure orbital moments, based on rotatable spin magnetic moments and pinned orbital moments on the same atom. This unexpected observation leads to a concept for a new type of anisotropy energy. PMID:27151436
Magnetic dipole moment estimates for an ancient lunar dynamo
NASA Technical Reports Server (NTRS)
Anderson, K. A.
1983-01-01
The four measured planetary magnetic moments combined with a recent theoretical prediction for dynamo magnetic fields suggests that no dynamo exists in the moon's interior today. For the moon to have had a magnetic moment in the past of sufficient strength to account for at least some of the lunar rock magnetism, the rotation would have been about twenty times faster than it is today and the radius of the fluid, conducting core must have been about 750 km. The argument depends on the validity of the Busse solution to the validity of the MHD problem of planetary dynamos.
Antineutrino Oscillations in the Atmospheric Sector
Himmel, Alexander I.
2011-05-01
This thesis presents measurements of the oscillations of muon antineutrinos in the atmospheric sector, where world knowledge of antineutrino oscillations lags well behind the knowledge of neutrinos, as well as a search for v_{μ} → $\\bar{v}$_{μ} transitions. Differences between neutrino and antineutrino oscillations could be a sign of physics beyond the Standard Model, including non-standard matter interactions or the violation of CPT symmetry. These measurements leverage the sign-selecting capabilities of the magnetized steel-scintillator MINOS detectors to analyze antineutrinos from the NuMI beam, both when it is in neutrino-mode and when it is in antineutrino-mode. Antineutrino oscillations are observed at |Δ$\\bar{m}$_{atm} ^{2}| = (3.36_{-0.40}^{+0.46}(stat) ± 0.06(syst)) x 10^{-3} eV^{2} and sin^{2}(2$\\bar{θ}$_{23}) = 0.860_{-0.12}^{+0.11}(stat) ± 0.01(syst). The oscillation parameters measured for antineutrinos and those measured by MINOS for neutrinos differ by a large enough margin that the chance of obtaining two values as discrepant as those observed is only 2%, assuming the two measurements arise from the same underlying mechanism, with the same parameter values. No evidence is seen for neutrino-to-antineutrino transitions.
Electron Paramagnetic Resonance of Single Magnetic Moment on a Surface
Berggren, P.; Fransson, J.
2016-01-01
We address electron spin resonance of single magnetic moments in a tunnel junction using time-dependent electric fields and spin-polarized current. We show that the tunneling current directly depends on the local magnetic moment and that the frequency of the external electric field mixes with the characteristic Larmor frequency of the local spin. The importance of the spin-polarized current induced anisotropy fields acting on the local spin moment is, moreover, demonstrated. Our proposed model thus explains the absence of an electron spin resonance for a half integer spin, in contrast with the strong signal observed for an integer spin. PMID:27156935
Right-handed neutrino magnetic moments
Aparici, Alberto; Santamaria, Arcadi; Kim, Kyungwook; Wudka, Jose
2009-07-01
We discuss the phenomenology of the most general effective Lagrangian, up to operators of dimension five, built with standard model fields and interactions including right-handed neutrinos. In particular, we find there is a dimension five electroweak moment operator of right-handed neutrinos, not discussed previously in the literature, which could have interesting phenomenological consequences.
Magnetic Moment Enhancement for Mn7 Cluster on Graphene
Liu, Xiaojie; Wang, Cai-Zhuang; Lin, Hai-Qing; Ho, Kai-Ming
2014-08-21
Mn7 cluster on graphene with different structural motifs and magnetic orders are investigated systematically by first-principles calculations. The calculations show that Mn7 on graphene prefers a two-layer motif and exhibits a ferrimagnetic coupling. The magnetic moment of the Mn7 cluster increases from 5.0 μB at its free-standing state to about 6.0 μB upon adsorption on graphene. Mn7 cluster also induces about 0.3 μB of magnetic moment in the graphene layer, leading to an overall enhancement of 1.3 μB magnetic moment for Mn7 on graphene. Detail electron transfer and bonding analysis have been carried out to investigate the origin of the magnetic enhancement.
AN ACCURATE DETERMINATION OF THE MICRON + MAGNETIC MOMENT,
magnetic resonance magnetometer . The ratio of the muon precession frequency to that of the proton in the same magnetic field is determined to be...measurements of the beat note. The magnetic field at which the precession and reference frequencies coincide is measured with reference to a proton nuclear...Using a precession technique, the magnetic moment of the positive micron meson is determined to an accuracy of 0.007%. Muons are brought to rest in
Field-enhanced magnetic moment in ellipsoidal nano-hematite
NASA Astrophysics Data System (ADS)
Malik, Vikash; Sen, Somaditya; Gelting, David R.; Gajdardziska-Josifovska, Marija; Schmidt, Marius; Guptasarma, Prasenjit
2014-04-01
Bulk hematite is a canted antiferromagnet at room temperature and displays weak magnetic coercivity above the Morin transition temperature T M ˜ 262 K. Below T M, hematite displays traditional antiferromagnetic behavior, with no net magnetic moment or magnetic hysteresis. Here, we report that ellipsoidal nanocrystals of hematite (ENH) display a significant field-enhanced magnetic moment (FEMM) upon being poled by a magnetic field. This poled moment displays a giant coercive field of nearly 6000 Oe at low temperature. Atomic resolution transmission electron microscopy indicates that the nanocrystals are single crystalline, and that the surfaces are bulk-terminated. The apical terminations include the <001> sets of planes, which are implicated in possible formation of FM-arrangements near the surface. We tentatively suggest that FEMM in ENH could also arise from uncompensated surface spins or a shell of ordered spins oriented and pinned near the surface by a magnetic field. The gradual loss of magnetic moment with increasing temperature could arise as a result of competition between surface pinning energy, and kT. The large coercive field points toward possible applications for ENH in digital magnetic recording.
Magnetic dipole moment determination by near-field analysis
NASA Technical Reports Server (NTRS)
Eichhorn, W. L.
1972-01-01
A method for determining the magnetic moment of a spacecraft from magnetic field data taken in a limited region of space close to the spacecraft. The spacecraft's magnetic field equations are derived from first principles. With measurements of this field restricted to certain points in space, the near-field equations for the spacecraft are derived. These equations are solved for the dipole moment by a least squares procedure. A method by which one can estimate the magnitude of the error in the calculations is also presented. This technique was thoroughly tested on a computer. The test program is described and evaluated, and partial results are presented.
The permanent and induced magnetic dipole moment of the moon
NASA Technical Reports Server (NTRS)
Russell, C. T.; Coleman, P. J., Jr.; Lichtenstein, B. R.; Schubert, G.
1974-01-01
Magnetic field observations with the Apollo 15 subsatellite have been used to deduce the components of both the permanent and induced lunar dipole moments in the orbital plane. The present permanent lunar magnetic dipole moment in the orbital plane is less than 1.3 times ten to the eighteenth power gauss-cu cm. Any uniformly magnetized near surface layer is therefore constrained to have a thickness-magnetization product less than 2.5 emu-cm per g. The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85. Combining this with recent measures of the ratio of the relative field strength at the ALSEP and Explorer 35 magnetometers indicates that the global lunar permeability relative to the plasma in the geomagnetic tail lobes is between 1.008 and 1.03.
Lawrence Berkeley Laboratory magnetic-moment sorting system
NASA Astrophysics Data System (ADS)
Nelson, D. H.; Barale, P. J.; Green, M. I.; Vandyke, D. A.
1985-07-01
The Magnetic Measurements Engineering Group at Lawrence Berkeley Laboratory (LBL) has designed and built, and is currently using, a Magnetic-moment Measurement and Sorting System (MMSS). The MMSS measures magnetic moments of permanent-magnet material and sorts the material according to selected criteria. The MMSS represents the latest application of the LBL General Purpose Magnetic Measurement Data Acquisition System reported on a MT-8. We describe the theoretical basis for the MMSS, the analog and digital components, and a unique method of calibrating the MMSS using only measured electrical quantities. We also discuss the measurement and sorting of permanent-magnet material to be incorporated in beam-line elements (dipoles and quadrupoles) in the Lawrence Livermore National Laboratory Advanced Test Accelerator Beam Director.
Meson Exchange Current Corrections to Magnetic Moments in Quantum Hadrodynamics
NASA Astrophysics Data System (ADS)
Morse, Thomas Marston
1990-01-01
Corrections to the magnetic moments of the non -relativistic shell model (Schmidt lines) have a long history. In the early fifties calculations of pion exchange and core polarization contributions to nuclear magnetic moments were initiated. These calculations matured by the early eighties to include other mesons and the delta isobar. Relativistic nuclear shell model calculations are relatively recent. Meson exchange and the delta isobar current contributions to the magnetic moments of the relativistic shell model have remained largely unexplored. The disagreement between the valence values of spherical relativistic mean-field models and experiment was a major problem with early (1975-1985) quantum hadrodynamics (QHD) calculations of magnetic moments. Core polarization calculations (1986-1988) have been found to resolve the large discrepancy, predicting isoscalar magnetic moments to within typically five percent of experiment. The isovector magnetic moments, however, are about twice as far from experiment with an average discrepancy of about ten percent. Several recent publications have indicated there is a need to consider isovector corrections (especially the pion) to attempt to account for these discrepancies. The pion, being the lightest of the mesons, has historically been expected to dominate isovector corrections. Because this has been found to be true in non-relativistic calculations, we calculated the pion corrections in the framework of QHD. The seagull and in-flight pion exchange current diagram corrections to the magnetic moments of eight finite nuclei (plus or minus one valence nucleon from the magic A = 16 and A = 40 doubly closed shell systems) are calculated in the framework of QHD, and compared with earlier non -relativistic calculations and experiment. It is found that the relativistic calculation of the pion isovector correction to magnetic moments is in good agreement with prior non-relativistic calculations, but unfortunately, these corrections
Magnetic moment conservation and particles acceleration in turbulence
NASA Astrophysics Data System (ADS)
Dalena, S.; Greco, A.; Matthaeus, W. H.
2010-12-01
The present work concerns the study of particle magnetic moment conservation in the presence of turbulent magnetic fields. As we know from the particle orbit theory, for slow temporal and spatial magnetic field variations(i.e. if their characteristic length and time are greater than the particle orbit diameter and the time spent by a particle to execute one orbit, respectively), the magnetic moment, defined as μ = (v^2⊥ /B) (averaged over the particle gyroperiod) is an adiabatic invariant and remains constant during particle motion. But in presence of a well developed magnetic turbulence μ can undergo rapid variations and might not be constant anymore. Of course, this fact could influence particle acceleration and could have a considerable implications in many astrophysical problems, such as coronal heating. In order to reproduce and extend some of the results obtained by Karimabadi et al. 1992, we study the interaction between ions and a single or a couple of electromagnetic waves. We varied both the wave frequency and the cosine of pitch angle at which particles are injected, in order to observe in this very simple case which is the limit for magnetic moment conservation. We also will reconsider the results of Dmitruk and Matthaeus (2006) regarding particle acceleration in turbulence, taking into account statistics of the magnetic moment (see also Lehe et al., 2010). Later we will add more waves to obtain a complete turbulent spectrum. The final aim of this research work is the understanding the behavior of particles magnetic moment during magnetic reconnection phenomena. H. Karimabadi, D. Krauss-Varban and T. Teresawa, JGR, 97, 13853, 1992. P. Dmitruk and W. H. Matthaeus, JGR, 11, A12110, 2006. R. Lehe, I. J. Parrish and E. Quataert, Astrophys. J. 707, 404, 2009.
Fluxonium-Based Artificial Molecule with a Tunable Magnetic Moment
NASA Astrophysics Data System (ADS)
Kou, A.; Smith, W. C.; Vool, U.; Brierley, R. T.; Meier, H.; Frunzio, L.; Girvin, S. M.; Glazman, L. I.; Devoret, M. H.
2017-07-01
Engineered quantum systems allow us to observe phenomena that are not easily accessible naturally. The LEGO®-like nature of superconducting circuits makes them particularly suited for building and coupling artificial atoms. Here, we introduce an artificial molecule, composed of two strongly coupled fluxonium atoms, which possesses a tunable magnetic moment. Using an applied external flux, one can tune the molecule between two regimes: one in which the ground-excited state manifold has a magnetic dipole moment and one in which the ground-excited state manifold has only a magnetic quadrupole moment. By varying the applied external flux, we find the coherence of the molecule to be limited by local flux noise. The ability to engineer and control artificial molecules paves the way for building more complex circuits for quantum simulation and protected qubits.
Ratio of isoscalar to isovector core polarization for magnetic moments
Zamick, L.; Sharon, Y. Y.; Robinson, S. J. Q.
2010-12-15
In calculations of isoscalar magnetic moments of odd-odd N=Z nuclei, it was found that, for medium- to heavy-mass nuclei, large-scale shell-model calculations yielded results that were very close to those obtained with the much simpler single-j shell model. To understand this, we compare isoscalar and isovector core-polarization configuration-mixing contributions to the magnetic moments of mirror pairs in first-order perturbation theory, using a spin-dependent {delta} interaction. We fit the strength of the {delta} interaction by looking at isovector and isoscalar mirror pairs. We then use the same interaction to calculate corrections due to first-order core polarization of the magnetic moments of odd-odd nuclei.
Variational master equation approach to dynamics of magnetic moments
NASA Astrophysics Data System (ADS)
Bogolubov, N. N.; Soldatov, A. V.
2016-07-01
Non-equilibrium properties of a model system comprised of a subsystem of magnetic moments strongly coupled to a selected Bose field mode and weakly coupled to a heat bath made of a plurality of Bose field modes was studied on the basis of non-equilibrium master equation approach combined with the approximating Hamiltonian method. A variational master equation derived within this approach is tractable numerically and can be readily used to derive a set of ordinary differential equations for various relevant physical variables belonging to the subsystem of magnetic moments. Upon further analysis of the thus obtained variational master equation, an influence of the macroscopic filling of the selected Bose field mode at low enough temperatures on the relaxation dynamics of magnetic moments was revealed.
Effective particle magnetic moment of multi-core particles
NASA Astrophysics Data System (ADS)
Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian; Wetterskog, Erik; Svedlindh, Peter; Lak, Aidin; Ludwig, Frank; van IJzendoorn, Leo J.; Westphal, Fritz; Grüttner, Cordula; Gehrke, Nicole; Gustafsson, Stefan; Olsson, Eva; Johansson, Christer
2015-04-01
In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems - BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.
Superconducting Gap Spectroscopy Using the Nonlinear Magnetic Moment
NASA Astrophysics Data System (ADS)
Žutić, Igor; Valls, Oriol T.
1997-03-01
We present results for the nonlinear current response of High Temperature Superconductors in an applied magnetic field. We examine the angular dependence of the nonlinear magnetic moment in the Meissner regime, and show that this quantity can serve as a high quality bulk probe to determine in detail the position of the nodes of the pairing state. The specific angular dependences of the magnetic moment for several of the proposed pairing states will be presented. Effects of the a-b plane anisotropy in the penetration depth and the sample shape ( I. Žutić, O. T. Valls Phys. Rev. B 54, 15500 (1996)) are included. In addition to the applied static magnetic field, we also consider an harmonically varying magnetic field. In the latter case the nonlinear superconducting response produces harmonics with higher frequency. We will compare our predictions with the most recent experimental data.
The Magnetic Moments of the Proton and the Antiproton
NASA Astrophysics Data System (ADS)
Ulmer, Stefan; Smorra, Christian
A comparison of the magnetic moments of the proton and the antiproton provides a sensitive test of matter-antimatter symmetry. While the magnetic moment of the proton is known with a relative precision of 10^{-8}, that of the antiproton is only known with moderate accuracy. Important progress towards a high-precision measurement of the particle's magnetic moment was reported in 2011 by a group at Mainz when spin transitions of a single proton stored in a cryogenic Penning trap were observed. To resolve the single-proton spin flips, the so-called 'continuous Stern-Gerlach effect' was utilized. Using this technique, the proton magnetic moment was measured by two groups at Mainz and Harvard with relative precisions of 8.9× 10^{-6} and 2.5× 10^{-6}, respectively. Currently, two collaborations at the CERN antiproton decelerator (AD)—a part of ATRAP and BASE—are pushing their efforts to apply the methods developed for the proton to measure the magnetic moment of the antiproton. Very recently, DiSciacca et al. reported on a measurement of the antiproton's magnetic moment with a relative precision of 4.4 ppm, which is a improvement of the formerly best value by about a factor of 680. Using the so-called double Penning trap technique, both collaborations aim for a precision measurement at the level of at least 10^{-9} in future experiments, which would provide a highly sensitive test of the CPT symmetry using baryons.
Cooper pairsʼ magnetic moment in MCFL color superconductivity
NASA Astrophysics Data System (ADS)
Feng, Bo; Ferrer, Efrain J.; de la Incera, Vivian
2011-12-01
We investigate the effect of the alignment of the magnetic moments of Cooper pairs of charged quarks that form at high density in three-flavor quark matter. The high-density phase of this matter in the presence of a magnetic field is known to be the Magnetic Color-Flavor-Locked (MCFL) phase of color superconductivity. We derive the Fierz identities of the theory and show how the explicit breaking of the rotational symmetry by the uniform magnetic field opens new channels of interactions and allows the formation of a new diquark condensate. The new order parameter is a spin-1 condensate proportional to the component in the field direction of the average magnetic moment of the pairs of charged quarks. The magnitude of the spin-1 condensate becomes comparable to the larger of the two scalar gaps in the region of large fields. The existence of the spin-1 condensate is unavoidable, as in the presence of a magnetic field there is no solution of the gap equations with nonzero scalar gaps and zero magnetic moment condensate. This is consistent with the fact that the extra condensate does not break any symmetry that has not already been broken by the known MCFL gaps. The spin-1 condensate enhances the condensation energy of pairs formed by charged quarks and the magnetization of the system. We discuss the possible consequences of the new order parameter on the issue of the chromomagnetic instability that appears in color superconductivity at moderate density.
Magnetic Moment of Proton Drip-Line Nucleus (9)C
NASA Technical Reports Server (NTRS)
Matsuta, K.; Fukuda, M.; Tanigaki, M.; Minamisono, T.; Nojiri, Y.; Mihara, M.; Onishi, T.; Yamaguchi, T.; Harada, A.; Sasaki, M.
1994-01-01
The magnetic moment of the proton drip-line nucleus C-9(I(sup (pi)) = 3/2, T(sub 1/2) = 126 ms) has been measured for the first time, using the beta-NMR detection technique with polarized radioactive beams. The measure value for the magnetic moment is 1mu(C-9)! = 1.3914 +/- 0.0005 (mu)N. The deduced spin expectation value
Photoproduction of the rho meson and its magnetic moments
Kaneko, Hiromi; Hosaka, Atsushi; Scholten, Olaf
2011-10-21
We study photoproduction of {rho} meson in a model of hidden local symmetry. We introduce the {rho} meson on a hidden gauge boson and phenomenological {rho} meson-nucleon Lagrangian is constructed respecting chiral symmetry. It turns out that the {sigma}-exchange interaction plays an important role in neutral {rho} meson photoproduction to reproduce the experimental cross sections. In charged {rho} meson photoproduction, the model takes into account the {rho} meson magnetic moments from the three-point vertex in the kinetic terms. We show that the magnetic moment of the charged {rho} meson has a significant effect on the total cross sections in proportion to the photon energies.
A proposal for the origin of the anomalous magnetic moment
NASA Astrophysics Data System (ADS)
Novello, M.; Bittencourt, E.
2014-05-01
We investigate a new form of contribution for the anomalous magnetic moment of all particles. This common origin is displayed in the framework of a recent treatment of electrodynamics that is based on the introduction of an electromagnetic metric which has no gravitational character. This effective metric constitutes a universal pure electromagnetic process perceived by all bodies, charged or not charged. As a consequence, it yields a complementary explanation for the existence of anomalous magnetic moment for charged particles and even for noncharged ones like neutrinos.
On the Theoretical Uncertainties in the Muon Anomalous Magnetic Moment
Melnikov, Kirill
2001-07-25
I present a fairly detailed discussion of various contributions to the anomalous magnetic moment of the muon a{sub {mu}}. I try to give an unbiased evaluation of the validity of the SM prediction for this quantity and to point out some delicate issues involved in its calculation. I conclude that the theory uncertainties in the SM prediction for the muon anomalous magnetic moment are underestimated and a great deal of work will be required to reduce these uncertainties to the level required by experiment.
Magnetic moments of negative parity baryons in QCD
NASA Astrophysics Data System (ADS)
Aliev, T. M.; Savcı, M.
2014-03-01
Using the most general form of the interpolating current for the octet baryons, the magnetic moments of the negative-parity baryons are calculated within the light-cone sum rules. The contributions coming from diagonal transitions of the positive-parity baryons and also from a nondiagonal transition between positive- and negative-parity baryons are eliminated by considering the combinations of different sum rules corresponding to the different Lorentz structures. A comparison of our results on magnetic moments of the negative-parity baryons with the other approaches existing in the literature is presented.
Magnetic moments of JP=3/2- baryons in QCD
NASA Astrophysics Data System (ADS)
Aliev, T. M.; Savcı, M.
2014-12-01
The magnetic moments of the low lying, negative parity, spin-3 /2 baryons, including the Λ* baryon, are calculated within the light cone QCD sum rules method. The contributions coming from the positive parity, spin-3 /2 baryons, as well as from the positive and negative parity spin-1 /2 baryons are eliminated by constructing combinations of various invariant amplitudes corresponding to the coefficients of the different Lorentz structures. We also present the results for the magnetic moments of the positive parity, spin-3 /2 baryons.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and ^{3}He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_{π} ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of ^{3}He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, μ_{3H} ~ μ_{p}. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.
A magnetometer for estimating the magnetic moment of magnetic micro-particles.
Punyabrahma, P; Jayanth, G R
2017-01-01
Magnetic micro-particles find a variety of applications as actuators at the micrometer and nanometer length scales. While the actuation gain is directly proportional to their magnetic moment, there are relatively few technologies available to estimate the magnetic moment of individual magnetic particles. This paper proposes a magnetometer for direct measurement of the magnetic moment of ferromagnetic micro-particles. The magnetometer comprises a novel micro-scale force sensor capable of interacting with magnetic particles and deflecting in response to the force of interaction. It also comprises a high-resolution measurement system, a source of magnetizing field, and a nanopositioner. The principle of operation of the magnetometer is discussed and is shown to enable the determination of the magnetic moment even of the buried magnetic particles, and those of irregular geometry. Subsequently, the force sensor, the measurement system, and the magnetic field sources are designed, fabricated, and calibrated. Finally, the magnetometer is employed to measure the magnetic moments of both fixed and untethered permanent magnetic particles and also of a fixed soft ferromagnetic particle. In all cases, the estimated magnetic moment is shown to agree with the theoretical estimate with an average error of about 16%.
A magnetometer for estimating the magnetic moment of magnetic micro-particles
NASA Astrophysics Data System (ADS)
Punyabrahma, P.; Jayanth, G. R.
2017-01-01
Magnetic micro-particles find a variety of applications as actuators at the micrometer and nanometer length scales. While the actuation gain is directly proportional to their magnetic moment, there are relatively few technologies available to estimate the magnetic moment of individual magnetic particles. This paper proposes a magnetometer for direct measurement of the magnetic moment of ferromagnetic micro-particles. The magnetometer comprises a novel micro-scale force sensor capable of interacting with magnetic particles and deflecting in response to the force of interaction. It also comprises a high-resolution measurement system, a source of magnetizing field, and a nanopositioner. The principle of operation of the magnetometer is discussed and is shown to enable the determination of the magnetic moment even of the buried magnetic particles, and those of irregular geometry. Subsequently, the force sensor, the measurement system, and the magnetic field sources are designed, fabricated, and calibrated. Finally, the magnetometer is employed to measure the magnetic moments of both fixed and untethered permanent magnetic particles and also of a fixed soft ferromagnetic particle. In all cases, the estimated magnetic moment is shown to agree with the theoretical estimate with an average error of about 16%.
Photospheric Magnetic Diffusion by Measuring Moments of Active Regions
NASA Astrophysics Data System (ADS)
Engell, Alexander; Longcope, D.
2013-07-01
Photospheric magnetic surface diffusion is an important constraint for the solar dynamo. The HMI Active Region Patches (HARPs) program automatically identify all magnetic regions above a certain flux. In our study we measure the moments of ARs that are no longer actively emerging and can thereby give us good statistical constraints on photospheric diffusion. We also present the diffusion properties as a function of latitude, flux density, and single polarity (leading or following) within each HARP.
Birefringence Determination of Magnetic Moments of Magnetotactic Bacteria
Rosenblatt, Charles; de Araujo, F. Flavio Torres; Frankel, Richard B.
1982-01-01
A birefringence technique is used to determine the average magnetic moments <μ> of magnetotactic bacteria in culture. Differences in <μ> are noted between live and dead bacteria, as well as between normal density and high density samples of live bacteria. ImagesFIGURE 1 PMID:6814546
Giant magnetic moment at open ends of multiwalled carbon nanotubes
NASA Astrophysics Data System (ADS)
Wang, Gang; Chen, Min-Jiang; Yu, Fang; Xue, Lei-Jiang; Deng, Ya; Zhang, Jian; Qi, Xiao-Ying; Gao, Yan; Chu, Wei-Guo; Liu, Guang-Tong; Yang, Hai-Fang; Gu, Chang-Zhi; Sun, Lian-Feng
2015-01-01
The attractions of cantilevers made of multiwalled carbon nanotubes (MWNTs) and secured on one end are studied in the non-uniform magnetic field of a permanent magnet. Under an optical microscope, the positions and the corresponding deflections of the original cantilevers (with iron catalytic nanoparticles at the free end) and corresponding cut-off cantilevers (the free ends consisting of open ends of MWNTs) are studied. Both kinds of CNT cantilevers are found to be attracted by the magnet, and the point of application of force is proven to be at the tip of the cantilever. By measuring and comparing deflections between these two kinds of cantilevers, the magnetic moment at the open ends of the CNTs can be quantified. Due to the unexpectedly high value of the magnetic moment at the open ends of carbon nanotubes, it is called giant magnetic moment, and its possible mechanisms are proposed and discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 10774032 and 51472057) and the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. Y2010031).
Classical orbital magnetic moment in a dissipative stochastic system
NASA Astrophysics Data System (ADS)
Kumar, N.
2012-01-01
We present an analytical treatment of the dissipative-stochastic dynamics of a charged classical particle confined biharmonically in a plane with a uniform static magnetic field directed perpendicular to the plane. The stochastic dynamics gives a steady state in the long-time limit. We have examined the orbital magnetic effect of introducing a parametrized deviation (η-1) from the second fluctuation-dissipation relation that connects the driving noise and the frictional memory kernel in the standard Langevin dynamics. The main result obtained here is that the moving charged particle generates a finite orbital magnetic moment in the steady state, and that the moment shows a crossover from para- to diamagnetic sign as the parameter η is varied. It is zero for η=1 that makes the steady state correspond to equilibrium, as it should. The magnitude of the orbital magnetic moment turns out to be a nonmonotonic function of the applied magnetic field, tending to zero in the limit of an infinitely large as well as an infinitesimally small magnetic field. These results are discussed in the context of the classic Bohr-van Leeuwen theorem on the absence of classical orbital diamagnetism. Possible realization is also briefly discussed.
Constraining the neutrino magnetic dipole moment from white dwarf pulsations
Córsico, A.H.; Althaus, L.G.; García-Berro, E. E-mail: althaus@fcaglp.unlp.edu.ar E-mail: kepler@if.ufrgs.br
2014-08-01
Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μ{sub ν}) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pidot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pidot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μ{sub ν} ∼< 10{sup -11} μ{sub B}. This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound.
Constraining the neutrino magnetic dipole moment from white dwarf pulsations
NASA Astrophysics Data System (ADS)
Córsico, A. H.; Althaus, L. G.; Miller Bertolami, M. M.; Kepler, S. O.; García-Berro, E.
2014-08-01
Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μν) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pi dot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pi dot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μν lesssim 10-11 μB. This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound.
Baryon magnetic moments and baryon masses in QCD
NASA Astrophysics Data System (ADS)
Ha, Phuoc Dai
1999-11-01
This thesis is concerned with baryon structure in QCD, mainly the theory of the baryon magnetic moments and baryon masses. I derived the usual quark model for the moments with corrections for the binding of the quarks analytically in a quenched Wilson-loop approach to QCD, and have successfully built a loop expansion approach to get beyond the quenched approximation. This theory of the baryon magnetic moments (octet, decuplet and transition) uses only three parameters, the effective quark moments μu, μ s, and a wave function parameter λ which is constrained by theory and experiment. It fits the moments much better than other models. I extend the loop expansion approach to the study of the baryon masses from the quark model, and find that the masses in the baryon octet and decuplet are very well described. The reliability of the form factors used to describe to compositeness of the hadrons is discussed. A detailed study of the structure of the loop corrections show that they contain terms with the tree level structure of the baryon masses, and a left over component coming from the quark spin-spin exchange interaction that is responsible for the violations of the Gell-Mann - Okubo mass relations.
Magnetic charge and moment dynamics in artificial kagome spin ice
NASA Astrophysics Data System (ADS)
Farhan, A.; Derlet, P. M.; Anghinolfi, L.; Kleibert, A.; Heyderman, L. J.
2017-08-01
Spin ice materials represent an intriguing class of frustrated magnetic systems which, through their geometry, admit an exponential number of approximately degenerate configurations. In this paper, the relaxation properties of a thermally active artificial kagome spin ice system are studied. Through application of an external magnetic field, an out-of-equilibrium vertex charge ordered configuration is selected and relaxed under approximate zero-field conditions. Using x-ray photo-emission electron microscopy, the magnetic moment and vertex charge degrees of freedom are followed in space and time, revealing different dynamics to that seen in past athermal equilibration protocols, and a relaxation which is well described by a point-dipolar model system. Furthermore the charge correlations are found to relax with a time scale several times smaller than that of the moment correlations.
EM induction experiment to determine the moment of a magnet
NASA Astrophysics Data System (ADS)
Najiya Maryam, K. M.
2014-05-01
If we drop a magnet through a coil, an emf is induced in the coil according to Faraday’s law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets. Mathematical expressions are derived for both. Knowing this equation, experiments to calculate the moment of a magnet can be devised. If we use a long conducting tube instead of a simple coil in this experiment, it can even help in measuring the eddy current damping coefficient k.
Some comments on the magnetic moments used in REFe2 exchange spring micro-magnetic simulations.
Bowden, G J; Buckingham, A R; Stenning, G B G; de Groot, P A J
2010-07-28
The current status of magnetic moments used in micro-magnetic modelling of the Laves phase rare earth iron REFe(2) inter-metallic compounds is reviewed. In particular, it is argued that both the neutron scattering results and band structure calculations provide little support for the long-held view that the Fe 3d moments are constant across the REFe(2) series, and for the oft-used rule of thumb that the (57)Fe hyperfine field is proportional to the Fe magnetic moment. Nevertheless, it is argued that it is acceptable to employ a simple ferrimagnetic model, in which the free-ion moment is ascribed to the RE ion and a moment of μ(d) = μ(3d) + μ(5d)≈1.5 µ(B) is used for the combined Fe(3d) and Fe-driven RE(5d) moments.
Nonadiabatic behavior of the magnetic moment of a charged particle in a dipole magnetic field
NASA Technical Reports Server (NTRS)
Murakami, Sadayoshi; Sato, Tetsuya; Hasegawa, Akira
1990-01-01
This paper investigates the dynamic behavior of the magnetic moment of a particle confined in a magnetic dipole field in the presence of a low-frequency electrostatic wave. It is shown that there exist two kinds of resonances (the bounce-E x B drift resonance and the wave-drift resonance) by which the adiabaticity of the magnetic moment is broken. The unstable conditions obtained by theoretical considerations showed good agreement with the numerical results.
Neutrino magnetic moment, CP violation, and flavor oscillations in matter
NASA Astrophysics Data System (ADS)
Pehlivan, Y.; Balantekin, A. B.; Kajino, Toshitaka
2014-09-01
We consider collective oscillations of neutrinos, which are emergent nonlinear flavor evolution phenomena instigated by neutrino-neutrino interactions in astrophysical environments with sufficiently high neutrino densities. We investigate the symmetries of the problem in the full three-flavor mixing scheme and in the exact many-body formulation by including the effects of CP violation and the neutrino magnetic moment. We show that, similar to the two-flavor scheme, several dynamical symmetries exist for three flavors in the single-angle approximation if the net electron background in the environment and the effects of the neutrino magnetic moment are negligible. Moreover, we show that these dynamical symmetries are present even when the CP symmetry is violated in neutrino oscillations. We explicitly write down the constants of motion through which these dynamical symmetries manifest themselves in terms of the generators of the SU(3) flavor transformations. We also show that the effects due to the CP-violating Dirac phase factor out of the many-body evolution operator and evolve independently of nonlinear flavor transformations if neutrino electromagnetic interactions are ignored. In the presence of a strong magnetic field, CP-violating effects can still be considered independently provided that an effective definition for the neutrino magnetic moment is used.
The solar neutrino problem and the neutrino magnetic moment
NASA Astrophysics Data System (ADS)
Pulido, João
1992-02-01
The physics of the proposed solution to the solar neutrino puzzle based on the neutrino magnetic moment is reviewed. The magnetic moment transition mechanism from active to sterile neutrinos can be either resonant or non-resonant and its kinship to matter enhanced oscillations is shown. The transition probability in the adiabatic approximation is calculated and the limits to adiabaticity are discussed. The full probability incorporating both the adiabatic and non-adiabatic regimes is derived using the Landau-Zener approximation for the non-adiabatic regimes. The available experimental data from the three existing solar neutrino experiments (Davis, Kamiokande II and SAGE) are compared with the results of the theory. From this comparison one can predict for the flavour square mass difference Δ2m21 = (0.5-1.5) x 10-8eV2 and for the magnetic moment μ > (6-7) × 10-12 μB. The uncertainties in the solar magnetic field are considerable and the ansatz used takes a value of 10 5 G along the solar core and the radiation zone, decreasing then linearly along the convection zone. A change in B by one or two orders of magnitude has the main effect of modifying the lower bound on μ by the same proportion, while leaving Δ2m21 practically unaltered. An anticorrelation between neutrino flux and solar activity, although consistent with the theory, cannot be clearly predicted.
Magnetic Shielding Studies for Electric Dipole Moment Experiments
NASA Astrophysics Data System (ADS)
Gould, Harvey; Feinberg, B.
2014-09-01
Electric dipole moment experiments are necessarily sensitive to magnetic fields and hence require effective magnetic shielding. In testing the shielding factor of single-layer Permalloy (Carpenter HyMu ``80'' ®) cylinders, we find time-dependent effects lasting tens of minutes to thousands of minutes when a static magnetic field is applied to a Permalloy cylinder that has been demagnetized in a region of near-zero field. A decrease in the magnetic field, measured at the center of the cylinder, of about 20 percent is observed for applied fields ranging from 0.5 A/m to 16 A/m. The latter applied field is comparable to the Earth's magnetic field. Effects that resemble these have been seen in other ferromagnetic materials.
Detection of Magnetic Moment Distribution in URu2Si2
NASA Astrophysics Data System (ADS)
Hanzawa, Katsurou
2017-04-01
We reexamine the octupole order model, for the hidden order (HO) in URu2Si2, based on the Γ1-Γ5 (singlet-doublet) crystalline-electric-field level scheme for 5f2 of U4+ ions. As the predominant octupole moments of Eu symmetry consistent with the characteristics of the HO, not only the type of (x(y2 - z2),y(z2 - x2)) proposed previously but also that of (x(5x2 - 3r2),y(5y2 - 3r2)) should be considered. We discuss that the magnetic moment distribution caused by these octupole orders can be verified experimentally by means of neutron diffraction, X-ray magnetic diffraction, and resonant X-ray scattering.
Top Quark Amplitudes with an Anomolous Magnetic Moment
Larkoski, Andrew J.; Peskin, Michael E.; /SLAC
2011-06-23
The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with t{bar t} and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.
Top quark amplitudes with an anomalous magnetic moment
NASA Astrophysics Data System (ADS)
Larkoski, Andrew J.; Peskin, Michael E.
2011-02-01
The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with tt¯ and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.
The opposite induced magnetic moment in narrow zigzag graphene nanoribbons
NASA Astrophysics Data System (ADS)
Liu, Hong; Hu, Bian; Liu, Na
2016-11-01
Based on the analysis of band structure and edge states on zigzag graphene nanoribbons (ZGNRs), we can study theoretically the origination of two minimal quantum conductance. At the two energy points - 0.20 eV and 0.15 eV corresponding to the two dips of quantum conductance, the spin-polarized quantum conductance is about 45%. Furthermore, the two types of edge-localized carriers in the opposite transport directions along the two opposite edge sides form the quantum internal loop current, which can generate one big magnetic moment. At these two energy points - 0.17 eV and 0.15 eV the two induced magnetic moments are in opposite signals.
Limits on the neutrino magnetic moment from the MUNU experiment
NASA Astrophysics Data System (ADS)
Munu Collaboration; Daraktchieva, Z.; Lamblin, J.; Link, O.; Amsler, C.; Avenier, M.; Broggini, C.; Busto, J.; Cerna, C.; Gervasio, G.; Jeanneret, P.; Jonkmans, G.; Koang, D. H.; Lebrun, D.; Ould-Saada, F.; Puglierin, G.; Stutz, A.; Tadsen, A.; Vuilleumier, J.-L.
2003-07-01
The MUNU experiment was carried out at the Bugey nuclear power reactor. The aim was the study of ν¯ee- elastic scattering at low energy. The recoil electrons were recorded in a gas time projection chamber, immersed in a tank filled with liquid scintillator serving as veto detector, suppressing in particular Compton electrons. The measured electron recoil spectrum is presented. Upper limits on the neutrino magnetic moment were derived and are discussed.
A moment equation description of magnetic reversals in the earth
Robbins, K. A.
1976-01-01
Low order moments of the alpha dynamo equations in a geophysical regime are related to the dependent variables in a reversing disk dynamo. The link suggests that nonperiodic reversal is an intrinsic feature of the alpha dynamo equations provided the forcing is vigorous and the toroidal and poloidal magnetic fields are sufficiently out of phase. The nonuniformities in reversal frequency are then attributable to subcritical instability. PMID:16592371
Emergent magnetic moments produced by self-damage in plutonium.
McCall, S K; Fluss, M J; Chung, B W; McElfresh, M W; Jackson, D D; Chapline, G F
2006-11-14
Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5f electron orbitals. Despite the importance of the 5f electrons in defining the structure and physical properties, there is no experimental evidence that these electrons localize to form magnetic moments in pure Pu. Instead, a large temperature-independent Pauli susceptibility indicates that they form narrow conduction bands. Radiation damage from the alpha-particle decay of Pu creates numerous defects in the crystal structure, which produce a significant temperature-dependent magnetic susceptibility, chi(T), in both alpha-Pu and delta-Pu (stabilized by 4.3 atomic percent Ga). This effect can be removed by thermal annealing above room temperature. By contrast, below 35 K the radiation damage is frozen in place, permitting the evolution in chi(T) with increasing damage to be studied systematically. This result leads to a two-component model consisting of a Curie-Weiss term and a short-ranged interaction term consistent with disorder-induced local moment models. Thus, it is shown that self-damage creates localized magnetic moments in previously nonmagnetic plutonium.
Emergent magnetic moments produced by self-damage in plutonium
McCall, S. K.; Fluss, M. J.; Chung, B. W.; McElfresh, M. W.; Jackson, D. D.; Chapline, G. F.
2006-01-01
Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5f electron orbitals. Despite the importance of the 5f electrons in defining the structure and physical properties, there is no experimental evidence that these electrons localize to form magnetic moments in pure Pu. Instead, a large temperature-independent Pauli susceptibility indicates that they form narrow conduction bands. Radiation damage from the α-particle decay of Pu creates numerous defects in the crystal structure, which produce a significant temperature-dependent magnetic susceptibility, χ(T), in both α-Pu and δ-Pu (stabilized by 4.3 atomic percent Ga). This effect can be removed by thermal annealing above room temperature. By contrast, below 35 K the radiation damage is frozen in place, permitting the evolution in χ(T) with increasing damage to be studied systematically. This result leads to a two-component model consisting of a Curie–Weiss term and a short-ranged interaction term consistent with disorder-induced local moment models. Thus, it is shown that self-damage creates localized magnetic moments in previously nonmagnetic plutonium. PMID:17088554
Nuclear Magnetic Moment of the {sup 57}Cu Ground State
Minamisono, K.; Mertzimekis, T.J.; Pereira, J.; Mantica, P.F.; Pinter, J.S.; Stoker, J.B.; Tomlin, B.E.; Weerasiri, R.R.; Davies, A.D.; Hass, M.; Rogers, W.F.
2006-03-17
The nuclear magnetic moment of the ground state of {sup 57}Cu(I{sup {pi}}=3/2{sup -},T{sub 1/2}=196.3 ms) has been measured to be vertical bar {mu}({sup 57}Cu) vertical bar =(2.00{+-}0.05){mu}{sub N} using the {beta}-NMR technique. Together with the known magnetic moment of the mirror partner {sup 57}Ni, the spin expectation value was extracted as <{sigma}{sigma}{sub z}>=-0.78{+-}0.13. This is the heaviest isospin T=1/2 mirror pair above the {sup 40}Ca region for which both ground state magnetic moments have been determined. The discrepancy between the present results and shell-model calculations in the full fp shell giving {mu}({sup 57}Cu){approx}2.4{mu}{sub N} and <{sigma}{sigma}{sub z}>{approx}0.5 implies significant shell breaking at {sup 56}Ni with the neutron number N=28.
Magnetic moments and non-Fermi-liquid behavior in quasicrystals
NASA Astrophysics Data System (ADS)
Andrade, Eric
Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15, we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures, leading to a power-law distribution of Kondo temperatures, accompanied by a non-Fermi-liquid behavior, in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. This work was supported by FAPESP (Brazil) Grant No. 2013/00681-8.
Magnetic moments and angular momenta of stars and planets
NASA Technical Reports Server (NTRS)
Arge, C. N.; Mullan, D. J.; Dolginov, A. Z.
1995-01-01
Using published data on magnetic fields, radii, masses, and rotation, we have compiled a data set of magnetic moments mu and angular momenta L for stars and planets. In our subsample of hotter stars (classes A, B, and O), there are 171 objects. In the subsample of cooler stars (classes F, G, K, and M), there are 54 objects. We include 33 white dwarfs, of which 19 are in cataclysmic variables. The pulsar subsample contains 32 pulsars in binaries and 429 isolated pulsars. Som subsamples exhibit significant empirical correlations between log mu and log L. For the hot and cool stars, the correlations are positive. However, the hot-star correlation is significantly shallower than for the cool stars. In the solar system subsample, the correlation has essentially the same slope as for the cool stars, although the magnetic moments are two to three orders of magnitude smaller for the solar system objects at a given L value. For isolated white dwarfs, the correlations are weak or absent. Pulsars and white dwarfs in close binaries show strong negative correlations: the results are quantitatively consistent with magnetically enforced synchronism with the orbital period. When we consider the centers of gravity of the different subsamples of objects, a significant positive correlation appears between log mu and log L.
Determination of the Magnetic Moments of Transition Metal Complexes Using Rare Earth Magnets
NASA Astrophysics Data System (ADS)
de Berg, Kevin C.; Chapman, Kenneth J.
2001-05-01
This paper describes how powerful neodymium magnets and an electronic balance can be used to determine magnetic moments and susceptibilities of transition metal complexes. The technique is an improvement on one previously reported (J. Chem. Educ. 1998, 75, 61) and allows the effect of temperature on paramagnetism to be studied. Results consistent with the Curie law are reported and a theoretical background to the measurement of magnetic moments is given to explain why magnetic field strength and its gradient are important to the technique described.
Manipulation of magnetic moment using the spin current from magnetic and non-magnetic materials
NASA Astrophysics Data System (ADS)
Liu, Luqiao
This thesis summarizes my studies on the effect of spin transfer torque on metallic ferromagnets. The spin current for generating the spin torque is either from ferromagnetic electrode through the spin filtering effect, or from nonmagnetic material through the spin Hall effect (SHE). In the experiment using the spin filtering effect, the current flows vertically through the nanoscale spin valve geometries. I will describe the fabrication process that I used to make the nanopillar structure and the strategy that I developed to reduce the critical current. In the experiment utilizing the SHE, the current flows within the film plane and the spin current is injected transversely from the non-magnetic (NM) film into the adjacent ferromagnetic (FM) layer. I will present five studies that I made to characterize the properties of the SHE and its influence on the magnetic moment. In the first study, I employed the spin torque ferromagnetic resonance (FMR) technique to determine the spin Hall angle. In this experiment, radio frequency current was applied onto the NM/FM bilayer and FMR was induced by the resultant oscillating spin current. By looking into the amplitude of the FMR signal, I was able to get the value of the spin Hall angle. In the second and third studies, I demonstrated that the SHE could be utilized to switch magnetic moment of both perpendicularly and in-plane magnetized FM films. For the perpendicular case, the spins injected into the FM film exert a torque that is perpendicular to the equilibrium position of the moment and it fights against the restoring anisotropy field and induces switching. For the in-plane case, the spins cause switching through the anti-damping mechanism. In the fourth study, I showed that the SHE could induce persistent magnetic oscillations. DC spin current reduces the magnetic damping to zero and the moment undergoes precession around the applied magnetic field. In the final study, I demonstrated that the SHE switching current can
Magnetic Fields for Neutron Electric Dipole Moment Measurement at TRIUMF
NASA Astrophysics Data System (ADS)
Andalib, Taraneh; Canada-Japan UCN Collaboration Collaboration
2016-09-01
The next generation of electric dipole moment (EDM) experiments are a good probe for Charge-Parity (CP) violating sources of physics beyond the Standard Model. The neutron EDM experiment at TRIUMF initially aims to measure the nEDM to 10-27 e .cm by using a new superfluid He ultracold neutron (UCN) source and is expected to yield the highest density of UCN in the world. The experiment employs a room temperature Ramsey Resonance technique. One of the leading systematic uncertainties in the experiment is expected to arise from the magnetic fields fluctuations, where pT level stability over hundreds of seconds and nT/m homogeneity is required. The stability of the magnetic field within a magnetically shielded volume is influenced by a number of factors such as the dependence of the internally generated magnetic field on the magnetic permeability μ of the shield material. Some experiments were conducted to measure the temperature dependence of the magnetic permeability of the shield material which is required to adequately design the next generation nEDM experiment at TRIUMF.
The magnetic moments of the proton and the antiproton
NASA Astrophysics Data System (ADS)
Ulmer, S.; Mooser, A.; Blaum, K.; Braeuninger, S.; Franke, K.; Kracke, H.; Leiteritz, C.; Matsuda, Y.; Nagahama, H.; Ospelkaus, C.; Rodegheri, C. C.; Quint, W.; Schneider, G.; Smorra, C.; Van Gorp, S.; Walz, J.; Yamazaki, Y.
2014-04-01
Recent exciting progress in the preparation and manipulation of the motional quantum states of a single trapped proton enabled the first direct detection of the particle's spin state. Based on this success the proton magnetic moment μp was measured with ppm precision in a Penning trap with a superimposed magnetic field inhomogeneity. An improvement by an additional factor of 1000 in precision is possible by application of the so-called double Penning trap technique. In a recent paper we reported the first demonstration of this method with a single trapped proton, which is a major step towards the first direct high-precision measurement of μp. The techniques required for the proton can be directly applied to measure the antiproton magnetic moment μp. An improvement in precision of μp by more than three orders of magnitude becomes possible, which will provide one of the most sensitive tests of CPT invariance. To achieve this research goal we are currently setting up the Baryon Antibaryon Symmetry Experiment (BASE) at the antiproton decelerator (AD) of CERN.
The Permanent and Inductive Magnetic Moments of Ganymede
NASA Technical Reports Server (NTRS)
Kivelson, M. G.; Khurana, K. K.; Volwerk, M.
