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Sample records for high spin cobaltii

  1. Synthesis and Temperature-Induced Structural Phase and Spin Transitions in Hexadecylboron-Capped Cobalt(II) Hexachloroclathrochelate and Its Diamagnetic Iron(II)-Encapsulating Analogue.

    PubMed

    Vologzhanina, Anna V; Belov, Alexander S; Novikov, Valentin V; Dolganov, Alexander V; Romanenko, Galina V; Ovcharenko, Victor I; Korlyukov, Alexander A; Buzin, Mikhail I; Voloshin, Yan Z

    2015-06-15

    Template condensation of dichloroglyoxime with n-hexadecylboronic acid on the corresponding metal ion as a matrix under vigorous reaction conditions afforded n-hexadecylboron-capped iron and cobalt(II) hexachloroclathrochelates. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-vis, (1)H and (13)C{(1)H} NMR, (57)Fe Mössbauer spectroscopies, SQUID magnetometry, electron paramagnetic resonance, and cyclic voltammetry (CV) and by X-ray crystallography. The multitemperature single-crystal X-ray diffraction, SQUID magnetometry, and differential scanning calorimetry experiments were performed to study the temperature-induced spin-crossover [for the paramagnetic cobalt(II) complex] and the crystal-to-crystal phase transitions (for both of these clathrochelates) in the solid state. Analysis of their crystal packing using the molecular Voronoi polyhedra and the Hirshfeld surfaces reveals the structural rearrangements of the apical long-chain alkyl substituents resulting from such phase transitions being more pronounced for a macrobicyclic cobalt(II) complex. Its fine-crystalline sample undergoes the gradual and fully reversible spin transition centered at approximately 225 K. The density functional theory calculated parameters for an isolated molecule of this cobalt(II) hexachloroclathrochelate in its low- and high-spin states were found to be in excellent agreement with the experimental data and allowed to localize the spin density within a macrobicyclic framework. CV of the cobalt(II) complex in the cathodic range contains one reversible wave assigned to the Co(2+/+) redox couple with the reduced anionic cobalt(I)-containing species stabilized by the electronic effect of six strong electron-withdrawing chlorine substituents. The quasireversible character of the Fe(2+/+) wave suggests that the anionic iron(I)-containing macrobicyclic species undergo substantial structural changes and side chemical reactions after such

  2. A highly selective and sensitive fluorescence assay for determination of copper(II) and cobalt(II) ions in environmental water and toner samples.

    PubMed

    Tsai, Chia-Yi; Lin, Yang-Wei

    2013-02-21

    In this study, a highly selective and sensitive fluorescence assay has been proposed for the determination of copper(II) and cobalt(II) ions in environmental water and toner samples. In the presence of hydrogen peroxide, copper(II) reacted with a new fluorescence reagent Amplex® UltraRed (AUR), forming a fluorescence product only at pH 7.0, while the fluorescence product of cobalt(II) with AUR formed only at pH 9.0. The fluorescence signal obtained was linear with respect to the copper(II) concentration over the range of 1.6-12.0 μM (R(2) = 0.988) and was linear with respect to the cobalt(II) concentration over the range of 45.0 nM to 1.0 μM (R(2) = 0.992). The limits of detection (at a signal-to-noise ratio of 3) for copper(II) and cobalt(II) were 0.17 μM and 14.0 nM, respectively. Our present approach is simpler, faster, and more cost-effective than other techniques for the detection of copper(II) and cobalt(II) ions in environmental water samples and that of copper(II) ions in toner samples.

  3. A four-coordinate cobalt(II) single-ion magnet with coercivity and a very high energy barrier

    PubMed Central

    Rechkemmer, Yvonne; Breitgoff, Frauke D.; van der Meer, Margarethe; Atanasov, Mihail; Hakl, Michael; Orlita, Milan; Neugebauer, Petr; Sarkar, Biprajit; van Slageren, Joris

    2016-01-01

    Single-molecule magnets display magnetic bistability of molecular origin, which may one day be exploited in magnetic data storage devices. Recently it was realised that increasing the magnetic moment of polynuclear molecules does not automatically lead to a substantial increase in magnetic bistability. Attention has thus increasingly focussed on ions with large magnetic anisotropies, especially lanthanides. In spite of large effective energy barriers towards relaxation of the magnetic moment, this has so far not led to a big increase in magnetic bistability. Here we present a comprehensive study of a mononuclear, tetrahedrally coordinated cobalt(II) single-molecule magnet, which has a very high effective energy barrier and displays pronounced magnetic bistability. The combined experimental-theoretical approach enables an in-depth understanding of the origin of these favourable properties, which are shown to arise from a strong ligand field in combination with axial distortion. Our findings allow formulation of clear design principles for improved materials. PMID:26883902

  4. Towards accurate estimates of the spin-state energetics of spin-crossover complexes within density functional theory: a comparative case study of cobalt(II) complexes.

    PubMed

    Vargas, Alfredo; Krivokapic, Itana; Hauser, Andreas; Lawson Daku, Latévi Max

    2013-03-21

    We report a detailed DFT study of the energetic and structural properties of the spin-crossover Co(ii) complex [Co(tpy)(2)](2+) (tpy = 2,2':6',2''-terpyridine) in the low-spin (LS) and the high-spin (HS) states, using several generalized gradient approximation and hybrid functionals. In either spin-state, the results obtained with the functionals are consistent with one another and in good agreement with available experimental data. Although the different functionals correctly predict the LS state as the electronic ground state of [Co(tpy)(2)](2+), they give estimates of the HS-LS zero-point energy difference which strongly depend on the functional used. This dependency on the functional was also reported for the DFT estimates of the zero-point energy difference in the HS complex [Co(bpy)(3)](2+) (bpy = 2,2'-bipyridine) [A. Vargas, A. Hauser and L. M. Lawson Daku, J. Chem. Theory Comput., 2009, 5, 97]. The comparison of the and estimates showed that all functionals correctly predict an increase of the zero-point energy difference upon the bpy → tpy ligand substitution, which furthermore weakly depends on the functionals, amounting to . From these results and basic thermodynamic considerations, we establish that, despite their limitations, current DFT methods can be applied to the accurate determination of the spin-state energetics of complexes of a transition metal ion, or of these complexes in different environments, provided that the spin-state energetics is accurately known in one case. Thus, making use of the availability of a highly accurate ab initio estimate of the HS-LS energy difference in the complex [Co(NCH)(6)](2+) [L. M. Lawson Daku, F. Aquilante, T. W. Robinson and A. Hauser, J. Chem. Theory Comput., 2012, 8, 4216], we obtain for [Co(tpy)(2)](2+) and [Co(bpy)(3)](2+) best estimates of and , in good agreement with the known magnetic behaviour of the two complexes.

  5. High-spin cobalt(II) ions in square planar coordination: structures and magnetism of the oxysulfides Sr2CoO2Cu2S2 and Ba2CoO2Cu2S2 and their solid solution.

    PubMed

    Smura, Catherine F; Parker, Dinah R; Zbiri, Mohamed; Johnson, Mark R; Gál, Zoltán A; Clarke, Simon J

    2011-03-02

    The antiferromagnetic structures of the layered oxychalcogenides (Sr(1-x)Ba(x))(2)CoO(2)Cu(2)S(2) (0 ≤ x ≤ 1) have been determined by powder neutron diffraction. In these compounds Co(2+) is coordinated by four oxide ions in a square plane and two sulfide ions at the apexes of an extremely tetragonally elongated octahedron; the polyhedra share oxide vertexes. The magnetic reflections present in the diffraction patterns can in all cases be indexed using a √2a × √2a × c expansion of the nuclear cell, and nearest-neighbor Co(2+) moments couple antiferromagnetically within the CoO(2) planes. The ordered magnetic moment of Co(2+) in Sr(2)CoO(2)Cu(2)S(2) (x = 0) is 3.8(1) μ(B) at 5 K, consistent with high-spin Co(2+) ions carrying three unpaired electrons and with an additional significant unquenched orbital component. Exposure of this compound to moist air is shown to result in copper deficiency and a decrease in the size of the ordered moment to about 2.5 μ(B); there is a strong correlation between the size of the long-range ordered moment and the occupancy of the Cu site. Both the tetragonal elongation of the CoO(4)S(2) polyhedron and the ordered moment in (Sr(1-x)Ba(x))(2)CoO(2)Cu(2)S(2) increase with increasing Ba content, and in Ba(2)CoO(2)Cu(2)S(2), which has Co(2+) in an environment that is close to purely square planar, the ordered moment of 4.5(1) μ(B) at 5 K is over 0.7 μ(B) larger than that in Sr(2)CoO(2)Cu(2)S(2), so the unquenched orbital component in this case is even larger than that observed in octahedral Co(2+) systems such as CoO. The experimental observations of antiferromagnetic ground states and the changes in properties resulting from replacement of Sr by Ba are supported by ab initio calculations on Sr(2)CoO(2)Cu(2)S(2) and Ba(2)CoO(2)Cu(2)S(2). The large orbital moments in these systems apparently result from spin-orbit mixing of the unequally populated d(xz), d(yz), and d(z(2)) orbitals, which are reckoned to be almost degenerate

  6. Pairing Correlations at High Spins

    NASA Astrophysics Data System (ADS)

    Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.

    The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

  7. Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

    DOE PAGES

    Chen, Lei; Cui, Hui-Hui; Stavretis, Shelby E.; ...

    2016-12-07

    We synthesized and studied three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), using X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. Furthermore, the X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1–3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm–1 inmore » 1 to 26.6(3) cm–1 in 2 and 11.1(5) cm–1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm–1 for 1–3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). Finally, the electronic structures and the origin of magnetic anisotropy of 1–3 were revealed by calculations at the CASPT2/NEVPT2 level.« less

  8. Spin frustration in a family of pillared kagomé layers of high-spin cobalt(II) ions.

    PubMed

    Wang, Long-Fei; Li, Cui-Jin; Chen, Yan-Cong; Zhang, Ze-Min; Liu, Jiang; Lin, Wei-Quan; Meng, Yan; Li, Quan-Wen; Tong, Ming-Liang

    2015-02-02

    Based on the analogous kagomé [Co3 (imda)2 ] layers (imda=imidazole-4,5-dicarboxylate), a family of pillar-layered frameworks with the formula of [Co3 (imda)2 (L)3 ]⋅(L)n ⋅xH2 O (1: L=pyrazine, n=0, x=8; 2: L=4,4'-bipyridine, n=1, x=8; 3: L=1,4-di(pyridin-4-yl)benzene, n=1, x=13; 4: L=4,4'-di(pyridin-4-yl)-1,1'-biphenyl, n=1, x=14) have been successfully synthesized by a hydrothermal/solvothermal method. Single-crystal structural analysis shows a significant increase in the interlayer distances synchronized with the extension of the pillar ligands, namely, 7.092(3) (1), 10.921(6) (2), 14.780(5) (3), and 19.165(4) Å (4). Despite the wrinkled kagomé layers in complexes 2-4, comprehensive magnetic characterizations revealed weakening of interlayer magnetic interactions and an increase in the degree of frustration as the pillar ligand becomes longer from 1 to 4; this leads to characteristic magnetic ground states. For compound 4, which has the longest interlayer distance, the interlayer interaction is so weak that the magnetic properties observed within the range of temperature measured would correspond to the frustrated layer.

  9. Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

    SciTech Connect

    Chen, Lei; Cui, Hui-Hui; Stavretis, Shelby E.; Hunter, Seth C.; Zhang, Yi-Quan; Chen, Xue-Tai; Sun, Yi-Chen; Wang, Zhenxing; Song, You; Podlesnyak, Andrey A.; Ouyang, Zhong-Wen; Xue, Zi-Ling

    2016-12-07

    We synthesized and studied three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), using X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. Furthermore, the X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1–3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm–1 in 1 to 26.6(3) cm–1 in 2 and 11.1(5) cm–1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm–1 for 1–3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). Finally, the electronic structures and the origin of magnetic anisotropy of 1–3 were revealed by calculations at the CASPT2/NEVPT2 level.

  10. Study of the influence of the bridge on the magnetic coupling in cobalt(II) complexes.

    PubMed

    Fabelo, Oscar; Cañadillas-Delgado, Laura; Pasán, Jorge; Delgado, Fernando S; Lloret, Francesc; Cano, Joan; Julve, Miguel; Ruiz-Pérez, Catalina

    2009-12-07

    Two new cobalt(II) complexes of formula [Co(2)(bta)(H(2)O)(6)](n) x 2nH(2)O (1) and [Co(phda)(H(2)O)](n) x nH(2)O (2) [H(4)bta = 1,2,4,5-benzenetetracarboxylic acid, H(2)phda = 1,4-phenylenediacetic acid] have been characterized by single crystal X-ray diffraction. Compound 1 is a one-dimensional compound where the bta(4-) ligand acts as 2-fold connector between the cobalt(II) ions through two carboxylate groups in para-conformation. Triply bridged dicobalt(II) units occur within each chain, a water molecule, a carboxylate group in the syn-syn conformation, and an oxo-carboxylate with the mu(2)O(1);kappa(2)O(1),O(2) coordination mode acting as bridges. Compound 2 is a three-dimensional compound, where the phda(2-) group acts as a bridge through its two carboxylate groups, one of them adopting the mu-O,O' coordination mode in the syn-syn conformation and the other exhibiting the single mu(2)-O'' bridging mode. As in 1, chains of cobalt(II) ions occur in 2 with a water molecule, a syn-syn carboxylate group, and an oxo-carboxylate constitute the triply intrachain bridging skeleton. Each chain is linked to other four ones through the phda(2-) ligand, giving rise to the three-dimensional structure. The values of the intrachain cobalt-cobalt separation are 3.1691(4) (1) and 3.11499(2) A (2) whereas those across the phenyl ring of the extended bta(4-) (1) and phda(2-) (2) groups are 10.1120(6) and 11.4805(69 A, respectively. The magnetic properties of 1 and 2 have been investigated in the temperature range 1.9-300 K, and their analysis has revealed the occurrence of moderate intrachain ferromagnetic couplings [J = +5.4 (1) and +2.16 cm(-1) (2), J being the isotropic magnetic coupling parameter], the magnetic coupling through the extended bta(4-) and phda(2-) with cobalt-cobalt separations larger than 10 A being negligible. The nature and magnitude of the magnetic interactions between the high-spin cobalt(II) ions in 1 and 2 are compared to those of related systems and

  11. Single-ion magnet behaviour in mononuclear and two-dimensional dicyanamide-containing cobalt(ii) complexes.

    PubMed

    Switlicka-Olszewska, Anna; Palion-Gazda, Joanna; Klemens, Tomasz; Machura, Barbara; Vallejo, Julia; Cano, Joan; Lloret, Francesc; Julve, Miguel

    2016-06-21

    Three cobalt(ii) complexes of formulae [Co(dca)2(bim)4] (), [Co(dca)2(bim)2]n () and [Co(dca)2(bmim)2]n () [dca = dicyanamide, bim = 1-benzylimidazole and bmim = 1-benzyl-2-methylimidazole] were prepared and structurally analyzed by single-crystal X-ray crystallography. Compound is a mononuclear species where the cobalt(ii) ion is six-coordinate with four bim molecules in the equatorial positions [Co-Nbim = 2.1546(15) and 2.1489(15) Å] and two trans-positioned dca ligands [Co-Ndca = 2.1575(18) Å] in the axial sites of a somewhat distorted octahedral surrounding. The structures of and consist of two-dimensional grids of cobalt(ii) ions where each metal atom is linked to the other four metal centres by single dca bridges exhibiting the μ1,5-dca coordination mode [Co-Ndca = 2.190(3)-2.220(3) () and 2.127(3)-2.153(3) Å ()]. Two trans-coordinated bim ()/bmim () molecules achieve the six-coordination around each cobalt(ii) ion [Co-Nbim = 2.128(3)-2.134(4) Å () and Co-Nbmim = 2.156(3)-2.163(39) Å ()]. The values of the cobalt-cobalt separation through the single dca bridges are 8.927(2) and 8.968(2) Å in and 8.7110(5) and 8.7158(5) Å in . Magnetic susceptibility measurements for in the temperature range of 2.0-300 K reveal that these compounds behave as magnetically isolated high-spin cobalt(ii) ions with a significant orbital contribution to the magnetic moment. Alternating current (ac) magnetic susceptibility measurements for show a frequency dependence of out-of-phase susceptibility under static applied fields in the range of 500-2500 G, a feature which is characteristic of the single-ion magnet behaviour (SIM) of the Co(ii) ion in them. The values of the energy barrier for the magnetic relaxation (Ea) are 5.45-7.74 (), 4.53-9.24 () and 11.48-15.44 cm(-1) (). They compare well with those previously reported for the analogous dca-bridged 2D compound [Co(dca)2(atz)2]n () (Ea = 5.1 cm(-1) under an applied static field of 1000 G), which was the subject of a

  12. High spin isomer beam line at RIKEN

    SciTech Connect

    Kishida, T.; Ideguchi, E.; Wu, H.Y.

    1996-12-31

    Nuclear high spin states have been the subject of extensive experimental and theoretical studies. For the production of high spin states, fusion reactions are usually used. The orbital angular momentum brought in the reaction is changed into the nuclear spin of the compound nucleus. However, the maximum induced angular momentum is limited in this mechanism by the maximum impact parameter of the fusion reaction and by the competition with fission reactions. It is, therefore, difficult to populate very high spin states, and as a result, large {gamma}-detector arrays have been developed in order to detect subtle signals from such very high spin states. The use of high spin isomers in the fusion reactions can break this limitation because the high spin isomers have their intrinsic angular momentum, which can bring the additional angular momentum without increasing the excitation energy. There are two methods to use the high spin isomers for secondary reactions: the use of the high spin isomers as a target and that as a beam. A high spin isomer target has already been developed and used for several experiments. But this method has an inevitable shortcoming that only {open_quotes}long-lived{close_quotes} isomers can be used for a target: {sup 178}Hf{sup m2} (16{sup +}) with a half-life of 31 years in the present case. By developing a high spin isomer beam, the authors can utilize various short-lived isomers with a short half-life around 1 {mu}s. The high spin isomer beam line of RIKEN Accelerator Facility is a unique apparatus in the world which provides a high spin isomer as a secondary beam. The combination of fusion-evaporation reaction and inverse kinematics are used to produce high spin isomer beams; in particular, the adoption of `inverse kinematics` is essential to use short-lived isomers as a beam.

  13. Synthesis and Reactivity of Four- and Five-Coordinate Low-Spin Cobalt(II) PCP Pincer Complexes and Some Nickel(II) Analogues.

    PubMed

    Murugesan, Sathiyamoorthy; Stöger, Berthold; Carvalho, Maria Deus; Ferreira, Liliana P; Pittenauer, Ernst; Allmaier, Günter; Veiros, Luis F; Kirchner, Karl

    2014-11-10

    Anhydrous CoCl2 or [NiCl2(DME)] reacts with the ligand PCP(Me)-iPr (1) in the presence of nBuLi to afford the 15e and 16e square planar complexes [Co(PCP(Me)-iPr)Cl] (2) and [Ni(PCP(Me)-iPr)Cl] (3), respectively. Complex 2 is a paramagnetic d(7) low-spin complex, which is a useful precursor for a series of Co(I), Co(II), and Co(III) PCP complexes. Complex 2 reacts readily with CO and pyridine to afford the five-coordinate square-pyramidal 17e complexes [Co(PCP(Me)-iPr)(CO)Cl] (4) and [Co(PCP(Me)-iPr)(py)Cl] (5), respectively, while in the presence of Ag(+) and CO the cationic complex [Co(PCP(Me)-iPr)(CO)2](+) (6) is afforded. The effective magnetic moments μeff of all Co(II) complexes were derived from the temperature dependence of the inverse molar magnetic susceptibility by SQUID measurements and are in the range 1.9 to 2.4 μB. This is consistent with a d(7) low-spin configuration with some degree of spin-orbit coupling. Oxidation of 2 with CuCl2 affords the paramagnetic Co(III) PCP complex [Co(PCP(Me)-iPr)Cl2] (7), while the synthesis of the diamagnetic Co(I) complex [Co(PCP(Me)-iPr)(CO)2] (8) was achieved by stirring 2 in toluene with KC8 in the presence of CO. Finally, the cationic 16e Ni(II) PCP complex [Ni(PCP(Me)-iPr)(CO)](+) (10) was obtained by reacting complex 3 with 1 equiv of AgSbF6 in the presence of CO. The reactivity of CO addition to Co(I), Co(II), and Ni(II) PCP square planar complexes of the type [M(PCP(Me)-iPr)(CO)] (n) (n = +1, 0) was investigated by DFT calculations, showing that formation of the Co species, 6 and 8, is thermodynamically favorable, while Ni(II) maintains the 16e configuration since CO addition is unfavorable in this case. X-ray structures of most complexes are provided and discussed. A structural feature of interest is that the apical CO ligand in 4 deviates significantly from linearity, with a Co-C-O angle of 170.0(1)°. The DFT-calculated value is 172°, clearly showing that this is not a packing but an electronic effect.

  14. High-Spin Cobalt Hydrides for Catalysis

    SciTech Connect

    Holland, Patrick L.

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  15. Spin structure in high energy processes: Proceedings

    SciTech Connect

    DePorcel, L.; Dunwoodie, C.

    1994-12-01

    This report contains papers as the following topics: Spin, Mass, and Symmetry; physics with polarized Z{sup 0}s; spin and precision electroweak physics; polarized electron sources; polarization phenomena in quantum chromodynamics; polarized lepton-nucleon scattering; polarized targets in high energy physics; spin dynamics in storage rings and linear accelerators; spin formalism and applications to new physics searches; precision electroweak physics at LEP; recent results on heavy flavor physics from LEP experiments using 1990--1992 data; precise measurement of the left-right cross section asymmetry in Z boson production by electron-positron collisions; preliminary results on heavy flavor physics at SLD; QCD tests with SLD and polarized beams; recent results from TRISTAN at KEK; recent B physics results from CLEO; searching for the H dibaryon at Brookhaven; recent results from the compton observatory; the spin structure of the deuteron; spin structure of the neutron ({sup 3}HE) and the Bjoerken sum rule; a consumer`s guide to lattice QCD results; top ten models constrained by b {yields} sy; a review of the Fermilab fixed target program; results from the D0 experiment; results from CDF at FNAL; quantum-mechanical suppression of bremsstrahlung; report from the ZEUS collaboration at HERA; physics from the first year of H1 at HERA, and hard diffraction. These papers have been cataloged separately elsewhere.

  16. Synthesis, crystal structure and magnetic property of a new cobalt(II) vanadate

    SciTech Connect

    Zhang, Su-Yun; Guo, Wen-Bin; Yang, Ming; Tang, Ying-Ying; Wang, Nan-Nan; Huang, Rong-Rong; Cui, Mei-Yan; He, Zhang-Zhen

    2015-05-15

    A new cobalt(II) vanadate has been synthesized by hydrothermal reaction. It exhibits 3D cobalt(II) oxide architecture with Co{sub 12} member ring (MR) and Co{sub 6} MR tunnels along c-axis. V(2)O{sub 4} tetrahedra are located at the center of Co{sub 6}-MR tunnels whereas V(1)O{sub 4} tetrahedra and ‘isolated’ 1D Co(1)O{sub 6} octahedral chains are located at the Co{sub 12}-MR tunnels. The 3D cobalt(II) oxide architecture is constructed on irregular ladder chains formed by edge- and face-sharing of Co(2)O{sub 6} octahedra whereas the ‘isolated’ 1D Co(1)O{sub 6} octahedral chain in the tunnels are formed by face-sharing of Co(1)O{sub 6} octahedra. Magnetic property is investigated by means of magnetic susceptibility, magnetization and heat capacity measurement. Magnetic susceptibility and heat capacity measurement indicate a typical long-range spin-canting antiferromagnetic ordering below ~71 K; metamagnetic behavior was detected in the isothermal magnetization measurement at 2 K. - Graphical abstract: A cobalt(II) vanadate, Co{sub 7}V{sub 4}O{sub 16}(OH){sub 2}(H{sub 2}O) has been synthesized and structurally characterized. It exhibits antiferromagnetic interaction with weak spin-canting below ~71 K; metamagnetic behavior was detected in isothermal magnetization at 2 K. - Highlights: • Hydrothermal reaction of CoCl{sub 2}·6H{sub 2}O and Na{sub 3}VO{sub 4} yielded a new cobalt(||) vanadate. • It shows novel structure since its large Co/V ratio. • It shows long-range spin-canting antiferromagnetic ordering below ~71 K. • Metamagnetic behavior was detected in the isothermal magnetization at 2 K.

  17. High-Spin Structure of 102Ru

    SciTech Connect

    Sohler, D.; Timar, J.; Molnar, J.; Algora, A.; Dombradi, Zs.; Krasznahorkay, A.; Zolnai, L.; Rainovski, G.; Joshi, P.; Wadsworth, R.; Jenkins, D.G.; Raddon, P.M.; Simons, A.J.; Wilkinson, A.R.; Starosta, K.; Fossan, D.B.; Bednarczyk, P.; Curien, D.; Duchene, G.; Gizon, A.

    2005-11-21

    High-spin states in the nucleus 102Ru have been studied through the 96Zr(13C,{alpha}3n) reaction using the EUROBALL IV {gamma}-ray spectrometer accompanied by the DIAMANT array for the detection of charged particles. All previously known bands have been extended to higher spins and additional bands have been found. Comparing the experimental Routhians and aligned angular momenta to the predictions of Woods-Saxon TRS calculations, vh11/2(d5/2,g7/2) configurations have been assigned to the observed negative-parity bands.

  18. High spin states in {sup 139}Pm

    SciTech Connect

    Dhal, A.; Sinha, R. K.; Chaturvedi, L.; Agarwal, P.; Kumar, S.; Jain, A. K.; Kumar, R.; Govil, I. M.; Mukhopadhyay, S.; Chakraborty, A.; Krishichayan; Ray, S.; Ghugre, S. S.; Sinha, A. K.; Kumar, R.; Singh, R. P.; Muralithar, S.; Bhowmik, R. K.; Pancholi, S. C.; Gupta, J. B.

    2009-07-15

    The odd mass nucleus {sup 139}Pm has been studied to high spins through the {sup 116}Cd({sup 27}Al,4n){sup 139}Pm reaction at an incident beam energy of 120 MeV. The de-exciting {gamma}-rays were detected using an array of 12 Compton suppressed Ge detectors. A total of 46 new levels have been proposed in the present work as a result of the observation of 60 new {gamma}-rays. Four new bands including a {delta}J=1 sequence have been identified and all the earlier reported bands, other than the yrast band, have been extended to higher spins and excitation energy. The spin assignments for most of the newly reported levels have been made using the observed coincidence angular anisotropy. Tilted axis cranking calculations support the interpretation of two of the observed magnetic dipole sequences as examples of magnetic rotational bands.

  19. Development of a high altitude Spin Parachute

    NASA Technical Reports Server (NTRS)

    Silbert, M. N.

    1981-01-01

    A specially configured 16.6 foot (5.1 meter) Disc Gap Band (DGB) Spin Parachute has been designed, developed, integrated with a sounding rocket, and qualified by flight testing. Design requirements include (1) stable parachute should successfully deploy in the altitude region of 260,000 feet (80 kilometers) from a Super Arcas launch vehicle; (2) after deployment, parachute and payload spin rate should be greater than three rpm; (3) four electric field sensors should be mounted on parachute shroud lines and have provisions to be electrically connected to the suspended payload; and (4) time above 100,000 feet (30 kilometers) should exceed five minutes. The successful meeting of these requirements provided the first known high-altitude deployment of a Spin Parachute.

  20. High spin states of [sup 84]Sr

    SciTech Connect

    Garcia Bermudez, G.; Baktash, C.; Abenante, V.; Griffin, H.C.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Sarantites, D.G.; Semkow, T.M.; Stracener, D.W.; Virtanen, A. Joint Institute for Heavy-Ion Research, Oak Ridge, Tennessee 37831 Departamento de Fisica, Comision Nacional de Energia Atomica, 1429 Buenos Aires Department of Chemistry, Washington University, Saint Louis, Missouri 63130 Department of chemistry, University of Michigan, Ann Arbor, Michigan 48104 )

    1994-06-01

    High spin states of [sup 84]Sr nucleus excited through the [sup 52]Cr([sup 36]S,2[ital p]2[ital n]) reaction at 130 MeV energy were studied utilizing the Oak Ridge Compton-Suppression Spectrometer System. The level scheme has been extended up to probably [ital I][sup [pi

  1. Pairing correlations in high-spin isomers

    SciTech Connect

    Odahara, A.; Gono, Y.; Fukuchi, T.; Wakabayashi, Y.; Sagawa, H.; Satula, W.; Nazarewicz, W.

    2005-12-15

    High-spin isomers with J{sup {pi}}=49/2{sup +} and 27{sup +} have been systematically observed in a number of N=83 isotones with 60{<=}Z{<=}67 at excitation energies {approx}9 MeV. Based on experimental excitation energies, an odd-even binding energy staggering has been extracted for the first time for these multi-quasiparticle states. Surprisingly, the magnitude of the odd-even effect in high-spin isomers turned out to be very close to that in ground states, thus challenging conventional wisdom that pairing correlations are reduced in highly excited states. Theoretical analysis based on mean-field theory explains the observed proton number dependence of the odd-even effect as a manifestation of strong pairing correlations in the highly excited states. Mean-field effects and the proton-neutron residual interaction on the odd-even staggering are also examined.

  2. High-spin states in ^88Kr

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Lisetskiy, A. F.; Cizewski, J. A.; Krücken, R.; Clark, R. M.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Becker, J. A.; Younes, W.

    2007-10-01

    High-spin states in ^88Kr have been studied following the fission of the ^226Th compound nucleus formed in a fusion-evaporation reaction (^18O at 91 MeV on ^208Pb). The Gammasphere array was used to detect γ-ray coincidences. High-spin states up to spin (14^+) and ˜8 MeV excitation energy have been established. The level scheme reported for ^88Kr in the spontaneous fission of ^248Cm [1] has been enriched and extended to higher spin and excitation energies. Differences between the level scheme reported in [1] and that obtained in the present work will be discussed. The observed experimental states are also compared with theoretical shell-model and interacting-boson-model-2 calculations. This work has been supported by the U.S. Department of Energy under Contracts No. DE-AC52-06NA25396 (LANL), W-7405-ENG-48 (LLNL) and AC03-76SF00098 (LBNL) and by the National Science Foundation (Rutgers). [1] T. Rzaca-Urban et al., Eur. Phys. J. A 9, 165 (2000).

  3. Cobalt(II) chloride adducts with acetonitrile, propan-2-ol and tetrahydrofuran: considerations on nuclearity, reactivity and synthetic applications.

    PubMed

    Stinghen, Danilo; Rüdiger, André Luis; Giese, Siddhartha O K; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2017-02-01

    High-spin cobalt(II) complexes are considered useful building blocks for the synthesis of single-molecule magnets (SMM) because of their intrinsic magnetic anisotropy. In this work, three new cobalt(II) chloride adducts with labile ligands have been synthesized from anhydrous CoCl2, to be subsequently employed as starting materials for heterobimetallic compounds. The products were characterized by elemental, spectroscopic (EPR and FT-IR) and single-crystal X-ray diffraction analyses. trans-Tetrakis(acetonitrile-κN)bis(tetrahydrofuran-κO)cobalt(II) bis[(acetonitrile-κN)trichloridocobaltate(II)], [Co(C2H3N)4(C4H8O)2][CoCl3(C2H3N)]2, (1), comprises mononuclear ions and contains both acetonitrile and tetrahydrofuran (thf) ligands, The coordination polymer catena-poly[[tetrakis(propan-2-ol-κO)cobalt(II)]-μ-chlorido-[dichloridocobalt(II)]-μ-chlorido], [Co2Cl4(C3H8O)4], (2'), was prepared by direct reaction between anhydrous CoCl2 and propan-2-ol in an attempt to rationalize the formation of the CoCl2-alcohol adduct (2), probably CoCl2(HO(i)Pr)m. The binuclear complex di-μ-chlorido-1:2κ(4)Cl:Cl-dichlorido-2κ(2)Cl-tetrakis(tetrahydrofuran-1κO)dicobalt(II), [Co2Cl4(C4H8O)4], (3), was obtained from (2) after recrystallization from tetrahydrofuran. All three products present cobalt(II) centres in both octahedral and tetrahedral environments, the former usually less distorted than the latter, regardless of the nature of the neutral ligand. Product (2') is stabilized by an intramolecular hydrogen-bond network that appears to favour a trans arrangement of the chloride ligands in the octahedral moiety; this differs from the cis disposition found in (3). The expected easy displacement of the bound solvent molecules from the metal coordination sphere makes the three compounds good candidates for suitable starting materials in a number of synthetic applications.

  4. Future directions for high-spin studies

    SciTech Connect

    Stephens, F.S.

    1982-11-01

    Some future directions for experimental high-spin studies are discussed, concentrating mainly on the region above I -- 30h, where the ..gamma..-ray spectra are currently unresolvable. The 4..pi.. NaI balls offer a means to exploit the temperature effects recently shown to exist in such spectra. Large arrays of Compton-suppressed Ge detectors, on the other and, lead to higher effective resolution as it becomes possible to study triple and quadruple coincident events.

  5. What Controls the Sign and Magnitude of Magnetic Anisotropy in Tetrahedral Cobalt(II) Single-Ion Magnets?

    PubMed

    Vaidya, Shefali; Tewary, Subrata; Singh, Saurabh Kumar; Langley, Stuart K; Murray, Keith S; Lan, Yanhua; Wernsdorfer, Wolfgang; Rajaraman, Gopalan; Shanmugam, Maheswaran

    2016-10-03

    A family of mononuclear tetrahedral cobalt(II) thiourea complexes, [Co(L1)4](NO3)2 (1) and [Co(Lx)4](ClO4)2 where x = 2 (2), 3 (3), 4 (4) (where L1 = thiourea, L2 = 1,3-dibutylthiourea, L3 = 1,3-phenylethylthiourea, and L4 = 1,1,3,3-tetramethylthiourea), has been synthesized using a rationally designed synthetic approach, with the aim of stabilizing an Ising-type magnetic anisotropy (-D). On the basis of direct-current, alternating-current, and hysteresis magnetic measurements and theoretical calculations, we have identified the factors that govern the sign and magnitude of D and ultimately the ability to design a single-ion magnet for a tetrahedral cobalt(II) ion. To better understand the magnetization relaxation dynamics, particularly for complexes 1 and 2, dilution experiments were performed using their diamagnetic analogues, which are characterized by single-crystal X-ray diffraction with the general molecular formulas of [Zn(L1)4](NO3)2 (5) and [Zn(L2)4](ClO4)2 (6). Interestingly, intermolecular interactions are shown to play a role in quenching the quantum tunneling of magnetization in zero field, as evidenced in the hysteresis loop of 1. Complex 2 exhibits the largest Ueff value of 62 cm(-1) and reveals open hysteresis loops below 4 K. Furthermore, the influence of the hyperfine interaction on the magnetization relaxation dynamics is witnessed in the hysteresis loops, allowing us to determine the electron/nuclear spin S(Co) = (3)/2/I(Co) = (7)/2 hyperfine coupling constant of 550 MHz, a method ideally suited to determine the hyperfine coupling constant of highly anisotropic metal ions stabilized with large D value, which are otherwise hard to determine by conventional methods such as electron paramagnetic resonance.

  6. High-spin structure of 134Xe

    NASA Astrophysics Data System (ADS)

    Vogt, A.; Birkenbach, B.; Reiter, P.; Blazhev, A.; Siciliano, M.; Valiente-Dobón, J. J.; Wheldon, C.; Bazzacco, D.; Bowry, M.; Bracco, A.; Bruyneel, B.; Chakrawarthy, R. S.; Chapman, R.; Cline, D.; Corradi, L.; Crespi, F. C. L.; Cromaz, M.; de Angelis, G.; Eberth, J.; Fallon, P.; Farnea, E.; Fioretto, E.; Freeman, S. J.; Gadea, A.; Geibel, K.; Gelletly, W.; Gengelbach, A.; Giaz, A.; Görgen, A.; Gottardo, A.; Hayes, A. B.; Hess, H.; Hua, H.; John, P. R.; Jolie, J.; Jungclaus, A.; Korten, W.; Lee, I. Y.; Leoni, S.; Liang, X.; Lunardi, S.; Macchiavelli, A. O.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatović, T.; Montagnoli, G.; Montanari, D.; Napoli, D.; Pearson, C. J.; Pellegri, L.; Podolyák, Zs.; Pollarolo, G.; Pullia, A.; Radeck, F.; Recchia, F.; Regan, P. H.; Şahin, E.; Scarlassara, F.; Sletten, G.; Smith, J. F.; Söderström, P.-A.; Stefanini, A. M.; Steinbach, T.; Stezowski, O.; Szilner, S.; Szpak, B.; Teng, R.; Ur, C.; Vandone, V.; Ward, D.; Warner, D. D.; Wiens, A.; Wu, C. Y.

    2016-05-01

    Detailed spectroscopic information on the N ˜82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in 134Xe is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in 238U+ 136Xe and 208Pb+ 136Xe MNT reactions and (ii) as a fission product in the 238U+ 136Xe reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The 198Pt 136Xe MNT reaction was studied with the γ -ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in 134Xe on top of the two long-lived isomers are discovered based on γ γ -coincidence relationships and information on the γ -ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of 134Xe is extended up to an excitation energy of 5.832 MeV with tentative spin-parity assignments up to 16+. Previous assignments of states above the 7- isomer are revised. Latest shell-model calculations employing two different effective interactions reproduce the experimental findings and support the new spin and parity assignments.

  7. Spin Hall magnetoresistance at high temperatures

    SciTech Connect

    Uchida, Ken-ichi; Qiu, Zhiyong; Kikkawa, Takashi; Iguchi, Ryo; Saitoh, Eiji

    2015-02-02

    The temperature dependence of spin Hall magnetoresistance (SMR) in Pt/Y{sub 3}Fe{sub 5}O{sub 12} (YIG) bilayer films has been investigated in a high temperature range from room temperature to near the Curie temperature of YIG. The experimental results show that the magnitude of the magnetoresistance ratio induced by the SMR monotonically decreases with increasing the temperature and almost disappears near the Curie temperature. We found that, near the Curie temperature, the temperature dependence of the SMR in the Pt/YIG film is steeper than that of a magnetization curve of the YIG; the critical exponent of the magnetoresistance ratio is estimated to be 0.9. This critical behavior of the SMR is attributed mainly to the temperature dependence of the spin-mixing conductance at the Pt/YIG interface.

  8. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex

    NASA Astrophysics Data System (ADS)

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng

    2016-04-01

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

  9. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex.

    PubMed

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng

    2016-04-21

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

  10. Fluorescence reaction of 5-(p-methoxyphenylazo)-8-(p-tolylsulfonamido)quinoline with cobalt(II) and its analytical application

    SciTech Connect

    Zeng Zuotao ) Xu Qiheng )

    1992-08-01

    5-(p-Methoxyphenylazo)-8-(p-tolylsulfonamido)quinoline(MTAQ) has been synthesized. The product was checked by IR, thermogravimetry, NMR and elemental analysis. A highly sensitive spectrofluorimetric method has been developed for the determination of cobalt(II) based on the formation of a complex with MTAQ in slightly basic medium aqueous solution and in the presence of nonionic surfactant, tween-80. The complex shows two excitation maxima at 304 nm and 338 nm, its emission maximum is centered at 402nm. The fluorescence intensity is proportional to cobalt(II) concentration in the range of 0-85 ppb. The method has good selectivity and has been applied to the direct fluorimetric determination of trace cobalt(II) in pig's liver, Dianchi shrimp and celery.

  11. High field electron spin resonance experiments on spin - Peierls compounds

    NASA Astrophysics Data System (ADS)

    Palme, W.; Schmidt, S.; Lüthi, B.; Boucher, J. P.; Weiden, M.; Hauptmann, R.; Geibel, C.; Revcolevschi, A.; Dhalenne, G.

    1998-05-01

    The spin-Peierls (SP) transition is still one of the most challenging effects in quasi-one-dimensional magnetism. A few years ago the first inorganic spin-Peierls compound CuGeO 3 with TSP=14.3 K was discovered, and recently α‧-NaV 2O 5 was found to be another inorganic SP system with the highest transition temperature so far observed: TSP=35 K. Electron spin resonance (ESR) is the only direct way to probe electron spin dynamics in magnetic fields higher than 12 T, where a transition to an incommensurate magnetic phase can occur. We present ESR results on single crystals of pure and Si-doped CuGeO 3 and pure α‧-NaV 2O 5. Our experiments were done in a wide frequency range 35-440 GHz in magnetic fields up to 16 T, covering a large temperature range 1.5-100 K. The temperature dependence of the ESR absorption in the D-phase in α‧-NaV 2O 5 points to transitions among triplet states, which are separated from the singlet ground state by an energy gap Δ≈85 K for T →0 . In contrast to χ( T) the ESR absorption does not stay finite for T →0 . In the incommensurate phase of slightly Si-doped CuGeO 3 (0.2% Si) ESR signals were observed, but their behaviour is much different from the ones in the pure compound.

  12. High spins in gamma-soft nuclei

    SciTech Connect

    Leander, G.A.; Frauendorf, S.; May, F.R.

    1982-01-01

    Nuclei which are soft with respect to the ..gamma.. shape degree of freedom are expected to have many different structures coexisting in the near-yrast regime. In particular, the lowest rotational quasi-particle in a high-j shell exerts a strong polarizing effect on ..gamma... The ..gamma.. to which it drives is found to vary smoothly over a 180/sup 0/ range as the position of the Fermi level varies. This simple rule is seen to have a direct connection with the energy staggering of alternate spin states in rotational bands. A diagram is presented which provides a general theoretical reference for experimental tests of the relation between ..gamma.., spin staggering, configuration, and nucleon number. In a quasicontinuum spectrum, the coexistence of different structures are expected to make several unrelated features appear within any one slice of sum energy and multiplicity. However, it is also seen that the in-band moment of inertia may be similar for many bands of different ..gamma...

  13. High resolution spin- and angle-resolved photoelectron spectroscopy for 3D spin vectorial analysis

    NASA Astrophysics Data System (ADS)

    Okuda, Taichi; Miyamoto, Koji; Kimura, Akio; Namatame, Hirofumi; Taniguchi, Masaki

    2013-03-01

    Spin- and angle-resolved photoelectron spectroscopy (SARPES) is the excellent tool which can directly observe the band structure of crystals with separating spin-up and -down states. Recent findings of new class of materials possessing strong spin orbit interaction such as Rashba spin splitting systems or topological insulators stimulate to develop new SARPES apparatuses and many sophisticated techniques have been reported recently. Here we report our newly developed a SARPES apparatus for spin vectorial analysis with high precision at Hiroshima Synchrotron Radiation Center. Highly efficient spin polarimeter utilizing very low energy electron diffraction (VLEED) makes high resolution (ΔE < 10 meV, Δθ ~ +/- 0.2 °) compatible with the SARPES measurement. By placing two VLEED spin detectors orthogonally we have realized the polarization measurement of all spin components (x, y and z) with the high resolution. Some examples of the three-dimensional spin observation will be presented. This work is supported by KAKENHI (23244066), Grant-in-Aid for Scientific Research (A) of Japan Society for the Promotion of Science.