2002-01-01
Data acquired by the Galileo magnetometer on five passes by Ganymede have been used to characterize Ganymede's internal magnetic moments. Three of the five passes were useful for determination of the internal moments through quadrupole order. Models representing the internal field as the sum of dipole and quadrupole terms or as the sum of a permanent dipole field upon which is superimposed an induced magnetic dipole driven by the time varying component of the externally imposed magnetic field of Jupiter's magnetosphere give equally satisfactory fits to the data. The permanent dipole moment has an equatorial field magnitude 719 nT and is tilted by 176 degrees from the spin axis with the pole in the southern hemisphere rotated by 24 degrees from the Jupiter-facing meridian plane towards the trailing hemisphere. The data are consistent with an inductive response of a good electrical conductor of radius approximately 1 Ganymede radius. Although the data do not enable us to establish the presence of an inductive response beyond doubt, we favor the inductive response model because it gives a good fit to the data using only 4 parameters to describe the internal sources of fields, whereas the equally good dipole plus quadrupole fit requires 8 parameters. An inductive response is consistent with a buried conducting shell, probably liquid water with dissolved electrolytes, somewhere in the first few hundred km below Ganymede's surface. The depth at which the ocean is buried beneath the surface is somewhat uncertain, but our favored model suggests a depth of order 150 kilometers. As both temperature and pressure increase with depth and the melting temperature of pure ice decreases to a minimum at approximately 170 kilometer depth, it seems possible that near this location, a layer of water would be sandwiched between layers of ice.
Tau anomalous magnetic moment in γγ colliders
NASA Astrophysics Data System (ADS)
Peressutti, Javier; Sampayo, Oscar A.
2012-08-01
We investigate the possibility of setting model independent limits for a nonstandard anomalous magnetic moment aτNP of the tau lepton, in future γγ colliders based on Compton backscattering. For a hypothetical collider we find that, at various levels of confidence, the limits for aτNP could be improved, compared to previous studies based on LEP1, LEP2 and SLD data. We show the results for a realistic range of the center of mass energy of the e+e- collider. As a more direct application, we also present the results of the simulation for the photon collider at the TESLA project.
Table of nuclear magnetic dipole and electric quadrupole moments
Stone, N.J. . E-mail: n.stone1@physics.oxford.ac.uk
2005-05-01
The table is a compilation of experimental measurements of static magnetic dipole and electric quadrupole moments of ground states and excited states of atomic nuclei throughout the periodic table. To aid identification of the states, their excitation energy, half-life, spin, and parity are given, along with a brief indication of the method and any reference standard used in the particular measurement. The literature search covers the period to late 2004. Many of the entries prior to 1988 follow those in Raghavan [At. Data Nucl. Data Tables 42 (1989) 189].
Production of Spin Polarized 58Cu and its Magnetic Moment
NASA Astrophysics Data System (ADS)
Mihara, Mototsugu; Ishibashi, Yoko; Abe, Yasushi; Kamisho, Yasuto; Morita, Yusuke; Ohno, Junichi; Tanaka, Masaomi; Shinozaki, Shinichi; Kanbe, Ryosuke; Fukuda, Mitsunori; Matsuta, Kensaku; Ozawa, Akira; Nagae, Daisuke; Inaba, Seiki; Okada, Shunsuke; Saito, Yuta; Ueno, Hideki; Yamada, Kazunari; Izumikawa, Takuji; Ohtsubo, Takashi; Momota, Sadao; Nishimura, Daiki; Suzuki, Takeshi; Yamaguchi, Takayuki; Kobayashi, Yoshio; Imamura, Kei; Yang, Xiaofei; Nagatomo, Takashi; Minamisono, Tadanori; Takechi, Maya; Ogura, Masako; Matsukawa, Kazuhito; Shirai, Koun; Fujimura, Takumi
Spin polarization of short-lived β emitter 58Cu was generated through the charge exchange reaction of 58Ni on a Be target at 63 MeV/u and the β-NQR spectrum of 58Cu in Si was measured at 15 K. As a result, the 58Cu magnetic dipole moment μ [58Cu] was determined to be | μ [{}58Cu] | = (0.58 ± 0.01)μ N, which is in agreement with the recent result using collinear laser spectroscopy.
Nelson, D.H.; Barale, P.J.; Green, M.I.; Van Dyke, D.A.
1987-09-01
Since May 1985, The Magnetic Measurements Engineering Group at LBL has measured and sorted a total of 3834 permanent magnet blocks. These magnetic blocks have been used in the construction of various successful beam-line elements including dipoles, quadrupoles, and wigglers. We report on observed variations in magnetic moments among blocks supplied by five manufacturers, describe the operational capabilities (accuracy, precision, and resolution) of the LBL Magnetic-moment Measurement and Sorting System (MMSS), cite the results of comparative calibrations by permanent-magnet manufacturers and other National Laboratories, and suggest criteria for automating the MMSS for measuring the large number of permanent-magnet blocks required for the insertion devices for the projected LBL 1-2 GeV Synchrotron Radiation Source. 14 refs., 2 figs., 2 tabs.
Chirality-driven orbital magnetic moments as a new probe for topological magnetic structures
dos Santos Dias, Manuel; Bouaziz, Juba; Bouhassoune, Mohammed; Blügel, Stefan; Lounis, Samir
2016-01-01
When electrons are driven through unconventional magnetic structures, such as skyrmions, they experience emergent electromagnetic fields that originate several Hall effects. Independently, ground-state emergent magnetic fields can also lead to orbital magnetism, even without the spin–orbit interaction. The close parallel between the geometric theories of the Hall effects and of the orbital magnetization raises the question: does a skyrmion display topological orbital magnetism? Here we first address the smallest systems with nonvanishing emergent magnetic field, trimers, characterizing the orbital magnetic properties from first-principles. Armed with this understanding, we study the orbital magnetism of skyrmions and demonstrate that the contribution driven by the emergent magnetic field is topological. This means that the topological contribution to the orbital moment does not change under continuous deformations of the magnetic structure. Furthermore, we use it to propose a new experimental protocol for the identification of topological magnetic structures, by soft X-ray spectroscopy. PMID:27995909
Magnetic moment formation in metal-organic monolayers
NASA Astrophysics Data System (ADS)
Mabrouk, Manel; Hayn, Roland
2015-11-01
We investigate the electronic and magnetic properties of a two-dimensional polymeric manganese phthalocyanine (Mn-Pc) network and its derivative, the metal-ligand network Mn-TCNB formed by the transition-metal atom Mn and the organic ligand TCNB (1,2,4,5-tetracyanobenzene), using first-principles calculations on the basis of density functional theory (DFT) with the Hubbard-like Coulomb term. Our calculations show that Mn-Pc and Mn-TCNB are metallic. It is found that the Mn-Pc network is more stable than the Mn-TCNB one, and both have a total magnetic moment of about 3 μB . In the case of Mn-Pc, also the local Mn moment is close to 3 μB . But in Mn-TCNB, we find a high spin state S =5 /2 at Mn that is partially screened by unpaired electrons at the ligands. That screening is static in the DFT + U results, but we argue in favor of a dynamical screening in reality. Using our proper model calculation on the basis of a suitable model Hamiltonian, we explain the ab initio calculations, analyze the partial screening effect that exists in the two-dimensional Mn-TCNB network, and compare both systems.
Magnetic moments induce strong phonon renormalization in FeSi
Krannich, S.; Sidis, Y.; Lamago, D.; Heid, R.; Mignot, J.-M.; Löhneysen, H. v.; Ivanov, A.; Steffens, P.; Keller, T.; Wang, L.; Goering, E.; Weber, F.
2015-01-01
The interactions of electronic, spin and lattice degrees of freedom in solids result in complex phase diagrams, new emergent phenomena and technical applications. While electron–phonon coupling is well understood, and interactions between spin and electronic excitations are intensely investigated, only little is known about the dynamic interactions between spin and lattice excitations. Noncentrosymmetric FeSi is known to undergo with increasing temperature a crossover from insulating to metallic behaviour with concomitant magnetic fluctuations, and exhibits strongly temperature-dependent phonon energies. Here we show by detailed inelastic neutron-scattering measurements and ab initio calculations that the phonon renormalization in FeSi is linked to its unconventional magnetic properties. Electronic states mediating conventional electron–phonon coupling are only activated in the presence of strong magnetic fluctuations. Furthermore, phonons entailing strongly varying Fe–Fe distances are damped via dynamic coupling to the temperature-induced magnetic moments, highlighting FeSi as a material with direct spin–phonon coupling and multiple interaction paths. PMID:26611619
Magnetic moments induce strong phonon renormalization in FeSi.
Krannich, S; Sidis, Y; Lamago, D; Heid, R; Mignot, J-M; Löhneysen, H v; Ivanov, A; Steffens, P; Keller, T; Wang, L; Goering, E; Weber, F
2015-11-27
The interactions of electronic, spin and lattice degrees of freedom in solids result in complex phase diagrams, new emergent phenomena and technical applications. While electron-phonon coupling is well understood, and interactions between spin and electronic excitations are intensely investigated, only little is known about the dynamic interactions between spin and lattice excitations. Noncentrosymmetric FeSi is known to undergo with increasing temperature a crossover from insulating to metallic behaviour with concomitant magnetic fluctuations, and exhibits strongly temperature-dependent phonon energies. Here we show by detailed inelastic neutron-scattering measurements and ab initio calculations that the phonon renormalization in FeSi is linked to its unconventional magnetic properties. Electronic states mediating conventional electron-phonon coupling are only activated in the presence of strong magnetic fluctuations. Furthermore, phonons entailing strongly varying Fe-Fe distances are damped via dynamic coupling to the temperature-induced magnetic moments, highlighting FeSi as a material with direct spin-phonon coupling and multiple interaction paths.
Directional Antineutrino Detection
NASA Astrophysics Data System (ADS)
Safdi, B. R.; Suerfu, J.
2014-12-01
We propose the first truly directional antineutrino detector for antineutrinos near the threshold for the inverse beta decay (IBD) of hydrogen, with potential applications including the spatial mapping of geo-neutrinos, searches for stellar antineutrinos, and the monitoring of nuclear reactors. The detector consists of adjacent and separated target and neutron-capture layers. The IBD events, which result in a neutron and a positron, take place in the target layers. These layers are thin enough so that the neutrons escape without scattering elastically. The neutrons are detected in the thicker neutron-capture layers. The location of the IBD event is determined from the energy deposited by the positron as it slows in the medium and from the two gamma rays that come from the positron annihilation. Since the neutron recoils in the direction of the antineutrino's motion, a line may then be drawn between the IBD event location and the neutron-capture location to approximate the antineutrino's velocity. In some events, we may even measure the positron's velocity, which further increases our ability to reconstruct the antineutrino's direction of motion. Our method significantly improves upon previous methods by allowing the neutron to freely travel a long distance before diffusing and being captured. Moreover, our design is a straightforward modification of existing antineutrino detectors; a prototype could easily be built with existing technology. We verify our design through Monte Carlo simulations in Geant4, using commercially-available boron-loaded plastic scintillators for the target and neutron-capture layer materials. We are able to discriminate from background using multiple coincidence signatures within a short, ~microsecond time interval. We conclude that the detector could likely operate above ground with minimal shielding.
Current Noise from a Magnetic Moment in a Helical Edge
NASA Astrophysics Data System (ADS)
Väyrynen, Jukka I.; Glazman, Leonid I.
2017-03-01
We calculate the two-terminal current noise generated by a magnetic moment coupled to a helical edge of a two-dimensional topological insulator. When the system is symmetric with respect to in-plane spin rotation, the noise is dominated by the Nyquist component even in the presence of a voltage bias V . The corresponding noise spectrum S (V ,ω ) is determined by a modified fluctuation-dissipation theorem with the differential conductance G (V ,ω ) in place of the linear one. The differential noise ∂S /∂V , commonly measured in experiments, is strongly dependent on frequency on a small scale τK-1≪T set by the Korringa relaxation rate of the local moment. This is in stark contrast to the case of conventional mesoscopic conductors where ∂S /∂V is frequency independent and defined by the shot noise. In a helical edge, a violation of the spin-rotation symmetry leads to the shot noise, which becomes important only at a high bias. Uncharacteristically for a fermion system, this noise in the backscattered current is super-Poissonian.
Dynamically fluctuating electric dipole moments in fullerene-based magnets.
Kambe, Takashi; Oshima, Kokichi
2014-09-19
We report here the direct evidence of the existence of a permanent electric dipole moment in both crystal phases of a fullerene-based magnet--the ferromagnetic α-phase and the antiferromagnetic α'-phase of tetra-kis-(dimethylamino)-ethylene-C60 (TDAE-C60)--as determined by dielectric measurements. We propose that the permanent electric dipole originates from the pairing of a TDAE molecule with surrounding C60 molecules. The two polymorphs exhibit clear differences in their dielectric responses at room temperature and during the freezing process with dynamically fluctuating electric dipole moments, although no difference in their room-temperature structures has been previously observed. This result implies that two polymorphs have different local environment around the molecules. In particular, the ferromagnetism of the α-phase is founded on the homogeneous molecule displacement and orientational ordering. The formation of the different phases with respect to the different rotational states in the Jahn-Teller distorted C60s is also discussed.
Probing neutrino magnetic moments at the Spallation Neutron Source facility
NASA Astrophysics Data System (ADS)
Kosmas, T. S.; Miranda, O. G.; Papoulias, D. K.; Tórtola, M.; Valle, J. W. F.
2015-07-01
Majorana neutrino electromagnetic properties are studied through neutral current coherent neutrino-nucleus scattering. We focus on the potential of the recently planned COHERENT experiment at the Spallation Neutron Source to probe muon-neutrino magnetic moments. The resulting sensitivities are determined on the basis of a χ2 analysis employing realistic nuclear structure calculations in the context of the quasiparticle random phase approximation. We find that they can improve existing limits by half an order of magnitude. In addition, we show that these facilities allow for standard model precision tests in the low energy regime, with a competitive determination of the weak mixing angle. Finally, they also offer the capability to probe other electromagnetic neutrino properties, such as the neutrino charge radius. We illustrate our results for various choices of experimental setup and target material.
Lattice Calculations and the Muon Anomalous Magnetic Moment
NASA Astrophysics Data System (ADS)
Marinković, Marina Krstić
2017-07-01
Anomalous magnetic moment of the muon, a_{μ }=(g_{μ }-2)/2, is one of the most precisely measured quantities in particle physics and it provides a stringent test of the Standard Model. The planned improvements of the experimental precision at Fermilab and at J-PARC propel further reduction of the theoretical uncertainty of a_{μ }. The hope is that the efforts on both sides will help resolve the current discrepancy between the experimental measurement of a_{μ } and its theoretical prediction, and potentially gain insight into new physics. The dominant sources of the uncertainty in the theoretical prediction of a_{μ } are the errors of the hadronic contributions. I will discuss recent progress on determination of hadronic contributions to a_{μ } from lattice calculations.
On the measurement of the neutrino magnetic moment
NASA Astrophysics Data System (ADS)
Beda, A. G.; Demidova, E. V.; Starostin, A. S.; Gavrilov, M. G.; Brudanin, V. B.; Egorov, V. G.
2002-07-01
The present status of searches for the neutrino magnetic moment (NMM) down to 3×10 -11 μ B is briefly discussed. The low background Ge-NaI spectrometer GEMMA constructed in ITEP for NMM measurement is described and the results of the test background measurements at a small depth of 5 m.w.e in ITEP are reported. The analysis of these results shows that the limit on NMM at the level (2 ÷ 3)·10 -11 μ B can be achieved during 2 year duration of measurements with spectrometer GEMMA at Kalininskaya Nuclear Power Plant (KNPP). The prospects of breakthrough to the limit on NMM about 10 -12 μ B are outlined.
Daugas, J. M.; Gaudefroy, L.; Meot, V.; Morel, P.; Rosse, B.; Hass, M.; Kumar, V.; Angelique, J. C.; Simpson, G. S.; Balabanski, D. L.; Fiori, E.; Georgiev, G.; Lozeva, R.; Force, C.; Grevy, S.; Stodel, Ch.; Thomas, J. C.; Kameda, D.; Matea, I.; Singh, B. S. Nara
2008-11-11
The gyromagnetic factor of the isomeric state of {sup 43}S has been measured using the Time Dependent Perturbed Angular Distribution (TDPAD) technique. The isomer was produced and spin aligned via the fragmentation of a 60 AMeV {sup 48}Ca beam at the GANIL facility. The deduced magnetic moment confirms the 7/2{sup -} spin/parity of the isomeric state and shows, for the first time, the intruder nature of the ground state. Comparison of the experimental values with Shell Model and mean-field based calculations were performed revealing a pronounced ground state deformation and a quasi-spherical isomeric state. A new isomeric state has been observed in the {sup 42}P.
The Polarization and Magnetic Moment of the $\\Sigma^- Hyperon$
Deck, Leslie Ludwig
1982-11-01
The magnitude of the polarization of 516,229 inclusively produced $\\Sigma^-$'s has been measured to be 15.5±3.6%. The $\\Sigma^-$'s were produced by 400 GeV/c protons on Be at angles of $\\pm$7.5 mr with respect to the incident proton direction and had momenta between 120 and 290 GeV/c, with a mean momentum of 176 GeV/c. The polarization was measured from the asymmetry in the decay $\\Sigma^- \\eta + \\pi^-$ The $\\Sigma^-$ magnetic moment was also determined to be -0.89 $\\pm$ 0.l4 $\\mu_N$ corresponding to an anomalous precession angle of 11$^{\\circ}$+15°.
Simple optical measurement of the magnetic moment of magnetically labeled objects
NASA Astrophysics Data System (ADS)
Heidsieck, Alexandra; Rudigkeit, Sarah; Rümenapp, Christine; Gleich, Bernhard
2017-04-01
The magnetic moment of magnetically labeled cells, microbubbles or microspheres is an important optimization parameter for many targeting, delivery or separation applications. The quantification of this property is often difficult, since it depends not only on the type of incorporated nanoparticle, but also on the intake capabilities, surface properties and internal distribution. We describe a method to determine the magnetic moment of those carriers using a microscopic set-up and an image processing algorithm. In contrast to other works, we measure the diversion of superparamagnetic nanoparticles in a static fluid. The set-up is optimized to achieve a homogeneous movement of the magnetic carriers inside the magnetic field. The evaluation is automated with a customized algorithm, utilizing a set of basic algorithms, including blob recognition, feature-based shape recognition and a graph algorithm. We present example measurements for the characteristic properties of different types of carriers in combination with different types of nanoparticles. Those properties include velocity in the magnetic field as well as the magnetic moment. The investigated carriers are adherent and suspension cells, while the used nanoparticles have different sizes and coatings to obtain varying behavior of the carriers.
Rabi, the proton magnetic moment, and the ‘2-wire' magnet, 1931-34
NASA Astrophysics Data System (ADS)
Forman, Paul
2001-04-01
With the assistance of Gregory Breit, I.I. Rabi, at Columbia University, worked out in 1931 a method to determine the spin (not the magnetic moment) of atomic nuclei by deflecting an atomic beam of the isotope in question in a weak, but long, inhomogeneous magnetic field. Crucial to this method was that it required no exact knowledge of that field. When the sensational result -- µp = 2.5µ_Bohr(m_e/m_p) -- from Otto Stern's deflection of a beam of hydrogen molecules in a strong magnetic field became known late in 1932, its confirmation by another laboratory, preferably by another method, seemed urgent. No one else had the refined technique to reproduce Stern's experiment. But because the hydrogen electronic wave function was known, the Breit-Rabi technique was susceptible of extension in this case to the measurement of the magnetic moment of the proton - - but only with accurate knowledge of the magnetic field and field gradient traversed by the atomic hydrogen beam. To this end Rabi introduced the '2-wire' magnet, producing a weak field and uniform gradient that could be calculated rather than measured. This field configuration quickly came to be used in all magnetic deflection experiments in Rabi's laboratory, first as produced directly by electric currents, and subsequently as emulated in iron electromagnets in order to achieve the higher magnetic fields required by molecular beam magnetic resonance experiments from 1937 onward.
Rabi, the proton magnetic moment, and the ¡2-wire¢ magnet, 1931-34
NASA Astrophysics Data System (ADS)
Forman, Paul
2001-04-01
With the assistance of Gregory Breit, I.I. Rabi, at Columbia University, worked out in 1931 a method to determine the spin (not the magnetic moment) of atomic nuclei by deflecting an atomic beam of the isotope in question in a weak, but long, inhomogeneous magnetic field. Crucial to this method was that it required no exact knowledge of that field. When the sensational result: p = 2.5:_Bohr(m_e/m_p) from Otto Stern's deflection of a beam of hydrogen molecules in a strong magnetic field became known late in 1932, its confirmation by another laboratory, preferably by another method, seemed urgent. No one else had the refined technique to reproduce Stern's experiment. But because the hydrogen electronic wave function was known, the Breit Rabi technique was susceptible of extension in this case to the measurement of the magnetic moment of the proton but only with accurate knowledge of the magnetic field and field gradient traversed by the atomic hydrogen beam. To this end Rabi introduced the '2 wire' magnet, producing a weak field and uniform gradient that could be calculated rather than measured. This field configuration quickly came to be used in all magnetic deflection experiments in Rabi's laboratory, first as produced directly by electric currents, and subsequently as emulated in iron electromagnets in order to achieve the higher magnetic fields required by molecular beam magnetic resonance experiments from 1937 onward.
Touchless attitude correction for satellite with constant magnetic moment
NASA Astrophysics Data System (ADS)
Ao, Hou-jun; Yang, Le-ping; Zhu, Yan-wei; Zhang, Yuan-wen; Huang, Huan
2017-09-01
Rescue of satellite with attitude fault is of great value. Satellite with improper injection attitude may lose contact with ground as the antenna points to the wrong direction, or encounter energy problems as solar arrays are not facing the sun. Improper uploaded command may set the attitude out of control, exemplified by Japanese Hitomi spacecraft. In engineering practice, traditional physical contact approaches have been applied, yet with a potential risk of collision and a lack of versatility since the mechanical systems are mission-specific. This paper puts forward a touchless attitude correction approach, in which three satellites are considered, one having constant dipole and two having magnetic coils to control attitude of the first. Particular correction configurations are designed and analyzed to maintain the target's orbit during the attitude correction process. A reference coordinate system is introduced to simplify the control process and avoid the singular value problem of Euler angles. Based on the spherical triangle basic relations, the accurate varying geomagnetic field is considered in the attitude dynamic mode. Sliding mode control method is utilized to design the correction law. Finally, numerical simulation is conducted to verify the theoretical derivation. It can be safely concluded that the no-contact attitude correction approach for the satellite with uniaxial constant magnetic moment is feasible and potentially applicable to on-orbit operations.
Observation of the Nuclear Magnetic Octupole Moment of 137Ba+
NASA Astrophysics Data System (ADS)
Hoffman, Matthew
Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.
Kondo screening of the spin and orbital magnetic moments of Fe impurities in Cu
NASA Astrophysics Data System (ADS)
Joly, L.; Kappler, J.-P.; Ohresser, P.; Sainctavit, Ph.; Henry, Y.; Gautier, F.; Schmerber, G.; Kim, D. J.; Goyhenex, C.; Bulou, H.; Bengone, O.; Kavich, J.; Gambardella, P.; Scheurer, F.
2017-01-01
We use x-ray magnetic circular dichroism to evidence the effect of correlations on the local impurity magnetic moment in an archetypal Kondo system, namely, a dilute Cu:Fe alloy. Applying the sum rules on the Fe L2 ,3 absorption edges, the evolution of the spin and orbital moments across the Kondo temperature are determined separately. The spin moment presents a crossover from a nearly temperature-independent regime below the Kondo temperature to a paramagneticlike regime above. Conversely, the weak orbital moment shows a temperature-independent behavior in the whole temperature range, suggesting different Kondo screening temperature scales for the spin and orbital moments.
Object representation and magnetic moments in thin alkali films
NASA Astrophysics Data System (ADS)
Garrett, Douglas C.
2008-10-01
impurities 1/taus and their magnetic cross section sigmas are calculated. We find that single V surface impurities are magnetic while single Mo and Co impurities are non-magnetic. Co surface clusters are magnetic. In chapter 7, thin films of Na, K, Rb and Cs are quench condensed, then covered with 1/100 of a mono-layer of Ti and finally covered with the original host. The magnetization of the films is measured by means of the anomalous Hall effect. An anomalous Hall resistance RAHE is observed for Ti on the surface of K, Rb and Cs and for Ti inside of Cs. Essentially the RAHE varies linearly with the magnetic field and is inversely proportional to the inverse temperature. A small non-linearity of RAHE suggests a Ti moment of about 1microB.
-Interface effects on the magnetic moment of Co and Cu in CoCu granular alloys
Garcia Prieto, A.; Fdez-Gubieda, M.L.; Chaboy, J.; Laguna-Marco, M.A.; Muro, T.; Nakamura, T.
2005-12-01
We report on x-ray magnetic circular dichroism experiments performed on Co{sub 5}Cu{sub 95} annealed granular alloys with giant magnetoresistance. Results on the Co-L{sub 2,3} edge evidence a direct correlation between the Co orbital and spin magnetic moment and the Co clusters interfacial roughness. On the other hand, we have found dichroism on the Cu-L{sub 2,3} edge, revealing an induced magnetic polarization of the Cu interfacial atoms. The magnetic moment of the Cu atoms is mainly of spin character and is ferromagnetically coupled with the Co magnetic moment.
NASA Astrophysics Data System (ADS)
Bubnov, A. F.; Gubina, N. V.; Zhukovsky, V. Ch.
2017-07-01
In this paper, we consider vacuum polarization effects in the model of charged fermions with anomalous magnetic moment and axial-vector interaction term in a constant and uniform magnetic field. Nontrivial corrections to the effective Lagrangian from the anomalous moment and axial-vector term are calculated with account for various configurations of parameters of the model. An analogue of the chiral magnetic effect in the axial-vector background as well as a vacuum current induced under the combined action of the anomalous magnetic moment of fermions and the axial vector background in a magnetic field is also calculated.
Stepanow, Sebastian; Honolka, Jan; Gambardella, Pietro; Vitali, Lucia; Abdurakhmanova, Nasiba; Tseng, Tzu-Chun; Rauschenbach, Stephan; Tait, Steven L; Sessi, Violetta; Klyatskaya, Svetlana; Ruben, Mario; Kern, Klaus
2010-09-01
The magnetic properties of isolated TbPc(2) molecules supported on a Cu(100) surface are investigated by X-ray magnetic circular dichroism at 8 K in magnetic fields up to 5 T. The crystal field and magnetic properties of single molecules are found to be robust upon adsorption on a metal substrate. The Tb magnetic moment has Ising-like magnetization; XMCD spectra combined with multiplet calculations show that the saturation orbital and spin magnetic moment values reach 3 and 6 mu(B), respectively.
Muon anomalous magnetic moment through the leptonic Higgs portal
NASA Astrophysics Data System (ADS)
Batell, Brian; Lange, Nicholas; McKeen, David; Pospelov, Maxim; Ritz, Adam
2017-04-01
An extended Higgs sector may allow for new scalar particles well below the weak scale. In this work, we present a detailed study of a light scalar S with enhanced coupling to leptons, which could be responsible for the existing discrepancy between experimental and theoretical determinations of the muon anomalous magnetic moment. We present an ultraviolet completion of this model in terms of the lepton-specific two-Higgs-doublet model and an additional scalar singlet. We then analyze a plethora of experimental constraints on the universal low energy model, and this UV completion, along with the sensitivity reach at future experiments. The most relevant constraints originate from muon and kaon decays, electron beam dump experiments, electroweak precision observables, rare Bd and Bs decays and Higgs branching fractions. The properties of the leptonic Higgs portal imply an enhanced coupling to heavy leptons, and we identify the most promising search mode for the high-luminosity electron-positron colliders as e++e-→τ++τ-+S →τ++τ-+ℓ+ℓ¯, where ℓ=e , μ . Future analyses of existing data from BABAR and Belle, and from the upcoming Belle II experiment, will enable tests of this model as a putative solution to the muon g -2 problem for mS<3.5 GeV .
NASA Astrophysics Data System (ADS)
Slutsky, S.; Swank, C. M.; Biswas, A.; Carr, R.; Escribano, J.; Filippone, B. W.; Griffith, W. C.; Mendenhall, M.; Nouri, N.; Osthelder, C.; Pérez Galván, A.; Picker, R.; Plaster, B.
2017-08-01
A magnetic coil operated at cryogenic temperatures is used to produce spatial, relative field gradients below 6 ppm/cm, stable for several hours. The apparatus is a prototype of the magnetic components for a neutron electric dipole moment (nEDM) search, which will take place at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory using ultra-cold neutrons (UCN). That search requires a uniform magnetic field to mitigate systematic effects and obtain long polarization lifetimes for neutron spin precession measurements. This paper details upgrades to a previously described apparatus [1], particularly the introduction of super-conducting magnetic shielding and the associated cryogenic apparatus. The magnetic gradients observed are sufficiently low for the nEDM search at SNS.
NASA Astrophysics Data System (ADS)
Balaev, D. A.; Dubrovskii, A. A.; Krasikov, A. A.; Stolyar, S. V.; Iskhakov, R. S.; Ladygina, V. P.; Khilazheva, E. D.
2013-10-01
The magnetic properties of antiferromagnetic nanoparticles of FeOOH · nH2O with sizes of 3-7 nm, which are products of vital functions of Klebsiella oxytoca bacteria, have been studied. Particles exhibit a superparamagnetic behavior. The characteristic blocking temperature is 23 K. Analysis of the magnetization curves shows that the mechanism of the formation of the uncompensated magnetic moment of particles is the random decompensation of magnetic moments of Fe3+ ions both on the surface and in the bulk of the antiferromagnetic particle. In this mechanism, the exchange coupling between the uncompensated magnetic moment of the particle and its antiferromagnetic "core" is implemented. It has been found that the temperature dependence of the uncompensated magnetic moment has the form 1 — const T 2.
NASA Astrophysics Data System (ADS)
Kan, Daisuke; Mizumaki, Masaichiro; Nishimura, Tomoe; Shimakawa, Yuichi
2016-12-01
Using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) spectroscopy, we evaluated the orbital magnetic moments of itinerant ferromagnet SrRu O3 (SRO) epitaxial thin films with interfacially controlled magnetic anisotropy. We found that the orbital moment is closely correlated with the SRO's magnetic anisotropy, which can be controlled by interfacially engineering the Ru O6 octahedral rotations. For the monoclinic film with magnetization along the direction 45° from the out-of-plane direction, the orbital moment is ≈-0.1 μB/Ru along the magnetic easy axis direction and is aligned antiparallel to the direction of the spin magnetic moments. For the tetragonal film with in-plane magnetization, on the other hand, the out-of-plane component of the orbital moment is as small as ≈-0.04 μB/Ru , accounting for the film's in-plane magnetic anisotropy. Our results highlight that the magnetic anisotropy of SRO can be controlled by engineering the orbital magnetic moment through the octahedral distortions.
Gruyters, M; Schmitz, D
2008-02-22
Exchange bias in layered CoO/Fe structures is investigated by x-ray resonant magnetic reflectivity (XRMR) measurements. Element-specific hysteresis loops are obtained from x-ray magnetic circular dichroism effects in the XRMR spectra. Evidence is provided for the existence of different types of uncompensated moments in the antiferromagnetic material. Explanations are given for the microscopic nature of these moments and the complex exchange interactions that determine the magnetization reversal in exchange bias systems.
Gyrotropic Magnetic Effect and the Magnetic Moment on the Fermi Surface
NASA Astrophysics Data System (ADS)
Zhong, Shudan; Moore, Joel E.; Souza, Ivo
2016-02-01
The current density jB induced in a clean metal by a slowly-varying magnetic field B is formulated as the low-frequency limit of natural optical activity, or natural gyrotropy. Working with a multiband Pauli Hamiltonian, we obtain from the Kubo formula a simple expression for αij GME=jiB/Bj in terms of the intrinsic magnetic moment (orbital plus spin) of the Bloch electrons on the Fermi surface. An alternate semiclassical derivation provides an intuitive picture of the effect, and takes into account the influence of scattering processes in dirty metals. This "gyrotropic magnetic effect" is fundamentally different from the chiral magnetic effect driven by the chiral anomaly and governed by the Berry curvature on the Fermi surface, and the two effects are compared for a minimal model of a Weyl semimetal. Like the Berry curvature, the intrinsic magnetic moment should be regarded as a basic ingredient in the Fermi-liquid description of transport in broken-symmetry metals.
Meson-exchange-current corrections to magnetic moments in quantum hadrodynamics
Morse, T.M.
1990-01-01
Corrections to the magnetic moments of the non-relativistic shell model (Schmidt lines) have a long history. In the early fifties calculations of pion exchange and core polarization contributions to nuclear magnetic moments were initiated. These calculations matured by the early eighties to include other mesons and the delta isobar. Relativistic nuclear shell model calculations are relatively recent. Meson exchange and the delta isobar current contributions to the magnetic moments of the relativistic shell model have remained largely unexplored. The disagreement between the valence values of spherical relativistic mean-field models and experiment was a major problem with early (1975-1985) quantum hydrodynamics (QHD) calculations of magnetic moments. Core polarization calculations (1986-1988) have been found to resolve the large discrepancy, predicting isoscalar magnetic moments to within typically five percent of experiment. The isovector magnetic moments, however, are about twice as far from experiment with an average discrepancy of about ten percent. The pion, being the lightest of the mesons, has historically been expected to dominate isovector corrections. Because this has been found to be true in non-relativistic calculations, the author calculated the pion corrections in the framework of QHD. The seagull and in-flight pion exchange current diagram corrections to the magnetic moments of eight finite nuclei (plus or minus one valence nucleon from the magic A = 16 and A = 40 doubly closed shell systems) are calculated in the framework of QHD, and compared with earlier non-relativistic calculations and experiment.
Neutron stars including the effects of chaotic magnetic fields and anomalous magnetic moments
NASA Astrophysics Data System (ADS)
Wu, Fei; Wu, Chen; Ren, Zhong-Zhou
2017-04-01
The relativistic mean field (RMF) FSUGold model extended to include hyperons is employed to study the properties of neutron stars with strong magnetic fields. The chaotic magnetic field approximation is utilized. The effect of anomalous magnetic moments (AMMs) is also investigated. It is shown that the equation of state (EOS) of neutron star matter is stiffened by the presence of the magnetic field, which increases the maximum mass of a neutron star by around 6%. The AMMs only have a small influence on the EOS of neutron star matter, and increase the maximum mass of a neutron star by 0.02M sun. Neutral particles are spin polarized due to the presence of the AMMs. Supported by National Natural Science Foundation of China (11535004, 11375086, 11120101005, 11175085, 11235001), 973 National Major State Basic Research and Development of China (2013CB834400), and Science and Technology Development Fund of Macau (068/2011/A)
NASA Astrophysics Data System (ADS)
Lebedev, A. V.
2015-01-01
Magnetic susceptibility measurements were carried out for magnetite-based fluids over a wide temperature range. The fluids were stabilized with commonly used surfactants (fatty acids) and new surfactants (polypropylene glycol and tallow acids). The coefficients of temperature dependence of the particle magnetic moments were determined by fitting of the measured and calculated values of magnetic susceptibility. The influence of the inter-particle dipole-dipole interaction on the susceptibility was taken into account in the framework of A.O. Ivanov's model. The corrections for thermal expansion were determined by density measurements of the carrier fluid. The obtained values of temperature coefficients correlate to the solidification temperature of the fluid samples. For fluids with a low solidification temperature the value of the temperature coefficient of particle magnetization coincides with its value for bulk magnetite.
Probing the magnetic moment of FePt micromagnets prepared by focused ion beam milling
Overweg, H. C.; Haan, A. M. J. den; Eerkens, H. J.; Bossoni, L.; Oosterkamp, T. H.; Alkemade, P. F. A.; La Rooij, A. L.; Spreeuw, R. J. C.
2015-08-17
We investigate the degradation of the magnetic moment of a 300 nm thick FePt film induced by Focused Ion Beam (FIB) milling. A 1 μm × 8 μm rod is milled out of a film by a FIB process and is attached to a cantilever by electron beam induced deposition. Its magnetic moment is determined by frequency-shift cantilever magnetometry. We find that the magnetic moment of the rod is μ = 1.1 ± 0.1 × 10{sup −12} Am{sup 2}, which implies that 70% of the magnetic moment is preserved during the FIB milling process. This result has important implications for atom trapping and magnetic resonance force microscopy, which are addressed in this paper.
NASA Astrophysics Data System (ADS)
Mein, P.; Uitenbroek, H.; Mein, N.; Bommier, V.; Faurobert, M.
2016-06-01
Context. In the case of unresolved solar structures or stray light contamination, inversion techniques using four Stokes parameters of Zeeman profiles cannot disentangle the combined contributions of magnetic and nonmagnetic areas to the observed Stokes I. Aims: In the framework of a two-component model atmosphere with filling factor f, we propose an inversion method restricting input data to Q , U, and V profiles, thus overcoming ambiguities from stray light and spatial mixing. Methods: The V-moments inversion (VMI) method uses shifts SV derived from moments of V-profiles and integrals of Q2, U2, and V2 to determine the strength B and inclination ψ of a magnetic field vector through least-squares polynomial fits and with very few iterations. Moment calculations are optimized to reduce data noise effects. To specify the model atmosphere of the magnetic component, an additional parameter δ, deduced from the shape of V-profiles, is used to interpolate between expansions corresponding to two basic models. Results: We perform inversions of HINODE SOT/SP data for inclination ranges 0 <ψ< 60° and 120 <ψ< 180° for the 630.2 nm Fe i line. A damping coefficient is fitted to take instrumental line broadening into account. We estimate errors from data noise. Magnetic field strengths and inclinations deduced from VMI inversion are compared with results from the inversion codes UNNOFIT and MERLIN. Conclusions: The VMI inversion method is insensitive to the dependence of Stokes I profiles on the thermodynamic structure in nonmagnetic areas. In the range of Bf products larger than 200 G, mean field strengths exceed 1000 G and there is not a very significant departure from the UNNOFIT results because of differences between magnetic and nonmagnetic model atmospheres. Further improvements might include additional parameters deduced from the shape of Stokes V profiles and from large sets of 3D-MHD simulations, especially for unresolved magnetic flux tubes.
NASA Astrophysics Data System (ADS)
Kurz, Felix; Kampf, Thomas; Buschle, Lukas; Schlemmer, Heinz-Peter; Bendszus, Martin; Heiland, Sabine; Ziener, Christian
2016-12-01
In biological tissue, an accumulation of similarly shaped objects with a susceptibility difference to the surrounding tissue generates a local distortion of the external magnetic field in magnetic resonance imaging. It induces stochastic field fluctuations that characteristically influence proton spin diffusion in the vicinity of these magnetic perturbers. The magnetic field correlation that is associated with such local magnetic field inhomogeneities can be expressed in the form of a dynamic frequency autocorrelation function that is related to the time evolution of the measured magnetization. Here, an eigenfunction expansion for two simple magnetic perturber shapes, that of spheres and cylinders, is considered for restricted spin diffusion in a simple model geometry. Then, the concept of generalized moment analysis, an approximation technique that is applied in the study of (non-)reactive processes that involve Brownian motion, allows to provide analytical expressions for the correlation function for different exponential decay forms. Results for the biexponential decay for both spherical and cylindrical magnetized objects are derived and compared with the frequently used (less accurate) monoexponential decay forms. They are in asymptotic agreement with the numerically exact value of the correlation function for long and short times.
William Detmold; Tiburzi, Brian C.; Walker-Loud, Andre
2010-03-01
Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. We devise combinations of baryon two-point functions in external electric fields to isolate both observables. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how magnetic moments and electric polarizabilities can be determined from lattice QCD simulations in background electric fields. We obtain results for both the neutron and proton. Our study is currently limited to electrically neutral sea quarks.
Magnetic Structure of the Local-moment Antiferromagnet CeCuSn
Chang, S.; Janssen, Y.; Garlea, Vasile O; Zarestky, Jerel L; Nakotte, H.; McQueeney, R. J.
2005-01-01
We report on single-crystal neutron diffraction studies of the local-moment antiferromagnet CeCuSn. The ground-state magnetic structure is characterized by a magnetic wave vector k = (0.115,0,0). The onset of antiferromagnetic order occurs around 12 K with an inflection in the temperature dependence of the magnetic intensities at about 8 K. This is in contrast to bulk measurements, which only show broad features at 8--10 K. The ordered moments are likely reduced from the free-ion moment for Ce.
Planar Hall ring sensor for ultra-low magnetic moment sensing
NASA Astrophysics Data System (ADS)
Hung, Tran Quang; Terki, Ferial; Kamara, Souleymanne; Kim, Kunwoo; Charar, Salam; Kim, CheolGi
2015-04-01
The field sensitivity of a planar Hall effect (PHE) micro-ring type biosensor has been investigated as a function of magnetizing angle of the sensor material, for the sensing of low magnetic moment superparamagnetic labels. The field sensitivity is maximal at a magnetizing angle of α = 20°. At this optimized magnetizing angle, the field sensitivity of a PHE sensor is about 3.6 times higher than that measured at the conventional configuration, α = 90°. This optimization enables the PHE-ring sensor to detect superparamagnetic biolabels with ultra-low magnetic moments down to 4 × 10-13 emu.
Re-creating Gauss's method for non-electrical absolute measurements of magnetic fields and moments
NASA Astrophysics Data System (ADS)
Van Baak, D. A.
2013-10-01
In 1832, Gauss made the first absolute measurements of magnetic fields and of magnetic moments in experiments that are straightforward and instructive to replicate. We show, using rare-earth permanent magnets and a variation of Gauss's technique, that the horizontal component of the ambient geomagnetic field, as well as the size of the magnetic moments of such magnets, can be found. The method shows the connection between the SI and cgs emu unit systems for these quantities and permits an absolute realization of the Ampere with considerable precision.
The local magnetic moment and electron transfer of ZnO-based dilute magnetic semiconductors
NASA Astrophysics Data System (ADS)
Zhuang, Bin; Yang, Yanmin; Zhong, Kehua; Zhang, Jian-Min; Xu, Guigui; Huang, Zhigao
2017-05-01
The electronic structures and magnetic properties of ZnO semiconductors doped with Cu, Co, C, Al and S are studied by first-principles calculation. The electronic transfer among Zn, O and doped atoms, and the differences of the number of electron between spin-up and spin-down, Δs, Δp, Δd for s, p and d orbits of these atoms, are analyzed in detail. It is found that, the ferromagnetic ground state is stabilized by its half-metallic electronic structure, and the strong local magnetic moments in Zn1-xCoxO, Zn1-xCuxO and ZnO1-xCx (x = 5.55%) DMSs originate mainly from the strong hybridizations between Cu-3d and O-2p, Co-3d and O-2p, Zn-3d and C-2p electrons. It is considered that the requirements to give rise to the ferromagnetism in the DMSs are the strong local magnetic moment and the electron transfer. The magnetic coupling in Zn1-xCoxO, Zn1-xCuxO and ZnO1-xCx is also considered to be a RKKY interaction.
Probing the magnetic relaxation and magnetic moment arrangement in a series of Dy4 squares.
Wu, Jianfeng; Lin, Shuang-Yan; Shen, Si; Li, Xiao-Lei; Zhao, Lang; Zhang, Li; Tang, Jinkui
2017-01-31
Three μ4-O bridged Dy4 squares, {[Dy4(μ4-O)(HL(1))4(H2O)4]2(NO3)3(OH)}·2H2O·2CH3OH (1), [Dy4(μ4-O)(HL(2))4(SCN)2]·2H2O·4CH3OH (2) and [Dy4(μ4-O)(H2L(3))2(SCN)2]·6H2O (3) were assembled by using a Schiff base ligand and its dimerized and reduced congener, respectively. These complexes share a similar μ4-O bridged Dy4 core, while, both the coordination geometry and metal-ligand interactions are slightly changed upon the modulation of the ligands, resulting in distinct single-molecular magnetic (SMM) and single-molecular toroic (SMT) properties. In complex 1, the Schiff base ligands are in an antiparallel fashion and all Dy(III) ions are in a similar coordination geometry, realizing the toroidal arrangement of magnetic moments. For complex 2, the reduced ligand H3L(2) in a parallel fashion results in double relaxation processes and a 9-fold increase of the Ueff. Interestingly, with the use of the dimerized ligand H6L(3), we obtained complex 3, which is similar to complex 2, while due to the slight changes of the coordination environment both the single molecular magnetic property and toroidal magnetic moments almost disappeared.
X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu.
Kukreja, R; Bonetti, S; Chen, Z; Backes, D; Acremann, Y; Katine, J A; Kent, A D; Dürr, H A; Ohldag, H; Stöhr, J
2015-08-28
We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{-5}μ_{B} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{-3}μ_{B} per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.
X-ray detection of transient magnetic moments induced by a spin current in Cu
Kukreja, R.; Bonetti, S.; Chen, Z.; Backes, D.; Acremann, Y.; Katine, J.; Kent, A. D.; Durr, H. A.; Ohldag, H.; Stohr, J.
2015-08-24
We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{–5}_{μB} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott’s two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{–3}_{μB} per atom. As a result, this reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.
NASA Astrophysics Data System (ADS)
Ishigami, K.; Yoshimatsu, K.; Toyota, D.; Takizawa, M.; Yoshida, T.; Shibata, G.; Harano, T.; Takahashi, Y.; Kadono, T.; Verma, V. K.; Singh, V. R.; Takeda, Y.; Okane, T.; Saitoh, Y.; Yamagami, H.; Koide, T.; Oshima, M.; Kumigashira, H.; Fujimori, A.
2015-08-01
Thin films of the ferromagnetic metal SrRuO3 (SRO) show a varying easy magnetization axis depending on the epitaxial strain, and undergo a metal-to-insulator transition with decreasing film thickness. We have investigated the magnetic properties of SRO thin films with varying thicknesses fabricated on SrTiO3(001) substrates by soft x-ray magnetic circular dichroism at the Ru M2 ,3 edge. Results have shown that, with decreasing film thickness, the film changes from ferromagnetic to nonmagnetic at around 3 monolayer thickness, consistent with previous magnetization and magneto-optical Kerr effect measurements. The orbital magnetic moment perpendicular to the film was found to be ˜0.1 μB/Ru , and remained nearly unchanged with decreasing film thickness while the spin magnetic moment decreases. A mechanism for the formation of the orbital magnetic moment is discussed based on the electronic structure of the compressively strained SRO film.
Determination of the Magnetic Moment with Spherical Measurements and Spherical Harmonics Modelling
NASA Astrophysics Data System (ADS)
Dumond, O.; Bergé, R.
2012-05-01
The magnetic moment of space equipment is a needed input for spacecraft magnetic budgeting. In general, a maximum value is also specified. Most of the time, due to the complexity of the equipment, the accurate determination of this magnetic global dipole moment is not possible by analysis. The magnetic sources that compose an equipment can be numerous and of various natures (actuators, current loops in circuits and wires, components, etc.). An experimental determination of the magnetic moment is then necessary. The basic method of the "6 faces" is not adapted for complex equipment (i.e. composed of several elementary dipoles). Intespace and CNES have experimented in the CNES magnetic test facility a method of determination of the magnetic moment using spherical measurements and spherical harmonics modelling. This method has been validated with simulation results and measurements on an assembly of 3 magnets. This paper will also compare the results obtained with other methods of magnetic moment determination. Another advantage of this method is to allow the measurement close to the equipment and then extrapolate the field at another higher distance.
Detmold, W.; Tiburzi, B. C.; Walker-Loud, A.
2010-03-01
Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. This is analogous to the experimental situation, for which determination of polarizabilities from the Compton amplitude requires subtraction of Born terms. With the background field method, we devise combinations of nucleon correlation functions in constant electric fields that isolate magnetic moments and electric polarizabilities. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how both observables can be determined from lattice QCD simulations in background electric fields. We obtain results for the neutron and proton, however, our study is currently limited to electrically neutral sea quarks. The value we extract for the nucleon isovector magnetic moment is comparable to those obtained from measuring lattice three-point functions at similar pion masses.
NASA Astrophysics Data System (ADS)
Kholmetskii, A. L.; Missevitch, O. V.; Yarman, T.
2016-09-01
We consider the relativistic transformation of the magnetic dipole moment and disclose its physical meaning, shedding light on the related difficulties in the physical interpretation of classical electrodynamics in material media.
Robust magnetic moments on the basal plane of the graphene sheet effectively induced by OH groups
NASA Astrophysics Data System (ADS)
Tang, Tao; Tang, Nujiang; Zheng, Yongping; Wan, Xiangang; Liu, Yuan; Liu, Fuchi; Xu, Qinghua; Du, Youwei
2015-02-01
Inducing robust magnetic moments on the basal plane of the graphene sheet is very difficult, and is one of the greatest challenges in the study of physical chemistry of graphene materials. Theoretical studies predicted that introduction of a kind of sp3-type defects formed by OH groups is an effective pathway to achieve this goal [Boukhvalov, D. W. & Katsnelson, M. I. ACS Nano 5, 2440-2446 (2011)]. Here we demonstrate that OH groups can efficiently induce robust magnetic moments on the basal plane of the graphene sheet. We show that the inducing efficiency can reach as high as 217 μB per 1000 OH groups. More interestingly, the magnetic moments are robust and can survive even at 900°C. Our findings highlight the importance of OH group as an effective sp3-type candidate for inducing robust magnetic moments on the basal plane of the graphene sheet.
Electric Quadrupole and Magnetic Dipole Moments of Mirror Nuclei and Self-Conjugate Nuclei
NASA Astrophysics Data System (ADS)
Zickendraht, W.
A transformation, which brings about the unification of the nuclear collective and single particle models, yields sumrules for the magnetic dipole moments and for the electric quadrupole moments of mirror nuclei. These sumrules are applied to cases, for which the numerical values of these moments are known.Translated AbstractElektrische Qadrupol- und Magnetische Dipolmomente von Spiegelkernen und Kernen mit N = ZMit Hilfe einer Transformation, die die Vereinigung von Kollektiv- und Schalenmodell liefert, lassen sich Summenregeln für die magnetischen Dipol- und die elektrischen Quadrupolmomente von Spiegelkernen ableiten. Diese Summenregeln werden auf Spiegelkerne angewandt, für die die numerischen Werte der Momente bekannt sind.
NASA Astrophysics Data System (ADS)
Gómez, A. M.; Torres, D. A.
2016-07-01
The experimental study of nuclear magnetic moments, using the Transient Field technique, makes use of spin-orbit hyperfine interactions to generate strong magnetic fields, above the kilo-Tesla regime, capable to create a precession of the nuclear spin. A theoretical description of such magnetic fields is still under theoretical research, and the use of parametrizations is still a common way to address the lack of theoretical information. In this contribution, a review of the main parametrizations utilized in the measurements of Nuclear Magnetic Moments will be presented, the challenges to create a theoretical description from first principles will be discussed.
Gómez, A. M.; Torres, D. A.
2016-07-07
The experimental study of nuclear magnetic moments, using the Transient Field technique, makes use of spin-orbit hyperfine interactions to generate strong magnetic fields, above the kilo-Tesla regime, capable to create a precession of the nuclear spin. A theoretical description of such magnetic fields is still under theoretical research, and the use of parametrizations is still a common way to address the lack of theoretical information. In this contribution, a review of the main parametrizations utilized in the measurements of Nuclear Magnetic Moments will be presented, the challenges to create a theoretical description from first principles will be discussed.
Heo, Jae Ho
2009-08-01
The model (Lagrangian) with a peculiar extra U(1)[S. M. Barr and I. Dorsner, Phys. Rev. D 72, 015011 (2005); S. M. Barr and A. Khan, Phys. Rev. D 74, 085023 (2006)] is clearly presented. The assigned extra U(1) gauge charges give a strong constraint to build Lagrangians. The Z{sup '} discovery limits are estimated and predicted at the Tevatron and the LHC. The new contributions of the muon anomalous magnetic moment are investigated at one and two loops, and we predict that the deviation from the standard model may be explained. The electron electric dipole moment could also be generated because of the explicit CP-violation effect in the Higgs sector, and a sizable contribution is expected for a moderately sized CP phase [argument of the CP-odd Higgs], 0.1{<=}sin{delta}{<=}1[6 deg. {<=}arg(A){<=}90 deg.].
Origin of the giant magnetic moment in epitaxial Fe3O4 thin films
NASA Astrophysics Data System (ADS)
Orna, J.; Algarabel, P. A.; Morellón, L.; Pardo, J. A.; de Teresa, J. M.; López Antón, R.; Bartolomé, F.; García, L. M.; Bartolomé, J.; Cezar, J. C.; Wildes, A.
2010-04-01
We study the enhanced magnetic moment observed in epitaxial magnetite (Fe3O4) ultrathin films (t<15nm) grown on MgO (001) substrates by means of pulsed laser deposition. The Fe3O4 (001) thin films exhibit high crystallinity, low roughness, and sharp interfaces with the substrate, and the existence of the Verwey transition at thicknesses down to 4 nm. The evolution of the Verwey transition temperature with film thickness shows a dependence with the antiphase boundaries density. Superconducting quantum interference device (SQUID) and vibrating sample magnetometry measurements in ultrathin films show a magnetic moment much higher than the bulk magnetite value. In order to study the origin of this anomalous magnetic moment, polarized neutron reflectivity (PNR), and x-ray magnetic circular dichroism (XMCD) experiments have been performed, indicating a decrease in the magnetization with decreasing sample thickness. X-ray photoemission spectroscopy measurements show no metallic Fe clusters present in the magnetite thin films. Through inductively coupled plasma mass spectroscopy and SQUID magnetometry measurements performed in commercial MgO (001) substrates, the presence of Fe impurities embedded within the substrates has been observed. Once the substrate contribution has been corrected, a decrease in the magnetic moment of magnetite thin films with decreasing thickness is found, in good agreement with the PNR and XMCD measurements. Our experiments suggest that the origin of the enhanced magnetic moment is not intrinsic to magnetite but due to the presence of Fe impurities in the MgO substrates.
Kapitza problem for the magnetic moments of synthetic antiferromagnetic systems
Dzhezherya, Yu. I.; Demishev, K. O.; Korenivskii, V. N.
2012-08-15
The dynamics of magnetization in synthetic antiferromagnetic systems with the magnetic dipole coupling in a rapidly oscillating field has been examined. It has been revealed that the system can behave similar to the Kapitza pendulum. It has been shown that an alternating magnetic field can be efficiently used to control the magnetic state of a cell of a synthetic antiferromagnet. Analytical relations have been obtained between the parameters of such an antiferromagnet and an external magnetic field at which certain quasistationary states are implemented.
Neutrino-antineutrino transitions
Langacker, P.; Wang, J.
1998-11-01
We consider transitions between neutrinos and antineutrinos in laboratory experiments in five scenarios. These include the case in which the helicity flips, producing an antineutrino with normal weak interactions, and helicity preserving oscillations into an SU(2) singlet state which only interacts by mixing or new interactions. The ratio of {mu}{sup +} and {mu}{sup {minus}} events for a high energy {nu}{sub {mu}} beam from pion decay rescattered from a nucleon target and the ratio between e{sup +} and e{sup {minus}} events for a rescattered low energy {nu}{sub e} beam are calculated in each case. The upper limit on the ratio is about 10{sup {minus}6}{endash}10{sup {minus}10} for a high energy {nu}{sub {mu}} beam and 10{sup {minus}6}{endash}10{sup {minus}14} for a low energy {nu}{sub e} beam, too small to observe in present experiments. {copyright} {ital 1998} {ital The American Physical Society}
NASA Astrophysics Data System (ADS)
Feng, Yinglong; Liu, Jinming; Klein, Todd; Wu, Kai; Wang, Jian-Ping
2017-09-01
This report introduces a local-magnetic-reversal-nucleation based giant magnetoresistance (GMR) sensor with a large sensing area and further discusses its novel sensing scheme of high magnetic moment nanoparticles (MNPs). We demonstrated experimentally that this large-area GMR sensor could successfully detect high moment MNPs. The detection scheme of localized reversal nucleation of GMR sensor induced by MNPs was analyzed and further confirmed by the micromagnetic simulations. This work may provide one pathway in designing next generation GMR biosensors with large area and high sensitivity. This sensing scheme could be applicable to other magnetic biosensors such as magnetic tunnel junction sensors and planar Hall sensors.
Koide, T; Miyauchi, H; Okamoto, J; Shidara, T; Fujimori, A; Fukutani, H; Amemiya, K; Takeshita, H; Yuasa, S; Katayama, T; Suzuki, Y
2001-12-17
The spin, in-plane and out-of-plane orbital and magnetic dipole moments of almost purely interfacial Co atoms were directly determined for Au/2-monolayer Co nanoclusters/Au(111) by angle-dependent magnetic circular x-ray dichroism (MCXD) measurements. The field- and temperature-dependent MCXD evidences a ferromagnetic(FM)-to-superparamagnetic phase transition in single-domain clusters with decreasing size. The interfacial moments are remarkably enhanced as compared with bulk values, verifying theoretical predictions. The FM clusters show strong perpendicular magnetic anisotropy, providing promise of applications for nanoscale magnetic bits.
Magnetization reversal of uncompensated Fe moments in exchangebiased Ni/FeF2 bilayers
Arenholz, Elke; Liu, Kai; Li, Zhipan; Schuller, Ivan K.
2006-01-01
The magnetization reversal of uncompensated Fe moments in exchange biased Ni/FeF{sub 2} bilayers was determined using soft x-ray magnetic circular and linear dichroism. The hysteresis loops resulting from the Fe moments are almost identical to those of the ferromagnetic Ni layer. However, a vertical loop shift indicates that some Fe moments are pinned in the antiferromagnetically ordered FeF{sub 2}. The pinned moments are oriented antiparallel to small cooling fields leading to negative exchange bias, but parallel to large cooling fields resulting in positive exchange bias. No indication for the formation of a parallel antiferromagnetic domain wall in the FeF{sub 2} layer upon magnetization reversal in the Ni layer was found.
Antineutrino monitoring of thorium reactors
NASA Astrophysics Data System (ADS)
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-01
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed 233U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of 233U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg of 233U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of 233U could not be detected within the current IAEA timeliness detection goal using either tests. A rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.
Antineutrino monitoring of thorium reactors
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-30
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed ^{233}U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of ^{233}U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg of ^{233}U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of ^{233}U could not be detected within the current IAEA timeliness detection goal using either tests. In conclusion, a rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.
Antineutrino monitoring of thorium reactors
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-30
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed 233U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of 233U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg ofmore » 233U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of 233U could not be detected within the current IAEA timeliness detection goal using either tests. In conclusion, a rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.« less
Antineutrino monitoring of thorium reactors
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-30
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed ^{233}U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of ^{233}U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg of ^{233}U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of ^{233}U could not be detected within the current IAEA timeliness detection goal using either tests. In conclusion, a rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.
Antineutrino monitoring of thorium reactors
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-28
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed ^{233}U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of ^{233}U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg of ^{233}U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of ^{233}U could not be detected within the current IAEA timeliness detection goal using either tests. A rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.
Antineutrino monitoring of thorium reactors
Akindele, Oluwatomi A.; Bernstein, Adam; Norman, Eric B.
2016-09-28
Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuel types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors breed 233U, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of 233U has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg ofmore » 233U, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos at a 25 m standoff. It was found that the diversion of a significant quantity of 233U could not be detected within the current IAEA timeliness detection goal using either tests. A rate-time based analysis exceeded the timeliness goal by 23 days, while a spectral based analysis exceeds this goal by 31 days.« less
Magnetic moments of chromium-doped gold clusters: the Anderson impurity model in finite systems.
Hirsch, K; Zamudio-Bayer, V; Langenberg, A; Niemeyer, M; Langbehn, B; Möller, T; Terasaki, A; Issendorff, B V; Lau, J T
2015-02-27
The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy, charge transfer multiplet calculation, and density functional theory study of size-selected free chromium-doped gold clusters. The observed size dependence of the local magnetic moment can be understood as a transition from a local moment to a mixed valence regime. This shows that the Anderson impurity model essentially describes finite systems even though the discrete density of states introduces a significant deviation from a bulk metal, and the free electron gas is only formed by less than 10 electrons. Electronic shell closure in the gold host minimizes the interaction of localized impurity states with the confined free electron gas and preserves the magnetic moment of 5 μ_{B} fully in CrAu_{2}^{+} and almost fully in CrAu_{6}^{+}. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas stabilizes the local magnetic moment of the impurity atom.
Direct high-precision measurement of the magnetic moment of the proton.
Mooser, A; Ulmer, S; Blaum, K; Franke, K; Kracke, H; Leiteritz, C; Quint, W; Rodegheri, C C; Smorra, C; Walz, J
2014-05-29
One of the fundamental properties of the proton is its magnetic moment, µp. So far µp has been measured only indirectly, by analysing the spectrum of an atomic hydrogen maser in a magnetic field. Here we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in terms of the nuclear magneton: μp = 2.792847350(9)μN. This measurement outperforms previous Penning-trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty-year-old indirect measurement, in which significant theoretical bound state corrections were required to obtain µp, by a factor of 3. By application of this method to the antiproton magnetic moment, the fractional precision of the recently reported value can be improved by a factor of at least 1,000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons.
Direct high-precision measurement of the magnetic moment of the proton
NASA Astrophysics Data System (ADS)
Mooser, A.; Ulmer, S.; Blaum, K.; Franke, K.; Kracke, H.; Leiteritz, C.; Quint, W.; Rodegheri, C. C.; Smorra, C.; Walz, J.
2014-05-01
One of the fundamental properties of the proton is its magnetic moment, µp. So far µp has been measured only indirectly, by analysing the spectrum of an atomic hydrogen maser in a magnetic field. Here we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in terms of the nuclear magneton: μp = 2.792847350(9)μN. This measurement outperforms previous Penning-trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty-year-old indirect measurement, in which significant theoretical bound state corrections were required to obtain µp, by a factor of 3. By application of this method to the antiproton magnetic moment, the fractional precision of the recently reported value can be improved by a factor of at least 1,000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons.
Optically induced interaction of magnetic moments in hybrid metamaterials.
Miroshnichenko, Andrey E; Luk'yanchuk, Boris; Maier, Stefan A; Kivshar, Yuri S
2012-01-24
We propose a novel type of hybrid metal-dielectric structures composed of silicon nanoparticles and split-ring resonators for advanced control of optically induced magnetic response. We reveal that a hybrid "metamolecule" may exhibit a strong distance-dependent magnetic interaction that may flip the magnetization orientation and support "antiferromagnetic" ordering in a hybrid metamaterial created by a periodic lattice of such metamolecules. The propagation of magnetization waves in the hybrid structures opens new ways for manipulating artificial "antiferromagnetic" ordering at high frequencies. © 2011 American Chemical Society
Quantum aspects of a moving magnetic quadrupole moment interacting with an electric field
Fonseca, I. C.; Bakke, K.
2015-06-15
The quantum dynamics of a moving particle with a magnetic quadrupole moment that interacts with electric and magnetic fields is introduced. By dealing with the interaction between an electric field and the magnetic quadrupole moment, it is shown that an analogue of the Coulomb potential can be generated and bound state solutions can be obtained. Besides, the influence of the Coulomb-type potential on the harmonic oscillator is investigated, where bound state solutions to both repulsive and attractive Coulomb-type potentials are achieved and the arising of a quantum effect characterized by the dependence of the harmonic oscillator frequency on the quantum numbers of the system is discussed.
Orbital magnetic moment in Ir doped CaMnO(3).
Mizusaki, S; Toyoda, Y; Ohnishi, T; Nagata, Y; Itou, M; Sakurai, Y; Noro, Y; Ozawa, T C
2009-08-19
The magnetism of CaMn(0.55)Ir(0.45)O(3) has been studied using the magnetic Compton scattering technique. The analysis of the magnetic Compton profile shows that the spin moments of Mn and Ir form an antiparallel configuration, establishing ferrimagnetism. Moreover, the experimental results indicate the existence of an orbital moment 0.2 μ(B)/f.u.. The possible model for these results has been discussed under the framework of the localized electron model by taking account of the electronic states of the Ir(4+) ion.
Precise determination of magnetic moment of a fluxoid quantum in a superconducting microring
NASA Astrophysics Data System (ADS)
Choi, Heonhwa; Kim, Yun Won; Lee, Soon-Gul; Choi, Mahn-Soo; Kim, Min-Seok; Choi, Jae-Hyuk
2017-02-01
Using dynamic cantilever magnetometry and experimentally determining the cantilever's vibrational mode shape, we precisely measured the magnetic moment of a lithographically defined micron-sized superconducting Nb ring, a key element for the previously proposed subpiconewton force standard. The magnetic moments due to individual magnetic fluxoids and a diamagnetic response were independently determined at T =4.3 K, with a subfemtoampere-square-meter resolution. The results show good agreement with the theoretical estimation yielded by the Brandt and Clem model within the spring constant determination accuracy.
Park, Jooneon; Porter, Marc D; Granger, Michael C
2017-06-14
Magnetic particles are widely used as labels in magnetoresistive sensors. To use magnetic particles as labels, several important characteristics should be considered, such as superparamagnetism, a high magnetic moment per particle (m), facile surface functionalization and biomolecule immobilization, colloidal stability, and analyte specificity. In this paper, we describe the preparation of magnetic labels with a high m, using colloidal assemblies of superparamagnetic zinc ferrite nanoparticles (ZFNPs, ∼9 nm). Also, several properties of these particles are compared with those of commercially available magnetic beads, Dynabeads and TurboBeads. The colloidally assembled zinc ferrite magnetic beads (ZFMBs, ∼160 nm) were synthesized by assembling ZFNPs via an emulsion-based assembly approach. While retaining superparamagnetism at room temperature, the m of ZFMBs is ∼4000× higher than that of the constituent ZFNPs. Surface functionalization with a layer of polyacrylic acid stabilized the ZFMBs in aqueous solution and enabled conjugation with streptavidin via carbodiimide linking chemistry. The streptavidinated ZFMBs can be suspended in aqueous buffer for ≥24 h, whereas 1.05 μm Dynabeads and 30 nm TurboBeads undergo ballistic deposition and instantaneous aggregation in solution, respectively. Finally, the streptavidinated ZFMBs were employed as labels in an immunoassay for the detection of osteopontin, a potential pancreatic cancer marker, proving superior to the commercial particles in terms of limit of detection and dynamic range. We expect that the work presented in this article can be extended to other biological applications, especially where superparamagnetic particles with a high m and colloidal stability are needed.
Tang, Jiqiang; Xiang, Biao; Zhang, Yongbin
2014-07-01
For a magnetically suspended control moment gyroscope, stiffness and damping of magnetic bearing will influence modal frequency of a rotor. In this paper the relationship between modal frequency and stiffness and damping has been investigated. The mathematic calculation model of axial passive magnetic bearing (PMB) stiffness is developed. And PID control based on internal model control is introduced into control of radial active magnetic bearing (AMB), considering the radial coupling of axial PMB, a mathematic calculation model of stiffness and damping of radial AMB is established. According to modal analysis, the relationship between modal frequency and modal shapes is achieved. Radial vibration frequency is mainly influenced by stiffness of radial AMB; however, when stiffness increases, radial vibration will disappear and a high frequency bending modal will appear. Stiffness of axial PMB mainly affects the axial vibration mode, which will turn into high-order bending modal. Axial PMB causes bigger influence on torsion modal of the rotor.
Segmented scintillation antineutrino detector
Reyna, David
2017-05-09
The various technologies presented herein relate to incorporating a wavelength-shifting material in a scintillator to facilitate absorption of a first electromagnetic particle (e.g., a first photon) having a first wavelength and subsequent generation and emission of a second electromagnetic particle (e.g., a second photon) having a second wavelength. The second electromagnetic particle can be emitted isotropically, with a high probability that the direction of emission of the second electromagnetic particle is disparate to the direction of travel of the first electromagnetic particle (and according angle of incidence). Isotropic emission of the second electromagnetic particle enables the second electromagnetic particle to be retained in the scintillator owing to internal reflection. Accordingly, longer length scintillators can be constructed, and accordingly, the scintillator array has a greater area (and volume) over which to detect electromagnetic particles (e.g., antineutrinos) being emitted from a nuclear reaction.
Magnetic moment of a single metal nanoparticle determined from the Faraday effect
NASA Astrophysics Data System (ADS)
Szczytko, Jacek; Vaupotič, Nataša; Madrak, Karolina; Sznajder, Paweł; Górecka, Ewa
2013-03-01
Optical properties of a composite material made of ferromagnetic metal nanoparticles embedded in a dielectric host are studied. We constructed an effective dielectric tensor of the composite material taking into account the orientational distribution of nanoparticle magnetic moments in external magnetic field. A nonlinear dependence of the optical rotation on magnetic field resulting from the reorientation of nanoparticles is demonstrated. The theoretical findings were applied to the magneto-optical experimental data of cobalt ferromagnetic nanoparticles embedded in a dielectric liquid host. The dependence of the Faraday rotation on Co-based ferromagnetic nanoparticles was measured as a function of the external magnetic field, varying the size of nanoparticles and the wavelength of light. The proposed approach enables quantitative determination of the magnetic moment and the plasma frequency of a single nanoparticle, and from this the size of the nonmagnetic shell of magnetic nanoparticles.
Phase formation, thermal stability and magnetic moment of cobalt nitride thin films
Gupta, Rachana; Pandey, Nidhi; Tayal, Akhil; Gupta, Mukul E-mail: dr.mukul.gupta@gmail.com
2015-09-15
Cobalt nitride (Co-N) thin films prepared using a reactive magnetron sputtering process are studied in this work. During the thin film deposition process, the relative nitrogen gas flow (R{sub N{sub 2}}) was varied. As R{sub N{sub 2}} increases, Co(N), Co{sub 4}N, Co{sub 3}N and CoN phases are formed. An incremental increase in R{sub N{sub 2}}, after emergence of Co{sub 4}N phase at R{sub N{sub 2}} = 10%, results in a linear increase of the lattice constant (a) of Co{sub 4}N. For R{sub N{sub 2}} = 30%, a maximizes and becomes comparable to its theoretical value. An expansion in a of Co{sub 4}N, results in an enhancement of the magnetic moment, to the extent that it becomes even larger than pure Co. Such larger than pure metal magnetic moment for tetra-metal nitrides (M{sub 4}N) have been theoretically predicted. Incorporation of N atoms in M{sub 4}N configuration results in an expansion of a (relative to pure metal) and enhances the itinerary of conduction band electrons leading to larger than pure metal magnetic moment for M{sub 4}N compounds. Though a higher (than pure Fe) magnetic moment for Fe{sub 4}N thin films has been evidenced experimentally, higher (than pure Co) magnetic moment is evidenced in this work.
Aharonov–Anandan quantum phases and Landau quantization associated with a magnetic quadrupole moment
Fonseca, I.C.; Bakke, K.
2015-12-15
The arising of geometric quantum phases in the wave function of a moving particle possessing a magnetic quadrupole moment is investigated. It is shown that an Aharonov–Anandan quantum phase (Aharonov and Anandan, 1987) can be obtained in the quantum dynamics of a moving particle with a magnetic quadrupole moment. In particular, it is obtained as an analogue of the scalar Aharonov–Bohm effect for a neutral particle (Anandan, 1989). Besides, by confining the quantum particle to a hard-wall confining potential, the dependence of the energy levels on the geometric quantum phase is discussed and, as a consequence, persistent currents can arise from this dependence. Finally, an analogue of the Landau quantization is discussed. -- Highlights: •Scalar Aharonov–Bohm effect for a particle possessing a magnetic quadrupole moment. •Aharonov–Anandan quantum phase for a particle with a magnetic quadrupole moment. •Dependence of the energy levels on the Aharonov–Anandan quantum phase. •Landau quantization associated with a particle possessing a magnetic quadrupole moment.
Magnetic moments and g-factors in odd-A Ho isotopes
NASA Astrophysics Data System (ADS)
Tabar, E.; Yakut, H.; Kuliev, A. A.; Quliyev, H.; Hocşgör, G.
2017-07-01
The ground-state magnetic moment, g K factor and quenching spin gyromagnetic ratio have been calculated using the microscopic method based on the Quasiparticle Phonon Nuclear Model (QPNM) for 155-169Ho nuclei for the first time. It is shown that the residual spin-spin interactions are responsible for the core polarization, and because of the core polarization the spin gyromagnetic factors are quenched. By considering the core polarization effects, a satisfactory agreement is obtained for the computed ground state g K factor, which gives an intrinsic contribution to the magnetic moments. In order to assess the collective contribution to the magnetic moments, the rotational gyromagnetic factors g R have been also calculated within the cranking approximation using the single particle wave function of the axially symmetric Woods-Saxon potential. For the ground-state magnetic moments of odd-proton 155-165Ho nuclei, a good description of the experimental data is obtained with an accuracy of 0.01-0.1 μ N. From systematic trends, the quenching spin gyromagnetic factor, g K factor and magnetic moment have also been theoretically predicted for 167,169Ho where there is no existing experimental data. Supported by Scientific and Technological Research Council of Turkey (TUBITAK) (115F564)
EM Induction Experiment to Determine the Moment of a Magnet
ERIC Educational Resources Information Center
Najiya Maryam, K. M.
2014-01-01
If we drop a magnet through a coil, an emf is induced in the coil according to Faraday's law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets.…
EM Induction Experiment to Determine the Moment of a Magnet
ERIC Educational Resources Information Center
Najiya Maryam, K. M.
2014-01-01
If we drop a magnet through a coil, an emf is induced in the coil according to Faraday's law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets.…
Magnetic moments in chemically ordered mass-selected CoPt and FePt clusters
NASA Astrophysics Data System (ADS)
Dupuis, V.; Khadra, G.; Linas, S.; Hillion, A.; Gragnaniello, L.; Tamion, A.; Tuaillon-Combes, J.; Bardotti, L.; Tournus, F.; Otero, E.; Ohresser, P.; Rogalev, A.; Wilhelm, F.
2015-06-01
By combining high photon flux and chemical selectivity, X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) have been used to study the magnetism of CoPt and FePt clusters before and after their transition to the chemically ordered L10-like phase. Compared to the bulk, we find larger magnetic spin and orbital moments of Fe, Co and Pt atoms in nanoalloys.
Orbital magnetic moment instability at the spin reorientation transition of Nd2Fe14B
Garcia; Chaboy; Bartolome; Goedkoop
2000-07-10
Highly accurate soft-XMCD data recorded on a Nd2Fe14B single crystal, through the spin reorientation transition show that the average Fe orbital moment (a) is proportional to the macroscopic Fe anisotropy constant, and (b) diverges 15 K below the reorientation transition temperature. This divergence is indicative of a critical behavior and it is related to a tetragonal distortion. These results give experimental evidence of the mutual dependence between orbital moment, macroscopic magnetic anisotropy, and tetragonal distortion. Furthermore, it is argued that the critical behavior of the orbital moment is at the origin of similar divergences previously observed in Mossbauer and Hall-effect data.
Steady-state solutions for atomic multipole moments in an arbitrarily oriented static magnetic field
NASA Astrophysics Data System (ADS)
Bevilacqua, G.; Breschi, E.; Weis, A.
2014-03-01
We derive algebraic expressions for the atomic multipole moments mk ,q(F) describing the steady-state polarization of an atomic ensemble with angular momentum F in a static magnetic field of arbitrary direction and general multipole relaxation rates Γq(k). The longitudinal moments mk ,0 are given in terms of truncated continued fractions, while the transverse moments mk ,q≠0, representing the ensemble coherence, are given by products of truncated continued fractions. The special case of isotropic relaxation leads to particularly simple and elegant expressions. Our results are relevant for all domains of physics that consider the evolution of a spin system interacting with vector-type perturbations.
Localized magnetic moments in the Heusler alloy Rh2MnGe
NASA Astrophysics Data System (ADS)
Klaer, P.; Kallmayer, M.; Elmers, H. J.; Basit, L.; Thöne, J.; Chadov, S.; Felser, C.
2009-04-01
X-ray magnetic circular dichroism (XMCD) of core-level absorption (x-ray absorption spectroscopy, XAS) spectra in the soft x-ray region has been measured for the ferromagnetic Heusler alloy Rh2MnGe at the Rh M3,2 and Mn L3,2 edges. The ratio of Rh and Mn spin moments amounts to 0.05 which is smaller than the ratio of 0.1 determined by a local density approximation electronic band structure calculation. We have found that the orbital moments of the Rh 4d and Mn 3d states are very small. The observed Rh 2p XAS spectrum can be understood on the basis of the Rh 3d partial density of unoccupied states as is typical for metals. The observed features of the Mn 2p XAS and XMCD spectra are dominated by final state multiplets as is typical for oxides. The comparison of experimental and ab initio calculated XAS/XMCD spectra reveals a strong narrowing of the Mn 3d bands, indicating strongly localized Mn moments. The magnetic moments are considerably more localized for Rh2MnGe in comparison with the isoelectronic compound Co2MnGe. In spite of the strong localization of the Mn moment, the temperature dependences of sublattice magnetization are equal for the Mn and Rh sublattices in contrast to the prediction by a Heisenberg model. This might be attributed to the remaining itinerant character of the Rh moment.
Phenomenology of the new physics coming from 2HDMs to the neutrino magnetic dipole moment
NASA Astrophysics Data System (ADS)
Tarazona, Carlos G.; Diaz, Rodolfo A.; Morales, John; Castillo, Andrés
2017-04-01
In several frameworks for leptons sectors of Two Higgs Doublet Models, we calculate the magnetic dipole moment for different flavor types of neutrino. Computations are carried out by assuming a normal hierarchy for neutrino masses, and analyzing the process ν → νγ with a charged Higgs boson into the loop. The analysis was performed by sweeping the charged Higgs mass and taking into account the experimental constraints for relevant parameters in Two Higgs Doublet Models with and without flavor changing neutral currents; obtaining magnetic dipole moments close to the experimental thresholds for tau neutrinos in type II and lepton-specific cases. In the neutrino-specific scenario, the contribution of new physics could be sizeable to the current measurement for flavor magnetic dipole moment. This fact leads to excluding possible zones in the parameter space of charged Higgs mass and vacuum expectation value of the second doublet.
Neutral current induced {pi}{sup 0} production and neutrino magnetic moment
Athar, M. Sajjad; Chauhan, S.; Singh, S. K.
2008-08-01
We have studied the total cross section, Q{sup 2}, momentum and angular distributions for pions in the {nu}({nu}) induced {pi}{sup 0} production from nucleons. The calculations have been done for the weak production induced by the neutral current in the standard model and the electromagnetic production induced by neutrino magnetic moment. It has been found that with the present experimental limits on the muon neutrino magnetic moment {mu}{sub {nu}{sub {mu}}}, the electromagnetic contribution to the cross section for the {pi}{sup 0} production is small. The neutrino induced neutral current production of {pi}{sup 0}, while giving an alternative method to study the magnetic moment of neutrino {mu}{sub {nu}{sub {mu}}}, does not provide any improvement over the present experimental limit on {mu}{sub {nu}{sub {mu}}} from the observation of this process in future experiments at T2K and NO{nu}A.
Nuclear Structure and Magnetic Moment of the Unstable 12B-12N Mirror Pair
NASA Astrophysics Data System (ADS)
Zheng, Yong-Nan; Zhou, Dong-Mei; Yuan, Da-Qing; Zuo, Yi; Fan, Ping; Mihara, M.; Matsuta, K.; Fukuda, M.; Minamisono, T.; Suzuki, T.; Xu, Yong-Jun; Zhu, Jia-Zheng; Wang, Zhi-Qiang; Luo, Hai-Long; Zhang, Xi-Zhen; Zhu, Sheng-Yun
2010-02-01
Magnetic moments of the A = 12 unstable mirror pair nuclides 12B and 12N have been measured by the β- NMR, technique. The experimentally measured magnetic moments are μ(12B) = 1.001(17)μN and μ(12N) = 0.4571(1)μN The improved shell model using an SFO Hamiltonian with enhanced spin-isospin monopole proton-neutron interaction and modified single-particle energies is employed to calculate the magnetic moments of 12B and 12N. The calculation yields μ(12B) = 0.929μN and μ(12N) = 0.452μN and has produced a new magic number 6 for the short-lived unstable mirror pair nuclides 12B and 12N.
Bohm, A.; Kielanowski, P.
1983-06-01
We have performed a test of the conserved-vector-current hypothesis (CVC) by determining the baryon charges and magnetic moments from the hyperon semileptonic data. Then CVC was applied in order to make a joint fit of all baryon semileptonic decay data and baryon magnetic moments for the spectrum-generating-group (SG) model as well as for the conventional (Cabibbo and magnetic moments in nuclear magnetons) model. The SG model gives a very good fit with chi/sup 2//n/sub D/ = 25/20/sup triangle-open//sub 21% C.L. whereas the conventional model gives a fit with chi/sup 2//n/sub D/approx. =244/20.
Aharonov-Bohm scattering of relativistic Dirac particles with an anomalous magnetic moment
Lin Qionggui
2005-10-15
The Aharonov-Bohm scattering of relativistic spin-1/2 particles with an anomalous magnetic moment are studied. The scattering cross sections for unpolarized and polarized particles are obtained by solving the Dirac-Pauli equation. It is somewhat unexpected that the results are in general the same as those for particles without an anomalous magnetic moment. However, when the incident energy takes some special values, the cross section for polarized particles is dramatically changed. In these cases the helicity of scattered particles is not conserved. In particular, the helicity of particles scattered in the backward direction is all reversed. In the nonrelativistic limit, a very simple relation between the polarized directions of the incident and scattered particles is found, for both general and special incident energies. For particles without an anomalous magnetic moment this relation can be drawn from previous results but it appears to be unnoticed.
Towards a high-precision measurement of the antiproton magnetic moment
NASA Astrophysics Data System (ADS)
Smorra, C.; Blaum, K.; Franke, K.; Matsuda, Y.; Mooser, A.; Nagahama, H.; Ospelkaus, C.; Quint, W.; Schneider, G.; Van Gorp, S.; Walz, J.; Yamazaki, Y.; Ulmer, S.
2014-02-01
The recent observation of single spins flips with a single proton in a Penning trap opens the way to measure the proton magnetic moment with high precision. Based on this success, which has been achieved with our apparatus at the University of Mainz, we demonstrated recently the first application of the so called double Penning-trap method with a single proton. This is a major step towards a measurement of the proton magnetic moment with ppb precision. To apply this method to a single trapped antiproton our collaboration is currently setting up a companion experiment at the antiproton decelerator of CERN. This effort is recognized as the Baryon Antibaryon Symmetry Experiment (BASE). A comparison of both magnetic moment values will provide a stringent test of CPT invariance with baryons.
Egan, R; Philippe, M; Wera, L; Fagnard, J F; Vanderheyden, B; Dennis, A; Shi, Y; Cardwell, D A; Vanderbemden, P
2015-02-01
We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm(3)) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m(2) (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).
NASA Astrophysics Data System (ADS)
Egan, R.; Philippe, M.; Wera, L.; Fagnard, J. F.; Vanderheyden, B.; Dennis, A.; Shi, Y.; Cardwell, D. A.; Vanderbemden, P.
2015-02-01
We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm3) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m2 (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).
Octet and decuplet baryon magnetic moments in the chiral quark model
NASA Astrophysics Data System (ADS)
Dahiya, Harleen; Gupta, Manmohan
2003-06-01
Octet and decuplet baryon magnetic moments have been formulated within the chiral quark model (χ QM) with configuration mixing incorporating the sea quark polarizations and their orbital angular momentum through a generalization of the Cheng-Li mechanism. When the parameters of the χ QM without configuration mixing are fixed by incorporating the latest data pertaining to ū-d¯ asymmetry (E866) and the spin polarization functions, in the case of octet magnetic moments the results not only show improvement over the nonrelativistic quark model results but also give a nonzero value for the right hand side of the Coleman-Glashow sum rule, usually zero in most of the models. In the case of decuplet magnetic moments, we obtain a good overlap for Δ++, Ω-, and the transition magnetic moment ΔN for which data are available. In the case of the octet, the predictions of the χ QM with the generalized Cheng-Li mechanism show remarkable improvements in general when the effects of configuration mixing and “mass adjustments” due to confinement are included, specifically in the case of p, Σ+, Ξ0, and the ΣΛ transition magnetic moment and in the violation of the Coleman-Glashow sum rule an almost perfect agreement with data is obtained. When the above analysis is repeated with the earlier NMC data, a similar level of agreement is obtained; however, the results in the case of E866 look to be better. In this case, we incorporate in our analysis the gluon polarization Δg, found phenomenologically through the relation ΔΣ(Q2)=ΔΣ-[3αs(Q2)/2π]Δg(Q2); not only do we obtain an improvement in the quark spin distribution functions and magnetic moments, but also the value of Δg comes out in good agreement with certain recent measurements as well as theoretical estimates.
Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors.
Kikoin, Konstantin; Drechsler, Stefan-Ludwig; Koepernik, Klaus; Málek, Jiři; van den Brink, Jeroen
2015-07-14
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell.
Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors
Kikoin, Konstantin; Drechsler, Stefan-Ludwig; Koepernik, Klaus; Málek, Jiři; van den Brink, Jeroen
2015-01-01
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell. PMID:26169486
Magnetic moments of baryons containing all heavy quarks in the quark-diquark model
NASA Astrophysics Data System (ADS)
Thakkar, Kaushal; Majethiya, Ajay; Vinodkumar, P. C.
2016-09-01
The triply heavy flavour baryons are studied using the quark-diquark description of the three-body system. The confinement potential for the present study of triply heavy flavour baryons is assumed as Coulomb plus power potential with power index ν. We have solved the Schrödinger equation numerically to calculate the masses of triply heavy flavour baryons. The masses and magnetic moments of triply heavy flavour baryons are computed for different power indices, ν, starting from 0.4 to 1.0. The predicted masses and magnetic moments are in good agreement with other theoretical predictions.
Direct observation of enhanced magnetic moments in Fe/Ag(100)
NASA Astrophysics Data System (ADS)
Wooten, C. L.; Chen, J.; Mulhollan, G. A.; Erskine, J. L.; Markert, J. T.
1994-04-01
The magnetic properties of ultrathin (1-5 monolayer) Fe films on Ag(100) substrates were investigated using SQUID magnetometry. Films were grown in pairs (one bulklike, the other thin), and characterized in situ by low-energy electron diffraction, Auger spectroscopy, and the surface magneto-optic Kerr effect. The films were than capped with Au and studied with a SQUID magnetometer over the temperature range 2-340 K. We report here a direct observation of enhanced magnetic moments for Fe on Ag(100), with interface moments enhanced as much as 29%.
Magnetic moment of proton drip-line nucleus {sup 9}C
Matsuta, K.; Fukuda, M.; Tanigaki, M.; Minamisono, T.; Nojiri, Y.; Mihara, M.; Onishi, T.; Yamaguchi, T.; Harada, A.; Sasaki, M.
1994-10-01
The magnetic moment of the proton drip-line nucleus {sup 9}C(I{sup {pi}}=3/2{sup -}, T{sub {1/2}}=126 ms) has been measured for the first time, using the {beta}-NMR detection technique with polarized radioactive beams. The measured value for the magnetic moment is {vert_bar} {mu}({sup 9}C) {vert_bar} = 1.3914{+-}0.0005 {mu}{sub N}. The deduced spin expectation value<{sigma}> of 1.44 is unusually larger than an other ones of even-odd nuclei.
Prediction of magnetic moment collapse in ZrFe{sub 2} under hydrostatic pressure
Zhang, Wenxu; Zhang, Wanli
2015-04-28
Electronic structure and magnetic properties of ZrFe{sub 2} in the cubic Laves phase are investigated by calculations based on density functional theory. The magnetic moment decreases with the increase of the hydrostatic pressure in an unusual way: Two-step magnetic collapse is predicted. The first one is a continuous change from 1.53 μ{sub B}/Fe to 0.63 μ{sub B}/Fe at about 3.6 GPa, and the other is from 0.25 μ{sub B}/Fe to the nonmagnetic state at about 15 GPa in a first order manner under the local spin density approximation of the exchange correlation potential. A metastable state with intermediate spin moment about 0.15 μ{sub B}/Fe may exist before that. We understand this process by the changes of density of states during it. The magnetic moment decreases under the pressure in the vicinity of the experimental lattice constant with dlnm/dp=−0.038 GPa{sup −1}. The spontaneous volume magnetostriction is 3.6%, which is huge enough to find potential applications in magnetostriction actuators and sensors. We suggest that the Invar effect of this compound may be understood when considering the magnetic moment variation according to the magnetostrictive model of Invar.
Stone, N. J.
2015-09-15
The most recent tabulations of nuclear magnetic dipole and electric quadrupole moments have been prepared and published by the Nuclear Data Section of the IAEA, Vienna [N. J. Stone, Report No. INDC(NDS)-0650 (2013); Report No. INDC(NDS)-0658 (2014)]. The first of these is a table of recommended quadrupole moments for all isotopes in which all experimental results are made consistent with a limited number of adopted standards for each element; the second is a combined listing of all measurements of both moments. Both tables cover all isotopes and energy levels. In this paper, the considerations relevant to the preparation of both tables are described, together with observations as to the importance and (where appropriate) application of necessary corrections to achieve the “best” values. Some discussion of experimental methods is included with emphasis on their precision. The aim of the published quadrupole moment table is to provide a standard reference in which the value given for each moment is the best available and for which full provenance is given. A table of recommended magnetic dipole moments is in preparation, with the same objective in view.
Magnetic dipole moment of the doubly-closed-shell plus one proton nucleus 49Sc.
Ohtsubo, T; Stone, N J; Stone, J R; Towner, I S; Bingham, C R; Gaulard, C; Köster, U; Muto, S; Nikolov, J; Nishimura, K; Simpson, G S; Soti, G; Veskovic, M; Walters, W B; Wauters, F
2012-07-20
The nucleus 49Sc, having a single f(7/2) proton outside doubly magic 48Ca (Z=20, N=28), is one of the very few isotopes which makes possible testing of the fundamental theory of nuclear magnetism. The magnetic moment has been measured by online β NMR of nuclei oriented at milli-Kelvin temperatures to be (+)5.616(25) μ(N). The result is discussed in terms of a detailed theory of the structure of the magnetic moment operator, showing excellent agreement with calculated departure from the f(7/2) Schmidt limit extreme single-particle value. The measurement completes the sequence of moments of Sc isotopes with even numbers of f(7/2) neutrons: the first such isotopic chain between two major shells for which a full set of moment measurements exists. The result further completes the isotonic sequence of ground-state moments of nuclei with an odd number of f(7/2) protons coupled to a closed subshell of f(7/2) neutrons. Comparison with a recent shell-model calculation of the latter sequence is made.
Disparate ultrafast dynamics of itinerant and localized magnetic moments in gadolinium metal
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
Polaron formation and local magnetic moments in cuprate superconductors
Lorenzana, J. ); Dobry, A. )
1994-12-01
Exact diagonalization calculations show a continuous transition from delocalized to polaron behavior as a function of intersite electron-lattice coupling. A transition, found previously at the Hartree-Fock level between a magnetic and a nonmagnetic state, does not subsist when fluctuations are included. Local phonon modes become softer close to the polaron and by comparison with optical measurements of doped cuprates we conclude that they are close to the transition region between polaronic and nonpolaronic behavior. The barrier to adiabatically move a hole vanishes in that region suggesting large mobilities.
Generation of localized magnetic moments in the charge-density-wave state
NASA Astrophysics Data System (ADS)
Akzyanov, Ramil S.; Rozhkov, Alexander V.
2015-08-01
We propose a mechanism explaining the generation of localized magnetic moments in charge-density-wave compounds. Our model Hamiltonian describes an Anderson impurity placed in a host material exhibiting the charge-density wave. There is a region of the model's parameter space, where even weak Coulomb repulsion on the impurity site is able to localize the magnetic moment on the impurity. The phase diagram of a single impurity at T = 0 is mapped. To establish the connection with experiment, the thermodynamic properties of a random impurity ensemble is studied. Magnetic susceptibility of the ensemble diverges at low temperature; heat capacity as a function of the magnetic field demonstrates pronounced low field peak. Both features are consistent with experiments on orthorhombic TaS3 and blue bronze.
Neutrino Magnetic Moments, Flavor Mixing, and the Super-Kamiokande Solar Data
Beacom, J. F.; Vogel, P.
1999-12-20
We find that magnetic neutrino-electron scattering is unaffected by oscillations for vacuum mixing of Dirac neutrinos with only diagonal moments and for Majorana neutrinos with two flavors. For Mikheyev-Smirnov-Wolfenstein mixing, these cases are again obtained, though the effective moments can depend on the neutrino energy. Thus, e.g., the magnetic moments measured with {nu}(bar sign){sub e} from a reactor and {nu}{sub e} from the Sun could be different. With minimal assumptions, we find a new limit on {mu}{sub {nu}} using the 825-d Super-Kamiokande solar neutrino data: |{mu}{sub {nu}}|{<=}1.5x10{sup -} {sup 10}{mu}{sub B} at 90% CL, comparable to the existing reactor limit. (c) 1999 The American Physical Society.
Direct high-precision measurement of the magnetic moment of the proton
NASA Astrophysics Data System (ADS)
Quint, Wolfgang
2015-05-01
The challenge to measure the properties of the proton with great precision inspires very different branches of physics. The magnetic moment of the proton is a fundamental property of this particle. So far it has only been measured indirectly, by analyzing the spectrum of an atomic hydrogen maser in a magnetic field. Here we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in terms of the nuclear magneton: μp = 2.792 847 350 (9) μN. This measurement outperforms previous Penning-trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty year-old indirect measurement by D. Kleppner et al., in which significant theoretical bound-state corrections were required to obtain μp, by a factor of 3. By application of this method to the antiproton magnetic moment, the fractional precision of the recently reported value can be improved by a factor of at least 1,000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons. Deutsche Forschungsgemeinschaft, grant QU122/3.
Moment Selective Digital Detection of Single Magnetic Beads for Multiplexed Bioassays
NASA Astrophysics Data System (ADS)
Llandro, J.; Hayward, T. J.; Bland, J. A. C.; Morecroft, D.; Castaño, F. J.; Colin, I. A.; Ross, C. A.
2008-06-01
Research into lab-on-a-chip multiplexed bioassays has focused on libraries of biochemical probes, indexed by optically encoded micron-sized labels. However, few current methods have reconciled large multiplexing capability with a rapid detection system amenable to miniaturization. Magnetic identification of labels provides a strong candidate solution to this problem, yet no proposed single-label magnetic detection system can both read and encode magnetic labels. We present a magnetic multiplexed assay in lab-on-a-chip format which identifies target biomolecules from the hybridization results by reading encoded magnetic beads. We show that a microfabricated magnetoresistive ring-shaped sensor can read the magnetic moments of individual commercially available paramagnetic beads using an active digital technique. This work provides proof of principle for a new approach to magnetic labeling of biomolecules for high-throughput bioassays.
The New Result of the Neutrino Magnetic Moment Measurement in the Gemma Experiment
NASA Astrophysics Data System (ADS)
Beda, A. G.; Brudanin, V. B.; Demidova, E. V.; Egorov, V. G.; Gavrilov, M. G.; Shirchenko, M. V.; Starostin, A. S.; Vylov, Ts.
2009-01-01
The new result of the neutrino magnetic moment measurement obtained by the collaboration of the Institute of Theoretical and Experimental Physics (ITEP, Moscow) and the Joint Institute for Nuclear Research (JINR, Dubna) is presented... Note from Publisher: This article contains the abstract and references only.
High-precision evaluation of the magnetic moment of the helion
Neronov, Yu. I. Seregin, N. N.
2012-11-15
NMR spectra of samples containing a mixture of hydrogen deuteride HD with pressure of about 80 atm and helium-3 with partial pressure of about 1 atm are analyzed. The ratio of the resonance frequencies of the nuclei, F({sup 3}He)/F(H{sub 2}), is determined to be 0.761786594(2), which is equal to the magnetic moment of the helion (bound in a helium atom) in the units of the magnetic moment of a proton (bound in molecular hydrogen). The uncertainty of two digits in the last place corresponds to a relative error of {delta}[F({sup 3}He)/F(H{sub 2})] = 2.6 Multiplication-Sign 10{sup -9}. The use of the known calculated data on the shielding of nuclei in the helium-3 atom ({sigma}({sup 3}He) = 59924(2) Multiplication-Sign 10{sup -9}) and on the shielding of protons in hydrogen ({sigma}(H{sub 2}) = 26288(2) Multiplication-Sign 10{sup -9}) yields a value of {mu}({sup 3}He)/{mu}{sub p} = -0.761812217(3) for the free magnetic moment of the helion in the units of the proton magnetic moment.
Nucleon polarizabilities and {Delta}-resonance magnetic moment in chiral EFT
Pascalutsa, Vladimir
2011-10-24
Recent chiral EFT calculations of nucleon polarizabilities reveal a problem in the current empirical determination of proton's electromagnetic polarizabilities. We also report on the progress in the empirical determination of the {Delta}(1232)-resonance magnetic moment in the process of {gamma}p{yields}p{pi}{sup 0}{gamma}' measured at MAMI.