  14. High spin states in 78Sr

    NASA Astrophysics Data System (ADS)

    Gross, C. J.; Heese, J.; Lieb, K. P.; Lister, C. J.; Varley, B. J.; Chishti, A. A.; McNeill, J. H.; Gelletly, W.

    1989-05-01

    78Sr was produced in the reaction 58Ni(24Mg, 2p2n) with a relative cross section of less than 2.5% of the total fusion cross section at 110 MeV, but high spin states up to 16ħ were firmly identified. Fifteen neutron detectors and fifteen Compton suppressed Ge detectors were used in a large solid angle arrangement. 2nγγ and nγγ coincidences were recorded. A small irregularity in the dynamic moment of inertia J(2)/ħ2 is evidence for a strongly mixed band crossing at ħω~=0.55 MeV in agreement with what is observed in 80,82Sr.

  15. Nitrous oxide activation by a cobalt(ii) complex for aldehyde oxidation under mild conditions.

    PubMed

    Corona, Teresa; Company, Anna

    2016-10-07

    Nitrous oxide (N2O) is a waste gas produced in many industrial processes with an important environmental impact. Thus, its application as an oxidant is highly desirable because it produces innocuous N2 as a by-product. In this work we report a new cobalt(ii) complex that reacts with N2O under mild conditions and the catalytic application of this system to carry out the oxidation of aldehydes.

  16. High-Tc spin superfluidity in antiferromagnets.

    PubMed

    Bunkov, Yu M; Alakshin, E M; Gazizulin, R R; Klochkov, A V; Kuzmin, V V; L'vov, V S; Tagirov, M S

    2012-04-27

    We report the observation of the unusual behavior of induction decay signals in antiferromagnetic monocrystals with Suhl-Nakamura interactions. The signals show the formation of the Bose-Einstein condensation (BEC) of magnons and the existence of spin supercurrent, in complete analogy with the spin superfluidity in the superfluid (3)He and the atomic BEC of quantum gases. In the experiments described here, the temperature of the magnon BEC is a thousand times larger than in the superfluid (3)He. It opens a possibility to apply the spin supercurrent for various magnetic spintronics applications.

  17. High-spin states in 127I

    NASA Astrophysics Data System (ADS)

    Ding, B.; Zhang, Y. H.; Zhou, X. H.; Dong, G. X.; Xu, F. R.; Liu, M. L.; Li, G. S.; Zhang, N. T.; Wang, H. X.; Zhou, H. B.; Ma, Y. J.; Sasakiz, Y.; Yamada, K.; Ohshima, H.; Yokose, S.; Ishizuka, M.; Komatsubara, T.; Furuno, K.

    2012-04-01

    In-beam γ spectroscopy of the stable nucleus 127I has been studied experimentally using the 124Sn(7Li, 4nγ)127I reaction at a beam energy of 32 MeV. The high-spin level scheme of 127I is extended significantly. Negative-parity levels built on the 11/2-, πh11/2 particle state are observed up to (35/2-) and described as a decoupled band, extending our knowledge of decoupled structures to the most neutron-rich stable iodine isotope. Two ΔI=2 yrast positive-parity sequences are proposed to be associated with the πg7/2 configuration due to observations of several strong interband transitions, and two weakly populated ΔI=2 positive-parity bands are newly identified and interpreted as arising mainly from the πd5/2 configuration. Three-quasiparticle configurations are assigned to the Iπ=15/2+ and 23/2+ states according to the existing knowledge in neighboring nuclei; irregular noncollective and regular collective excitations built on these two (15/2+ and 23/2+) states are observed to coexist at similar energies. The observed three-quasiparticle band structures are further interpreted with the aid of configuration-constrained potential energy surface calculations.

  18. Production dynamics and high p/sub T/ spin effects

    SciTech Connect

    Soffer, J.

    1988-08-01

    We will emphasize the importance of spin for our understanding of production dynamics at high p/sub T/. Within the framework of perturbative QCD several predictions for interesting spin observables are presented for various reactions. They are crucial tests accessible to existing or future experimental programs. 17 refs., 10 figs.

  19. High-spin states in the 94Nb nucleus

    NASA Astrophysics Data System (ADS)

    Mărginean, N.; Bucurescu, D.; Căta-Danil, Ghe.; Căta-Danil, I.; Ivaşcu, M.; Ur, C. A.

    2000-09-01

    High-spin states have been studied for the first time in the 94Nb nucleus with the reaction 82Se(19F,α3nγ) at 68 MeV. A cascade of transitions has been observed, based on the (6)+ ground state and extending up to 6.5 MeV excitation and spin of about 19.

  20. High Spin Isomers and Super Heavy Elements (SHE) Synthesis

    SciTech Connect

    Popescu, Domitian G.

    2010-04-30

    To get closer to the SHE-Island the new radioactive beams are proposed for future fusion reaction. We suggest something different: to use the advantage of High Spin Isomer States, by tacking into account the importance of the G (spin-isospin cupling) suggested by Ripka 1.

  1. High-spin binary black hole mergers

    NASA Astrophysics Data System (ADS)

    Marronetti, Pedro; Tichy, Wolfgang; Brügmann, Bernd; González, Jose; Sperhake, Ulrich

    2008-03-01

    We study identical mass black hole binaries with spins perpendicular to the binary’s orbital plane. These binaries have individual spins ranging from s/m2=-0.90 to 0.90, (s1=s2 in all cases) which is near the limit possible with standard Bowen-York puncture initial data. The extreme cases correspond to the largest initial spin simulations to date. Our results expand the parameter space covered by Rezzolla et al., and when combining both data sets, we obtain estimations for the minimum and maximum values for the intrinsic angular momenta of the remnant of binary black hole mergers of J/M2=0.341±0.004 and 0.951±0.004, respectively. Note, however, that these values are reached through extrapolation to the singular cases |s1|=|s2|=1 and thus remain as estimates until full-fledged numerical simulations provide confirmation.

  2. High-spin binary black hole mergers

    NASA Astrophysics Data System (ADS)

    Marronetti, Pedro; Tichy, Wolfgang; Brügmann, Bernd; Sperhake, Ulrich; González, José

    2008-04-01

    We study identical mass black hole binaries with spins perpendicular to the binary's orbital plane. These binaries have individual spins ranging from s/m^2=-0.90 to 0.90, (s1= s2 in all cases) which is near the limit possible with standard Bowen-York puncture initial data. The extreme cases correspond to the largest initial spin simulations to date. Our results expand the parameter space covered by Rezzolla et al. and, when combining both data sets, we obtain estimations for the minimum and maximum values for the intrinsic angular momenta of the remnant of binary black hole mergers of J/M^2=0.341(4) and 0.951(4) respectively.

  3. Cobalt(II), nickel(II) and copper(II) complexes of a hexadentate pyridine amide ligand. Effect of donor atom (ether vs. thioether) on coordination geometry, spin-state of cobalt and M(III)-M(II) redox potential.

    PubMed

    Pandey, Sharmila; Das, Partha Pratim; Singh, Akhilesh Kumar; Mukherjee, Rabindranath

    2011-10-28

    Using an acyclic hexadentate pyridine amide ligand, containing a -OCH(2)CH(2)O- spacer between two pyridine-2-carboxamide units (1,4-bis[o-(pyrydine-2-carboxamidophenyl)]-1,4-dioxabutane (H(2)L(9)), in its deprotonated form), four new complexes, [Co(II)(L(9))] (1) and its one-electron oxidized counterpart [Co(III)(L(9))][NO(3)]·2H(2)O (2), [Ni(II)(L(9))] (3) and [Cu(II)(L(9))] (4), have been synthesized. Structural analyses revealed that the Co(II) centre in 1 and the Ni(II) centre in 3 are six-coordinate, utilizing all the available donor sites and the Cu(II) centre in 4 is effectively five-coordinated (one of the ether O atoms does not participate in coordination). The structural parameters associated with the change in the metal coordination environment have been compared with corresponding complexes of thioether-containing hexadentate ligands. The μ(eff) values at 298 K of 1-4 correspond to S = 3/2, S = 0, S = 1 and S = 1/2, respectively. Absorption spectra for all the complexes have been investigated. EPR spectral properties of the copper(II) complex 4 have been investigated, simulated and analyzed. Cyclic voltammetric experiments in CH(2)Cl(2) reveal quasireversible Co(III)-Co(II), Ni(III)-Ni(II) and Cu(II)-Cu(I) redox processes. In going from ether O to thioether S coordination, the effect of the metal coordination environment on the redox potential values of Co(III)-Co(II) (here the effect of spin-state as well), Ni(III)-Ni(II) and Cu(II)-Cu(I) processes have been systematically analyzed.

  4. Toward high-frequency operation of spin lasers

    NASA Astrophysics Data System (ADS)

    Junior, Paulo E. Faria; Xu, Gaofeng; Lee, Jeongsu; Gerhardt, Nils C.; Sipahi, Guilherme M.; Žutić, Igor

    2015-08-01

    Injecting spin-polarized carriers into semiconductor lasers provides important opportunities to extend what is known about spintronic devices, as well as to overcome many limitations of conventional (spin-unpolarized) lasers. By developing a microscopic model of spin-dependent optical gain derived from an accurate electronic structure in a quantum-well-based laser, we study how its operation properties can be modified by spin-polarized carriers, carrier density, and resonant cavity design. We reveal that by applying a uniaxial strain, it is possible to attain a large birefringence. While such birefringence is viewed as detrimental in conventional lasers, it could enable fast polarization oscillations of the emitted light in spin lasers, which can be exploited for optical communication and high-performance interconnects. The resulting oscillation frequency (>200 GHz) would significantly exceed the frequency range possible in conventional lasers.

  5. Excellent spin transport in spin valves based on the conjugated polymer with high carrier mobility

    PubMed Central

    Li, Feng; Li, Tian; Chen, Feng; Zhang, Fapei

    2015-01-01

    Organic semiconductors (OSCs) are characteristic of long spin-relaxation lifetime due to weak spin-orbit interaction and hyperfine interaction. However, short spin diffusion length and weak magnetoresistance (MR) effect at room temperature (RT) was commonly found on spin valves (SVs) using an organic spacer, which should be correlated with low carrier mobility of the OSCs. Here, N-type semiconducting polymer P(NDI2OD-T2) with high carrier mobility is employed as the spacer in the SV devices. Exceedingly high MR ratio of 90.0% at 4.2 K and of 6.8% at RT are achieved, respectively, via improving the interface structure between the polymer interlayer and top cobalt electrode as well as optimal annealing of manganite bottom electrode. Furthermore, we observe spin dependent transport through the polymeric interlayer and a large spin diffusion length with a weak temperature dependence. The results indicate that this polymer material can be used as a good medium for spintronic devices. PMID:25797862

  6. Magnetic circular dichroism of symmetry and spin forbidden transitions of high-spin metal ions

    NASA Astrophysics Data System (ADS)

    Oganesyan, Vasily S.; Thomson, Andrew J.

    2000-09-01

    Recently we have developed a general method of analyzing magnetic circular dichroism (MCD) spectra and magnetization curves of high-spin metal ions for spin-allowed transitions [Oganesyan et al., J. Chem. Phys. 110, 762 (1999)]. In the present article this approach is extended to cover the cases of spin- and symmetry-forbidden transitions. At high ligand fields many low-energy ligand field transitions become spin-forbidden. Extraction of information content about the electronic structure of the ground state can be obtained through the analysis and correlation of the positions, signs, and intensities of the MCD bands and magnetization curves of these transitions. The casting of the theory in terms of the irreducible tensor method allows full advantage to be taken of any symmetry elements and simplifies multielectron calculations. The theory is valid over the entire range of magnetic field strength and, therefore, allows the information content of spectra over the full field and temperature range to be exploited. The method is applied to the analysis of the recorded MCD spectra and magnetization curves of the lowest energy spin-forbidden ligand field transitions of pseudo-tetrahedral high-spin Fe(III), S=5/2, in the protein rubredoxin from Methanobacterium thermoautotrophicum (strain Marburg). The predicted signs, intensities, and magnetization curves for these transitions are in excellent agreement with experimental data. We also show that when the anisotropy of the ground state is larger than the Zeeman splitting the MCD of both spin-forbidden and allowed transitions can become comparable in magnitude. Hence caution is needed in order to avoid the misinterpretation of experimental results.

  7. High-spin states in the 96Tc nucleus

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Căta-Danil, Gh.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Rusu, C.; Stroe, L.; Ur, C. A.; Gizon, A.; Gizon, J.; Nyakó, B.; Timár, J.; Zolnai, L.; Boston, A. J.; Joss, D. T.; Paul, E. S.; Semple, A. T.; Parry, C. M.

    High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10 MeV and spin 21-22?.

  8. High-spin states in the 97Tc nucleus

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Gadea, A.; Căta-Danil, Ghe.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Rusu, C.; Stroe, L.; Ur, C. A.

    High-spin states in the 97Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction 82Se(19F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2ℎ. The observed level scheme is compared with results of shell model calculations.

  9. High-spin states in 208Rn

    NASA Astrophysics Data System (ADS)

    Triggs, W. J.; Poletti, A. R.; Dracoulis, G. D.; Fahlander, C.; Byrne, A. P.

    1983-03-01

    The yrast decay scheme of 208Rn has been investigated up to spin ≈ 20 h̵ and an excitation energy of ≈ 6 MeV. Several different γ-ray spectroscopic techniques were used to determine the properties of excited states and transitions in the nucleus. Significant changes to the previously established level scheme are proposed, based on the existence of an unobserved 3.1 keV transition. Simple empirical shell-model calculations of level energies aided in the assignment of shell-model configurations to excited states and the decay scheme is discussed in terms of these configurations. The energy level systematics for the even radon isotopes, from A = 206 to 212 are discussed, as are core polarization effects in the even radon isotopes ( A = 204 to 210) and polonium isotopes ( A = 202-208).

  10. Triaxiality and Exotic Rotations at High Spins in 134Ce

    DOE PAGES

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

    2016-06-06

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

  11. Formation and stability of high-spin alkali clusters.

    PubMed

    Schulz, C P; Claas, P; Schumacher, D; Stienkemeier, F

    2004-01-09

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380 mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, van der Waals-like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25 atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  12. Formation and Stability of High-Spin Alkali Clusters

    NASA Astrophysics Data System (ADS)

    Schulz, C. P.; Claas, P.; Schumacher, D.; Stienkemeier, F.

    2004-01-01

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, vanderWaals like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  13. XVI Workshop on High Energy Spin Physics (D-SPIN2015)

    NASA Astrophysics Data System (ADS)

    Lednicky, Richard

    2016-02-01

    Dear Colleagues, Ladies and Gentlemen, on behalf of the Directorate of Joint Institute for Nuclear Research (JINR) it is a pleasure for me to welcome you here to Dubna for the 16th International Workshop on High Energy Spin Physics. It provides an opportunity to present and discuss the news accumulated during last year. Another important feature of this series of workshops has always been the participation of a large number of physicists from the former Soviet Union and Eastern European countries, for which long trips have previously been limited by financial (and earlier also by bureaucratic) reasons. It thus represents an important addition to the series of large International Symposia on spin physics held in even-numbered years in different countries, including the Symposium held in Dubna in 2012. JINR has a long-lasting tradition of experimental and theoretical studies of spin phenomena. The workshops on high energy spin physics started in Dubna in 1981 due to the initiative of L. Lapidus, an outstanding theoretical physicist. Since then, these meetings have been held in Dubna in every odd year and have become regular thanks to Anatoly Vasilievich Efremov, the chairman for many years. Recent years have brought a lot of new experimental results, and above all the discovery and determination of quantum characteristics of the Higgs boson at the Large Hadron Collider.

  14. Applications of highly spin-polarized xenon in NMR

    SciTech Connect

    Long, Henry W.

    1993-09-01

    The main goal of the work presented in this thesis is produce highly spin-polarized xenon to create much greater signal intensities (up to 54,000 times greater) so as to allow studies to be made on systems with low surface area and long spin-lattice relaxation times. The spin-exchange optical pumping technique used to create high nuclear spin polarization is described in detail in chapter two. This technique is initially applied to some multiple-pulse optically detected NMR experiments in low magnetic field (50G) that allow the study of quadrupoler interactions with a surface of only a few square centimeters. In chapter three the apparatus used to allow high field 129Xe NMR studies to be performed with extremely high sensitivity is described and applied to experiments on diamagnetic susceptibility effects in thin (~2000 layers) films of frozen xenon. Preliminary surface investigations of laser polarized 129Xe adsorbed an a variety of materials (salts, molecular crystals, amorphous carbon, graphite) are then discussed. A full detailed study of the surface of a particular polymer, poly(acrylic acid), is presented in chapter four which shows the kind of detailed information that can be obtained from this technique. Along with preliminary results for several similar polymers, a summary is given of xenon studies of a novel ultra-high surface area polymer, poly(triarylcarbinol). Finally in chapter five the exciting possibility of transferring the high spin order of the laser polarized xenon has been used to transfer nuclear spin order to 13CO2 in a xenon matrix and to protons on poly(triarylcarbinol).

  15. Spin resolved bandstructure imaging with a high resolution momentum microscope.

    PubMed

    Tusche, Christian; Krasyuk, Alexander; Kirschner, Jürgen

    2015-12-01

    We present a spin resolving "momentum microscope" for the high resolution imaging of the momentum distribution of photoelectrons. Measurements of the band structure of a Au(111) single crystal surface demonstrate an energy resolution of ΔE=12 meV and a momentum resolution of Δk∥=0.0049 Å(-1), measured at the line-width of the spin-orbit split Shockley surface state. The relative accuracy of the k∥ measurement in the order of 10(-4) Å(-1) reveals a deviation from the ideal two-dimensional free electron gas model of the Shockley surface state, manifested in a threefold radial symmetry. Spin resolution in the full momentum image is obtained by an imaging spin-filter based on low-energy electron diffraction at a Au passivated Ir(100) single crystal. Using working points at 10.5 eV and 11.5 eV scattering energy with a completely reversed asymmetry of ±60% we demonstrate the efficient mapping of the spin texture of the Au(111) surface state.

  16. Spin-bag mechanism of high-temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Schrieffer, J. R.; Wen, X.-G.; Zhang, S.-C.

    1988-01-01

    A new approach to the theory of high-temperature superconductivity is proposed, based on the two-dimensional antiferromagnetic spin correlations observed in these materials over distances large compared to the lattice spacing. The spin ordering produces an electronic pseudogap which is locally suppressed by the addition of a hole. This suppression forms a bag inside which the hole is self-consistently trapped. Two holes are attracted by sharing a common bag. The resulting pairing interaction leads to a superconducting energy gap which is nodeless over the Femri surface.

  17. Gross shell structure at high spin in heavy nuclei

    SciTech Connect

    Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja

    2003-10-07

    Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

  18. Anisotropic Fermi couplings due to large unquenched orbital angular momentum: Q-band (1)H, (14)N, and (11)B ENDOR of bis(trispyrazolylborate) cobalt(II).

    PubMed

    Myers, William K; Scholes, Charles P; Tierney, David L

    2009-08-05

    We report Q-band ENDOR of (1)H, (14)N, and (11)B at the g( parallel) extreme of the EPR spectrum of bis(trispyrazolylborate) cobalt(II) [Co(Tp)(2)] and two structural analogs. This trigonally symmetric, high-spin (hs) S = 3/2 Co(II) complex shows large unquenched ground-state orbital angular momentum, which leads to highly anisotropic electronic g-values (g( parallel) = 8.48, g( perpendicular) = 1.02). The large g-anisotropy is shown to result in large dipolar couplings near g( parallel) and uniquely anisotropic (14)N Fermi couplings, which arise from spin transferred to the nitrogen 2s orbital (2.2%) via antibonding interactions with singly occupied metal d(x(2)-y(2)) and d(z(2)) orbitals. Large, well-resolved (1)H and (11)B dipolar couplings were also observed. Taken in concert with our previous X-band ENDOR measurements at g( perpendicular) ( Myers, W. K.; et al. Inorg. Chem. 2008, 47, 6701-6710 ), the present data allow a detailed analysis of the dipolar hyperfine tensors of two of the four symmetry distinct protons in the parent molecule. In the substituted analogs, changes in hyperfine coupling due to altered metal-proton distances give further evidence of an anisotropic Fermi contact interaction. For the pyrazolyl 3H proton, the data indicate a 0.2 MHz anisotropic contact interaction and approximately 4% transfer of spin away from Co(II). Dipolar coupling also dominates for the axial boron atoms, consistent with their distance from the Co(II) ion, and resolved (11)B quadrupolar coupling showed approximately 30% electronic inequivalence between the B-H and B-C sp(3) bonds. This is the first comprehensive ENDOR study of any hs Co(II) species and lays the foundation for future development.

  19. Ultra-High Spin Spectroscopy In Er Nuclei

    SciTech Connect

    Simpson, J.

    2008-11-11

    The discoveries observed in the ongoing conflict between collective and single-particle nuclear behaviour with increasing angular momentum have driven the field of nuclear spectroscopy for many decades and have given rise to new nuclear phenomena. Recently a new frontier of {gamma} spectroscopy at ultra-high spin has been opened in the rare-earth region with rotational bands that bypass the classic band-terminating states that appear at spin 45({Dirac_h}/2{pi}) in the N 90 Er nuclei. These weakly populated rotational structures have characteristics of triaxial strongly-deformed bands. Such structures have been observed in {sup 157,158,160}Er, following a series of experiments using the Gammasphere spectrometer. These observations herald a return to collective excitations at spins of about 50 to 65({Dirac_h}/2{pi}). This talk reviews the status of the spectroscopy and understanding of the observed structures in these Er and neighbouring nuclei.

  20. High-spin molecular resonances in 12C + 12C

    NASA Astrophysics Data System (ADS)

    Uegaki, E.; Abe, Y.

    2016-05-01

    Resonances observed in the 12C + 12C collisions are studied with a molecular model. At high spins J = 10-18, a stable dinuclear configuration is found to be an equator-equator touching one. Firstly, normal modes have been solved around the equilibrium, with spin J and K-quantum number being specified for rotation of the whole system. Secondly, with respect to large centrifugal energy, Coriolis coupling has been diagonalized among low-lying 11 states of normal-mode excitations, which brings K-mixing. The analyses of decay widths and excitation functions have been done. The molecular ground state exhibits alignments of the orbital angular momentum and the 12C spins, while some of the molecular excited states exhibit disalignments with small widths. Those results are surprisingly in good agreement with the experiments, which will light up a new physical picture of the highspin 12C + 12C resonances.

  1. Lifetimes of high-spin states in {sup 162}Yb

    SciTech Connect

    Carpenter, M.P.; Janssens, R.V.F.; Henry, R.G.

    1995-08-01

    A measurement on lifetimes of high-spin states in the yrast and near-yrast rotational bands in {sup 162}Yb was carried out at ATLAS in order to determine the evolution of collectivity as a function of angular momentum using the {sup 126}Te({sup 40}Ar,4n){sup 162}Yb reaction at 170 MeV. Previous lifetime measurements in the {sup 164,166,168}Yb isotopes showed a dramatic decrease in the transition quadrupole moment Q{sub t} with increasing spin. It was suggested that this decrease in Q{sub t} is brought about by the rotationally-induced deoccupation of high-j configurations, mainly i{sub 13/2} neutrons. If this interpretation is correct, the heavier isotopes should have a larger decrease in Q{sub t} than the lighter mass nuclides due to the position of the Fermi surface in the i{sub 13/2} subshell. Indeed, {sup 160}Yb does not show a clear decrease in Q{sub t} at high spin. No high spin lifetime information exists for {sup 162}Yb, thus this experiment fills the gap of measured Q{sub t}`s in the light Yb series. The data is currently being analyzed.

  2. High spin polarization and spin splitting in equiatomic quaternary CoFeCrAl Heusler alloy

    NASA Astrophysics Data System (ADS)

    Bainsla, Lakhan; Mallick, A. I.; Coelho, A. A.; Nigam, A. K.; Varaprasad, B. S. D. Ch. S.; Takahashi, Y. K.; Alam, Aftab; Suresh, K. G.; Hono, K.

    2015-11-01

    In this paper, we investigate CoFeCrAl alloy by means of ab-initio electronic structure calculations and various experimental techniques. The alloy is found to exist in the B2-type cubic Heusler structure, which is very similar to Y-type (or LiMgPdSn prototype) structure with space group F-43m (#216). Saturation magnetization (MS) of about 2 μB/f.u. is observed at 8 K under ambient pressure, which is in good agreement with the Slater-Pauling rule. MS values are found to be independent of pressure, which is a prerequisite for half-metals. The ab-initio electronic structure calculations predict half-metallicity for the alloy with a spin slitting energy of 0.31 eV. Importantly, this system shows a high current spin polarization value of 0.67±0.02, as deduced from the point contact Andreev reflection measurements. Linear dependence of electrical resistivity with temperature indicates the possibility of reasonably high spin polarization at elevated temperatures (~150 K) as well. All these suggest that CoFeCrAl is a promising material for the spintronic devices.

  3. Observing bulk diamond spin coherence in high-purity nanodiamonds

    NASA Astrophysics Data System (ADS)

    Knowles, Helena S.; Kara, Dhiren M.; Atatüre, Mete

    2014-01-01

    Nitrogen-vacancy (NV) centres in diamond are attractive for research straddling quantum information science, nanoscale magnetometry and thermometry. Whereas ultrapure bulk diamond NVs sustain the longest spin coherence times among optically accessible spins, nanodiamond NVs exhibit persistently poor spin coherence. Here we introduce high-purity nanodiamonds accommodating record-long NV coherence times, >60 μs, observed through universal dynamical decoupling. We show that the main contribution to decoherence comes from nearby nitrogen impurities rather than surface states. We protect the NV spin free precession, essential to d.c. magnetometry, by driving solely these impurities into the motional narrowing regime. This extends the NV free induction decay time from 440 ns, longer than that in type Ib bulk diamond, to 1.27 μs, which is comparable to that in type IIa (impurity-free) diamond. These properties allow the simultaneous exploitation of both high sensitivity and nanometre resolution in diamond-based emergent quantum technologies.

  4. Spin-current phenomena at high magnetic fields and high temperatures

    NASA Astrophysics Data System (ADS)

    Uchida, Ken-Ichi

    In the field of spintronics, many experimental and theoretical studies have been focused on spin-transport phenomena in paramagnet/ferromagnet junction systems, where a spin current plays a central role. After the first demonstration of spin transport in insulator-based systems, a Pt/YIG junction system becomes one of the prototype samples. In this system, itinerant spins in Pt and localized magnetic moments in YIG interact with each other via the interface s-d interaction, i.e., the spin-mixing conductance; this interaction is the basic mechanism underlying various spin-current-related phenomena, such as the spin pumping, the spin Seebeck effect, and the recently-discovered spin Hall magnetoresistance (SMR). In this talk, we report the observation of the longitudinal spin Seebeck effect (LSSE) and the SMR in Pt/YIG systems at high magnetic fields and high temperatures. The LSSE measurements in a high magnetic field range confirm that the observed voltage in the Pt/YIG systems is of magnon origin, providing a useful way to distinguish the LSSE from the anomalous Nernst effect induced by proximity ferromagnetism in Pt. The LSSE and SMR at high temperatures highlight the importance of the temperature dependence of the spin-mixing conductance at the Pt/YIG interface. These results will be helpful for obtaining full understanding of the mechanism of the LSSE and SMR. We thank E. Saitoh, S. Maekawa, G. E. W. Bauer, H. Adachi, Y. Ohnuma, T. Kikkawa, S. Daimon, Y. Shiomi, and J. Shiomi for their support and valuable discussions.

  5. Spin-on-carbon-hardmask with high wiggling resistance

    NASA Astrophysics Data System (ADS)

    Someya, Yasunobu; Shinjo, Tetsuya; Hashimoto, Keisuke; Nishimaki, Hirokazu; Karasawa, Ryo; Sakamoto, Rikimaru; Matsumoto, Takashi

    2012-03-01

    For the mass production of the advanced semiconductor device, the multi-layer process has been used for the essential technique {photoresist/ silicon contained hard mask (Si-HM)/ spin-on-carbon-hardmask (SOC)}. Spin -on-Carbon material plays a very important role during the etching process of substrates. The substrate etching process induces severe pattern deformations (called wiggling) especially with fine line/space patterns. Therefore, both the high etching resistances and the high wiggling resistance are demanded for SOC materials. In this study, we investigated the etching performances with several SOC materials. We found that the relationships between SOC properties and the resistance for wiggling generation. We will discuss the material design of novel SOC for high wiggling resistance.

  6. Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)].

    PubMed

    Scheurer, Andreas; Ako, Ayuk M; Saalfrank, Rolf W; Heinemann, Frank W; Hampel, Frank; Petukhov, Konstantin; Gieb, Klaus; Stocker, Michael; Müller, Paul

    2010-04-26

    Reaction of cobalt(II) chloride hexahydrate with N-substituted diethanolamines H(2)L(2-4) (3) in the presence of LiH in anhydrous THF leads under anaerobic conditions to the formation of three isostructural tetranuclear cobalt(II) complexes [Co(II) (4)(Cl)(4)(HL(2-4))(4)] (4) with a [Co(4)(mu(3)-O)(4)](4+) cubane core. According to X-ray structural analyses, the complexes 4 a,c crystallize in the tetragonal space group I4(1)/a, whereas for complex 4 b the tetragonal space group P$\\bar 4$ was found. In the solid state the orientation of the cubane cores and the formation of a 3D framework were controlled by the ligand substituents of the cobalt(II) cubanes 4. This also allowed detailed magnetic investigations on single crystals. The analysis of the SQUID magnetic susceptibility data for 4 a gave intramolecular ferromagnetic couplings of the cobalt(II) ions (J(1) approximately 20.4 K, J(2) approximately 7.6 K), resulting in an S=6 ground-state multiplet. The anisotropy was found to be of the easy-axis type (D=-1.55 K) with a resulting anisotropy barrier of Delta approximately 55.8 K. Two-dimensional electron-gas (2DEG) Hall magnetization measurements revealed that complex 4 a is a single-molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep-rate dependencies below a blocking temperature of about 4.4 K. The hysteresis loops collapse at zero field owing to fast quantum tunneling of the magnetization (QTM). The structural and electronic properties of cobalt(II) cubane 4 a, deposited on a highly oriented pyrolytic graphite (HOPG) surface, were investigated by means of STM and current imaging tunneling spectroscopy (CITS) at RT and standard atmospheric pressure. In CITS measurements the rather large contrast found at the expected locations of the metal centers of the molecules indicated the presence of a strongly localized LUMO.

  7. Properties of the low-spin high-spin interface during the relaxation of spin-crossover materials, investigated through an electro-elastic model

    SciTech Connect

    Slimani, A.; Boukheddaden, K. Varret, F.; Nishino, M.; Miyashita, S.

    2013-11-21

    The present work is devoted to the spatio-temporal investigations of spin-crossover lattices during their thermal relaxation from high- to low-spin state. The analysis is performed using Monte Carlo simulations on a distortable 2D lattice the sites of which are occupied by high-spin (HS) or low-spin (LS) atoms. The lattice is circular in shape and the HS to LS transformation results in single domain nucleation followed by growth and propagation processes. The evolution of the LS:HS interface is monitored during the relaxation process, through the mapping of spin states, displacement fields, local stresses, and elastic energy. The results show a curved interface, the curvature of which is reversed at the mid-transformation. The local stresses and elastic energy peak at the vicinity of the HS:LS interface, with sizeable dependence upon the position along the front line which evidences the edge effects.

  8. The spin bag mechanism of high temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Schrieffer, J. R.; Wen, X.-G.; Zhang, S.-C.

    1989-01-01

    In oxide superconductors the local suppression of antiferromagnetic correlations in the vicinity of a hole lowers the energy of the system. This quasi two-dimensional bag of weakened spin order follows the hole in its motion. In addition, holes prefer to share a bag, leading to a strong pairing attraction and a high Tc superconductivity. There are many experimental consequences of this mechanism for both the superconducting and normal phases.

  9. Lifetime measurement of high spin states in (75) Kr

    SciTech Connect

    Sheikh, Javid; Trivedi, T.; Maurya, K.; Mehrotra, I.; Palit, R.; Naik, Z.; Jain, H. C.; Negi, D.; Mahanto, G.; Kumar, R.; Singh, R.P.; Muralithar, S.; Pancholi, S.C.; Bhowmik, R.K.; Yang, Y-C; Sun, Y.; Dahl, A.; Raju, M.K.; Appannababu, S.; Kumar, S.; Choudhury, D.; Jain, A. K.

    2010-01-01

    The lifetimes of high spin states of {sup 75}Kr have been determined via {sup 50}Cr ({sup 28}Si, 2pn) {sup 75}Kr reaction in positive parity band using the Doppler-shift attenuation method. The transition quadrupole moments Q deduced from lifetime measurements have been compared with {sup 75}Br. Experimental results obtained from lifetime measurement are interpreted in the framework of projected shell model.

  10. High-mobility ultrathin semiconducting films prepared by spin coating

    NASA Astrophysics Data System (ADS)

    Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

    2004-03-01

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  11. High-spin structure of {sup 102}Ru

    SciTech Connect

    Sohler, D.; Timar, J.; Molnar, J.; Dombradi, Zs.; Krasznahorkay, A.; Zolnai, L.; Rainovski, G.; Joshi, P.; Wadsworth, R.; Jenkins, D.G.; Raddon, P.M.; Simons, A.J.; Wilkinson, A.R.; Starosta, K.; Fossan, D.B.; Koike, T.; Vaman, C.; Algora, A.; Bednarczyk, P.; Curien, D.

    2005-06-01

    High-spin states in the nucleus {sup 102}Ru have been investigated via the {sup 96}Zr({sup 13}C,{alpha}3n) reaction at beam energies of 51 and 58 MeV, using the euroball IV {gamma}-ray spectrometer and the diamant charged particle array. Several new high-spin bands have been established. The ground-state band has been extended up to E{sub x}{approx}12 MeV with I{sup {pi}}=(26{sup +}); the previously published negative-parity bands have been extended up to E{sub x}{approx}11 and {approx} 9 MeV with I{sup {pi}}=(23{sup -}) and (20{sup -}), respectively. The deduced high-spin structure has been compared with Woods-Saxon total Routhian surface calculations and, on the basis of the measured Routhians, aligned angular momenta, and B(M1)/B(E2) ratios, {nu}h{sub 11/2}(g{sub 7/2},d{sub 5/2}) configurations are suggested for the negative-parity structures.

  12. High-mobility ultrathin semiconducting films prepared by spin coating.

    PubMed

    Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

    2004-03-18

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  13. Cobalt(II) sheet-like systems based on diacetic ligands: from subtle structural variances to different magnetic behaviors.

    PubMed

    Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Delgado, Fernando S; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2009-07-06

    The preparation, X-ray crystallography, and magnetic investigation of the compounds [Co(H(2)O)(2)(phda)](n) (1), [Co(phda)](n) (2), and [Co(chda)](n) (3) [H(2)phda = 1,4-phenylenediacetic acid and H(2)chda = 1,1-cyclohexanediacetic acid] are described herein. The cobalt atoms in this series are six- (1) and four-coordinated (2 and 3) in distorted octahedral (CoO(6)) and tetrahedral (CoO(4)) environments. The structures of 1-3 consists of rectangular-grids which are built up by sheets of cobalt atoms linked through anti-syn carboxylate bridges, giving rise to either a three-dimensional structure across the phenyl ring (1 and 2) or to regularly stacked layers with the cyclohexyl groups acting as organic separators (3). The magnetic properties of 1-3 were investigated as a function of the temperature and the magnetic field. Ferromagnetic coupling between the six-coordinate cobalt(II) ions across the anti-syn carboxylate bridge occurs in 1 (J = +1.2 cm(-1)) whereas antiferromagnetic coupling among the tetrahedral cobalt(II) centers within the sheets is observed in 2 and 3 [J = -1.63 (2) and -1.70 cm(-1) (3)] together with a spin-canted structure in 3 giving rise a long-range magnetic ordering (T(c) = 7.5 K).

  14. [Study on the thermodynamical molar absorptivity of the interaction of cobalt(II) and the histidine].

    PubMed

    Chen, L; Zhang, D; Yang, D; He, Z; Wang, Y

    1999-02-01

    In this paper UV-Vis absorption spectrum of Cobalt(II) with the histidine and the thermodynamical molar absorptivity of the complex reaction were determined and the complexes of Cobalt(II) with the histidine were compared in terms of stability.

  15. Recent advances in the study of hyperdeformation at high spin

    NASA Astrophysics Data System (ADS)

    Abusara, Hazem; Afanasjev, A. V.

    2008-10-01

    The systematic investigation of hyperdeforation (HD) at high spin in the Z=40-58 part of nuclear chart has been performed in the framework of the cranked relativistic mean field theory. The properties of the HD bands such as quadrupole transition moments Qt, dynamic J^(2) and kinematic J^(1) moments of inertia have been studied. These observables are affected by centrifugal stretching. Our self-consistent calculations suggest that necking degree of freedom should play an important role in some nuclei at hyperdeformation. It is especially pronounced in the proton density distribution due to the repulsive Coulomb force. The density of the HD bands is high in the spin range where they are yrast or close to yrast in the majority of cases. In these cases the observation of discrete HD bands will most likely be impossible because the feeding intensity will be redistributed among many bands, thus, dropping below the observational limit of the experimental facilities. The calculations indicate Cd isotopes as the best candidates for a search of discrete HD bands. The HD configurations become yrast at lower spins in neutron-deficient nuclei than in the ones of the valley of β-stability. [1] W.Koepf and P.Ring, Nucl. Phys. A511, 279(1990), [2] A.V.Afanasjev and H.Abusara (submitted to Physical Review C)

  16. Collectivity of high spin states in {sup 84}Zr

    SciTech Connect

    Lister, C.J.; Blumenthal, D.; Crowell, B.

    1995-08-01

    {sup 84}Zr is one of the most extensively studied of the A {approximately} 80 rotors, both from theoretical and experimental approaches. It was predicted to be a good candidate to support superdeformation, and to show interesting spectroscopic properties including saturation of its shell-model space at lower spin. We performed an experiment using Gammasphere in its early implementation phase. The reaction of {sup 29}Si on {sup 58}Ni was used to strongly populate {sup 84}Zr at high spin. Thin and thick targets were used to allow the extraction of transitional matrix elements at very high spin, and to allow a sensitive search for superdeformed states. Data analysis is in progress. The large data set allowed us to extend the previously known bands considerably. Candidates for a staggered M1-band, found previously {sup 86}Zr, were located. To date, no evidence for superdeformed bands was found. Analysis was slowed by the relocation of all the participants in this experiment, but we hope to complete the lifetime analysis this year. This analysis has become especially topical, due to reported measurements of superdeformation in this region.

  17. High Frequency QPOs due to Black Hole Spin

    NASA Technical Reports Server (NTRS)

    Kazanas, Demos; Fukumura, K.

    2009-01-01

    We present detailed computations of photon orbits emitted by flares at the innermost stable circular orbit (ISCO) of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. a > 0.94 M, flare a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of T approximates 14 M. This constant time delay, then, leads to a power spectrum with a QPO at a frequency nu approximates 1/14M, even for a totally random ensemble of such flares. Observation of such a QPO will provide incontrovertible evidence for the high spin of the black hole and a very accurate, independent, measurement of its mass.

  18. Deformed band structures at high spin in 200Tl

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Soumik; Bhattacharyya, S.; Das Gupta, S.; Pai, H.; Mukherjee, G.; Palit, R.; Xu, F. R.; Wu, Q.; Shrivastava, A.; Asgar, Md. A.; Banik, R.; Bhattacharjee, T.; Chanda, S.; Chatterjee, A.; Goswami, A.; Nanal, V.; Pandit, S. K.; Saha, S.; Sethi, J.; Roy, T.; Thakur, S.

    2017-01-01

    High-spin band structures of 200Tl have been studied by γ -ray spectroscopic methods using the 198Pt(7Li,5 n )200Tl reaction at 45 MeV of beam energy. The level scheme of 200Tl has been extended significantly and several new band structures have been established with the observation of 60 new transitions. The π h9 /2⊗ν i13 /2 oblate band has been extended beyond the particle alignment frequencies. The band structures and the other excited states have been compared with the neighboring odd-odd Tl isotopes. Total Routhian surface calculations have been performed to study the deformation and shape changes as a function of spin in this nucleus. These calculations could reproduce the particle alignment frequency and suggest that the neutron pair alignment in ν i13 /2 orbital induces γ softness in 200Tl.

  19. High spin spectroscopy and shears mechanism in {sup 107}In

    SciTech Connect

    Negi, D.; Mohanto, G.; Kumar, R.; Singh, R. P.; Muralithar, S.; Bhowmik, R. K.; Trivedi, T.; Dhal, A.; Kumar, S.; Kumar, V.; Roy, S.; Raju, M. K.; Appannababu, S.; Kaur, J.; Bhati, A. K.; Sinha, R. K.; Pancholi, S. C.

    2010-05-15

    High spin states of {sup 107}In have been investigated using the reaction {sup 94}Mo({sup 16}O,p2n){sup 107}In at a beam energy of 70 MeV. A total of 62 new gamma transitions have been placed in the level scheme and several DELTAI=1 sequences and one DELTAI=2 sequence have been found. Lifetime measurements using the Doppler-shift attenuation method (DSAM) have been carried out for band states of DELTAI=1 and DELTAI=2. A decreasing trend of B(M1) strengths with increasing spin deduced for the DELTAI=1 band indicates the presence of a shears mechanism. The experimental data for this band are compared with the tilted axis cranking (TAC) calculations. The DELTAI=2 band has been found to be a deformed band with beta{sub 2}approx0.2.

  20. High-spin level scheme of {sup 194}Pb

    SciTech Connect

    Kutsarova, T.; Stefanova, E. A.; Minkova, A.; Lalkovski, S.; Korichi, A.; Lopez-Martens, A.; Hannachi, F.; Huebel, H.; Goergen, A.; Jansen, A.; Schoenwasser, G.; Khoo, T. L.; Herskind, B.; Bergstroem, M.; Bazzacco, D.; Podolyak, Z.

    2009-01-15

    High-spin states in {sup 194}Pb have been populated in the {sup 168}Er({sup 30}Si,4n) reaction at 142 MeV. The emitted {gamma} rays were detected by the EUROBALL III multidetector array. The level scheme was considerably extended and many previously observed {gamma}-ray transitions were reordered. Four new magnetic rotational bands were observed. The energies and spins of the bandheads of all previously observed magnetic rotational bands were corrected based on the observation of new transitions. From nine observed bands, only one could not be connected to the lower lying states. Based on comparison systematics with neighboring Pb isotopes and tilted-axis cranking model calculations previously reported, configuration assignments to the observed bands have been made.

  1. Summary of the 9th international symposium on high energy spin-physics

    SciTech Connect

    Prescott, C.Y.

    1990-11-01

    Summarizing an international conference in high energy spin physics is never an easy task, because of the wide-ranging subjects in physics and technology that are involved. I have chosen to organize the topics of this conference into three broad categories relating to spin; intrinsic spin; composite spin; and spin, the experimental tool. In the first category, I will briefly revisit some historical and recent developments to set a background. In the second category, composite spin, I will discuss the status and developments in several areas, including magnetic moments of baryons, hyperon polarization in high energy high p {perpendicular} production, transverse polarization and asymmetries from transversely polarized targets in high p {perpendicular} scattering, spin structure of the proton, and the Bjorken sum rule. In the third category, I will discuss the steady, and at times rapid, progress in spin technology. In this part I include recent progress in high energy facilities, and comment on the highlights of the Workshops.

  2. Structure of odd-odd 136La at high spin

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Tumpa; Chanda, Somen; Bhattacharyya, Sarmishtha; Basu, Swapan Kumar; Bhowmik, R. K.; Muralithar, S.; Singh, R. P.; Pattabiraman, N. S.; Ghugre, S. S.; Datta Pramanik, U.; Bhattacharya, S.

    2005-04-01

    The high spin states in the N=79 odd-odd 136La nucleus have been investigated by in-beam γ-spectroscopic techniques following the 130Te( 11B, 5 n) 136La reaction at E=52 MeV using an array, consisting of eight Compton-suppressed clover germanium detectors. Thirty nine new γ rays have been assigned to 136La on the basis of γ ray singles and γγ-coincidence data. The level scheme of 136La has been extended above the known 115 ms isomer upto an excitation energy of 4.6 MeV and spin 18 ℏ. Thirty one new levels have been proposed and spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced asymmetry ratios and polarisation information for the de-exciting transitions. The observed positive parity yrast band has been compared with the theoretical calculation, done within the framework of particle rotor coupling model (PRM) where the two odd quasi-particles are coupled to an axially symmetric core. The level structure has been discussed in the light of the known systematics of the neighbouring N=79 isotonic nuclei.

  3. Excitations for lattice ferromagnetic classical spin systems at high temperature: noneven single-spin distributions

    PubMed

    Schor; O'Carroll

    2000-06-01

    We consider general d-dimensional lattice ferromagnetic spin systems with nearest neighbor interactions in the high temperature region (beta<1). Each model is characterized by a single-site a priori spin probability distribution taken to be noneven. We state our results in terms of the parameter alpha=(<&smacr; (4)>-3<&smacr; (2)>(2)-<&smacr; (3)>(2)<&smacr; (2)>(-1))/(<&smacr; (4)>-<&smacr; (2)>(2)-<&smacr; (3)>(2)<&smacr; (2)>(-1)), where &smacr;=s-, and denotes the kth moment of the single-site distribution. Associated with the model is a lattice quantum field theory which is known to contain a particle of mass m approximately ln beta. Assuming <&smacr;(3)> not equal0 we show that for alpha>0, beta small, there exists a bound state with mass below the two-particle threshold 2m. For alpha<0 bound states do not exist. These results are obtained using a Bethe-Salpeter (BS) equation in the ladder approximation in conjunction with a representation for the inverse of the two-point function designed to analyze the spectrum below but close to 2m.

  4. A 3D-printed high power nuclear spin polarizer.

    PubMed

    Nikolaou, Panayiotis; Coffey, Aaron M; Walkup, Laura L; Gust, Brogan M; LaPierre, Cristen D; Koehnemann, Edward; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-01-29

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of (129)Xe and (1)H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of "off-the-shelf" components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity (129)Xe polarization values in a 0.5 L optical pumping cell, including ∼74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the (129)Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10(-2) min(-1)] and in-cell (129)Xe spin-lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for (129)Xe and Rb (PRb ∼ 96%). Hyperpolarization-enhanced (129)Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications.

  5. Microcoil high-resolution magic angle spinning NMR spectroscopy.

    PubMed

    Janssen, Hans; Brinkmann, Andreas; van Eck, Ernst R H; van Bentum, P Jan M; Kentgens, Arno P M

    2006-07-12

    We report the construction of a dual-channel microcoil nuclear magnetic resonance probehead allowing magic-angle spinning for mass-limited samples. With coils down to 235 mum inner diameter, this allows high-resolution solid-state NMR spectra to be obtained for amounts of materials of a few nanoliters. This is demonstrated by the carbon-13 spectrum of a tripeptide and a single silk rod, prepared from the silk gland of the Bombyx mori silkworm. Furthermore, the microcoil allows for radio frequency field strengths well beyond current probe technology, aiding in getting the highest possible resolution by efficiently decoupling the observed nuclei from the abundantly present proton nuclei.

  6. Observation of a single spin by transferring its coherence to a high level macroscopic pure state

    SciTech Connect

    Kawamura, Minaru

    2014-12-04

    We discuss about quantum measurement of a single spin in a superconducting RF resonator, where amplification of coherence of the spin is enabled by transferring its coherence to the harmonic oscillator in an non-coherent state with high energy level. This quantum amplification allows that a single spin can induce macroscopic current to permits observation of a single spin state in the number and phase uncertainty relation.

  7. High-spin nuclear structure studies with radioactive ion beams

    SciTech Connect

    Baktash, C.

    1992-12-31

    Two important developments in the sixties, namely the advent of heavy-ion accelerators and fabrication of Ge detectors, opened the way for the experimental studies of nuclear properties at high angular momentum. Addition of a new degree of freedom, namely spin, made it possible to observe such fascinating phenomena as occurrences and coexistence of a variety of novel shapes, rise, fall and occasionally rebirth of nuclear collectivity, and disappearance of pairing correlations. Today, with the promise of development of radioactive ion beams (RIB) and construction of the third-generation Ge-detection systems (GAMMASPHERE and EUROBALL), the authors are poised to explore new and equally fascinating phenomena that have been hitherto inaccessible. With the addition of yet another dimension, namely the isospin, they will be able to observe and verify predictions for exotic shapes as varied as rigid triaxiality, hyperdeformation and triaxial octupole shapes, or to investigate the T = 0 pairing correlations. In this paper, they shall review, separately for neutron-deficient and neutron-rich nuclei, these and a few other new high-spin physics opportunities that may be realized with RIB. Following this discussion, they shall present a list of the beam species, intensities and energies that are needed to fulfill these goals. The paper will conclude with a description of the experimental techniques and instrumentations that are required for these studies.

  8. Superdeformed band at very high spin in {sup 140}Nd

    SciTech Connect

    Neusser, A.; Huebel, H.; Al-Khatib, A.; Bringel, P.; Buerger, A.; Nenoff, N.; Schoenwasser, G.; Singh, A.K.; Petrache, C.M.; Lo Bianco, G.; Ragnarsson, I.; Hagemann, G.B.; Herskind, B.; Jensen, D.R.; Sletten, G.; Fallon, P.; Goergen, A.; Bednarczyk, P.; Curien, D.; Gangopadhyay, G.

    2004-12-01

    A new high-spin superdeformed band has been discovered in {sub 60}{sup 140}Nd{sub 80}. It was populated in the {sup 96}Zr({sup 48}Ca,4n) reaction and investigated using the EUROBALL {gamma}-ray spectrometer array. The band is observed in the approximate spin range of I=36 to 66. It is associated with shell gaps around Z=60 and at N=80 at large deformation. These gaps produce a pronounced minimum in the calculated total Routhian surfaces at a quadrupole deformation of {epsilon}{sub 2}=0.45. The new band which lies between the high-deformation bands in the A{approx_equal}130 region and the superdeformed bands in A{approx_equal}150 nuclei provides insight into the development of the deformation between these two regions. Two possible configurations are suggested involving four neutrons of i{sub 13/2} origin ({nu}6{sup 4}) and either six protons of h{sub 11/2}/h{sub 9/2} origin ({pi}5{sup 6}) or five protons of h{sub 11/2}/h{sub 9/2} and one of i{sub 13/2} origin ({pi}5{sup 5}6{sup 1})

  9. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    DOE PAGES

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-10-26

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonancemore » can be significantly narrowed, by a factor of 10–100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. As a result, the method can be applied to a wide range of solid-state systems.« less

  10. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    SciTech Connect

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-10-26

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonance can be significantly narrowed, by a factor of 10–100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. As a result, the method can be applied to a wide range of solid-state systems.

  11. Triaxial superdeformed and normal-deformed high-spin band structures in {sup 170}Hf

    SciTech Connect

    Neusser-Neffgen, A.; Huebel, H.; Bringel, P.; Domscheit, J.; Mergel, E.; Nenoff, N.; Singh, A.K.; Hagemann, G.B.; Jensen, D.R.; Bhattacharya, S.; Curien, D.; Dorvaux, O.; Hannachi, F.; Lopez-Martens, A.

    2006-03-15

    The high-spin structure of {sup 170}Hf was investigated using the EUROBALL spectrometer. The previously known level scheme was extended in the low-spin region as well as to higher spins, and several new bands were discovered. In particular, two bands were identified which show the characteristics of triaxial superdeformation. One of these bands is strongly populated, and its excitation energy and spins are established. Configuration assignments are made to the normal-deformed bands based on comparisons of their properties with cranked shell model calculations. The results for the very high spin states provide important input for such calculations.

  12. High-spin research with HERA (High Energy-Resolution Array)

    SciTech Connect

    Diamond, R.M.

    1987-06-01

    The topic of this report is high spin research with the High Energy Resolution Array (HERA) at Lawrence Berkeley Laboratory. This is a 21 Ge detector system, the first with bismuth germanate (BGO) Compton suppression. The array is described briefly and some of the results obtained during the past year using this detector facility are discussed. Two types of studies are described: observation of superdeformation in the light Nd isotopes, and rotational damping at high spin and excitation energy in the continuum gamma ray spectrum.

  13. High spin γ -ray spectroscopy in 41Ca

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, R.; Samanta, S.; Das, S.; Bhattacharjee, S. S.; Raut, R.; Ghugre, S. S.; Sinha, A. K.; Garg, U.; Chakrabarti, R.; Mukhopadhyay, S.; Dhal, A.; Singh, R. P.; Madhavan, N.; Muralithar, S.

    2016-11-01

    High spin states in 41Ca have been investigated by using γ -ray spectroscopic techniques following the 27Al(16O,p n )41Ca fusion-evaporation reaction. Around twelve new transitions belonging to 41Ca have been observed and placed in the level scheme, which now has been extended up to Ex˜9 MeV. The spin-parity assignments for the observed levels were arrived at following the analysis of both the coincidence intensity anisotropies and linear polarization measurements. The established 5p-4h band was extended up to Jπ=19 /2- . The observations of Doppler shape and shifts facilitated the estimation of the level lifetimes by using the Doppler shift attenuation method. The lifetimes were validated with respect to previous measurements and lifetime of a few levels has been arrived at for the first time. Shell-model calculations were carried out to explain the observed level structure of the nucleus and are indicative of both single-particle and collective degrees of freedom in this N ˜Z ˜20 nucleus.

  14. High-pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg 2SiO 4) reacted with supercritical CO 2 and H 2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  15. High-pressure magic angle spinning nuclear magnetic resonance.

    PubMed

    Hoyt, David W; Turcu, Romulus V F; Sears, Jesse A; Rosso, Kevin M; Burton, Sarah D; Felmy, Andrew R; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ(13)C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg(2)SiO(4)) reacted with supercritical CO(2) and H(2)O at 150 bar and 50°C are reported, with relevance to geological sequestration of carbon dioxide.

  16. High-pressure magic angle spinning nuclear magnetic resonance

    SciTech Connect

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. Finally, as an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg2SiO4) reacted with supercritical CO2 and H2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  17. A 3D-Printed High Power Nuclear Spin Polarizer

    PubMed Central

    Nikolaou, Panayiotis; Coffey, Aaron M.; Walkup, Laura L.; Gust, Brogan M.; LaPierre, Cristen D.; Koehnemann, Edward; Barlow, Michael J.; Rosen, Matthew S.; Goodson, Boyd M.; Chekmenev, Eduard Y.

    2015-01-01

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of 129Xe and 1H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of “off-the-shelf” components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity 129Xe polarization values in a 0.5 L optical pumping cell, including ~74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the 129Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10−2 min−1] and in-cell 129Xe spin−lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for 129Xe and Rb (PRb ~ 96%). Hyperpolarization-enhanced 129Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications. PMID:24400919

  18. New type of single chain magnet: pseudo-one-dimensional chain of high-spin Co(II) exhibiting ferromagnetic intrachain interactions.

    PubMed

    Tangoulis, V; Lalia-Kantouri, M; Gdaniec, M; Papadopoulos, Ch; Miletic, V; Czapik, A

    2013-06-03

    Two new six-coordinated high-spin Co(II) complexes have been synthesized through the reactions of Co(II) salts with dipyridylamine (dpamH) and 5-nitro-salicylaldehyde (5-NO2-saloH) or 3-methoxy-salicylaldehyde (3-OCH3-saloH) under argon atmosphere: [Co(dpamH)2(5-NO2-salo)]NO3 (1) and [Co(dpamH)2(3-OCH3-salo)]NO3·1.3 EtOH·0.4H2O (2). According to the crystal packing of compound 1, two coordination cations are linked with two nitrate anions into a cyclic dimeric arrangement via N-H···O and C-H···O hydrogen bonds. In turn, these dimers are assembled into (100) layers through π-π stacking interactions between inversion-center related pyridine rings of the dpamH ligands. The crystal packing of compound 2 reveals a 1D assembly consisting solely from the coordination cations, which is formed by π-π stacking interactions between pyridine rings of one of the dpamH along the [010] and another 1D assembly of the coordination cations and nitrate anions through the N-H···O hydrogen-bonding interactions along the [001] direction. All complexes were magnetically characterized, and a new approximation method was used to fit the magnetic susceptibility data in the whole temperature range 2-300 K on the basis of an empirical expression which allows the treatment of each cobalt(II) ion in axial symmetry as an effective spin S(eff) = 1/2. In zero-field, dynamic magnetic susceptibility measurements show slow magnetic relaxation below 5.5 K for compound 2. The slow dynamics may originate from the motion of broad domain walls and is characterized by an Arrhenius law with a single energy barrier Δr/k(B) = 55(1) K for the [10-1488 Hz] frequency range. In order to reveal the importance of the crystal packing in the SCM behavior, a gentle heating process to 180 °C was carried out to remove the solvent molecules. The system, after heating, undergoes a major but not complete collapse of the network retaining to a small percentage its SCM character.

  19. High-spin yrast structure of {sup 159}Ho

    SciTech Connect

    Ollier, J.; Simpson, J.; Riley, M. A.; Wang, X.; Aguilar, A.; Teal, C.; Paul, E. S.; Nolan, P. J.; Petri, M.; Rigby, S. V.; Thomson, J.; Unsworth, C.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Zhu, S.; Darby, I. G.; Hartley, D. J.; Kondev, F. G.

    2011-08-15

    An investigation of the yrast structure of the odd-Z {sup 159}Ho nucleus to high spin has been performed. The {sup 159}Ho nucleus was populated by the reaction {sup 116}Cd({sup 48}Ca,p4n{gamma}) at a beam energy of 215 MeV, and resulting {gamma} decays were detected by the Gammasphere spectrometer. The h{sub 11/2} yrast band has been significantly extended up to I{sup {pi}=}75/2{sup -} (tentatively 79/2{sup -}). A lower frequency limit for the second (h{sub 11/2}){sup 2} proton alignment was extracted consistent with the systematics of this alignment frequency, indicating an increased deformation with neutron number in the Ho isotopes. The energy-level splitting between the signature partners in the h{sub 11/2} structures of the Ho isotopes and the neighboring N=92 isotones is discussed.

  20. Cobalt(II) complexes with hydroxypyridines and halogenides

    NASA Astrophysics Data System (ADS)

    Dojer, Brina; Pevec, Andrej; Jagličić, Zvonko; Kristl, Matjaž

    2017-01-01

    We have synthesized and characterized two new cobalt(II) complexes: difluoridotetrakis(3-hydroxypyridine-κN)cobalt(II), [CoF2(C5H5NO)4] (1) and hexa(2-pyridone-κO)cobalt(II) tetrachloridocobaltate(II), [Co(C5H5NO)6][CoCl4] (2). The complexes were prepared by solvothermal synthesis. A methanol solution of hydroxypyridine was added to water solution of cobalt(II) acetate dihydrate followed by a few drops of concentrated hydrofluoric or hydrochloric acid into the mixture. The crystals of the compounds 1 and 2 are stable on air. The compounds were characterized structurally by single-crystal X-ray diffraction analysis, spectrally by FT-IR spectroscopy and thermally. Thermal analysis showed that the final product of both complexes after heating to 900 °C is elemental cobalt. The interactions between building units in the crystal structures include intra- and intermolecular hydrogen bonds in both compounds and π-π interactions in compound 2.

  1. Synthesis, Characterization, and Use of a Cobalt(II) Complex as an NMR Shift Reagent.

    ERIC Educational Resources Information Center

    Goff, Harold M.; And Others

    1982-01-01

    Describes procedures for preparing acetylacetonate complex of cobalt(II), followed by spectrophotometric analysis to characterize the material, with additional characterization methods supplied by students to provide open-ended dimension for the experiment. (SK)

  2. Spin-spin relaxation of protons in ferrofluids characterized with a high-Tc superconducting quantum interference device-detected magnetometer in microtesla fields

    NASA Astrophysics Data System (ADS)

    Liao, Shu-Hsien; Liu, Chieh-Wen; Yang, Hong-Chang; Chen, Hsin-Hsien; Chen, Ming-Jye; Chen, Kuen-Lin; Horng, Herng-Er; Wang, Li-Min; Yang, Shieh-Yueh

    2012-06-01

    In this work, the spin-spin relaxation of protons in ferrofluids is characterized using a high-Tc SQUID-based detector in microtesla fields. We found that spin-spin relaxation rate is enhanced in the presence of superparamagnetic nanoparticles. The enhanced relaxation rates are attributed to the microscopic field gradients from magnetic nanoparticles that dephase protons' spins nearby. The relaxation rates decrease when temperatures increase. Additionally, the alternating current magnetic susceptibility was inversely proportional to temperature. Those characteristics explained the enhanced Brownian motion of nanoparticles at high temperatures. Characterizing the relaxation will be helpful for assaying bio-molecules and magnetic resonance imaging in microtesla fields.

  3. Electrically detected electron spin resonance in a high-mobility silicon quantum well.

    PubMed

    Matsunami, Junya; Ooya, Mitsuaki; Okamoto, Tohru

    2006-08-11

    The resistivity change due to electron spin resonance (ESR) absorption is investigated in a high-mobility two-dimensional electron system formed in a Si/SiGe heterostructure. Results for a specific Landau level configuration demonstrate that the primary cause of the ESR signal is a reduction of the spin polarization, not the effect of electron heating. The longitudinal spin relaxation time T1 is obtained to be of the order of 1 ms in an in-plane magnetic field of 3.55 T. The suppression of the effect of the Rashba fields due to high-frequency spin precession explains the very long T1.

  4. Dinuclear cobalt(II) and copper(II) complexes with a Py2N4S2 macrocyclic ligand.

    PubMed

    Núñez, Cristina; Bastida, Rufina; Lezama, Luis; Macías, Alejandro; Pérez-Lourido, Paulo; Valencia, Laura

    2011-06-20

    The interaction between Co(II) and Cu(II) ions with a Py(2)N(4)S(2)-coordinating octadentate macrocyclic ligand (L) to afford dinuclear compounds has been investigated. The complexes were characterized by microanalysis, conductivity measurements, IR spectroscopy and liquid secondary ion mass spectrometry. The crystal structure of the compounds [H(4)L](NO(3))(4), [Cu(2)LCl(2)](NO(3))(2) (5), [Cu(2)L(NO(3))(2)](NO(3))(2) (6), and [Cu(2)L(μ-OH)](ClO(4))(3)·H(2)O (7) was also determined by single-crystal X-ray diffraction. The [H(4)L](4+) cation crystal structure presents two different conformations, planar and step, with intermolecular face-to-face π,π-stacking interactions between the pyridinic rings. Complexes 5 and 6 show the metal ions in a slightly distorted square-pyramidal coordination geometry. In the case of complex 7, the crystal structure presents the two metal ions joined by a μ-hydroxo bridge and the Cu(II) centers in a slightly distorted square plane or a tetragonally distorted octahedral geometry, taking into account weak interactions in axial positions. Electron paramagnetic resonance spectroscopy is in accordance with the dinuclear nature of the complexes, with an octahedral environment for the cobalt(II) compounds and square-pyramidal or tetragonally elongated octahedral geometries for the copper(II) compounds. The magnetic behavior is consistent with the existence of antiferromagnetic interactions between the ions for cobalt(II) and copper(II) complexes, while for the Co(II) ones, this behavior could also be explained by spin-orbit coupling.

  5. Low-power decoupling at high spinning frequencies in high static fields.

    PubMed

    Weingarth, Markus; Bodenhausen, Geoffrey; Tekely, Piotr

    2009-08-01

    We demonstrate that heteronuclear decoupling using a Phase-Inverted Supercycled Sequence for Attenuation of Rotary ResOnance (PISSARRO) is very efficient at high spinning frequencies (nu(rot)=60kHz) and high magnetic fields (900MHz for protons at 21T) even with moderate radio-frequency decoupling amplitudes (nu(1)(I)=15kHz), despite the wide range of isotropic chemical shifts of the protons and the increased effect of their chemical shift anisotropy.

  6. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    SciTech Connect

    Adelnia, Fatemeh; Lascialfari, Alessandro; Mariani, Manuel; Ammannato, Luca; Caneschi, Andrea; Rovai, Donella; Winpenny, Richard; Timco, Grigore; Corti, Maurizio Borsa, Ferdinando

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  7. Synthesis, structure, properties and immobilization on a gold surface of the monoribbed-functionalized tris-dioximate cobalt(II) clathrochelates and an electrocatalytic hydrogen production from H+ ions.

    PubMed

    Voloshin, Y Z; Belov, A S; Vologzhanina, A V; Aleksandrov, G G; Dolganov, A V; Novikov, V V; Varzatskii, O A; Bubnov, Y N

    2012-05-28

    The cycloaddition of the mono- and dichloroglyoximes to the cobalt(II) bis-α-benzyldioximate afforded the cobalt(II) mono- and dichloroclathrochelates in moderate yields (40-60%). These complexes undergo nucleophilic substitution of their reactive chlorine atoms with aliphatic amines, alcohols and thiolate anions. In the case of ethylenediamine and 1,2-ethanedithiol, only the macrobicyclic products with α,α'-N(2)- and α,α'-S(2)-alicyclic six-numbered ribbed fragments were obtained. The cobalt(II) cage complexes with terminal mercapto groups were synthesized using aliphatic dithiols. The crystal and molecular structures of the six cobalt(II) clathrochelates were obtained by X-ray diffraction. Their CoN(6)-coordination polyhedra possess a geometry intermediate between a trigonal prism and a trigonal antiprism, and the encapsulated cobalt(II) ions are shifted from their centres due to the structural Jahn-Teller effect with the Co-N distances varying significantly (by 0.10-0.26 Å). The electrochemistry of the complexes obtained was studied by cyclic voltammetry (CV). The anodic waves correspond to the quasi-reversible Co(2+/3+) oxidations, whereas the cathodic ranges contain the quasi-reversibile waves assigned to the Co(2+/+) reductions; all the cobalt(i)-containing clathrochelate anions formed are stable in the CV time scale. The electrocatalytic properties of the cobalt complexes obtained were studied in the production of hydrogen from H(+) ions: the addition of HClO(4) resulted in the formation of the same catalytic cathodic reduction Co(2+/+) waves. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H(2) in high Faraday yields. The efficiency of this electrocatalytic process was enhanced by an immobilization of the complexes with terminal mercapto groups on a surface of the working gold electrode.

  8. Direct observation of a highly spin-polarized organic spinterface at room temperature

    PubMed Central

    Djeghloul, F.; Ibrahim, F.; Cantoni, M.; Bowen, M.; Joly, L.; Boukari, S.; Ohresser, P.; Bertran, F.; Le Fèvre, P.; Thakur, P.; Scheurer, F.; Miyamachi, T.; Mattana, R.; Seneor, P.; Jaafar, A.; Rinaldi, C.; Javaid, S.; Arabski, J.; Kappler, J. -P; Wulfhekel, W.; Brookes, N. B.; Bertacco, R.; Taleb-Ibrahimi, A.; Alouani, M.; Beaurepaire, E.; Weber, W.

    2013-01-01

    Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen π orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature. PMID:23412079

  9. (Evolution of nuclear collectivity at high spins and temperatures)

    SciTech Connect

    Baktash, C.

    1989-09-28

    The traveler attended and presented an invited talk entitled Evolution of nuclear collectivity at high spins and temperatures'' at the XII Workshop on Nuclear Physics at Iguazu Falls, Argentina. Following the conference, the traveler visited the TANDAR Laboratory in Buenos Aires, Argentina, for two weeks. This trip was the first by one of the principal investigators of an ORNL-TANDAR exchange program that was recently approved and funded by the NSF. The results of the extensive consultations that the traveler had with his Argentine collaborators, A. J. Kreiner and G. Garcia-Bermudez, can be summarized as follows: (1) discussed the spectroscopy work on several nuclei of common interest that are being studied at the two laboratories, (2) agreed on the first joint experiments to be performed at the Holifield and TANDAR facilities, (3) developed a tentative timetable for the future visits by both groups, and (4) continued with the analysis of data on {sup 82}Sr taken earlier at ORNL in collaboration with Dr. Garcia-Bermudez.

  10. Study of High Spin States in ^192Au

    NASA Astrophysics Data System (ADS)

    Gurdal, G.; Beausang, C. W.; Balabanski, D.; Novak, J. R.; Hecht, A. A.; Caprio, M.; Cooper, J. R.; Krücken, R.; Casten, R. F.; Zamfir, N. V.; Berant, Z.; Barton, C. J.; Pietralla, N.; Erduran, M. N.; Akkus, B.; Erturk, S.; Yigitoglu, I.; Oktem, Y.; Hartley, D. J.; Gjongolov, M.; Goon, J.

    2001-10-01

    Doubly odd nuclei in the A ~190 mass region are predicted to be good candidates to search for evidence of chiral symmetry breaking. Indeed evidence for a pair of chiral twin bands has recently been reported in ^188Ir [1]. To search for additional examples of this phenomenon we studied the high spin structures in the neighboring nuclei. ^192Au and ^190Ir were populated using the ^186W(^11B,5n) and ^186W(^11B,α3n) reactions at a beam energy of 68 MeV. Gamma-ray coincidence measurements were performed using the YRAST Ball at WNSL, Yale University. Analysis is in progress and preliminary results will be presented. This work is supported by the U.S. D.O.E under Grant Numbers DE-FG02-91ER-40609, DE-FG02-88ER-40417, DE-FG02-96ER-40983 and by the DFG under Grant Number Pi 393/1-1 and by the Research Fund of The University of Istanbul under Grant Number 1582/19032001 . [1] D. Balabanski et al, to be published.

  11. High-spin band structure of 192Tl

    NASA Astrophysics Data System (ADS)

    Kreiner, A. J.; Filevich, A.; García Bermúdez, G.; Mariscotti, M. A. J.; Baktash, C.; der Mateosian, E.; Thieberger, P.

    1980-03-01

    High-spin states in 192Tl, excited through the 181Ta(18O,7n) and 181Ta(16O,5n) reactions, were studied using in-beam γ-ray spectroscopic techniques. Excitation functions, activity spectra, γ-ray angular distributions, and multidimensional coincidences were measured. The strongly Coríolis-distorted π~h92×ν~i132 two-quasiparticle band already known in the heavier 194,196,198Tl isotopes has also been found in this case based on an Iπ=8- isomeric state at 250.6 keV above the known long-lived 7+ level. Trends already noted in the other Tl isotopes and also predicted by two-quasiparticle plus-rotor model calculations are confirmed thus reinforcing such a theoretical description. NUCLEAR REACTIONS 181Ta(18O,xnγ), E=105-125 MeV; 181Ta(16O,xnγ), E=95-105 MeV; measured Eγ, Iγ, σ(E, Eγ, θγ), γ-γ coin.; 192Tl levels deduced, J, π, T12. Natural target. Ge(Li) detectors.

  12. High-spin level scheme of doubly odd 128I

    NASA Astrophysics Data System (ADS)

    Ding, B.; Wang, H. X.; Jiang, H.; Zhang, Y. H.; Zhou, X. H.; Zhao, Y. M.; Wang, S. T.; Liu, M. L.; Li, G. S.; Zheng, Y.; Zhang, N. T.; Zhou, H. B.; Ma, Y. J.; Sasakiz, Y.; Yamada, K.; Ohshima, H.; Yokose, S.; Ishizuka, M.; Komatsubara, T.; Furuno, K.

    2012-09-01

    High-spin states in the odd-odd 128I have been studied experimentally using the 124Sn(7Li, 3nγ)128I reaction at beam energies of 28 and 32 MeV. A level scheme built on the known T1/2=175 ns, (6-) isomer has been established. The low-lying states in the level scheme have been proposed to be associated with the πd5/2⊗νh11/2 and πg7/2⊗νh11/2 two-quasiparticle excitations. The strongly populated negative-parity states, forming a bandlike structure, have been assigned to be based on the πg7/2⊗νh11/2 configuration. The πh11/2⊗νh11/2 multiplet 9+, 10+, and 11+ members have been identified according to the systematics of the corresponding level structures observed in the lighter odd-odd iodine isotopes. The two-quasiparticle configuration assignments are supported by the nucleon pair approximation and empirical shell-model calculations.

  13. A new high-spin isomer in 195Bi

    NASA Astrophysics Data System (ADS)

    Roy, T.; Mukherjee, G.; Madhavan, N.; Rana, T. K.; Bhattacharya, Soumik; Asgar, Md. A.; Bala, I.; Basu, K.; Bhattacharjee, S. S.; Bhattacharya, C.; Bhattacharya, S.; Bhattacharyya, S.; Gehlot, J.; Ghugre, S. S.; Gurjar, R. K.; Jhingan, A.; Kumar, R.; Muralithar, S.; Nath, S.; Pai, H.; Palit, R.; Raut, R.; Singh, R. P.; Sinha, A. K.; Varughese, T.

    2015-11-01

    A new high-spin isomer has been identified in 195Bi at the focal plane of the HYbrid Recoil mass Analyser (HYRA) used in the gas-filled mode. The fusion evaporation reactions 169Tm (30Si, x n) 193, 195Bi were used with the beam energies on targets of 168 and 146MeV for 6n and 4n channels, respectively. The evaporation residues, separated from the fission fragments, and their decays were detected at the focal plane of HYRA using MWPC, Si-Pad and clover HPGe detectors. The half-life of the new isomer in 195Bi has been measured to be 1.6(1)μs. The configuration of the new isomer has been proposed and compared with the other isomers in this region. The Total Routhian Surface (TRS) calculations for the three-quasiparticle configurations corresponding to the new isomer suggest an oblate deformation for this isomeric state. The same calculations for different configurations in 195Bi and for the even-even 194Pb core indicate that the proton i 13/2 orbital has a large shape driving effect towards oblate shape in these nuclei.

  14. Observations of high spin states in {sup 179}Au

    SciTech Connect

    Carpenter, M.P.; Ahmad, I.; Blumenthal, D.J.

    1995-08-01

    As part of a current study on the properties of the {pi} i{sub 13/2} intruder state in the A = 175-190 region, we conducted an experiment at ATLAS to observe high spin states in {sup 179}Au utilizing the reaction {sup 144}Sm({sup 40}Ar,p4n) at beam energies of 207 MeV and 215 MeV. To aid in the identification of {sup 179}Au, and to filter out the large amount of events from fission by-products, the Fragment Mass Analyzer was utilized in conjunction with ten Compton-suppression germanium detectors. In total, 11 x 10{sup 6} {gamma}-{gamma} and 4 x 10{sup 5} {gamma}-recoil events were collected. By comparing {gamma}-rays in coincidence with an A = 179 recoil mass gate and {gamma}-rays in coincidence with Au K{alpha} and K{beta} X-rays, ten {gamma}-rays were identified as belonging to {sup 179}Au. Based on {gamma}-ray coincidence relationships and on comparisons with neighboring odd-A Au nuclei, we constructed a tentative level scheme and assigned a rotational-like sequence to the {pi} i{sub 13/2} proton configuration.

  15. Frequency tuning of polarization oscillations: Toward high-speed spin-lasers

    SciTech Connect

    Lindemann, Markus Gerhardt, Nils C.; Hofmann, Martin R.; Pusch, Tobias; Michalzik, Rainer

    2016-01-25

    Spin-controlled vertical-cavity surface-emitting lasers (spin-VCSELs) offer a high potential to overcome several limitations of conventional purely charged-based laser devices. Presumably, the highest potential of spin-VCSELs lies in their ultrafast spin and polarization dynamics, which can be significantly faster than the intensity dynamics in conventional devices. Here, we experimentally demonstrate polarization oscillations in spin-VCSELs with frequencies up to 44 GHz. The results show that the oscillation frequency mainly depends on the cavity birefringence, which can be tuned by applying mechanical strain to the VCSEL structure. A tuning range of about 34 GHz is demonstrated. By measuring the polarization oscillation frequency and the birefringence governed mode splitting as a function of the applied strain simultaneously, we are able to investigate the correlation between birefringence and polarization oscillations in detail. The experimental findings are compared to numerical calculations based on the spin-flip model.

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

    PubMed Central

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

    2014-01-01

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

  17. Dipole-Dipole Interactions of High-spin Paramagnetic Centers in Disordered Systems

    SciTech Connect

    Maryasov, Alexander G.; Bowman, Michael K.; Tsvetkov, Yuri D.

    2007-09-13

    Dipole-dipole interactions between distant paramagnetic centers (PCs) where at least one PC has spin S>1/2 are examined. The results provide a basis for the application of pulsed DEER or PELDOR methods to the measurement of distances between PC involving high-spin species. A projection operator technique based on spectral decomposition of the secular Hamiltonian is used to calculate EPR line splitting caused by the dipole coupling. This allows calculation of operators projecting arbitrary wavefunction onto high PC eigenstates when the eigenvectors of the Hamiltonian are not known. The effective spin vectors-that is, the expectation values for vector spin operators in the PC eigenstates-are calculated. The dependence of these effective spin vectors on the external magnetic field is calculated. There is a qualitative difference between pairs having at least one integer spin (non Karmers PC) and pairs of two half-integer (Kramers PC) spins. With the help of these effective spin vectors, the dipolar lineshape of EPR lines is calculated. Analytical relations are obtained for PCs with spin S=1/2 and 1. The dependence of Pake patterns on variations of zero field splitting, Zeeman energy, temperature and dipolar coupling are illustrated.

  18. Spin currents injected electrically and thermally from highly spin polarized Co{sub 2}MnSi

    SciTech Connect

    Pfeiffer, Alexander; Reeve, Robert M.; Kronenberg, Alexander; Jourdan, Martin; Kläui, Mathias; Hu, Shaojie; Kimura, Takashi

    2015-08-24

    We demonstrate the injection and detection of electrically and thermally generated spin currents probed in Co{sub 2}MnSi/Cu lateral spin valves. Devices with different electrode separations are patterned to measure the non-local signal as a function of the electrode spacing and we determine a relatively high effective spin polarization α of Co{sub 2}MnSi to be 0.63 and the spin diffusion length of Cu to be 500 nm at room temperature. The electrically generated non-local signal is measured as a function of temperature and a maximum signal is observed for a temperature of 80 K. The thermally generated non-local signal is measured as a function of current density and temperature in a second harmonic measurement detection scheme. We find different temperature dependences for the electrically and thermally generated non-local signals, which allows us to conclude that the temperature dependence of the signals is not just dominated by the transport in the Cu wire, but there is a crucial contribution from the different generation mechanisms, which has been largely disregarded till date.

  19. Bonding with parallel spins: high-spin clusters of monovalent metal atoms.

    PubMed

    Danovich, David; Shaik, Sason

    2014-02-18

    Bonding is a glue of chemical matter and is also a useful concept for designing new molecules. Despite the fact that electron pairing remains the bonding mechanism in the great majority of molecules, in the past few decades scientists have had a growing interest in discovering novel bonding motifs. As this Account shows, monovalent metallic atoms having exclusively parallel spins, such as (11)Li10, (11)Au10, and (11)Cu10, can nevertheless form strongly bound clusters, without having even one traditional bond due to electron pairing. These clusters, which also can be made chiral, have high magnetic moments. We refer to this type as no-pair ferromagnetic (NPFM) bonding, which characterizes the (n+1)Mn clusters, which were all predicted by theoretical computations. The small NPFM alkali clusters that have been "synthesized" to date, using cold-atom techniques, support the computational predictions. In this Account, we describe the origins of NPFM bonding using a valence bond (VB) analysis, which shows that this bonding motif arises from bound triplet electron pairs that spread over all the close neighbors of a given atom in the cluster. The bound triplet pair owes its stabilization to the resonance energy provided by the mixing of the local ionic configurations, [(3)M(↑↑)(-)]M(+) and M(+)[(3)M(↑↑)(-)], and the various excited covalent configurations (involving pz and dz(2) atomic orbitals) into the repulsive covalent structure (3)(M↑↑M) with the s(1)s(1) electronic configuration. The NPFM bond of the bound triplet is described by a resonating wave function with "in-out" and "out-in" pointing hybrids. The VB model accounts for the tendency of NPFM clusters to assume polyhedral shapes with rather high symmetry. In addition, this model explains the very steep rise of the bonding energy per atom (De/n), which starts out small in the (3)M2 dimer (<1 kcal/mol) and reaches 12-19 kcal/mol for clusters with 10 atoms. The model further predicts that usage of

  20. High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

    NASA Astrophysics Data System (ADS)

    Sirohi, Anshu; Singh, Chandan K.; Thakur, Gohil S.; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Haque, Zeba; Gupta, L. C.; Kabir, Mukul; Ganguli, Ashok K.; Sheet, Goutam

    2016-06-01

    CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (˜47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.

  1. Spin fluctuations and high-temperature superconductivity in cuprates

    NASA Astrophysics Data System (ADS)

    Plakida, Nikolay M.

    2016-12-01

    To describe the cuprate superconductors, models of strongly correlated electronic systems, such as the Hubbard or t - J models, are commonly employed. To study these models, projected (Hubbard) operators have to be used. Due to the unconventional commutation relations for the Hubbard operators, a specific kinematical interaction of electrons with spin and charge fluctuations emerges. The interaction is induced by the intraband hopping with a coupling parameter of the order of the kinetic energy of electrons W which is much larger than the antiferromagnetic exchange interaction J induced by the interband hopping. This review presents a consistent microscopic theory of spin excitations and superconductivity for cuprates where these interactions are taken into account within the Hubbard operator technique. The low-energy spin excitations are considered for the t-J model, while the electronic properties are studied using the two-subband extended Hubbard model where the intersite Coulomb repulsion V and electron-phonon interaction are taken into account.

  2. Problems and Progress in Covariant High Spin Description

    NASA Astrophysics Data System (ADS)

    Kirchbach, Mariana; Banda Guzmán, Víctor Miguel

    2016-10-01

    A universal description of particles with spins j > 1, transforming in (j, 0) ⊕ (0, j), is developed by means of representation specific second order differential wave equations without auxiliary conditions and in covariant bases such as Lorentz tensors for bosons, Lorentz-tensors with Dirac spinor components for fermions, or, within the basis of the more fundamental Weyl- Van-der-Waerden sl(2,C) spinor-tensors. At the root of the method, which is free from the pathologies suffered by the traditional approaches, are projectors constructed from the Casimir invariants of the spin-Lorentz group, and the group of translations in the Minkowski space time.

  3. On numerical nonlinear analysis of highly flexible spinning cantilevers

    NASA Technical Reports Server (NTRS)

    Utku, S.; El-Essawi, M.; Salama, M.

    1981-01-01

    The general nonlinear discretized equations of motion of spinning elastic solids and structures are derived as a set of nonlinear ordinary differential equations for the case when the strain-displacement and velocity-displacement relations are nonlinear up to the second order. It is shown that the cost of generation of such equations is proportional to the fourth power of the number of degrees of freedom. A computer program is written to automatically generate the equations for the case of spinning cantilevers with initial imperfections. The types and the number of the coordinate functions used in the trial solution are parameters of the program.

  4. Spin-Relaxation Dynamics of E' Centers at High Density in SiO2 Thin Films for Single-Spin Tunneling Force Microscopy

    NASA Astrophysics Data System (ADS)

    Ambal, K.; Payne, A.; Waters, D. P.; Williams, C. C.; Boehme, C.

    2015-08-01

    The suitability of the spin dynamics of paramagnetic silicon dangling bonds (E' centers) in high-E'-density amorphous silicon dioxide (SiO2 ) as probe spins for single-spin tunneling force microscopy (SSTFM) is studied. SSTFM is a spin-selection-rule-based scanning-probe single-spin readout concept. Following the synthesis of SiO2 thin films on (111)-oriented crystalline-silicon substrates with room-temperature stable densities of [E'] >5 ×1018 cm-3 throughout the 60-nm thin film, pulsed electron paramagnetic resonance spectroscopy is conducted on the E' centers at temperatures between T =5 K and T =70 K . The measurements reveal that the spin coherence (the transverse spin-relaxation time T2) of these centers is significantly shortened compared to low-E'-density SiO2 films and within error margins not dependent on temperature. In contrast, the spin-flip times (the longitudinal relaxation times T1) are dependent on the temperature but with much weaker dependence than low-density SiO2 , with the greatest deviations from low-density SiO2 seen for T =5 K . These results, discussed in the context of the spin-relaxation dynamics of dangling-bond states of other silicon-based disordered solids, indicate the suitability of E' centers in high-density SiO2 as probe spins for SSTFM.

  5. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    DOE PAGES

    Staszczak, A.; Wong, Cheuk-Yin

    2016-05-11

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28≤A≤52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114ℏ and 140ℏ, which follow the same (multi-particle) (multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  6. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    SciTech Connect

    Staszczak, A.; Wong, Cheuk-Yin

    2016-05-11

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28≤A≤52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114ℏ and 140ℏ, which follow the same (multi-particle) (multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  7. Doping dependence of spin excitations and its correlations with high-temperature superconductivity in iron pnictides.