Nucleon polarizabilities and Δ-resonance magnetic moment in chiral EFT
NASA Astrophysics Data System (ADS)
Pascalutsa, Vladimir
2011-10-01
Recent chiral EFT calculations of nucleon polarizabilities reveal a problem in the current empirical determination of proton's electromagnetic polarizabilities. We also report on the progress in the empirical determination of the Δ(1232)-resonance magnetic moment in the process of γp→pπ0γ' measured at MAMI.
Dynamic RKKY interaction between magnetic moments in graphene nanoribbons
NASA Astrophysics Data System (ADS)
Guimarães, F. S. M.; Duffy, J.; Costa, A. T.; Muniz, R. B.; Ferreira, M. S.
2016-12-01
Graphene has been identified as a promising material with numerous applications, particularly in spintronics. In this paper we investigate the peculiar features of spin excitations of magnetic units deposited on graphene nanoribbons and how they can couple through a dynamical interaction mediated by spin currents. We examine in detail the spin lifetimes and identify a pattern caused by vanishing density of states sites in pristine ribbons with armchair borders. Impurities located on these sites become practically invisible to the interaction but can be made accessible by a gate voltage or doping. We also demonstrate that the coupling between impurities can be turned on or off using this characteristic, which may be used to control the transfer of information in transistorlike devices.
NASA Astrophysics Data System (ADS)
Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; Wilhelm, Jonas; Chang, Emmanuel; Detmold, William; Orginos, Kostas
2017-06-01
Lattice QCD calculations with background magnetic fields are used to determine the magnetic moments of the octet baryons. Computations are performed at the physical value of the strange quark mass, and two values of the light quark mass, one corresponding to the S U (3 )F-symmetric point, where the pion mass is mπ˜800 MeV , and the other corresponding to a pion mass of mπ˜450 MeV . The moments are found to exhibit only mild pion-mass dependence when expressed in terms of appropriately chosen magneton units—the natural baryon magneton. A curious pattern is revealed among the anomalous baryon magnetic moments which is linked to the constituent quark model, however, careful scrutiny exposes additional features. Relations expected to hold in the large-Nc limit of QCD are studied; and, in one case, a clear preference for the quark model over the large-Nc prediction is found. The magnetically coupled Λ -Σ0 system is treated in detail at the S U (3 )F point, with the lattice QCD results comparing favorably with predictions based on S U (3 )F symmetry. This analysis enables the first extraction of the isovector transition magnetic polarizability. The possibility that large magnetic fields stabilize strange matter is explored, but such a scenario is found to be unlikely.
Carrier induced local moment magnetization in p-type Sn1-xMnxTe
NASA Astrophysics Data System (ADS)
Behera, Sashi S.; Tripathi, Pratibha; Nayak, Sanjeev K.; Tripathi, Gouri S.
2017-08-01
We derive a theory of carrier induced local moment magnetization of p-type Sn1-xMnxTe based on the Hubbard model, k → · π → electronic structure method (k → is the electronic wave vector and π → is the relativistic momentum operator) and the statistical paramagnetic approach for the localized moments. The Hubbard model is used to derive an internal exchange magnetic field. The difference in exchange self-energy is expressed in terms of an internal exchange field that is proportional to the parameter U, the onsite Coulomb repulsion, and the spin-density of carriers. In the present theory, the k → · π → + U model is integrated with the statistical paramagnetic theory for localized spins, which is then solved in a self-consistent manner by adding the exchange field to the applied field. The technique is applied to study the magnetic properties of p-type Sn1-xMnxTe, an important material for spintronics devices. The local moment magnetization calculated using the total magnetic field self-consistently agrees with the experimental observations. Magnetization and the exchange field studied as functions of the applied field, temperature and carrier concentration yield results on expected lines. Ours is a mechanism that is different from the RKKY interaction, normally invoked for carrier induced ferromagnetism and is thus a novelty.
Prediction and evaluation of magnetic moments in T =1 /2 , 3/2, and 5/2 mirror nuclei
NASA Astrophysics Data System (ADS)
Mertzimekis, Theo J.
2016-12-01
The Buck-Perez analysis of mirror nuclei magnetic moments has been applied on an updated set of data for T =1 /2 ,3 /2 mirror pairs and attempted for the first time for T =5 /2 nuclei. The spin expectation value for mirror nuclei up to mass A =63 has been reexamined. The main purpose is to test Buck-Perez analysis effectiveness as a prediction and—more importantly—an evaluation tool of magnetic moments in mirror nuclei. In this scheme, ambiguous signs of magnetic moments are resolved, evaluations of moments with multiple existing measurements have been performed, and a set of predicted values for missing moments, especially for several neutron-deficient nuclei is produced. A resolution for the case of the 57Cu ground-state magnetic moment is proposed. Overall, the method seems to be promising for future evaluations and planning future measurements.
Vingerhoets, P.; Avgoulea, M.; Bissell, M. L.; De Rydt, M.; Neyens, G.; Flanagan, K. T.; Billowes, J.; Cheal, B.; Mane, E.; Blaum, K.; Schug, M.; Brown, B. A.; Forest, D. H.; Tungate, G.; Geppert, Ch.; Noertershaeuser, W.; Honma, M.; Kowalska, M.; Kraemer, J.; Krieger, A.
2010-12-15
Measurements of the ground-state nuclear spins and magnetic and quadrupole moments of the copper isotopes from {sup 61}Cu up to {sup 75}Cu are reported. The experiments were performed at the CERN online isotope mass separator (ISOLDE) facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a {sup 56}Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is, however, strongly reduced at N=40 due to the parity change between the pf and g orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the {sup 56}Ni core and weakening of the Z=28 and N=28 shell gaps.
Electromagnetic Currents and Magnetic Moments in $\\chi$EFT
Saori Pastore, Luca Girlanda, Rocco Schiavilla, Michele Viviani, Robert Wiringa
2009-09-01
A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory ($\\chi$EFT) at, respectively, $Q^{\\, 2}$ (or N$^2$LO) and $e\\, Q$ (or N$^3$LO), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole ($M1$) operator associated with pion loops, consisting of two terms, one of which is determined, uniquely, by the isospin-dependent part of the two-pion-exchange potential. This decomposition is also carried out for the $M1$ operator arising from contact currents, in which the unique term is determined by the contact potential. Finally, the low-energy constants (LEC's) entering the N$^2$LO potential are fixed by fits to the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. Three additional LEC's are needed to completely specify the $M1$ operator at N$^3$L
NASA Astrophysics Data System (ADS)
Aguirre, R. M.; De Paoli, A. L.
2016-11-01
We obtain the covariant propagator at finite temperature for interacting baryons immersed in a strong magnetic field. The effect of the intrinsic magnetic moments on the Green function are fully taken into account. We make an expansion in terms of eigenfunctions of a Dirac field, which leads us to a compact form of its propagator. We present some simple applications of these propagators, where the statistical averages of nuclear currents and energy density are evaluated.
Magnetic moment jumps in flat and nanopatterned Nb thin-walled cylinders
NASA Astrophysics Data System (ADS)
Tsindlekht, M. I.; Genkin, V. M.; Felner, I.; Zeides, F.; Katz, N.; Gazi, Š.; Chromik, Š.; Dobrovolskiy, O. V.; Sachser, R.; Huth, M.
2017-02-01
Penetration of magnetic flux into hollow superconducting cylinders is investigated by magnetic moment measurements. The magnetization curves of a flat and a nanopatterned thin-walled superconducting Nb cylinders with a rectangular cross section are reported for the axial field geometry. In the nanopatterned sample, a row of micron-sized antidots (holes) was milled in the film along the cylinder axis. Magnetic moment jumps are observed for both samples at low temperatures for magnetic fields not only above Hc1, but also in fields lower than Hc1, i. e., in the vortex-free regime. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than Hc1. At temperatures above 0.66Tc and 0.78Tc the magnetization curves become smooth for the patterned and the as-prepared sample, respectively. The magnetization curve of a reference flat Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures.
Evidence of Charge Transfer and Orbital Magnetic Moment in Multiferroic CuFeO2
NASA Astrophysics Data System (ADS)
Narumi, Yasuo; Nakamura, Tetsuya; Ikeno, Hidekazu; Terada, Noriki; Morioka, Takayuki; Saito, Kota; Kitazawa, Hideaki; Kindo, Koichi; Nojiri, Hiroyuki
2016-11-01
Soft X-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of Fe and Cu L2,3 edges have been measured on the triangular lattice antiferromagnet CuFeO2. By applying sum rule analysis to the XMCD of Fe, the ratio of the orbital to spin magnetic moments is determined to be -0.071. Because the nominal valence of Fe in CuFeO2 was Fe3+ (3d5), the orbital magnetic moment was considered to be zero in the past. However, the present research demonstrates that the orbital magnetic moment of Fe takes a finite value and it is possibly due to Fe4+ (3d4), which is considered to be responsible for the strong magnetic anisotropy and the ferroelectricity. We compare the experimental results with the results of ab initio multiplet calculations based on the configuration interaction theory and discuss the anomalous electronic structures of Fe and Cu ions in CuFeO2.
Precessional damping of Fe magnetic moments in a FeNi film
NASA Astrophysics Data System (ADS)
Buschhorn, Stefan; Brüssing, Frank; Abrudan, Radu; Zabel, Hartmut
2011-04-01
We report on the element-resolved precessional dynamics of Fe magnetic moments in a homogeneous FeNi thin film. In our pump-probe experiment the magnetic system is excited by a magnetic field pulse from a stripline. The instantaneous response to the field-pulse excitation is monitored as a function of time in a stroboscopic measurement using element-selective x-ray resonant magnetic scattering (XRMS). Our data show that Fe and Ni moments are aligned parallel to each other at all times, while they oscillate around the effective field direction given by the step field pulse and applied bias field. The field dependence of the precessional motion and damping of Fe magnetic moments is analysed and compared with time-resolved magneto-optical Kerr effect (tr-MOKE) measurement data from the literature, showing good agreement. Additional studies prove the capability of our setup to conduct temperature-dependent studies. In the case of the presented FeNi system no changes in the frequency or damping behaviour are observed within a temperature range of 150-350 K.
Magnetic moments of octet baryons, angular momenta of quarks, and sea antiquark polarizations
Bartelski, Jan; Tatur, Stanislaw
2010-03-01
One can determine antiquark polarizations in a proton using the information from deep inelastic scattering, {beta} decays of baryons, orbital angular momenta of quarks, as well as their integrated magnetic distributions. The last quantities were determined previously by us performing a fit to magnetic moments of a baryon octet. However, because of the SU(3) symmetry our results depend on two parameters. The quantity {Gamma}{sub V}, measured recently in a COMPASS experiment, gives the relation between these parameters. We can fix the last unknown parameter using the ratio of up and down quark magnetic moments which one can get from the fit to radiative vector meson decays. We calculate antiquark polarizations with the orbital momenta of valence quarks that follow from lattice calculations. The value of the difference of up and down antiquark polarizations obtained in our calculations is consistent with the result obtained in a HERMES experiment.
31P NMR first spectral moment study of the partial magnetic orientation of phospholipid membranes.
Picard, F; Paquet, M J; Levesque, J; Bélanger, A; Auger, M
1999-01-01
Structural data can be obtained on proteins inserted in magnetically oriented phospholipid membranes such as bicelles, which are most often made of a mixture of long and short chain phosphatidylcholine. Possible shapes for these magnetically oriented membranes have been postulated in the literature, such as discoidal structures with a thickness of one bilayer and with the short acyl chain phosphatidylcholine on the edges. In the present paper, a geometrical study of these oriented structures is done to determine the validity of this model. The method used is based on the determination of the first spectral moment of solid-state (31)P nuclear magnetic resonance spectra. From this first moment, an order parameter is defined that allows a quantitative analysis of partially oriented spectra. The validity of this method is demonstrated in the present study for oriented samples made of DMPC, DMPC:DHPC, DMPC:DHPC:gramicidin A and adriamycin:cardiolipin. PMID:10423434
Field theory on R× S 3 topology. IV: Electrodynamics of magnetic moments
NASA Astrophysics Data System (ADS)
Carmeli, M.; Malin, S.
1986-08-01
The equations of electrodynamics for the interactions between magnetic moments are written on R×S3 topology rather than on Minkowskian space-time manifold of ordinary Maxwell's equations. The new field equations are an extension of the previously obtained Klein-Gordon-type, Schrödinger-type, Weyl-type, and Dirac-type equations. The concept of the magnetic moment in our case takes over that of the charge in ordinary electrodynamics as the fundamental entity. The new equations have R×S3 invariance as compared to the Lorentz invariance of Maxwell's equations. The solutions of the new field equations are given. In this theory the divergence of the electric field vanishes whereas that of the magnetic field does not.
Magnetic Moments of Delta and Omega- baryons with dynamical clover fermions
Aubin, Christopher; Orginos, Konstantinos; Pascalutsa, Vladimir; Vanderhaeghen, Marc
2009-01-01
We calculate the magnetic dipole moment of the Delta(1232) and Omega- baryons with 2+1-flavors of clover fermions on anisotropic lattices using a background magnetic field. This is the first dynamical calculation of these magnetic moments using a background field technique. The calculation for Omega- is done at the physical strange quark mass, with the result in units of the physical nuclear magneton Âµ_(Omega-) = -1.93(8)(12) (where the first error is statistical and the second is systematic) compared to the experimental number: -2.02(5). The Delta has been studied at three unphysical quark masses, corresponding to pion mass 366, 438, and 548 MeV. The pion-mass dependence is compared with the behavior obtained from chiral effective-field theory.
Decoherence-governed magnetic-moment dynamics of supported atomic objects
NASA Astrophysics Data System (ADS)
Gauyacq, Jean-Pierre; Lorente, Nicolás
2015-11-01
Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system’s size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the μK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching.
NASA Astrophysics Data System (ADS)
Inamori, Takaya; Sako, Nobutada; Nakasuka, Shinichi
2011-06-01
Nano-satellites provide space access to broader range of satellite developers and attract interests as an application of the space developments. These days several new nano-satellite missions are proposed with sophisticated objectives such as remote-sensing and observation of astronomical objects. In these advanced missions, some nano-satellites must meet strict attitude requirements for obtaining scientific data or images. For LEO nano-satellite, a magnetic attitude disturbance dominates over other environmental disturbances as a result of small moment of inertia, and this effect should be cancelled for a precise attitude control. This research focuses on how to cancel the magnetic disturbance in orbit. This paper presents a unique method to estimate and compensate the residual magnetic moment, which interacts with the geomagnetic field and causes the magnetic disturbance. An extended Kalman filter is used to estimate the magnetic disturbance. For more practical considerations of the magnetic disturbance compensation, this method has been examined in the PRISM (Pico-satellite for Remote-sensing and Innovative Space Missions). This method will be also used for a nano-astrometry satellite mission. This paper concludes that use of the magnetic disturbance estimation and compensation are useful for nano-satellites missions which require a high accurate attitude control.
Dissecting Reactor Antineutrino Flux Calculations.
Sonzogni, A A; McCutchan, E A; Hayes, A C
2017-09-15
Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from ^{235}U, ^{239}Pu, ^{241}Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In the present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the ^{238}U contribution as well as the effective charge and the allowed shape assumption used in the conversion method. We observe that including a shape correction of about +6% MeV^{-1} in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.
Dissecting Reactor Antineutrino Flux Calculations
NASA Astrophysics Data System (ADS)
Sonzogni, A. A.; McCutchan, E. A.; Hayes, A. C.
2017-09-01
Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from 235U, 239Pu, 241Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In the present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the 238U contribution as well as the effective charge and the allowed shape assumption used in the conversion method. We observe that including a shape correction of about +6 % MeV-1 in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.
Dissecting Reactor Antineutrino Flux Calculations
Sonzogni, A. A.; McCutchan, E. A.; Hayes, A. C.
2017-09-15
Current predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from 235 U , 239 Pu , 241 Pu and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In our present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the Huber-Mueller antineutrino spectra, including the 238 U contribution as wellmore » as the effective charge and the allowed shape assumption used in the conversion method. Here, we observe that including a shape correction of about + 6 % MeV - 1 in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.« less
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head
Tao, Y.; Eichler, A.; Holzherr, T.; Degen, C. L.
2016-01-01
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz−1/2, equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 106 T m−1 and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics. PMID:27647039
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head
NASA Astrophysics Data System (ADS)
Tao, Y.; Eichler, A.; Holzherr, T.; Degen, C. L.
2016-09-01
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz-1/2, equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 106 T m-1 and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ~10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics.
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head.
Tao, Y; Eichler, A; Holzherr, T; Degen, C L
2016-09-20
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz(-1/2), equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 10(6) T m(-1) and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics.
NASA Astrophysics Data System (ADS)
Kota, Yohei; Sakuma, Akimasa
2012-08-01
The magnetocrystalline anisotropy energy and orbital magnetic moment in L10-type transition metal alloys such as FePt, FePd, FeNi, CoPt, CoPd, and MnAl are evaluated while continuously varying the degree of order. The electronic structure with spin--orbit interaction is calculated by employing the tight-binding linear muffin-tin orbital method based on the local spin-density approximation. To control the degree of order, we consider a substitutional disorder and then adopt the coherent potential approximation. The magnetocrystalline anisotropy energy Δ E is roughly proportional to the power of the long-range order parameter S, i.e., Δ E \\propto Sn (n ˜ 1.6{--}2.4). We also discuss the relationship between the magnetocrystalline anisotropy energy and the orbital magnetic moment. In the same compositional system with different degrees of order, the difference between the orbital magnetic moment in the magnetic easy axis and that in the hard one is proportional to Δ E. However, the coefficient corresponding to the effective spin--orbit coupling is inconsistent with the intrinsic one in some cases.
Magnetic structure of Yb2Pt2Pb: Ising moments on the Shastry-Sutherland lattice
Miiller, W.; Zaliznyak, I.; Wu, L. S.; ...
2016-03-22
Neutron diffraction measurements were carried out on single crystals and powders of Yb2Pt2Pb, where Yb moments form two interpenetrating planar sublattices of orthogonal dimers, a geometry known as Shastry-Sutherland lattice, and are stacked along the c axis in a ladder geometry. Yb2Pt2Pb orders antiferromagnetically at TN=2.07K, and the magnetic structure determined from these measurements features the interleaving of two orthogonal sublattices into a 5×5×1 magnetic supercell that is based on stripes with moments perpendicular to the dimer bonds, which are along (110) and (–110). Magnetic fields applied along (110) or (–110) suppress the antiferromagnetic peaks from an individual sublattice, butmore » leave the orthogonal sublattice unaffected, evidence for the Ising character of the Yb moments in Yb2Pt2Pb that is supported by point charge calculations. Furthermore, specific heat, magnetic susceptibility, and electrical resistivity measurements concur with neutron elastic scattering results that the longitudinal critical fluctuations are gapped with ΔE≃0.07meV.« less
Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; ...
2017-06-23
We used lattice QCD calculations with background magnetic fields to determine the magnetic moments of the octet baryons. Computations are performed at the physical value of the strange quark mass, and two values of the light quark mass, one corresponding to the SU(3) flavor-symmetric point, where the pion mass is mπ ~ 800 MeV, and the other corresponding to a pion mass mπ ~ 450 MeV. The moments are found to exhibit only mild pion-mass dependence when expressed in terms of appropriately chosen magneton units---the natural baryon magneton. This suggests that simple extrapolations can be used to determine magnetic momentsmore » at the physical point, and extrapolated results are found to agree with experiment within uncertainties. A curious pattern is revealed among the anomalous baryon magnetic moments which is linked to the constituent quark model, however, careful scrutiny exposes additional features. Relations expected to hold in the large-Nc limit of QCD are studied; and, in one case, the quark model prediction is significantly closer to the extracted values than the large-Nc prediction. The magnetically coupled Λ-Σ0 system is treated in detail at the SU(3)F point, with the lattice QCD results comparing favorably with predictions based on SU(3)F symmetry. Our analysis enables the first extraction of the isovector transition magnetic polarizability. The possibility that large magnetic fields stabilize strange matter is explored, but such a scenario is found to be unlikely.« less
Large enhancement of magnetic moment in L10 ordered FePt thin films by Nd substitutional doping
NASA Astrophysics Data System (ADS)
Xu, D. B.; Sun, C. J.; Chen, J. S.; Heald, S. M.; Sanyal, B.; Rosenberg, R. A.; Zhou, T. J.; Chow, G. M.
2015-06-01
We studied L10 ordered Fe50Pt50-xNdx alloy films, which showed a large enhancement (~18.4% at room temperature and ~11.7% at 10 K) of magnetic moment with 6 atomic % of Nd. Analysis of the x-ray magnetic circular dichroism spectra at the Fe L3,2 edges and Nd M5,4 edges in Fe50Pt44Nd6 films indicated a significant contribution of the Nd orbital moment. The origin of the large enhancement of magnetic moment was attributed to the effect of ferromagnetic coupling of the total magnetic moments between Fe and Nd. Density functional theory based first principles calculations supported the experimental observations of increasing moment due to Nd substitution of Pt.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters.
Meyer, Jennifer; Tombers, Matthias; van Wüllen, Christoph; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-14
We present size dependent spin and orbital magnetic moments of cobalt (Con (+), 8 ≤ n ≤ 22), iron (Fen (+), 7 ≤ n ≤ 17), and nickel cluster (Nin (+), 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law "per cluster diameter," ∼n(-1/3), that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of "primary" and "secondary" (induced) orbital moments is invoked for interpretation.
Large enhancement of magnetic moment in L1(0) ordered FePt thin films by Nd substitutional doping
Xu, D. B.; Sun, C J; Chen, J. S.; Heald, S M; Sanyal, B.; Rosenberg, R. A.; Zhou, T. J.; Chow, G. M.
2015-07-01
We studied L1(0) ordered Fe50Pt50-xNdx alloy films, which showed a large enhancement (similar to 18.4% at room temperature and similar to 11.7% at 10 K) of magnetic moment with 6 atomic % of Nd. Analysis of the x-ray magnetic circular dichroism spectra at the Fe L-3,L-2 edges and Nd M-5,M-4 edges in Fe50Pt44Nd6 films indicated a significant contribution of the Nd orbital moment. The origin of the large enhancement of magnetic moment was attributed to the effect of ferromagnetic coupling of the total magnetic moments between Fe and Nd. Density functional theory based first principles calculations supported the experimental observations of increasing moment due to Nd substitution of Pt.
Research Update: Plentiful magnetic moments in oxygen deficient SrTiO{sub 3}
Lopez-Bezanilla, Alejandro; Ganesh, P.; Littlewood, Peter B.
2015-10-01
Correlated band theory is employed to investigate the magnetic and electronic properties of different arrangements of oxygen di- and tri-vacancy clusters in SrTiO{sub 3}. Hole and electron doping of oxygen deficient SrTiO{sub 3} yields various degrees of magnetization as a result of the interaction between localized magnetic moments at the defect sites. Different kinds of Ti atomic orbital hybridization are described as a function of the doping level and defect geometry. We find that magnetism in SrTiO{sub 3−δ} is sensitive to the arrangement of neighbouring vacancy sites, charge carrier density, and vacancy-vacancy interaction. Permanent magnetic moments in the absence of vacancy doping electrons are observed. Our description of the charged clusters of oxygen vacancies widens the previous descriptions of mono- and multi-vacancies and points out the importance of the controlled formation at the atomic level of defects for the realization of transition metal oxide based devices with a desirable magnetic performance.
Plentiful magnetic moments in oxygen deficient SrTiO3
Ganesh, Panchapakesan; Lopez-Bezanilla, Alejandro; Littlewood, Peter B.
2015-10-06
In this research, correlated band theory is employed to investigate the magnetic and electronic properties of different arrangements of oxygen di- and tri-vacancy clusters in SrTiO3. Hole and electron doping of oxygen deficient SrTiO3 yields various degrees of magnetization as a result of the interaction between localized magnetic moments at the defect sites. Different kinds of Ti atomic orbital hybridization are described as a function of the doping level and defect geometry. We find that magnetism in SrTiO3–δ is sensitive to the arrangement of neighbouring vacancy sites, charge carrier density, and vacancy-vacancy interaction. Permanent magnetic moments in the absence ofmore » vacancy doping electrons are observed. Our description of the charged clusters of oxygen vacancies widens the previous descriptions of mono- and multi-vacancies and points out the importance of the controlled formation at the atomic level of defects for the realization of transition metal oxide based devices with a desirable magnetic performance.« less
Plentiful magnetic moments in oxygen deficient SrTiO_{3}.
Lopez Bezanilla, Alejandro; Ganesh, P.; Littlewood, Peter B.
2015-10-01
Correlated band theory is employed to investigate the magnetic and electronic properties of different arrangements of oxygen di- and tri-vacancy clusters in SrTiO_{3}. Hole and electron doping of oxygen deficient SrTiO_{3} yields various degrees of magnetization as a result of the interaction between localized magnetic moments at the defected sites. Different kinds of Ti atomic orbital hybridization are described as a function of the doping level and defect geometry. We find that magnetism in SrTiO_{3}-d is sensitive to the arrangement of neighbouring vacancy sites, charge carrier density, and vacancy-vacancy interaction. Permanent magnetic moments in the absence of vacancy doping electrons are observed. Our description of the charged clusters of oxygen vacancies widens the previous descriptions of mono and multi-vacancies and points out the importance of the controlled formation at the atomic level of defects for the realization of transition metal oxide based devices with a desirable magnetic performance.
Moyotl, A.; Rosado, A.; Tavares-Velasco, G.
2011-10-01
The magnetic dipole moment and the electric dipole moment of leptons are calculated under the assumption of lepton flavor violation (LFV) induced by spin-1 unparticles with both vector and axial-vector couplings to leptons, including a CP-violating phase. The experimental limits on the muon magnetic dipole moment and LFV process, such as the decay l{sub i}{sup -}{yields}l{sub j}{sup -}l{sub k}{sup -}l{sub k}{sup +}, are then used to constrain the LFV couplings for particular values of the unparticle operator dimension d{sub U} and the unparticle scale {Lambda}{sub U}, assuming that LFV transitions between the tau and muon leptons are dominant. It is found that the current experimental constraints favor a scenario with dominance of the vector couplings over the axial-vector couplings. We also obtain estimates for the electric dipole moments of the electron and the muon, which are well below the experimental values.
The MOMENT Magnetic-Mapping Mission: A Nanosatellite for the Scientific Exploration of Mars
NASA Astrophysics Data System (ADS)
Eagleson, S.; Mauthe, S.; Sarda, K.; Spencer, H.; Zee, R. E.; Arkani-Hammed, J.
2008-08-01
MOMENT (Magnetic Observations of Mars Enabled by Nanosatellite Technology) is a nanosatellite that will obtain high-resolution maps of remnant magnetic fields present in the southern highlands of Mars. A European-developed magnetometer accurate to bet- ter than 0.5 nT and employed in a highly elliptical orbit with a relatively low, 100 km night-side, periapsis will provide much greater spatial resolution and delineation of local magnetic anomalies than is available from the initial surveys performed by Mars Global Surveyor (MGS). During the aerobraking phase of the MGS mission, low-altitude measurements were corrupted by solar wind because they were acquired under sunlit conditions where solar winds interacted with the crustal magnetic fields. During the mapping phase of the mission, spatial resolution was limited to about 400 km. Both of these issues will be overcome by MOMENT's low-altitude, night-side, observing strategy. The resulting magnetic-field maps, for the key areas of interest, will allow detailed studies of regional tectonics and the history of the planet's now- inactive core dynamo. MOMENT's design is based on the Space Flight Laboratory's Generic Nanosatellite Bus (GNB), which is also being developed for the BRITE space-astronomy and CanX-4&5 formation- flight missions. Nominally a 30 x 30 x 30 cm cube on the order of 10 kg mass, MOMENT uses as much GNB technology as possible to provide a rapid and cost-effective mission. The implementation of the mission requires payload space on a larger carrier spacecraft and the use of existing and future Martian communication relays for the transfer of information to and from Earth, necessitating a high level of international co-operation. MOMENT is otherwise fully independent and autonomous, even during scientific operations. This paper describes the conceptual (Canadian Space Agency funded) MOMENT mission and presents a strong case for the use of nanosatellite technology as a relatively simple and cost
Experimental determination of the magnetic dipole moment of candidate magnetoreceptor cells in trout
NASA Astrophysics Data System (ADS)
Winklhofer, M.; Eder, S.; Cadioiu, H.; McNaughton, P. A.; Kirschvink, J. L.
2011-12-01
Based on histological, physiological, and physical evidence, Walker et al (1997) and Diebel et al (2000) have identified distinctive cells in the olfactory epithelium of the rainbow trout (Onchorynchus mykiss) that contain magnetite and are closely associated with neurons that respond to changes in magnetic field. To put biophysical constraints on the possible transduction mechanism of magnetic signals, and in particular, to find out if the intracellular magnet is free to rotate or rather firmly anchored within the cell body, we have studied the magneto-mechanical response of isolated candidate receptor cells in suspension using a light microscope equipped with two pairs of Helmholtz coils. From the characteristic re-orientation time of suspended cells after a change in magnetic field direction, we have determined the magnitude of the magnetic dipole moment of the cells in function of the external field strength (0.4 mT to 3.2 mT) in order to find out whether or not the natural magnetic moment is remanence-based or induced (i.e., single-domain vs. superparamagnetic/multi-domain). Results: 1) The mechanical response of isolated cells to a change in magnetic field direction was always immediate, irrespective of the direction of change, which implies that the intracellular magnet is not free to rotate in the cell, but rather rigidly attached, probably to the plasma membrane, which is also suggested by our confocal fluorescence-microscope studies. 2) The cellular dipole moment turned out to be independent of the external field strength. Thus, the natural magnetic dipole moment is based on magnetic remanence, which points to single-domain particles and corroborates the results by Diebel et al (2000), who obtained switching fields consistent with single-domain magnetite. 3). The magnetic dipole moment is found to be of the order of several tens of fAm2, which greatly exceeds previous estimates (0.5 fAm2), and thus is similar to values reported for the most strongly
NASA Astrophysics Data System (ADS)
Zhou, X.; Ma, L.; Shi, Z.; Fan, W. J.; Evans, R. F. L.; Zheng, Jian-Guo; Chantrell, R. W.; Mangin, S.; Zhang, H. W.; Zhou, S. M.
2015-03-01
In this work, disordered-IrMn3/insulating-Y3Fe5O12 exchange-biased bilayers are studied. The behavior of the net magnetic moment ΔmAFM in the antiferromagnet is directly probed by anomalous and planar Hall effects, and anisotropic magnetoresistance. The ΔmAFM is proved to come from the interfacial uncompensated magnetic moment. We demonstrate that the exchange bias and rotational hysteresis loss are induced by partial rotation and irreversible switching of the ΔmAFM. In the athermal training effect, the state of the ΔmAFM cannot be recovered after one cycle of hysteresis loop. This work highlights the fundamental role of the ΔmAFM in the exchange bias and facilitates the manipulation of antiferromagnetic spintronic devices.
Masses and magnetic moments of heavy flavour baryons in the hyper central model
NASA Astrophysics Data System (ADS)
Patel, Bhavin; Rai, Ajay Kumar; Vinodkumar, P. C.
2008-06-01
Heavy flavour baryons containing one or two charm (beauty) quarks with light flavour combinations are studied using the hyper central description of the three-body system. The confinement potential is assumed as hyper central Coulomb plus power potential with a power index p. The ground state (J^P=\\frac{1}{2}^+ and \\frac{3}{2}^+ ) masses of heavy flavour baryons are computed for different power indices, p starting from 0.5 to 2.0. The predicted masses are found to attain a saturated value with respect to the variation in p beyond the power index p > 1.0. Using the spin-flavour structure of the constituting quarks and by defining the effective mass of the confined quarks within the baryons, the magnetic moments are computed with no additional free parameters. The masses and magnetic moments of the single heavy and double heavy flavour baryons are found to be in accordance with other model predictions.
New bounds on neutrino electric millicharge from GEMMA experiment on neutrino magnetic moment
NASA Astrophysics Data System (ADS)
Brudanin, Victor B.; Medvedev, Dmitry V.; Starostin, Alexander S.; Studenikin, Alexander I.
2016-04-01
Using the new limit on the neutrino anomalous magnetic moment recently obtained by GEMMA experiment we get an order-of-magnitude estimation for possible new direct upper bound on the neutrino electric millicharge |qν | ˜ 1.5 ×10-12e0 (e0 is the absolute value of the electron charge) by comparing the neutrino magnetic moment and millicharge contributions to the total cross section at the electron recoil energy threshold of the experiment. This estimation is confirmed by the performed analysis of the GEMMA data using established statistical procedures and a new direct bound on the neutrino millicharge absolute value |qν | < 2.7 ×10-12e0 (90%CL) is derived. This limit is more stringent than the previous one obtained from the TEXONO reactor experiment data that is included to the Review of Particle Properties 2012.
Feng, Xu; Jansen, Karl; Petschlies, Marcus; Renner, Dru B
2011-08-19
We present a reliable nonperturbative calculation of the QCD correction, at leading order in the electromagnetic coupling, to the anomalous magnetic moment of the electron, muon, and tau leptons using two-flavor lattice QCD. We use multiple lattice spacings, multiple volumes, and a broad range of quark masses to control the continuum, infinite-volume, and chiral limits. We examine the impact of the commonly ignored disconnected diagrams and introduce a modification to the previously used method that results in a well-controlled lattice calculation. We obtain 1.513(43)×10(-12), 5.72(16)×10(-8), and 2.650(54)×10(-6) for the leading-order two-flavor QCD correction to the anomalous magnetic moment of the electron, muon, and tau, respectively, each accurate to better than 3%.
Neutrino scattering on atomic electrons in searches for the neutrino magnetic moment.
Voloshin, M B
2010-11-12
The scattering of a neutrino on atomic electrons is considered in the situation where the energy transferred to the electrons is comparable to the characteristic atomic energies, as relevant to the current experimental search for the neutrino magnetic moment. The process is induced by the standard electroweak interaction as well as by the possible neutrino magnetic moment. Quantum-mechanical sum rules are derived for the inclusive cross section at a fixed energy deposited in the atomic system, and it is shown that the differential over the energy transfer cross section is given, modulo very small corrections, by the same expression as for free electrons, once all possible final states of the electronic system are taken into account. Thus, the atomic effects effectively cancel in the inclusive process.
Zhou, X.; Ma, L.; Shi, Z.; Fan, W. J.; Evans, R. F. L.; Zheng, Jian-Guo; Chantrell, R. W.; Mangin, S.; Zhang, H. W.; Zhou, S. M.
2015-01-01
In this work, disordered-IrMn3/insulating-Y3Fe5O12 exchange-biased bilayers are studied. The behavior of the net magnetic moment ΔmAFM in the antiferromagnet is directly probed by anomalous and planar Hall effects, and anisotropic magnetoresistance. The ΔmAFM is proved to come from the interfacial uncompensated magnetic moment. We demonstrate that the exchange bias and rotational hysteresis loss are induced by partial rotation and irreversible switching of the ΔmAFM. In the athermal training effect, the state of the ΔmAFM cannot be recovered after one cycle of hysteresis loop. This work highlights the fundamental role of the ΔmAFM in the exchange bias and facilitates the manipulation of antiferromagnetic spintronic devices. PMID:25777540
The measurement of the anomalous magnetic moment of the muon at Fermilab
Logashenko, I.
2015-06-17
The anomalous magnetic moment of the muon is one of the most precisely measured quantities in experimental particle physics. Its latest measurement at Brookhaven National Laboratory deviates from the Standard Model expectation by approximately 3.5 standard deviations. The goal of the new experiment, E989, now under construction at Fermilab, is a fourfold improvement in precision. Furthermore, we discuss the details of the future measurement and its current status.
Magnetic moments of spherical nuclei: Status of the problem and unsolved issues
Borzov, I. N.; Saperstein, E. E. Tolokonnikov, S. V.
2008-03-15
Dipole magnetic moments of more than 100 odd spherical nuclei are calculated within the theory of finite Fermi systems. For the effective interaction of nucleons within the theory of finite Fermi systems, use is made of a version that takes into account nuclear-medium-modified amplitudes for the exchange of one pion and one rho meson. A new tensor local charge {zeta}{sub t} is incorporated in the theory of finite Fermi systems in addition to the known orbital ({zeta}{sub l}) and spin ({zeta}{sub s}) local charges. Good agreement with experimental data, at a level of 0.1 to 0.2{mu}{sub N}, is obtained for the overwhelming majority of the nuclei considered here. Several cases of a significant discrepancy with experimental data, at a level of 0.3 to 0.5{mu}{sub N}, are revealed. Possibilities for removing these discrepancies are discussed. A detailed comparison with known results obtained within the multiparticle shell model is performed for 2p-to 1f-shell nuclei. Cases where the standard theory of finite Fermi systems must be extended by taking into account multiparticle configurations are found. Magnetic moments are analyzed for a number of long isotopic chains. Several new experimental values of magnetic moments for copper isotopes far from the beta-stability valleys are known. For the example of the copper-isotope chain, it is shown how the emergence of a deformation in the ground state of a nucleus can be revealed on the basis of a systematic analysis of magnetic moments.
The Measurement of the Anomalous Magnetic Moment of the Muon at Fermilab a)
NASA Astrophysics Data System (ADS)
Logashenko, I.; Grange, J.; Winter, P.; Carey, R. M.; Hazen, E.; Kinnaird, N.; Miller, J. P.; Mott, J.; Roberts, B. L.; Crnkovic, J.; Morse, W. M.; Sayed, H. Kamal; Tishchenko, V.; Druzhinin, V. P.; Shatunov, Y. M.; Bjorkquist, R.; Chapelain, A.; Eggert, N.; Frankenthal, A.; Gibbons, L.; Kim, S.; Mikhailichenko, A.; Orlov, Y.; Rider, N.; Rubin, D.; Sweigart, D.; Allspach, D.; Barzi, E.; Casey, B.; Convery, M. E.; Drendel, B.; Freidsam, H.; Johnstone, C.; Johnstone, J.; Kiburg, B.; Kourbanis, I.; Lyon, A. L.; Merritt, K. W.; Morgan, J. P.; Nguyen, H.; Ostiguy, J.-F.; Para, A.; Polly, C. C.; Popovic, M.; Ramberg, E.; Rominsky, M.; Soha, A. K.; Still, D.; Walton, T.; Yoshikawa, C.; Jungmann, K.; Onderwater, C. J. G.; Debevec, P.; Leo, S.; Pitts, K.; Schlesier, C.; Anastasi, A.; Babusci, D.; Corradi, G.; Hampai, D.; Palladino, A.; Venanzoni, G.; Dabagov, S.; Ferrari, C.; Fioretti, A.; Gabbanini, C.; Di Stefano, R.; Marignetti, S.; Iacovacci, M.; Mastroianni, S.; Di Sciascio, G.; Moricciani, D.; Cantatore, G.; Karuza, M.; Giovanetti, K.; Baranov, V.; Duginov, V.; Khomutov, N.; Krylov, V.; Kuchinskiy, N.; Volnykh, V.; Gaisser, M.; Haciomeroglu, S.; Kim, Y.; Lee, S.; Lee, M.; Semertzidis, Y. K.; Won, E.; Fatemi, R.; Gohn, W.; Gorringe, T.; Bowcock, T.; Carroll, J.; King, B.; Maxfield, S.; Smith, A.; Teubner, T.; Whitley, M.; Wormald, M.; Wolski, A.; Al-Kilani, S.; Chislett, R.; Lancaster, M.; Motuk, E.; Stuttard, T.; Warren, M.; Flay, D.; Kawall, D.; Meadows, Z.; Syphers, M.; Tarazona, D.; Chupp, T.; Tewlsey-Booth, A.; Quinn, B.; Eads, M.; Epps, A.; Luo, G.; McEvoy, M.; Pohlman, N.; Shenk, M.; de Gouvea, A.; Welty-Rieger, L.; Schellman, H.; Abi, B.; Azfar, F.; Henry, S.; Gray, F.; Fu, C.; Ji, X.; Li, L.; Yang, H.; Stockinger, D.; Cauz, D.; Pauletta, G.; Santi, L.; Baessler, S.; Frlez, E.; Pocanic, D.; Alonzi, L. P.; Fertl, M.; Fienberg, A.; Froemming, N.; Garcia, A.; Hertzog, D. W.; Kammel, P.; Kaspar, J.; Osofsky, R.; Smith, M.; Swanson, E.; Lynch, K.
2015-09-01
The anomalous magnetic moment of the muon is one of the most precisely measured quantities in experimental particle physics. Its latest measurement at Brookhaven National Laboratory deviates from the Standard Model expectation by approximately 3.5 standard deviations. The goal of the new experiment, E989, now under construction at Fermilab, is a fourfold improvement in precision. Here, we discuss the details of the future measurement and its current status.
Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment
Fonseca, I. C.; Bakke, K.
2016-01-07
Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.
Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment.
Fonseca, I C; Bakke, K
2016-01-07
Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.
The decay μ-->eγ and the anomalous W-boson magnetic moment
NASA Astrophysics Data System (ADS)
Queijeiro, A.; Rivera, J. M.
1991-09-01
We compute the branching ratio of μ-->eγ decay, allowing for an anomalous magnetic dipole moment κ of the W boson. We find that an enhancement up to 3 orders of magnitude can be achieved for the interval -3<=κ<=3. In models with heavy neutral leptons, such as the ``fine-tuning of parameters'' scenario depicted by Cheng and Li, this leads to a large 10-11-1012 branching ratio.
Spin and orbital moments of Co-carbide nanoparticles for permanent magnet applications
NASA Astrophysics Data System (ADS)
Arena, D. A.; Sterbinsky, G. E.; Carroll, K. J.; Yoon, H.; Meng, S.; Huba, Z. J.; Carpenter, E. E.
2014-03-01
Many efforts are currently devoted to the development of rare earth free permanent magnets (REFPMs). In newly developed permanent magnet materials, examination of the atomic scale magnetic properties is critical to gaining knowledge of the mechanisms of magnetism and hence furthering the development of these materials. X-ray magnetic circular dichroism (XMCD) is a core-level technique ideally suited for such studies as it provides element-specific information on magnetic properties. We present an XMCD study of the REFPM nanoparticulate Co-carbide using a new high-field end-station at beamline U4B of the National Synchrotron Light Source. This end-station facilitates measurement of XMCD spectra from magnetically hard materials. The Co-Carbide nanoparticles (NPs) under study are synthesized via wet chemical methods, which can lead to differences between the atomic and magnetic structures of the surface and bulk of NPs. To separate the determination of the surface and bulk magnetic properties we have combined our XMCD measurements with in-situ surface treatment. Preliminary measurements of Co L-edge XMCD spectra and element specific hysteresis point to the role of the Co orbital and spin moments in the establishment of the high coercive field and (BH)max in Co-carbide NPs.
Analyzing power in pion-proton bremsstrahlung, and the. Delta. sup ++ (1232) magnetic moment
Bosshard, A.; Amsler, C.; Doebeli, M.; Doser, M.; Schaad, M.; Riedlberger, J.; Truoel, P. ); Bistirlich, J.A.; Crowe, K.M.; Ljungfelt, S.; Meyer, C.A. ); van den Brandt, B.; Konter, J.A.; Mango, S.; Renker, D. ); Loude, J.F.; Perroud, J.P. ); Haddock, R.P. ); Sober, D.I. )
1991-10-01
We report on a first measurement of the polarized-target asymmetry of the pion-proton bremsstrahlung cross section ({pi}{sup +}{ital p}{r arrow}{pi}{sup {minus}}{ital p}{gamma}). As in previous cross section measurements the pion energy (298 MeV) and the detector geometry for this experiment was chosen to optimize the sensitivity to the radiation from the magnetic dipole moment of the {Delta}{sup ++}(1232) resonance {mu}{sub {Delta}}. Comparison to a recent isobar model for pion-nucleon bremsstrahlung yields {mu}{sub {Delta}}=(1.62{plus minus}0.18){mu}{sub {ital p}}, where {mu}{sub {ital p}} is the proton magnetic moment. Since the asymmetry depends less than the cross section on the choice of the other input parameters for the model, their uncertainties affect this analysis by less than the experimental error. However the theory fails to represent both the cross section and the asymmetry data at the highest photon energies. Hence further improvements in the calculations are needed before the model dependence of the magnetic moment analysis can be fully assessed. The present result agrees with bag-model corrections to the SU(6) prediction {mu}{sub {Delta}}=2{mu}{sub {ital p}}. As a by-product, the analyzing power for elastic {pi}{sup +}{ital p} scattering at 415 MeV/{ital c} was also measured. This second result is in good agreement with phase shift calculations.
LaCoO3 (LCO) - Dramatic changes in Magnetic Moment in fields to 500T
NASA Astrophysics Data System (ADS)
Lee, Y.; Harmon, B. N.
LCO has attracted great attention over the years (>2000 publications) because of its unusual magnetic properties; although in its ground state at low temperatures it is non-magnetic. A recent experiment[1] in pulsed fields to 500T showed a moment of ~1.3μB above 140T, and above ~270T the magnetization rises, reaching ~3.8μB by 500T. We have performed first principles DFT calculations for LCO in high fields. Our earlier calculations[2] explained the importance of a small rhombohedral distortion in the ground state that leads to a suppression of the 1.3μB moment for fields below ~140T. By allowing fairly large atomic displacements in high fields, moments of ~4μB are predicted. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division under Contract No. DE-AC02-07CH11358.
Strange Quark Magnetic Moment of the Nucleon at the Physical Point.
Sufian, Raza Sabbir; Yang, Yi-Bo; Alexandru, Andrei; Draper, Terrence; Liang, Jian; Liu, Keh-Fei
2017-01-27
We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051 GeV^{2}≲Q^{2}≲1.31 GeV^{2}. The finite lattice spacing and finite volume corrections are included in a global fit with 24 valence quark masses on four lattices with different lattice spacings, different volumes, and four sea quark masses including one at the physical pion mass. We obtain the strange magnetic moment G_{M}^{s}(0)=-0.064(14)(09)μ_{N}. The four-sigma precision in statistics is achieved partly due to low-mode averaging of the quark loop and low-mode substitution to improve the statistics of the nucleon propagator. We also obtain the strange charge radius ⟨r_{s}^{2}⟩_{E}=-0.0043(16)(14) fm^{2}.
Gd-doped BaSnO3: A transparent conducting oxide with localized magnetic moments
NASA Astrophysics Data System (ADS)
Alaan, Urusa S.; Shafer, Padraic; N'Diaye, Alpha T.; Arenholz, Elke; Suzuki, Y.
2016-01-01
We have synthesized transparent, conducting, paramagnetic stannate thin films via rare-earth doping of BaSnO3. Gd3+ (4f7) substitution on the Ba2+ site results in optical transparency in the visible regime, low resistivities, and high electron mobilities, along with a significant magnetic moment. Pulsed laser deposition was used to stabilize epitaxial Ba0.96Gd0.04SnO3 thin films on (001) SrTiO3 substrates, and compared with Ba0.96La0.04SnO3 and undoped BaSnO3 thin films. Gd as well as La doping schemes result in electron mobilities at room temperature that exceed those of conventional complex oxides, with values as high as 60 cm2/V.s (n = 2.5 × 1020 cm-3) and 30 cm2/V.s (n = 1 × 1020 cm-3) for La and Gd doping, respectively. The resistivity shows little temperature dependence across a broad temperature range, indicating that in both types of films the transport is not dominated by phonon scattering. Gd-doped BaSnO3 films have a strong magnetic moment of ˜7 μB/Gd ion. Such an optically transparent conductor with localized magnetic moments may unlock opportunities for multifunctional devices in the design of next-generation displays and photovoltaics.
The qqqqq components and hidden flavor contributions to the baryon magnetic moments
An, C. S.; Li, Q. B.; Riska, D. O.; Zou, B. S.
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 the 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.
Strange Quark Magnetic Moment of the Nucleon at the Physical Point
NASA Astrophysics Data System (ADS)
Sufian, Raza Sabbir; Yang, Yi-Bo; Alexandru, Andrei; Draper, Terrence; Liang, Jian; Liu, Keh-Fei; χ QCD Collaboration
2017-01-01
We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051 GeV2≲Q2≲1.31 GeV2 . The finite lattice spacing and finite volume corrections are included in a global fit with 24 valence quark masses on four lattices with different lattice spacings, different volumes, and four sea quark masses including one at the physical pion mass. We obtain the strange magnetic moment GMs(0 )=-0.064 (14 )(09 )μN. The four-sigma precision in statistics is achieved partly due to low-mode averaging of the quark loop and low-mode substitution to improve the statistics of the nucleon propagator. We also obtain the strange charge radius ⟨rs2⟩E=-0.0043 (16 )(14 ) fm2 .