    PubMed

    Wang, Meng; Zhang, Chenglin; Lu, Xingye; Tan, Guotai; Luo, Huiqian; Song, Yu; Wang, Miaoyin; Zhang, Xiaotian; Goremychkin, E A; Perring, T G; Maier, T A; Yin, Zhiping; Haule, Kristjan; Kotliar, Gabriel; Dai, Pengcheng

    2013-01-01

    High-temperature superconductivity in iron pnictides occurs when electrons and holes are doped into their antiferromagnetic parent compounds. Since spin excitations may be responsible for electron pairing and superconductivity, it is important to determine their electron/hole-doping evolution and connection with superconductivity. Here we use inelastic neutron scattering to show that while electron doping to the antiferromagnetic BaFe₂As₂ parent compound modifies the low-energy spin excitations and their correlation with superconductivity (<50 meV) without affecting the high-energy spin excitations (>100 meV), hole-doping suppresses the high-energy spin excitations and shifts the magnetic spectral weight to low-energies. In addition, our absolute spin susceptibility measurements for the optimally hole-doped iron pnictide reveal that the change in magnetic exchange energy below and above T(c) can account for the superconducting condensation energy. These results suggest that high-T(c) superconductivity in iron pnictides is associated with both the presence of high-energy spin excitations and a coupling between low-energy spin excitations and itinerant electrons.

  8. Doping dependence of spin excitations and its correlations with high-temperature superconductivity in iron pnictides

    PubMed Central

    Wang, Meng; Zhang, Chenglin; Lu, Xingye; Tan, Guotai; Luo, Huiqian; Song, Yu; Wang, Miaoyin; Zhang, Xiaotian; Goremychkin, E.A.; Perring, T.G.; Maier, T.A.; Yin, Zhiping; Haule, Kristjan; Kotliar, Gabriel; Dai, Pengcheng

    2013-01-01

    High-temperature superconductivity in iron pnictides occurs when electrons and holes are doped into their antiferromagnetic parent compounds. Since spin excitations may be responsible for electron pairing and superconductivity, it is important to determine their electron/hole-doping evolution and connection with superconductivity. Here we use inelastic neutron scattering to show that while electron doping to the antiferromagnetic BaFe2As2 parent compound modifies the low-energy spin excitations and their correlation with superconductivity (<50 meV) without affecting the high-energy spin excitations (>100 meV), hole-doping suppresses the high-energy spin excitations and shifts the magnetic spectral weight to low-energies. In addition, our absolute spin susceptibility measurements for the optimally hole-doped iron pnictide reveal that the change in magnetic exchange energy below and above Tc can account for the superconducting condensation energy. These results suggest that high-Tc superconductivity in iron pnictides is associated with both the presence of high-energy spin excitations and a coupling between low-energy spin excitations and itinerant electrons. PMID:24301219

  9. Spin Pumping in Superfluid ^3He in High Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kojima, H.; Suzuki, K.; Aoki, Y.; Yamaguchi, A.; Ishimoto, H.

    2008-03-01

    The spin flow dynamics in superfluid ^3He A1 phase in magnetic field has been studied up to 13 tesla. The apparatus consists of a large reservoir of of A1 phase in which a small enclosed chamber with a built-in differential pressure sensor is immersed. The chamber is connected to the reservoir via a superleak channel. The chamber is fabricated from Macor parts such that the residual heat leak is much reduced from those in our experiments. Our focus is on the measurement of relaxation of the induced pressure subsequent to either magnetically induced spin-polarized superflow or by electrostatic spin pumping. In general, both methods of measurement show that the relaxation time (τ) of the induced pressure tends to vanish smoothly as the transition temperature Tc2 is approached. However, the observed dependence of τ on magnetic field is different. The measured τ by the field gradient method continues to increase up to 8 tesla. On the other hand, τ measured by the spin pumping method tends to saturate to a constant between 5 and 13 tesla. The discrepancy is unexpected and not yet understood.

  10. High Efficiency Spin Flipper for the n3He Experiment

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher; n3He Collaboration

    2015-10-01

    The n3He experiment, constructed on the Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source, is designed to measure the parity violating (PV) proton asymmetry Ap in the capture reaction n +3 He -->3 H + p + 765 keV The asymmetry has an estimated value Ap ~ - 1 ×10-7 and is directly related to the weak isospin conserved couplings hρ0 and ωρ0 which are of fundamental interest in the verification of the meson exchange model of low energy NN intereactions. Data production for the n3He experiment began in February 2015 and is scheduled to continue thru December 2015 - reaching a statistical sensitivity δAp ~10-8 or better. I will discuss the spin flipper which is designed using the theory of double cosine-theta coils, and capable of flipping neutron spins with an efficiency approaching its maximum value ɛsf = 1 . I will also discuss the theory of Spin Magnetic Resonance (SMR) and how it is employed by the spin flipper to flip 60 Hz pulses of cold neutrons over a range of wavelengths.

  11. Puncture Initial Data and Evolution of Black Hole Binaries with High Speed and High Spin

    NASA Astrophysics Data System (ADS)

    Ruchlin, Ian

    This dissertation explores numerical models of the orbit, inspiral, and merger phases of black hole binaries. We focus on the astrophysically realistic case of black holes with nearly extremal spins, and on high energy black hole collisions. To study the evolution of such systems, we form puncture initial data by solving the four general relativity constraint equations using pseudospectral methods on a compactified collocation point domain. The solutions to these coupled, nonlinear, elliptic differential equations represent the desired configuration at an initial moment. They are then propagated forward through time using a set of hyperbolic evolution equations with the moving punctures approach in the BSSNOK and CCZ4 formalisms. To generate realistic initial data with reduced spurious gravitational wave content, the background ansatz is taken to be a conformal superposition of Schwarzschild or Kerr spatial metrics. We track the punctures during evolution, measure their horizon properties, extract the gravitational waveforms, and examine the merger remnant. These new initial data are compared with the well known Bowen-York solutions, producing up to an order of magnitude reduction in the initial unphysical gravitational radiation signature. We perform a collision from rest of two black holes with spins near to the extremal value, in a region of parameter space inaccessible to Bowen-York initial data. We simulate nonspinning black holes in quasi-circular orbits, and perform high energy head-on collisions of nonspinning black holes to estimate the magnitude of the radiated gravitational energy in the limit of infinite momentum. We also evolve spinning black holes in quasi-circular orbits with unequal masses and different spin orientations. These models provide insight into the dynamics and signals generated by compact binary systems. This is crucial to our understanding of many astrophysical phenomena, especially to the interpretation of gravitational waves, which

  12. First example of a high-level correlated calculation of the indirect spin-spin coupling constants involving tellurium: tellurophene and divinyl telluride.

    PubMed

    Rusakov, Yury Yu; Krivdin, Leonid B; Østerstrøm, Freja F; Sauer, Stephan P A; Potapov, Vladimir A; Amosova, Svetlana V

    2013-08-21

    This paper documents the very first example of a high-level correlated calculation of spin-spin coupling constants involving tellurium taking into account relativistic effects, vibrational corrections and solvent effects for medium sized organotellurium molecules. The (125)Te-(1)H spin-spin coupling constants of tellurophene and divinyl telluride were calculated at the SOPPA and DFT levels, in good agreement with experimental data. A new full-electron basis set, av3z-J, for tellurium derived from the "relativistic" Dyall's basis set, dyall.av3z, and specifically optimized for the correlated calculations of spin-spin coupling constants involving tellurium was developed. The SOPPA method shows a much better performance compared to DFT, if relativistic effects calculated within the ZORA scheme are taken into account. Vibrational and solvent corrections are next to negligible, while conformational averaging is of prime importance in the calculation of (125)Te-(1)H spin-spin couplings. Based on the performed calculations at the SOPPA(CCSD) level, a marked stereospecificity of geminal and vicinal (125)Te-(1)H spin-spin coupling constants originating in the orientational lone pair effect of tellurium has been established, which opens a new guideline in organotellurium stereochemistry.

  13. Highly-dispersive spin gapless semiconductors in rare-earth-element contained quaternary Heusler compounds

    NASA Astrophysics Data System (ADS)

    Xu, Guizhou; You, Yurong; Gong, Yuanyuan; Liu, Er; Xu, Feng; Wang, Wenhong

    2017-03-01

    The acquisition of high mobility electrons in the zero-gap band of spin gapless semiconductors is crucial for their practical applications in spintronic devices. In this work, we propose to design a higher dispersive band by importing the rare-earth atom into the Heusler compounds. With first principles calculations, we identify several new spin gapless semiconductor candidates in the 21-electron LiMgPdSn-type quaternary Heusler alloys of (Y, La, Lu)CoCr/FeMn(Al, Ga). Densities of states for most of them reveal large band gaps in the minority spin direction, and relatively low states near the Fermi level in the majority spin. According to the electron projected band analysis, we find the import of the rare earth atom can enhance the sp component in the band across the Fermi level, which is conducive to form a linear-dispersive band that is promising to enhance the carrier mobility of spin gapless semiconductors.

  14. Experimental investigation of shell-model excitations of 89Zr up to high spin

    NASA Astrophysics Data System (ADS)

    Saha, S.; Palit, R.; Sethi, J.; Trivedi, T.; Srivastava, P. C.; Kumar, S.; Naidu, B. S.; Donthi, R.; Jadhav, S.; Biswas, D. C.; Garg, U.; Goswami, A.; Jain, H. C.; Joshi, P. K.; Mukherjee, G.; Naik, Z.; Nag, S.; Nanal, V.; Pillay, R. G.; Saha, S.; Singh, A. K.

    2012-09-01

    Near yrast states in 89Zr were investigated up to high spin using the fusion evaporation reaction 80Se(13C, 4n) at an incident beam energy of 50 MeV. Excited levels of 89Zr have been observed up to ˜10 MeV excitation energy and spin ˜37/2ℏ using the prompt gamma spectroscopy technique with the Indian National Gamma Array (INGA). The angular distribution, directional correlation, and polarization measurements were carried out to assign the spin and parity of the newly reported states. The structures of both the positive and negative parity states up to highest spin observed in the present experiment have been compared with shell-model calculations using two recently developed residual interactions, JUN45 and jj44b. The role of proton excitations from p3/2 and f5/2 orbitals to the g9/2 orbital for the higher spin states has been discussed.

  15. Repulsively bound exciton-biexciton states in high-spin fermions in optical lattices

    SciTech Connect

    Argueelles, A.; Santos, L.

    2011-03-15

    We show that the interplay between spin-changing collisions and quadratic Zeeman coupling provides a mechanism for the formation of repulsively bound composites in high-spin fermions, which we illustrate by considering spin flips in an initially polarized hard-core one-dimensional Mott insulator of spin-3/2 fermions. We show that after the flips the dynamics is characterized by the creation of two types of exciton-biexciton composites. We analyze the conditions for the existence of these bound states and discuss their intriguing properties. In particular we show that the effective mass and stability of the composites depends nontrivially on spin-changing collisions, on the quadratic Zeeman effect, and on the initial exciton localization. Finally, we show that the composites may remain stable against inelastic collisions, opening the possibility of interesting quantum composite phases.

  16. Spin-polarized high-energy scattering of charged leptons on nucleons

    SciTech Connect

    Burkardt, Matthias; Nowak, Wolf-Dieter; MILLER, A.

    2009-01-01

    The proton is a composite object with spin one-half, understood to contain highly relativistic spin one-half quarks exchanging spin-one gluons, each possibly with significant orbital angular momenta. While their fundamental interactions are well described by Quantum ChromoDynamics (QCD), our standard theory of the strong interaction, nonperturbative calculations of the internal structure of the proton based directly on QCD are beginning to provide reliable results. Most of our present knowledge of the structure of the proton is based on experimental measurements interpreted within the rich framework of QCD. An area presently attracting intense interest, both experimental and theoretical, is the relationship between the spin of the proton and the spins and orbital angular momenta of its constituents. While remarkable progress has been made, especially in the last decade, the discovery and investigation of new concepts have revealed that much more remains to be learned. This progress i

  17. High-spin-low-spin transition in magnesiowüstite (Mg0.75,Fe0.25)O at high pressures under hydrostatic conditions

    NASA Astrophysics Data System (ADS)

    Lyubutin, I. S.; Gavriliuk, A. G.; Frolov, K. V.; Lin, J. F.; Troyan, I. A.

    2010-01-01

    The spin states of Fe2+ ions in (Mg0.75,Fe0.25)O magnesiowüstite crystals at hydrostatic pressures up to 90 GPa created in a diamond-anvil cell with helium as a pressure-transmitting medium have been investi-gated by transmission and synchrotron Mössbauer spectroscopy at room temperature. An electron transition from the high-spin (HS) state to the low-spin (LS) state (HS-LS crossover) has been observed in the pressure range of 55-70 GPa. The true HS-LS transition occurs in a narrow pressure range and the extension of the electron transition to ˜15 GPa is attributed to the effect of the nearest environment and to thermal fluctuations between the high-spin and low-spin states at finite temperatures. It has been found that the lowest pressure at which the electron HS-LS transition can occur in the Mg1 - x Fe x system is 50-55 GPa.

  18. Puncture Initial Data for Highly Spinning Black-Hole Binaries

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Accretion arguments suggest that some astrophysical black-holes will possess nearly extremal spins. It is expected that gravitational wave signals from orbiting and merging black-hole binaries will be detected by Advanced LIGO in the next few years. Accurate waveform models are needed to interpret detector data. We solve the Hamiltonian and momentum constraints of General Relativity representing two black-holes with nearly extremal spins and ultra-relativistic boosts in the puncture formalism using spectral methods in the Cactus/Einstein Toolkit framework. We use a non-conformally-flat ansatz with an attenuated superposition of two conformally rescaled Lorentz-boosted-Kerr 3-metrics and their corresponding conformal extrinsic curvatures. The initial data are evolved in time using moving punctures in the BSSN and Z4 formalisms. We compare with the standard Bowen-York conformally-flat ansatz, finding an order of magnitude smaller burst of spurious radiation.

  19. Structure of catabolite activator protein with cobalt(II) and sulfate

    SciTech Connect

    Rao, Ramya R.; Lawson, Catherine L.

    2014-04-15

    The crystal structure of E. coli catabolite activator protein with bound cobalt(II) and sulfate ions at 1.97 Å resolution is reported. The crystal structure of cyclic AMP–catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures.

  20. Cobalt(II) selective membrane electrode based on palladium(II) dichloro acetylthiophene fenchone azine.

    PubMed

    Isa, I M; Mustafar, S; Ahmad, M; Hashim, N; Ghani, S A

    2011-12-15

    A new cobalt(II) ion selective electrode based on palladium(II) dichloro acetylthiophene fenchone azine(I) has been developed. The best membrane composition is found to be 10:60:10:21.1 (I)/PVC/NaTPB/DOP (w/w). The electrode exhibits a Nerstian response in the range of 1.0 × 10(-1)-1.0 × 10(-6)M with a detection limit and slope of 8.0 × 10(-7)M and 29.6 ± 0.2 mV per decade respectively. The response time is within the range of 20-25s and can be used for a period of up to 4 months. The electrode developed reveals good selectivity for cobalt(II) and could be used in pH range of 3-7. The electrode has been successfully used in the determination of cobalt(II) in water samples.

  1. High density spin noise spectroscopy with squeezed light

    NASA Astrophysics Data System (ADS)

    Lucivero, Vito Giovanni; Jiménez-Martínez, Ricardo; Kong, Jia; Mitchell, Morgan

    2016-05-01

    Spin noise spectroscopy (SNS) has recently emerged as a powerful technique for determining physical properties of an unperturbed spin system from its power noise spectrum both in atomic and solid state physics. In the presence of a transverse magnetic field, we detect spontaneous spin fluctuations of a dense Rb vapor via Faraday rotation of an off-resonance probe beam, resulting in the excess of spectral noise at the Larmor frequency over a white photon shot-noise background. We report quantum enhancement of the signal-to-noise ratio via polarization squeezing of the probe beam up to 3dB over the full density range up to n = 1013 atoms cm-3, covering practical conditions used in optimized SNS experiments. Furthermore, we show that squeezing improves the trade-off between statistical sensitivity and systematic errors due to line broadening, a previously unobserved quantum advantage. Finally, we present a novel theoretical model on quantum limits of noise spectroscopies by defining a standard quantum limit under optimized regimes and by discussing the conditions of its overcoming due to squeezing.

  2. Collective spin 1 singlet phase in high-pressure oxygen

    PubMed Central

    Crespo, Yanier; Fabrizio, Michele; Scandolo, Sandro; Tosatti, Erio

    2014-01-01

    Oxygen, one of the most common and important elements in nature, has an exceedingly well-explored phase diagram under pressure, up to and beyond 100 GPa. At low temperatures, the low-pressure antiferromagnetic phases below 8 GPa where O2 molecules have spin S = 1 are followed by the broad apparently nonmagnetic ε phase from about 8 to 96 GPa. In this phase, which is our focus, molecules group structurally together to form quartets while switching, as believed by most, to spin S = 0. Here we present theoretical results strongly connecting with existing vibrational and optical evidence, showing that this is true only above 20 GPa, whereas the S = 1 molecular state survives up to about 20 GPa. The ε phase thus breaks up into two: a spinless ε0 (20−96 GPa), and another ε1 (8−20 GPa) where the molecules have S = 1 but possess only short-range antiferromagnetic correlations. A local spin liquid-like singlet ground state akin to some earlier proposals, and whose optical signature we identify in existing data, is proposed for this phase. Our proposed phase diagram thus has a first-order phase transition just above 20 GPa, extending at finite temperature and most likely terminating into a crossover with a critical point near 30 GPa and 200 K. PMID:25002513

  3. Spin-wave-driven high-speed domain-wall motions in soft magnetic nanotubes

    SciTech Connect

    Yang, Jaehak; Yoo, Myoung-Woo; Kim, Sang-Koog

    2015-10-28

    We report on a micromagnetic simulation study of interactions between propagating spin waves and a head-to-head domain wall in geometrically confined magnetic nanotubes. We found that incident spin waves of specific frequencies can lead to sufficiently high-speed (on the order of a few hundreds of m/s or higher) domain-wall motions in the same direction as that of the incident spin-waves. The domain-wall motions and their speed vary remarkably with the frequency and the amplitude of the incident spin-waves. High-speed domain-wall motions originate from the transfer torque of spin waves' linear momentum to the domain wall, through the partial or complete reflection of the incident spin waves from the domain wall. This work provides a fundamental understanding of the interaction of the spin waves with a domain wall in the magnetic nanotubes as well as a route to all-magnetic control of domain-wall motions in the magnetic nanoelements.

  4. Biosorption of copper(II) and cobalt(II) from aqueous solutions by crab shell particles.

    PubMed

    Vijayaraghavan, K; Palanivelu, K; Velan, M

    2006-08-01

    Biosorption of each of the heavy metals, copper(II) and cobalt(II) by crab shell was investigated in this study. The biosorption capacities of crab shell for copper and cobalt were studied at different particle sizes (0.456-1.117 mm), biosorbent dosages (1-10 g/l), initial metal concentrations (500-2000 mg/l) and solution pH values (3.5-6) in batch mode. At optimum particle size (0.767 mm), biosorbent dosage (5 g/l) and initial solution pH (pH 6); crab shell recorded maximum copper and cobalt uptakes of 243.9 and 322.6 mg/g, respectively, according to Langmuir model. The kinetic data obtained at different initial metal concentrations indicated that biosorption rate was fast and most of the process was completed within 2h, followed by slow attainment of equilibrium. Pseudo-second order model fitted the data well with very high correlation coefficients (>0.998). The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell. Among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage. The biosorbent was successfully regenerated and reused for five cycles.

  5. SU(2s+1) symmetry and nonlinear dynamics of high spin magnets

    SciTech Connect

    Kovalevsky, M.Y. Glushchenko, A.V.

    2014-10-15

    The article is devoted to the description of dynamics of magnets with arbitrary spin on the basis of the Hamiltonian formalism. The relationship of quantum states and magnetic degrees of freedom has been considered. Subalgebras of Poisson bracket of magnetic values for spin s=1/2; 1; 3/2 have been established. We have obtained non-linear dynamic equations for the normal and degenerate non-equilibrium states of high-spin magnets with the SO(3), SU(4), SU(2)×SU(2), SU(3), SO(4), SO(5) symmetries of exchange interaction. The connection between models of magnetic exchange energy and the Casimir invariants has been discussed.

  6. High performance liquid chromatography and electron spin resonance studies of some sugar-nitroxide solutions

    SciTech Connect

    Angel, J.P.; Thiery, C.; Battesti, C.; Vincent, P.; Raffi, J.

    1985-01-01

    Radicals induced by gamma irradiation of alpha-D-glucose, 1-0-methyl-alpha-D-glucose and maltose, in the solid state, have been studied by the spin-trapping method. High performance liquid chromatography of sugar-nitroxide solutions, combined with electron spin resonance analysis, revealed nine, eight and twelve discernible radical species, the majority of them being indiscernible by the direct spin-trapping method. Tentative correlations and assignments of chemical structures are discussed. 9 references, 4 figures, 3 tables.

  7. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    SciTech Connect

    Broda, R.; Wrzesinski, J.; Pawlat, T.

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  8. Coherent manipulation of an ensemble of nuclear spins in diamond for high precision rotation sensing

    NASA Astrophysics Data System (ADS)

    Jaskula, Jean-Christophe; Saha, Kasturi; Ajoy, Ashok; Cappellaro, Paola

    2016-05-01

    Gyroscopes find wide applications in everyday life from navigation and inertial sensing to rotation sensors in hand-held devices and automobiles. Current devices, based on either atomic or solid-state systems, impose a choice between long-time stability and high sensitivity in a miniaturized system. We are building a solid-state spin gyroscope associated with the Nitrogen-Vacancy (NV) centers in diamond take advantage of the efficient optical initialization and measurement offered by the NV electronic spin and the stability and long coherence time of the nuclear spin, which is preserved even at high defect density. In addition, we also investigate electro-magnetic noise monitoring and feedback schemes based on the coupling between the NV electronic and nuclear spin to achieve higher stability.

  9. Production of High Performance Bioinspired Silk Fibers by Straining Flow Spinning.

    PubMed

    Madurga, Rodrigo; Gañán-Calvo, Alfonso M; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Pérez-Rigueiro, José

    2017-03-03

    In the last years, there has been an increasing interest in bioinspired approaches for different applications, including the spinning of high performance silk fibers. Bioinspired spinning is based on the natural spinning system of spiders and worms and requires combining changes in the chemical environment of the proteins with the application of mechanical stresses. Here we present the novel straining flow spinning (SFS) process and prove its ability to produce high performance fibers under mild, environmentally friendly conditions, from aqueous protein dopes. SFS is shown to be an extremely versatile technique which allows controlling a large number of processing parameters. This ample set of parameters allows fine-tuning the microstructure and mechanical behavior of the fibers, which opens the possibility of adapting the fibers to their intended uses.

  10. High Spin Polarization at Ferromagnetic Metal-Organic Interfaces: A Generic Property.

    PubMed

    Djeghloul, Fatima; Gruber, Manuel; Urbain, Etienne; Xenioti, Dimitra; Joly, Loic; Boukari, Samy; Arabski, Jacek; Bulou, Hervé; Scheurer, Fabrice; Bertran, François; Le Fèvre, Patrick; Taleb-Ibrahimi, Amina; Wulfhekel, Wulf; Garreau, Guillaume; Hajjar-Garreau, Samar; Wetzel, Patrick; Alouani, Mebarek; Beaurepaire, Eric; Bowen, Martin; Weber, Wolfgang

    2016-07-07

    A high spin polarization of states around the Fermi level, EF, at room temperature has been measured in the past at the interface between a few molecular candidates and the ferromagnetic metal Co. Is this promising property for spintronics limited to these candidates? Previous reports suggested that certain conditions, such as strong ferromagnetism, i.e., a fully occupied spin-up d band of the ferromagnet, or the presence of π bonds on the molecule, i.e., molecular conjugation, needed to be met. What rules govern the presence of this property? We have performed spin-resolved photoemission spectroscopy measurements on a variety of such interfaces. We find that this property is robust against changes to the molecule and ferromagnetic metal's electronic properties, including the aforementioned conditions. This affirms the generality of highly spin-polarized states at the interface between a ferromagnetic metal and a molecule and augurs bright prospects toward integrating these interfaces within organic spintronic devices.

  11. Cobalt(II) Porphyrin-Catalyzed Intramolecular Cyclopropanation of N-Alkyl Indoles/Pyrroles with Alkylcarbene: Efficient Synthesis of Polycyclic N-Heterocycles.

    PubMed

    Reddy, Annapureddy Rajasekar; Hao, Fei; Wu, Kai; Zhou, Cong-Ying; Che, Chi-Ming

    2016-01-26

    A protocol on chemoselective cobalt(II) porphyrin-catalyzed intramolecular cyclopropanation of N-alkyl indoles/pyrroles with alkylcarbenes has been developed. The reaction enables the rapid construction of a range of nitrogen-containing polycyclic compounds in moderate to high yields from readily accessible materials. These N-containing polycyclic compounds can be converted into a variety of N-heterocycles with potential synthetic and biological interest. Compared to their N-tosylhydrazone counterparts, the use of bulky N-2,4,6-triisopropylbenzenesulfonyl hydrazones as carbene precursors allows cyclopropanation to occur under milder reaction conditions.

  12. The Spin Contribution to the pp-TOTAL Cross-Section at High Energy

    NASA Astrophysics Data System (ADS)

    Andreeva, E. A.; Strikhanov, M. N.; Nurushev, S. B.

    The experimental data on the pp-total cross-sections including the spin-dependent parts are analyzed with the goal to determine the contribution of spin interactions at high energies. Based on the Regge model with cuts, the energy dependencies of such contributions are estimated for two spin-dependent terms: (1) the total spin dependent term, σ1 and (2) the spin projection dependent term, σ2. The estimates show that their contributions to the unpolarized total cross section, σ0, decrease with energy from several % around 2 GeV/c to 10-2% around 200 GeV/c. The assumption σ1= -σ2 does not seem to be correct, while the hypothesis 3 σ1=-σ2 is more preferable, especially in the measured energy interval 2-6 GeV. There is a clear indication that the spin effects are sensitive to the pomeron intercept at - t=0 (GeV/c)2. In order to pin down such effects the spin dependent total cross-sections must be measured with precisions better than 10 μb at 200 GeV/c.

  13. gamma-Tocotrienol modulates the paracrine secretion of VEGF induced by cobalt(II) chloride via ERK signaling pathway in gastric adenocarcinoma SGC-7901 cell line.

    PubMed

    Bi, Sheng; Liu, Jia-Ren; Li, Yang; Wang, Qi; Liu, Hui-Kun; Yan, Ya-Geng; Chen, Bing-Qing; Sun, Wen-Guang

    2010-01-01

    Hypoxia is a common characteristic feature of solid tumors, and carcinoma cells are known to secrete many growth factors. These growth factors, such as vascular endothelial growth factor (VEGF), play a major role in the regulation of tumor angiogenesis and metastasis. In this study, the effect of gamma-tocotrienol, a natural product commonly found in palm oil and rice bran, on the accumulation of HIF-1alpha protein and the paracrine secretion of VEGF in human gastric adenocarcinoma SGC-7901 cell line induced by cobalt(II) chloride (as a hypoxia mimic) was investigated. These results showed that cobalt(II) chloride induced the high expression of VEGF in SGC-7901 cells at dose of 150 micromol/L for 24h. Both basal level and cobalt(II) chloride-induced HIF-1alpha protein accumulation and VEGF paracrine secretion were inhibited in SGC-7901 cells treated with gamma-tocotrienol at 60 micromol/L treatment for 24 h. U0126, a MEK1/2 inhibitor, decreased the expression of HIF-1alpha protein and the paracrine secretion of VEGF under normoxic and hypoxic conditions. In this study, gamma-tocotrienol also significantly inhibited the hypoxia-stimulated expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2). The mechanism seems to involve in inhibiting hypoxia-mediated activation of p-ERK1/2, it leads to a marked decrease in hypoxia-induced HIF-1alpha protein accumulation and VEGF secretion. These data suggest that HIF-1alpha/VEGF could be a promising target for gamma-tocotrienol in an effective method of chemoprevention and chemotherapy in human gastric cancer.

  14. Use of high observing power in electron spin resonance saturation-recovery experiments in spin-labeled membranes

    NASA Astrophysics Data System (ADS)

    Yin, Jun-Jie; Hyde, James S.

    1989-11-01

    Biomolecular collision rates of 14N-containing nitroxide radical labeled stearic acid with similar 15N-containing species in dimyristoylphosphatidylcholine (DMPC) liposomes have been determined using the saturation-recovery electron spin resonance (ESR) method. It is shown that high microwave observing powers can be used to obtain these rates, thereby increasing the signal-to-noise ratio by about ten times relative to methods previously used. The data are analyzed using the rate-equation approach with inclusion of the observing transition probability. A number of solutions to these equations for other experimental situations and for pulse and continuous wave electron-electron double resonance (ELDOR) are also presented. The bimolecular collision rate of labels at the C16 position was found to be 20% greater than for labels at the C12 position, suggesting that the interaction distance differs at these two positions. Even though the high observing power does not affect the ability to extract bimolecular collision rates, the effective spin-lattice relaxation rates are altered. Plots of these latter rates versus power are linear and the slope can be used to determine the absolute microwave field at the sample for a given input power.

  15. Ferrimagnetic and Long Period Antiferromagnetic Phases in High Spin Heisenberg Chains with D-Modulation

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2007-02-01

    The ground state properties of the high spin Heisenberg chains with alternating single site anisotropy are investigated by means of the numerical exact daigonaization and DMRG method. It is found that the ferrimagnetic state appears between the Haldane phase and period doubled Néel phase for the integer spin chains. On the other hand, the transition from the Tomonaga-Luttinger liquid state into the ferrimagnetic state takes place for the half-odd-integer spin chains. In the ferrimagnetic phase, the spontaneous magnetization varies continuously with the modulation amplitude of the single site anisotropy. Eventually, the magnetization is locked to fractional values of the saturated magnetization. These fractional values satisfy the Oshikawa-Yamanaka-Affleck condition. The local spin profile is calculated to reveal the physical nature of each state. In contrast to the case of frustration induced ferrimagnetism, no incommensurate magnetic superstructure is found.

  16. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment.

    PubMed

    Holley, A T; Broussard, L J; Davis, J L; Hickerson, K; Ito, T M; Liu, C-Y; Lyles, J T M; Makela, M; Mammei, R R; Mendenhall, M P; Morris, C L; Mortensen, R; Pattie, R W; Rios, R; Saunders, A; Young, A R

    2012-07-01

    The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be ̅ε=0.9985(4).

  17. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

    NASA Astrophysics Data System (ADS)

    Holley, A. T.; Broussard, L. J.; Davis, J. L.; Hickerson, K.; Ito, T. M.; Liu, C.-Y.; Lyles, J. T. M.; Makela, M.; Mammei, R. R.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R.; Pattie, R. W.; Rios, R.; Saunders, A.; Young, A. R.

    2012-07-01

    The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be overline{ɛ }=0.9985(4).

  18. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    DOEpatents

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  19. Nuclear structure and high-spin states of 137Pr

    NASA Astrophysics Data System (ADS)

    Dragulescu, E.; Ivascu, M.; Petrache, C.; Popescu, D.; Semenescu, G.; Gurgu, I.; Ionescu-Bujor, M.; Iordachescu, A.; Pascovici, G.; Meyer, R. A.; Lopac, V.; Brant, S.; Paar, V.; Vorkapić, D.; Vretenar, D.

    1992-10-01

    Levels in 137Pr were populated in the 126Te( 14N, 3n) and 122Sn( 19F, 4n) reactions and the subsequent radiation was studied using in-beam γ-ray spectroscopy methods including γ-ray excitation-function, angular-distribution, γγ( t) coincidence and γ( t) measurements. A level scheme with new states up to spin {35}/{2} belonging to 137Pr is given. The lifetime of the {11}/{21} state at 563.4 keV has been determined as T {1}/{2} = 2.66±0.07 μ s. The calculation of low-lying levels in 137Pr performed in IBFM has been compared to experimental data.

  20. Natural reference for nuclear high-spin states

    SciTech Connect

    Rowley, Neil; Ollier, James; Simpson, John

    2009-08-15

    We suggest two new representations of the data on rotational nuclei. The first is reference-free and the second arises from a natural reference related to the variable moment of inertia model parameters of the ground-state band of the system. As such, neither representation contains any free parameters. By defining a 'configuration spin' we show how a new ground-state band reference can be applied. Its use allows a complete description of the changes associated with the first, and higher, band crossings. We apply these new representations to discuss the nature of the first band crossing along even-even isotopic chains in the erbium and osmium isotopes and to odd-even nuclei in the vicinity of {sup 158}Er.

  1. Highly stable atomic vector magnetometer based on free spin precession.

    PubMed

    Afach, S; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Grujić, Z D; Hayen, L; Hélaine, V; Kasprzak, M; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Naviliat-Cuncic, O; Piegsa, F M; Prashanth, P N; Quéméner, G; Rawlik, M; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severjins, N; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zsigmond, G

    2015-08-24

    We present a magnetometer based on optically pumped Cs atoms that measures the magnitude and direction of a 1 μT magnetic field. Multiple circularly polarized laser beams were used to probe the free spin precession of the Cs atoms. The design was optimized for long-time stability and achieves a scalar resolution better than 300 fT for integration times ranging from 80 ms to 1000 s. The best scalar resolution of less than 80 fT was reached with integration times of 1.6 to 6 s. We were able to measure the magnetic field direction with a resolution better than 10 μrad for integration times from 10 s up to 2000 s.

  2. Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure

    NASA Astrophysics Data System (ADS)

    Wang, Shuanhu; Zou, Lvkuan; Zhang, Xu; Cai, Jianwang; Wang, Shufang; Shen, Baogen; Sun, Jirong

    2015-10-01

    Based on unique experimental setups, the temperature dependences of the longitudinal spin Seebeck effect (LSSE) and spin Hall magnetoresistance (SMR) of the Pt/yttrium iron garnet (Pt/YIG) hybrid structure are determined in a wide temperature range up to the Curie temperature of YIG. From a theoretical analysis of the experimental relationship between the SMR and temperature, the spin mixing conductance of the Pt/YIG interface is deduced as a function of temperature. Adopting the deduced spin mixing conductance, the temperature dependence of the LSSE is well reproduced based on the magnon spin current theory. Our research sheds new light on the controversy about the theoretical models for the LSSE.

  3. Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure.

    PubMed

    Wang, Shuanhu; Zou, Lvkuan; Zhang, Xu; Cai, Jianwang; Wang, Shufang; Shen, Baogen; Sun, Jirong

    2015-11-14

    Based on unique experimental setups, the temperature dependences of the longitudinal spin Seebeck effect (LSSE) and spin Hall magnetoresistance (SMR) of the Pt/yttrium iron garnet (Pt/YIG) hybrid structure are determined in a wide temperature range up to the Curie temperature of YIG. From a theoretical analysis of the experimental relationship between the SMR and temperature, the spin mixing conductance of the Pt/YIG interface is deduced as a function of temperature. Adopting the deduced spin mixing conductance, the temperature dependence of the LSSE is well reproduced based on the magnon spin current theory. Our research sheds new light on the controversy about the theoretical models for the LSSE.

  4. Loss of collectivity in the transitional {sup 156}Er nucleus at high spin

    SciTech Connect

    Paul, E. S.; Rigby, S. V.; Choy, P. T. W.; Evans, A. O.; Nolan, P. J.; Riley, M. A.; Campbell, D. B.; Pipidis, A.; Simpson, J.; Appelbe, D. E.; Joss, D. T.; Clark, R. M.; Cromaz, M.; Fallon, P.; Goergen, A.; Lee, I. Y.; Macchiavelli, A. O.; Ward, D.; Ragnarsson, I.

    2009-04-15

    The {sup 114}Cd({sup 48}Ca,6n{gamma}) reaction at 215 MeV has been investigated using the Gammasphere spectrometer to study the high-spin structure of the nucleus {sub 68}{sup 156}Er{sub 88}. Many new transitions have been established along with definitive spin-parity level assignments from a high-fold angular-distribution analysis. In addition, absolute B(M1) and B(E1) strengths have been inferred from measured {gamma}-ray branching ratios. Strong B(E1) strength (10{sup -3} W.u.) is discussed in terms of possible octupole collectivity at low spin. At high spin, this nucleus undergoes a Coriolis-induced shape transition from a prolate state of collective rotation to a noncollective, triaxial-oblate configuration. The yrast positive-parity structure ultimately terminates in an energetically favored oblate state at I{sup {pi}}=42{sup +}. Several weak high-energy {gamma}-ray transitions have been discovered that feed this favored state. State-of-the-art cranked Nilsson-Strutinsky calculations are used to interpret the high-spin behavior of {sup 156}Er and comparisons are made with other N=88 isotones.

  5. Triaxiality and Exotic Rotations at High Spins in 134Ce

    SciTech Connect

    Petrache, C. M.; Garg, U.; Matta, J. T.; Nayak, B. K.; Patel, D.; Carpenter, M. P.; Chiara, C. J.; Janssens, R. V. F.; Kondev, F. G.; Lauritsen, T.; Seweryniak, D.; Zhu, S.; Ghugre, S. S.; Palit, R.

    2016-06-06

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

  6. Spin blockade and coherent dynamics of high-spin states in a three-electron double quantum dot

    NASA Astrophysics Data System (ADS)

    Chen, Bao-Bao; Wang, Bao-Chuan; Cao, Gang; Li, Hai-Ou; Xiao, Ming; Guo, Guang-Can; Jiang, Hong-Wen; Hu, Xuedong; Guo, Guo-Ping

    2017-01-01

    Asymmetry in a three-electron double quantum dot (DQD) allows spin blockade, when spin-3/2 (quadruplet) states and spin-1/2 (doublet) states have different charge configurations. We have observed this DQD spin blockade near the (1,2)-(2,1) charge transition using a pulsed-gate technique and a charge sensor. We, then, use this spin blockade to detect Landau-Zener-Stückelberg interference and coherent oscillations between the spin quadruplet and doublet states. Such studies add to our understandings of coherence and control properties of three-spin states in a double dot, which, in turn, would benefit explorations into various qubit encoding schemes in semiconductor nanostructures.

  7. Scalable fabrication of high purity diamond nanocrystals with long-spin-coherence nitrogen vacancy centers.

    PubMed

    Trusheim, Matthew E; Li, Luozhou; Laraoui, Abdelghani; Chen, Edward H; Bakhru, Hassaram; Schröder, Tim; Gaathon, Ophir; Meriles, Carlos A; Englund, Dirk

    2014-01-08

    The combination of long spin coherence time and nanoscale size has made nitrogen vacancy (NV) centers in nanodiamonds the subject of much interest for quantum information and sensing applications. However, currently available high-pressure high-temperature (HPHT) nanodiamonds have a high concentration of paramagnetic impurities that limit their spin coherence time to the order of microseconds, less than 1% of that observed in bulk diamond. In this work, we use a porous metal mask and a reactive ion etching process to fabricate nanocrystals from high-purity chemical vapor deposition (CVD) diamond. We show that NV centers in these CVD nanodiamonds exhibit record-long spin coherence times in excess of 200 μs, enabling magnetic field sensitivities of 290 nT Hz(-1/2) with the spatial resolution characteristic of a 50 nm diameter probe.

  8. A High-Spin Rate Measurement Method for Projectiles Using a Magnetoresistive Sensor Based on Time-Frequency Domain Analysis.

    PubMed

    Shang, Jianyu; Deng, Zhihong; Fu, Mengyin; Wang, Shunting

    2016-06-16

    Traditional artillery guidance can significantly improve the attack accuracy and overall combat efficiency of projectiles, which makes it more adaptable to the information warfare of the future. Obviously, the accurate measurement of artillery spin rate, which has long been regarded as a daunting task, is the basis of precise guidance and control. Magnetoresistive (MR) sensors can be applied to spin rate measurement, especially in the high-spin and high-g projectile launch environment. In this paper, based on the theory of a MR sensor measuring spin rate, the mathematical relationship model between the frequency of MR sensor output and projectile spin rate was established through a fundamental derivation. By analyzing the characteristics of MR sensor output whose frequency varies with time, this paper proposed the Chirp z-Transform (CZT) time-frequency (TF) domain analysis method based on the rolling window of a Blackman window function (BCZT) which can accurately extract the projectile spin rate. To put it into practice, BCZT was applied to measure the spin rate of 155 mm artillery projectile. After extracting the spin rate, the impact that launch rotational angular velocity and aspect angle have on the extraction accuracy of the spin rate was analyzed. Simulation results show that the BCZT TF domain analysis method can effectively and accurately measure the projectile spin rate, especially in a high-spin and high-g projectile launch environment.

  9. A High-Spin Rate Measurement Method for Projectiles Using a Magnetoresistive Sensor Based on Time-Frequency Domain Analysis

    PubMed Central

    Shang, Jianyu; Deng, Zhihong; Fu, Mengyin; Wang, Shunting

    2016-01-01

    Traditional artillery guidance can significantly improve the attack accuracy and overall combat efficiency of projectiles, which makes it more adaptable to the information warfare of the future. Obviously, the accurate measurement of artillery spin rate, which has long been regarded as a daunting task, is the basis of precise guidance and control. Magnetoresistive (MR) sensors can be applied to spin rate measurement, especially in the high-spin and high-g projectile launch environment. In this paper, based on the theory of a MR sensor measuring spin rate, the mathematical relationship model between the frequency of MR sensor output and projectile spin rate was established through a fundamental derivation. By analyzing the characteristics of MR sensor output whose frequency varies with time, this paper proposed the Chirp z-Transform (CZT) time-frequency (TF) domain analysis method based on the rolling window of a Blackman window function (BCZT) which can accurately extract the projectile spin rate. To put it into practice, BCZT was applied to measure the spin rate of 155 mm artillery projectile. After extracting the spin rate, the impact that launch rotational angular velocity and aspect angle have on the extraction accuracy of the spin rate was analyzed. Simulation results show that the BCZT TF domain analysis method can effectively and accurately measure the projectile spin rate, especially in a high-spin and high-g projectile launch environment. PMID:27322266

  10. The Excitation of High Spin States with Quasielastic and Deep Inelastic Reactions.

    NASA Astrophysics Data System (ADS)

    Knott, Clinton Neal

    1988-12-01

    The feasibility of populating high spin states using reactions induced by a 220 MeV ^{22 }Ne beam on a ^{170} Er target was studied. The experiment was carried out using a multidetector array for high resolution gamma-ray spectroscopy, a 14 element sum multiplicity spectrometer and six DeltaE-E particle telescopes. Detailed information was obtained concerning the reaction mechanisms associated with various reaction channels. Deep inelastic collisions are shown to be a promising tool for high spin spectroscopy in regions of the chart of nuclides which are not accessible by other reactions.

  11. Population of high spin states by quasi-elastic and deep inelastic collisions

    NASA Astrophysics Data System (ADS)

    Takai, H.; Knott, C. N.; Winchell, D. F.; Saladin, J. X.; Kaplan, M. S.; de Faro, L.; Aryaeinejad, R.; Blue, R. A.; Ronningen, R. M.; Morrissey, D. J.; Lee, I. Y.; Dietzsch, O.

    1988-09-01

    The feasibility of populating high spin states using reactions induced by a 10 MeV/nucleon 22Ne beam on 170Er was studied. The experiment was carried out using a multidetector array for high resolution γ-ray spectroscopy, a 14 element sum-multiplicity spectrometer and six ΔE-E telescopes. Detailed information was obtained concerning the reaction mechanisms associated with various reaction channels. Deep inelastic collisions are shown to be a promising tool for high spin spectroscopy in regions of the chart of nuclides which are not accessible by other reactions.

  12. The excitation of high spin states with quasi-elastic and deep inelastic reactions

    SciTech Connect

    Knott, C.N.

    1988-01-01

    The feasibility of populating high spin states using reactions induced by a 220 MeV {sup 22}Ne beam on a {sup 170}Er target was studied. The experiment was carried out using a multidetector array for high resolution {gamma}-ray spectroscopy, a 14 element sum multiplicity spectrometer and six {Delta}E-E particle telescopes. Detailed information was obtained concerning the reaction mechanisms associated with various reaction channels. Deep inelastic collisions are shown to be a promising tool for high spin spectroscopy in regions of the chart of nuclides which are not accessible by other reactions.

  13. Population of high spin states by quasi-elastic and deep inelastic collisions

    SciTech Connect

    Takai, H.; Knott, C.N.; Winchell, D.F.; Saladin, J.X.; Kaplan, M.S.; de Faro, L.; Aryaeinejad, R.; Blue, R.A.; Ronningen, R.M.; Morrissey, D.J.; and others

    1988-09-01

    The feasibility of populating high spin states using reactions induced by a 10 MeV/nucleon /sup 22/Ne beam on /sup 170/Er was studied. The experiment was carried out using a multidetector array for high resolution ..gamma..-ray spectroscopy, a 14 element sum-multiplicity spectrometer and six ..delta..E-E telescopes. Detailed information was obtained concerning the reaction mechanisms associated with various reaction channels. Deep inelastic collisions are shown to be a promising tool for high spin spectroscopy in regions of the chart of nuclides which are not accessible by other reactions.

  14. Cross-shell excitations in {sup 30}Al and {sup 30}Si at high spin.

    SciTech Connect

    Steppenbeck, D.; Deacon, A. N.; Freeman, S. J.; Janssens, R. V .F.; Carpenter, M. P.; Hoffman, C. R.; Kay, B. P.; Lauritsen, T.; Lister, C. J.; O'Donnell, D.; Ollier, J.; Seweryniak, D.; Smith, J. F.; Spohr, K.-M.; Tabor, S. L.; Tripathi, V.; Wady, P. T.; Zhu, S.

    2010-12-01

    Yrast and near-yrast states in {sup 30}Al and {sup 30}Si have been populated to high spin with the {sup 18}O + {sup 14}C fusion-evaporation reaction in inverse kinematics. The level schemes for these two isobars have been extended up to J {approx} 9 {h_bar} at 9.4 and 15.5 MeV, respectively. Their decay schemes indicate that cross-shell excitations dominate at high spin, where negative-parity structures exist. Positive-parity states are compared to the results of shell-model calculations using the USD, USDA, and USDB effective interactions. The negative-parity levels are compared to predictions of the WBP interaction and the recently-developed WBP-a Hamiltonian, by allowing 1p-1h excitations to fp-shell orbitals. The results suggest that single-neutron excitations to the 0f7/2 orbital play a significant role at high spin.

  15. Spectroscopy and high-spin structure of {sup 209}Fr

    SciTech Connect

    Dracoulis, G. D.; Davidson, P. M.; Lane, G. J.; Kibedi, T.; Nieminen, P.; Watanabe, H.; Byrne, A. P.; Wilson, A. N.

    2009-05-15

    Excited states in {sup 209}Fr have been studied using the {sup 197}Au({sup 16}O,4n){sup 209}Fr reaction with pulsed beams and {gamma}-ray and electron spectroscopy. A comprehensive scheme has been established up to an excitation energy of about 6 MeV and spins of about 49/2({Dirac_h}/2{pi}). Several isomers have been identified including a J{sup {pi}}=25/2{sup +}, {tau}=48(3) ns state at 2130 keV and a 606(26) ns, 45/2{sup -} state at 4660 keV. The latter state decays via an enhanced E3 transition with a strength of 28.8(12) W.u. It can be identified with a similar isomer in the heavier odd isotopes {sup 211}Fr and {sup 213}Fr, arising from the maximal coupling of the five valence protons in the {pi}h{sub 9/2}{sup 3}i{sub 13/2}{sup 2} configuration. The systematics of the yrast states in the odd-A isotopes are discussed, including the presence of states arising from the main proton configurations coupled to the p{sub 1/2}, f{sub 5/2}, and i{sub 13/2} neutron holes. Shell-model configurations are assigned to many of the observed states. The isotopic assignment differs from earlier work, which is shown to be erroneous.

  16. High-spin states in 29Al and 27Mg

    NASA Astrophysics Data System (ADS)

    Dungan, R.; Tabor, S. L.; Lubna, R. S.; Volya, A.; Tripathi, Vandana; Abromeit, B.; Caussyn, D. D.; Kravvaris, K.; Tai, P.-L.

    2016-12-01

    The structure of 29Al and 27Mg was investigated using the reactions 18O(14C,p 2 n ) and 18O(14C,α n ) at 40 MeV. The charged particles were detected and identified with a Δ E -E telescope in coincidence with γ radiation detected in the Florida State University Compton suppressed γ detector array. The level and decay schemes of both nuclei have been expanded at higher spins and excitation energies. The positive-parity states up to 3.5-4.5 MeV agree well with shell model calculations using the USDA interaction. The negative-parity states in 27Mg are reproduced relatively well by one-particle-one-hole calculations with the WBP-a interaction. Three 27Mg states unbound by 0.4-1.4 MeV to neutron decay were observed to decay radiatively. One of these states had been previously observed to γ decay in a (d ,p γ ) experiment along with a surprising 16 other neutron unbound states. The competition between neutron and γ decay in these states is discussed in terms of angular momentum barriers and spectroscopic factors.

  17. High-fidelity gates in quantum dot spin qubits

    PubMed Central

    Koh, Teck Seng; Coppersmith, S. N.; Friesen, Mark

    2013-01-01

    Several logical qubits and quantum gates have been proposed for semiconductor quantum dots controlled by voltages applied to top gates. The different schemes can be difficult to compare meaningfully. Here we develop a theoretical framework to evaluate disparate qubit-gating schemes on an equal footing. We apply the procedure to two types of double-dot qubits: the singlet–triplet and the semiconducting quantum dot hybrid qubit. We investigate three quantum gates that flip the qubit state: a DC pulsed gate, an AC gate based on logical qubit resonance, and a gate-like process known as stimulated Raman adiabatic passage. These gates are all mediated by an exchange interaction that is controlled experimentally using the interdot tunnel coupling g and the detuning ϵ, which sets the energy difference between the dots. Our procedure has two steps. First, we optimize the gate fidelity (f) for fixed g as a function of the other control parameters; this yields an that is universal for different types of gates. Next, we identify physical constraints on the control parameters; this yields an upper bound that is specific to the qubit-gate combination. We show that similar gate fidelities should be attainable for singlet-triplet qubits in isotopically purified Si, and for hybrid qubits in natural Si. Considerably lower fidelities are obtained for GaAs devices, due to the fluctuating magnetic fields ΔB produced by nuclear spins. PMID:24255105

  18. A high field optical-pumping spin-exchange polarized deuterium source

    SciTech Connect

    Coulter, K.P.; Holt, R.J.; Kinney, E.R.; Kowalczyk, R.S.; Poelker, M.; Potterveld, D.H.; Young, L.; Zeidman, B. ); Toporkov, D. . Inst. Yadernoj Fiziki)

    1992-01-01

    Recent results from a prototype high field optical-pumping spin-exchange polarized deuterium source are presented. Atomic polarization as high as 62% have been observed with an intensity of 6.3 [times] 10[sup 17] atoms-sec[sup [minus]1] and 65% dissociation fraction.

  19. Signatures of chaos in time series generated by many-spin systems at high temperatures.

    PubMed

    Elsayed, Tarek A; Hess, Benjamin; Fine, Boris V

    2014-08-01

    Extracting reliable indicators of chaos from a single experimental time series is a challenging task, in particular, for systems with many degrees of freedom. The techniques available for this purpose often require unachievably long time series. In this paper, we explore a method of discriminating chaotic from multi-periodic integrable motion in many-particle systems. The applicability of this method is supported by our numerical simulations of the dynamics of classical spin lattices at high temperatures. We compared chaotic and nonchaotic regimes of these lattices and investigated the transition between the two. The method is based on analyzing higher-order time derivatives of the time series of a macroscopic observable-the total magnetization of the spin lattice. We exploit the fact that power spectra of the magnetization time series generated by chaotic spin lattices exhibit exponential high-frequency tails, while, for the integrable spin lattices, the power spectra are terminated in a non-exponential way. We have also demonstrated the applicability limits of the above method by investigating the high-frequency tails of the power spectra generated by quantum spin lattices and by the classical Toda lattice.

  20. Femtosecond time-resolved optical and Raman spectroscopy of photoinduced spin crossover: temporal resolution of low-to-high spin optical switching.

    PubMed

    Smeigh, Amanda L; Creelman, Mark; Mathies, Richard A; McCusker, James K

    2008-10-29

    A combination of femtosecond electronic absorption and stimulated Raman spectroscopies has been employed to determine the kinetics associated with low-spin to high-spin conversion following charge-transfer excitation of a FeII spin-crossover system in solution. A time constant of tau = 190 +/- 50 fs for the formation of the 5T2 ligand-field state was assigned based on the establishment of two isosbestic points in the ultraviolet in conjunction with changes in ligand stretching frequencies and Raman scattering amplitudes; additional dynamics observed in both the electronic and vibrational spectra further indicate that vibrational relaxation in the high-spin state occurs with a time constant of ca. 10 ps. The results set an important precedent for extremely rapid, formally forbidden (DeltaS = 2) nonradiative relaxation as well as defining the time scale for intramolecular optical switching between two electronic states possessing vastly different spectroscopic, geometric, and magnetic properties.

  1. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  2. IBFA description of high-spin positive-parity states in Rh isotopes

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Cǎta, G.; Cutoiu, D.; Constantinescu, G.; Ivascu, M.; Zamfir, N. V.

    1985-09-01

    Properties of the odd-mass Rh isotopes are investigated in the framework of the interacting boson-fermion approximation (IBFA) model in which the odd proton movea in the 1 g{9}/{2} and 2 d{5}/{2} orbitals. Lifetimes of some high-spin positive-parity states in 99Rh obtained by the recoil-distance method with the 88Sr( 14N, 3n) reaction are also reported. Calculated excitation energies and electromagnetic properties of the high-spin positive-parity states are compared with experiment and an acceptable agreement is obtained.

  3. Shape evolution at high spin states in Kr and Br isotopes

    SciTech Connect

    Trivedi, T.; Palit, R.; Naik, Z.; Jain, H. C.; Negi, D.; Kumar, R.; Singh, R. P.; Muralithar, S.; Pancholi, S. C.; Bhowmik, R. K.; Yang, Y.-C.; Sun, Y.; Sheikh, J. A.; Raja, M. K.; Kumar, S.; Choudhury, D.; Jain, A. K.; Mehrotra, I.

    2014-08-14

    The high spin states in A = 75, Kr and Br isotopes have been populated via fusion-evaporation reaction at an incident beam energy of 90 MeV. The de-exciting γ-rays were detected utilizing the Indian National Gamma Array (INGA). Lifetime of these excited high spin states were determined by Doppler-shift attenuation method. Experimental results obtained from lifetime measurement are interpreted in the frame work of projected shell-model to get better insight into the evolution of collectivity. Comparison of the calculations of the model with transitional quadrupole moments Q{sub t} of the positive and negative parity bands firmly established their configurations.

  4. Rotor design for high pressure magic angle spinning nuclear magnetic resonance.

    PubMed

    Turcu, Romulus V F; Hoyt, David W; Rosso, Kevin M; Sears, Jesse A; Loring, John S; Felmy, Andrew R; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low (1)H and (13)C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe(2+))(3)Si(2)O(5)(OH)(4)), in contact with liquid water in water-saturated supercritical CO(2) (scCO(2)) at 150 bar and 50°C. This mineral is relevant to the deep geologic disposal of CO(2), but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  5. Rotor design for high pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Turcu, Romulus V. F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 °C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  6. Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance

    SciTech Connect

    Turcu, Romulus V.F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Z.

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 deg C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  7. High-fidelity transfer and storage of photon states in a single nuclear spin

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Wang, Ya; Rao, D. D. Bhaktavatsala; Hien Tran, Thai; Momenzadeh, Ali S.; Markham, M.; Twitchen, D. J.; Wang, Ping; Yang, Wen; Stöhr, Rainer; Neumann, Philipp; Kosaka, Hideo; Wrachtrup, Jörg

    2016-08-01

    Long-distance quantum communication requires photons and quantum nodes that comprise qubits for interaction with light and good memory capabilities, as well as processing qubits for the storage and manipulation of photons. Owing to the unavoidable photon losses, robust quantum communication over lossy transmission channels requires quantum repeater networks. A necessary and highly demanding prerequisite for these networks is the existence of quantum memories with long coherence times to reliably store the incident photon states. Here we demonstrate the high-fidelity (˜98%) coherent transfer of a photon polarization state to a single solid-state nuclear spin that has a coherence time of over 10 s. The storage process is achieved by coherently transferring the polarization state of a photon to an entangled electron-nuclear spin state of a nitrogen-vacancy centre in diamond. The nuclear spin-based optical quantum memory demonstrated here paves the way towards an absorption-based quantum repeater network.

  8. Isospin symmetry breaking at high spin in the mirror nuclei Ar35 and Cl35

    NASA Astrophysics Data System (ADS)

    Vedova, F. Della; Lenzi, S. M.; Ionescu-Bujor, M.; Mărginean, N.; Axiotis, M.; Bazzacco, D.; Bizzeti-Sona, A. M.; Bizzeti, P. G.; Bracco, A.; Brandolini, F.; Bucurescu, D.; Farnea, E.; Iordachescu, A.; Lunardi, S.; Martínez, T.; Mason, P.; Menegazzo, R.; Million, B.; Napoli, D. R.; Nespolo, M.; Pavan, P.; Alvarez, C. Rossi; Ur, C. A.; Venturelli, R.; Zuker, A. P.

    2007-03-01

    High-spin states in Ar35 and Cl35 have been populated in the Mg24(O16, αn) and Mg24(O16, αp) reactions, respectively, at a beam energy of 70 MeV. The comparison between the level schemes of these mirror nuclei shows a striking asymmetry in the population yield of high-spin analog states of positive parity, which indicates different intensities of E1 transitions connecting positive- and negative-parity structures in both nuclei. Large energy differences are observed between analog states of negative parity with configurations of dominant pure single-particle character. This results from the comparison with large-scale shell-model calculations in the s1/2d3/2f7/2p3/2 valence space. It is shown that important contributions to the energy differences arise from the multipole Coulomb and the relativistic electromagnetic spin-orbit interactions.

  9. Observation of high-spin oblate band structures in {sup 141}Pm

    SciTech Connect

    Gu, L.; Zhu, S. J.; Wang, J. G.; Yeoh, E. Y.; Xiao, Z. G.; Zhang, M.; Liu, Y.; Ding, H. B.; Xu, Q.; Zhang, S. Q.; Meng, J.; Zhu, L. H.; Wu, X. G.; He, C. Y.; Li, G. S.; Wang, L. L.; Zheng, Y.; Zhang, B.

    2011-06-15

    The high-spin states of {sup 141}Pm have been investigated through the reaction {sup 126}Te({sup 19}F,4n) at a beam energy of 90 MeV. A previous level scheme has been updated with spins up to 49/2({h_bar}/2{pi}). Six collective bands at high spins are newly observed. Based on the systematic comparison, one band is proposed as a decoupled band; two bands with strong {Delta}I=1 M1 transitions inside the bands are suggested as the oblate bands with {gamma} {approx}-60 deg.; three other bands with large signature splitting have been proposed with the oblate-triaxial deformation with {gamma}{approx} -90 deg. The triaxial n-particle-n-hole particle rotor model calculations for one of the oblate bands in {sup 141}Pm are in good agreement with the experimental data. The other characteristics for these bands have been discussed.

  10. Dawn of High Energy Spin Physics — In Memory of Michel Borghini

    NASA Astrophysics Data System (ADS)

    Masaike, Akira

    2016-02-01

    High energy spin physics with the polarized proton target in 1960s is shown. The dynamic polarization in which the electronic polarization is transferred to protons in paramagnetic material by means of magnetic coupling was proposed at the beginning of 1960s. The first N-N experiment using a polarized proton target was performed with the crystal of La2Mg3 (NO3)1224H2O at CEN-Saclay and Berkeley in 1962, followed by π-p experiments in several laboratories. Protons in organic materials were found to be polarized up to 80% in 3He cryostats in 1969. It was helpful for large background experiments. High proton polarization was interpreted in the spin temperature theory. Spin frozen targets were constructed in early 1970s and used for experiments which require wide access angle. Michel Borghini was a main player for almost all the above works.

  11. Cobalt(II) β-ketoaminato complexes as novel inhibitors of neuroinflammation.

    PubMed

    Madeira, Jocelyn M; Beloukhina, Natalia; Boudreau, Kalun; Boettcher, Tyson A; Gurley, Lydia; Walker, Douglas G; McNeil, W Stephen; Klegeris, Andis

    2012-02-15

    Neuroinflammation contributes to the pathogenesis of neurological disorders including stroke, head trauma, multiple sclerosis, amyotrophic lateral sclerosis as well as age-associated neurodegenerative disorders including Alzheimer's and Parkinson's diseases. Therefore, anti-inflammatory drugs could be used to slow the progression of these diseases. We studied the anti-neuroinflammatory activity of four novel square planar cobalt(II) compounds bearing tetradentate β-ketoaminato ligands with variation in the number of CF(3) ligand substituents, as well as their corresponding unmetallated organic ligands. Cobalt (Co) complexes were consistently more active than their corresponding ligands. One of the complexes, L(3)Co at concentrations (1-10 μM) that were not toxic to cells, significantly reduced cytotoxic secretions by human monocytic THP-1 cells, astrocytoma U-373 MG cells, and primary human microglia. This anti-neurotoxic action of L(3)Co was reduced by SP600125 and PD98059, selective inhibitors of c-Jun NH2-terminal kinase (JNK) and extracellular signal regulated kinase (ERK) kinase (MEK)1/2 respectively. L(3)Co had no effect on secretion of monocyte chemotactic protein-1 (MCP-1) by THP-1 cells, but it inhibited the NADPH oxidase-dependent respiratory burst activity of differentiated human HL-60 cells. L(3)Co upregulated heme oxygenase-1 (HOX-1) expression by THP-1 cells, which may be one of the molecular mechanisms responsible for its anti-inflammatory properties. Two of the Co compounds tested showed activity only at high concentrations (50 μM), but L(2)Co was highly toxic to all cell types used. Select Co complexes, such as L(3)Co, may exhibit pharmacological properties beneficial in human diseases involving neuroinflammatory processes. Further studies of the in vivo efficacy, safety and pharmacokinetics of L(3)Co are warranted.

  12. Non-collective high-spin states in /sup 148/Dy

    SciTech Connect

    Dines, E.L.

    1985-04-01

    General physical concepts regarding nuclear high-spin states are given. The high-spin states in /sup 148/Dy(Z = 66, N = 82) were produced via the reaction /sup 112/Cd(Pb-backed)(/sup 40/Ar,4n) at E/sub lab/ = 175, at the 88-inch Cyclotron at Lawrence Berkeley Laboratory. Methods for placing gates on various transitions above and below the 480 nsec isomer at 10/sup +/(known from previous work), as well as for calculating transition intensities and their associated errors, are given. Calculations of angular correlations for multiple ..gamma..-ray cascades, assuming non-zero-width distributions in m-states for some given spin state, were done and compared to experimental values. Analysis of RF - Ge and Ge - Ge TAC spectra for transitions above the 480 nsec isomer implied lifetimes of less than or equal to 5 nsec (except for the 327.2 keV transition). Using such analysis, some 19 new ..gamma..-ray transitions were discovered above the isomer, thereby extending the /sup 148/Dy level scheme up to spin I = 31 h-bar. Assignments of spins and parities for the new levels are made based on information obtained from angular correlations and the lifetime limits. Previous work on the 11 transitions below the 480 nsec isomer is confirmed.

  13. Effects of Spin on High-energy Radiation from Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    O' Riordan, Michael; Pe'er, Asaf; McKinney, Jonathan C.

    2016-11-01

    Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points toward the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandford-Znajek (BZ) mechanism. We find that the X-ray and γ-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decreasing horizon radius. While the X-ray emission is dominated by the near horizon region, the near-infrared (NIR) radiation originates at larger radii. Therefore, the ratio of X-ray to NIR power is an observational signature of black hole spin.

  14. Electron spectral function and algebraic spin liquid for the normal state of underdoped high T(c) superconductors.

    PubMed

    Rantner, W; Wen, X G

    2001-04-23

    We propose to describe the spin fluctuations in the normal state (spin-pseudogap phase) of underdoped high T(c) cuprates as a manifestation of an algebraic spin liquid. Within the slave boson implementation of spin-charge separation, the normal state is described by massless Dirac fermions, charged bosons, and a gauge field. The gauge interaction, as an exact marginal perturbation, drives the mean-field free-spinon fixed point to a new spin-quantum fixed point-the algebraic spin liquid. Luttinger-liquid-like line shapes for the electron spectral function are obtained in the normal state, and we show how a coherent quasiparticle peak appears as spin and charge recombine.

  15. Universality, maximum radiation, and absorption in high-energy collisions of black holes with spin.

    PubMed

    Sperhake, Ulrich; Berti, Emanuele; Cardoso, Vitor; Pretorius, Frans

    2013-07-26

    We explore the impact of black hole spins on the dynamics of high-energy black hole collisions. We report results from numerical simulations with γ factors up to 2.49 and dimensionless spin parameter χ=+0.85, +0.6, 0, -0.6, -0.85. We find that the scattering threshold becomes independent of spin at large center-of-mass energies, confirming previous conjectures that structure does not matter in ultrarelativistic collisions. It has further been argued that in this limit all of the kinetic energy of the system may be radiated by fine tuning the impact parameter to threshold. On the contrary, we find that only about 60% of the kinetic energy is radiated for γ=2.49. By monitoring apparent horizons before and after scattering events we show that the "missing energy" is absorbed by the individual black holes in the encounter, and moreover the individual black-hole spins change significantly. We support this conclusion with perturbative calculations. An extrapolation of our results to the limit γ→∞ suggests that about half of the center-of-mass energy of the system can be emitted in gravitational radiation, while the rest must be converted into rest-mass and spin energy.

  16. Possible enhancements of AFM spin-fluctuations in high-TC cuprates

    NASA Astrophysics Data System (ADS)

    Jarlborg, Thomas

    2009-03-01

    Ab-initio band calculations for high-TC cuprates, together with modelling based of a free electron like band, show a strong interaction between anti-ferromagnetic (AFM) spin waves and periodic lattice distortions as for phonons, even though this type of spin-phonon coupling (SPC) is underestimated in calculations using the local density approximation. The SPC has a direct influence on the properties of the HTC cuprates and it can explain many observations. The strongest effects are seen for modulated waves in the CuO bond direction, and a band gap is formed near the X,Y points, but unusal band dispersion (like ``waterfalls'') might also be induced below the Fermi energy (EF) in the diagonal direction. The band results are used to propose different ways of increasing AFM spin-fluctuations locally, and to have a higher density-of-states (DOS) at EF. Static potential modulations, via periodic distribution of dopants or lattice distortions, can be tuned to increase the DOS. This opens for possibilities to enhance coupling for spin fluctuations (λsf) and superconductivity. The exchange enhancement is in general increased near a surface, which suggests a tendency towards static spin configurations. The sensivity of the band results to corrections of the local density potential are discussed.

  17. Giant spin-driven ferroelectric polarization in TbMnO3 under high pressure.

    PubMed

    Aoyama, T; Yamauchi, K; Iyama, A; Picozzi, S; Shimizu, K; Kimura, T

    2014-09-12

    The recent research on multiferroics has provided solid evidence that the breaking of inversion symmetry by spin order can induce ferroelectric polarization P. This type of multiferroics, called spin-driven ferroelectrics, often show a gigantic change in P on application of a magnetic field B. However, their polarization (<~0.1 μC cm(-2)) is much smaller than that in conventional ferroelectrics (typically several to several tens of μC cm(-2)). Here we show that the application of external pressure to a representative spin-driven ferroelectric, TbMnO3, causes a flop of P and leads to the highest P (≈ 1.0 μC cm(-2)) among spin-driven ferroelectrics ever reported. We explain this behaviour in terms of a pressure-induced magnetoelectric phase transition, based on the results of density functional simulations. In the high-pressure phase, the application of B further enhances P over 1.8 μC cm(-2). This value is nearly an order of magnitude larger than those ever reported in spin-driven ferroelectrics.

  18. Novel spin-on organic hardmask with high plasma etch resistance

    NASA Astrophysics Data System (ADS)

    Oh, Chang-Il; Lee, Jin-Kuk; Kim, Min-Soo; Yoon, Kyong-Ho; Cheon, Hwan-Sung; Tokareva, Nataliya; Song, Jee-Yun; Kim, Jong-Seob; Chang, Tu-Won

    2008-03-01

    In recent years for memory devices under 70nm using ArF lithography, spin-on organic hardmask has become an attractive alternative process to amorphous carbon layer hardmark (ACL) in mass production due to ACL hardmask's limited capacity, high cost-of-ownership, and low process efficiency in spite of its excellent etch performance. However, insufficient plasma etch resistance of spin-on hardmask makes the etch process an issue resulting in inadequate vertical profiles, large CD bias, and narrow etch process window compared to ACL hardmask. In order to be able to apply these spin on hardmasks to varies layers including critical layers, the aforementioned problems need to be resolved and verified using several evaluation methods including etch pattern evaluation. In this paper, we report the synthesis of novel organic spin-on hardmasks (C-SOH) that incorporate various fused aromatic moieties into polymer chain and the evaluation of etch performance using dry etch tools. Organic spin-on hardmasks with 79-90 wt% carbon contents were synthesized in-house. Oxygen and fluorine based plasma etch processes were used to evaluate the etch resistance of the C-SOH. The results show our 3rd generation C-SOH has etch profiles comparable to that of ACL in a 1:1 dense pattern.

  19. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP CIRCUM-PAN-PACIFIC RIKEN SYMPOSIUM ON HIGH ENERGY SPIN PHYSICS, VOLUME 25

    SciTech Connect

    KUMANO,S.; SHIBATA,T.A.; YAZAKI,K.

    2000-06-28

    The Circum-Pan-Pacific Riken Symposium on High Energy Spin Physics was held at Oukouchi Memorial Hall in Riken from November 3 through 6, 1999. It was held as a joint meeting of the 2nd Circum-Pan-Pacific Symposium on High Energy Spin Physics and the 3rd of the series of Riken Symposia related to the RHIC-SPIN. The 1st Circum-Pan-Pacific Symposium on High Energy Spin Physics was held at Kobe in 1996 and the RHIC-SPIN Riken Symposia had been held every two years since 1995. As Prof. Ozaki mentioned in his talk at the beginning of this meeting, the RHIC was ready for the first beam, physics experiments scheduled in 2000, and the RHIC-SPIN would start in 2001. It was therefore considered to be very timely for the researchers in the field of high energy spin physics to get together, clarifying the present status of the field and discussing interesting and important topics as well as experimental subjects to be pursued. It is especially important for the success of the RHIC-SPIN project that the researchers in the neighboring countries surrounding the Pacific are actively involved in it. This is why the above two series were joined in this. symposium. The subjects discussed in the symposium include: Hard processes probing spin-structure functions, polarization mechanisms in high energy reactions, lattice studies of polarized structure functions, theoretical models for the nucleon and its spin structure, RHIC and RHIC-SPIN projects, results and future projects of existing experimental facilities. Totally 73 scientists participated in the symposium, 27 from abroad and 46 from Japan. it consisted of 13 main sessions, with 33 invited and contributed talks, and 4 discussion sessions covering recent experimental and theoretical developments and important topics in high energy spin physics and closely related fields.

  20. High-Spin States in Transuranium Nuclei 242,244Pu

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Kang, Xu-Zhong; Shen, Shui-Fa; Yan, Yu-Peng; He, Chuang-Ye; Yan, Shi-Wei

    2012-05-01

    We investigate the structure of yrast bands in the transuranium nuclei 242Pu and 244Pu in the framework of the projected shell model, which is a fully quantum mechanical and microscopic approach. It is found that an appropriate modification of the standard Nilsson spin-orbital parameters in the N = 6 proton shell is necessary to correctly describe the high-spin backbending phenomenon in nucleus 244Pu. In order to test whether this modification is correct, the same modified parameters are used to calculate the yrast band of its neighboring isotope 242Pu. It is found that without this modification, a backbending will occur at spin I = 20, which is not supported by the experimental data.

  1. High spin polarization in CoFeMnGe equiatomic quaternary Heusler alloy

    SciTech Connect

    Bainsla, Lakhan; Suresh, K. G.; Nigam, A. K.; Manivel Raja, M.; Varaprasad, B. S. D. Ch. S.; Takahashi, Y. K.; Hono, K.

    2014-11-28

    We report the structure, magnetic property, and spin polarization of CoFeMnGe equiatomic quaternary Heusler alloy. The alloy was found to crystallize in the cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO{sub 3} disorder. Thermal analysis result indicated the Curie temperature is about 750 K without any other phase transformation up to melting temperature. The magnetization value was close to that predicted by the Slater-Pauling curve. Current spin polarization of P = 0.70 ± 0.01 was deduced using point contact andreev reflection measurements. The temperature dependence of electrical resistivity has been fitted in the temperature range of 5–300 K in order to check for the half metallic behavior. Considering the high spin polarization and Curie temperature, this material appears to be promising for spintronic applications.

  2. Spin crossover in Fe2SiO4 liquid at high pressure

    NASA Astrophysics Data System (ADS)

    Ramo, David Muñoz; Stixrude, Lars

    2014-07-01

    We combine spin-polarized density functional theory with first principle molecular dynamics (FPMD) to study the spin crossover in liquid Fe2SiO4, up to 300 GPa and 6000 K. In contrast to the much sharper transition seen in crystals, we find that the high- to low-spin transition occurs over a very broad pressure interval (>200 GPa) due to structural disorder in the liquid. We find excellent agreement with the experimental Hugoniot. We combine our results with previous FPMD calculations to derive the partial molar volumes of the oxide components MgO, FeO, and SiO2. We find that eutectic melts in the MgO-FeO-SiO2 system are denser than coexisting solids in the bottom 600 km of Earth's mantle.

  3. High-spin states and shell structure of the odd-odd nucleus {sup 90}Nb

    SciTech Connect

    Cui, X.Z.; Zhang, Z.L.; Meng, R.; Yang, C.X.; Zhu, L.H.; Wu, X.G.; Wang, Z.M.; He, C.Y.; Li, G.S.; Wen, S.X.; Ma, R.G.; Liu, Y.; Luo, P.; Zheng, Y.; Ndontchueng, M.M.; Huo, J.D.

    2005-10-01

    The high-spin states of the odd-odd nucleus {sup 90}Nb have been investigated with in-beam {gamma}-spectroscopic techniques via the {sup 76}Ge({sup 19}F,5n){sup 90}Nb reaction at a beam energy of 80 MeV. {gamma}-{gamma} coincidences were measured using a {gamma}-ray detector array. Twenty new {gamma} rays have been assigned to {sup 90}Nb and the level scheme has been extended up to an excitation energy of 8.095 MeV at spin 18({Dirac_h}/2{pi}). The level structure of {sup 90}Nb at high spin states has been well reproduced using semiempirical shell-model calculations in the model space {pi}(1p{sub 1/2},0f{sub 5/2},0g{sub 9/2}){nu}(0g{sub 9/2}). The results show that the excitation of protons plays an important role in generating the high-spin states of {sup 90}Nb.

  4. Charge and spin correlations in high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Hayden, Stephen

    2013-03-01

    The cuprate high temperatures superconductors are characterised by numerous competing, and in some cases, co-existing broken symmetries. A important question is to what extent such additional ordered states exist for compositions with high superconducting transition temperatures. I will discuss high-energy X-ray diffraction measurements which show that a charge density wave state (CDW) develops at zero field in the normal state of superconducting YBa2Cu3O6.67 (Tc = 67 K). This material has a hole doping of 0.12 per copper and a well-ordered oxygen chain superstructure. Below Tc, the application of a magnetic field suppresses superconductivity and enhances the CDW. We find that the CDW and superconductivity are competing orders with similar energy scales, and the high-Tc superconductivity forms from a pre-existing CDW environment. Our results provide a mechanism for the formation of small Fermi surface pockets which can explain the negative Hall and Seebeck effects and the Tc plateau in this material. Work performed in collaboration with J. Chang, E. Blackburn, A. T. Holmes, N. B. Christensen, J. Larsen, J. Mesot, Ruixing Liang, D. A. Bonn, W. N. Hardy, A. Watenphul, M. v. Zimmermann and E. M. Forgan.

  5. NMR spectroscopy of hyperpolarized ^129Xe at high fields: Maintaining spin polarization after optical pumping.

    NASA Astrophysics Data System (ADS)

    Patton, Brian; Kuzma, Nicholas N.; Lisitza, Natalia V.; Happer, William

    2003-05-01

    Spin-polarized ^129Xe has become an invaluable tool in nuclear magnetic resonance research, with applications ranging from medical imaging to high-resolution spectroscopy. High-field NMR studies using hyperpolarized xenon as a spectroscopic probe benefit from the high signal-to-noise ratios and large chemical shifts typical of optically-pumped noble gases. The experimental sensitivity is ultimately determined by the absolute polarization of the xenon in the sample, which can be substantially decreased during purification and transfer. NMR of xenon at high fields (9.4 Tesla) will be discussed, and potential mechanisms of spin relaxation during the distillation, storage(N. N. Kuzma, B. Patton, K. Raman, and W. Happer, Phys. Rev. Lett. 88), 147602 (2002)., and delivery of hyperpolarized xenon will be analyzed.

  6. PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

    SciTech Connect

    Staszczak, A.; Wong, Cheuk-Yin

    2015-01-01

    Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

  7. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    NASA Astrophysics Data System (ADS)

    Thomas, Luc; Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang

    2014-05-01

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 kBT/μA, energy barriers higher than 100 kBT at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  8. Measuring the Spin Period of a High-Velocity Pulsar

    NASA Astrophysics Data System (ADS)

    Tomsick, John

    2012-10-01

    X-ray observations of IGR J11014-6103 show that it has a complex morphology with a point source and two components of extended emission. Its properties indicate that it is very likely to be a pulsar wind nebula (PWN). Chandra and radio observations strongly suggest that the compact object is moving away from SNR MSH 11-61A. Based on the evolution of this supernova remnant, an association would indicate that IGR J11014-6103 has a transverse velocity of 2,400 to 2,900 km/s. The possibility of such a high kick velocity makes the proposed timing study important for proving that the compact object is a pulsar, determining its period (P), and measuring dP/dt to determine if the characteristic age is consistent with the pulsar originating in MSH 11-61A.

  9. Structural and magnetic properties of cobalt(II) complexes with pyridinecarboxamide ligands

    NASA Astrophysics Data System (ADS)

    Dojer, Brina; Pevec, Andrej; Belaj, Ferdinand; Jagličić, Zvonko; Kristl, Matjaž; Drofenik, Miha

    2014-11-01

    The synthesis and characterization of two new cobalt(II) coordination compounds with nicotinamide (nia) and isonicotinamide (isn) are reported. The products were characterized magnetically, structurally by single-crystal X-ray diffraction analysis and spectrally by FT-IR spectroscopy. Using the reaction of cobalt(II) acetate tetrahydrate and nicotinamide in methanol we obtained light-red crystals of the mononuclear complex [Co(nia)2(H2O)4](CH3COO)2·2H2O (1). The synthesis in a system cobalt(II) acetate dihydrathe, isonicotinamide and dimethylformamide-methanol mixture gave a new dinuclear coordination compound with the formula [Co2(CH3COO)4(isn)4]·2C3H7NO (2). In both compounds a trans arrangement of pyridinecarboxamide ligands was found. Intermolecular hydrogen bonds in the crystal structures of both complexes are discussed. The magnetic properties were studied between 2 K and 300 K giving the result μeff = 4.6 BM for 1 and μeff = 4.7 BM for 2 in the paramagnetic region.

  10. Observation of high-spin bands with large moments of inertia in 124Xe

    NASA Astrophysics Data System (ADS)

    Nag, Somnath; Singh, A. K.; Hagemann, G. B.; Sletten, G.; Herskind, B.; Døssing, T.; Ragnarsson, I.; Hübel, H.; Bürger, A.; Chmel, S.; Wilson, A. N.; Rogers, J.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Kondev, F. G.; Lauritsen, T.; Zhu, S.; Korichi, A.; Stefanova, E. A.; Fallon, P.; Nyakó, B. M.; Timár, J.; Juhász, K.

    2016-09-01

    High-spin states in 124Xe have been populated using the 80Se(48Ca,4 n ) reaction at a beam energy of 207 MeV and high-multiplicity, γ -ray coincidence events were measured using the Gammasphere spectrometer. Six high-spin bands with large moments of inertia, similar to those observed in neighboring nuclei, have been observed. The experimental results are compared with calculations within the framework of the cranked Nilsson-Strutinsky model. It is suggested that the configurations of the bands involve excitations of protons across the Z =50 shell gap coupled to neutrons within the N =50 -82 shell or excited across the N =82 shell closure.

  11. Observation of high-spin bands with large moments of inertia in Xe124

    DOE PAGES

    Nag, Somnath; Singh, A. K.; Hagemann, G. B.; ...

    2016-09-07

    In this paper, high-spin states in 124Xe have been populated using the 80Se(48Ca, 4n) reaction at a beam energy of 207 MeV and high-multiplicity, γ-ray coincidence events were measured using the Gammasphere spectrometer. Six high-spin rotational bands with moments of inertia similar to those observed in neighboring nuclei have been observed. The experimental results are compared with calculations within the framework of the Cranked Nilsson-Strutinsky model. Finally, it is suggested that the configurations of the bands involve excitations of protons across the Z = 50 shell gap coupled to neutrons within the N = 50 - 82 shell or excitedmore » across the N = 82 shell closure.« less

  12. High spin spectroscopy for A approx 160 nuclei

    SciTech Connect

    Yu, C.-H. Tennessee Univ., Knoxville, TN . Dept. of Physics and Astronomy); Gascon, J.; Garrett, J.D.; Hagemann, G.B. )

    1989-01-01

    Experimental routhians, alignments, band crossing frequencies, and the B(M1)/B(E2) ratios of the N = 90 isotopes and several light Lu (N = 90--96) isotopes are summarized and discussed in terms of shape changes. These systematic analyses show a neutron and proton number dependent deformations (both quadruple and {gamma} deformations) for these light rare earth nuclei. The stability of the nuclear deformation with respect to {beta} and {gamma} is also found to be particle number dependent. Such particle number dependent shapes can be attributed to the different locations of the proton and neutron Fermi levels in the Nilsson diagrams. Configurations dependent shapes are discussed specially concerned the deformation difference between the proton h{sub 9/2}1/2{sup -}(541) and the high-K h{sub 11/2} configurations. The observed large neutron band crossing frequencies in the h{sub 9/2}1/2{sup -}(541) configuration support the predicted large deformation of this configuration but can be reproduced by the cranked shell model calculation according to the predicted deformations. Lifetime measurement for {sup 157}Ho, one of the nuclei that show a large {h bar}{omega}{sup c} in the 1/2{sup -}(541) band, indicates that deformation difference can only account for 20% of such shift in {h bar}{omega}{sub c}. 55 refs., 12 figs.

  13. Revisiting spin-lattice relaxation time measurements for dilute spins in high-resolution solid-state NMR spectroscopy.

    PubMed

    Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua

    2016-07-01

    Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as (13)C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. (13)C) and abundant I (e.g. (1)H) spins affects the measured T1S values in solid-state NMR in the absence of (1)H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance l-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions.

  14. Octanuclear zinc(II) and cobalt(II) clusters produced by cooperative tetrameric assembling of oxime chelate ligands.

    PubMed

    Akine, Shigehisa; Dong, Wenkui; Nabeshima, Tatsuya

    2006-06-12

    We have synthesized an octanuclear zinc(II) cluster [L4Zn8(H2O)3] by the complexation of 3-hydroxysalamo (H4L) with zinc(II) acetate. The complex crystallizes in the triclinic system, space group P, with unit cell parameters a = 18.233(10) A, b = 20.518(11) A, c = 21.366(11) A, alpha = 98.7557(2) degrees, beta = 99.191(11) degrees, gamma = 108.309(10) degrees, and Z = 4. The crystallographic analysis revealed the S4 symmetrical assembling of four ligands and that the tetrameric complex has three water molecules in an unsymmetrical fashion. Spectroscopic analysis of the complex strongly suggests that the octanuclear cluster also exists in solution and maintains a conformation similar to that in the crystal structure, although exchange of the coordinating water molecules presumably takes place. In addition, the formation process of the octanuclear complex is highly cooperative. A high coordinating ability of the [(salamo)Zn] unit as well as the catecholato2- moieties probably stabilizes the octanuclear assembly and makes the complexation process cooperative. The corresponding octanuclear cobalt(II) cluster [L4Co8(EtOH)3] was prepared in a similar manner. Complex [L4Co8(H2O)2X] (X = H2O or EtOH) was obtained by the recrystallization from chloroform/hexane. The complex crystallizes in the triclinic system, space group P, with unit cell parameters a = 15.2359(10) A, b = 16.9625(12) A, c = 18.9325(13) A, alpha = 101.9710(10) degrees, beta = 105.5410(10) degrees, gamma = 97.1290(10) degrees, and Z = 2. Temperature dependence of magnetic susceptibility showed a continuous decrease in the chi(M)T value with decreasing temperature, suggesting antiferromagnetic interaction among cobalt(II) ions. The magnetic susceptibility above 40 K obeys the Curie-Weiss law with a Weiss constant theta of -39 K and a Curie constant C of 19.7 cm(3) K mol(-1).