Leptophilic dark matter and the anomalous magnetic moment of the muon
Agrawal, Prateek; Chacko, Zackaria; Verhaaren, Christopher B.
2014-08-26
We consider renormalizable theories such that the scattering of dark matter off leptons arises at tree level, but scattering off nuclei only arises at loop. In this framework, the various dark matter candidates can be classified by their spins and by the forms of their interactions with leptons. In this study, we determine the corrections to the anomalous magnetic moment of the muon that arise from its interactions with dark matter. We then consider the implications of these results for a set of simplified models of leptophilic dark matter. When a dark matter candidate reduces the existing tension between themore » standard model prediction of the anomalous magnetic moment and the experimental measurement, the region of parameter space favored to completely remove the discrepancy is highlighted. Conversely, when agreement is worsened, we place limits on the parameters of the corresponding simplified model. These bounds and favored regions are compared against the experimental constraints on the simplified model from direct detection and from collider searches. Although these constraints are severe, we find there do exist limited regions of parameter space in these simple theories that can explain the observed anomaly in the muon magnetic moment while remaining consistent with all experimental bounds.« less
Leptophilic dark matter and the anomalous magnetic moment of the muon
Agrawal, Prateek; Chacko, Zackaria; Verhaaren, Christopher B.
2014-08-26
We consider renormalizable theories such that the scattering of dark matter off leptons arises at tree level, but scattering off nuclei only arises at loop. In this framework, the various dark matter candidates can be classified by their spins and by the forms of their interactions with leptons. In this study, we determine the corrections to the anomalous magnetic moment of the muon that arise from its interactions with dark matter. We then consider the implications of these results for a set of simplified models of leptophilic dark matter. When a dark matter candidate reduces the existing tension between the standard model prediction of the anomalous magnetic moment and the experimental measurement, the region of parameter space favored to completely remove the discrepancy is highlighted. Conversely, when agreement is worsened, we place limits on the parameters of the corresponding simplified model. These bounds and favored regions are compared against the experimental constraints on the simplified model from direct detection and from collider searches. Although these constraints are severe, we find there do exist limited regions of parameter space in these simple theories that can explain the observed anomaly in the muon magnetic moment while remaining consistent with all experimental bounds.
Liu, Haiyi; Sun, Jianfei; Wang, Haoyao; Wang, Peng; Song, Lina; Li, Yang; Chen, Bo; Zhang, Yu; Gu, Ning
2015-06-08
A kinetics-based method is proposed to quantitatively characterize the collective magnetization of colloidal magnetic nanoparticles. The method is based on the relationship between the magnetic force on a colloidal droplet and the movement of the droplet under a gradient magnetic field. Through computational analysis of the kinetic parameters, such as displacement, velocity, and acceleration, the magnetization of colloidal magnetic nanoparticles can be calculated. In our experiments, the values measured by using our method exhibited a better linear correlation with magnetothermal heating, than those obtained by using a vibrating sample magnetometer and magnetic balance. This finding indicates that this method may be more suitable to evaluate the collective magnetism of colloidal magnetic nanoparticles under low magnetic fields than the commonly used methods. Accurate evaluation of the magnetic properties of colloidal nanoparticles is of great importance for the standardization of magnetic nanomaterials and for their practical application in biomedicine.
APPLICATION OF MAGNETIC TORQUING FOR DESATURATION OF CONTROL MOMENT GYROS IN SPACE VEHICLE CONTROL.
space vehicle by exchanging momentum with the rest of the spacecraft. However, externally caused disturbance torques acting on the vehicle would saturate the momentum capability of the gyros if no auxiliary torquing methods were provided to unload the stored momentum. This function can be performed by a set of three current-carrying coils which interact with the earth’s magnetic field in a process of continually resetting the control moment gyro gimbal angles to ’zero’ position. The performance and weight of a magnetic system to momentum desaturate control
Bandgap and magnetic moment of Ga1-xCrxN
NASA Astrophysics Data System (ADS)
Bhatia, Manjeet; Srivastava, Anurag
2017-05-01
We report a DFT based ab-initio analysis of ground state properties, electronic structure and magnetic properties Cr (25%, 50% and 75%) doped GaN compound in its zincblende phase. It is observed that bulk modulus is found to decrease with increasing Cr concentration. The semiconducting GaN transforms to metallic due to introduction of Chromium at the site of Ga in GaN. The computed electronic density shows a half-metallic behavior of doped compound with a magnetic moment of 3 µB/ Cr-atom.
Nuclear Magnetic Moment of {sup 210}Fr: A Combined Theoretical and Experimental Approach
Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; Iskrenova-Tchoukova, E.; Safronova, M. S.
2008-05-02
We measure the hyperfine splitting of the 9S{sub 1/2} level of {sup 210}Fr, and find a magnetic dipole hyperfine constant A=622.25(36) MHz. The theoretical value, obtained using the relativistic all-order method from the electronic wave function at the nucleus, allows us to extract a nuclear magnetic moment of 4.38(5){mu}{sub N} for this isotope, which represents a factor of 2 improvement in precision over previous measurements. The same method can be applied to other rare isotopes and elements.
Analogue of the quantum Hall effect for neutral particles with magnetic dipole moment
NASA Astrophysics Data System (ADS)
Ribeiro, L. R.; Passos, E.; Furtado, C.; Sergeenkov, S.
2017-03-01
In this paper we investigate a possibility for the existence of an analog of the Quantum Hall Effect for neutral particles with a permanent magnetic moment μ in the presence of crossed inhomogeneous magnetic and electric fields. We predict the appearance of Hall conductivity σH = (e2 / h) ν (μ) with the Landau filling factor ν (μ) ∝μ2. The estimates of the model parameters suggest quite an optimistic possibility to experimentally verify this prediction in optically trapped clouds of atomic BEC.
NASA Astrophysics Data System (ADS)
Granroth, G. E.; Aczel, A. A.; Fernandez-Baca, J. A.; Nagler, S. E.
2013-03-01
Many experimental features in magnetic superconductors are also present when these complex materials are in the normal state. Therefore studies of simpler itinerant magnets may help provide understanding of these phenomena. We chose to study Gd as it is has an ~ 0 . 6μB itinerant moment in addition to a ~ 7 . 0μB localized moment. The SEQUOIA spectrometer, at the Spallation Neutron Source at Oak Ridge National Laboratory, was used in fine resolution mode with Ei=50 meV neutrons, to measure the magnetic excitations in a 12 gm 160Gd single crystal. The crystal was mounted with the h 0 l plane horizontal and rotated around the vertical axis to map out the excitations. The measured magnetic structure factor for the acoustic modes in the hh 0 direction has an intensity step at h ~ 0 . 3 . Electronic band structure calculations (W. M. Temmerman and P. A. Sterne, J. Phys: Condes. Matter,2, 5529 (1990)) show this Q position to be near several band crossings of the Fermi surface. A detailed analysis, including instrumental resolution, is presented to clarify any relationship between the magnetic structure factor and the electronic band structure. This work was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.
Magnetic moment of inertia within the torque-torque correlation model.
Thonig, Danny; Eriksson, Olle; Pereiro, Manuel
2017-04-19
An essential property of magnetic devices is the relaxation rate in magnetic switching which strongly depends on the energy dissipation. This is described by the Landau-Lifshitz-Gilbert equation and the well known damping parameter, which has been shown to be reproduced from quantum mechanical calculations. Recently the importance of inertia phenomena have been discussed for magnetisation dynamics. This magnetic counterpart to the well-known inertia of Newtonian mechanics, represents a research field that so far has received only limited attention. We present and elaborate here on a theoretical model for calculating the magnetic moment of inertia based on the torque-torque correlation model. Particularly, the method has been applied to bulk itinerant magnets and we show that numerical values are comparable with recent experimental measurements. The theoretical analysis shows that even though the moment of inertia and damping are produced by the spin-orbit coupling, and the expression for them have common features, they are caused by very different electronic structure mechanisms. We propose ways to utilise this in order to tune the inertia experimentally, and to find materials with significant inertia dynamics.
Rollins, Nancy K.; Liang, Hui; Park, Yong Jong
2015-01-01
Purpose: Most orthodontic appliances are made of stainless steel materials and induce severe magnetic susceptibility artifacts in brain MRI. In an effort for correcting these artifacts, it is important to know the value of induced magnetic moments in all parts of orthodontic appliances. In this study, the induced magnetic moment of stainless steel orthodontic brackets, molar bands, and arch-wires from several vendors is measured. Methods: Individual stainless steel brackets, molar bands, and short segments of arch-wire were positioned in the center of spherical flask filled with water through a thin plastic rod. The induced magnetic moment at 1.5 T was determined by fitting the B0 map to the z-component of the magnetic dipole field using a computer routine. Results: The induced magnetic moment at 1.5 T was dominated by the longitudinal component mz, with a small contribution from the transverse components. The mz was insensitive to the orientation of the metal parts. The orthodontic brackets collectively dominated the magnetic dipole moment in orthodontic appliances. In brackets from six vendors, the total induced mz from 20 brackets for nonmolar teeth ranged from 0.108 to 0.158 (median 0.122) A ⋅ m2. The mz in eight molar bands with bracket attachment from two vendors ranged from 0.0004 to 0.0166 (median 0.0035) A ⋅ m2. Several full length arch wires had induced magnetic moment in the range of 0.006–0.025 (median 0.015) A ⋅ m2. Conclusions: Orthodontic brackets collectively contributed most to the total magnetic moment. Different types of brackets, molar bands, and arch wires all exhibit substantial variability in the induced magnetic moment. PMID:26429261
NASA Astrophysics Data System (ADS)
Kitano, M.; Bourzutschky, M.; Calaprice, F. P.; Clayhold, J.; Happer, W.; Musolf, M.
1986-11-01
The magnetic moments of xenon atoms (129Xem and 131Xem) have been measured with a high precision nuclear-magnetic-resonance method. The nuclei of gaseous xenon were polarized by spin exchange with optically pumped rubidium and the polarization was measured by gamma-ray anisotropy. The static magnetic field for the nuclear magnetic resonance experiment was stabilized and calibrated by optical pumping magnetometers. The measured magnetic moments are ||μ(129m)||=0.891 223(4) μN and ||μ(131>)||=0.994 048(6) μN.
Magnetic field non-uniformity challenges in neutron electric dipole moment experiments
NASA Astrophysics Data System (ADS)
Nouri, Nima
A new neutron Electric Dipole Moment (nEDM) experiment will be performed at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source (SNS) of the Oak Ridge National Laboratory (ORNL). The underlying theme of this experiment (first conceived by Golub and Lamoreaux in 1994 [1]) is the search for new physics beyond the Standard Model of particle physics. The experiment has the potential to reveal new sources of time reversal (T) and charge conservation and parity (CP) violation. The discovery of a non-zero nEDM would be of revolutionary importance to physics. This provides evidence for new-beyond-the-Standard-Model physics, which required for a resolution to the unresolved puzzle of why the universe is dominated by matter, as opposed to anti-matter. The basic principle upon which experimental searches for a neutron EDM employing stored ultracold neutrons (UCN) are based concerns measurements of the neutrons' Larmor spin precession frequencies nu+/- in parallel (+) and anti-parallel (-) magnetic ([special character omitted]) and electric ([special character omitted]) fields. A value for, or a limit on, the neutron EDM is then deduced from a comparison of the measured values of nu+ and nu-. However, the experiment bound is limited by different systematic effects such as magnetic-field. A central problem to all neutron EDM experiments concerns the challenge of real-time determination of the magnetic field vector components present within some interior region of the experimental apparatus (UCN container) over which it is impossible to directly measure the field components during the operation of the experiment. This is essential for the optimization of several experimental parameters directly related to the statistical sensitivity, and for monitoring various systematic errors. A first demonstration of a new magnetic field monitoring system for a neutron electric dipole moment experiment is presented. The system is designed to reconstruct the vector
Ratio of Isoscalar to Isovector Core Polarization Contributions to Magnetic Moments
NASA Astrophysics Data System (ADS)
Robinson, Shadow; Zamick, Larry; Sharon, Yitzhak
2010-11-01
We found that large scale calculations of isoscalar magnetic moments of odd-odd N=Z nuclei yielded results remarkably similar to those of simple single j calculations. To understand why we use a delta interaction times (1+xPs) where Ps is the spin exchange operator, to calculate the ratio IS/IV of the core polarization contributions to the magnetic moments. The spin exchange contributes a factor (1-2x) to this ratio. A popular choice is x=1/3 for which (1-2x) is also 1/3. Another contribution comes from the fact that the coupling of j=l+1/2 to j'=l-1/2 via the magnetic moment operator is proportional to (gs-gl). The IS values are gl=0.5 gs=0.88; the IV values are 0.5 and 4.71. This yields a (gs-gl) ratio of 0.09 which together with the 1/3 from spin exchange tells us that the isoscalar core polarization is a mere 3% of isovector. If we further divide by single j values to get effective charge corrections then the ration IS/IV ends up being 0.06 (or 6%). We thus gain understanding of the resuts in ref [1] of the near equality of large scale and single j results for IS moments.[4pt] [1] S.Yeager, S.J.Q. Robinson, L.Zamick and Y.Y.Sharon, EPL 88, 52001 (2009)
Ye, Mao; Kuroda, Kenta; Takeda, Yukiharu; Saitoh, Yuji; Okamoto, Kazuaki; Zhu, Si-Yuan; Shirai, Kaito; Miyamoto, Koji; Arita, Masashi; Nakatake, Masashi; Okuda, Taichi; Ueda, Yoshifumi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Kimura, Akio
2013-06-12
We have found a perpendicular magnetic anisotropy of iron adatoms on a surface of the prototypical three-dimensional topological insulator Bi2Se3 by using x-ray magnetic circular dichroism measurements. The orbital magnetic moment of Fe is strongly enhanced at lower coverage, where angle-resolved photoemission spectroscopy shows coexistence of non-trivial topological states at the surface.
Magnetic and Distribution of Magnetic Moments in Amorphous Fe89.7 P10.3 Alloy Nanowire Arrays
NASA Astrophysics Data System (ADS)
Shi, Hui-Gang; Xue, De-Sheng
2008-01-01
Binary amorphous Fe89.7P10.3 alloy nanowire arrays in diameter of about 40nm and length of about 3 μm have been fabricated in an anodic aluminium oxide template by electrodeposition. Magnetic properties of the samples are investigated by mean of vibrating sample magnetometer, transmission Mössbauer spectroscopy and conversion electron Mössbauer spectroscopy at room temperature. It is found that the nanowire arrays have obvious perpendicular magnetic anisotropy and are ferromagnetic at room temperature, with its Mössbauer spectra consisting of six broad lines. The average angles between the Fe magnetic moment and the wire axis are about 14° inside and 28° at the end of the amorphous Fe89.7P10.3 alloy nanowire arrays, respectively. The magnetic behaviour is decided by the shape anisotropy and the dipolar interaction between wires. In addition, the magnetic moments distribution is theoretically demonstrated by using the symmetric fanning mechanism of the spheres chain model.
Evidence of half-metallic interface magnetism via local moment formation in Co based Heusler alloys
Telling, N. D.; Keatley, P.S.; van der Laan, G.; Hicken, R.J.; Arenholz, E.; Sakuraba, Y.; Oogane, M.; Ando, Y.; Miyazaki, T.
2008-08-18
In this work we use a combination of x-ray magnetic circular and linear dichroism (XMCD and XMLD) techniques to examine the formation of local moments in Heusler alloys of the composition Co{sub 2}MnX (where X=Si or Al). The existence of local moments in a half-metallic system is reliant upon the band gap in the minority-spin states. By utilizing the element-specific nature of x-ray techniques we are able to explore the origin of the minority-spin band gap in the partial density of states (PDOS), via the degree of localization of moments on Co and Mn atoms. We observe a crucial difference in the localization of the Co moment when comparing Co{sub 2}MnSi (CMS) and Co{sub 2}MnAl (CMA) films that is consistent with the predicted larger minority-spin gap in the Co PDOS for CMS. These results provide important evidence for the dominant role of the Co minority-spin states in realizing half-metallic ferromagnetism (HMF) in these Heusler alloys. They also demonstrate a direct method for measuring the degree of interfacial HMF in the raw materials without the need for fabricating spin-transport devices.
Remote sensing of the magnetic moment of uranus: predictions for voyager.
Hill, T W; Dessler, A J
1985-03-22
Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system.
Reactor antineutrinos and nuclear physics
NASA Astrophysics Data System (ADS)
Balantekin, A. B.
2016-11-01
Short-baseline reactor neutrino experiments successfully measured the neutrino parameters they set out to measure, but they also identified a shape distortion in the 5-7 MeV range as well as a reduction from the predicted value of the flux. Nuclear physics input into the calculations of reactor antineutrino spectra needs to be better refined if this anomaly is to be interpreted as due to sterile neutrino states.
Song, Zhigang; Quhe, Ruge; Liu, Shunquan; Li, Yan; Feng, Ji; Yang, Yingchang; Lu, Jing; Yang, Jinbo
2015-09-11
In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. Compared to circular pumping, elliptical pumping is a more universal and effective method to create coherent valley polarization. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping.
Song, Zhigang; Quhe, Ruge; Liu, Shunquan; Li, Yan; Feng, Ji; Yang, Yingchang; Lu, Jing; Yang, Jinbo
2015-01-01
In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. Compared to circular pumping, elliptical pumping is a more universal and effective method to create coherent valley polarization. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping. PMID:26358835
Magnetic moment of the XQ state with JP C=1+± in light cone QCD sum rules
NASA Astrophysics Data System (ADS)
Agamaliev, A. K.; Aliev, T. M.; Savcı, M.
2017-02-01
The magnetic moments of the recently observed resonance Xb(5568 ) by D0 Collaboration and its partner with charm quark are calculated in the framework of the light cone QCD sum rules, by assuming that these resonances are represented as tetraquark states with quantum numbers JP C=1+±. The magnetic moment can play a critical role in the determination of the quantum numbers, as well as give useful information about the inner structure of these mesons.
Magnetic field component demonstration for a neutron electric dipole moment search
NASA Astrophysics Data System (ADS)
Slutsky, Simon
2016-09-01
A neutron electric dipole moment (EDM) search at the Oak Ridge National Laboratory's Spallation Neutron Source (SNS) will probe with a sensitivity of < 5 ×10-28 e-cm. Trapped, polarized ultracold neutrons will precess in a constant magnetic field and variable electric field, and a non-zero neutron EDM will appear as a variation in the precession frequency correlated with the electric field. Magnetic field gradients must be kept below 10 pT/cm to mitigate false EDMs produced by the geometric phase effect and to maximize the neutron spin-relaxation lifetime. I will discuss a prototype magnetic shielding system, including a nearly-hermetic superconducting lead shield, built to demonstrate the required gradients at 1/3-scale of the final experiment. Additionally, the system will evaluate the eddy current heating due to RF fields produced by a proposed neutron-``spin-dressing'' technique.
Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors
Tam, Yu -T.; Ku, W.; Yao, D. -X.
2015-09-10
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well nested Fermi surfaces is found to induce significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling, rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor coupling reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order.
Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors
Tam, Yu -T.; Ku, W.; Yao, D. -X.
2015-09-10
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well nested Fermi surfaces is found to induce significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling, rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor couplingmore » reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order.« less
Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch.
Baker, S H; Roy, M; Thornton, S C; Binns, C
2012-05-02
We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu(1-x)Au(x) matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ~2.5 ± 0.3 μ(B)/atom .
Atomic moments in Mn2CoAl thin films analyzed by X-ray magnetic circular dichroism
Jamer, M. E.; Assaf, B. A.; Sterbinsky, G. E.; ...
2014-12-05
Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn2CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. Results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value.
NASA Astrophysics Data System (ADS)
Alling, B.; Körmann, F.; Grabowski, B.; Glensk, A.; Abrikosov, I. A.; Neugebauer, J.
2016-06-01
We study the impact of lattice vibrations on magnetic and electronic properties of paramagnetic bcc and fcc iron at finite temperature, employing the disordered local moments molecular dynamics (DLM-MD) method. Vibrations strongly affect the distribution of local magnetic moments at finite temperature, which in turn correlates with the local atomic volumes. Without the explicit consideration of atomic vibrations, the mean local magnetic moment and mean field derived magnetic entropy of paramagnetic bcc Fe are larger compared to paramagnetic fcc Fe, which would indicate that the magnetic contribution stabilizes the bcc phase at high temperatures. In the present study we show that this assumption is not valid when the coupling between vibrations and magnetism is taken into account. At the γ -δ transition temperature (1662 K), the lattice distortions cause very similar magnetic moments of both bcc and fcc structures and hence magnetic entropy contributions. This finding can be traced back to the electronic densities of states, which also become increasingly similar between bcc and fcc Fe with increasing temperature. Given the sensitive interplay of the different physical excitation mechanisms, our results illustrate the need for an explicit consideration of vibrational disorder and its impact on electronic and magnetic properties to understand paramagnetic Fe. Furthermore, they suggest that at the γ -δ transition temperature electronic and magnetic contributions to the Gibbs free energy are extremely similar in bcc and fcc Fe.
Magnetic Tunnel Junctions Incorporating a Near-Zero-Moment Ferromagnetic Semiconductor
NASA Astrophysics Data System (ADS)
Warring, H.; Trodahl, H. J.; Plank, N. O. V.; Natali, F.; Granville, S.; Ruck, B. J.
2016-10-01
We present a fully semiconductor-based magnetic tunnel junction that uses spin-orbit coupled materials made of intrinsic ferromagnetic semiconductors. Unlike more common approaches, one of the electrodes consists of a near-zero magnetic-moment ferromagnetic semiconductor, samarium nitride, with the other electrode composed of the more conventional ferromagnetic semiconductor gadolinium nitride. Fabricated tunnel junctions show a magnetoresistance as high as 200%, implying strong spin polarization in both electrodes. In contrast to conventional tunnel junctions, the resistance is largest at high fields, a direct result of the orbital-dominant magnetization in samarium nitride that requires that the spin in this electrode must align opposite to that in the gadolinium nitride when the magnetization is saturated. The magnetoresistance at intermediate fields is controlled by the formation of a twisted magnetization phase in the samarium nitride, a direct result of the orbital-dominant ferromagnetism. Thus, an alternative type of functionality can be brought to magnetic tunnel junctions by the use of different electrode materials, in contrast to the usual focus on tuning the barrier properties.
Determination of Local Magnetic Dipole Moment of the Plasma at the PUPR Cusp-Mirror Machine
Leal-Quiros, Edbertho; Prelas, Mark
2006-12-04
A novel diagnostic that allows measurement of the magnetic moment {mu} has been designed. The {mu}-Analyzer consists of a Directional Energy Analyzer and a Magnetic Hall Probe in the same detector miniature case. The Directional Energy Analyzer measures the ion temperature in the perpendicular direction to the magnetic field. On the other side, the Hall Probe measures the magnetic field. The {mu}-Analyzer is a miniature analyzer to avoid plasma perturbation. This allows the measurement of the ion temperature and the local magnetic field at the same point at the same time, therefore {mu}, the first adiabatic invariant is found. From the above parameters, the local Larmor radius also will be calculated. From the analysis of the data simultaneously in time and space, the {mu} of the Local Plasma has been determined. This result is a very important quantity, among other properties that permit one to know the stability of the magnetic confinement device using the MHD Stability Criterium, and also very important in Space Plasma Research. In addition to the above, a direct measurement of the Larmor radius of each position is also possible. The experiments have been made in a Cusp/Mirror Plasma Machine where plasma parameters such as Density and Temperature are relatively easy to change in a very wide range.
Multiferroicity and spiral magnetism in FeVO{sub 4} with quenched Fe orbital moments
Daoud-Aladine, A.; Chapon, L. C.; Kundys, B.; Martin, C.; Simon, C.; Radaelli, P. G.; Brown, P. J.
2009-12-01
FeVO{sub 4} has been studied by heat capacity, magnetic susceptibility, electric polarization and single-crystal neutron-diffraction experiments. The triclinic crystal structure is made of S-shaped clusters of six Fe{sup 3+} ions, linked by VO{sub 4}{sup 3-} groups. Two long-range magnetic ordering transitions occur at T{sub N1}=22 K and T{sub N2}=15 K. Both magnetic structures are incommensurate and below T{sub N2}, FeVO{sub 4} becomes weakly ferroelectric coincidentally with the loss of the collinearity of the magnetic structure in a very similar fashion than in the classical TbMnO{sub 3} multiferroic material. However we argue that the symmetry considerations and the mechanisms invoked to explain these properties in TbMnO{sub 3} do not straightforwardly apply to FeVO{sub 4}. First, the magnetic structures, even the collinear structure, are all acentric so that ferroelectricity in FeVO{sub 4} is not correlated with the fact magnetic ordering is breaking inversion symmetry. Regarding the mechanism, FeVO{sub 4} has quenched orbital moments that questions the exact role of the spin-orbit interactions.
NASA Astrophysics Data System (ADS)
Deák, A.; Simon, E.; Balogh, L.; Szunyogh, L.; dos Santos Dias, M.; Staunton, J. B.
2014-06-01
We develop a self-consistent relativistic disordered local moment (RDLM) scheme aimed at describing finite-temperature magnetism of itinerant metals from first principles. Our implementation in terms of the Korringa-Kohn-Rostoker multiple-scattering theory and the coherent potential approximation allows us to relate the orientational distribution of the spins to the electronic structure, thus a self-consistent treatment of the distribution is possible. We present applications for bulk bcc Fe, L10-FePt, and FeRh ordered in the CsCl structure. The calculations for Fe show significant variation of the local moments with temperature, whereas according to the mean-field treatment of the spin fluctuations the Curie temperature is overestimated. The magnetic anisotropy of FePt alloys is found to depend strongly on intermixing between nominally Fe and Pt layers, and it shows a power-law behavior as a function of magnetization for a broad range of chemical disorder. In the case of FeRh we construct a lattice constant vs temperature phase diagram and determine the phase line of metamagnetic transitions based on self-consistent RDLM free-energy curves.
(83)Kr nuclear magnetic moment in terms of that of (3)He.
Makulski, Włodzimierz
2014-08-01
High resolution NMR spectroscopy was applied to precisely determine the (83)Kr nuclear magnetic dipole moment on the basis of new results available for nuclear magnetic shielding in krypton and helium-3 atoms. Small amounts of (3)He as the solutes and (83)Kr as the buffer gas were observed in (3)He and (83)Kr NMR spectra at the constant external field, B0 = 11.7578 T. In each case, the resonance frequencies (ν(He) and ν(Kr)) were linearly dependent on the density of gaseous solvent. The extrapolation of experimental points to the zero density of gaseous krypton allowed for the evaluation of both resonance frequencies free from intermolecular interactions. By combining these measurements with the recommended (83)Kr chemical shielding value, the nuclear magnetic moment could be determined with much better precision than ever before, μ((83)Kr) = -0.9707297(32)μN, with the improvement due to the greater accuracy of the spectral data. Copyright © 2014 John Wiley & Sons, Ltd.
Kong, Dali; Lin, Wei; Pan, Yongxin; Zhang, Keke
2014-01-01
We investigate the swimming motion of rod-shaped magnetotactic bacteria affiliated with the Nitrospirae phylum in a viscous liquid under the influence of an externally imposed, time-dependent magnetic field. By assuming that fluid motion driven by the translation and rotation of a swimming bacterium is of the Stokes type and that inertial effects of the motion are negligible, we derive a new system of the twelve coupled equations that govern both the motion and orientation of a swimming rod-shaped magnetotactic bacterium with a growing magnetic moment in the laboratory frame of reference. It is revealed that the initial pattern of swimming motion can be strongly affected by the rate of the growing magnetic moment. It is also revealed, through comparing mathematical solutions of the twelve coupled equations to the swimming motion observed in our laboratory experiments with rod-shaped magnetotactic bacteria, that the laboratory trajectories of the swimming motion can be approximately reproduced using an appropriate set of the parameters in our theoretical model. PMID:24523716
NASA Astrophysics Data System (ADS)
Gabrielse, Gerald
2011-05-01
The electron magnetic moment in Bohr magnetons has been measured to a precision of 3 parts in 1013. This measurement, with quantum electrodynamics (AED) theory, provides the most precise value of the fine structure constant. This measurement, with a value of the fine structure from other measurements, also tests QED and sets a limit on the internal structure of the electron. A one-electron quantum cyclotron is at the heart of the measurement -- an electron suspended in a magnetic field and cooled enough that its lowest cyclotron and spin quantum states can be deduced with quantum nondemolition (QND) measurements. A cylindrical Penning trap cavity inhibits spontaneous emission and feedback methods make the electron excite and sustain its own motion for detection. A new apparatus is being commissioned in pursuit of more precise measurements. Adapted methods are promising for observing a proton spin flip, which should make it possible to compare the antiproton and proton magnetic moments a million times more accurately than is currently possible.
NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.
Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye B; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał
2016-06-28
An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine μ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find μ((207)Pb) = 0.59064 μN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of μ((207)Pb), in the range of 0.59000-0.59131 μN.
NASA Astrophysics Data System (ADS)
Cnossen, Ingrid; Richmond, Arthur D.; Wiltberger, Michael
2012-05-01
The strength of the Earth's magnetic field changes over time. We use simulations with the Coupled Magnetosphere-Ionosphere-Thermosphere model to investigate how the magnetosphere, upper atmosphere, and solar quiet (Sq) geomagnetic variation respond as the geomagnetic dipole moment M varies between 2ṡ1022 and 10ṡ1022 Am2. We find that the magnetopause stand-off distance and the cross-polar cap potential increase, while the polar cap size decreases, with increasing M. Their dependence on M is stronger than predicted by previous studies. We also show for the first time that the shape of the magnetosphere starts to change for M ≤ 4ṡ1022 Am2. This may be due to enhanced magnetopause erosion and/or to strong changes in the ionospheric conductance, which affect the field-aligned currents and the magnetic fields they create in the magnetosphere, thus modifying the magnetic pressure inside the magnetosphere. E × B drift velocities, Joule heating power, the global mean thermospheric temperature and the global mean height of the peak of the ionospheric F2 layer, hmF2, all increase with increasing M for low dipole moments, but all decrease with increasing M for larger dipole moments. The peak electron density of the F2 layer, NmF2, shows the opposite behavior. The Sq amplitude decreases with increasing M and this dependence can be roughly described by a power law scaling. Most scaling relations show a weak dependence on the solar activity level, which is likely associated with a change in the relative contributions to the Pedersen conductance from the upper and lower ionosphere, which scale differently with M.
Experimental evidence of pressure-induced suppression of the cobalt magnetic moment in ErCo{sub 2}
Ishimatsu, N.; Miyamoto, S.; Maruyama, H.; Chaboy, J.; Laguna-Marco, M. A.; Kawamura, N.
2007-05-01
X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements have demonstrated the modification of the magnetic moment of Co in ErCo{sub 2} induced by applying pressure. Co K-edge and Er L{sub 2}-edge XAS and XMCD spectra recorded under applied hydrostatic pressures up to 4.2 GPa reveal that the modification of the magnetic properties of Co proceeds through two different pressure regimes. At low pressure, the Co atoms show an ordered magnetic moment induced by the effective field created by the Er sublattice. The Co moment progressively diminishes as the applied pressure increases, but it is not canceled for applied pressures of up to 4.2 GPa. The results show that the pressure mainly affects the Co subsystem without affecting the magnetism of the Er sublattice.
NASA Technical Reports Server (NTRS)
Srnka, L. J.
1976-01-01
The acquisition of thermoremanent magnetization (TRM) by a cooling spherical shell is studied for internal magnetizing dipole fields, using Runcorn's (1975) theorems on magnetostatics. If the shell cools progressively inward, inner regions acquire TRM in a net field composed of the dipole source term plus a uniform field due to the outer magnetized layers. In this case, the global dipole moment and external remanent field are nonzero when the whole shell has cooled below the Curie point and the source dipole has disappeared. The remanent field outside the shell is found to depend on the thickness, radii, and cooling rate of the shell, as well as the coefficient of TRM and the intensity of the magnetizing field. Some implications for the moon's remanent dipole moment are discussed.
Topological protection of electronic states against disorder probed by their magnetic moment
NASA Astrophysics Data System (ADS)
Tadjine, Athmane; Delerue, Christophe
2017-06-01
Magnetic moments (MMs) of electrons in topological insulator quantum dots (TI-QDs) are investigated using a model system, namely a multiorbital honeycomb lattice. Their nature and orientation with respect to the spin are studied. We show that large MMs are not specific to edge states in nontrivial gaps, as band states can host even larger MMs. However, we demonstrate that edge-state and band-state MMs have a totally different sensitivity to disorder. Measuring the MMs in TI-QDs is therefore a direct way to probe the nontrivial to trivial topological transition under increasing disorder.
Magnetic moment of the majorana neutrino in the left-right symmetric model
Boyarkin, O. M. Boyarkina, G. G.
2013-04-15
Corrections to the neutrino magnetic dipole moment from the singly charged Higgs bosons h{sup ({+-})} and {delta}-tilde{sup (}{+-}) were calculated within the left-right symmetric model involving Majorana neutrinos. It is shown that, if the h{sup ({+-})} and {delta}-tilde{sup (}{+-}) bosons lie at the electroweak scale, the contributions from Higgs sector are commensurate with the contribution of charged gauge bosons or may even exceed it. The behavior of the neutrino flux inmatter and in amagnetic field was studied. It was found that resonance transitions between light and heavy neutrinos are forbidden.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-07
The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Lattice calculation of hadronic light-by-light contribution to the muon anomalous magnetic moment
Blum, Thomas; Christ, Norman; Hayakawa, Masashi; ...
2016-01-12
The quark-connected part of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment is computed using lattice QCD with chiral fermions. Here we report several significant algorithmic improvements and demonstrate their effectiveness through specific calculations which show a reduction in statistical errors by more than an order of magnitude. The most realistic of these calculations is performed with a near-physical 171 MeV pion mass on a (4.6 fm)3 spatial volume using the 323×64 Iwasaki+DSDR gauge ensemble of the RBC/UKQCD Collaboration.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; ...
2015-01-07
The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Beda, A.G.; Demidova, E.V.; Gavrilov, M.G.; Kornoukhov, V.N.; Starostin, A.S.; Brudanin, V.B.; Egorov, V.G.; Vylov, C.
2004-11-01
The investigation of the background structure of the spectrometer GEMMA was carried out in a low-background laboratory in ITEP. GEMMA is destined for measurement of the neutrino magnetic moment near the core of a nuclear power plant (NPP) reactor. The results of the investigation in ITEP and measurement of the background in the experimental hall at the Kalininskaya NPP proved that GEMMA is ready for the start of the experiment at the reactor. Now the preparation of the experimental hall for the measurement is completed and an assembling of the setup is in progress.
Hyperfine field of einsteinium in iron and nuclear magnetic moment of {sup 254}Es
Severijns, N.; Kraev, I. S.; Phalet, T.; Tandecki, M.; Traykov, E.; Gorp, S. Van; Wauters, F.; Belyaev, A. A.; Lukhanin, A. A.; Noga, V. I.; Erzinkyan, A. L.; Parfenova, V. P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V. T.; Toporov, Yu. G.; Zotov, E.; Golovko, V. V.; Gurevich, G. M.
2009-06-15
The angular distributions of {gamma} rays and {alpha} particles from oriented {sup 250}Bk, {sup 253,254}Es, and {sup 255}Fm nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |B{sub hf}(EsFe{sub lowbar|})=396(32) T. With this value the magnetic moment of {sup 254}Es was then determined as |{mu}|=4.35(41) {mu}{sub N}.
Z = 50 core stability in 110Sn from magnetic-moment and lifetime measurements
Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K. -H.; ...
2016-04-18
In this study, the structure of the semimagic Sn50 isotopes were previously studied via measurements of B(E2;21+ → 01+) and g factors of 21+ states. The values of the B(E2;21+) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. This work presents the first measurement of the 21+ and 41+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B(E2) values.
Measurement of the magnetic moment of the 10{sup +} isomer in {sup 132}Ba
Harissopulos, S.; Gelberg, A.; Dewald, A.; Hass, M.; Weissman, L.; Broude, C.
1995-10-01
The magnetic moment of the 10{sup +} isomeric state of {sup 132}Ba at 3115 keV was measured as {ital g}={minus}0.156(11). A 60 MeV {sup 12}C beam from the Koffler Pelletron accelerator at the Weizmann Institute was used in the reaction {sup 124}Sn({sup 12}C,4{ital n}){sup 132}Ba. The measured {ital g} factor confirms the ({nu}{ital h}{sub 11/2}){sup {minus}2} configuration of the level. The result is compared with other {ital g} factors in neighboring {ital N}=76 isotones.
Using baryon octet magnetic moments and masses to fix the pion cloud contribution
Franz L. Gross; Ramalho, Gilberto T. F.; Tsushima, Kazuo
2010-05-12
In this study, using SU(3) symmetry to constrain themore » $$\\pi BB'$$ couplings, assuming SU(3) breaking comes only from one-loop pion cloud contributions, and using the the covariant spectator theory to describe the photon coupling to the quark core, we show how the experimental masses and magnetic moments of the baryon octet can be used to set a model independent constraint on the strength of the pion cloud contributions to the octet, and hence the nucleon, form factors at $Q^2=0$.« less
A 17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle
NASA Astrophysics Data System (ADS)
Akhmedov, E. Kh.; Senjanovic, G.; Tao, Zhijian; Berezhiani, Z. G.
1992-08-01
Zee-type models with Majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, a particularly simple solution is found to the solar neutrino problem, which besides nu(sub 17) predicts a light Zeldovich-Konopinski-Mahmoud neutrino nu(sub light) = nu(sub e) + nu(sub mu)(sup c) with a magnetic moment being easily as large as 10(exp -11)(mu)(sub B) through the Barr-Freire-Zee mechanism.
17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle
NASA Astrophysics Data System (ADS)
Akhmedov, Eugeni Kh.; Berezhiani, Zurab G.; Senjanović, Goran; Tao, Zhijian
1993-01-01
Zee-type models with majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, we find a particularly simple solution to the solar neutrino problem, which besides ν17 predicts a light Zeldovich-Konopinski-Mahmoud neutrino νlight = νe + νcμ with a magnetic moment being easily as large as 10 -11μB through the Barr-Freire-Zee mechanism.
Photon equation of motion with application to the electron's anomalous magnetic moment
Ritchie, A B
2007-12-06
The photon equation of motion previously applied to the Lamb shift is here applied to the anomalous magnetic moment of the electron. Exact agreement is obtained with the QED result of Schwinger. The photon theory treats the radiative correction to the photon in the presence of the electron rather than its inverse as in standard QED. The result is found to be first-order in the photon-electron interaction rather than second-order as in standard QED, introducing an ease of calculation hitherto unavailable.
Electron Anomalous Magnetic Moment in Basis Light-Front Quantization Approach
Zhao, Xingbo; Honkanen, Heli; Maris, Pieter; Vary, James P.; Brodsky, Stanley J.; /SLAC
2012-02-17
We apply the Basis Light-Front Quantization (BLFQ) approach to the Hamiltonian field theory of Quantum Electrodynamics (QED) in free space. We solve for the mass eigenstates corresponding to an electron interacting with a single photon in light-front gauge. Based on the resulting non-perturbative ground state light-front amplitude we evaluate the electron anomalous magnetic moment. The numerical results from extrapolating to the infinite basis limit reproduce the perturbative Schwinger result with relative deviation less than 1.2%. We report significant improvements over previous works including the development of analytic methods for evaluating the vertex matrix elements of QED.
Blum, T; Boyle, P A; Izubuchi, T; Jin, L; Jüttner, A; Lehner, C; Maltman, K; Marinkovic, M; Portelli, A; Spraggs, M
2016-06-10
We report the first lattice QCD calculation of the hadronic vacuum polarization (HVP) disconnected contribution to the muon anomalous magnetic moment at physical pion mass. The calculation uses a refined noise-reduction technique that enables the control of statistical uncertainties at the desired level with modest computational effort. Measurements were performed on the 48^{3}×96 physical-pion-mass lattice generated by the RBC and UKQCD Collaborations. We find the leading-order hadronic vacuum polarization a_{μ}^{HVP(LO)disc}=-9.6(3.3)(2.3)×10^{-10}, where the first error is statistical and the second systematic.
Using baryon octet magnetic moments and masses to fix the pion cloud contribution
Franz L. Gross; Ramalho, Gilberto T. F.; Tsushima, Kazuo
2010-05-12
In this study, using SU(3) symmetry to constrain the $\\pi BB'$ couplings, assuming SU(3) breaking comes only from one-loop pion cloud contributions, and using the the covariant spectator theory to describe the photon coupling to the quark core, we show how the experimental masses and magnetic moments of the baryon octet can be used to set a model independent constraint on the strength of the pion cloud contributions to the octet, and hence the nucleon, form factors at $Q^2=0$.
Unquenched quark model for baryons: Magnetic moments, spins, and orbital angular momenta
Bijker, R.; Santopinto, E.
2009-12-15
We present an unquenched quark model for baryons in which the effects of the quark-antiquark pairs (uu, dd, and ss) are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechanism. In the present approach, the contribution of the quark-antiquark pairs can be studied for any inital baryon and for any flavor of the qq pairs. It is shown that, while the inclusion of the qq pairs does not affect the baryon magnetic moments, it leads to a sizable contribution of the orbital angular momentum to the spin of the proton and the {lambda} hyperon.
Remote sensing of the magnetic moment of Uranus - Predictions for Voyager
NASA Astrophysics Data System (ADS)
Hill, T. W.; Dessler, A. J.
1985-03-01
The current understanding of the power transfer mechanisms by which power is supplied to a planet's magnetosphere by the kinetic energy of planetary spin and the energy flux of the impinging solar wind is applied to the case of Uranus, in order to predict the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and UV spectrometer (UVS) instruments of the Voyager spacecraft. The power available for the two energy transfer phenomena cited is a function of Uranus' magnetic moment, which is presently derived for each power source as a function of the date of first detection of radio emissions by the PRA or auroral emissions by the UVS.
Lattice calculation of hadronic light-by-light contribution to the muon anomalous magnetic moment
Blum, Thomas; Christ, Norman; Hayakawa, Masashi; Izubuchi, Taku; Jin, Luchang; Lehner, Christoph
2016-01-12
The quark-connected part of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment is computed using lattice QCD with chiral fermions. Here we report several significant algorithmic improvements and demonstrate their effectiveness through specific calculations which show a reduction in statistical errors by more than an order of magnitude. The most realistic of these calculations is performed with a near-physical 171 MeV pion mass on a (4.6 fm)^{3} spatial volume using the 32^{3}×64 Iwasaki+DSDR gauge ensemble of the RBC/UKQCD Collaboration.
NASA Astrophysics Data System (ADS)
Meinert, Markus; Schmalhorst, Jan-Michael; Klewe, Christoph; Reiss, Günter; Arenholz, Elke; Böhnert, Tim; Nielsch, Kornelius
2011-10-01
Epitaxial thin films of the half-metallic Xa compound Mn2CoGa (Hg2CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality films with a bulk magnetization of 1.95(5)μB per unit cell were obtained. The L3,2 x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory (DFT) and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism, in good agreement with theory as well, allows us to distinguish between itinerant and local Mn moments. Based on noncollinear spin DFT, it is shown that one of the two Mn moments has local character, whereas the other Mn moment and the Co moment are itinerant.
AGM2015: Antineutrino Global Map 2015
Usman, S.M.; Jocher, G.R.; Dye, S.T.; McDonough, W.F.; Learned, J.G.
2015-01-01
Every second greater than 1025 antineutrinos radiate to space from Earth, shining like a faint antineutrino star. Underground antineutrino detectors have revealed the rapidly decaying fission products inside nuclear reactors, verified the long-lived radioactivity inside our planet, and informed sensitive experiments for probing fundamental physics. Mapping the anisotropic antineutrino flux and energy spectrum advance geoscience by defining the amount and distribution of radioactive power within Earth while critically evaluating competing compositional models of the planet. We present the Antineutrino Global Map 2015 (AGM2015), an experimentally informed model of Earth’s surface antineutrino flux over the 0 to 11 MeV energy spectrum, along with an assessment of systematic errors. The open source AGM2015 provides fundamental predictions for experiments, assists in strategic detector placement to determine neutrino mass hierarchy, and aids in identifying undeclared nuclear reactors. We use cosmochemically and seismologically informed models of the radiogenic lithosphere/mantle combined with the estimated antineutrino flux, as measured by KamLAND and Borexino, to determine the Earth’s total antineutrino luminosity at . We find a dominant flux of geo-neutrinos, predict sub-equal crust and mantle contributions, with ~1% of the total flux from man-made nuclear reactors. PMID:26323507
AGM2015: Antineutrino Global Map 2015.
Usman, S M; Jocher, G R; Dye, S T; McDonough, W F; Learned, J G
2015-09-01
Every second greater than 10(25) antineutrinos radiate to space from Earth, shining like a faint antineutrino star. Underground antineutrino detectors have revealed the rapidly decaying fission products inside nuclear reactors, verified the long-lived radioactivity inside our planet, and informed sensitive experiments for probing fundamental physics. Mapping the anisotropic antineutrino flux and energy spectrum advance geoscience by defining the amount and distribution of radioactive power within Earth while critically evaluating competing compositional models of the planet. We present the Antineutrino Global Map 2015 (AGM2015), an experimentally informed model of Earth's surface antineutrino flux over the 0 to 11 MeV energy spectrum, along with an assessment of systematic errors. The open source AGM2015 provides fundamental predictions for experiments, assists in strategic detector placement to determine neutrino mass hierarchy, and aids in identifying undeclared nuclear reactors. We use cosmochemically and seismologically informed models of the radiogenic lithosphere/mantle combined with the estimated antineutrino flux, as measured by KamLAND and Borexino, to determine the Earth's total antineutrino luminosity at . We find a dominant flux of geo-neutrinos, predict sub-equal crust and mantle contributions, with ~1% of the total flux from man-made nuclear reactors.
Sterile antineutrino search in the MINOS experiment
NASA Astrophysics Data System (ADS)
Chen, Rui; Minos Collaboration
2017-01-01
The MINOS experiment is a long-baseline on-axis neutrino oscillation experiment. The two detectors are separated by 734km and optimised for sensitivity to the disappearance of muon neutrinos and antineutrinos delivered by the NuMI beam at Fermilab. The MINOS detectors are magnetised, giving the experiment a unique ability to separate neutrinos and antineutrinos on an event-by-event basis. Thanks to the different possible NuMI beam configurations, MINOS has accumulated 10 . 56 ×1020 POT from a muon neutrino dominated beam and 3 . 36 ×1020 POT from a muon antineutrino enhanced beam. In this talk I will present an analysis of the muon antineutrino interactions collected in both beam configurations. The LSND and MiniBooNE experiments have observed non-standard electron antineutrino appearance in their oscillation analyses. A possible explanation for this is the 3+1 sterile neutrino model where one adds an additional neutrino to the current three-flavour model. MINOS is sensitive to this model through looking at the charged current neutrino and antineutrino energy spectra to probe any deviations from the three-flavour muon neutrino and antineutrino survival probabilities. In this talk, I will present new limits on sterile antineutrinos, using this 3+1 model.
AGM2015: Antineutrino Global Map 2015
NASA Astrophysics Data System (ADS)
Usman, S. M.; Jocher, G. R.; Dye, S. T.; McDonough, W. F.; Learned, J. G.
2015-09-01
Every second greater than 1025 antineutrinos radiate to space from Earth, shining like a faint antineutrino star. Underground antineutrino detectors have revealed the rapidly decaying fission products inside nuclear reactors, verified the long-lived radioactivity inside our planet, and informed sensitive experiments for probing fundamental physics. Mapping the anisotropic antineutrino flux and energy spectrum advance geoscience by defining the amount and distribution of radioactive power within Earth while critically evaluating competing compositional models of the planet. We present the Antineutrino Global Map 2015 (AGM2015), an experimentally informed model of Earth’s surface antineutrino flux over the 0 to 11 MeV energy spectrum, along with an assessment of systematic errors. The open source AGM2015 provides fundamental predictions for experiments, assists in strategic detector placement to determine neutrino mass hierarchy, and aids in identifying undeclared nuclear reactors. We use cosmochemically and seismologically informed models of the radiogenic lithosphere/mantle combined with the estimated antineutrino flux, as measured by KamLAND and Borexino, to determine the Earth’s total antineutrino luminosity at . We find a dominant flux of geo-neutrinos, predict sub-equal crust and mantle contributions, with ~1% of the total flux from man-made nuclear reactors.