  15. Sol-gel synthesized adsorbents for mercury(II), chromium(III) and cobalt(II) separations

    NASA Astrophysics Data System (ADS)

    Nam, Kwan-Hyun

    Novel organo-ceramic adsorbents are synthesized and characterized for mercury(II), chromium(III) and cobalt(II) separations from aqueous streams. Mercury(II) adsorption on thiol functional adsorbents (SOL-AD-IV) is studied for two systems: (1) coal-fired utility plant scrubber water, and (2) acidic nuclear wastes. To exemplify the removal of mercury from these systems, simulants are prepared and used. Results show that the mercury adsorption capacity is higher than reported in the literature. In addition, the adsorbent exhibits high adsorption capacity even at 4 M HNO3. In column operation, flow rates as high as 1100 BV/h could be employed with effluent concentrations reaching below 0.06 mug/L. This adsorbent is found to exhibit superior mercury adsorption characteristics with a demonstrated long life cycle. Chromium(III) and cobalt(II) adsorption is evaluated using phosphonic acid (SOL-PHONIC) and phosphinic acid (SOL-PHINIC) functional adsorbents synthesized via sol-gel processing by co-condensation of clusters of functional precursor (FPS) and cross-linking (CA) silanes. Nuclear magnetic resonance (NMR) spectroscopy is used to examine the evolution of oligomeric species with hydrolysis and condensation reaction times. The effects of both the FPS and CA oligomeric species on the physicochemical properties of the resulting adsorbent materials are evaluated and explained in terms of structural and adsorption capacity characteristics. The adsorbents are further characterized by solid-state NMR spectroscopy to elucidate the incorporation of the FPS and the nature of the functional groups in the adsorbent matrix. SOL-PHONIC is employed for the removal of chromium, and both SOL-PHONIC and SOL-PHINIC are employed for the removal of cobalt. Results show that chromium and cobalt adsorptions are solution pH dependent. Cobalt adsorption tests evaluated using the two adsorbents show that SOL-PHONIC exhibits a higher selectivity towards cobalt over nickel. The adsorption

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  17. High-performance spinning device for DVD-based micromechanical signal transduction

    NASA Astrophysics Data System (ADS)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo G.; Wang, Wei-Min; Ko, Hsien-Chen; Hwang, Ing-Shouh; Boisen, Anja; Huang, Kuang-Yuh

    2013-04-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning mechanism, this device can simultaneously measure surface topography, mechanical deflections and resonance frequencies of several microfabricated beams at a high speed. In biochemical sensing applications, the OPU can measure bending changes of functionalized microcantilevers, providing a statistically robust and label-free bio-detection analysis of multiple compounds. The signal-to-noise ratio (S/N) is demonstrated from statistical measurements as 1.2 with arginine detection at 750 nM concentration. Practically, the OPU can measure up to 480 individual cantilever sensors per second with nanometer resolution. The opto-mechanical optimization of the device design and settings for biochemical detection are described.

  18. Stanene cyanide: a novel candidate of Quantum Spin Hall insulator at high temperature

    PubMed Central

    Ji, Wei-xiao; Zhang, Chang-wen; Ding, Meng; Li, Ping; Li, Feng; Ren, Miao-juan; Wang, Pei-ji; Hu, Shu-jun; Yan, Shi-shen

    2015-01-01

    The search for quantum spin Hall (QSH) insulators with high stability, large and tunable gap and topological robustness, is critical for their realistic application at high temperature. Using first-principle calculations, we predict the cyanogen saturated stanene SnCN as novel topological insulators material, with a bulk gap as large as 203 meV, which can be engineered by applying biaxial strain and electric field. The band topology is identified by Z2 topological invariant together with helical edge states, and the mechanism is s-pxy band inversion at G point induced by spin-orbit coupling (SOC). Remarkably, these systems have robust topology against chemical impurities, based on the calculations on halogen and cyano group co-decorated stanene SnXxX′1−x (X,X′  =  F, Cl, Br, I and CN), which makes it an appropriate and flexible candidate material for spintronic devices. PMID:26688269

  19. High aspect ratio etching using a fullerene derivative spin-on-carbon hardmask

    NASA Astrophysics Data System (ADS)

    Frommhold, A.; Manyam, J.; Palmer, R. E.; Robinson, A. P. G.

    2012-03-01

    As lithographic resolution has increased to meet the demand for smaller devices it has been necessary to use extremely thin photoresist films to mitigate aspect ratio related resist feature collapse during development. Even with high etchdurability photoresists, usable photoresist thickness limits etch depth, and it is becoming increasingly difficult to transfer the pattern directly from the photoresist to the substrate. As feature sizes have diminished the use of multilayer etch stacks has been increasingly investigated to further increase aspect ratio. Typically, a thick layer of amorphous carbon is deposited by chemical vapor deposition, and then coated with thin silicon and resist layers. To improve manufacturability it would be beneficial to use spin-on-carbon in the bottom layer. Here we introduce a fullerene based spin-on carbon with high etch-durability. Sub 50 nm features with aspect ratios in excess of 15:1 have been produced in silicon using ICP etching.

  20. High-spin states in {sup 205}Rn: A new shears band structure?

    SciTech Connect

    Novak, J.R.; Beausang, C.W.; Casten, R.F.; Cata Danil, G.; Cooper, J.R.; Juutinen, S.; Kruecken, R.; Liu, B.; Socci, T.; Thomas, J.T.; Zamfir, N.V.; Zhang, J.; Amzal, N.; Greenlees, P.T.; Cata Danil, G.; Zamfir, N.V.; Cocks, J.F.; Greenlees, P.T.; Helariutta, K.; Jones, P.; Julin, R.; Kankaanpaeae, H.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Savelius, A.; Hannachi, F.; Zamfir, N.V.; Zhang, J.; Frauendorf, S.

    1999-06-01

    The high-spin structure of {sup 205}Rn has been investigated for the first time following the {sup 170}Er({sup 40}Ar,5n) and {sup 197}Au({sup 14}N,6n) reactions at beam energies of 183 MeV and 90{endash}110 MeV, respectively, using the Jurosphere and YRAST Ball arrays. Two new cascades have been identified which dominate the high-spin decay. One of these, consisting of ten stretched M1 transitions with unobserved E2 crossover transitions, is interpreted as a shears structure based on the {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}i{sub 13/2}{sup 2} (or {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}h{sub 9/2}i{sub 13/2}) configuration. {copyright} {ital 1999} {ital The American Physical Society}

  1. Equation-of-motion coupled cluster method for high spin double electron attachment calculations

    SciTech Connect

    Musiał, Monika Lupa, Łukasz; Kucharski, Stanisław A.

    2014-03-21

    The new formulation of the equation-of-motion (EOM) coupled cluster (CC) approach applicable to the calculations of the double electron attachment (DEA) states for the high spin components is proposed. The new EOM equations are derived for the high spin triplet and quintet states. In both cases the new equations are easier to solve but the substantial simplification is observed in the case of quintets. Out of 21 diagrammatic terms contributing to the standard DEA-EOM-CCSDT equations for the R{sub 2} and R{sub 3} amplitudes only four terms survive contributing to the R{sub 3} part. The implemented method has been applied to the calculations of the excited states (singlets, triplets, and quintets) energies of the carbon and silicon atoms and potential energy curves for selected states of the Na{sub 2} (triplets) and B{sub 2} (quintets) molecules.

  2. Large Magnetoresistance at High Bias Voltage in Double-layer Organic Spin Valves

    NASA Astrophysics Data System (ADS)

    Subedi, R. C.; Liang, S. H.; Geng, R.; Zhang, Q. T.; Lou, L.; Wang, J.; Han, X. F.; Nguyen, T. D.

    We report studies of magnetoresistance (MR) in double-layer organic spin valves (DOSV) using tris (8-hydroxyquinolinato) aluminum (Alq3) spacers. The device exhibits three distinct resistance levels depending on the relative magnetizations of the ferromagnetic electrodes. We observed a much weaker bias voltage dependence of MR in the device compared to that in the conventional organic spin valve (OSV). The MR magnitude reduces by the factor of two at 0.7 V bias voltage in the DOSV compared to 0.02 V in the conventional OSV. Remarkably, the MR magnitude reaches 0.3% at 6 V bias in the DOSVs, the largest MR response ever reported in OSVs at this bias. Our finding may have a significant impact on achieving high efficient bipolar OSVs strictly performed at high voltages. University of Georgia start-up fund, Ministry of Education, Singapore, National Natural Science Foundation of China.

  3. High-spin chloro mononuclear MnIII complexes: a multifrequency high-field EPR study.

    PubMed

    Mantel, Claire; Chen, Hongyu; Crabtree, Robert H; Brudvig, Gary W; Pécaut, Jacques; Collomb, Marie-Noëlle; Duboc, Carole

    2005-03-01

    The isolation, structural characterization, and electronic properties of two six-coordinated chloromanganese (III) complexes, [Mn(terpy)(Cl)3] (1) and [Mn(Phterpy)(Cl)3] (2), are reported (terpy = 2,2':6'2"-terpyridine, Phterpy = 4'-phenyl-2,2':6',2"-terpyridine). These complexes complement a series of mononuclear azide and fluoride Mn(lll) complexes synthesized with neutral N-tridentate ligands, [Mn(L)(X)3] (X = F- or N3 and L = terpy or bpea [N,N-bis(2-pyridylmethyl)-ethylamine)], previously described. Similar to these previous complexes, 1 and 2 exhibit a Jahn-Teller distortion of the octahedron, characteristic of a high-spin Mn(III) complex (S = 2). The analysis of the crystallographic data shows that, in both cases, the manganese ion lies in the center of a distorted octahedron characterized by an elongation along the tetragonal axis. Their electronic properties were investigated by multifrequency EPR (190-475 GHz) performed in the solid state at different temperatures (5-15 K). This study confirms our previous results and further shows that: i) the sign of D is correlated with the nature of the tetragonal distortion; ii) the magnitude of D is not sensitive to the nature of the anions in our series of rhombic complexes, contrary to the porphyrinic systems; iii) the [E/D] values (0.124 for 1 and 0.085 for 2) are smaller compared to those found for the [Mn(L)(X)3] complexes (in the range of 0.146 to 0.234); and iv) the E term increases when the ligand-field strength of the equatorial ligands decreases.

  4. Rhenium-phthalocyanine molecular nanojunction with high magnetic anisotropy and high spin filtering efficiency

    SciTech Connect

    Li, J.; Hu, J.; Wang, H.; Wu, R. Q.

    2015-07-20

    Using the density functional and non-equilibrium Green's function approaches, we studied the magnetic anisotropy and spin-filtering properties of various transition metal-Phthalocyanine molecular junctions across two Au electrodes. Our important finding is that the Au-RePc-Au junction has both large spin filtering efficiency (>80%) and large magnetic anisotropy energy, which makes it suitable for device applications. To provide insights for the further experimental work, we discussed the correlation between the transport property, magnetic anisotropy, and wave function features of the RePc molecule, and we also illustrated the possibility of controlling its magnetic state.

  5. Band structures extending to very high spin in {sup 126}Xe

    SciTech Connect

    Roenn Hansen, C.; Sletten, G.; Hagemann, G. B.; Herskind, B.; Jensen, D. R.; Bringel, P.; Engelhardt, C.; Huebel, H.; Neusser-Neffgen, A.; Singh, A. K.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Bednarczyk, P.; Byrski, T.; Curien, D.; Benzoni, G.; Bracco, A.; Camera, F.

    2007-09-15

    High-spin states in {sup 126}Xe have been populated in the {sup 82}Se({sup 48}Ca,4n){sup 126}Xe reaction in two experiments, one at the VIVITRON accelerator in Strasbourg using the Euroball detector array, and a subsequent one with ATLAS at Argonne using the Gammasphere Ge-detector array. Levels and assignments made previously for {sup 126}Xe up to I=20 have been confirmed and extended. Four regular bands extending to a spin of almost I=60, which are interpreted as two pairs of signature partners with opposite parity, are identified for the first time. The {alpha} = 0 partner of each pair is connected to the lower-lying levels, whereas the two {alpha} = 1 partners remain floating. A fractional Doppler shift analysis of transitions in the strongest populated ({pi},{alpha})=(-,0) band provides a value of 5.2{sub 0.5}{sup 0.4} b for the transition quadrupole moment, which can be related to a minimum in the potential-energy surface calculated by the ULTIMATE CRANKER cranked shell-model code at {epsilon}{approx_equal}0.35 and {gamma}{approx_equal}5 deg. The four lowest bands calculated for this minimum compare well with the two signature pairs experimentally observed over a wide spin range. A sharp upbend at ({Dirac_h}/2{pi}){omega}{approx}1170 keV is interpreted as a crossing with a band involving the j{sub 15/2} neutron orbital, for which pairing correlations are expected to be totally quenched. The four long bands extend to within {approx}5 spin units of a crossing with an yrast line defined by calculated hyperdeformed transitions and will serve as important stepping stones into the spin region beyond 60h for future experiments.

  6. Magnetic resonance spectroscopy editing techniques of coupled spin systems at high field

    NASA Astrophysics Data System (ADS)

    Snyder, Jeff

    , the effect of radiofrequency interference effects was studied at high field to investigate signal losses due to reduced excitation and refocusing in spectroscopic images. Possible differences between coupled and uncoupled spin systems were investigated in spectroscopic imaging at 4.7 T.

  7. High power ferromagnetic resonance and spin wave instability processes in Permalloy thin films

    NASA Astrophysics Data System (ADS)

    An, Sung Yong; Krivosik, Pavol; Kraemer, Michael A.; Olson, Heidi M.; Nazarov, Alexey V.; Patton, Carl E.

    2004-08-01

    The high power ferromagnetic resonance (FMR) response, as well as butterfly curves of the spin wave instability threshold microwave field amplitude hcrit versus in-plane static field H profiles, have been measured for Permalloy films with thicknesses of 104, 128, and 270nm at a nominal pumping frequency of 9.37GHz. The hcrit values range from about 1 to 7Oe. Both the resonance saturation response at the FMR field and the subsidiary absorption (SA) response for static fields below the FMR field are similar in appearance to those for bulk ferrites. Butterfly curves over the SA response region, while similar to those for ferrites, exhibit a film thickness dependent band edge cutoff effect not found in bulk ferrites. The SA butterfly curve data were analyzed on the basis of a spin wave instability theory adapted to thin films. The observed shift in the SA band edge cutoff with thickness agrees with calculations based on the thin film dispersion response and the assumption of first order instability processes with critical modes at one half the pumping frequency. The fitted SA spin wave linewidths give values consistent with metallic relaxation processes, but indicate critical modes with wave vectors that always make relatively small 0°-20° angles with the static field, very different from the critical modes for bulk ferrites. Three key conclusions from this work are (1) the nonlinear microwave FMR response in Permalloy films is a threshold effect related to well established spin wave instability processes, (2) the details of the SA response are controlled largely by the thin film spin wave dispersion, and (3) these nonlinear processes occur for very small precession angles.

  8. Satellite transitions acquired in real time by magic angle spinning (STARTMAS): ``Ultrafast'' high-resolution MAS NMR spectroscopy of spin I =3/2 nuclei

    NASA Astrophysics Data System (ADS)

    Thrippleton, Michael J.; Ball, Thomas J.; Wimperis, Stephen

    2008-01-01

    The satellite transitions acquired in real time by magic angle spinning (STARTMAS) NMR experiment combines a train of pulses with sample rotation at the magic angle to refocus the first- and second-order quadrupolar broadening of spin I =3/2 nuclei in a series of echoes, while allowing the isotropic chemical and quadrupolar shifts to evolve. The result is real-time isotropic NMR spectra at high spinning rates using conventional MAS equipment. In this paper we describe in detail how STARTMAS data can be acquired and processed with ease on commercial equipment. We also discuss the advantages and limitations of the approach and illustrate the discussion with numerical simulations and experimental data from four different powdered solids.

  9. NMR high-resolution magic angle spinning rotor design for quantification of metabolic concentrations

    NASA Astrophysics Data System (ADS)

    Holly, R.; Damyanovich, A.; Peemoeller, H.

    2006-05-01

    A new high-resolution magic angle spinning nuclear magnetic resonance technique is presented to obtain absolute metabolite concentrations of solutions. The magnetic resonance spectrum of the sample under investigation and an internal reference are acquired simultaneously, ensuring both spectra are obtained under the same experimental conditions. The robustness of the technique is demonstrated using a solution of creatine, and it is shown that the technique can obtain solution concentrations to within 7% or better.

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

    NASA Astrophysics Data System (ADS)

    Staszczak, A.; Wong, Cheuk-Yin

    2015-11-01

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

  11. Synthesis and spectroscopic characterization of high-spin mononuclear iron(II) p-semiquinonate complexes.

    PubMed

    Baum, Amanda E; Park, Heaweon; Lindeman, Sergey V; Fiedler, Adam T

    2014-12-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin Fe(II) center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  12. Proton-mediated electron configuration change in high-spin iron(II) porphyrinates.

    PubMed

    Hu, Chuanjiang; Noll, Bruce C; Schulz, Charles E; Scheidt, W Robert

    2005-11-02

    The synthesis, molecular structure, and electronic structure characterization of two five-coordinate high-spin imidazolate-ligated iron(II) porphyrinates are reported. Their electronic structure, as deduced from Mössbauer spectra obtained in strong magnetic fields, is distinctly different from that of the analogous imidazole-ligated species. The resulting electronic structure models are consistent with all observed differing features in the two classes.

  13. Delayed autoionization of recoil ions by the decay of high-spin isomeric states

    NASA Astrophysics Data System (ADS)

    Maidikov, V. Z.

    1985-12-01

    The time dependence of the ionization for isotopically different heavy ion fusion recoil ions has been observed. Delayed nuclear-induced autoionization of recoil ions caused by the decay of high-spin nuclear isomeric states by internal conversion was established. Internal conversion in isolated recoil atoms results in a drastic rearrangement in the atomic cloud with a loss of a great number of orbital electrons. Possibilities for the use of the observed phenomena in atomic and nuclear physics are discussed.

  14. Electron spin transition causing structure transformations of earth's interiors under high pressure

    NASA Astrophysics Data System (ADS)

    Yamanaka, T.; Kyono, A.; Kharlamova, S.; Alp, E.; Bi, W.; Mao, H.

    2012-12-01

    To elucidate the correlation between structure transitions and spin state is one of the crucial problems for understanding the geophysical properties of earth interiors under high pressure. High-pressure studies of iron bearing spinels attract extensive attention in order to understand strong electronic correlation such as the charge transfer, electron hopping, electron high-low spin transition, Jahn-Teller distortion and charge disproponation in the lower mantle or subduction zone [1]. Experiment Structure transitions of Fe3-xSixO4, Fe3-xTixO4 Fe3-xCrxO4 spinel solid solution have been investigated at high pressure up to 60 GPa by single crystal and powder diffraction studies using synchrotron radiation with diamond anvil cell. X-ray emission experiment (XES) at high pressure proved the spin transition of Fe-Kβ from high spin (HS) to intermediate spin state (IS) or low spin state (LS). Mössbauer experiment and Raman spectra study have been also conducted for deformation analysis of Fe site and confirmation of the configuration change of Fe atoms. Jahn-Teller effect A cubic-to-tetragonal transition under pressure was induced by Jahn-Teller effect of IVFe2+ (3d6) in the tetrahedral site of Fe2TiO4 and FeCr2O4, providing the transformation from 43m (Td) to 42m (D2d). Tetragonal phase is formed by the degeneracy of e orbital of Fe2+ ion. Their c/a ratios are c/a<1 due to dx2-y2 orbital of the electronic tetrahedral configuration. However, Fe3O4 (I), Fe2SiO4 (N), do not have a tetragonal polymorph because of no IVFe2+ ion [2]. Spin transition HS-to-LS transition starts from 15.6GPa in Fe3O4, 19.6 GPa in Fe2TiO4, 17GPa in Fe2SiO4. The transition is more capable due to VIFe2+ in the octahedral site. The extremely shortened octahedral bonds result in a distortion of 8-fold cation site. This structure change is accelerated by HS-LS transition of Fe2+ in the 8-fold coordination site. Post spinel transition The transition to orthorhombic post-spinel structure with Cmcm has

  15. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    DOEpatents

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  16. Synthesis, spectroscopy, and hydrogen/deuterium exchange in high-spin iron(II) hydride complexes.

    PubMed

    Dugan, Thomas R; Bill, Eckhard; MacLeod, K Cory; Brennessel, William W; Holland, Patrick L

    2014-03-03

    Very few hydride complexes are known in which the metals have a high-spin electronic configuration. We describe the characterization of several high-spin iron(II) hydride/deuteride isotopologues and their exchange reactions with one another and with H2/D2. Though the hydride/deuteride signal is not observable in NMR spectra, the choice of isotope has an influence on the chemical shifts of distant protons in the dimers through the paramagnetic isotope effect on chemical shift. This provides the first way to monitor the exchange of H and D in the bridging positions of these hydride complexes. The rate of exchange depends on the size of the supporting ligand, and this is consistent with the idea that H2/D2 exchange into the hydrides occurs through the dimeric complexes rather than through a transient monomer. The understanding of H/D exchange mechanisms in these high-spin iron hydride complexes may be relevant to postulated nitrogenase mechanisms.

  17. Unconventional normal-state spin dynamics in underdoped high-Tc cuprates as a fingerprint of spiral correlations of localized spins and dual localized/itinerant nature of spin fluctuations

    NASA Astrophysics Data System (ADS)

    Onufrieva, F.

    2017-03-01

    The paper is motivated by the observation of unusual and not well understood spin dynamics in low- and moderately doped high-Tc cuprates as well as by the discovery in these materials of a static incommensurate order for doping exceeding the insulator-metal boundary in the phase diagram. We develop a microscopic approach that allows us to treat accurately the quantum fluctuations in the spiral state developing upon doping the Mott-Neel insulator. We show that the spiral order of localized spins induces an off-diagonal order of mobile charges and a gap Δ ∝|Q | in their spectrum (Q is the spiral incommensurability wave vector defined with respect to QAF). Due to the dynamic spin-charge interaction the latter gap produces a feedback effect consisting in the appearence of a gap in the coherent spin excitation spectrum. As a result, the characteristic energy ωc=Δ appears, in the spin excitation spectra. It separates two components with qualitatively different behavior-above ωc, spin excitations are magnonlike and have an upward dispersion, below it, they are of the relaxation type and have a slight downward dispersion. The form of the dispersion is close to the form observed experimentally (by inelastic neutron scattering), which can be characterized as OPEN-hour-glass shaped or Y -shaped. There is no qualitative difference between the spin dynamics in the normal and SC states as far as doping is relatively low. There is no resonance. Other important features, including the incommensurability and uniaxial anisotropy of the low-energy spin excitations and the doping dependencies of the characteristic energy and wave vectors, are also close to those observed experimentally in low-doped cuprates. We show that the static spiral state becomes unstable at the critical doping nc. We show also that adopting the hypothesis about the presence of finite-energy spiral correlations in the paramagnetic state above nc and based on the results obtained for the static spiral state

  18. Spin states of FeOOH at high pressure using x-ray emission spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Mao, W. L.; Gleason, A. E.; Pentcheva, R.; Otte, K.; Suzuki, A.

    2011-12-01

    Electronic spin transitions in alpha-FeOOH (goethite) and high-pressure phase epsilon-FeOOH were monitored using high pressure x-ray emission spectroscopy. A high- to low-spin transition in trivalent iron was found in synthesized epsilon-FeOOH on compression at 56.8 GPa, which returned to high-spin on decompression at 20 GPa. This corroborates density-functional theory (DFT) calculations with an on-site Coulomb repulsion term (GGA+U) predict the transition to occur at 56.6 GPa. Compression of alpha-FeOOH to 60 GPa did not show any high- to low-spin transition consistent with the DFT results. Monitoring the spin states of iron-oxy-hydroxides as a function of pressure gives insight into the relationship between electronic spin transitions and structural transitions - which has previously been studied in other key mantle minerals, including iron-bearing perovskites and ferropericlase. Furthermore, this may help uncover a connection between water content (presence of hydroxyl) in a mineral and Fe3+ spin-transition pressure at mid- to lower-mantle conditions in the Earth.

  19. Magic angle spinning NMR of proteins: high-frequency dynamic nuclear polarization and (1)H detection.

    PubMed

    Su, Yongchao; Andreas, Loren; Griffin, Robert G

    2015-01-01

    Magic angle spinning (MAS) NMR studies of amyloid and membrane proteins and large macromolecular complexes are an important new approach to structural biology. However, the applicability of these experiments, which are based on (13)C- and (15)N-detected spectra, would be enhanced if the sensitivity were improved. Here we discuss two advances that address this problem: high-frequency dynamic nuclear polarization (DNP) and (1)H-detected MAS techniques. DNP is a sensitivity enhancement technique that transfers the high polarization of exogenous unpaired electrons to nuclear spins via microwave irradiation of electron-nuclear transitions. DNP boosts NMR signal intensities by factors of 10(2) to 10(3), thereby overcoming NMR's inherent low sensitivity. Alternatively, it permits structural investigations at the nanomolar scale. In addition, (1)H detection is feasible primarily because of the development of MAS rotors that spin at frequencies of 40 to 60 kHz or higher and the preparation of extensively (2)H-labeled proteins.

  20. Pseudo-continuous arterial spin labeling technique for measuring CBF dynamics with high temporal resolution.

    PubMed

    Silva, A C; Kim, S G

    1999-09-01

    Cerebral blood flow (CBF) can be measured noninvasively with nuclear magnetic resonance (NMR) by using arterial water as an endogenous perfusion tracer. However, the arterial spin labeling (ASL) techniques suffer from poor temporal resolution due to the need to wait for the exchange of labeled arterial spins with tissue spins to produce contrast. In this work, a new ASL technique is introduced, which allows the measurement of CBF dynamics with high temporal and spatial resolution. This novel method was used in rats to determine the dynamics of CBF changes elicited by somatosensory stimulation with a temporal resolution of 108 ms. The onset time of the CBF response was 0.6 +/- 0.4 sec (mean +/- SD) after onset of stimulation (n = 10). The peak response was observed 4.4 +/- 3.7 sec (mean +/- SD) after stimulation began. These results are in excellent agreement with previous data obtained with invasive techniques, such as laser-Doppler flowmetry and hydrogen clearance, and suggest the appropriateness of this novel technique to probe CBF dynamics in functional and pathological studies with high temporal and spatial resolution. Magn Reson Med 42:425-429, 1999.

  1. Probing the dynamics of high-viscosity entangled polymers under shear using Neutron Spin Echo spectroscopy

    NASA Astrophysics Data System (ADS)

    Kawecki, M.; Gutfreund, P.; Adlmann, F. A.; Lindholm, E.; Longeville, S.; Lapp, A.; Wolff, M.

    2016-09-01

    Neutron Spin Echo spectroscopy provides unique insight into molecular and submolecular dynamics as well as intra- and inter-molecular interactions in soft matter. These dynamics may change drastically under shear flow. In particular in polymer physics a stress plateau is observed, which might be explained by an entanglement-disentanglement transition. However, such a transition is difficult to identify directly by experiments. Neutron Spin Echo has been proven to provide information about entanglement length and degree by probing the local dynamics of the polymer chains. Combining shear experiments and neutron spin echo is challenging since, first the beam polarisation has to be preserved during scattering and second, Doppler scattered neutrons may cause inelastic scattering. In this paper we present a new shear device adapted for these needs. We demonstrate that a high beam polarisation can be preserved and present first data on an entangled polymer solution under shear. To complement the experiments on the dynamics we present novel SANS data revealing shear- induced conformational changes in highly entangled polymers.

  2. High-spin magnetic states in the two-orbital Hubbard model on a tetrahedron.

    PubMed

    Romano, Alfonso; Noce, Canio; Amendola, Maria Emilia

    2008-11-19

    We present a study of the two-orbital degenerate Hubbard model in which the exact numerical solution on a regular tetrahedron is obtained via suitable implementation of the symmetries generated by the spin, the pairing and the orbital pseudospin operators. In particular, we show that a large variety of high-spin magnetic ground states can develop away from half filling, depending on the values of the electron density and the parameters of the model. As the tetrahedron is the simplest finite-size cluster where hopping processes connect all pairs of sites with constant probability, the study is extended by providing the exact analytical solution of the model on an infinite lattice in the unconstrained hopping limit.

  3. Finding new superconductors: the spin-fluctuation gateway to high Tc and possible room temperature superconductivity.

    PubMed

    Pines, David

    2013-10-24

    We propose an experiment-based strategy for finding new high transition temperature superconductors that is based on the well-established spin fluctuation magnetic gateway to superconductivity in which the attractive quasiparticle interaction needed for superconductivity comes from their coupling to dynamical spin fluctuations originating in the proximity of the material to an antiferromagnetic state. We show how lessons learned by combining the results of almost three decades of intensive experimental and theoretical study of the cuprates with those found in the decade-long study of a strikingly similar family of unconventional heavy electron superconductors, the 115 materials, can prove helpful in carrying out that search. We conclude that, since Tc in these materials scales approximately with the strength of the interaction, J, between the nearest neighbor local moments in their parent antiferromagnetic state, there may not be a magnetic ceiling that would prevent one from discovering a room temperature superconductor.

  4. Simulating a High-Spin Black Hole-Neutron Star Binary

    NASA Astrophysics Data System (ADS)

    Derby, John; Lovelace, Geoffrey; Duez, Matt; Foucart, Francois; Simulating Extreme Spacetimes (SXS) Collaboration

    2017-01-01

    During their first observing run (fall 2015) Advanced LIGO detected gravitational waves from merging black holes. In its future observations LIGO could detect black hole neutron star binaries (BHNS). It is important to have numerical simulations to predict these waves, to help find as many of these waves as possible and to estimate the sources properties, because at times near merger analytic approximations fail. Also, numerical models of the disk formed when the black hole tears apart the neutron star can help us learn about these systems' potential electromagnetic counterparts. One area of the parameter space for BHNS systems that is particularly challenging is simulations with high black hole spin. I will present results from a new BHNS simulation that has a black hole spin of 90% of the theoretical maximum. We are part of SXS but not all.

  5. Probing Spin Frustration in High-symmetry Magnetic Nanomolecules by Inelastic Neutron Scattering

    SciTech Connect

    Garlea, Vasile O; Nagler, Stephen E; Zarestky, Jerel L; Stassis, C.; Vaknin, D.; Kogerler, P.; McMorrow, D. F.; Niedermayer, C.; Tennant, D. A.; Lake, B.; Qiu, Y.; Exler, M.; Schnack, J.; Luban, M.

    2006-01-01

    Low temperature inelastic neutron scattering studies have been performed to characterize the low energy magnetic excitation spectrum of the magnetic nanomolecule {l_brace}Mo{sub 72}Fe{sub 30}{r_brace}. This unique highly symmetric cluster features spin frustration and is one of the largest discrete magnetic molecules studied to date by inelastic neutron scattering. The 30 s=5/2 Fe{sup III} ions, embedded in a spherical polyoxomolybdate molecule, occupy the vertices of an icosidodecahedron and are coupled via nearest-neighbor antiferromagnetic interactions. The overall energy scale of the excitation and the gross features of the temperature dependence of the observed neutron scattering are explained by a quantum model of the frustrated spin cluster. However, no satisfactory theoretical explanation is yet available for the observed magnetic field dependence.

  6. Spin polarization in high density quark matter under a strong external magnetic field

    NASA Astrophysics Data System (ADS)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança; Yamamura, Masatoshi; Bohr, Henrik

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interaction under the strong external magnetic field, it is shown that a quark spin polarized phase is realized in all regions of the quark chemical potential under consideration within the lowest Landau level approximation. In the axial-vector-type interaction, it is also shown that the quark spin polarized phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs.

  7. High-temperature heat capacity of Co3O4 spinel: thermally induced spin unpairing transition

    USGS Publications Warehouse

    Mocala, K.; Navrotsky, A.; Sherman, David M.

    1992-01-01

    A strong anomaly was found in the heat capacity of Co3O4 between 1000 K and the decomposition temperature. This anomaly is not related to the decomposition of Co3O4 to CoO. The measured entropy of transition, ??S=46??4 J mol-1 K-1 of Co3O4, supports the interpretation that this anomaly reflects a spin unpairing transition in octahedrally coordinated Co3+ cations. Experimental values of heat capacity, heat content and entropy of Co3O4 in the high temperature region are provided. The enthalpy of the spin unpairing transition is 53??4 kJ mol-1 of Co3O4. ?? 1992 Springer-Verlag.

  8. Odd tensor electric transitions in high-spin Sn-isomers and generalized seniority

    NASA Astrophysics Data System (ADS)

    Maheshwari, Bhoomika; Jain, Ashok Kumar

    2016-02-01

    The similar behavior of the B (E 1) values of the recently observed 13- odd tensor E1 isomers and the B (E 2) values of the 10+ and 15- even tensor E2 isomers in the Sn-isotopes has been understood in terms of the generalized seniority for multi-j orbits by using the quasi-spin scheme. This simple approach proves to be quite successful in explaining the measured transition probabilities and the corresponding half-lives in the high-spin isomers of the semi-magic Sn-isotopes. Hence, we show for the first time the occurrence of seniority isomers in the 13- Sn-isomers, which decay by odd-tensor E1 transitions to the same seniority states.

  9. Broadband magnetoelastic coupling in magnonic-phononic crystals for high-frequency nanoscale spin-wave generation

    NASA Astrophysics Data System (ADS)

    Graczyk, Piotr; Kłos, Jarosław; Krawczyk, Maciej

    2017-03-01

    Spin waves are promising candidates for information carriers in advanced technology. The interactions between spin waves and acoustic waves in magnetic nanostructures are of much interest because of their potential application for spin-wave generation, amplification, and transduction. We investigate numerically the dynamics of magnetoelastic excitations in a one-dimensional magnonic-phononic crystal consisting of alternating layers of permalloy and cobalt. We use the plane-wave method and the finite-element method for frequency- and time-domain simulations, respectively. The studied structure is optimized for hybridization of specific spin-wave and acoustic dispersion branches in the entire Brillouin zone in a broad frequency range. We show that this type of periodic structure can be used for efficient generation of high-frequency spin waves.

  10. High-temperature series expansion for spin-1/2 Heisenberg models

    NASA Astrophysics Data System (ADS)

    Hehn, Andreas; van Well, Natalija; Troyer, Matthias

    2017-03-01

    We present a high-temperature series expansion code for spin-1/2 Heisenberg models on arbitrary lattices. As an example we demonstrate how to use the application for an anisotropic triangular lattice with two independent couplings J1 and J2 and calculate the high-temperature series of the magnetic susceptibility and the static structure factor up to 12th and 10th order, respectively. We show how to extract effective coupling constants for the triangular Heisenberg model from experimental data on Cs2CuBr4.

  11. Highly Flexible Indium Tin Oxide Nanofiber Transparent Electrodes by Blow Spinning.

    PubMed

    Wang, Haolun; Liao, Suiyang; Bai, Xiaopeng; Liu, Zhenglian; Fang, Minghao; Liu, Tao; Wang, Ning; Wu, Hui

    2016-12-07

    Transparent conductive film (TCF) has found wide applications. Indium tin oxide (ITO) is currently the most widely used transparent electrode. However, major problem of ITO is the lacking of flexibility, which totally limits its applications. Here, we report a highly flexible transparent electrode consisting of freestanding ITO nanofiber network fabricated by blow spinning, the advantage of which is its high-efficiency, low cost and safety. When the bending radius decreased to 0.5 mm, the resistance of the transparent electrodes only increased by 18.4%. Furthermore, the resistance was almost unchanged after thousands of bending cycles at 3.5 mm bending radius.

  12. A Synthetic High-Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity

    SciTech Connect

    England, J.; Martinho, M; Farquhar, E; Frisch, J; Bominaar, E; Munck, E; Que, L

    2009-01-01

    The high-yield generation of a synthetic high-spin oxoiron(IV) complex, (Fe{sup IV}(O)(TMG{sub 3}tren)){sup 2+} (TMG{sub 3}tren = 1,1,1-tris{l_brace}2-(N2-(1,1,3,3-tetramethylguanidino))ethyl{r_brace}amine), has been achieved by using the very bulky tetradentate TMG{sub 3}tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored.

  13. Reduction of critical current density for out-of-plane mode oscillation in a mag-flip spin torque oscillator using highly spin-polarized Co2Fe(Ga0.5Ge0.5) spin injection layer

    NASA Astrophysics Data System (ADS)

    Bosu, S.; Sepehri-Amin, H.; Sakuraba, Y.; Hayashi, M.; Abert, C.; Suess, D.; Schrefl, T.; Hono, K.

    2016-02-01

    We study spin torque oscillators comprised of a perpendicular spin injection layer (SIL) and a planar field generating layer to reveal the influence of the spin polarization of SIL material on the critical current density, JC, to induce microwave oscillation. Two systems with different SIL are compared: one with a highly spin-polarized Heusler alloy, Co2Fe(Ga0.5Ge0.5) (CFGG), and the other a prototypical Fe2Co alloy. Cross sectional scanning transmission electron microscopy observations show the B2-ordered structure in a 3-nm-thick CFGG SIL, a prerequisite for obtaining half-metallic transport properties. Current induced microwave oscillations are found at frequencies of ˜15 GHz for both systems. However, the current needed to cause the oscillations is ˜50% smaller for films with the CFGG SIL compared to those of the Fe2Co SIL. These results are in accordance with micromagnetic simulations that include spin accumulation at the SIL.

  14. High Antiferromagnetic Domain Wall Velocity Induced by Néel Spin-Orbit Torques

    NASA Astrophysics Data System (ADS)

    Gomonay, O.; Jungwirth, T.; Sinova, J.

    2016-07-01

    We demonstrate the possibility to drive an antiferromagnetic domain wall at high velocities by fieldlike Néel spin-orbit torques. Such torques arise from current-induced local fields that alternate their orientation on each sublattice of the antiferromagnet and whose orientation depends primarily on the current direction, giving them their fieldlike character. The domain wall velocities that can be achieved by this mechanism are 2 orders of magnitude greater than the ones in ferromagnets. This arises from the efficiency of the staggered spin-orbit fields to couple to the order parameter and from the exchange-enhanced phenomena in antiferromagnetic texture dynamics, which leads to a low domain wall effective mass and the absence of a Walker breakdown limit. In addition, because of its nature, the staggered spin-orbit field can lift the degeneracy between two 180° rotated states in a collinear antiferromagnet, and it provides a force that can move such walls and control the switching of the states.

  15. Spin-density-functional theory for imbalanced interacting Fermi gases in highly elongated harmonic traps

    NASA Astrophysics Data System (ADS)

    Gao Xianlong; Asgari, Reza

    2008-03-01

    We numerically study imbalanced two component Fermi gases with attractive interactions in highly elongated harmonic traps. An accurate parametrization formula for the ground state energy is presented for a spin-polarized attractive Gaudin-Yang model. Our studies are based on an accurate microscopic spin-density-functional theory through the Kohn-Sham scheme which employs the one-dimensional homogeneous Gaudin-Yang model with a Luther-Emery-liquid ground-state correlation as a reference system. A Thomas-Fermi approximation is examined incorporating the exchange-correlation interaction. By studying the charge and spin density profiles of the system based on these methods, we gain a quantitative understanding of the role of attractive interactions and polarization on the formation of the two-shell structure, with the coexisted Fulde-Ferrell-Larkin-Ovchinnikov-type phase in the center of the trap and either the BCS superfluid phase or the normal phase at the edges of the trap. Our results are in good agreement with the recent theoretical consequences.

  16. Progress in Neutron Scattering Studies of Spin Excitations in High-Tc Cuprates

    NASA Astrophysics Data System (ADS)

    Fujita, Masaki; Hiraka, Haruhiro; Matsuda, Masaaki; Matsuura, Masato; Tranquada, John M.; Wakimoto, Shuichi; Xu, Guangyong; Yamada, Kazuyoshi

    2012-01-01

    Neutron scattering experiments continue to improve our knowledge of spin fluctuations in layered cuprates, excitations that are symptomatic of the electronic correlations underlying high-temperature superconductivity. Time-of-flight spectrometers, together with new and varied single crystal samples, have provided a more complete characterization of the magnetic energy spectrum and its variation with carrier concentration. While the spin excitations appear anomalous in comparison with simple model systems, there is clear consistency among a variety of cuprate families. Focusing initially on hole-doped systems, we review the nature of the magnetic spectrum, and variations in magnetic spectral weight with doping. We consider connections with the phenomena of charge and spin stripe order, and the potential generality of such correlations as suggested by studies of magnetic-field and impurity induced order. We contrast the behavior of the hole-doped systems with the trends found in the electron-doped superconductors. Returning to hole-doped cuprates, studies of translation-symmetry-preserving magnetic order are discussed, along with efforts to explore new systems. We conclude with a discussion of future challenges.

  17. Bound states in the transfer matrix spectrum for general lattice ferromagnetic spin systems at high temperature

    PubMed

    Schor; O'Carroll

    2000-08-01

    We obtain different properties of general d dimensional lattice ferromagnetic spin systems with nearest neighbor interactions in the high temperature region (beta<1). Each model is characterized by a single site a priori spin distribution, taken to be even. We state our results in terms of the parameter alpha=-3(2) where denotes the kth moment of the a priori distribution. Associated with the model is a lattice quantum field theory that is known to contain particles. We show that for alpha>0, beta small, there exists a bound state with mass below the two-particle threshold. For alpha<0, bound states do not exist. The existence of the bound state has implications on the decay of correlations, i.e., the four-point function decays at a slower rate than twice that of the two-point function. These results are obtained using a lattice version of the Bethe-Salpeter equation in the ladder approximation. The existence and nonexistence results generalize to N-component models with rotationally invariant a priori spin distributions.

  18. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    PubMed Central

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-01-01

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whose primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y PMID:26039222

  19. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    DOE PAGES

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-06-03

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whosemore » primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y« less

  20. A new architecture for high spin organics based on Baird's rule of 4n electron triplet aromatics.

    PubMed

    Mauksch, Michael; Tsogoeva, Svetlana B

    2017-02-08

    Due to the absence of open subshells (unlike transition metal compounds), stable high spin organic molecules are rare and are mostly limited to states of low multiplicity. As an alternative to high multiplicity polyradicals and polycarbenes, with their small energetic separation of different spin isomers, it is demonstrated that Baird's rule of 4n electron aromaticity in the triplet electronic state allows, in principle, the design of polycyclic high spin organics with high spin multiplicity in the electronic ground state and a large energetic separation for other spin states. Energy spacing between spin isomers is dictated here by the aromaticity or antiaromaticity of individual cycles (taking into account all π electrons), rather than by a spin Hamiltonian alone (accounting only for unpaired spin electrons). As a proof of concept, dyads of the cyclopentadienyl cation (which has been reported to possess a triplet ground state) have been computationally found to possess a quintet electronic ground state with two ferromagnetically coupled Baird aromatic rings (with SCF-GIAO NICS(0) = -4.6 and -4.4, respectively; "NICS" is "nucleus independent chemical shift") at the CASMP2(8,10)/6-311G*//CASSCF(8,10)/6-311G* level, which is 48.3 kcal mol(-1) lower in energy than the C2 open shell singlet with two antiaromatic rings (with NICS = +17.4), and 19.7 kcal mol(-1) below the triplet which has one aromatic and one antiaromatic ring, with NICS = -4.8 and +45.0, respectively. Triads of the cyclopentadienyl cation in linear and branched topologies are also proposed to be ground states of maximum spin multiplicity by computations at the DFT and CCSD(T)/6-31G//UB3LYP/6-311G* levels.