NASA Astrophysics Data System (ADS)
Wilhelm, F.; Sanchez, J. P.; Brison, J.-P.; Aoki, D.; Shick, A. B.; Rogalev, A.
2017-06-01
The ferromagnetic superconductor URhGe has been investigated by high field magnetic circular dichroism (XMCD) at the U M4 ,5, Rh L2 ,3, and Ge K edges at 2.1 K and at applied fields up to 17 T. The XMCD performed at the M4 ,5 absorption edges allows us to determine the spectroscopic branching ratio and the 5 f electron contribution to the valence spin-orbit interaction. Combination with polarized neutron diffraction results allows us to derive the individual U orbital and spin moments and the magnetic-dipole contribution
Wang, Liang Germaschewski, K.; Hakim, Ammar H.; Bhattacharjee, A.
2015-01-15
We introduce an extensible multi-fluid moment model in the context of collisionless magnetic reconnection. This model evolves full Maxwell equations and simultaneously moments of the Vlasov-Maxwell equation for each species in the plasma. Effects like electron inertia and pressure gradient are self-consistently embedded in the resulting multi-fluid moment equations, without the need to explicitly solving a generalized Ohm's law. Two limits of the multi-fluid moment model are discussed, namely, the five-moment limit that evolves a scalar pressures for each species and the ten-moment limit that evolves the full anisotropic, non-gyrotropic pressure tensor for each species. We first demonstrate analytically and numerically that the five-moment model reduces to the widely used Hall magnetohydrodynamics (Hall MHD) model under the assumptions of vanishing electron inertia, infinite speed of light, and quasi-neutrality. Then, we compare ten-moment and fully kinetic particle-in-cell (PIC) simulations of a large scale Harris sheet reconnection problem, where the ten-moment equations are closed with a local linear collisionless approximation for the heat flux. The ten-moment simulation gives reasonable agreement with the PIC results regarding the structures and magnitudes of the electron flows, the polarities and magnitudes of elements of the electron pressure tensor, and the decomposition of the generalized Ohm's law. Possible ways to improve the simple local closure towards a nonlocal fully three-dimensional closure are also discussed.
NASA Astrophysics Data System (ADS)
Wang, Liang; Hakim, Ammar H.; Bhattacharjee, A.; Germaschewski, K.
2015-01-01
We introduce an extensible multi-fluid moment model in the context of collisionless magnetic reconnection. This model evolves full Maxwell equations and simultaneously moments of the Vlasov-Maxwell equation for each species in the plasma. Effects like electron inertia and pressure gradient are self-consistently embedded in the resulting multi-fluid moment equations, without the need to explicitly solving a generalized Ohm's law. Two limits of the multi-fluid moment model are discussed, namely, the five-moment limit that evolves a scalar pressures for each species and the ten-moment limit that evolves the full anisotropic, non-gyrotropic pressure tensor for each species. We first demonstrate analytically and numerically that the five-moment model reduces to the widely used Hall magnetohydrodynamics (Hall MHD) model under the assumptions of vanishing electron inertia, infinite speed of light, and quasi-neutrality. Then, we compare ten-moment and fully kinetic particle-in-cell (PIC) simulations of a large scale Harris sheet reconnection problem, where the ten-moment equations are closed with a local linear collisionless approximation for the heat flux. The ten-moment simulation gives reasonable agreement with the PIC results regarding the structures and magnitudes of the electron flows, the polarities and magnitudes of elements of the electron pressure tensor, and the decomposition of the generalized Ohm's law. Possible ways to improve the simple local closure towards a nonlocal fully three-dimensional closure are also discussed.
de Melo, Roger Duarte; Acosta-Avalos, Daniel
2017-02-04
Magnetotactic microorganisms are characterized by swimming in the direction of an applied magnetic field. In nature, two types of swimming polarity have been observed: north-seeking microorganisms that swim in the same direction as the magnetic field, and south-seeking microorganisms that swim in the opposite direction. The present work studies the reversal in the swimming polarity of the multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis following an isolation process using high magnetic fields from magnets. The proportion of north- and south-seeking organisms was counted as a function of the magnetic field intensity used during the isolation of the organisms from sediment. It was observed that the proportion of north-seeking organisms increased when the magnetic field was increased. The magnetic moment for north- and south-seeking populations was estimated using the U-turn method. The average magnetic moment was higher for north- than south-seeking organisms. The results suggest that the reversal of swimming polarity must occur during the isolation process in the presence of high magnetic fields and magnetic field gradients. It is shown for the first time that the swimming polarity reversal depends on the magnetic moment intensity of multicellular magnetotactic prokaryotes, and new studies must be undertaken to understand the role of magnetic moment polarity and oxygen gradients in determination of swimming polarity.
Time-Reversal Symmetry Violation in Molecules Induced by Nuclear Magnetic Quadrupole Moments
NASA Astrophysics Data System (ADS)
Flambaum, V. V.; DeMille, D.; Kozlov, M. G.
2014-09-01
Recent measurements in paramagnetic molecules improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Time-reversal (T) and parity (P) symmetry violation in molecules may also come from their nuclei. We point out that nuclear T, P-odd effects are amplified in paramagnetic molecules containing deformed nuclei, where the primary effects arise from the T, P-odd nuclear magnetic quadrupole moment (MQM). We perform calculations of T, P-odd effects in the molecules TaN, ThO, ThF+, HfF+, YbF, HgF, and BaF induced by MQMs. We compare our results with those for the diamagnetic TlF molecule, where the T, P-odd effects are produced by the nuclear Schiff moment. We argue that measurements in molecules with MQMs may provide improved limits on the strength of T, P-odd nuclear forces, on the proton, neutron, and quark EDMs, on quark chromo-EDMs, and on the QCD θ term and CP-violating quark interactions.
Antineutrino geophysics with liquid scintillator detectors
NASA Astrophysics Data System (ADS)
Rothschild, Casey G.; Chen, Mark C.; Calaprice, Frank P.
Detecting the antineutrinos emitted by the decay of radioactive elements in the mantle and crust could provide a direct measurement of the total abundance of uranium and thorium in the Earth. In calculating the antineutrino flux at specific sites, the local geology of the crust and the background from the world's nuclear power reactors are important considerations. Employing a global crustal map, with type and thickness data, and using recent estimates of the uranium and thorium distribution in the Earth, we calculate the antineutrino event rate for two new neutrino detectors. We show that spectral features allow terrestrial antineutrino events to be identified above reactor antineutrino backgrounds and that the uranium and thorium contributions can be separately determined.
Anomalous magnetic moments as evidence of chiral superconductivity in a Bi/Ni bilayer
NASA Astrophysics Data System (ADS)
Wang, Junhua; Gong, Xinxin; Yang, Guang; Lyu, Zhaozheng; Pang, Yuan; Liu, Guangtong; Ji, Zhongqing; Fan, Jie; Jing, Xiunian; Yang, Changli; Qu, Fanming; Jin, Xiaofeng; Lu, Li
2017-08-01
There have been continuous efforts in searching for unconventional superconductivity in the past five decades. Compared to the well-established d -wave superconductivity in cuprates, the existence of superconductivity with pairing symmetries of other high angular momentum is less conclusive. Bi/Ni epitaxial bilayer is a potential unconventional superconductor with broken time reversal symmetry (TRS), for that it demonstrates superconductivity and ferromagnetism simultaneously at low temperatures. We employ a specially designed superconducting quantum interference device (SQUID) to detect, on the Bi/Ni bilayer, the orbital magnetic moments which are expected if the TRS is broken. An anomalous hysteretic magnetic response is indeed observed in the superconducting state, providing the evidence for the existence of chiral superconducting domains in the material.
Non-Fermi-Liquid Behavior in Metallic Quasicrystals with Local Magnetic Moments
NASA Astrophysics Data System (ADS)
Andrade, Eric C.; Jagannathan, Anuradha; Miranda, Eduardo; Vojta, Matthias; Dobrosavljević, Vladimir
2015-07-01
Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15 , we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures T , leading to a power-law distribution of Kondo temperatures P (TK)˜TKα -1, with a nonuniversal exponent α , in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. For α <1 , the resulting singular P (TK) induces non-Fermi-liquid behavior with diverging thermodynamic responses as T →0 .
Astroid curves of high-moment antiferromagnetic nanoparticles with tunable magnetic properties
NASA Astrophysics Data System (ADS)
Forrester, D. M.; Kovacs, E.; Kürten, K. E.; Kusmartsev, F. V.
2009-04-01
We have determined astroids for high-moment antiferromagnetic nanoparticles (AN), which have been recently discovered and used in numerous biomedical applications. The astroid curves for such a system, which is a stack of two isolated disk-shaped ferromagnetic nanoparticles interacting antiferromagnetically, show the regions in the magnetic field plane where different numbers of minima associated with stable or metastable states may exist. We describe the properties of these ANs and estimate their other characteristic parameters such as magnetic saturation field and exchange antiferrtomagnetic coupling. We argue that the finding of these astroids and the properties of ANs is crucial for the use of ANs in numerous applications and for modeling stable information storage devices.
High-Precision Microwave Spectroscopy of Muonium for Determination of Muonic Magnetic Moment
NASA Astrophysics Data System (ADS)
Torii, H. A.; Higashi, Y.; Higuchi, T.; Matsuda, Y.; Mizutani, T.; Tajima, M.; Tanaka, K. S.; Ueno, Y.; Fukao, Y.; Iinuma, H.; Ikedo, Y.; Kadono, R.; Kawamura, N.; Koda, A.; Kojima, K. M.; Mibe, T.; Miyake, Y.; Nagamine, K.; Nishiyama, K.; Ogitsu, T.; Okubo, R.; Saito, N.; Sasaki, K.; Shimomura, K.; Strasser, P.; Sugano, M.; Toyoda, A.; Ueno, K.; Yamamoto, A.; Yoshida, M.; Ishida, K.; Iwasaki, M.; Kamigaito, O.; Tomono, D.; Kanda, S.; Kubo, K.; Aoki, M.; Torikai, E.; Kawall, D.
2016-02-01
The muonium atom is a system suitable for precision measurements for determination of muon’s fundamental properties as well as for the test of quantum electrodynamics (QED). A microwave spectroscopy experiment of this exotic atom is being prepared at J-PARC, jointly operated by KEK and JAEA in Japan, aiming at an improved relative precision at a level of 10-8 in determination of the muonic magnetic moment. A major improvement of statistical uncertainty is expected with the higher muon intensity of the pulsed beam at J-PARC, while reduction of various sources of systematic uncertainties are being studied: those arising from microwave power fluctuations, magnetic field inhomogeneity, muon stopping distribution and atomic collisional shift of resonance frequencies. Experimental strategy and methods are presented in this paper, with an emphasis on our recent development of apparatuses and evaluation of systematic uncertainties.
Behavior of the critical temperature of Ising thin films with variable surface magnetic moments.
Monroe, James L
2005-01-01
Properties of magnetic thin films are of considerable interest both for applied as well as theoretical reasons. I study the behavior of Ising thin films through the use of layered Bethe lattices and Husimi trees. In particular the behavior of the critical temperature both as a function of the number of layers and as a function of variable magnetic moments of surface spins is presented. The later is motivated by that fact that such variation has been found to occur in physical systems such as Ni and Fe free surfaces and Ni/Co interfaces. The approach used is more accurate than many previously used and most importantly shows a different qualitative behavior of the critical temperature from previous studies.
Valley-contrasting physics in graphene: magnetic moment and topological transport.
Xiao, Di; Yao, Wang; Niu, Qian
2007-12-07
We investigate physical properties that can be used to distinguish the valley degree of freedom in systems where inversion symmetry is broken, using graphene systems as examples. We show that the pseudospin associated with the valley index of carriers has an intrinsic magnetic moment, in close analogy with the Bohr magneton for the electron spin. There is also a valley dependent Berry phase effect that can result in a valley contrasting Hall transport, with carriers in different valleys turning into opposite directions transverse to an in-plane electric field. These effects can be used to generate and detect valley polarization by magnetic and electric means, forming the basis for the valley-based electronics applications.
Local magnetic moments in iron and nickel at ambient and Earth's core conditions
NASA Astrophysics Data System (ADS)
Hausoel, A.; Karolak, M.; Şaşɩoğlu, E.; Lichtenstein, A.; Held, K.; Katanin, A.; Toschi, A.; Sangiovanni, G.
2017-07-01
Some Bravais lattices have a particular geometry that can slow down the motion of Bloch electrons by pre-localization due to the band-structure properties. Another known source of electronic localization in solids is the Coulomb repulsion in partially filled d or f orbitals, which leads to the formation of local magnetic moments. The combination of these two effects is usually considered of little relevance to strongly correlated materials. Here we show that it represents, instead, the underlying physical mechanism in two of the most important ferromagnets: nickel and iron. In nickel, the van Hove singularity has an unexpected impact on the magnetism. As a result, the electron-electron scattering rate is linear in temperature, in violation of the conventional Landau theory of metals. This is true even at Earth's core pressures, at which iron is instead a good Fermi liquid. The importance of nickel in models of geomagnetism may have therefore to be reconsidered.
NASA Astrophysics Data System (ADS)
Pal, Bappaditya; Sarkar, D.; Giri, P. K.
2015-11-01
We report on the room temperature ferromagnetism in the Zn1-xNixO (x = 0, 0.03 and 0.05) nanoparticles (NPs) synthesized by a ball milling technique. X-ray diffraction analysis confirms the single crystalline, wurtzite ZnO structure for the 3% Ni doped ZnO NPs for higher milling time. HRTEM lattice image and SAED pattern show that the doped NPs are single crystalline with a d-spacing of 2.47 Å corresponding to the (1 0 1) plane. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirm the presence of Ni ions inside the ZnO matrix with 2+ valance state. Room temperature magnetic measurements exhibit the hysteresis loop with saturation magnetization (Ms) of 1.6-2.56 (emu/g) and coercive field (Hc) of 260 Oe. Micro-Raman studies illustrate doping/disorder induced additional Raman modes at ∼547, 574 cm-1 in addition to 437 cm-1 peak of pure ZnO. Photoluminescence (PL) spectra and UV-vis absorption measurements demonstrate some modification in the band edge emission and absorption characteristics, respectively. PL spectra also show defect related strong visible emission, which is believed to play a significant role in the FM ordering. These observations highlight the effect of changing defect density on the observed ferromagnetic moment values for the as synthesized Zn1-xNixO NPs. Magnetic interaction is quantitatively analyzed and explained using a bound magnetic polaron model and expected to arise from the intrinsic exchange interaction of Ni ions and OV, Zni defects. Systemic studies on the structural, magnetic, and optical properties reveal that both the nature of the defects as well as Ni2+ ions are significant ingredients behind attaining high moment as well as high ordering temperature in Ni doped ZnO NPs.
NASA Astrophysics Data System (ADS)
Okabayashi, Jun; Sukegawa, Hiroaki; Wen, Zhenchao; Inomata, Koichiro; Mitani, Seiji
2013-09-01
Perpendicular magnetic anisotropy (PMA) in Heusler alloy Co2FeAl thin films sharing an interface with a MgO layer is investigated by angular-dependent x-ray magnetic circular dichroism. Orbital and spin magnetic moments are deduced separately for Fe and Co 3d electrons. In addition, the PMA energies are estimated using the orbital magnetic moments parallel and perpendicular to the film surfaces. We found that PMA in Co2FeAl is determined mainly by the contribution of Fe atoms with large orbital magnetic moments, which are enhanced at the interface between Co2FeAl and MgO. Furthermore, element specific magnetization curves of Fe and Co are found to be similar, suggesting the existence of ferromagnetic coupling between Fe and Co PMA directions.
Grange, Joseph M.
2013-01-01
This dissertation presents the first measurement of the muon antineutrino charged current quasi-elastic double-differential cross section. These data significantly extend the knowledge of neutrino and antineutrino interactions in the GeV range, a region that has recently come under scrutiny due to a number of conflicting experimental results. To maximize the precision of this measurement, three novel techniques were employed to measure the neutrino background component of the data set. Representing the first measurements of the neutrino contribution to an accelerator-based antineutrino beam in the absence of a magnetic field, the successful execution of these techniques carry implications for current and future neutrino experiments.
The permanent electric dipole moments and magnetic g factors of uranium monoxide
NASA Astrophysics Data System (ADS)
Heaven, Michael C.; Goncharov, Vasiliy; Steimle, Timothy C.; Ma, Tongmei; Linton, Colan
2006-11-01
Permanent electric dipole moments and magnetic g factors for uranium monoxide (UO) have been determined from analyses of optical Stark and Zeeman spectra recorded at a spectral resolution that approaches the natural linewidth limit. Numerous branch features in the previously characterized [L. A. Kaledin et al., J. Mol. Spectrosc. 164, 27 (1994)] (0,0) [18403]5-X(1)4 and (0,0) [18404]5-X(1)4 electronic transitions were recorded in the presence of tunable static electric (Stark effect) or magnetic (Zeeman effect) fields. The lines exhibited unusually large Zeeman tuning effects. A ligand field model and an ab initio electronic structure calculation [R. Tyagi, Ph.D. thesis, The Ohio State University (2005)] were used to interpret the ground state properties. The results indicate that the low energy electronic states of UO are sufficiently ionic for the meaningful application of ligand field theory models. The dipole moments and g factors were distinctly different for the three electronic states examined, which implies that these properties may be used to deduce the underlying electronic state configurations.
NASA Astrophysics Data System (ADS)
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-01
The most compelling possibility for a new law of nature beyond the four fundamental forces comprising the standard model of high-energy physics is the discrepancy between measurements and calculations of the muon anomalous magnetic moment. Until now a key part of the calculation, the hadronic light-by-light contribution, has only been accessible from models of QCD, the quantum description of the strong force, whose accuracy at the required level may be questioned. A first principles calculation with systematically improvable errors is needed, along with the upcoming experiments, to decisively settle the matter. For the first time, the form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in such a framework, lattice QCD +QED and QED. A nonperturbative treatment of QED is used and checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed for which statistically significant signals are obtained. Initial results are promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-09
The most compelling possibility for a new law of nature beyond the four fundamental forces comprising the standard model of high-energy physics is the discrepancy between measurements and calculations of the muon anomalous magnetic moment. Until now a key part of the calculation, the hadronic light-by-light contribution, has only been accessible from models of QCD, the quantum description of the strong force, whose accuracy at the required level may be questioned. A first principles calculation with systematically improvable errors is needed, along with the upcoming experiments, to decisively settle the matter. For the first time, the form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in such a framework, lattice QCD+QED and QED. A nonperturbative treatment of QED is used and checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed for which statistically significant signals are obtained. Initial results are promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
NASA Astrophysics Data System (ADS)
Brechet, Sylvain
2013-03-01
Spin caloritronics is mainly focused on studying the effects of a temperature gradient on the time evolution of the local spin average of a classical system. In many experimental situations, the system can be treated as a classical continuum with magnetisation on the scale of interest where the quantum fluctuations average out and the underlying microscopic structure is smoothed out. Here, we establish a clear classical formalism describing the thermodynamics of a matter continuum with magnetic moments interacting with external electromagnetic fields. Taking into account the chemical nature of the current densities - such as the current density of magnetic moments - and stress tensors leads to three types of dissipation terms: scalars, vectors and pseudo-vectors. The scalar terms account for the chemical reactivities, the vectorial terms account for the transport and pseudo-vectorial terms account for the relaxation. The vectorial phenomenological relations establish notably the Spin Seebeck effect first observed by Uchida and Saitoh. The pseudo-vectorial phenomenological relations establish in particular the Landau-Lifschitz relaxation of the magnetisation.
MSSM extension with a mirror fourth generation, neutrino magnetic moments, and CERN LHC signatures
Ibrahim, Tarek; Nath, Pran
2008-10-01
Recent analyses have shown that a sequential fourth generation can be consistent with precision electroweak data. We consider the possibility that the new generation could be a mirror generation with V+A rather than V-A interactions. Specifically we consider an extension of the minimal supersymmetric standard model with a light mirror generation. Implications of this extension are explored. One consequence is an enhancement of the {tau} neutrino magnetic moment by several orders of magnitude consistent with the current limits on the magnetic moment of the {tau}. The masses of the mirror generation arise due to electroweak symmetry breaking, and if a mirror generation exists its mass spectrum must lie below a TeV, and thus should be discovered at the LHC. Mirror particles and mirror sparticles produce many characteristic signatures which should be detectable at the LHC. Heavy Higgs boson decays into mirror particles and an analysis of the forward-backward asymmetries can distinguish a mirror generation from a sequential fourth generation. The validity of the model can thus be tested at the LHC. A model of the type discussed here could arise from a more unified structure such as grand unification or strings where a mirror generation escapes the survival hypothesis, i.e., a generation and a mirror generation do not tie up to acquire a mass of size M{sub GUT} or M{sub string} due to a symmetry, and thus remain massless down to the electroweak scale.
Magnetic g_e-FACTORS and Electric Dipole Moments of Lanthanide Monoxides: PrO
NASA Astrophysics Data System (ADS)
Wang, Hailing; Steimle, Timothy C.; Linton, Colan
2009-06-01
The very complex optical spectra of the lanthanide monoxides are caused by the insensitivity of the electronic energies to the numerous possible arrangements of the Ln^{2+} electrons in the 4f and 6s orbitals. Disentangling the complex optical spectra may be aided by using simple Ligand Field Theory(LFT) to establish the global electronic structure for the low-lying electronic states. A comparison of experimentally determined permanent electric dipole moments, μ_{el}, and magnetic dipole moments, μ_{m}, is an effective means of sorting this myriad of states and assessing the quality of LFT and other electronic structure methodologies. Here we report on the determination of the permanent electric dipole moments, μ_{el}, and magnetic g{_e}-factors for the X_{2}(Ω = 4.5) and [18.1] (Ω = 5.5) states of PrO from the analysis of the optical Stark and Zeeman spectra. The g_{e}-factors are compared with those computed using wavefunctions predicted from ligand field theory. The μ_{el} value for the X_{2}(Ω = 4.5) state is compared to ab initio, and density functional predictions and with the experimental values of other lanthanide monoxides. A phenomenological fit of μ_{el} for the entire series of LnO is used to predict μ_{el} for the isovalent actinide monoxide series. Carette, P.,; Hocquet,A. J. Mol. Spectrosc. 131 301, 1988. Dolg, M.; Stoll, H. Theor. Chim. Acta. 75,369, 1989. Wu, Z.; Guan, W. Meng, J. Su, Z. J. Cluster Science 18 444, 2007.
NASA Astrophysics Data System (ADS)
van Rijssel, Jos; Kuipers, Bonny W. M.; Erné, Ben H.
2015-04-01
High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal distribution of the magnetic dipole moment. Here, we test this assumption for different types of superparamagnetic iron oxide nanoparticles in the 5-20 nm range, by multimodal fitting of magnetization curves using the MINORIM inversion method. The particles are studied while in dilute colloidal dispersion in a liquid, thereby preventing hysteresis and diminishing the effects of magnetic anisotropy on the interpretation of the magnetization curves. For two different types of well crystallized particles, the magnetic distribution is indeed log-normal, as expected from the physical size distribution. However, two other types of particles, with twinning defects or inhomogeneous oxide phases, are found to have a bimodal magnetic distribution. Our qualitative explanation is that relatively low fields are sufficient to begin aligning the particles in the liquid on the basis of their net dipole moment, whereas higher fields are required to align the smaller domains or less magnetic phases inside the particles.
Rashba Interaction and Local Magnetic Moments in a Graphene-BN Heterostructure Intercalated with Au
NASA Astrophysics Data System (ADS)
O'Farrell, E. C. T.; Tan, J. Y.; Yeo, Y.; Koon, G. K. W.; Ã-zyilmaz, B.; Watanabe, K.; Taniguchi, T.
2016-08-01
We intercalate a van der Waals heterostructure of graphene and hexagonal boron nitride with Au, by encapsulation, and show that the Au at the interface is two dimensional. Charge transfer upon current annealing indicates the redistribution of the Au and induces splitting of the graphene band structure. The effect of an in-plane magnetic field confirms that the splitting is due to spin splitting and that the spin polarization is in the plane, characteristic of a Rashba interaction with a magnitude of approximately 25 meV. Consistent with the presence of an intrinsic interfacial electric field we show that the splitting can be enhanced by an applied displacement field in dual gated samples. A giant negative magnetoresistance, up to 75%, and a field induced anomalous Hall effect at magnetic fields <1 T are observed. These demonstrate that the hybridized Au has a magnetic moment and suggests the proximity to the formation of a collective magnetic phase. These effects persist close to room temperature.
Is Deuterium Nuclear Fusion Catalyzed by Antineutrinos?
NASA Astrophysics Data System (ADS)
Shomer, Isaac
2010-02-01
The hypothesis of Fischbach and Jenkins that neutrinos emitted from the sun accelerate radioactive decay is noted. It is thought that neutrinos accelerate beta decay by reacting with neutron-rich nuclides to form a beta particle and a daughter product, with no antineutrino emitted. Conversely, it is proposed that antineutrinos can react with proton-rich nuclides to cause positron decay, with no neutrino emitted. It is also proposed that the nuclear fusion of the hydrogen bomb is triggered not only by the energy of the igniting fission bomb, but by the antineutrinos created by the rapid beta decay of the daughter products in the fission process. The contemplated mechanism for antineutrino initiated fusion is the following: 1. The antineutrinos from the fission daughter products cause positron decay of deuterium by the process outlined above. 2. In a later fusion step, these positrons subsequently react with neutrons in deuterium to create antineutrinos. Electrons are unavailable to annihilate positrons in the plasma of the hydrogen bomb. 3. These antineutrinos thereafter react with more deuterium to form positrons, thereby propagating a chain reaction. )
NASA Astrophysics Data System (ADS)
Beach, G. S. D.; Berkowitz, A. E.; Parker, F. T.; Smith, David J.
2001-07-01
Multilayers consisting of discontinuous metal layers with native oxide surfaces have been fabricated using CoxFe100-x alloys ranging in composition from pure Co to pure Fe. For the Fe-containing compositions, the composites are magnetically soft with resistivities in the range of 100 to 2000 μΩ cm. Mössbauer spectroscopy indicates a magnetically ordered Fe-oxide component, and the magnetic moment of the oxide phase for pure Fe/native oxide multilayers has been determined.
Zatsiupa, A.A.; Bashkirov, L.A.; Troyanchuk, I.O.; Petrov, G.S.; Galyas, A.I.; Lobanovsky, L.S.; Truhanov, S.V.
2014-04-01
Magnetic susceptibility for ferrite Bi{sub 25}FeO{sub 39} is measured at 5–950 K in the magnetic field of 0.86 T. It is shown that Bi{sub 25}FeO{sub 39} is paramagnetic in the temperature range 5−950 K. The saturation magnetization is equal to 5.04μ{sub B} per formula unit at 5 K in a magnetic field of 10 T. It is found that at 5−300 K the effective magnetic moment of Fe{sup 3+} ions in Bi{sub 25}FeO{sub 39} is equal to 5.82μ{sub B}. - Graphical abstract: The dependence of the magnetization (n, μ{sub B}) on the magnetic field for one formula unit of Bi{sub 25}FeO{sub 39} at 5 K. - Highlights: • Magnetic susceptibility for Bi{sub 25}FeO{sub 39} is measured at 5–950 K in the magnetic field of 0.86 T. • It is shown that Bi{sub 25}FeO{sub 39} is paramagnetic in the temperature range 5−950 K. • The saturation magnetization is equal to 5.04μ{sub B} per formula unit at 5 K in a magnetic field of 10 T.
Fradin, Cécile
2013-01-01
Magnetotactic bacteria possess organelles called magnetosomes that confer a magnetic moment on the cells, resulting in their partial alignment with external magnetic fields. Here we show that analysis of the trajectories of cells exposed to an external magnetic field can be used to measure the average magnetic dipole moment of a cell population in at least five different ways. We apply this analysis to movies of Magnetospirillum magneticum AMB-1 cells, and compare the values of the magnetic moment obtained in this way to that obtained by direct measurements of magnetosome dimension from electron micrographs. We find that methods relying on the viscous relaxation of the cell orientation give results comparable to that obtained by magnetosome measurements, whereas methods relying on statistical mechanics assumptions give systematically lower values of the magnetic moment. Since the observed distribution of magnetic moments in the population is not sufficient to explain this discrepancy, our results suggest that non-thermal random noise is present in the system, implying that a magnetotactic bacterial population should not be considered as similar to a paramagnetic material. PMID:24349185
Nadkarni, Rohan; Barkley, Solomon; Fradin, Cécile
2013-01-01
Magnetotactic bacteria possess organelles called magnetosomes that confer a magnetic moment on the cells, resulting in their partial alignment with external magnetic fields. Here we show that analysis of the trajectories of cells exposed to an external magnetic field can be used to measure the average magnetic dipole moment of a cell population in at least five different ways. We apply this analysis to movies of Magnetospirillum magneticum AMB-1 cells, and compare the values of the magnetic moment obtained in this way to that obtained by direct measurements of magnetosome dimension from electron micrographs. We find that methods relying on the viscous relaxation of the cell orientation give results comparable to that obtained by magnetosome measurements, whereas methods relying on statistical mechanics assumptions give systematically lower values of the magnetic moment. Since the observed distribution of magnetic moments in the population is not sufficient to explain this discrepancy, our results suggest that non-thermal random noise is present in the system, implying that a magnetotactic bacterial population should not be considered as similar to a paramagnetic material.
Reactor monitoring and safeguards using antineutrino detectors
Bowden, N S
2008-09-07
Nuclear reactors have served as the antineutrino source for many fundamental physics experiments. The techniques developed by these experiments make it possible to use these very weakly interacting particles for a practical purpose. The large flux of antineutrinos that leaves a reactor carries information about two quantities of interest for safeguards: the reactor power and fissile inventory. Measurements made with antineutrino detectors could therefore offer an alternative means for verifying the power history and fissile inventory of a reactors, as part of International Atomic Energy Agency (IAEA) and other reactor safeguards regimes. Several efforts to develop this monitoring technique are underway across the globe.
NASA Astrophysics Data System (ADS)
Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.
2012-08-01
A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters
Meyer, Jennifer; Tombers, Matthias; Wüllen, Christoph van; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-14
We present size dependent spin and orbital magnetic moments of cobalt (Co{sub n}{sup +}, 8 ≤ n ≤ 22), iron (Fe{sub n}{sup +}, 7 ≤ n ≤ 17), and nickel cluster (Ni{sub n}{sup +}, 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law “per cluster diameter,” ∼n{sup −1/3}, that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of “primary” and “secondary” (induced) orbital moments is invoked for interpretation.
NASA Technical Reports Server (NTRS)
Russell, C. T.; Coleman, P. J., Jr.; Goldstein, B. E.
1982-01-01
Apollo 15 and 16 subsatellite fluxgate magnetometer data have been analyzed for all intervals in which the moon was in the lobes of the geomagnetic tail to obtain an improved estimate of the average magnitude of the induced dipole moment of the moon. The resulting set of estimates yields an induced magnetic moment of -4.23 x 10 to the 22nd Gauss-cu cm per Gauss of applied field, corresponding to a G-factor of -0.008 + or - 0.001. These measurements do not place strong constraints on the conductivity of the lunar core. The observed effects would be detected as long as the core conductivity was greater than about 10 mho/m. If the outer cool layers of the moon that are at temperatures below the effective Curie point contain little or no free iron, then these measurements are consistent with the presence of a conducting core whose radius is slightly larger than 400 km. If these outer layers of the moon contain significant amounts of free iron and hence exhibit the paramagnetism expected in such a situation the core size could be even greater.
Covariant Spectator Theory of np scattering: Deuteron magnetic moment and form factors
Gross, Franz L.
2014-06-01
The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small $P$-state components gives 0.864(2) These are about 1\\% larger than the measured value of the moment, 0.857 n.m., giving a new prediction for the size of the $\\rho\\pi\\gamma$ exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulae for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.
Four-flavour leading-order hadronic contribution to the muon anomalous magnetic moment
Burger, Florian; Feng, Xu; Hotzel, Grit; ...
2014-02-24
We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, aμhvp, arising from quark-connected Feynman graphs. It is based on ensembles featuring Nf=2+1+1 dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of amore » μhvp. The final result involving an estimate of the systematic uncertainty aμhvp=6.74 (21)(18) 10-8 shows a good overall agreement with these computations.« less
Mass and magnetic dipole moment of negative-parity heavy baryons with spin-3/2
NASA Astrophysics Data System (ADS)
Azizi, K.; Sundu, H.
2017-01-01
We calculate the mass and residue of the heavy spin-3/2 negative-parity baryons with single heavy bottom or charm quark by use of a two-point correlation function. We use the obtained results to investigate the diagonal radiative transitions among the baryons under consideration. In particular, we compute corresponding transition form factors via light cone QCD sum rules, which are then used to obtain the magnetic dipole moments of the heavy spin-3/2 negative-parity baryons. We remove the pollutions coming from the positive-parity spin-3/2 and positive/negative-parity spin-1/2 baryons by constructing sum rules for different Lorentz structures. We compare the results obtained with the existing theoretical predictions.
Final results on the neutrino magnetic moment from the MUNU experiment
NASA Astrophysics Data System (ADS)
Daraktchieva, Z.; Amsler, C.; Avenier, M.; Broggini, C.; Busto, J.; Cerna, C.; Juget, F.; Koang, D. H.; Lamblin, J.; Lebrun, D.; Link, O.; Puglierin, G.; Stutz, A.; Tadsen, A.; Vuilleumier, J.-L.; Zacek, V.; MUNU Collaboration
2005-06-01
The MUNU detector was designed to study νbaree- elastic scattering at low energy. The central component is a Time Projection Chamber filled with CF4 gas, surrounded by an anti-Compton detector. The experiment was carried out at the Bugey (France) nuclear reactor. In this Letter we present the final analysis of the data recorded at 3 bar and 1 bar pressure. Both the energy and the scattering angle of the recoil electron are measured. From the 3 bar data a new upper limit on the neutrino magnetic moment μeshort < 9 ×10-11μB at 90% CL was derived. At 1 bar electron tracks down to 150 keV were reconstructed, demonstrating the potentiality of the experimental technique for future applications in low energy neutrino physics.
Final results on the neutrino magnetic moment from the MUNU experiment
NASA Astrophysics Data System (ADS)
Munu Collaboration; Daraktchieva, Z.; Amsler, C.; Avenier, M.; Broggini, C.; Busto, J.; Cerna, C.; Juget, F.; Koang, D. H.; Lamblin, J.; Lebrun, D.; Link, O.; Puglierin, G.; Stutz, A.; Tadsen, A.; Vuilleumier, J.-L.; Zacek, V.
2005-06-01
The MUNU detector was designed to study νe elastic scattering at low energy. The central component is a Time Projection Chamber filled with CF4 gas, surrounded by an anti-Compton detector. The experiment was carried out at the Bugey (France) nuclear reactor. In this Letter we present the final analysis of the data recorded at 3 bar and 1 bar pressure. Both the energy and the scattering angle of the recoil electron are measured. From the 3 bar data a new upper limit on the neutrino magnetic moment μeshort<9×10μ at 90% CL was derived. At 1 bar electron tracks down to 150 keV were reconstructed, demonstrating the potentiality of the experimental technique for future applications in low energy neutrino physics.
The muon magnetic moment in the 2HDM: complete two-loop result
NASA Astrophysics Data System (ADS)
Cherchiglia, Adriano; Kneschke, Patrick; Stöckinger, Dominik; Stöckinger-Kim, Hyejung
2017-01-01
We study the 2HDM contribution to the muon anomalous magnetic moment a μ and present the complete two-loop result, particularly for the bosonic contribution. We focus on the Aligned 2HDM, which has general Yukawa couplings and contains the type I, II, X, Y models as special cases. The result is expressed with physical parameters: three Higgs boson masses, Yukawa couplings, two mixing angles, and one quartic potential parameter. We show that the result can be split into several parts, each of which has a simple parameter dependence, and we document their general behavior. Taking into account constraints on parameters, we find that the full 2HDM contribution to a μ can accommodate the current experimental value, and the complete two-loop bosonic contribution can amount to (2⋯4) × 10-10, more than the future experimental uncertainty.
Neutrino transition magnetic moments within the non-standard neutrino-nucleus interactions
NASA Astrophysics Data System (ADS)
Papoulias, D. K.; Kosmas, T. S.
2015-07-01
Tensorial non-standard neutrino interactions are studied through a combined analysis of nuclear structure calculations and a sensitivity χ2-type of neutrino events expected to be measured at the COHERENT experiment, recently planned to operate at the Spallation Neutron Source (Oak Ridge). Potential sizeable predictions on transition neutrino magnetic moments and other electromagnetic parameters, such as neutrino milli-charges, are also addressed. The non-standard neutrino-nucleus processes, explored from nuclear physics perspectives within the context of quasi-particle random phase approximation, are exploited in order to estimate the expected number of events originating from vector and tensor exotic interactions for the case of reactor neutrinos, studied with TEXONO and GEMMA neutrino detectors.
Concentric transmon qubit featuring fast tunability and an anisotropic magnetic dipole moment
NASA Astrophysics Data System (ADS)
Braumüller, Jochen; Sandberg, Martin; Vissers, Michael R.; Schneider, Andre; Schlör, Steffen; Grünhaupt, Lukas; Rotzinger, Hannes; Marthaler, Michael; Lukashenko, Alexander; Dieter, Amadeus; Ustinov, Alexey V.; Weides, Martin; Pappas, David P.
2016-01-01
We present a planar qubit design based on a superconducting circuit that we call concentric transmon. While employing a straightforward fabrication process using Al evaporation and lift-off lithography, we observe qubit lifetimes and coherence times in the order of 10 μ s . We systematically characterize loss channels such as incoherent dielectric loss, Purcell decay and radiative losses. The implementation of a gradiometric SQUID loop allows for a fast tuning of the qubit transition frequency and therefore for full tomographic control of the quantum circuit. Due to the large loop size, the presented qubit architecture features a strongly increased magnetic dipole moment as compared to conventional transmon designs. This renders the concentric transmon a promising candidate to establish a site-selective passive direct Z ̂ coupling between neighboring qubits, being a pending quest in the field of quantum simulation.
Using magnetic moments to study the nuclear structure of I{>=} 2 states
Torres, D. A.
2013-05-06
The experimental study of magnetic moments for nuclear states near the ground state, I{>=} 2, provides a powerful tool to test nuclear structure models. Traditionally, the use of Coulomb excitation reactions have been utilized to study low spin states, mostly I= 2. The use of alternative reaction channels, such as {alpha} transfer, for the production of radioactive species that, otherwise, will be only produced in future radioactive beam facilities has proved to be an alternative to measure not only excited states with I > 2, but to populate and study long-live radioactive nuclei. This contribution will present the experimental tools and challenges for the use of the transient field technique for the measurement of g factors in nuclear states with I{>=} 2, using Coulomb excitation and {alpha}-transfer reactions. Recent examples of experimental results near the N= 50 shell closure, and the experimental challenges for future implementations with radioactive beams, will be discussed.
Enhanced sensitivities for the searches of neutrino magnetic moments through atomic ionization.
Wong, Henry T; Li, Hau-Bin; Lin, Shin-Ted
2010-08-06
A new detection channel on atomic ionization for possible neutrino electromagnetic interactions is identified and studied. Significant sensitivity enhancement is demonstrated when the energy transfer to the target is of the atomic-transition scale. The interaction cross section induced by neutrino magnetic moments (μ(ν)) is evaluated with the equivalent photon method. A new limit of μ(ν)(ν[over ¯](e))<1.3×10(-11) μ(B) at 90% confidence level is derived by using current reactor neutrino data. Potential reaches for future experiments are explored. Experiments with sub-keV sensitivities can probe μ(ν) to 10(-13) μ(B). Positive observations of μ(ν) in this range would imply that neutrinos are Majorana particles.
Using magnetic moments to study the nuclear structure of I ≥ 2 states
NASA Astrophysics Data System (ADS)
Torres, D. A.
2013-05-01
The experimental study of magnetic moments for nuclear states near the ground state, I ≥ 2, provides a powerful tool to test nuclear structure models. Traditionally, the use of Coulomb excitation reactions have been utilized to study low spin states, mostly I = 2. The use of alternative reaction channels, such as α transfer, for the production of radioactive species that, otherwise, will be only produced in future radioactive beam facilities has proved to be an alternative to measure not only excited states with I > 2, but to populate and study long-live radioactive nuclei. This contribution will present the experimental tools and challenges for the use of the transient field technique for the measurement of g factors in nuclear states with I ≥ 2, using Coulomb excitation and α-transfer reactions. Recent examples of experimental results near the N = 50 shell closure, and the experimental challenges for future implementations with radioactive beams, will be discussed.
Spin polarization effects on magnetic dipole moment of 153,155Eu
NASA Astrophysics Data System (ADS)
Hoşgör, Gamze; Yakut, Hakan; Tabar, Emre
2017-02-01
Using the Quasiparticle Phonon Nuclear Model (QPNM) and taking into account the spin-spin interaction the effects of the spin polarization on the intrinsic magnetic moments (gK) of 153-155Eu isotopes have been studied. Our calculations indicated that because of the spin polarization, the spin gyromagnetic factors (gs) of the nucleons in the nucleus reduce noticeable from its free nucleon value and the spin-spin interactions play an important role in the renormalization (gse f f .) of the gs factors. A very good reproduction of the phenomenological quenching of gs factor from its free values (gse f f≅0.6 -0.7 gsf r e e) is obtained. The calculated values of effective gse f f and gK are also in fair agreementwith the experiment data.
Kumar, Ashok; Scott, J. F.; Katiyar, R. S.
2011-01-01
Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm3 at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO3 (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (−E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α = 8.5 × 10−12 sm−1. PMID:21901050
Kumar, Ashok; Scott, J F; Katiyar, R S
2011-08-08
Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm(3) at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO(3) (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (-E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α = 8.5 × 10(-12) sm(-1).
Blum, T.; Boyle, P. A.; Izubuchi, T.; ...
2016-06-08
Here we report the first lattice QCD calculation of the hadronic vacuum polarization (HVP) disconnected contribution to the muon anomalous magnetic moment at physical pion mass. The calculation uses a refined noise-reduction technique that enables the control of statistical uncertainties at the desired level with modest computational effort. Measurements were performed on the 483×96 physical-pion-mass lattice generated by the RBC and UKQCD Collaborations. In conclusion, we find the leading-order hadronic vacuum polarization amore » $$HVP(LO)disc\\atop{μ}$$=-9.6(3.3)(2.3)×10-10, where the first error is statistical and the second systematic.« less
Four-flavour leading-order hadronic contribution to the muon anomalous magnetic moment
Burger, Florian; Feng, Xu; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B.
2014-02-24
We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, aμ^{hvp}, arising from quark-connected Feynman graphs. It is based on ensembles featuring N_{f}=2+1+1 dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of a μ^{hvp}. The final result involving an estimate of the systematic uncertainty a_{μ}^{hvp}=6.74 (21)(18) 10^{-8} shows a good overall agreement with these computations.
Octet magnetic moments and the Coleman-Glashow sum rule violation in the chiral quark model
NASA Astrophysics Data System (ADS)
Dahiya, Harleen; Gupta, Manmohan
2002-09-01
Baryon octet magnetic moments when calculated within the chiral quark model, incorporating the orbital angular momentum as well as the quark sea contribution through the Cheng-Li mechanism, not only show improvement over the nonrelativistic quark model results but also give a nonzero value for the right-hand side of the Coleman-Glashow sum rule. When effects due to spin-spin forces between constituent quarks as well as ``mass adjustments'' due to confinement are added, it leads to an excellent fit for the case of p,Σ+, Ξo and violation of the Coleman-Glashow sum rule, whereas in almost all the other cases the results are within 5% of the data.
Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)
White, B. D.; Yazici, D.; Ho, P. -C.; ...
2015-07-20
Here, we report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ~6.7- 6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya- Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order;more » however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.« less
Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)
NASA Astrophysics Data System (ADS)
White, B. D.; Yazici, D.; Ho, P.-C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.
2015-08-01
We report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ˜6.7-6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya-Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4 f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order; however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.
Solovyev, I.V. ); Liechtenstein, A.I. ); Gubanov, V.A. ); Antropov, V.P. ); Andersen, O.K. )
1991-06-15
The linear-muffin-tin-orbital method is generalized to the case of relativistic and spin-polarized self-consistent band calculations. Our formalism is analogous to the standard orthogonal--linear-muffin-tin-orbital formalism, except that the potential functions and the potential parameters are now matrices. The method is used to perform density-functional calculations for fcc plutonium with different atomic volumes. The formation of spin and orbital magnetic moments, as well as the changes in the energy bands for volume changes corresponding to the {alpha}-{delta} transition, are investigated. The calculated magnetic moments agree quite well with the experimental ones.
Continuous control of local magnetic moment by applied electric field in multiferroics Ba2CoGe2O7
NASA Astrophysics Data System (ADS)
Soda, Minoru; Hayashida, Shohei; Roessli, Bertrand; Mânsson, Martin; White, Jonathan S.; Matsumoto, Masashige; Shiina, Ryousuke; Masuda, Takatsugu
2016-09-01
Ba2CoGe2O7 exhibits a collinear-antiferromagnetic structure with the easy axis along <100 > directions and an antiferroelectric order with the polarization axis along the [001] direction. By applying the electric field the magnetic moment rotates from <100 > to [110] directions and, simultaneously, the antiferroelectric state changes to the ferroelectric state gradually. This magnetoelectric effect, i.e., continuous control of the local magnetic moment by the electric field, is quantitatively explained by the Hamiltonian including the dielectric energy.
Sun, X; Wang, B; Pratt, A; Yamauchi, Y
2014-07-21
The geometric, electronic, and magnetic structures of a manganese phthalocyanine (MnPc) molecule on an antiferromagnetic IrMn(100) surface are studied by density functional theory calculations. Two kinds of orientation of the adsorbed MnPc molecule are predicted to coexist due to molecular self-assembly on the surface-a top-site geometry with the Mn-N bonds aligned along the ⟨100⟩ direction, and a hollow-site orientation in which the Mn-N bonds are parallel to the ⟨110⟩ direction. The MnPc molecule is antiferromagnetically coupled to the substrate at the top site with a slight reduction in the magnetic moment of the Mn atom of the MnPc molecule (Mnmol). In contrast, the magnetic moment of the Mnmol is enhanced to 4.28 μB at the hollow site, a value larger than that in the free MnPc molecule (3.51 μB). Molecular distortion induced by adsorption is revealed to be responsible for the enhancement of the magnetic moment. Furthermore, the spin polarization of the Mnmol atom at around the Fermi level is found to change from negative to positive through an elongation of the Mn-N bonds of the MnPc. We propose that a reversible switch of the low/high magnetic moment and negative/positive spin polarization might be realized through some mechanical engineering methods.
Satoh, Akira; Ozaki, Masataka
2006-06-15
We have investigated the influence of the magnetic field strength, shear rate, and rotational Brownian motion on transport coefficients such as viscosity and diffusion coefficient, and also on the orientational distributions of rodlike particles of a dilute colloidal dispersion. The rodlike particle is modeled as a magnetic spheroidal particle which has a magnetic moment normal to the particle axis; such a particle may typically be a hematite particle. In the present study, an external magnetic field is applied in the direction normal to the shear plane of a simple shear flow. The basic equation of the orientational distribution function has been derived from the balance of torques and solved numerically. The results obtained here are summarized as follows. Although the orientational distribution function shows a sharp peak in the shear flow direction for a very strong magnetic field, such a peak is not restricted to the field direction alone, but continues in every direction of the shear plane. This is due to the characteristic particle motion that the particle can rotate around the axis of the magnetic moment in the shear plane, although the magnetic moment nearly points to the magnetic field direction. This particle motion in the shear plane causes negative values of the viscosity due to the magnetic field. The viscosity decreases, attains a minimum value, and then converges to zero as the field strength increases. Additionally, the diffusion coefficient is significantly influenced by such characteristic particle motion in the shear plane for a strong magnetic field.