  1. Polarization measurements and high-spin states in 8638Sr48

    NASA Astrophysics Data System (ADS)

    Kumar, Naveen; Kumar, Suresh; Kumar, V.; Mandal, S. K.; Palit, R.; Saha, S.; Sethi, J.; Trivedi, T.; Pancholi, S. C.; Srivastava, P. C.

    2016-11-01

    The high-spin states in 86Sr nucleus were populated using the 76Ge(13C, 3n) reaction at a beam energy of 45 MeV. The γ-γ and γ-γ-γ coincidence measurements were used to establish the level scheme up to 10.9 MeV excitation energy and spin Iπ =19+. In our preliminary results reported earlier, a positive-parity dipole (ΔI = 1) band based on the 6878-keV level having M1 γ-ray transitions was identified. In the present work, the γ-rays and their sequence have been established for this band. The band may have a magnetic rotational character. The spin-parity of the levels were assigned by measuring the Directional Correlations of the Oriented (DCO) nuclei and the polarization asymmetry. The polarization measurements were performed for the first time for the γ-ray transitions in this nucleus. The experimental band structures were compared with the shell-model calculations using two recent effective interactions, JUN45 and jj44b in the 1p3/2, 0f5/2, 1p1/2, 0g9/2 model space. From the Tilted-Axis Cranking (TAC) calculations, the 4-qp π(g9/2) 2 ⊗ ν(g9/2) - 2 configuration is suggested for the lower-part of the (ΔI = 1) band up to spin Iπ =16+ and the 6-qp π [(g9/2) 2(f5/2) 1(p1/2) 1 ] ⊗ ν(g9/2) - 2 configuration for the upper-part of the band.

  2. Synthesis and DNA cleavage activities of mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes which linked with uracil.

    PubMed

    Wang, Xiao-Yan; Zhang, Ji; Li, Kun; Jiang, Ning; Chen, Shan-Yong; Lin, Hong-Hui; Huang, Yu; Ma, Li-Jian; Yu, Xiao-Qi

    2006-10-01

    Mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes, which could attach to peptide nucleic acid (PNA), were synthesized as DNA cleavage agents. The structures of these new mononuclear complexes were identified by MS and (1)H NMR spectroscopy. The catalytic activities on DNA cleavage of these mononuclear complexes with different central metals were subsequently studied, which showed that copper complex was better catalyst in the DNA cleavage process than zinc and cobalt complexes. The effects of reaction time, concentration of complexes were also investigated. The results indicated that the copper(II) complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA) (Form I) under physiological conditions to produce selectively nicked DNA (Form II, no Form III produced) with high yields. The mechanism of the cleavage process was also studied.

  3. spin pumping occurred under nonlinear spin precession

    NASA Astrophysics Data System (ADS)

    Zhou, Hengan; Fan, Xiaolong; Ma, Li; Zhou, Shiming; Xue, Desheng

    Spin pumping occurs when a pure-spin current is injected into a normal metal thin layer by an adjacent ferromagnetic metal layer undergoing ferromagnetic resonance, which can be understood as the inverse effect of spin torque, and gives access to the physics of magnetization dynamics and damping. An interesting question is that whether spin pumping occurring under nonlinear spin dynamics would differ from linear case. It is known that nonlinear spin dynamics differ distinctly from linear response, a variety of amplitude dependent nonlinear effect would present. It has been found that for spin precession angle above a few degrees, nonlinear damping term would present and dominated the dynamic energy/spin-moment dissipation. Since spin pumping are closely related to the damping process, it is interesting to ask whether the nonlinear damping term could be involved in spin pumping process. We studied the spin pumping effect occurring under nonlinear spin precession. A device which is a Pt/YIG microstrip coupled with coplanar waveguide was used. High power excitation resulted in spin precession entering in a nonlinear regime. Foldover resonance lineshape and nonlinear damping have been observed. Based on those nonlinear effects, we determined the values of the precession cone angles, and the maximum cone angle can reach a values as high as 21.5 degrees. We found that even in nonlinear regime, spin pumping is still linear, which means the nonlinear damping and foldover would not affect spin pumping process.

  4. High-spin states in 136La and possible structure change in the N =79 region

    NASA Astrophysics Data System (ADS)

    Nishibata, H.; Leguillon, R.; Odahara, A.; Shimoda, T.; Petrache, C. M.; Ito, Y.; Takatsu, J.; Tajiri, K.; Hamatani, N.; Yokoyama, R.; Ideguchi, E.; Watanabe, H.; Wakabayashi, Y.; Yoshinaga, K.; Suzuki, T.; Nishimura, S.; Beaumel, D.; Lehaut, G.; Guinet, D.; Desesquelles, P.; Curien, D.; Higashiyama, K.; Yoshinaga, N.

    2015-05-01

    High-spin states in the odd-odd nucleus 136La, which is located close to the β -stability line, have been investigated in the radioactive-beam-induced fusion-evaporation reaction 124Sn(17N,5 n ). The use of the radioactive beam enabled a highly sensitive and successful search for a new isomer [14+,T1 /2=187 (27 ) ns] in 136La. In the A =130 -140 mass region, no such long-lived isomer has been observed at high spin in odd-odd nuclei. The 136La level scheme was revised, incorporating the 14+ isomer and six new levels. The results were compared with pair-truncated shell model (PTSM) calculations which successfully explain the level structure of the π h11 /2⊗ν h11/2 -1 bands in 132La and 134La. The isomerism of the 14+ state was investigated also by a collective model, the cranked Nilsson-Strutinsky (CNS) model, which explains various high-spin structures in the medium-heavy mass region. It is suggested that a new type of collective structure is induced in the PTSM model by the increase of the number of π g7 /2 pairs, and/or in the CNS model by the configuration change associated with the shape change in 136La.

  5. Highly spin-polarized materials and devices for spintronics(∗).

    PubMed

    Inomata, Koichiro; Ikeda, Naomichi; Tezuka, Nobuki; Goto, Ryogo; Sugimoto, Satoshi; Wojcik, Marek; Jedryka, Eva

    2008-01-01

    The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD) using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co2Cr1 - x Fe x Al (CCFA(x)) and Co2FeSi1 - x Al x (CFSA(x)) and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR) of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs) using Co2FeSi0.5Al0.5 (CFSA(0.5)) Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5) at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001) substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5) electrodes depends on the structure, and is significantly higher for L21 than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe2 film deposited on a MgO (001) single crystal substrate, wherein the spinel structure of CoFe2O4 (CFO

  6. Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)

    SciTech Connect

    Tobin, James; Yu, Sung Woo; Morton, Simon; Waddill, George; Thompson, Jamie; Neal, James; Spangenberg, Matthais; Shen, T.H.

    2009-05-19

    Highly spin-polarized sources of electrons, Integrated into device design, remain of great interest to the spintronic and magneto-electronic device community Here, the growth of Fe upon GaAs(001) has been studied with photoelectron spectroscopy (PES), including Spin Resolved PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of alpha-Fe(001), with a bcc real space ordering, Is obtained The results will be discussed in light of the possibility of using such films as a spin-polarized source in device applications.

  7. Octahedral-tetrahedral equilibrium and solvent exchange of cobalt(II) ions in primary alkylamines.

    PubMed

    Aizawa, Sen-ichi; Funahashi, Shigenobu

    2002-08-26

    The enthalpy differences (Delta H degrees ) of the equilibrium between the octahedral and tetrahedral solvated cobalt(II) complexes were obtained in some primary alkylamines such as propylamine (pa, 36.1 +/- 2.3 kJ mol(-1)), n-hexylamine (ha, 34.9 +/- 1.0 kJ mol(-1)), 2-methoxyethylamine (meea, 44.8 +/- 3.1 kJ mol(-1)), and benzylamine (ba, 50.1 +/- 3.6 kJ mol(-1)) by the spectrophotometric method. The differences in the energy levels between the two geometries of the cobalt(II) complexes in the spherically symmetric field (Delta E(spher)) were estimated from the values of Delta H degrees by offsetting the ligand field stabilization energies. It was indicated that the value of Delta E(spher) is the decisive factor in determining the value of Delta H degrees and is largely dependent on the electronic repulsion between the d-electrons and the donor atoms and the interelectronic repulsion in the d orbitals. The comparison between activation enthalpies (Delta H(++)) for the solvent exchange reactions of octahedral cobalt(II) ions in pa and meea revealed that the unexpectedly large rate constant and small Delta H(++) in pa are attributed to the strong electronic repulsion in the ground state and removal of the electronic repulsion in the dissociative transition state, which can give the small Delta E(spher) between the ground and transition states. Differences in the solvent exchange rates and the DeltaH(++) values of the octahedral metal(II) ions in some other solvents are discussed in connection with the electronic repulsive factors.

  8. Isospin Symmetry at High Spin Studied via Nucleon Knockout from Isomeric States.

    PubMed

    Milne, S A; Bentley, M A; Simpson, E C; Baugher, T; Bazin, D; Berryman, J S; Bruce, A M; Davies, P J; Diget, C Aa; Gade, A; Henry, T W; Iwasaki, H; Lemasson, A; Lenzi, S M; McDaniel, S; Napoli, D R; Nichols, A J; Ratkiewicz, A; Scruton, L; Stroberg, S R; Tostevin, J A; Weisshaar, D; Wimmer, K; Winkler, R

    2016-08-19

    One-neutron knockout reactions have been performed on a beam of radioactive ^{53}Co in a high-spin isomeric state. The analysis is shown to yield a highly selective population of high-spin states in an exotic nucleus with a significant cross section, and hence represents a technique that is applicable to the planned new generation of fragmentation-based radioactive beam facilities. Additionally, the relative cross sections among the excited states can be predicted to a high level of accuracy when reliable shell-model input is available. The work has resulted in a new level scheme, up to the 11^{+} band-termination state, of the proton-rich nucleus ^{52}Co (Z=27, N=25). This has in turn enabled a study of mirror energy differences in the A=52 odd-odd mirror nuclei, interpreted in terms of isospin-nonconserving (INC) forces in nuclei. The analysis demonstrates the importance of using a full set of J-dependent INC terms to explain the experimental observations.

  9. Spin-symmetry conversion and internal rotation in high J molecular systems

    NASA Astrophysics Data System (ADS)

    Mitchell, Justin; Harter, William

    2006-05-01

    Dynamics and spectra of molecules with internal rotation or rovibrational coupling is approximately modeled by rigid or semi-rigid rotors with attached gyroscopes. Using Rotational Energy (RE)^1 surfaces, high resolution molecular spectra for high angular momentum show two distinct but related phenomena; spin-symmetry conversion and internal rotation. For both cases the high total angular momentum allows for transitions that would otherwise be forbidden. Molecular body-frame J-localization effects associated with tight energy level-clusters dominate the rovibronic spectra of high symmetry molecules, particularly spherical tops at J>10. ^2 The effects include large and widespread spin-symmetry mixing contrary to conventional wisdom^3 about weak nuclear moments. Such effects are discussed showing how RE surface plots may predict them even at low J. Classical dynamics of axially constrained rotors are approximated by intersecting rotational-energy-surfaces (RES) that have (J-S).B.(J-S) forms in the limit of constraints that do no work. Semi-classical eigensolutions are compared to those found by direct diagonalization. ^1 W.G Hater, in Handbook of Atomic, Molecular and Optical Physics, edited by G.W.F Drake (Springer, Germany 2006) ^2 W. G. Harter, Phys. Rev. A24,192-262(1981). ^3 G. Herzberg, Infrared and Raman Spectra (VanNostrand 1945) pp. 458,463.

  10. High-Spin States in PALLADIUM-107, PALLADIUM-108 and SILVER-109.

    NASA Astrophysics Data System (ADS)

    Pohl, Kenneth R.

    1995-01-01

    High-spin states in ^{107,108 }Pd and ^{109}Ag have been studied by charged-particle-gamma , gamma-gamma , and charged-particle-gamma -gamma coincidence measurements of heavy-ion fusion-evaporation reactions. Charged-particle -gamma measurements of gamma -ray spectra, angular distributions, and excitation functions were performed using an ^{18 }O beam with an enriched ^{96 }Zr target at beam energies of 56, 63, 72, and 80 MeV. Background measurements were performed using a ^{rm nat}Zr target. Charged -particle-gamma-gamma measurements using the same reaction at beam energies of 70 and 60 MeV were used to measure gamma -gamma coincidences, coincidence intensities, and gated angular distributions. A gamma-gamma measurement using the reaction ^{100}Mo( ^{13}C,p3n)^ {109}Ag at E_{BEAM } = 65 MeV was performed to measure a low-energy transition in ^{109}Ag. Partial level schemes of ^{107,108 }Pd and ^{109}Ag were constructed from the gamma- gamma coincidence measurements. These levels schemes significantly extend the known high-spin decay patterns of ^{107}Pd and ^{108}Pd. The ^{109}Ag results represent the first measurement of high-spin states in that nuclide. New collective bands have been discovered in all three nuclides. The principal bands in each exhibit the general property of back-bends corresponding to the rotational alignment of a pair of h_{11over2 } quasi-neutrons. Rotational alignments and Routhians have been compared to predictions of the cranked shell model and total Routhian surface calculations. Transition properties in ^{107}Pd and ^{109}Ag have been compared to predictions of a geometrical model in the context of the cranked shell model.

  11. Domain wall spin structures in mesoscopic Fe rings probed by high resolution SEMPA

    NASA Astrophysics Data System (ADS)

    Krautscheid, Pascal; Reeve, Robert M.; Lauf, Maike; Krüger, Benjamin; Kläui, Mathias

    2016-10-01

    We present a combined theoretical and experimental study of the energetic stability and accessibility of different domain wall spin configurations in mesoscopic magnetic iron rings. The evolution is investigated as a function of the width and thickness in a regime of relevance to devices, while Fe is chosen as a material due to its simple growth in combination with attractive magnetic properties including high saturation magnetization and low intrinsic anisotropy. Micromagnetic simulations are performed to predict the lowest energy states of the domain walls, which can be either the transverse or vortex wall spin structure, in good agreement with analytical models, with further simulations revealing the expected low temperature configurations observable on relaxation of the magnetic structure from saturation in an external field. In the latter case, following the domain wall nucleation process, transverse domain walls are found at larger widths and thicknesses than would be expected by just comparing the competing energy terms demonstrating the importance of metastability of the states. The simulations are compared to high spatial resolution experimental images of the magnetization using scanning electron microscopy with polarization analysis to provide a phase diagram of the various spin configurations. In addition to the vortex and simple symmetric transverse domain wall, a significant range of geometries are found to exhibit highly asymmetric transverse domain walls with properties distinct from the symmetric transverse wall. Simulations of the asymmetric walls reveal an evolution of the domain wall tilting angle with ring thickness which can be understood from the thickness dependencies of the contributing energy terms. Analysis of all the data reveals that in addition to the geometry, the influence of materials properties, defects and thermal activation all need to be taken into account in order to understand and reliably control the experimentally accessible

  12. Spin-on metal oxide materials with high etch selectivity and wet strippability

    NASA Astrophysics Data System (ADS)

    Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

    2016-03-01

    Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

  13. High-Q filters with complete transports using quasiperiodic rings with spin-orbit interaction

    SciTech Connect

    Qiu, R. Z.; Chen, C. H.; Tsao, C. W.; Hsueh, W. J.

    2014-09-15

    A high Q filter with complete transports is achieved using a quasiperiodic Thue-Morse array of mesoscopic rings with spin-orbit interaction. As the generation order of the Thue-Morse array increases, not only does the Q factor of the resonance peak increase exponentially, but the number of sharp resonance peaks also increases. The maximum Q factor for the electronic filter of a Thue-Morse array is much greater than that in a periodic array, for the same number of the rings.

  14. High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

    NASA Astrophysics Data System (ADS)

    Galanakis, I.

    2015-03-01

    Half-metallic Co2MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co2MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co2MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices.

  15. High-spin Fe2+ and Fe3+ in single-crystal aluminous bridgmanite in the lower mantle

    NASA Astrophysics Data System (ADS)

    Lin, Jung-Fu; Mao, Zhu; Yang, Jing; Liu, Jin; Xiao, Yuming; Chow, Paul; Okuchi, Takuo

    2016-07-01

    Spin and valence states of iron in single-crystal bridgmanite (Mg0.89Fe0.12Al0.11Si0.89O3) are investigated using X-ray emission and Mössbauer spectroscopies with laser annealing up to 115 GPa. The results show that Fe predominantly substitutes for Mg2+ in the pseudo-dodecahedral A site, in which 80% of the iron is Fe3+ that enters the lattice via the charge-coupled substitution with Al3+ in the octahedral B site. The total spin momentum and hyperfine parameters indicate that these ions remain in the high-spin state with Fe2+ having extremely high quadrupole splitting due to lattice distortion. (Al,Fe)-bearing bridgmanite is expected to contain mostly high-spin, A-site Fe3+, together with a smaller amount of A-site Fe2+, that remains stable throughout the region. Even though the spin transition of B-site Fe3+ in bridgmanite was reported to cause changes in its elasticity at high pressures, (Fe,Al)-bearing bridgmanite with predominantly A-site Fe will not exhibit elastic anomalies associated with the spin transition.

  16. Coexistence of perfect spin filtering for entangled electron pairs and high magnetic storage efficiency in one setup

    PubMed Central

    Ji, T. T.; Bu, N.; Chen, F. J.; Tao, Y. C.; Wang, J.

    2016-01-01

    For Entangled electron pairs superconducting spintronics, there exist two drawbacks in existing proposals of generating entangled electron pairs. One is that the two kinds of different spin entangled electron pairs mix with each other. And the other is a low efficiency of entanglement production. Herein, we report the spin entanglement state of the ferromagnetic insulator (FI)/s-wave superconductor/FI structure on a narrow quantum spin Hall insulator strip. It is shown that not only the high production of entangled electron pairs in wider energy range, but also the perfect spin filtering of entangled electron pairs in the context of no highly spin-polarized electrons, can be obtained. Moreover, the currents for the left and right leads in the antiferromagnetic alignment both can be zero, indicating 100% tunnelling magnetoresistance with highly magnetic storage efficiency. Therefore, the spin filtering for entangled electron pairs and magnetic storage with high efficiencies coexist in one setup. The results may be experimentally demonstrated by measuring the tunnelling conductance and the noise power. PMID:27074893

  17. Competing decay modes of a high-spin isomer in the proton-unbound nucleus ¹⁵⁸Ta*

    DOE PAGES

    Carroll, R. J.; Page, R. D.; Joss, D. T.; ...

    2015-01-01

    An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus 158Ta. This state was observed to decay by both α and γ decay modes. The large spin change required to decay via γ-ray emission incurs a lifetime long enough for α decay to compete. The α decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) μs and changes the spin by 11ℏ. In this study, additional evidence supporting the assignment of this α decay to the high-spin isomer in 158Ta will bemore » presented.« less

  18. Competing decay modes of a high-spin isomer in the proton-unbound nucleus ¹⁵⁸Ta*

    SciTech Connect

    Carroll, R. J.; Page, R. D.; Joss, D. T.; Uusitalo, J.; Darby, I. G.; Andgren, K.; Cederwall, B.; Eeckhaudt, S.; Grahn, T.; Gray-Jones, C.; Greenlees, P. T.; Hadinia, B.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppänen, A. -P.; Nyman, M.; O'Donnell, D.; Pakarinen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Seweryniak, D.; Simpson, J.

    2015-01-01

    An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus 158Ta. This state was observed to decay by both α and γ decay modes. The large spin change required to decay via γ-ray emission incurs a lifetime long enough for α decay to compete. The α decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) μs and changes the spin by 11ℏ. In this study, additional evidence supporting the assignment of this α decay to the high-spin isomer in 158Ta will be presented.

  19. Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

    NASA Astrophysics Data System (ADS)

    Lesne, E.; Fu, Yu; Oyarzun, S.; Rojas-Sánchez, J. C.; Vaz, D. C.; Naganuma, H.; Sicoli, G.; Attané, J.-P.; Jamet, M.; Jacquet, E.; George, J.-M.; Barthélémy, A.; Jaffrès, H.; Fert, A.; Bibes, M.; Vila, L.

    2016-12-01

    The spin-orbit interaction couples the electrons’ motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism--the Rashba effect--in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.

  20. Structure of high spin state in proton-rich 74,76,78Kr isotopes: A projected shell model description

    NASA Astrophysics Data System (ADS)

    Liu, YanXin; Yu, ShaoYing; Shen, CaiWan

    2015-01-01

    The N≈ Z nuclei in the mass A˜80 region has been researched because of an abundance of nuclear structure phenomena. The projected shell model (PSM) was adopted to investigate the structure of high spin state in proton-rich 74,76,78Kr isotopes including yrast spectra, moment of inertia, electric quadrupole transitions and the behavior of single particle. The calculated results are in good agreement with available data and the shape coexistence in low-spin is also discussed.

  1. Tidal Evolution of the Moon from a High-Obliquity Fast-Spinning Earth

    NASA Astrophysics Data System (ADS)

    Cuk, Matija; Stewart, Sarah; Lock, Simon; Hamilton, Douglas

    2015-11-01

    In the conventional Giant Impact (GI) model of lunar formation, the Moon forms primarily from the debris of the impactor that is launched into Earth orbit. This is in conflict with extremely Earth-like isotopic composition of the Moon. All pre-2012 GI models relied on the classic picture of lunar tidal evolution (e.g. Goldreich 1965, Touma and Wisdom 1994) in which angular momentum (AM) of the Earth-Moon system has been conserved since lunar formation. Cuk and Stewart (2012) showed that a high-AM Earth-Moon system can lose AM through the evection resonance between the Moon and the Sun, allowing for GIs that are more conducive to incorporating Earth material into the Moon. More recently, Lock et al. (2015) show that a very-fast spinning Earth should be heavily coupled to the protolunar disk, resulting in the uniform composition of the Moon and Earth's mantle. While the geophysical and geochemical benefits of the high-AM GI are clear, further confirmation is needed that AM loss is both likely and consistent with observed lunar orbit. Not only does the evection resonance not explain the current 5-degree lunar inclination, but Chen and Nimmo (2013) show that the conventional model of lunar spin evolution (Ward 1975) would lead to large-scale damping of lunar inclination in the past. The prospect of a past high-inclination Moon requires complete revision of lunar tidal evolution models. We use a numerical integrator that follows both the orbit and the spin of the Moon, and find that the Moon was likely in non-synchronous rotation for a prolonged period during Cassini state transition, implying inclination damping in excess of that in synchronous rotation. We propose that the Moon's composition and past large inclination can be explained by Earth's post-GI obliquity of about 70 degrees, which led to instability of lunar orbit at the Laplace plane transition (Tremaine et al. 2009), causing AM loss, Earth obliquity reduction and lunar inclination excitation. Subsequent

  2. Slow-Motion Theory of Nuclear Spin Relaxation in Paramagnetic Low-Symmetry Complexes: A Generalization to High Electron Spin

    NASA Astrophysics Data System (ADS)

    Nilsson, T.; Kowalewski, J.

    2000-10-01

    The slow-motion theory of nuclear spin relaxation in paramagnetic low-symmetry complexes is generalized to comprise arbitrary values of S. We describe the effects of rhombic symmetry in the static zero-field splitting (ZFS) and allow the principal axis system of the static ZFS tensor to deviate from the molecule-fixed frame of the nuclear-electron dipole-dipole tensor. We show nuclear magnetic relaxation dispersion (NMRD) profiles for different illustrative cases, ranging from within the Redfield limit into the slow-motion regime with respect to the electron spin dynamics. We focus on S = 3/2 and compare the effects of symmetry-breaking properties on the paramagnetic relaxation enhancement (PRE) in this case with that of S = 1, which we have treated in a previous paper. We also discuss cases of S = 2, 5/2, 3, and 7/2. One of the main objectives of this investigation, together with the previous papers, is to provide a set of standard calculations using the general slow-motion theory, against which simplified models may be tested.

  3. A hybrid-systems approach to spin squeezing using a highly dissipative ancillary system

    NASA Astrophysics Data System (ADS)

    Dooley, Shane; Yukawa, Emi; Matsuzaki, Yuichiro; Knee, George C.; Munro, William J.; Nemoto, Kae

    2016-05-01

    Squeezed states of spin systems are an important entangled resource for quantum technologies, particularly quantum metrology and sensing. Here we consider the generation of spin squeezed states by interacting the spins with a dissipative ancillary system. We show that spin squeezing can be generated in this model by two different mechanisms: one-axis twisting (OAT) and driven collective relaxation (DCR). We can interpolate between the two mechanisms by simply adjusting the detuning between the dissipative ancillary system and the spin system. Interestingly, we find that for both mechanisms, ancillary system dissipation need not be considered an imperfection in our model, but plays a positive role in spin squeezing. To assess the feasibility of spin squeezing we consider two different implementations with superconducting circuits. We conclude that it is experimentally feasible to generate a squeezed state of hundreds of spins either by OAT or by DCR.

  4. Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2 bulk crystals

    NASA Astrophysics Data System (ADS)

    Gehlmann, Mathias; Aguilera, Irene; Bihlmayer, Gustav; Młyńczak, Ewa; Eschbach, Markus; Döring, Sven; Gospodarič, Pika; Cramm, Stefan; Kardynał, Beata; Plucinski, Lukasz; Blügel, Stefan; Schneider, Claus M.

    2016-06-01

    Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS2 bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES), we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method, we find that these valence band states at the point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS2, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS2 can be accessed without thinning it down to the monolayer limit.

  5. Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2 bulk crystals.

    PubMed

    Gehlmann, Mathias; Aguilera, Irene; Bihlmayer, Gustav; Młyńczak, Ewa; Eschbach, Markus; Döring, Sven; Gospodarič, Pika; Cramm, Stefan; Kardynał, Beata; Plucinski, Lukasz; Blügel, Stefan; Schneider, Claus M

    2016-06-01

    Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS2 bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES), we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method, we find that these valence band states at the point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS2, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS2 can be accessed without thinning it down to the monolayer limit.

  6. Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2 bulk crystals

    PubMed Central

    Gehlmann, Mathias; Aguilera, Irene; Bihlmayer, Gustav; Młyńczak, Ewa; Eschbach, Markus; Döring, Sven; Gospodarič, Pika; Cramm, Stefan; Kardynał, Beata; Plucinski, Lukasz; Blügel, Stefan; Schneider, Claus M.

    2016-01-01

    Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS2 bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES), we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method, we find that these valence band states at the point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS2, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS2 can be accessed without thinning it down to the monolayer limit. PMID:27245646

  7. Thermochemical study of the processes of complexation of cobalt(II) ions with L-histidine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Gorboletova, G. G.; Metlin, A. A.

    2015-09-01

    Thermal effects of the complexation of cobalt(II) ions with L-histidine at 298.15 K and several values of the ionic strength against the background of KNO3 are determined by means of direct calorimetry. The standard thermodynamic characteristics of the reactions of complexation in the aqueous solution have been calculated.

  8. Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

    SciTech Connect

    Yoshimi, A.; Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S.

    2009-08-04

    A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical-coupling spin maser is improved by installation of a low-noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

  9. Fabrication of biomimetic high performance antireflective and antifogging film by spin-coating.

    PubMed

    Zhang, Liang; Lü, Changli; Li, Yunfeng; Lin, Zhe; Wang, Zhanhua; Dong, Heping; Wang, Tieqiang; Zhang, Xuemin; Li, Xiao; Zhang, Junhu; Yang, Bai

    2012-05-15

    In this paper, we report a facile way to fabricate biomimetic high performance optical hybrid films with excellent antireflective and antifogging properties by one-step spin-coating the mixture of mesoporous SiO(2) particles and SiO(2) sol. The production process of the films is easy, low-cost, and time-efficient. Mesoporous SiO(2) particles containing surfactants disperse in SiO(2) sol stably without any chemical modification, which decrease the effective refractive index and increase the transmittance of the films. In addition, such films possess superhydrophilic properties and exhibit high performance antifogging properties. Due to the good film forming performance of SiO(2) sol, mesoporous SiO(2) particles are embedded in the films and impart the films high mechanical stability and durability. The surface morphology of the films can maintain well after repeated friction, and the performances of antireflective and antifogging also do not change as well.

  10. Thermochromism, stability and thermodynamics of cobalt(II) complexes in newly synthesized nitrate based ionic liquid and its photostability.

    PubMed

    Banić, Nemanja; Vraneš, Milan; Abramović, Biljana; Csanádi, János; Gadžurić, Slobodan

    2014-11-07

    In this work a 1-(2-hydroxyethyl)-3-methylimidazolium nitrate ionic liquid, [HO(CH2)2mim]NO3, has been synthesized in order to serve as a new thermochromic material upon addition of cobalt(II) ions. Spectrophotometric measurements of a series of cobalt(II) nitrate and cobalt(II) chloride solutions in [HO(CH2)2mim]NO3 at 298.15, 308.15, 318.15, 328.15, and 338.15 K, were performed. Based on the recorded spectra, the overall stability constants and thermodynamic parameters for the cobalt(II) associations with chloride and nitrate ions were calculated. The thermodynamic calculations suggest that thermochromism is not observed in the ionic medium due to a small entropy change during the replacement of nitrate with chloride ions in the co-ordination sphere of cobalt(II). The absence of the molecular solvent was also the reason for the lack of thermochromism. Thus, cobalt(II) solutions in [HO(CH2)2mim]NO3 and water mixtures were studied as a new and green medium that can be used for the auto-regulation of the light intensity and shade protection. The investigated system with water upon addition of cobalt(II) was found to be a far more efficient and responsive thermochromic medium for all of the studied systems up until now. The structure of [HO(CH2)2mim]NO3 was confirmed by both (1)H NMR and IR spectroscopy. Also, the efficiency of different advanced oxidation processes (UV-induced photolysis, UV/H2O2 photolysis, heterogeneous photocatalysis using TiO2 Degussa P25 and TiO2 with 7.24%, w/w Fe catalysts) for [HO(CH2)2mim]NO3 degradation were investigated. The reaction intermediates formed during the photo-oxidation process were identified using LC-ESI-MS/MS and (1)H NMR techniques.

  11. Local structure and spin transition in Fe2O3 hematite at high pressure

    NASA Astrophysics Data System (ADS)

    Sanson, Andrea; Kantor, Innokenty; Cerantola, Valerio; Irifune, Tetsuo; Carnera, Alberto; Pascarelli, Sakura

    2016-07-01

    The pressure evolution of the local structure of Fe2O3 hematite has been determined by extended x-ray absorption fine structure up to ˜79 GPa. Below the phase-transition pressure at ˜50 GPa, no increasing of FeO6 octahedra distortion is observed as pressure is applied. Above the phase transition, an abrupt decrease of the nearest-neighbor Fe-O distance is observed concomitantly with a strong reduction in the FeO6 distortion. This information on the local structure, used as a test-bench for the different high-pressure forms proposed in the literature, suggests that the orthorhombic structure with space group A b a 2 , recently proposed by Bykova et al. [Nat. Commun. 7, 10661 (2016), 10.1038/ncomms10661], is the most probable, but puts into question the presence of the P 21 /n form in the pressure range 54-67 GPa. Finally, the crossover from Fe high-spin to low-spin states with pressure increase has been monitored from the pre-edge region of the Fe K -edge absorption spectra. Its "simultaneous" comparison with the local structural changes allows us to conclude that it is the electronic transition that drives the structural transition and not vice versa.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. High-spin lifetime measurements in the N=Z nucleus {sup 72}Kr

    SciTech Connect

    Andreoiu, C.; Svensson, C. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hyland, B.; Phillips, A. A.; Schumaker, M. A.; Valiente-Dobon, J. J.; Afanasjev, A. V.; Austin, R. A. E.; Carpenter, M. P.; Freeman, S. J.; Greene, J.; Moore, F.; Mukherjee, G.; Seweryniak, D.; Dashdorj, D.; Goergen, A.

    2007-04-15

    High-spin states in the N=Z nucleus {sup 72}Kr have been populated in the {sup 40}Ca({sup 40}Ca, 2{alpha}){sup 72}Kr fusion-evaporation reaction at a beam energy of 165 MeV using the Gammasphere array for {gamma}-ray detection coupled to the Microball array for charged particle detection. The previously observed bands in {sup 72}Kr were extended to an excitation energy of {approx}24 MeV and angular momentum of 30({Dirac_h}/2{pi}). Using the Doppler shift attenuation method the lifetimes of high-spin states were measured for the first time. Excellent agreement between the results of calculations within the isovector mean field theory and experiment is observed both for rotational and deformation properties. No enhancement of quadrupole deformation expected in the presence of isoscalar t=0 np pairing is observed. Current data do not show any evidence for the existence of the isoscalar np pairing.

  14. Average magnetic moments of pre-yrast high spin states in {sup 166,165}Hf

    SciTech Connect

    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.}

  15. Low temperature and high field regimes of connected kagome artificial spin ice: the role of domain wall topology

    PubMed Central

    Zeissler, Katharina; Chadha, Megha; Lovell, Edmund; Cohen, Lesley F.; Branford, Will R.

    2016-01-01

    Artificial spin ices are frustrated magnetic nanostructures where single domain nanobars act as macrosized spins. In connected kagome artificial spin ice arrays, reversal occurs along one-dimensional chains by propagation of ferromagnetic domain walls through Y-shaped vertices. Both the vertices and the walls are complex chiral objects with well-defined topological edge-charges. At room temperature, it is established that the topological edge-charges determine the exact switching reversal path taken. However, magnetic reversal at low temperatures has received much less attention and how these chiral objects interact at reduced temperature is unknown. In this study we use magnetic force microscopy to image the magnetic reversal process at low temperatures revealing the formation of quite remarkable high energy remanence states and a change in the dynamics of the reversal process. The implication is the breakdown of the artificial spin ice regime in these connected structures at low temperatures. PMID:27443523

  16. Low temperature and high field regimes of connected kagome artificial spin ice: the role of domain wall topology

    NASA Astrophysics Data System (ADS)

    Zeissler, Katharina; Chadha, Megha; Lovell, Edmund; Cohen, Lesley F.; Branford, Will R.

    2016-07-01

    Artificial spin ices are frustrated magnetic nanostructures where single domain nanobars act as macrosized spins. In connected kagome artificial spin ice arrays, reversal occurs along one-dimensional chains by propagation of ferromagnetic domain walls through Y-shaped vertices. Both the vertices and the walls are complex chiral objects with well-defined topological edge-charges. At room temperature, it is established that the topological edge-charges determine the exact switching reversal path taken. However, magnetic reversal at low temperatures has received much less attention and how these chiral objects interact at reduced temperature is unknown. In this study we use magnetic force microscopy to image the magnetic reversal process at low temperatures revealing the formation of quite remarkable high energy remanence states and a change in the dynamics of the reversal process. The implication is the breakdown of the artificial spin ice regime in these connected structures at low temperatures.

  17. Low temperature and high field regimes of connected kagome artificial spin ice: the role of domain wall topology.

    PubMed

    Zeissler, Katharina; Chadha, Megha; Lovell, Edmund; Cohen, Lesley F; Branford, Will R

    2016-07-22

    Artificial spin ices are frustrated magnetic nanostructures where single domain nanobars act as macrosized spins. In connected kagome artificial spin ice arrays, reversal occurs along one-dimensional chains by propagation of ferromagnetic domain walls through Y-shaped vertices. Both the vertices and the walls are complex chiral objects with well-defined topological edge-charges. At room temperature, it is established that the topological edge-charges determine the exact switching reversal path taken. However, magnetic reversal at low temperatures has received much less attention and how these chiral objects interact at reduced temperature is unknown. In this study we use magnetic force microscopy to image the magnetic reversal process at low temperatures revealing the formation of quite remarkable high energy remanence states and a change in the dynamics of the reversal process. The implication is the breakdown of the artificial spin ice regime in these connected structures at low temperatures.

  18. HDice, Highly-Polarized Low-Background Frozen-Spin HD Targets for CLAS experiments at Jefferson Lab

    SciTech Connect

    Wei, Xiangdong; Bass, Christopher; D'Angelo, Annalisa; Deur, Alexandre P.; Dezern, Gary L.; Ho, Dao Hoang; Kageya, Tsuneo; Khandaker, Mahbubul A,; Kashy, David H.; Laine, Vivien Eric; Lowry, Michael M.; O'Connell, Thomas Robert; Sandorfi, Andrew M.; Teachey, II, Robert W.; Whisnant, Charles Steven; Zarecky, Michael R.

    2012-12-01

    Large, portable frozen-spin HD (Deuterium-Hydride) targets have been developed for studying nucleon spin properties with low backgrounds. Protons and Deuterons in HD are polarized at low temperatures (~10mK) inside a vertical dilution refrigerator (Oxford Kelvinox-1000) containing a high magnetic field (up to 17T). The targets reach a frozen-spin state within a few months, after which they can be cold transferred to an In-Beam Cryostat (IBC). The IBC, a thin-walled dilution refrigerator operating either horizontally or vertically, is use with quasi-4{pi} detector systems in open geometries with minimal energy loss for exiting reaction products in nucleon structure experiments. The first application of this advanced target system has been used for Spin Sum Rule experiments at the LEGS facility in Brookhaven National Laboratory. An improved target production and handling system has been developed at Jefferson Lab for experiments with the CEBAF Large Acceptance Spectrometer, CLAS.

  19. Monomeric square-planar cobalt(II) acetylacetonate: mystery or mistake?

    PubMed

    Vreshch, Volodimir D; Yang, Jen-Hsien; Zhang, Haitao; Filatov, Alexander S; Dikarev, Evgeny V

    2010-09-20

    No evidence was found for the existence of a previously reported mononuclear square-planar form of unsolvated cobalt(II) acetylacetonate, Co(acac)(2), in all samples that have been obtained by using a variety of preparative techniques and crystallization conditions. It was confirmed that the structure of tetramer Co(4)(acac)(8), reported back in 1964 by Cotton and Elder, is correct, the synthesis is reproducible, and the bulk material corresponds to single-crystal data. Additionally, the title compound can be isolated in tetranuclear form by reducing cobalt(III) acetylacetonate with cobalt metal in solvent-free conditions or by crystallization from a hexanes solution. At the same time, from noncoordinating halogenated solvents, Co(acac)(2) crystallizes as a trinuclear core molecule, in which all Co atoms also exhibit octahedral coordination. From coordinating solvents such as ethanol, cobalt(II) acetylacetonate was found to appear in the form of its bis-adduct Co(acac)(2)(EtOH)(2). On the basis of observations made in this work and the details presented in the original paper, we suggest that the reported mononuclear structure of square-planar acetylacetonate should likely contain copper instead of cobalt.

  20. RHIC SPIN FLIPPER

    SciTech Connect

    BAI,M.; ROSER, T.

    2007-06-25

    This paper proposes a new design of spin flipper for RHIC to obtain full spin flip with the spin tune staying at half integer. The traditional technique of using an rf dipole or solenoid as spin flipper to achieve full spin flip in the presence of full Siberian snake requires one to change the snake configuration to move the spin tune away from half integer. This is not practical for an operational high energy polarized proton collider like RHIC where beam lifetime is sensitive to small betatron tune change. The design of the new spin flipper as well as numerical simulations are presented.

  1. Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

    PubMed

    AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

    2007-07-01

    Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

  2. High-field magnetization studies of spin-dimer behaviors on low-dimensional spin systems, LiCu2-xZnxO2 and FeTe3O7X (X = Cl, Br)

    NASA Astrophysics Data System (ADS)

    Her, J. L.; Hsu, H. C.; Matsuda, Y. H.; Kindo, K.; Chou, C. C.; Yang, H. D.; Berger, H.; Chou, F. C.

    2013-03-01

    High-field magnetization of two kinds of low-dimensional spin system was studied in pulsed magnets. Several anomalies were clearly observed in dm/dH curves of doped LiCu2-xZnxO2 (x = 0.07) at low temperatures (1.3 K < T < 20 K). When temperature decreases, the anomalies sharper / splits at certain critical temperatures which are related to the formation of isolated spin-dimer and spin freezing state. A field-induced spin density wave state was suggested to exist at high magnetic fields. The doping of Zn2+ ions breaks the spin-chain of Cu2+ ions, leading to the formation of isolated spin-dimers and lowering the critical field of formation of spin density state. The magnetization process measurements were preformed on another series of samples, FeTe3O7X (X = Cl, Br), which has spin-dimer, formed by Fe3+ ions, at low temperatures and magnetic fields up to 100 T. At low temperatures, the magnetization processes show four step-like structures, which have nearly equal spaces of 25 T. Both samples show similar behavior. These steps are considered to be the magnetic excitation of the antiferromagnetic spin-dimers.

  3. High spin states and isomeric decays in doubly-odd 208Fr

    NASA Astrophysics Data System (ADS)

    Kanjilal, D.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Raut, R.; Saha, S.; Bhowmik, R. K.; Gehlot, J.; Muralithar, S.; Singh, R. P.; Jnaneswari, G.; Mukherjee, G.; Mukherjee, B.

    2010-10-01

    Neutron deficient isotopes of francium ( Z=87, N˜121-123) as excited nuclei were produced in the fusion-evaporation reaction: 197Au( 16O, xn) 213 - xFr at 100 MeV. The γ rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half-lives of the E=194(2) keV isomeric transition, known from earlier observations, was measured to be T=233(18) ns. A second isomeric transition at E=383(2) keV and T=33(7) ns was also found. The measured half-lives were compared with the corresponding single particle estimates, based on the level scheme obtained from the experiment.

  4. Transient Loschmidt Echo and Orthogonality Catastrophe in highly excited Quantum Ising Spin Chains

    NASA Astrophysics Data System (ADS)

    Schiro, Marco; Lupo, Carla

    We study the response to sudden local perturbations of highly excited Quantum Ising Spin Chains. The key quantity encoding this response is the overlap between time-dependent wave functions, which we write as a transient Loschmidt echo. We compute the Echo perturbatively in the case of a weak local quench and study its asymptotics at long times, which contains crucial information about the structure of the highly excited non-equilibrium environment induced by the quench. Our results reveal that the Echo decays exponentially, rather than power law as in the low-energy Orthogonality Catastrophe, a further example of quench-induced decoherence. The emerging decoherence scale is set by the strenght of the local potential and the bulk excitation energy. In addition, the transient evolution features aging behavior at the Ising quantum critical point.

  5. Normal and superdeformed high-spin structures in {sup 161}Lu

    SciTech Connect

    Bringel, P.; Huebel, H.; Al-Khatib, A.; Buerger, A.; Nenoff, N.; Neusser-Neffgen, A.; Schoenwasser, G.; Singh, A.K.; Hagemann, G.B.; Herskind, B.; Jensen, D.R.; Sletten, G.; Bednarczyk, P.; Curien, D.; Joss, D.T.; Simpson, J.; Gangopadhyay, G.; Kroell, Th.; Lo Bianco, G.; Petrache, C.M.