Enhancement of the Co magnetic moment in bcc Co1-xMnx on MgO
NASA Astrophysics Data System (ADS)
Snow, Ryan; Bhatkar, Harsh; N'diaye, Alpha; Arenholz, Elke; Idzerda, Yves; Montana State University Team; Lawrence Berkeley National Laboratries Team
Using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (MCD), we show that the elemental Co moment for MBE grown thin films of bcc Co1-xMnx grown on MgO(001) is enhanced by 40% to a maximum value of 2.1 μB at x =0.24. The net Mn moment is found to align parallel with Co for all concentrations and remains roughly constant until x =0.3, then drops steadily, up to x =0.7, where the total moment of the film abruptly collapses to zero. Using a low-concentration Mn moment of 3.0 μB, the average magnetization lies directly on the Slater-Pauling (SP) curve for concentrations up to about x =.25, where it reaches a maximum moment of 2.3 μB /atom. This peak is slightly shifted and the slope is steeper on the high-Mn concentration side of the peak relative to the standard SP curve. This is in stark contrast to the fcc CoMn and hcp CoCr bulk behavior which shows only a rapid total moment reduction with Mn concentration. This material is based upon work supported by the National Science Foundation under Grant ECCS-1542210. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Con.
NASA Astrophysics Data System (ADS)
Liu, Feng; Li, Shaoping; Bai, Daniel; Wang, James; Li, Zhanjie; Han, Dehua; Pan, Tao; Mao, Sining
2012-04-01
High resolution magnetic force microscopy (MFM) imaging with high coercivity probes on perpendicular magnetic recording (PMR) writers directly characterizes magnetic field contour for the writer main pole as well as its shields' magnetic state. Evolution of write bubble and return field was analyzed by MFM imaging in dynamic phase detection scheme. Different write field components and their out of plane second order derivatives were calculated via finite element modeling. The MFM imaged write field distribution correlates well with the PMR writer out of plane write field component. Magnetic responses of the PMR writer main pole, trailing and side shields are quantified. The trailing and side shields exhibit complicated magnetic saturation behaviors comparing with the PMR writer pole. The side shield's magnetic response is dependent upon its initial equilibrium state.
NASA Astrophysics Data System (ADS)
Boda, Aalu; Kumar, D. Sanjeev; Sankar, I. V.; Chatterjee, Ashok
2016-11-01
The problem of a parabolically confined two-dimensional semiconductor GaAs quantum dot with two interacting electrons in the presence of an external magnetic field and the spin-Zeeman interaction is studied using a method of numerical diagonalization. The energy spectrum is calculated as a function of the magnetic field. The magnetic moment (M) and the magnetic susceptibility (χ) show zero temperature diamagnetic peaks due to the exchange induced singlet-triplet transitions. The position and the number of these peaks depend both on the confinement strength of the quantum dot and the strength of the electron-electron interaction (β) .
Synthesis of high magnetic moment soft magnetic nanocomposite powders for RF filters and antennas
NASA Astrophysics Data System (ADS)
Chinnasamy, Chins; Malallah, Yaaqoub; Jasinski, Melania M.; Daryoush, Afshin S.
2015-04-01
Fe60Co40 alloy nanoparticles with an average particle size of 30 nm were successfully synthesized in gram scale batches using the modified polyol process. The X-ray diffraction and microstructure studies clearly show the formation of the alloy nanoparticles. The saturation magnetization for the gram scale synthesized Fe60Co40 alloy nanoparticles is in the range of 190-205 emu/g at room temperature. The as-synthesized nanoparticles were used to fabricate transmission lines on FR4 substrate to perform radio frequency (RF) characterization of the nanoparticles at ISM RF bands of interest (all in GHz range). The complex permeability extraction of composite Fe60Co40 nanoparticles were performed using perturbation technique applied to microstrip transmission lines by relative measurement of full two port scattering parameter with respect to a baseline FR4 substrate. The extracted results show attractive characteristics for small size antennas and filters.
New Measurement of the Anomalous Magnetic Moment of the Positive Muon
Carey, R.M.; Earle, W.; Efstathiadis, E.; Hare, M.F.; Hazen, E.S.; Hughes, B.J.; Krienen, F.; Miller, J.P.; Monich, V.; Ouyang, J.; Rind, O.; Roberts, B.L.; Sulak, L.R.; Trofimov, A.; Varner, G.; Worstell, W.A.; Benedict, E.; Logashenko, I.; Benante, J.; Brown, H.N.; Bunce, G.; Cullen, J.; Danby, G.T.; Geller, J.; Hseuh, H.; Jackson, J.W.; Jia, L.; Kochis, S.; Larsen, R.; Lee, Y.Y.; Mapes, M.; Meng, W.; Morse, W.M.; Pai, C.; Pearson, C.; Polk, I.; Prigl, R.; Rankowitz, S.; Sandberg, J.; Semertzidis, Y.K.; Shutt, R.; Snydstrup, L.; Soukas, A.; Stillman, A.; Tallerico, T.; Tanaka, M.; Toldo, F.; von Lintig, D.; Warburton, D.; Woodle, K.; Logashenko, I.; Chertovskikh, A.; Druzhinin, V.P.; Fedotovich, G.V.; Grigorev, D.N.; Golubev, V.B.; Khazin, B.I.; Maksimov, A.; Merzliakov, Y.; Ryskulov, N.; Serednyakov, S.; Shatunov, Y.M.; Solodov, E.; Orlov, Y.; Winn, D.; Grossmann, A.; Gerhaeuser, J.; Jungmann, K.; von Walter, P.; zu Putlitz, G.; Bunker, B.; Deninger, W.; Debevec, P.T.; Hertzog, D.W.; Jones, T.D.; Polly, C.; Sedykh, S.; Urner, D.; Haeberlen, U.; Endo, K.; Hirabayashi, H.; Kurokawa, S.; Yamamoto, A.; Green, M.A.; Cushman, P.; Kindem, J.; Duong, L.; Giron, S.; and others
1999-02-01
The muon anomalous magnetic moment has been measured in a new experiment at Brookhaven. Polarized muons were stored in a superferric ring, and the angular frequency difference, {omega}{sub a} , between the spin precession and orbital frequencies was determined by measuring the time distribution of high-energy decay positrons. The ratio R of {omega}{sub a} to the Larmor precession frequency of free protons, {omega}{sub p} , in the storage-ring magnetic field was measured. We find R=3.707thinsp220(48){times}10{sup {minus}3} . With {mu}{sub {mu}}/{mu}{sub p}=3.183thinsp 345thinsp47(47) this gives a{sub {mu}{sup +}}=1thinsp165thinsp 925(15){times}10{sup {minus}9} ({plus_minus}13 ppm ), in good agreement with the previous CERN measurements for {mu}{sup +} and {mu}{sup {minus}} and of approximately the same precision. {copyright} {ital 1999} {ital The American Physical Society}
NASA Astrophysics Data System (ADS)
Kulkarni, Anita; Filippone, Bradley; Slutsky, Simon; Swank, Christopher; Carr, Robert; Osthelder, Charles; Biswas, Aritra; Molina, Daniel
2016-09-01
Over the last several decades, physicists have been measuring the neutron electric dipole moment (nEDM) with greater and greater sensitivity. The latest experiment we are developing will have 100 times more sensitivity than the previous leading experiment. A nonzero nEDM could, among other consequences, explain the presence of more matter than antimatter in the universe. To measure the nEDM with high accuracy, it is necessary to have a very uniform magnetic field inside the detector since non-uniformities can create false signals via the geometric phase effect. One way to improve field uniformity is to add superconducting lead endcaps to the detector, which constrain the fields at their surfaces to be parallel to them. Here, we test how the endcaps improve field uniformity by measuring the magnetic field at various points in a 1/3-scale experimental volume, inferring what the field must be at all other points, and calculating gradients in the field. This knowledge could help guide further steps needed to improve field uniformity and characterize limitations to the sensitivity of nEDM measurements for the full-scale experiment. Rose Hills Foundation, National Science Foundation Grant 1506459, and Department of Energy.
Unusual lattice constant changes and tunable magnetic moment compensation in Mn50-xCo25Ga25+x alloys
NASA Astrophysics Data System (ADS)
Li, G. J.; Liu, E. K.; Zhang, H. G.; Qian, J. F.; Zhang, H. W.; Chen, J. L.; Wang, W. H.; Wu, G. H.
2012-09-01
We report on unusual lattice parameter changes and tunable magnetic moment compensation in Mn50-xCo25Ga25+x (x = 0-25) Heusler alloys by substituting Ga for Mn. The observed lattice parameter first increases with increasing Ga content x, showing a maximum at x = 12.5, and then abnormally decreases due to the enhanced covalence effect between transition-metal and main-group atoms. Moreover, a tunable magnetic moment compensation was also observed due to the diversification in role of the main magnetic contributor when the structure varies from Hg2CuTi-type Mn2CoGa to Cu2MnAl-type CoMnGa2. These results provide an alternative way to simultaneously tune both the structural and magnetic properties of Heusler alloys, which is particularly important for developing flexible spintronics devices.
The effect of ions on the magnetic moment of vacancy for ion-implanted 4H-SiC
NASA Astrophysics Data System (ADS)
Peng, B.; Zhang, Y. M.; Dong, L. P.; Wang, Y. T.; Jia, R. X.
2017-04-01
The structural properties and the spin states of vacancies in ion implanted silicon carbide samples are analyzed by experimental measurements along with first-principles calculations. Different types and dosages of ions (N+, O+, and B+) were implanted in the 4H-silicon carbide single crystal. The Raman spectra, positron annihilation spectroscopy, and magnetization-magnetic field curves of the implanted samples were measured. The fitting results of magnetization-magnetic field curves reveal that samples implanted with 1 × 1016 cm-2 N+ and O+ ions generate paramagnetic centers with various spin states of J = 1 and J = 0.7, respectively. While for other implanted specimens, the spin states of the paramagnetic centers remain unchanged compared with the pristine sample. According to the positron annihilation spectroscopy and first-principles calculations, the change in spin states originates from the silicon vacancy carrying a magnetic moment of 3.0 μB in the high dosage N-implanted system and 2.0 μB in the O-doped system. In addition, the ratio of the concentration of implanted N ions and silicon vacancies will affect the magnetic moment of VSi. The formation of carbon vacancy which does not carry a local magnetic moment in B-implanted SiC can explain the invariability in the spin states of the paramagnetic centers. These results will help to understand the magnetic moments of vacancies in ion implanted 4H-SiC and provide a possible routine to induce vacancies with high spin states in SiC for the application in quantum technologies and spintronics.
NASA Astrophysics Data System (ADS)
Bijnens, Johan; Zahiri Abyaneh, Mehran
2012-12-01
We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.
Enhanced effect of C P -violating nuclear magnetic quadrupole moment in a HfF+ molecule
NASA Astrophysics Data System (ADS)
Skripnikov, L. V.; Titov, A. V.; Flambaum, V. V.
2017-02-01
The HfF+ cation is a very promising system to use in the search for the electron electric dipole moment (EDM), and a corresponding experiment is carried out by JILA group [H. Loh, K. C. Cossel, M. C. Grau, K.-K. Ni, E. R. Meyer, J. L. Bohn, J. Ye, and E. A. Cornell, Science 342, 1220 (2013), 10.1126/science.1243683; K.-K. Ni, H. Loh, M. Grau, K. C. Cossel, J. Ye, and E. A. Cornell, J. Mol. Spectrosc. 300, 12 (2014), 10.1016/j.jms.2014.02.001. Here we theoretically investigate the cation to search for another effect which violates time-reversal (T ) and spatial parity (P ) symmetries—the nuclear magnetic quadrupole moment (MQM) interaction with electrons. We report an accurate ab initio relativistic electronic structure calculations of the molecular parameter WM=0.494 10/33Hz e cm2 that is required to interpret the experimental data in terms of the MQM of the Hf nucleus. For this we have implemented and applied the combined Dirac-Coulomb(-Gaunt) and relativistic effective core potential approaches to treat electron correlation effects from all of the electrons and to take into account high-order correlation effects using the coupled cluster method with single, double, triple and noniterative quadruple cluster amplitudes. We discuss interpretation of the MQM effect in terms of the strength constants of T ,P -odd nuclear forces, proton and neutron EDMs, the QCD parameter θ , and quark chromo-EDMs.
Golovko, V. V.; Kraev, I. S.; Phalet, T.; Delaure, B.; Beck, M.; Kozlov, V. Yu.; Coeck, S.; Wauters, F.; Severijns, N.; Herzog, P.; Tramm, Ch.; Zakoucky, D.; Venos, D.; Srnka, D.; Honusek, M.; Koester, U.
2010-05-15
Nuclear magnetic resonance (NMR/ON) measurements with beta- and gamma-ray detection have been performed on oriented {sup 104}Ag{sup g,m} nuclei with the NICOLE {sup 3}He-{sup 4}He dilution refrigerator setup at ISOLDE/CERN. For {sup 104}Ag{sup g} (I{sup p}i=5{sup +}) the gamma-NMR/ON resonance signal was found at nu=266.70(5) MHz. Combining this result with the known magnetic moment for this isotope, the magnetic hyperfine field of Ag impurities in an Fe host at low temperature (<1 K) is found to be |B{sub hf}(AgFe)|=44.709(35) T. A detailed analysis of other relevant data available in the literature yields three more values for this hyperfine field. Averaging all four values yields a new and precise value for the hyperfine field of Ag in Fe; that is, |B{sub hf}(AgFe)|=44.692(30) T. For {sup 104}Ag{sup m} (I{sup p}i=2{sup +}), the anisotropy of the beta particles provided the NMR/ON resonance signal at nu=627.7(4) MHz. Using the new value for the hyperfine field of Ag in Fe, this frequency corresponds to the magnetic moment mu({sup 104m}Ag)=+3.691(3) mu{sub N}, which is significantly more precise than previous results. The magnetic moments of the even-A {sup 102-110}Ag isotopes are discussed in view of the competition between the (pig{sub 9/2}){sub 7/2}{sup +-3}(nud{sub 5/2}nug{sub 7/2}){sub 5/2}{sup +} and the (pig{sub 9/2}){sub 9/2}{sup +-3}(nud{sub 5/2}nug{sub 7/2}){sub 5/2}{sup +} configurations. The magnetic moments of the ground and isomeric states of {sup 104}Ag can be explained by an almost complete mixing of these two configurations.
NASA Astrophysics Data System (ADS)
Scheunert, G.; Ward, C.; Hendren, W. R.; Lapicki, A. A.; Hardeman, R.; Mooney, M.; Gubbins, M.; Bowman, R. M.
2014-10-01
Despite being the most suitable candidates for solenoid pole pieces in state-of-the-art superconductor-based electromagnets, the intrinsic magnetic properties of heavy rare earth metals and their alloys have gained comparatively little attention. With the potential of integration in micro and nanoscale devices, thin films of Gd, Dy, Tb, DyGd and DyTb were plasma-sputtered and investigated for their in-plane magnetic properties, with an emphasis on magnetization versus temperature profiles. Based on crystal structure analysis of the polycrystalline rare earth films, which consist of a low magnetic moment fcc layer at the seed interface topped with a higher moment hcp layer, an experimental protocol is introduced which allows the direct magnetic analysis of the individual layers. In line with the general trend of heavy lanthanides, the saturation magnetization was found to drop with increasing unit cell size. In situ annealed rare earth films exceeded the saturation magnetization of a high-moment Fe65Co35 reference film in the cryogenic temperature regime, proving their potential for pole piece applications; however as-deposited rare earth films were found completely unsuitable. In agreement with theoretical predictions, sufficiently strained crystal phases of Tb and Dy did not exhibit an incommensurate magnetic order, unlike their single-crystal counterparts which have a helical phase. DyGd and DyTb alloys followed the trends of the elemental rare earth metals in terms of crystal structure and magnetic properties. Inter-rare-earth alloys hence present a desirable blend of saturation magnetization and operating temperature.
NASA Astrophysics Data System (ADS)
Krompiewski, S.; Krey, U.; Krauss, U.; Ostermeier, H.
1988-05-01
For realistic structural models of amorphous Fe 1- xB x with 0.2⩽x⩽0.6 and for the fictitious case of x = 0 (amorphous iron, a-Fe), we calculate the distribution function p( ml) of the local magnetic moments ml by means of a self-consistent itinerant electron approach. Generally, p( ml) is rather broad and agrees with experimental hyperfine field distributions. For x→0 and x > 0.5, even negative moments appear, although overlinem remains positive. Additionally we find that for a-Fe a rather drastic transition from paramagnetic behaviour at densities ρ<ρ c(≈8.3 g/cm 3) to ferromagnetism at ρ > ρ c would happen, if the magnetization could be forced to remain homogeneous. However, if the ml are allowed to relax to their local values, no such transition happens. Finally, we study the question whether the spread of the local moments is important for the density of states and find that this is the case except for 0.2⩽x⩽0.35.
NASA Astrophysics Data System (ADS)
Wang, Bochong; Oomiya, Hiroyuki; Arakawa, Akira; Hasegawa, Takashi; Sasaki, Hiromi; Ishio, Shunji
2015-05-01
Tetragonal distorted Fe1-xCox (0 ≤ x ≤ 1) thin films are prepared on L10 ordered Fe0.6Pt0.4 underlayer. The dependences of FeCo alloy composition on magnetic anisotropy energy (MAE) are investigated. Based on the LLG simulation, the tetragonal distorted Fe1-xCox films show maximum positive magnetic anisotropy energy when the Co composition is around 60 at. %, while the MAE decreases and shifts to negative when the composition is close to pure Fe or Co. The experiment results prove that the MAE can be tuned by varying the alloy composition. Furthermore, the magnetic moments of Fe and Co in distorted Fe0.4Co0.6 films are studied by the X-ray magnetic circular dichroism spectroscopy. The enhanced orbit moments which come from the lattice distortion increase the magnetic anisotropy energy of Fe0.4Co0.6 film.
Nuclear magnetic moments of the ground states of sup 124 I, sup 126 I, and sup 130 I
Ohya, S.; Yamazaki, T.; Harasawa, T.; Katsurayama, M.; Mutsuro, N. ); Muto, S.; Heiguchi, K. )
1992-01-01
The nuclear magnetic moments of {sup 124}I, {sup 126}I, and {sup 130}I have been measured by the techniques of low-temperature nuclear orientation and nuclear magnetic resonance on oriented nuclei. The magnetic hyperfine splitting frequency {vert bar}{ital g}{mu}{sub {ital N}BHF}/{ital h}{vert bar} for {sup 124}I{ital Fe} was determined to be 630.2(2) MHz from a field-shift analysis of the measured resonances at the external field of 0.1, 0.2, 0.4, 0.6, and 0.8 T. The resonances for {sup 126}I{ital Fe} and {sup 130}I{ital Fe} were observed in an external magnetic field of 0.2 T at {nu}({sup 126}I{ital Fe})=627.7(2) MHz and {nu}({sup 130}I{ital Fe})=585.7(2) MHz, respectively. Using the recalculated hyperfine field of {ital B}{sub HF}({sup 131}I{ital Fe})=114.50(5) T, the magnetic moments were deduced: {vert bar}{mu}({sup 124}I,2{sup {minus}}){vert bar}=1.444(4){mu}{sub {ital N}}, {vert bar}{mu}({sup 126}I,2{sup {minus}}){vert bar}=1.436(5){mu}{sub {ital N}}, and {vert bar}{mu}({sup 130}I,5{sup +}){vert bar}=3.349(7){mu}{sub {ital N}}. The present value of the magnetic moment of {sup 124}I is very different from the value of 1.14(8){mu}{sub {ital N}} reported previously. The measured values of the magnetic moments are discussed using Lande formula.
NASA Astrophysics Data System (ADS)
Mohanta, S. K.; Mishra, S. N.; Srivastava, S. K.
2014-04-01
We present first principles calculations of electronic structure and magnetic properties of dilute transition metal (3d, 4d and 5d) impurities in a Gd host. The calculations have been performed within the density functional theory using the full potential linearized augmented plane wave technique and the GGA+U method. The spin and orbital contributions to the magnetic moment and the hyperfine fields have been computed. We find large magnetic moments for 3d (Ti-Co), 4d (Nb-Ru) and 5d (Ta-Os) impurities with magnitudes significantly different from the values estimated from earlier mean field calculation [J. Magn. Magn. Mater. 320 (2008) e446-e449]. The exchange interaction between the impurity and host Gd moments is found to be positive for early 3d elements (Sc-V) while in all other cases an anti-ferromagnetic coupling is observed. The trends for the magnetic moment and hyperfine field of d-impurities in Gd show qualitative difference with respect to their behavior in Fe, Co and Ni. The calculated total hyperfine field, in most cases, shows excellent agreement with the experimental results. A detailed analysis of the Fermi contact hyperfine field has been made, revealing striking differences for impurities having less or more than half filled d-shell. The impurity induced perturbations in host moments and the change in the global magnetization of the unit cell have also been computed. The variation within each of the d-series is found to correlate with the d-d hybridization strength between the impurity and host atoms.
Hurd, Wendy J; Kaufman, Kenton R; Murthy, Naveen S
2011-06-01
Medial elbow distraction during pitching as the primary mechanism contributing to adaptations in ulnar collateral ligament (UCL) appearance during magnetic resonance imaging (MRI) evaluation has not been established. Uninjured high school-aged pitchers with unilateral adaptations of the UCL exhibit a higher peak internal elbow adduction moment than those without UCL adaptations. Cohort study (Prevalence); Level of evidence, 2. Twenty uninjured, asymptomatic high school-aged pitchers underwent bilateral elbow MRI examinations. Three-dimensional motion analysis testing was performed to collect throwing arm biomechanics as participants pitched from an indoor mound. Nonparametric tests were performed to compare peak internal elbow adduction moment in uninjured participants with and without adaptations in UCL appearance and to determine the nature of the relationship between the peak internal adduction moment and UCL appearance. Uninjured participants with UCL thickening exhibited a higher peak internal elbow adduction moment of 53.3 ± 6.8 N·m compared with uninjured participants without adaptations in UCL appearance, 38.8 ± 10.9 N·m (P = .05), as higher moments were correlated with ligament thickening (correlation coefficient, 0.45) (P = .02). This study establishes the association between medial elbow distraction captured by the internal adduction moment during pitching and UCL adaptations visible during MRI evaluation.
Hurd, Wendy J.; Kaufman, Kenton R.; Murthy, Naveen S.
2014-01-01
Background Medial elbow distraction during pitching as the primary mechanism contributing to adaptations in ulnar collateral ligament (UCL) appearance during magnetic resonance imaging (MRI) evaluation has not been established. Hypothesis Uninjured high school–aged pitchers with unilateral adaptations of the UCL exhibit a higher peak internal elbow adduction moment than those without UCL adaptations. Study Design Cohort study (Prevalence); Level of evidence, 2. Methods Twenty uninjured, asymptomatic high school–aged pitchers underwent bilateral elbow MRI examinations. Three-dimensional motion analysis testing was performed to collect throwing arm biomechanics as participants pitched from an indoor mound. Nonparametric tests were performed to compare peak internal elbow adduction moment in uninjured participants with and without adaptations in UCL appearance and to determine the nature of the relationship between the peak internal adduction moment and UCL appearance. Results Uninjured participants with UCL thickening exhibited a higher peak internal elbow adduction moment of 53.3 ± 6.8 N·m compared with uninjured participants without adaptations in UCL appearance, 38.8 ± 10.9 N·m (P = .05), as higher moments were correlated with ligament thickening (correlation coefficient, 0.45) (P = .02). Conclusion This study establishes the association between medial elbow distraction captured by the internal adduction moment during pitching and UCL adaptations visible during MRI evaluation. PMID:21335342
Measurement of the anomalous magnetic moment of the negative muon to 0.7 parts per million
NASA Astrophysics Data System (ADS)
Paley, Jonathan M.
The present generation of measurements of the anomalous magnetic moment of the muon (amu) have reached sub part per million (ppm) precision, a level at which they are sensitive to electromagnetic and hadronic interactions, and for the first time, to the electroweak interactions. Comparing the experimental results with Standard Model evaluations provides stringent constraints on physics beyond our current model. The determination of amu at Experiment 821 at Brookhaven National Laboratory requires simultaneous measurements of the muon spin precession frequency and the magnetic field of the muon storage ring. This analysis, one of several to measure the spin precession frequency, uses a ratio of phase-shifted decay electron time spectra to unshifted time spectra. Combined with an independent measurement of the magnetic field, the anomalous magnetic moment of the negative muon has now been determined to a precision of 0.7 parts per million (ppm): amu- = 11659214(8)(3) x 10-10. This value is in good agreement with measurements of the anomalous magnetic moment of the positive muon: amu+ = 11659204(7)(5) x 10-10 (0.7 ppm). We discuss the principle of and the analysis techniques used in this experiment, and compare the final results with the theoretical prediction for amu.
NASA Astrophysics Data System (ADS)
Hou, Y. S.; Xiang, H. J.; Gong, X. G.
2017-08-01
Recent experiments reveal that the honeycomb ruthenium trichloride α -RuC l3 is a prime candidate of the Kitaev quantum spin liquid (QSL). However, there is no theoretical model which can properly describe its experimental dynamical response due to the lack of a full understanding of its magnetic interactions. Here, we propose a general scheme to calculate the magnetic interactions in systems (e.g., α -RuC l3 ) with nonnegligible orbital moments by constraining the directions of orbital moments. With this scheme, we put forward a minimal J1-K1-Γ1-J3-K3 model for α -RuC l3 and find that: (I) The third nearest neighbor (NN) antiferromagnetic Heisenberg interaction J3 stabilizes the zigzag antiferromagnetic order; (II) The NN symmetric off-diagonal exchange Γ1 plays a pivotal role in determining the preferred direction of magnetic moments and generating the spin wave gap. An exact diagonalization study on this model shows that the Kitaev QSL can be realized by suppressing the NN symmetric off-diagonal exchange Γ1 and the third NN Heisenberg interaction J3. Thus, we not only propose a powerful general scheme for investigating the intriguing magnetism of Jeff=1 /2 magnets, but also point out future directions for realizing the Kitaev QSL in the honeycomb ruthenium trichloride α -RuC l3 .
Jamer, Michelle E.; Sterbinsky, George E.; Stephen, Gregory M.; ...
2016-10-31
Recently, theorists have predicted many materials with a low magnetic moment and large spin-polarization for spintronic applications. These compounds are predicted to form in the inverse Heusler structure; however, many of these compounds have been found to phase segregate. In this study, ordered Cr2CoGa thin films were synthesized without phase segregation using molecular beam epitaxy. The present as-grown films exhibit a low magnetic moment from antiferromagnetically coupled Cr and Co atoms as measured with superconducting quantum interface device magnetometry and soft X-ray magnetic circular dichroism. Electrical measurements demonstrated a thermally-activated semiconductor-like resistivity component with an activation energy of 87 meV.more » These results confirm spin gapless semiconducting behavior, which makes these thin films well positioned for future devices.« less
Ito, Keita; Sanai, Tatsunori; Yasutomi, Yoko; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi; Zhu, Siyuan; Kimura, Akio; Ueda, Shigenori; Takeda, Yukiharu; Saitoh, Yuji; Imai, Yoji
2013-12-02
We evaluated electronic structures and magnetic moments in Co{sub 3}FeN epitaxial films on SrTiO{sub 3}(001). The experimentally obtained hard x-ray photoemission spectra of the Co{sub 3}FeN film have a good agreement with those calculated. Site averaged spin magnetic moments deduced by x-ray magnetic circular dichroism were 1.52 μ{sub B} per Co atom and 2.08 μ{sub B} per Fe atom at 100 K. They are close to those of Co{sub 4}N and Fe{sub 4}N, respectively, implying that the Co and Fe atoms randomly occupy the corner and face-centered sites in the Co{sub 3}FeN unit cell.
Das, Chinmoy; Vaidya, Shefali; Gupta, Tulika; Frost, Jamie M; Righi, Mattia; Brechin, Euan K; Affronte, Marco; Rajaraman, Gopalan; Shanmugam, Maheswaran
2015-10-26
Three cationic [Ln4 ] squares (Ln=lanthanide) were isolated as single crystals and their structures solved as [Dy4 (μ4 -OH)(HL)(H2 L)3 (H2 O)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)8 (1), [Tb4 (μ4 -OH)(HL)(H2 L)3 (MeOH)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)4 (2) and [Gd4 (μ4 -OH)(HL)(H2 L)3 (H2 O)2 (MeOH)2 ]Br2 ⋅(CH3 OH)4 ⋅(H2 O)3 (3). The structures are described as hydroxo-centered squares of lanthanide ions, with each edge of the square bridged by a doubly deprotonated H2 L(2-) ligand. Alternating current magnetic susceptibility measurements show frequency-dependent out-of-phase signals with two different thermally assisted relaxation processes for 1, whereas no maxima in χM " appears above 2.0 K for complex 2. For 1, the estimated effective energy barrier for these two relaxation processes is 29 and 100 K. Detailed ab initio studies reveal that complex 1 possesses a toroidal magnetic moment. The ab initio calculated anisotropies of the metal ions in complex 1 were employed to simulate the magnetic susceptibility by using the Lines model (POLY_ANISO) and this procedure yields J1 =+0.01 and J2 =-0.01 cm(-1) for 1 as the two distinct exchange interactions between the Dy(III) ions. Similar parameters are also obtained for complex 1 (and 2) from specific heat measurements. A very weak antiferromagnetic super-exchange interaction (J1 =-0.043 cm(-1) and g=1.99) is observed between the metal centers in 3. The magnetocaloric effect (MCE) was estimated by using field-dependent magnetization and temperature-dependent heat-capacity measurements. An excellent agreement is found for the -ΔSm values extracted from these two measurements for all three complexes. As expected, 3 shows the largest -ΔSm variation (23 J Kg(-1) K(-1) ) among the three complexes. The negligible magnetic anisotropy of Gd indeed ensures near degeneracy in the (2S+1) ground state microstates, and the weak super-exchange interaction facilitates dense population of low-lying excited states, all of
NASA Astrophysics Data System (ADS)
Araujo, Jonas B.; Casana, Rodolfo; Ferreira, Manoel M.
2015-07-01
We analyze some dimension-five C P T -even and Lorentz-violating nonminimal couplings between fermionic and gauge fields in the context of the Dirac equation. After evaluating the nonrelativistic Hamiltonian, we discuss the behavior of the terms under discrete symmetries and analyze the implied effects. We then use the anomalous magnetic dipole moment and electron electric dipole moment measurements to reach upper bounds of 1 part in 1020 and 1024 (eV )-1 , improving the level of restriction on such couplings by at least 8 orders of magnitude. These upper bounds are also transferred to the Sun-centered frame by considering the Earth's rotational motion.
A new software for the measurement of magnetic moments using a SQUID magnetometer
NASA Astrophysics Data System (ADS)
Wack, M.
2009-12-01
A new software package called CryoMag to carry out measurements of magnetic moments is presented. It is designed to work with SQUID magnetometers manufactured by 2G Enterprises, but the modular design allows easy adaption to other instruments like spinner magnetometers as well. The measurement process is optimized for, but not limited to, stepwise demagnetization experiments commonly used in paleomagnetism. A graphical representation of the data is always visible to the user in the form of orthogonal, stereographic and decay plots, which can be represented in in-situ, geographic or tilt corrected coordinates and can be saved to graphics files. Measurement positions can be easily customized. A comprehensive record of detailed measurement and statistical data is stored in XML (eXtensible Markup Language) based data files (*.cmag.xml). The final results of the measurements can be exported to various common file formats for further processing. The software is written in Python, an open source, cross-platform programming language and can therefore be used on all major operating systems like Windows, Linux and MacOS X (not tested).
A new software for the measurement of magnetic moments using SQUID and spinner magnetometers
NASA Astrophysics Data System (ADS)
Wack, M.
2010-09-01
A new software package, called CryoMag, facilitates the measurement of magnetic moments using both 3-component (i.e. Superconducting QUantum Interference Device) and 2-component (i.e. spinner) magnetometers. The measurement process is optimized for, but not limited to, stepwise demagnetization experiments commonly used in paleomagnetism. A graphical representation of the data is always visible to the user in the form of orthogonal, stereonet and decay diagrams, which can be represented in in situ, geographic or tilt corrected coordinates and can be saved as graphics files. Instrument specific settings, as well as arbitrary measurement positions, can be easily customized in a single configuration file. A comprehensive record of detailed measurement and statistical data is stored in XML (eXtensible Markup Language) based data files (*.cmag.xml). The final results of the measurements can be exported to several common file formats for further processing. The software is written in Python, an open source, cross-platform programming language and can therefore be used on popular operating systems like Windows, Linux and MacOS X. The complete source code is available on request from the author. The CryoMag open-source allows anyone to adapt the software to their specific equipment, file format and experimental requirements.
Final report of the E821 muon anomalous magnetic moment measurement at BNL
Bennett, G.W.; Brown, H.N.; Bunce, G.; Danby, G.T.; Larsen, R.; Lee, Y.Y.; Meng, W.; Mi, J.; Morse, W.M.; Nikas, D.; Prigl, R.; Semertzidis, Y.K.; Warburton, D.; Bousquet, B.; Cushman, P.; Duong, L.; Giron, S.; Kindem, J.; Kronkvist, I.; Qian, T.
2006-04-01
We present the final report from a series of precision measurements of the muon anomalous magnetic moment, a{sub {mu}}=(g-2)/2. The details of the experimental method, apparatus, data taking, and analysis are summarized. Data obtained at Brookhaven National Laboratory, using nearly equal samples of positive and negative muons, were used to deduce a{sub {mu}}(Expt)=11659208.0(5.4)(3.3)x10{sup -10}, where the statistical and systematic uncertainties are given, respectively. The combined uncertainty of 0.54 ppm represents a 14-fold improvement compared to previous measurements at CERN. The standard model value for a{sub {mu}} includes contributions from virtual QED, weak, and hadronic processes. While the QED processes account for most of the anomaly, the largest theoretical uncertainty, {approx_equal}0.55 ppm, is associated with first-order hadronic vacuum polarization. Present standard model evaluations, based on e{sup +}e{sup -} hadronic cross sections, lie 2.2-2.7 standard deviations below the experimental result.
Higgs mass and muon anomalous magnetic moment in the MSSM with gauge-gravity hybrid mediation
NASA Astrophysics Data System (ADS)
Zhu, Bin; Ding, Ran; Li, Tianjun
2017-08-01
In general, we can propose the hybrid supersymmetry breakings and hybrid mediations in the supersymmetric standard models. In this paper, we study the hybrid mediation for supersymmetry (SUSY) breaking. In particular, we study how to keep the good properties of gravity mediation, gauge mediation, and anomaly mediation, while solving their problems simultaneously. As an example, we consider the gauge-gravity mediation, where all the supersymmetric particles (sparticles) obtain the SUSY breaking soft terms from the traditional gravity mediation while gauge mediation gives dominant contributions to the soft terms in the colored sector due to the splitted messengers. Thus, we can realize the electroweak supersymmetry naturally where the sleptons, sneutrinos, and electroweakinos are light within one TeV while the squarks and gluino are heavy around a few TeVs. Then we can explain 125 GeV Higgs mass, satisfy the LHC SUSY search bounds, and explain the anomalous magnetic moment of muon, etc. Moreover, the gluino and squarks are well beyond the current LHC run II searches.
Average magnetic moments of pre-yrast high spin states in {sup 166,165}Hf
Weissman, L.; Hass, M.; Broude, C.
1996-01-01
The average magnetic moments of high spin states in Hf isotopes were determined in a transient field measurement at the 14 MV Koffler accelerator of the Weizmann Institute. The reaction {sup 130}Te({sup 40}Ca,{ital xn}){sup 166,165}Hf at beam energies from 167 to 182.5 MeV was used to populate different high spin regions and provide the recoiling Hf nuclei with sufficient velocity to traverse the 2.9 mg/cm{sup 2} Gd ferromagnetic layer. Standard double ratios and angular distributions for various low level transitions were measured to determine precession angles. These carry information regarding the average {ital g} factor of unobservable transitions at medium excitation. To obtain a more quantitative analysis regarding the time-decay history of the {gamma} cascade, Monte Carlo simulations of the cascade were carried out. The significance of the results for understanding the single particle nature of these pre-yrast levels is discussed. {copyright} {ital 1996 The American Physical Society.}
Superexchange interaction and magnetic moment in antiferromagnetic high-T cuprate superconductors
NASA Astrophysics Data System (ADS)
Mukuda, Hidekazu; Shimizu, Sunao; Tabata, Shin-Ichiro; Itohara, Keita; Kitaoka, Yoshio; Shirage, Parasharam M.; Iyo, Akira
2010-12-01
We report a 63Cu-NMR study on underdoped Hg-based five-layered (n = 5) compounds HgBa2Ca4Cu5O12+y (Hg-1245) with T=82K and 92 K, and review the previous Cu-NMR results on the various multilayered cuprates. On the basis of extensive experiments on n=5 compounds, we have unraveled that (1) the antiferromagnetic metallic (AFMM) phase is robust up to the carrier-density Nh˜0.17, (2) the uniformly mixed state of superconductivity (SC) and AFMM is realized at least in 0.14
Macroscopic kinematics of the Hall electric field under influence of carrier magnetic moments
Sakai, Masamichi
2016-06-15
The relativistic effect on electromagnetic forces yields two types of forces which depend on the velocity of the relevant particles: (i) the usual Lorentz force exerted on a moving charged particle and (ii) the apparent Lorentz force exerted on a moving magnetic moment. In sharp contrast with type (i), the type (ii) force originates due to the transverse field induced by the Hall effect (HE). This study incorporates both forces into a Drude-type equation with a fully spin-polarized condition to investigate the effects of self-consistency of the source and the resultant fields on the HE. We also examine the self-consistency of the carrier kinematics and electromagnetic dynamics by simultaneously considering the Drude type equation and Maxwell equations at low frequencies. Thus, our approach can predict both the dc and ac characteristics of the HE, demonstrating that the dc current condition solely yields the ordinary HE, while the ac current condition yields generation of both fundamental and second harmonic modes of the HE field. When the magnetostatic field is absent, the simultaneous presence of dc and ac longitudinal currents generates the ac HE that has both fundamental frequency and second harmonic.
Nuclear structure of the even-even argon isotopes with a focus on magnetic moments
Robinson, S. J. Q.; Sharon, Y. Y.; Zamick, L.
2009-05-15
We study the role of configuration mixing in the heavier even-even isotopes of argon. We begin by limiting the configurations of the even-even Ar isotopes to (d{sub 3/2}{sup 2}){sub {pi}} (f{sub 7/2}{sup n}){sub {nu}}. There, due to the particular location in this shell-model space of {sup 40}Ar and {sup 44}Ar, we find that the spectra, B(E2)'s, and magnetic moments of these two nuclei are identical. Any deviation from this equality is direct evidence of configuration mixing. In a larger shell-model space there are significant differences between these two nuclei, with {sup 44}Ar being more collective. We also consider other even-even isotopes of argon and study how their nuclear structure effects evolve with N. We compare in the full 0({Dirac_h}/2{pi}) {omega} space (sd){sub {pi}} (fp){sub {nu}} the results of calculations with the WBT interaction and with the newer SDPF, denoted SDPF-U, interaction.
Magnetic Moments of the 21+ and 41+ States in 110SN
NASA Astrophysics Data System (ADS)
Kumbartzki, Gerfried; Benczer-Koller, N.; Bernstein, L.; Torres, D. A.; Speidel, K.-H.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bevins, J. M.; Hurst, A.; Guevara, Z. E.; Gürdal, G.; Kirsch, L.; Laplace, T.; Lo, A.; Crawford, H. L.; Matthew, E.; Meyers, I.; Phair, L.; Ramirez, F.; Sharon, Y. Y.; Wiens, A.
2015-10-01
The structure of the Sn isotopes has been studied via measurements of B(E2;21+->01+) transition rates and g factors of 21+ states. Values of B(E2)'s in the lighter isotopes show an increase in collectivity below midshell, contrary to predictions from shell model calculations. In order to better establish the structure of these neutron-deficient isotopes, measurements of g factors in 110Sn, where the neutrons might occupy both the g7/2 and d5/2 orbitals, have been carried out. The states of interest were populated in the reaction 12C(106Cd, 2 α)110Sn, at the LBNL 88 inch cyclotron. The γ rays were detected in ORNL and LBNL clover detectors. The transient field technique was used to obtain magnetic moments. The details of the experiment and the results will be presented. The authors acknowledge support from the US NSF and DoE, the Colombia Colciencias and the German DFG.
Terrestrial and Reactor Antineutrinos in Borexino
NASA Astrophysics Data System (ADS)
Chen, M. C.; Calaprice, F. P.; Rothschild, C. G.
1998-10-01
The Earth is an abundant source of antineutrinos coming from the decay of radioactive elements in the mantle and crust. Detecting these antineutrinos is a challenge due to their small cross section and low energies. The Borexino solar neutrino experiment will also be an excellent detector for barν_e. With 300 tons of ultra-low-background liquid scintillator, surrounded by an efficient muon veto, the inverse-β-decay reaction: barνe + p arrow e^+ + n (Q = 1.8 MeV), can be exploited to detect terrestrial antineutrinos from the uranium and thorium decay chains, with little background. A direct measurement of the total uranium and thorium abundance would establish important geophysical constraints on the heat generation and thermal history of the Earth. Starting with the most recent uranium and thorium distribution and abundance data, and employing a global map of crustal type and thickness, we calculated the antineutrino fluxes for several sites. We estimate a terrestrial antineutrino event rate in Borexino of 10 events per year. This small signal can be distinguished over the neutrino background from the world's nuclear power reactors by measuring the positron energy spectrum from the barνe events. The possibility to perform a long-baseline oscillation experiment, reaching Δ m^2 ≈ 10-6 eV^2, using the nuclear reactors in Europe will also be discussed.
A Direction-Sensitive Detector for Electron Antineutrinos
Brooks, F. D.; Drosg, M.; Smit, F. D.
2011-12-13
A modular design is proposed for an electron antineutrino detector based on boron-doped liquid scintillator. Tests have been carried out on small detector systems using neutrons to simulate the antineutrino detection signature. Results from these tests are reported, and the possibility of using a larger system of similar design to detect reactor antineutrinos is discussed.
Meinert, M.; Schmalhorst, J; Klewe, C.; Reiss, G.; Arenholz, E.; Bohnert, T.; Nielsch, K.
2011-08-08
Epitaxial thin films of the half-metallic X{sub a}-compound Mn{sub 2}CoGa (Hg{sub 2}CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality lms with a bulk magnetization of 1.95(5) {mu}{sub }B per unit cell were obtained. The average Mn magnetic moment and the Co moment are parallel, in agreement with theory. The x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism allows to distinguish between itinerant and localized Mn moments. It is shown that one of the two Mn moments has localized character, whereas the other Mn moment and the Co moment are itinerant.
Sun, X.; Wang, B.; Pratt, A.; Yamauchi, Y.
2014-07-21
The geometric, electronic, and magnetic structures of a manganese phthalocyanine (MnPc) molecule on an antiferromagnetic IrMn(100) surface are studied by density functional theory calculations. Two kinds of orientation of the adsorbed MnPc molecule are predicted to coexist due to molecular self-assembly on the surface—a top-site geometry with the Mn–N bonds aligned along the 〈100〉 direction, and a hollow-site orientation in which the Mn–N bonds are parallel to the 〈110〉 direction. The MnPc molecule is antiferromagnetically coupled to the substrate at the top site with a slight reduction in the magnetic moment of the Mn atom of the MnPc molecule (Mn{sub mol}). In contrast, the magnetic moment of the Mn{sub mol} is enhanced to 4.28 μB at the hollow site, a value larger than that in the free MnPc molecule (3.51 μB). Molecular distortion induced by adsorption is revealed to be responsible for the enhancement of the magnetic moment. Furthermore, the spin polarization of the Mn{sub mol} atom at around the Fermi level is found to change from negative to positive through an elongation of the Mn–N bonds of the MnPc. We propose that a reversible switch of the low/high magnetic moment and negative/positive spin polarization might be realized through some mechanical engineering methods.
NASA Astrophysics Data System (ADS)
Takahashi, Y.; Kadono, T.; Yamamoto, S.; Singh, V. R.; Verma, V. K.; Ishigami, K.; Shibata, G.; Harano, T.; Takeda, Y.; Okane, T.; Saitoh, Y.; Yamagami, H.; Takano, M.; Fujimori, A.
2014-07-01
We have investigated the spin and orbital magnetic moments of Fe in FePt nanoparticles in the L10-ordered phase coated with SiO2 by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe L2,3 absorption edges. Using XMCD sum rules, we evaluated the ratio of the orbital magnetic moment (Morb) to the effective spin magnetic moment (Mspineff) of Fe to be Morb/Mspineff=0.08. This Morb/Mspineff value is comparable to the value (0.09) obtained for FePt nanoparticles prepared by gas phase condensation, and is larger than the values (˜0.05) obtained for FePt thin films, indicating a high degree of L10 order. The hysteretic behavior of the FePt component of the magnetization was measured by XMCD. The magnetic coercivity (Hc) was found to be as large as 1.8 T at room temperature, ˜3 times larger than the thin film value and ˜50 times larger than that of the gas phase condensed nanoparticles. The hysteresis curve is well explained by the Stoner-Wohlfarth model for noninteracting single-domain nanoparticles with the Hc distributed from 1 to 5 T.
In-gas-cell laser spectroscopy of the magnetic dipole moment of the N ≈126 isotope 199Pt
NASA Astrophysics Data System (ADS)
Hirayama, Y.; Mukai, M.; Watanabe, Y. X.; Ahmed, M.; Jeong, S. C.; Jung, H. S.; Kakiguchi, Y.; Kanaya, S.; Kimura, S.; Moon, J. Y.; Nakatsukasa, T.; Oyaizu, M.; Park, J. H.; Schury, P.; Taniguchi, A.; Wada, M.; Washiyama, K.; Watanabe, H.; Miyatake, H.
2017-07-01
The magnetic dipole moment and mean-square charge radius of Ptg199 (Iπ= 5 /2-,t1 /2= 30.8 min) ground state and Ptm199 (Eex= 424 keV, Iπ= (13/2)+,t1 /2= 13.6 s) isomeric state are evaluated for the first time from investigations of the hyperfine splitting of the λ1= 248.792 nm transition by in-gas-cell laser ionization spectroscopy. Ground and isomeric states of neutron-rich 199Pt nucleus were produced by a multinucleon transfer reaction at the KEK Isotope Separation System (KISS), designed for the study of nuclear spectroscopy in the vicinity of N = 126 . The measured magnetic dipole moments +0.75 (8)μN and -0.57 (5)μN are consistent with the systematics of those of nuclei with Iπ= 5 /2- and Iπ= 13 /2+ , respectively.
Magnetic moment and lifetime measurements of Coulomb-excited states in Cd106
Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K. -H.; ...
2016-09-06
The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. As a result, the g factorsmore » of the 2+1 and 4+1 states in 106Cd were measured to be g(2+1) = +0.398(22) and g(4+1) = +0.23(5). A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ(106Cd; 2+1) = 7.0(3) ps and τ(106Cd; 4+1) = 2.5(2) ps. The mean life τ(106Cd; 2+2) = 0.28(2) ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ(106Cd; 4+3) = 1.1(1) ps and τ(106Cd; 3–1) = 0.16(1) ps were determined for the first time. In conclusion, the newly measured g(4+1) of 106Cd is found to be only 59% of the g(2+1). This difference cannot be explained by either shell-model or collective-model calculations.« less
Magnetic moment and lifetime measurements of Coulomb-excited states in 106Cd
NASA Astrophysics Data System (ADS)
Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K.-H.; Torres, D. A.; Robinson, S. J. Q.; Sharon, Y. Y.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Wiens, A.
2016-09-01
Background: The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Purpose: Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. Results: The g factors of the 21+ and 41+ states in 106Cd were measured to be g (21+)=+0.398 (22 ) and g (41+)=+0.23 (5 ) . A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ (106Cd;21+)=7.0 (3 )ps and τ (106Cd;41+)=2.5 (2 )ps . The mean life τ (106Cd;22+)=0.28 (2 )ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ (106Cd;43+)=1.1 (1 )ps and τ (106Cd;31-)=0.16 (1 )ps were determined for the first time. Conclusions: The newly measured g (41+) of 106Cd is found to be only 59% of the g (21+) . This difference cannot be explained by either shell-model or collective-model calculations.
Z =50 core stability in 110Sn from magnetic-moment and lifetime measurements
NASA Astrophysics Data System (ADS)
Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K.-H.; Torres, D. A.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Gürdal, G.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Robinson, S. J. Q.; Sharon, Y. Y.; Wiens, A.
2016-04-01
Background: The structure of the semimagic 50Sn isotopes were previously studied via measurements of B (E 2 ;21+→01+ ) and g factors of 21+ states. The values of the B (E 2 ;21+ ) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. Purpose: This work presents the first measurement of the 2 1+ and 4 1+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B (E 2 ) values. Methods: The 110Sn nuclei have been produced in inverse kinematics in an α -particle transfer reaction from 12C to 106Cd projectiles at 390, 400, and 410 MeV. The g factors have been measured with the transient field technique. Lifetimes have been determined from line shapes using the Doppler-shift attenuation method. Results: The g factors of the 21+ and 41+ states in 110Sn are g (21+) = +0.29(11) and g (41+) = +0.05(14), respectively. In addition, the g (41+) = +0.27(6) in 106Cd has been measured for the first time. A line-shape analysis yielded τ (110Sn ; 21+) = 0.81(10) ps and a lifetime of τ (110Sn ; 31-) = 0.25(5) ps was calculated from the fully Doppler-shifted γ line. Conclusions: No evidence has been found in 110Sn that would require excitation of protons from the closed Z =50 core.
Implications of the Muon Anomalous Magnetic Moment for Direct Detection of Neutralino Dark Matter
NASA Astrophysics Data System (ADS)
Kim, Y. G.; Nojiri, M. M.
2001-09-01
We investigate the implications of a recent measurement of the muon anomalous magnetic moment for the direct detection of neutralino dark matter in three different SUSY models: mSUGRA, a model with non-universal Higgs mass, and an SO(10) GUT model. We consider two cases for the value of Δ aμ, 27 × 10-10 < Δ aμ < 59 × 10-10 (corresponding to a range of 1σ about the experimental value) and 0 < Δ aμ < 11 × 10-10 (corresponding to a range more than 2σ below the experimental value). In the mSUGRA model, the counting ratio may be above the sensitivity of future experiments in the case that parameters are within a 1σ bound of Δ aμ. However, Ωχ tends to be large compared to the currently accepted value Ω=0.3. For models with non-universal scalar masses, the possibility of having a consistent Ωχ and a large counting ratio exists in the region of parameter space where the Higgsino mass μ is smaller than the mSUGRA prediction. In particular, in the SO(10) model, the LSP dark matter detection rate may be enhanced by almost one order of magnitude compared to that in mSUGRA and the model with non-universal Higgs mass, for cosmologically acceptable Ωχ h2. The highest detection rate of LSP dark matter occurs in the region where the LSP constitutes a subdominant part of the local halo DM. The implications of the SUSY mass parameter measurement subject to the cosmological constraint are also discussed.
Magnetic moment for the negative parity Λ → Σ0 transition in light cone QCD sum rules
NASA Astrophysics Data System (ADS)
Aliev, T. M.; Savcı, M.
2016-07-01
The magnetic moment of the Λ →Σ0 transition between negative parity baryons is calculated in framework of the QCD sum rules approach by using the general form of the interpolating currents. The pollution arising from the positive-to-positive, and positive-to-negative parity baryons is eliminated by constructing the sum rules for different Lorentz structures. A comparison of our result with the predictions of the results of other approaches for the positive parity baryons is presented.
Hambye, Thomas; Kannike, Kristjan; Raidal, Martti; Ma, Ernest
2007-05-01
The evidence for dark matter signals a new class of particles at the TeV scale, which may manifest themselves indirectly through loop effects. In a simple model we show that these loop effects may be responsible for the enhanced muon anomalous magnetic moment, for the neutrino mass, as well as for leptogenesis in a novel way. This scenario can be verified at LHC and/or ILC experiments.
Wurmehl, Sabine; Fecher, Gerhard H.; Kandpal, Hem C.; Ksenofontov, Vadim; Felser, Claudia; Lin Hongji; Morais, Jonder
2005-11-01
In this work a simple concept was used for a systematic search for materials with high spin polarization. It is based on two semiempirical models. First, the Slater-Pauling rule was used for estimation of the magnetic moment. This model is well supported by electronic structure calculations. The second model was found particularly for Co{sub 2} based Heusler compounds when comparing their magnetic properties. It turned out that these compounds exhibit seemingly a linear dependence of the Curie temperature as function of the magnetic moment. Stimulated by these models, Co{sub 2}FeSi was revisited. The compound was investigated in detail concerning its geometrical and magnetic structure by means of x-ray diffraction, x-ray absorption, and Moessbauer spectroscopies as well as high and low temperature magnetometry. The measurements revealed that it is, currently, the material with the highest magnetic moment (6{mu}{sub B}) and Curie temperature (1100 K) in the classes of Heusler compounds as well as half-metallic ferromagnets. The experimental findings are supported by detailed electronic structure calculations.
Magnetic dipole moments of {sup 58}Cu and {sup 59}Cu by in-source laser spectroscopy
Stone, N. J.; Koester, U.; Stone, J. Rikovska; Fedorov, D. V.; Fedoseyev, V. N.; Flanagan, K. T.; Hass, M.; Lakshmi, S.
2008-06-15
Online measurements of the magnetic dipole moments and isotope shifts of {sup 58}Cu and {sup 59}Cu by the in-source laser spectroscopy method are reported. The results for the magnetic moments are {mu} ({sup 58}Cu) =+0.52(8) {mu}{sub N},{mu}({sup 59}Cu) =+1.84(3) {mu}{sub N} and for the isotope shifts {delta}{nu}{sup 59,65}=1.72(22) GHz and {delta}{nu}{sup 58,65}=1.99(30) GHz in the transition from the 3d{sup 10}4s {sup 2}S{sub 1/2} ground state to the 3d{sup 10}4p {sup 2}P{sub 1/2} state in Cu I. The magnetic moment of {sup 58}Cu is discussed in the context of the strength of the subshell closure at {sup 56}Ni, additivity rules and large-scale shell model calculations.
NASA Technical Reports Server (NTRS)
Slavin, J. A.; Holzer, R. E.
1979-01-01
The determination of Mercury's magnetic moment from the spatially and temporally limited observations obtained by the Mariner 10 mission is dependent upon the assumed nature of both the intrinsic planetary magnetic field and that of the magnetospheric current systems. In this paper the methods that have been used for this purpose are reviewed. The results that have been obtained are then considered in comparison with the constraints placed on the planetary field by the solar wind dynamic pressures and stand-off distances inferred from the Mariner 10 magnetic field data by Slavin and Holtzer (1979) which are consistent with an effective dipole moment of 6 + or - 2 x 10 to the 22nd G cu cm. It is found that the models which fit the observations with substantial quadrupole and octupole moments are not consistent with the magnetospheric boundary conditions, presumably owing to incorrect assumptions regarding the magnetopause position, incorrect assumptions regarding solar wind dynamic pressure, and/or averaging over temporal variations in the Mariner 10 data.
NASA Astrophysics Data System (ADS)
Silenko, Alexander J.
2017-05-01
A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantum-mechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. The main systematical errors are considered.
NASA Astrophysics Data System (ADS)
Barzakh, A. E.; Andreyev, A. N.; Cocolios, T. E.; de Groote, R. P.; Fedorov, D. V.; Fedosseev, V. N.; Ferrer, R.; Fink, D. A.; Ghys, L.; Huyse, M.; Köster, U.; Lane, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Molkanov, P. L.; Procter, T. J.; Rapisarda, E.; Rothe, S.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van Beveren, C.; Van Duppen, P.; Venhart, M.; Veselský, M.
2017-01-01
Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron-deficient isotopes Tl-184179 using the 276.9-nm transition. The experiment has been performed at the CERN-Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in 179,181,183Tl have been determined as I =1 /2 . Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in Tl,184182 from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes Tl-184179 follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of Tl,184183 has been observed, suggesting a larger deformation for the intruder-based 9 /2- and 10- states compared to the ground states. An unexpected growth of the isomer shift for 183Tl has been found.
Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4
Krupin, O.; Dakovski, G. L.; Kim, B. J.; ...
2016-06-16
Here, we report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by themore » $${{J}_{\\text{eff}}}=1/2$$ states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump–hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps–1.5 ns.« less
Muñoz-Jaramillo, Andrés; Balmaceda, Laura A; DeLuca, Edward E
2013-07-26
The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and Earth's upper atmosphere (commonly referred to as space weather and climate). In recent years there has been an effort to develop accurate solar cycle predictions, leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. Here we show that cycle predictions can be made more accurate if performed separately for each hemisphere, taking advantage of information about both the dipolar and quadrupolar moments of the solar magnetic field during minimum.
Ferromagnetism at room temperature with a large magnetic moment in anatase V-doped TiO2 thin films
NASA Astrophysics Data System (ADS)
Hong, Nguyen Hoa; Sakai, Joe; Hassini, Awatef
2004-04-01
V-doped TiO2 thin films were grown by laser ablation on LaAlO3 substrates. In the chosen range of the growth conditions, all V:TiO2 films have an anatase structure and exhibit semiconducting and ferromagnetic behaviors at room temperature. V:TiO2 films have a giant magnetic moment and they seem to be far better ferromagnetic than Co/Fe/Ni-doped TiO2 films. This study has proved that a few percent of V substituting for Ti in TiO2 can result in a potential diluted magnetic semiconductor.
Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4
NASA Astrophysics Data System (ADS)
Krupin, O.; Dakovski, G. L.; Kim, B. J.; Kim, J. W.; Kim, Jungho; Mishra, S.; Chuang, Yi-De; Serrao, C. R.; Lee, W.-S.; Schlotter, W. F.; Minitti, M. P.; Zhu, D.; Fritz, D.; Chollet, M.; Ramesh, R.; Molodtsov, S. L.; Turner, J. J.
2016-08-01
We report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by the {{J}\\text{eff}}=1/2 states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump-hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps-1.5 ns.
High temperature ferromagnetism with a giant magnetic moment in transparent co-doped SnO(2-delta).
Ogale, S B; Choudhary, R J; Buban, J P; Lofland, S E; Shinde, S R; Kale, S N; Kulkarni, V N; Higgins, J; Lanci, C; Simpson, J R; Browning, N D; Das Sarma, S; Drew, H D; Greene, R L; Venkatesan, T
2003-08-15
The occurrence of room temperature ferromagnetism is demonstrated in pulsed laser deposited thin films of Sn(1-x)Co(x)O(2-delta) (x<0.3). Interestingly, films of Sn(0.95)Co(0.05)O(2-delta) grown on R-plane sapphire not only exhibit ferromagnetism with a Curie temperature close to 650 K, but also a giant magnetic moment of 7.5+/-0.5 micro(B)/Co, not yet reported in any diluted magnetic semiconductor system. The films are semiconducting and optically highly transparent.
NASA Astrophysics Data System (ADS)
Vincent, John B.
1999-10-01
Most freshman chemistry textbooks include a figure illustrating the relationship between spinning electrons and the resultant magnetic field. However, some textbooks predict the direction of the magnetic moment using the left-hand rule, while others incorrectly use the right-hand rule. An examination of textbooks published during the last four decades reveals that reversal of the direction of the resultant magnetic field accompanied the introduction of these figures into freshman chemistry textbooks about 20 years ago. Since then, these illustrations have become increasingly popular; and while the error persists, its rate of occurrence has declined until most current textbooks have the direction of the magnetic field produced by a spinning electron correct.
Ultrathin magnetite in Fe3O4/MgO superlattices: Investigating the enhanced thin film magnetic moment
NASA Astrophysics Data System (ADS)
Mauit, Ozhet; Fleischer, Karsten; O'Coileáin, Cormac; Bulfin, Brendan; Fox, Daniel S.; Smith, Christopher M.; Mullarkey, Daragh; Sugurbekova, Gulnar; Zhang, Hongzhou; Shvets, Igor V.
2017-03-01
The electrical, crystallographic, and magnetic properties of ultrathin magnetite (Fe3O4 ) have been studied in detail, by employing superlattice structures of Fe3O4 /MgFe2O4 and Fe3O4 /MgO on a variety of substrates. By careful analysis of their properties, the influence of substrate stoichiometry, Fe3O4 thin film thickness, antiphase boundaries on the magnetic properties can be separated. In particular, the controversial enhanced magnetic moment in ultrathin films (<5 nm) was confirmed to be related to the substrate stoichiometry, specifically the migration of oxygen vacancies into the Fe3O4 thin films. The multilayer concept can be employed with many other such systems and offers methods of tuning the properties of thin magnetic oxides.
NASA Astrophysics Data System (ADS)
Tung, J. C.; Guo, G. Y.
2010-03-01
An extensive ab initio study of the physical properties of both linear and zigzag atomic chains of all 4d and 5d transition metals (TMs) within the generalized gradient approximation by using the accurate projector-augmented wave method, has been carried out. The atomic structures of equilibrium and metastable states were theoretically determined. All the TM linear chains are found to be unstable against the corresponding zigzag structures. All the TM chains, except Nb, Ag, and La, have a stable (or metastable) magnetic state in either the linear or zigzag or both structures. Magnetic states appear also in the sufficiently stretched Nb and La linear chains and in the largely compressed Y and La chains. The spin magnetic moments in the Mo, Tc, Ru, Rh, W, Re chains could be large (≥1.0μB/atom) . Structural transformation from the linear to zigzag chains could suppress the magnetism already in the linear chain, induce the magnetism in the zigzag structure, and also cause a change in the magnetic state (ferromagnetic to antiferromagnetic or vice verse). The calculations including the spin-orbit coupling reveal that the orbital moments in the Zr, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir, and Pt chains could be rather large (≥0.1μB/atom) . Importantly, large magnetic anisotropy energy (≥1.0meV/atom) is found in most of the magnetic TM chains, suggesting that these nanowires could have fascinating applications in ultrahigh-density magnetic memories and hard disks. In particular, giant magnetic anisotropy energy (≥10.0meV/atom) could appear in the Ru, Re, Rh, and Ir chains. Furthermore, the magnetic anisotropy energy in several elongated linear chains could be as large as 40.0 meV/atom. A spin-reorientation transition occurs in the Ru, Ir, Ta, Zr, La, Ta, and Ir linear chains when they are elongated. Remarkably, all the 5d as well as Tc and Pd chains show the colossal magnetic anisotropy (i.e., it is impossible to rotate magnetization into certain directions
NASA Astrophysics Data System (ADS)
de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.
2008-04-01
In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.
NASA Astrophysics Data System (ADS)
Baryshevsky, V. G.
2017-07-01
The phenomena of spin rotation and depolarization of high-energy particles in crystals in the range of high energies that will be available at Hadron Collider (LHC) and Future Circular Collider (FCC) provides a unique possibility of measuring the anomalous magnetic moment of charged and neutral charm and beauty hyperons and quadrupole moment of Ω -hyperon. Crystals with polarized nuclei give opportunities for measuring spin-dependent interactions of short lived particles with nuclei and measurement of a particle polarization.
Reactor antineutrino fluxes – Status and challenges
Huber, Patrick
2016-04-22
Here, we describe the current understanding of reactor antineutrino fluxes and point out some recent developments. This is not intended to be a complete review of this vast topic but merely a selection of observations and remarks, which despite their incompleteness, will highlight the status and the challenges of this field.
Magnetic Dipole Moment Measurements of Picosecond States in Even and Odd Heavy Nuclei
NASA Astrophysics Data System (ADS)
Ballon, Douglas Jude
The perturbed angular correlation and transient field technique is used to measure the precession of nuclear magnetic moments of low lying excited states in isotopes of silver, neodymium, samarium, and gadolinium. The precession measurements are used to explore three main areas of study. First, from the measurements made on ('150)Sm traversing gadolinium targets, the temperature dependence of the transient hyperfine field is deduced at ('150)Sm nuclei traveling at 2 < v/v(,0) < 4. These are compared with similar measurements made using iron targets. Second, the deduced values of the g-factors of the 2(,1)('+) states in even neodymium, samarium and gadolinium isotopes are discussed in connection with a possible proton shell closure at Z = 64. Third, the deduced values of the g-factors of the 3/2(,1)('-) and 5/2(,1)('-) states of ('107,109)Ag are compared to various theoretical predictions in order to explore any simple relationships that may exist between these states and the first 2(,1)('+) states of neighboring even-even nuclei. The following is a list of g-factors that were measured during the course of this work: (UNFORMATTED TABLE FOLLOWS). g(('107)Ag, 3/2(,1)('-)) = 0.607 (119). g(('109)Ag, 3/2(,1)('-)) = 0.661 (105). g(('107)Ag, 5/2(,1)('-)) = 0.409 (66). g(('109)Ag, 5/2(,1)('-)) = 0.287 (57). g(('144)Nd, 2(,1)('+)) = 0.166 (41). g(('146)Nd, 2(,1)('+)) = 0.312 (49). g(('148)Nd, 2(,1)('+)) = 0.411 (42). g(('150)Nd,2(,1)('+)) = 0.418 (38). g(('148)Sm, 2(,1)('+)) = 0.301 (33). g(('150)Sm, 2(,1)('+)) = 0.381 (27). g(('152)Gd, 2(,1)('+)) = 0.444 (40). (TABLE ENDS). The results of the temperature dependence experiment show deviations from an earlier measurement made using thulium in iron. The g-factors measured in the lighter isotopes of neodymium and samarium are significantly below the collective Z/A value. Fair agreement with the data can be obtained if proton shell closure is assumed at Z = 64 for N < 88. The measured g-factors in the silver isotopes
Afach, S.; Fertl, M.; Franke, B. E-mail: bernhard.lauss@psi.ch; Kirch, K.; Bison, G.; Burri, F.; Chowdhuri, Z.; Daum, M.; Henneck, R.; Lauss, B. E-mail: bernhard.lauss@psi.ch; Meier, M.; Schmidt-Wellenburg, P.; Zsigmond, G.; Bodek, K.; Zejma, J.; Grujic, Z.; Kasprzak, M.; Weis, A.; Hélaine, V.; Koch, H.-C.; and others
2014-08-28
The Surrounding Field Compensation (SFC) system described in this work is installed around the four-layer Mu-metal magnetic shield of the neutron electric dipole moment spectrometer located at the Paul Scherrer Institute. The SFC system reduces the DC component of the external magnetic field by a factor of about 20. Within a control volume of approximately 2.5 m × 2.5 m × 3 m, disturbances of the magnetic field are attenuated by factors of 5–50 at a bandwidth from 10{sup −3} Hz up to 0.5 Hz, which corresponds to integration times longer than several hundreds of seconds and represent the important timescale for the neutron electric dipole moment measurement. These shielding factors apply to random environmental noise from arbitrary sources. This is achieved via a proportional-integral feedback stabilization system that includes a regularized pseudoinverse matrix of proportionality factors which correlates magnetic field changes at all sensor positions to current changes in the SFC coils.
Orgassa, D.; Fujiwara, H.; Schulthess, T. C.; Butler, W. H.
2000-05-01
Using half-metallic ferromagnets in spin-dependent devices, like spin valves and ferromagnetic tunnel junctions, is expected to increase the device performance. However, using the half-metallic ferromagnet NiMnSb in such devices led to much less than ideal results. One of the possible sources for this behavior is atomic disorder. First-principles calculations of the influence of atomic disorder on the electronic structure of NiMnSb underline the sensitivity of half-metallic properties in NiMnSb to atomic disorder. In this article, we report on the disorder dependence of the total magnetic moment calculated by applying the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation. We consider the following types of disorder: (1) intermixing of Ni and Mn, (2) partial occupancy of a normally vacant lattice site by Ni and Mn, and (3) partial occupancy of this site by Mn and Sb. In all cases the composition is kept stoichiometric. All three types of disorder decrease the moment monotonically with increasing disorder levels. For the experimentally seen disorder of 5% Mn and 5% Sb on the normally vacant lattice site, the total moment is decreased by 4.1%. The results suggest that precise measurement of the saturation magnetization of NiMnSb thin films can give information on the disorder. (c) 2000 American Institute of Physics.
NASA Astrophysics Data System (ADS)
Narayan Vaidya, Arvind; Barbosa da Silva Filho, Pedro
1999-09-01
The Green function for a charged spin- 1/2 particle with anomalous magnetic moment in the presence of a plane-wave external electromagnetic field is calculated and shown to be simply related to the free-particle one.
Cai, Y. P.; Chesnel, K. Trevino, M.; Westover, A.; Turley, S.; Harrison, R. G.; Hancock, J. M.; Scherz, A.; Reid, A.; Wu, B.; Graves, C.; Wang, T.; Liu, T.; Dürr, H.
2014-05-07
The orbital and spin contributions to the magnetic moment of Fe in Fe{sub 3}O{sub 4} nanoparticles were measured using X-ray magnetic circular dichroism (XMCD). Nanoparticles of different sizes, ranging from 5 to 11 nm, were fabricated via organic methods and their magnetic behavior was characterized by vibrating sample magnetometry (VSM). An XMCD signal was measured for three different samples at 300 K and 80 K. The extracted values for the orbital and spin contributions to the magnetic moment showed a quenching of the orbital moment and a large spin moment. The calculated spin moments appear somewhat reduced compared to the value expected for bulk Fe{sub 3}O{sub 4}. The spin moments measured at 80 K are larger than at 300 K for all the samples, revealing significant thermal fluctuations effects in the nanoparticle assemblies. The measured spin moment is reduced for the smallest nanoparticles, suggesting that the magnetic properties of Fe{sub 3}O{sub 4} nanoparticles could be altered when their size reaches a few nanometers.
NASA Astrophysics Data System (ADS)
Fagnard, J. F.; Morita, M.; Nariki, S.; Teshima, H.; Caps, H.; Vanderheyden, B.; Vanderbemden, P.
2016-12-01
Recent studies have shown that ferromagnetic materials can be used together with bulk high temperature superconductors in order to improve their magnetic trapped field. Remarkably, it has also been pointed out that ferromagnets can help in reducing the crossed field effect, namely the magnetization decay that is observed under the application of AC transverse magnetic fields. In this work, we pursue a detailed study of the influence of the geometry of the ferromagnetic part on both trapped fields and crossed field effects. The magnetic properties of the hybrid superconducting/soft ferromagnetic structures are characterized by measuring the magnetic moment with a bespoke magnetometer and the local magnetic field density with Hall probes. The results are interpreted by means of 2D and 3D numerical models yielding the distribution of the superconducting currents as a function of the ferromagnet geometry. We examine in details the distortion of the shielding superconducting currents distribution in hybrid structures subjected to crossed magnetic fields. These results confirm the existence of an optimum thickness of the ferromagnet, which depends on the saturation magnetization of the ferromagnetic material and the current density of the superconductor. A hybrid structure providing an efficient protection against the crossed magnetic field while maintaining the magnetic induction along the axis of the structure is suggested. The limitations of the 2D modelling in this configuration are discussed.
Experimental evidence of Cr magnetic moments at low temperature in Cr2A(A=Al, Ge)C.
Jaouen, M; Bugnet, M; Jaouen, N; Ohresser, P; Mauchamp, V; Cabioc'h, T; Rogalev, A
2014-04-30
From x-ray magnetic circular dichroism experiments performed at low temperature on Cr2AlC and Cr2GeC thin films, it is evidenced that Cr atoms carry a net magnetic moment in these ternary phases. It is shown that the Cr magnetization of the Al-based compound nearly vanished at 100 K in agreement with what has been recently observed on bulk. X-ray linear dichroism measurements performed at various angles of incidence and temperatures clearly demonstrate the existence of a charge ordering along the c axis of the structure of Cr2AlC. All these experimental observations support, in part, theoretical calculations claiming that Cr dd correlations have to be considered to correctly describe the structure and properties of these Cr-based ternary phases.
NASA Astrophysics Data System (ADS)
Maslova, N. S.; Mantsevich, V. N.; Arseyev, P. I.
2017-02-01
We perform theoretical investigation of the localized state dynamics in the presence of interaction with the reservoir and Coulomb correlations. We analyze kinetic equations for electron occupation numbers with different spins taking into account high order correlation functions for the localized electrons. We reveal that in the stationary state electron occupation numbers with the opposite spins always have the same value - the stationary state is a "paramagnetic" one. "Magnetic" properties can appear only in the non-stationary characteristics of the single-impurity Anderson model and in the dynamics of the localized electrons second order correlation functions. We found, that for deep energy levels and strong Coulomb correlations, relaxation time for initial "magnetic" state can be several orders larger than for "paramagnetic" one. So, long-living "magnetic" moment can exist in the system. We also found non-stationary spin polarized currents flowing in opposite directions for the different spins in the particular time interval.
Saari, M. M. Sakai, K.; Kiwa, T.; Tsukada, K.; Sasayama, T.; Yoshida, T.
2015-05-07
We developed a highly sensitive AC/DC magnetometer using a high-temperature superconductor superconducting quantum interference device for the evaluation of magnetic nanoparticles in solutions. Using the developed system, we investigated the distribution of magnetic moments of iron oxide multi-core particles of 100 nm at various iron concentrations that are lower than 96 μg/ml by analyzing the measured magnetization curves. Singular value decomposition and non-regularized non-negative least-squares methods were used during the reconstruction of the distribution. Similar distributions were obtained for all concentrations, and the iron concentration could be determined from the measured magnetization curves. The measured harmonics upon the excitation of AC and DC magnetic fields curves agreed well with the harmonics simulated based on the reconstructed magnetization curves, implying that the magnetization curves of magnetic nanoparticles were successfully obtained as we will show in the article. We compared the magnetization curves between multi-core particles of 100 nm and 130 nm, composed of 12-nm iron oxide nanoparticles. A distinctive magnetic property between the 100 nm and 130 nm particles in low-concentration solutions was successfully characterized. The distribution characteristic of magnetic moments suggests that the net magnetic moment in a multi-core particle is affected by the size of the magnetic cores and their degree of aggregation. Exploration of magnetic properties with high sensitivity can be expected using the developed system.
Evidence for local moment magnetism in superconducting FeTe0.35 Se 0.65
NASA Astrophysics Data System (ADS)
Xu, Guangyong; Xu, Zhijun; Wen, Jinsheng; Chi, Songxue; Ku, Wei; Gu, Genda; Tranquada, John
2011-03-01
We investigate the temperature evolution (from 5~K to 300~K) of low energy spin fluctuations in Fe-based superconductor FeTe 0.35 Se 0.65 (Tc ~ 14 ~K) via inelastic neutron scattering. The magnetic excitation spectrum in the superconducting phase appears qualitatively similar to those observed in other Fe-based superconductors, with a spin gap (at about 5~meV) and a resonance peak at ℏω ~ 6.5 ~meV. At higher temperatures, the spectral weight of the low-temperature resonance is found to redistribute to lower energies below the spin gap. A significant moment (0.26μB / Fe) is found for the integrated spectral weight below merely ℏω ~ 12 ~meV, with nearly no temperature dependence up to 300K, indicating existence of strong local moments.
Atomic moments in Mn_{2}CoAl thin films analyzed by X-ray magnetic circular dichroism
Jamer, M. E.; Assaf, B. A.; Sterbinsky, G. E.; Arena, D. A.; Heiman, D.
2014-12-05
Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn_{2}CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. Results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value.
NASA Astrophysics Data System (ADS)
Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar
2016-07-01
The ground state magnetic moments and the low-lying magnetic dipole (Ml) transitions from the ground to excited states in heavy deformed odd-mass 181Ta have been microscopically investigated on the basis of the quasiparticle-phonon nuclear model (QPNM). The problem of the spurious state mixing in M1 excitations is overcome by a restoration method allowing a self-consistent determination of the separable effective restoration forces. Due to the self-consistency of the method, these effective forces contain no arbitrary parameters. The results of calculations are compared with the available experimental data, the agreement being reasonably satisfactory.
Neutron β -decay as the origin of IceCube's PeV (anti)neutrinos
NASA Astrophysics Data System (ADS)
Anchordoqui, Luis A.
2015-01-01
Motivated by the indications of a possible deficit of muon tracks in the first three-year equivalent data set of IceCube we investigate the possibility that the astrophysical (anti)neutrino flux (in the PeV energy range) could originate from β -decay of relativistic neutrons. We show that to accommodate IceCube observations it is necessary that only about 1% to 10% of the emitted cosmic rays in the energy decade 108.5≲ECR/GeV ≲109.5 , yielding antineutrinos on Earth (1 05.5≲Eν ¯/GeV ≲1 06.5 ), are observed. Such a strong suppression can be explained assuming magnetic shielding of the secondary protons which diffuse in extragalactic magnetic fields of strength 10 ≲B /nG ≲100 and coherence length ≲Mpc .
2014-01-01
Co-doped SnO2 thin films were grown by sputtering technique on SiO2/Si(001) substrates at room temperature, and then, thermal treatments with and without an applied magnetic field (HTT) were performed in vacuum at 600°C for 20 min. HTT was applied parallel and perpendicular to the substrate surface. Magnetic M(H) measurements reveal the coexistence of a strong antiferromagnetic (AFM) signal and a ferromagnetic (FM) component. The AFM component has a Néel temperature higher than room temperature, the spin axis lies parallel to the substrate surface, and the highest magnetic moment m =7 μB/Co at. is obtained when HTT is applied parallel to the substrate surface. Our results show an enhancement of FM moment per Co+2 from 0.06 to 0.42 μB/Co at. for the sample on which HTT was applied perpendicular to the surface. The FM order is attributed to the coupling of Co+2 ions through electrons trapped at the site of oxygen vacancies, as described by the bound magnetic polaron model. Our results suggest that FM order is aligned along [101] direction of Co-doped SnO2 nanocrystals, which is proposed to be the easy magnetization axis. PMID:25489286
Loya-Mancilla, Sagrario M; Poddar, Pankaj; Das, Raja; Ponce, Hilda E Esparza; Templeton-Olivares, Ivan L; Solis-Canto, Oscar O; Ornelas-Gutierrez, Carlos E; Espinosa-Magaña, Francisco; Olive-Méndez, Sion F
2014-01-01
Co-doped SnO2 thin films were grown by sputtering technique on SiO2/Si(001) substrates at room temperature, and then, thermal treatments with and without an applied magnetic field (HTT) were performed in vacuum at 600°C for 20 min. HTT was applied parallel and perpendicular to the substrate surface. Magnetic M(H) measurements reveal the coexistence of a strong antiferromagnetic (AFM) signal and a ferromagnetic (FM) component. The AFM component has a Néel temperature higher than room temperature, the spin axis lies parallel to the substrate surface, and the highest magnetic moment m =7 μB/Co at. is obtained when HTT is applied parallel to the substrate surface. Our results show an enhancement of FM moment per Co(+2) from 0.06 to 0.42 μB/Co at. for the sample on which HTT was applied perpendicular to the surface. The FM order is attributed to the coupling of Co(+2) ions through electrons trapped at the site of oxygen vacancies, as described by the bound magnetic polaron model. Our results suggest that FM order is aligned along [101] direction of Co-doped SnO2 nanocrystals, which is proposed to be the easy magnetization axis.
NASA Technical Reports Server (NTRS)
Stuart, Keith; Bartosh, Blake
1993-01-01
Innovative Information Systems (IIS), Inc. is in the process of designing and fabricating a high bandwidth force and moment measuring device (i.e. the Magnetic Thruster Test Stand). This device will use active magnetic suspension to allow direct measurements of the forces and torques generated by the rocket engines of the missile under test. The principle of operation of the Magnetic Thruster Test Stand (MTTS) is based on the ability to perform very precise, high bandwidth force and position measurements on an object suspended in a magnetic field. This ability exists due to the fact that the digital servo control mechanism that performs the magnetic suspension uses high bandwidth (10 kHz) position data (via an eddy-current proximity sensor) to determine the amount of force required to maintain stable suspension at a particular point. This force is converted into required electromagnet coil current, which is then output to a current amplifier driving the coils. A discussion of how the coil current and magnetic gap distance (the distance between the electromagnet and the object being suspended) is used to determine the forces being applied from the suspended assembly is presented.
NASA Astrophysics Data System (ADS)
Biswas, Aritra
2015-10-01
Discovery of an electric dipole moment in neutrons (nEDM) would be a novel instance of CP violation, with implications for extending the Standard Model and potentially helping explain matter-antimatter asymmetry. Experiments using shifts in polarized neutron spin-precession frequency to measure the nEDM are prone to a geometric phase (GP) effect, caused by gradients of the magnetic field, that can create a false signal. Preventing the GP effect requires precise engineering to create a space-uniform magnetic field. We present a third-scale prototype of a shielded magnet suitable for a more precise nEDM measurement, with improvements over earlier models. The field is produced by a cosθ coil wound with superconducting (SC) wire. Two cylindrical shields made of ferromagnetic Metglas and SC lead surround the magnet; the lead shield is closed on top and bottom with SC lead endcaps. An aluminum shell surrounds these components and serves as a vacuum chamber, cooling its interior to 4 K such that the coil wire and lead shield become SC. A cavity in this shell serves as a warm bore, allowing a magnetic probe to explore the field around fiducial volumes which will be used to measure the nEDM in the full-scale experiment. The magnetic field profile of this prototype is presented.
Ouedraogo, Serge Aristide
2008-12-01
A search for the muon neutrino magnetic moment was conducted using the Mini-BooNE low energy neutrino data. The analysis was performed by analyzing the elastic scattering interactions of muon neutrinos on electrons. The analysis looked for an excess of elastic scattering events above the Standard Model prediction from which a limit on the neutrino magnetic could be set. In this thesis, we report an excess of 15.3 ± 6.6(stat)±4.1(syst) v_{μ}e events above the expected background. At 90% C.L., we derived a limit on the muon neutrino magnetic moment of 12.7 x 10^{-10} μ_{B}. The other analysis reported in this thesis is a measurement of charged current single pion production (CCπ^{+}) to charged current quasi elastic (CCQE) interactions cross sections ratio. This measurement was performed with two different fitting algorithms and the results from both fitters are consistent with each other.
NASA Astrophysics Data System (ADS)
Ma, X. B.; Zhao, Y. F.; Chen, Y. X.; Zhong, W. L.; An, F. P.
2017-10-01
The antineutrino flux from spent nuclear fuel (SNF) is an important source of uncertainty when making estimates of a reactor neutrino flux. However, to determine the contribution from SNF, sufficient data is needed such as the amount of spent fuel in the pool, the time after discharged from the reactor core, the burnup of each assembly, and the antineutrino spectrum of each isotope in the SNF. A method to calculate this contribution is proposed. A reactor simulation code verified against experimental data has been used to simulate fuel depletion by taking into account more than 2000 isotopes and fission products, the quantity of SNF in each of the six spent fuel pools, and the time variation of the antineutrino spectra after SNF discharging from the core. Results show that the SNF contribution to the total antineutrino flux is about 0.26%-0.34%, and the shutdown impact is about 20%. The SNF spectrum alters the softer part of the antineutrino spectra, and the maximum contribution from the SNF is about 3.0%. Nevertheless, there is an 18% difference between the line evaluate method and under evaluate method. In addition, non-equilibrium effects are also discussed, and the results are compatible considering the uncertainties.
Kondo correlations formation and the local magnetic moment dynamics in the Anderson model
NASA Astrophysics Data System (ADS)
Maslova, N. S.; Arseyev, P. I.; Mantsevich, V. N.
2017-02-01
We investigated the typical time scales of the Kondo correlations formation for the single-state Anderson model, when coupling to the reservoir is switched on at the initial time moment. The influence of the Kondo effect appearance on the system non-stationary characteristics was analyzed and discussed.
Manz, Thomas A; Sholl, David S
2011-12-13
The partitioning of electron spin density among atoms in a material gives atomic spin moments (ASMs), which are important for understanding magnetic properties. We compare ASMs computed using different population analysis methods and introduce a method for computing density derived electrostatic and chemical (DDEC) ASMs. Bader and DDEC ASMs can be computed for periodic and nonperiodic materials with either collinear or noncollinear magnetism, while natural population analysis (NPA) ASMs can be computed for nonperiodic materials with collinear magnetism. Our results show Bader, DDEC, and (where applicable) NPA methods give similar ASMs, but different net atomic charges. Because they are optimized to reproduce both the magnetic field and the chemical states of atoms in a material, DDEC ASMs are especially suitable for constructing interaction potentials for atomistic simulations. We describe the computation of accurate ASMs for (a) a variety of systems using collinear and noncollinear spin DFT, (b) highly correlated materials (e.g., magnetite) using DFT+U, and (c) various spin states of ozone using coupled cluster expansions. The computed ASMs are in good agreement with available experimental results for a variety of periodic and nonperiodic materials. Examples considered include the antiferromagnetic metal organic framework Cu3(BTC)2, several ozone spin states, mono- and binuclear transition metal complexes, ferri- and ferro-magnetic solids (e.g., Fe3O4, Fe3Si), and simple molecular systems. We briefly discuss the theory of exchange-correlation functionals for studying noncollinear magnetism. A method for finding the ground state of systems with highly noncollinear magnetism is introduced. We use these methods to study the spin-orbit coupling potential energy surface of the single molecule magnet Fe4C40H52N4O12, which has highly noncollinear magnetism, and find that it contains unusual features that give a new interpretation to experimental data.
Gd-doped BaSnO{sub 3}: A transparent conducting oxide with localized magnetic moments
Alaan, Urusa S.; Shafer, Padraic; N'Diaye, Alpha T.; Arenholz, Elke; Suzuki, Y.
2016-01-25
We have synthesized transparent, conducting, paramagnetic stannate thin films via rare-earth doping of BaSnO{sub 3}. Gd{sup 3+} (4f{sup 7}) substitution on the Ba{sup 2+} site results in optical transparency in the visible regime, low resistivities, and high electron mobilities, along with a significant magnetic moment. Pulsed laser deposition was used to stabilize epitaxial Ba{sub 0.96}Gd{sub 0.04}SnO{sub 3} thin films on (001) SrTiO{sub 3} substrates, and compared with Ba{sub 0.96}La{sub 0.04}SnO{sub 3} and undoped BaSnO{sub 3} thin films. Gd as well as La doping schemes result in electron mobilities at room temperature that exceed those of conventional complex oxides, with values as high as 60 cm{sup 2}/V·s (n = 2.5 × 10{sup 20 }cm{sup −3}) and 30 cm{sup 2}/V·s (n = 1 × 10{sup 20 }cm{sup −3}) for La and Gd doping, respectively. The resistivity shows little temperature dependence across a broad temperature range, indicating that in both types of films the transport is not dominated by phonon scattering. Gd-doped BaSnO{sub 3} films have a strong magnetic moment of ∼7 μ{sub B}/Gd ion. Such an optically transparent conductor with localized magnetic moments may unlock opportunities for multifunctional devices in the design of next-generation displays and photovoltaics.
NASA Astrophysics Data System (ADS)
White, G.; Rikovska, J.; Stone, N. J.; Copnell, J.; Towner, I. S.; Oros, A. M.; Heyde, K.; Fogelberg, B.; Jacobsson, L.; Gustavsson, F.
1998-09-01
On-line low temperature nuclear orientation (OLNO) experiments have been performed on the odd- A Te isotopes 131Te and 133Te using the technique of nuclear magnetic resonance on oriented nuclei (NMR/ON). The magnetic moments of the isomeric {11}/{2 -} states have been measured extending the known data on these states in the Te isotopes up to the neutron shell closure at N = 82. The contribution to the {11}/{2 -} magnetic moment in 133Te due to core polarisation is calculated using an RPA shell model as well as corrections to the magnetic dipole operator caused by mesonic exchange currents. The neutron number dependence of the magnetic moments of the {11}/{2 -} isomers in heavy Te isotopes is discussed in terms of particle-core coupling model (PCM) calculations.
The reaction gammap-->pi0gamma'p and the magnetic dipole moment of the Delta+ 1232 resonance.
Kotulla, M; Ahrens, J; Annand, J R M; Beck, R; Caselotti, G; Fog, L S; Hornidge, D; Janssen, S; Krusche, B; McGeorge, J C; McGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Pfeiffer, M; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Watts, D P
2002-12-30
The reaction gammap-->pi(0)gamma'p has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between sqrt[s]=1221-1331 MeV. The cross section's differential in angle and energy have been determined for the photon gamma' in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the Delta(+)(1232) resonance and, for the first time, a value of mu(Delta(+))=[2.7(+1.0)(-1.3)(stat)+/-1.5(syst)+/-3(theor)]mu(N) has been extracted.
Sharma, Neetika; Dahiya, Harleen; Chatley, P. K.; Gupta, Manmohan
2010-04-01
Magnetic moments of the low lying and charmed spin (1/2){sup +} and spin (3/2){sup +} baryons have been calculated in the SU(4) chiral constituent quark model ({chi}CQM) by including the contribution from cc fluctuations. Explicit calculations have been carried out for the contribution coming from the valence quarks, ''quark sea'' polarizations and their orbital angular momentum. The implications of such a model have also been studied for magnetic moments of the low lying spin (3/2){sup +{yields}}(1/2){sup +} and (1/2){sup +{yields}}(1/2){sup +} transitions as well as the transitions involving charmed baryons. The predictions of {chi}CQM not only give a satisfactory fit for the baryons where experimental data is available but also show improvement over the other models. In particular, for the case of {mu}(p), {mu}({Sigma}{sup +}), {mu}({Xi}{sup 0}), {mu}({Lambda}), Coleman-Glashow sum rule for the low lying spin (1/2){sup +} baryons and {mu}({Delta}{sup +}), {mu}({Omega}{sup -}) for the low lying spin (3/2){sup +} baryons, we are able to achieve an excellent agreement with data. For the spin (1/2){sup +} and spin (3/2){sup +} charmed baryon magnetic moments, our results are consistent with the predictions of the QCD sum rules, light cone sum rules and spectral sum rules. For the cases where light quarks dominate in the valence structure, the sea and orbital contributions are found to be fairly significant however, they cancel in the right direction to give the correct magnitude of the total magnetic moment. On the other hand, when there is an excess of heavy quarks, the contribution of the quark sea is almost negligible, for example, {mu}({Omega}{sub c}{sup 0}), {mu}({Lambda}{sub c}{sup +}), {mu}({Xi}{sub c}{sup +}), {mu}({Xi}{sub c}{sup 0}), {mu}({Omega}{sub cc}{sup +}), {mu}({Omega}{sup -}), {mu}({Omega}{sub c}*{sup 0}), {mu}({Omega}{sub cc}*{sup +}), and {mu}({Omega}{sub ccc}*{sup ++}). The effects of configuration mixing and quark masses have also been
A CF4 TPC to measure the ν¯e magnetic moment at a nuclear reactor.
NASA Astrophysics Data System (ADS)
Broggini, C.; Jörgens, V.; Treichel, M.; Twerenbold, D.; Vuilleumier, J.-L.
An experiment is described which offers a significant improvement for the measurement of the ν¯ee- cross section at low energy. The experiment will be sensitive to a neutrino magnetic moment down to a few 10-11 Bohr magnetons, on the level of that introduced to explain the solar neutrino puzzle. The detector, to be placed close to a nuclear reactor, is a 1 m3 Time Pojection Chamber surrounded by an active shielding. The key point of the experiment is the use of tetrafluoromethane, CF4, at the pressure of 5 bar in the TPC.
NASA Astrophysics Data System (ADS)
Birkner, Bastian; Pachniowski, Daniel; Sandner, Andreas; Ostler, Markus; Seyller, Thomas; Fabian, Jaroslav; Ciorga, Mariusz; Weiss, Dieter; Eroms, Jonathan
2013-02-01
We present results of nonlocal and three-terminal (3T) spin precession measurements on spin injection devices fabricated on epitaxial graphene on SiC. The measurements were performed before and after an annealing step at 150 ∘C for 15 minutes in vacuum. The values of spin relaxation length Ls and spin relaxation time τs obtained after annealing are reduced by a factor 2 and 4, respectively, compared to those before annealing. An apparent discrepancy between spin diffusion constant Ds and charge diffusion constant Dc can be resolved by investigating the temperature dependence of the g factor, which is consistent with a model for paramagnetic magnetic moments.
CeRh{sub 3}B{sub 2}: A ferromagnet with anomalously large Ce 5d spin and orbital magnetic moments
Yaouanc, A.; Dalmas de Reotier, P.; Sanchez, J.; Tschentscher, T.; Lejay, P.
1998-01-01
We report a high-energy magnetic-Compton-scattering study performed on the ferromagnet CeRh{sub 3}B{sub 2}. This technique solely measures the electron spin magnetic moments. In contrast to a number of Ce intermetallics with nonmagnetic elements, the Ce 5d spin moment is found to be large and parallel to the Ce 4f spin moment. Therefore the Kondo effect does not play a key role for CeRh{sub 3}B{sub 2}. The inferred large Ce 5d orbital magnetic moment is a signature of the strong spin-orbit interaction for the Ce 5d band. {copyright} {ital 1998} {ital The American Physical Society}
Cooperative Monitoring of Reactors with Antineutrino Detectors
NASA Astrophysics Data System (ADS)
Keefer, Greg
2010-11-01
The current state-of-the-art in antineutrino detection is such that it is now possible to monitor the operational status, power levels and fissile content of nuclear reactors in real-time at standoff distances of a few tens of meters, well outside of the reactor containment. This has been demonstrated at civilian power reactors in both Russia and the United States. In the last few years, the International Atomic Energy Agency has begun to consider the potential of this technology for its reactor safeguards regime. In this talk, I describe the state of the art for this application, and emphasize the natural overlap with ongoing efforts in fundamental physics to measure the oscillations of antineutrinos using reactor sources.
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J. Zaluzec, Nestor; Leifer, Klaus
2015-08-17
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J. Zaluzec, Nestor; Leifer, Klaus
2015-01-01
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features. PMID:26278134
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J Zaluzec, Nestor; Leifer, Klaus
2015-08-17
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.
Antineutrino and gamma emission from the OSIRIS research reactor
NASA Astrophysics Data System (ADS)
Giot, Lydie; Fallot, Muriel
2017-09-01
For the first time, the summation method has been coupled with a complete reactor model, in order to predict the antineutrino emission of a research reactor. This work, discussed in the first part of this paper, allows us to predict the low energy part of the antineutrino spectrum, evidencing the important contribution of actinides to the antineutrino emission. Experimental conditions at short distance from research reactors are challenging, because the reactor itself produces huge gamma background that induce accidental and correlated backgrounds in an antineutrino target. The understanding of this background is of utmost importance and triggered the second part of the work presented here.
NASA Technical Reports Server (NTRS)
Eskins, Jonathan
1988-01-01
The problem of determining the forces and moments acting on a wind tunnel model suspended in a Magnetic Suspension and Balance System is addressed. Two calibration methods were investigated for three types of model cores, i.e., Alnico, Samarium-Cobalt, and a superconducting solenoid. Both methods involve calibrating the currents in the electromagnetic array against known forces and moments. The first is a static calibration method using calibration weights and a system of pulleys. The other method, dynamic calibration, involves oscillating the model and using its inertia to provide calibration forces and moments. Static calibration data, found to produce the most reliable results, is presented for three degrees of freedom at 0, 15, and -10 deg angle of attack. Theoretical calculations are hampered by the inability to represent iron-cored electromagnets. Dynamic calibrations, despite being quicker and easier to perform, are not as accurate as static calibrations. Data for dynamic calibrations at 0 and 15 deg is compared with the relevant static data acquired. Distortion of oscillation traces is cited as a major source of error in dynamic calibrations.
Bounds on the solar antineutrino total flux and energy spectrum from the SK experiment
NASA Astrophysics Data System (ADS)
Torrente-Lujan, E.
2000-11-01
A search for inverse beta decay electron antineutrinos has been carried out using the 825 days sample of solar data obtained at SK. The absence of a significant signal, that is, contributions to the total SK background and their angular variations has set upper bounds on (a) the absolute flux of solar antineutrinos originated from 8B neutrinos Φν¯(8B)<=1.8×105 cm-2s-1 which is equivalent to an averaged conversion probability bound of /P<3.5% (SSM-BP98 model) and (b) their differential energy spectrum, the conversion probability is smaller than 8% for all Ee,vis>6.5 MeV going down the 5% level above Ee,vis~10 MeV. It is shown that an antineutrino flux would have the net effect of enhancing the SK signal at hep neutrino energies. The magnitude of this enhancement would highly depend on the, otherwise rather uncertain at this moment, steepness of the solar neutrino spectrum at these energies.