    2006-05-15

    High-spin states in {sup 161}Lu were populated in the {sup 139}La({sup 28}Si, 6n) reaction and {gamma}-ray coincidences were measured with the EUROBALL spectrometer. On the basis of these data, the previously known level scheme is extended with new band structures and is partly revised. Configuration assignments are made to all bands based on comparison of experimental properties with cranked shell model calculations. A strongly populated band with parity and signature ({pi},{alpha})=(+,-1/2) is found to be yrast above spin I{approx_equal}33. This band shows characteristics resembling those of two triaxial superdeformed bands in this nucleus based on the occupation of the shape-driving i{sub 13/2} proton orbital. This structure, unique to {sup 161}Lu within the chain of even-N Lu isotopes, is discussed in terms of a quasiparticle configuration in a local triaxial minimum with a larger triaxiality and a smaller quadrupole deformation than calculated for the i{sub 13/2} proton excitation.

  6. Towards a highly efficient quantum spin-photon interface for an NV centre based quantum network

    NASA Astrophysics Data System (ADS)

    Bogdanovic, Stefan; Bonato, Cristian; van Dam, Suzanne; Reiserer, Andreas; Zwerver, Anne-Marije; Hanson, Ronald; Quantum Transport Team

    Nitrogen-vacancy (NV) centers in diamond recently emerged as promising candidates for realizing quantum information algorithms due to their remarkable versatility. The spin of these optically active defects can be entangled with their emitted photons, making them an excellent optical interface from the perspective of quantum communication.Recently, we have demonstrated the first building blocks of such networks, performing kilometer scale entanglement of two NV centers and teleportation of quantum information.(1) However, our current protocols are inefficient due to the low emission of NV center's resonant photons into the zero phonon line (ZPL).Here we present our efforts of coupling a single NV center emitter in a diamond membrane to a fiber-based Fabry-Perot microcavity with high finesse (F >104) at cryogenic temperatures. This approach allows spectral tuning of the cavity resonance to the ZPL emission of the NV center, thereby significantly enhancing the resonant photon emission via Purcell effect. Furthermore, the bulk environment of the NV centers protects their spin properties against surface proximity effects, which is of crucial importance for quantum information processing applications. (1) B.Hensen et al., Nature 526, 682 (2015)

  7. Systematical study of high-spin rotational bands in neutron-deficient Kr isotopes by the extended projected shell model

    NASA Astrophysics Data System (ADS)

    Wu, Xin-Yi; Ghorui, S. K.; Wang, Long-Jun; Kaneko, K.; Sun, Yang

    2017-01-01

    We analyze the high-spin structure of the even-even 72-80Kr isotopes using the Projected Shell Model (PSM). With the help of the Pfaffian formulas, we have vigorously extended the quasi-particle (qp) basis of the PSM code and applied in this mass region for the first time. We consider a sufficiently large multi-qp configuration space in order to describe high-spin rotational behavior. The results show that the calculation can reproduce most of the known rotational bands with positive- or negative-parity. Moreover, some side bands appearing in the near-yrast region are predicted. The main structure for each band is discussed in terms of multi-qp configurations. The variations in moment of inertia with spin are explained in terms of successive band crossings among the 2-qp, 4-qp, 6-qp, and 8-qp states. The B (E 2) transition probabilities in these bands are also calculated. To further understand the high-spin behavior of these neutron-deficient nuclei and to confirm predictions of the present work, good high-spin data, especially for B (E 2) transitions, are called for.

  8. {gamma}-ray spectroscopy of neutron-deficient {sup 110}Te. II. High-spin smooth-terminating structures

    SciTech Connect

    Paul, E. S.; Evans, A. O.; Boston, A. J.; Nolan, P. J.; Semple, A. T.; Chiara, C. J.; Fossan, D. B.; Lane, G. J.; Sears, J. M.; Starosta, K.; Devlin, M.; LaFosse, D. R.; Sarantites, D. G.; Freeman, S. J.; Leddy, M. J.; Lee, I. Y.; Macchiavelli, A. O.; Smith, J. F.; Afanasjev, A. V.; Ragnarsson, I.

    2007-09-15

    High-spin states have been populated in {sub 52}{sup 110}Te via {sup 58}Ni({sup 58}Ni,{alpha}2p{gamma}) reactions at 240 and 250 MeV. The Gammasphere {gamma}-ray spectrometer was used in conjunction with the Microball charged-particle detector. The high-spin (I>30) collective level scheme of {sup 110}Te, up to {approx}45({Dirac_h}/2{pi}), is discussed in this paper. Four new decoupled ({delta}I=2) high-spin structures have been observed for the first time, together with two strongly coupled ({delta}I=1) bands. These bands all show the characteristics of smooth band termination, and are discussed within the framework of the cranked Nilsson-Strutinsky approach.

  9. Mesoscopic superconductivity and high spin polarization coexisting at metallic point contacts on Weyl semimetal TaAs.

    PubMed

    Aggarwal, Leena; Gayen, Sirshendu; Das, Shekhar; Kumar, Ritesh; Süß, Vicky; Felser, Claudia; Shekhar, Chandra; Sheet, Goutam

    2017-01-10

    A Weyl semimetal is a topologically non-trivial phase of matter that hosts mass-less Weyl fermions, the particles that remained elusive for more than 80 years since their theoretical discovery. The Weyl semimetals exhibit unique transport properties and remarkably high surface spin polarization. Here we show that a mesoscopic superconducting phase with critical temperature Tc=7 K can be realized by forming metallic point contacts with silver (Ag) on single crystals of TaAs, while neither Ag nor TaAs are superconductors. Andreev reflection spectroscopy of such point contacts reveals a superconducting gap of 1.2 meV that coexists with a high transport spin polarization of 60% indicating a highly spin-polarized supercurrent flowing through the point contacts on TaAs. Therefore, apart from the discovery of a novel mesoscopic superconducting phase, our results also show that the point contacts on Weyl semimetals are potentially important for applications in spintronics.

  10. Mesoscopic superconductivity and high spin polarization coexisting at metallic point contacts on Weyl semimetal TaAs

    NASA Astrophysics Data System (ADS)

    Aggarwal, Leena; Gayen, Sirshendu; Das, Shekhar; Kumar, Ritesh; Süß, Vicky; Felser, Claudia; Shekhar, Chandra; Sheet, Goutam

    2017-01-01

    A Weyl semimetal is a topologically non-trivial phase of matter that hosts mass-less Weyl fermions, the particles that remained elusive for more than 80 years since their theoretical discovery. The Weyl semimetals exhibit unique transport properties and remarkably high surface spin polarization. Here we show that a mesoscopic superconducting phase with critical temperature Tc=7 K can be realized by forming metallic point contacts with silver (Ag) on single crystals of TaAs, while neither Ag nor TaAs are superconductors. Andreev reflection spectroscopy of such point contacts reveals a superconducting gap of 1.2 meV that coexists with a high transport spin polarization of 60% indicating a highly spin-polarized supercurrent flowing through the point contacts on TaAs. Therefore, apart from the discovery of a novel mesoscopic superconducting phase, our results also show that the point contacts on Weyl semimetals are potentially important for applications in spintronics.

  11. Spin-Tunnel Investigation of a 1/28-Scale Model of the NASA F-18 High Alpha Research Vehicle (HARV) with and without Vertical Tails

    NASA Technical Reports Server (NTRS)

    Fremaux, C. Michael

    1997-01-01

    An investigation was conducted in the NASA Langley 20-Foot Vertical Spin Tunnel to determine the developed spin and spin-recovery characteristics of a 1/28-scale, free-spinning model of the NASA F-18 HARV (High Alpha Research Vehicle) airplane that can configured with and without the vertical tails installed. The purpose of the test was to determine what effects, if any, the absence of vertical tails (and rudders) had on the spin and spin-recovery capabilities of the HARV. The model was ballasted to dynamically represent the full-scale airplane at an altitude of 25,000 feet. Erect and inverted spin tests with symmetric mass loadings were conducted with the free-spinning model. The model results indicate that the basic airplane with vertical tails installed (with unaugmented control system) will exhibit fast, flat erect and inverted spins from which acceptable recoveries can be made. Removing the vertical tails had little effect on the erect spin mode, but did degrade recoveries from erect spins. In contrast, inverted spins without the vertical tails were significantly more severe than those with the tails installed.

  12. A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry

    SciTech Connect

    Jozwiak, Chris M.; Graff, Jeff; Lebedev, Gennadi; Andresen, Nord; Schmid, Andreas; Fedorov, Alexei; El Gabaly, Farid; Wan, Weishi; Lanzara, Alessandra; Hussain, Zahid

    2010-04-13

    We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90 degrees bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.

  13. High-resolution three-dimensional spin- and angle-resolved photoelectron spectrometer using vacuum ultraviolet laser light

    NASA Astrophysics Data System (ADS)

    Yaji, Koichiro; Harasawa, Ayumi; Kuroda, Kenta; Toyohisa, Sogen; Nakayama, Mitsuhiro; Ishida, Yukiaki; Fukushima, Akiko; Watanabe, Shuntaro; Chen, Chuangtian; Komori, Fumio; Shin, Shik

    2016-05-01

    We describe a spin- and angle-resolved photoelectron spectroscopy (SARPES) apparatus with a vacuum-ultraviolet (VUV) laser (hν = 6.994 eV) developed at the Laser and Synchrotron Research Center at the Institute for Solid State Physics, The University of Tokyo. The spectrometer consists of a hemispherical photoelectron analyzer equipped with an electron deflector function and twin very-low-energy-electron-diffraction-type spin detectors, which allows us to analyze the spin vector of a photoelectron three-dimensionally with both high energy and angular resolutions. The combination of the high-performance spectrometer and the high-photon-flux VUV laser can achieve an energy resolution of 1.7 meV for SARPES. We demonstrate that the present laser-SARPES machine realizes a quick SARPES on the spin-split band structure of a Bi(111) film even with 7 meV energy and 0.7∘ angular resolutions along the entrance-slit direction. This laser-SARPES machine is applicable to the investigation of spin-dependent electronic states on an energy scale of a few meV.

  14. High-resolution three-dimensional spin- and angle-resolved photoelectron spectrometer using vacuum ultraviolet laser light.

    PubMed

    Yaji, Koichiro; Harasawa, Ayumi; Kuroda, Kenta; Toyohisa, Sogen; Nakayama, Mitsuhiro; Ishida, Yukiaki; Fukushima, Akiko; Watanabe, Shuntaro; Chen, Chuangtian; Komori, Fumio; Shin, Shik

    2016-05-01

    We describe a spin- and angle-resolved photoelectron spectroscopy (SARPES) apparatus with a vacuum-ultraviolet (VUV) laser (hν = 6.994 eV) developed at the Laser and Synchrotron Research Center at the Institute for Solid State Physics, The University of Tokyo. The spectrometer consists of a hemispherical photoelectron analyzer equipped with an electron deflector function and twin very-low-energy-electron-diffraction-type spin detectors, which allows us to analyze the spin vector of a photoelectron three-dimensionally with both high energy and angular resolutions. The combination of the high-performance spectrometer and the high-photon-flux VUV laser can achieve an energy resolution of 1.7 meV for SARPES. We demonstrate that the present laser-SARPES machine realizes a quick SARPES on the spin-split band structure of a Bi(111) film even with 7 meV energy and 0.7(∘) angular resolutions along the entrance-slit direction. This laser-SARPES machine is applicable to the investigation of spin-dependent electronic states on an energy scale of a few meV.

  15. Spin superfluidity and coherent spin precession

    NASA Astrophysics Data System (ADS)

    Bunkov, Yuriy M.

    2009-04-01

    The spontaneous phase coherent precession of the magnetization in superfluid 3He-B was discovered experimentally in 1984 at the Institute for Physical Problems, Moscow by Borovik-Romanov, Bunkov, Dmitriev and Mukharsky and simultaneously explained theoretically by Fomin (Institut Landau, Moscow). Its formation is a direct manifestation of spin superfluidity. The latter is the magnetic counterpart of mass superfluidity and superconductivity. It is also an example of the Bose-Einstein condensation of spin-wave excitations (magnons). The coherent spin precession opened the way for investigations of spin supercurrent magnetization transport and other related phenomena, such as spin-current Josephson effect, process of phase slippage at a critical value of spin supercurrent, spin-current vortices, non-topological solitons (analogous to Q-balls in high energy physics) etc. New measuring techniques based on coherent spin precession made the investigation of mass counterflow and mass vortices possible owing to the spin-mass interaction. New phenomena were observed: mass-spin vortices, the Goldstone mode of the mass vortex with non-axisymmetric core, superfluid density anisotropy etc. Different types of coherent spin precession were later found in superfluid 3He-A and 3He-B confined in anisotropic aerogel, in the states with counterflow and in 3He with reduced magnetization. Finally, spin superfluidity investigations developed the basis for a modern investigation of electron spin supercurrent and spintronics.

  16. Fast Low-Spin Cobalt Complex Redox Shuttles for Dye-Sensitized Solar Cells.

    PubMed

    Xie, Yuling; Hamann, Thomas W

    2013-01-17

    A low-spin cobalt(II) complex, cobalt bis(trithiacyclononane), [Co(ttcn)2](3+/2+), was investigated for use as a redox shuttle in dye-sensitized solar cells, DSSCs. This unique cobalt complex redox shuttle is stable, transparent, and easy to synthesize from commercial ligands and has attractive energetic and kinetic features for use in DSSCs. Initial results indicate that the overall performance is limited by recombination. Variation of the sensitizer and deposition of an ultrathin coating of alumina on nanoparticle-based TiO2 DSSC photoanodes reduced recombination, which resulted in significantly improved quantum yields. The photovoltaic behavior was compared to the current record efficiency cobalt tris-bipyridine, [Co(bpy)3](3+/2+), redox shuttle and produced similar results. Further use of high extinction organic sensitizers with only ∼200 mV of driving force for regeneration was examined, which produced efficiencies of over 2%; importantly, regeneration is not rate-limiting in this system, thus demonstrating the promise of using such fast redox shuttles.

  17. Static quadrupole moment of high-spin isomers in the doubly-odd {sup 214}Fr nucleus

    SciTech Connect

    Neyens, G.; Van Asbroeck, I.; Coussement, R.

    1995-06-01

    We have determined the spectroscopic quadrupole moment of two high-spin isomers ({ital I}=11 {h_bar} and {ital I}=32 {h_bar}) which have recently been identified in the doubly-odd {sup 214}Fr nucleus. The data have been extracted from a series of former level mixing spectroscopy (LEMS) measurements which had been performed to measure quadrupole moments of high-spin isomers in {sup 211,212,213}Fr isotopes. The quadrupole frequencies were measured in natural and enriched poly- and single-crystalline T1 at different temperatures.

  18. Evolution from spherical single-particle structure to stable triaxiality at high spins in {sup 140}Nd

    SciTech Connect

    Petrache, C.M.; Fantuzi, M.; LoBianco, G.; Mengoni, D.; Neusser-Neffgen, A.; Huebel, H.; Al-Khatib, A.; Bringel, P.; Buerger, A.; Nenoff, N.; Schoenwasser, G.; Singh, A.K.; Ragnarsson, I.; Hagemann, G.B.; Herskind, B.; Jensen, D.R.; Sletten, G.; Fallon, P.; Goergen, A.; Bednarczyk, P.

    2005-12-15

    The level structure of {sub 60}{sup 140}Nd{sub 80} has been established up to spin 48 by in-beam {gamma}-ray spectroscopy by use of the {sup 96}Zr({sup 48}Ca, 4n) reaction. High-fold {gamma}-ray coincidences were measured with the EUROBALL spectrometer. Twelve new rotational bands have been discovered at high spins. They are interpreted as being formed in a deep triaxial minimum at {epsilon}{sub 2}{approx_equal}0.25 and {gamma}{approx_equal}35 deg. Possible configurations are assigned to the observed bands on the basis of configuration-dependent cranked Nilsson-Strutinsky calculations.

  19. Spin-charge coupling and the high-energy magnetodielectric effect in hexagonal HoMnO3

    NASA Astrophysics Data System (ADS)

    Rai, R. C.; Cao, J.; Musfeldt, J. L.; Kim, S. B.; Cheong, S.-W.; Wei, X.

    2007-05-01

    We investigate the optical and magneto-optical properties of HoMnO3 in order to elucidate the spin-charge coupling and high-energy magnetodielectric effect. We find that the Mnd to d excitations are sensitive to the cascade of low-temperature magnetic transitions involving the Mn3+ moment, direct evidence for spin-charge coupling. An applied magnetic field also modifies the on-site excitations. The high-energy magnetodielectric contrast ( ˜8% at 20T near 1.8eV ) derives from the substantial mixing in this multiferroic system.

  20. Ringlike spin segregation of binary mixtures in a high-velocity rotating drum

    NASA Astrophysics Data System (ADS)

    Decai, Huang; Ming, Lu; Gang, Sun; Yaodong, Feng; Min, Sun; Haiping, Wu; Kaiming, Deng

    2012-03-01

    This study presents molecular dynamics simulations on the segregation of binary mixtures in a high-velocity rotating drum. Depending on the ratio between the particle radius and density, similarities to the Brazil-nut effect and its reverse form are shown in the ringlike spin segregation patterns in radial direction. The smaller and heavier particles accumulated toward the drum wall, whereas the bigger and lighter particles accumulated toward the drum center. The effects of particle radius and density on the segregation states were quantified and the phase diagram of segregation in the ρb/ρs - rb/rs space was plotted. The observed phenomena can be explained by the combined percolation and the buoyancy effects.

  1. Deformation increase of high-spin core-excited isomers in the astatine nuclei

    SciTech Connect

    Scheveneels, G.; Hardeman, F.; Neyens, G.; Coussement, R. )

    1991-06-01

    Quadrupole moments of six high-spin isomers in the At isotopes have been measured with the level-mixing-spectroscopy method: {sup 208}At(16{sup {minus}}), {sup 209}At(29/2{sup +}), {sup 210}At(19{sup +},15{sup {minus}}), {sup 211}At(39/2{sup {minus}},29/2{sup +}). The results show that level mixing spectroscopy is a promising technique to determine quadrupole moments of isomers that are difficult to measure by other in-beam hyperfine interaction methods. A large increase of the quadrupole moment is observed if neutrons are excited across or removed from the {ital N}=126 shell closure. This behavior is explained in terms of an enhanced core softness for fewer core neutrons; the aligned valence particles, moving in equatorial orbits, then easily polarize the core towards oblate deformation.

  2. High spin spectroscopy of near spherical nuclei: Role of intruder orbitals

    SciTech Connect

    Bhattacharyya, S.; Bhattacharjee, T.; Mukherjee, G.; Banerjee, D.; Das, S. K.; Guin, R.; Gupta, S. Das

    2014-08-14

    High spin states of nuclei in the vicinity of neutron shell closure N = 82 and proton shell closure Z = 82 have been studied using the Clovere Ge detectors of Indian National Gamma Array. The shape driving effects of proton and neutron unique parity intruder orbitals for the structure of nuclei around the above shell closures have been investigated using light and heavy ion beams. Lifetime measurements of excited states in {sup 139}Pr have been done using pulsed-beam-γ coincidence technique. The prompt spectroscopy of {sup 207}Rn has been extended beyond the 181μs 13/2{sup +} isomer. Neutron-rich nuclei around {sup 132}Sn have been produced from proton induced fission of {sup 235}U and lifetime measurement of low-lying states of odd-odd {sup 132}I have been performed from offline decay.

  3. GDR as a Probe of the Collective Motion in Nuclei at High Spins, Temperatures or Isospins

    SciTech Connect

    Maj, Adam

    2008-11-11

    The gamma-decay of the Giant Dipole Resonance (GDR), the high-frequency collective vibration of protons against neutrons, has been proven to be a basic probe for the shapes of hot nuclei, especially to study the effective shape evolution caused by the collective rotation of a nucleus. In this context an interesting question arises: what is the nuclear shape at extreme values of spin or temperatures, close to the limit impose by another collective motion--fission, and how evolves the giant dipole collective vibrations as a function of isospin. Short overview of the results from the experiments aimed to answer these questions are presented and possible perspectives of these type of studies for exotic nuclei to be obtained with the novel gamma-calorimeter PARIS and soon available intense radioactive beams are discussed.

  4. 3D CFD Simulation of Horizontal Spin Casting of High Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Redkin, Konstantin; Balakin, Boris; Hrizo, Christopher; Vipperman, Jeffrey; Garcia, Isaac; University Of Pittsburgh Team; Whemco Collaboration; University Of Bergen Collaboration

    2013-11-01

    The present paper reports some preliminary results on the multiphase modeling of the melt behavior in the horizontal spinning chamber. Three-dimensional (3D) computational fluid dynamics (CFD) model of the high speed steel (HSS) melt was developed in a novel way on the base of volume-of-fluid technique. Preliminary 3D CFD of the horizontal centrifugal casting process showed that local turbulences can take place depending on the geometrical features of the ``feeding'' arm (inlet), its position relative to the chamber, pouring rates and temperatures. The distribution of the melt inside the mold is directly related to the melt properties (viscosity and diffusivity), which depend on the temperature and alloy composition. The predicted liquid properties, used in the modeling, are based on actual chemical composition analysis performed on different heats. Acknowledgement of WHEMCO and United Rolls Inc. for supporting the program. Special appreciation for Kevin Marsden.

  5. High-resolution electron microscopy in spin pumping NiFe/Pt interfaces

    SciTech Connect

    Ley Domínguez, D. Sáenz-Hernández, R. J.; Faudoa Arzate, A.; Arteaga Duran, A. I.; Ornelas Gutiérrez, C. E.; Solís Canto, O.; Botello-Zubiate, M. E.; Rivera-Gómez, F. J.; Matutes-Aquino, J. A.; Azevedo, A.; Silva, G. L. da; Rezende, S. M.

    2015-05-07

    In order to understand the effect of the interface on the spin pumping and magnetic proximity effects, high resolution transmission electron microscopy and ferromagnetic resonance (FMR) were used to analyze Py/Pt bilayer and Pt/Py/Pt trilayer systems. The samples were deposited by dc magnetron sputtering at room temperature on Si (001) substrates. The Py layer thickness was fixed at 12 nm in all the samples and the Pt thickness was varied in a range of 0–23 nm. A diffusion zone of approximately 8 nm was found in the Py/Pt interfaces and confirmed by energy dispersive X-ray microanalysis. The FMR measurements show an increase in the linewidth and a shift in the ferromagnetic resonance field, which reach saturation.

  6. High-spin states and a new band based on the isomeric state in 152Nd

    NASA Astrophysics Data System (ADS)

    Yeoh, E. Y.; Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Yang, Y. C.; Sun, Y.; Hwang, J. K.; Liu, S. H.; Wang, J. G.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Ding, H. B.; Li, K.; Gu, L.; Xu, Q.; Xiao, Z. G.; Ma, W. C.

    2010-08-01

    High-spin states of the neutron-rich 152Nd nucleus have been reinvestigated by measuring the prompt γ -rays in the spontaneous fission of 252Cf . The ground-state band and a side negative-parity band have been updated. A new band based on the 2243.7keV isomeric state has been identified. The half-life for the isomeric state has been measured to be 63(7)ns. The projected shell model is employed to study the band structure of this nucleus. The results show that the calculated levels of the bands are in good agreement with the experimental ones, and the isomeric state and the negative-parity band are based on the proton π5/2-[532] ⊗ π9/2+[404] and neutron ν3/2-[521] ⊗ ν5/2+[642] two-quasiparticles configurations, respectively.

  7. Determination of the molecular structure of the short-lived light-induced high-spin state in the spin-crossover compound [Fe(6-mepy)3tren](PF6)2

    NASA Astrophysics Data System (ADS)

    Chakraborty, Pradip; Tissot, Antoine; Peterhans, Lisa; Guénée, Laure; Besnard, Céline; Pattison, Philip; Hauser, Andreas

    2013-06-01

    In the spin-crossover compound [Fe(6-mepy)3tren](PF6)2, (6-mepy)3tren = tris{4-[(6-methyl)-2-pyridyl]-3-aza-butenyl}amine, the high-spin state can be populated as a metastable state below the thermal transition temperature via irradiation into the metal to the ligand charge-transfer absorption band of the low-spin species. At 10 K, the lifetime of this metastable state is only 1 s. Despite this, it is possible to determine an accurate excited state structure by following the evolution of relevant structural parameters by synchrotron x-ray diffraction under continuous irradiation with increasing intensity. The difference in metal-ligand bond length between the high-spin and the low-spin states is found to be 0.192 Å, obtained from an analysis of the experimental data using the mean-field approximation to model cooperative effects.

  8. Ultrafast Magnetism of a Ferrimagnet across the Spin-Flop Transition in High Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Becker, J.; Tsukamoto, A.; Kirilyuk, A.; Maan, J. C.; Rasing, Th.; Christianen, P. C. M.; Kimel, A. V.

    2017-03-01

    We show that applying magnetic fields up to 30 T has a dramatic effect on the ultrafast spin dynamics in ferrimagnetic GdFeCo. Upon increasing the field beyond a critical value, the dynamics induced by a femtosecond laser excitation strongly increases in amplitude and slows down significantly. Such a change in spin response is explained by different dynamics of the Gd and FeCo magnetic sublattices following a spin-flop phase transition from a collinear to a noncollinear spin state.

  9. High-spin states and level structure in {sup 84}Rb

    SciTech Connect

    Shen Shuifa; Han Guangbing; Wen Shuxian; Gu Jianzhong; Wu Xiaoguang; Zhu Lihua; He Chuangye; Li Guangsheng; Yu Beibei; Pan Feng; Zhu Jianyu; Draayer, J. P.; Wen Tingdun; Yan, Yupeng

    2010-07-15

    High-spin states in {sup 84}Rb have been studied by using the {sup 70}Zn({sup 18}O,p3n){sup 84}Rb reaction at beam energy of 75 MeV. The gamma-gamma coincidence, excitation function, and ratios for directional correlation of oriented states were determined. A new level scheme was established in which the positive- and negative-parity bands have been extended up to 17{sup +} and 17{sup -} with an excitation energy of about 7 MeV. The signature splitting and signature inversion of the positive-parity yrast band were observed. To understand the microscopic origin of the signature inversion in the yrast positive-parity bands of doubly odd Rb nuclei, as an example, we performed calculations using the projected shell model to describe the energy spectra in {sup 84}Rb. It can be seen that the main features are reproduced in the calculations. This analysis shows that the signature splitting, especially its inversion, can be reproduced by varying only the gamma deformation with increasing spin. To research the deformation of {sup 84}Rb carefully, we calculate the total Routhian surfaces of positive-parity yrast states by the cranking shell model formalism. In addition, the results of theoretical calculations about the negative-parity yrast band in {sup 84}Rb with configuration pi(p{sub 3/2},f{sub 5/2}) x nug{sub 9/2} are compared with experimental data, and a band diagram calculated for this band is also shown to extract physics from the numerical results.

  10. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    SciTech Connect

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  11. Spin-Spin Coupling in Asteroidal Binaries

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Morbidelli, Alessandro

    2015-11-01

    Gravitationally bound binaries constitute a substantial fraction of the small body population of the solar system, and characterization of their rotational states is instrumental to understanding their formation and dynamical evolution. Unlike planets, numerous small bodies can maintain a perpetual aspheroidal shape, giving rise to a richer array of non-trivial gravitational dynamics. In this work, we explore the rotational evolution of triaxial satellites that orbit permanently deformed central objects, with specific emphasis on quadrupole-quadrupole interactions. Our analysis shows that in addition to conventional spin-orbit resonances, both prograde and retrograde spin-spin resonances naturally arise for closely orbiting, highly deformed bodies. Application of our results to the illustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10% for leading-order spin-spin resonances. Cumulatively, our results suggest that spin-spin coupling may be consequential for highly elongated, tightly orbiting binary objects.

  12. Neutron scattering studies of spin-phonon hybridization and superconducting spin gaps in the high temperature superconductor La2-x(Sr;Ba)xCuO4

    DOE PAGES

    Wagman, J. J.; Carlo, Jeremy P.; Gaudet, J.; ...

    2016-03-14

    We present time-of-flight neutron-scattering measurements on single crystals of La2-xBaxCuO4 (LBCO) with 0 ≤ x ≤ 0.095 and La2-xSrxCuO4 (LSCO) with x = 0.08 and 0.11. This range of dopings spans much of the phase diagram relevant to high temperature cuprate superconductivity, ranging from insulating, three dimensional commensurate long range antiferromagnetic order for x ≤ 0.02 to two dimensional (2D) incommensurate antiferromagnetism co-existing with superconductivity for x ≥ 0.05. Previous work on lightly doped LBCO with x = 0.035 showed a clear resonant enhancement of the inelastic scattering coincident with the low energy crossings of the highly dispersive spin excitationsmore » and quasi-2D optic phonons. The present work extends these measurements across the phase diagram and shows this enhancement to be a common feature to this family of layered quantum magnets. Furthermore we show that the low temperature, low energy magnetic spectral weight is substantially larger for samples with non-superconducting ground states relative to any of the samples with superconducting ground states. Lastly spin gaps, suppression of low energy magnetic spectral weight, are observed in both superconducting LBCO and LSCO samples, consistent with previous observations for superconducting LSCO« less

  13. Cobalt(II) Ammine Complexes as Reversible Absorbers of Oxygen.

    ERIC Educational Resources Information Center

    Saito, Kazuo; Ogino, Kazuko

    1988-01-01

    Describes experiments designed to measure the oxygen content in the atmosphere and related areas in the high school laboratories. Considers the application of these activities to other programs. Includes a description of the binuclear complex and recommended procedures. (CW)

  14. High-sensitivity single NV magnetometry by spin-to-charge state mapping

    NASA Astrophysics Data System (ADS)

    Jaskula, Jean-Christophe; Shields, Brendan; Bauch, Erik; Lukin, Mikhail; Walsworth, Ronald; Trifonov, Alexei

    2015-05-01

    Nitrogen-Vacancy (NV) centers in diamond are atom-like quantum system in a solid state matrix whom its structure allows optical readout of the electronic spin. However, the optimal duration of optical readout is limited by a singlet state lifetime making single shot spin readout out of reach. On the other side, the NV center charge state readout can be extremely efficient (up to 99% fidelity) by using excitation at 594 nm. We will present a new method of spin readout utilizing a spin-depending photoionization process to map the electronic spin state of the NV onto the its charge state. Moreover, pre-selection on the charged state allows to minimize data acquisition time. This scheme improves single NV AC magnetometry by a factor of 5 and will benefit other single NV center experiments as well.

  15. Note: High sensitivity pulsed electron spin resonance spectroscopy with induction detection.

    PubMed

    Twig, Ygal; Dikarov, Ekaterina; Hutchison, Wayne D; Blank, Aharon

    2011-07-01

    Commercial electron spin resonance spectroscopy and imaging systems make use of the so-called "induction" or "Faraday" detection, which is based on a radio frequency coil or a microwave resonator. The sensitivity of induction detection does not exceed ~3 × 10(8) spins/√Hz. Here we show that through the use of a new type of surface loop-gap microresonators (inner size of 20 μm), operating at cryogenic temperatures at a field of 0.5 T, one can improve upon this sensitivity barrier by more than 2 orders of magnitude and reach spin sensitivities of ~1.5 × 10(6) spins/√Hz or ~2.5 × 10(4) spins for 1 h.

  16. Characterization of cobalt(II) chloride-modified condensation polyimide films

    NASA Technical Reports Server (NTRS)

    Rancourt, J. D.; Taylor, L. T.

    1988-01-01

    The effect of solvent extraction on the properties of cobalt(II) chloride-modified polyimide films was investigated. Solvent-cast films were prepared from solutions of cobalt chloride in poly(amide acid)/N,N-dimethylacetamide (DMAc) and were subsequently dried and cured in static air, forced air, or inert gas ovens with controlled humidity. The films were extracted by either of the three processes (1) soaking in a tray with distilled water at room temperature, (2) soxhlett extraction with distilled water, or (3) soxhell extraction with DMAc. Extraction with DMAc was found to remove both cobalt and chlorine from the films and to slightly increase bulk thermal stability and both surface resistivity and electrical resistivity.

  17. Coordination conversion of cobalt(II) in binary aqueous-organic solvents

    SciTech Connect

    Khvostova, N.O.; Karapetyan, G.O.; Yanush, O.V.

    1985-11-01

    It has been shown that the thermochromic conversions of cobalt(II) in binary solvents are influenced by a number of factors: the nature of the solvent, the strength of the complexes of octahedral symmetry formed, the outer-sphere influence of the solvent on the complexes, the form of the anion, the solvation of the participants in the reaction, and the interaction of the components of the solvent with one another. A correlation between the strength and the spectral position of the absorption bands of the complexes of the activator has been established, and a spectroscopic criterion for selecting the solvents has been proposed. The expediency of using binary solvents to create effective thermochromic media with variable phototransmission has been substantiated.

  18. Yaw and spin effects on high intensity sound generation and on drag of training projectiles with ring cavities

    NASA Technical Reports Server (NTRS)

    Parthasarathy, S. P.; Cho, Y. I.; Kwack, E. Y.; Back, L. H.

    1986-01-01

    Projectiles containing axisymmetric ring cavities constitute aeroacoustic sources. These produce high intensity tones which are used for coding in the SAWE (Simulation of Area Weapons Effects) system. Experimental data obtained in a free jet facility are presented describing the effects of yaw, spin and geometric projectile parameters on sound pressure and drag. In general, the sound pressure decreases with increasing yaw angle whereas the drag increases. Spin tends to increase sound pressure levels because of a reduction in asymmetry of flow. Drag increases at zero yaw approximately as the 1.5 power of sound wavelength. A significant part of the drag increase appears to be due to energy loss by sound radiation.

  19. IceCube constraints on fast-spinning pulsars as high-energy neutrino sources

    SciTech Connect

    Fang, Ke; Kotera, Kumiko; Murase, Kohta; Olinto, Angela V. E-mail: kotera@iap.fr E-mail: olinto@kicp.uchicago.edu

    2016-04-01

    Relativistic winds of fast-spinning pulsars have been proposed as a potential site for cosmic-ray acceleration from very high energies (VHE) to ultrahigh energies (UHE). We re-examine conditions for high-energy neutrino production, considering the interaction of accelerated particles with baryons of the expanding supernova ejecta and the radiation fields in the wind nebula. We make use of the current IceCube sensitivity in diffusive high-energy neutrino background, in order to constrain the parameter space of the most extreme neutron stars as sources of VHE and UHE cosmic rays. We demonstrate that the current non-observation of 10{sup 18} eV neutrinos put stringent constraints on the pulsar scenario. For a given model, birthrates, ejecta mass and acceleration efficiency of the magnetar sources can be constrained. When we assume a proton cosmic ray composition and spherical supernovae ejecta, we find that the IceCube limits almost exclude their significant contribution to the observed UHE cosmic-ray flux. Furthermore, we consider scenarios where a fraction of cosmic rays can escape from jet-like structures piercing the ejecta, without significant interactions. Such scenarios would enable the production of UHE cosmic rays and help remove the tension between their EeV neutrino production and the observational data.

  20. IceCube constraints on fast-spinning pulsars as high-energy neutrino sources

    NASA Astrophysics Data System (ADS)

    Fang, Ke; Kotera, Kumiko; Murase, Kohta; Olinto, Angela V.

    2016-04-01

    Relativistic winds of fast-spinning pulsars have been proposed as a potential site for cosmic-ray acceleration from very high energies (VHE) to ultrahigh energies (UHE). We re-examine conditions for high-energy neutrino production, considering the interaction of accelerated particles with baryons of the expanding supernova ejecta and the radiation fields in the wind nebula. We make use of the current IceCube sensitivity in diffusive high-energy neutrino background, in order to constrain the parameter space of the most extreme neutron stars as sources of VHE and UHE cosmic rays. We demonstrate that the current non-observation of 1018 eV neutrinos put stringent constraints on the pulsar scenario. For a given model, birthrates, ejecta mass and acceleration efficiency of the magnetar sources can be constrained. When we assume a proton cosmic ray composition and spherical supernovae ejecta, we find that the IceCube limits almost exclude their significant contribution to the observed UHE cosmic-ray flux. Furthermore, we consider scenarios where a fraction of cosmic rays can escape from jet-like structures piercing the ejecta, without significant interactions. Such scenarios would enable the production of UHE cosmic rays and help remove the tension between their EeV neutrino production and the observational data.

  1. High-spin configuration of Mn in Bi2Se3 three-dimensional topological insulator

    NASA Astrophysics Data System (ADS)

    Wolos, Agnieszka; Drabinska, Aneta; Borysiuk, Jolanta; Sobczak, Kamil; Kaminska, Maria; Hruban, Andrzej; Strzelecka, Stanislawa G.; Materna, Andrzej; Piersa, Miroslaw; Romaniec, Magdalena; Diduszko, Ryszard

    2016-12-01

    Electron paramagnetic resonance was used to investigate Mn impurity in Bi2Se3 topological insulator grown by the vertical Bridgman method. Mn in high-spin S=5/2, Mn2+, configuration was detected regardless of the conductivity type of the host material. This means that Mn2+(d5) energy level is located within the valence band, and Mn1+(d6) energy level is outside the energy gap of Bi2Se3. The electron paramagnetic resonance spectrum of Mn2+ in Bi2Se3 is characterized by the isotropic g-factor |g|=1.91 and large axial parameter D=-4.20 GHz h. This corresponds to the zero-field splitting of the Kramers doublets equal to 8.4 GHz h and 16.8 GHz h, respectively, which is comparable to the Zeeman splitting for the X-band. Mn in Bi2Se3 acts as an acceptor, effectively reducing native-high electron concentration, compensating selenium vacancies, and resulting in p-type conductivity. However, Mn-doping simultaneously favors formation of native donor defects, most probably selenium vacancies. For high Mn-doping it may lead to the resultant n-type conductivity related with strong non-stoichiometry and degradation of the crystal structure - switching from Bi2Se3 to BiSe phase.

  2. Ultrafast high harmonics for probing the fastest spin and charge dynamics in magnetic materials

    NASA Astrophysics Data System (ADS)

    Grychtol, Patrick

    2015-03-01

    Ultrafast light based on the high-harmonic up-conversion of femtosecond laser pulses have been successfully employed to access resonantly enhanced magnetic contrast at the Mabsorption edges of the 3d ferromagnets Fe, Co and Ni in a table-top setup. Thus, it has been possible to study element-specific dynamics in magnetic materials at femtosecond time scales in a laboratory environment, providing a wealth of opportunities for a greater fundamental understanding of correlated phenomena in solid-state matter. However, these investigations have so far been limited to linear polarized harmonics, since most techniques by which circular soft x-rays can be generated are highly inefficient reducing the photon flux to a level unfit for scientific applications. Besides presenting key findings of our ultrafast studies on charge and spin dynamics, we introduce a simple setup which allows for the efficient generation of circular harmonics bright enough for XMCD experiments. Our work thus represents a critical advance that enables element-specific imaging and spectroscopy of multiple elements simultaneously in magnetic and other chiral media with very high spatial and temporal resolution on the tabletop. In collboration with Ronny Knut, Emrah Turgut, Dmitriy Zusin, Christian Gentry, Henry Kapteyn, Margaret Murnane, JILA, University of Colorado, Boulder; Justin Shaw, Hans Nembach, Tom Silva, Electromagnetics Division, NIST, Boulder, CO; and Ofer Kfir, Avner Fleischer, Oren Cohen, Extreme Nonlinear Optics Group, Solid State Institute, Technion, Israel.

  3. High-Fidelity and Ultrafast Initialization of a Hole Spin Bound to a Te Isoelectronic Center in ZnSe

    NASA Astrophysics Data System (ADS)

    St-Jean, P.; Éthier-Majcher, G.; André, R.; Francoeur, S.

    2016-10-01

    We demonstrate the optical initialization of a hole-spin qubit bound to an isoelectronic center (IC) formed by a pair of Te impurities in ZnSe, an impurity-host system providing high optical homogeneity, large electric dipole moments, and potentially advantageous coherence times. The initialization scheme is based on the spin-preserving tunneling of a resonantly excited donor-bound exciton to a positively charged Te IC, thus forming a positive trion. The radiative decay of the trion within less than 50 ps leaves a heavy hole in a well-defined polarization-controlled spin state. The initialization fidelity exceeds 98.5% for an initialization time of less than 150 ps.

  4. Highly polarized emission from electrical spin injection into an InGaAs quantum well with free carriers

    SciTech Connect

    Li, C. H.; Jonker, B. T.; Kioseoglou, G.; Petrou, A.; Korkusinski, M.; Hawrylak, P.

    2013-11-18

    We report on a highly polarized emission from InGaAs/GaAs-quantum well light-emitting diodes in which we inject spin-polarized electrons from an Fe/Schottky contact. The emission spectra consist of the e{sub 1}h{sub 1} free exciton (FX) and a feature 12 meV below FX attributed to band-to-band (BB) recombination. The FX exhibits a maximum circular polarization of 22%, with a magnetic-field dependence characteristic of spin injection from Fe. The BB emission on the other hand exhibits a polarization that is strongly bias and temperature dependent, with intriguing magnetic-field dependence: The polarization exhibits a maximum of 78% at 2.5 T and 2 K, then decreases linearly with field and reaches −78% at 7 T, attributed to magnetic-field dependent spin relaxation in the presence of excess electrons.

  5. High-Precision Calibration of Electron Beam Energy from the Hefei Light Source Using Spin Resonant Depolarization

    NASA Astrophysics Data System (ADS)

    Lan, Jie-Qin; Xu, Hong-Liang

    2014-12-01

    The electron beam energy at the Hefei Light Source (HLS) in the National Synchrotron Radiation Laboratory is highly precisely calibrated by using the method of spin resonant depolarization for the first time. The spin tune and the beam energy are determined by sweeping the frequency of a radial rf stripline oscillating magnetic field to artificially excite a spin resonance and depolarize the beam. The resonance signal is recognized by observing the sudden change of the Touschek loss counting rate of the beam. The possible systematic errors of the experiment are presented and the accuracy of the calibrated energy is shown to be about 10-4. A series of measurements show that the energy stability of the machine is of the order of 9 × 10-3.

  6. High-efficiency control of spin-wave propagation in ultra-thin yttrium iron garnet by the spin-orbit torque

    NASA Astrophysics Data System (ADS)

    Evelt, M.; Demidov, V. E.; Bessonov, V.; Demokritov, S. O.; Prieto, J. L.; Muñoz, M.; Ben Youssef, J.; Naletov, V. V.; de Loubens, G.; Klein, O.; Collet, M.; Garcia-Hernandez, K.; Bortolotti, P.; Cros, V.; Anane, A.

    2016-04-01

    We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by the nonlinear scattering of the coherent spin waves from current-induced excitations.

  7. Optical cooling and trapping of highly magnetic atoms: the benefits of a spontaneous spin polarization

    NASA Astrophysics Data System (ADS)

    Dreon, Davide; Sidorenkov, Leonid A.; Bouazza, Chayma; Maineult, Wilfried; Dalibard, Jean; Nascimbene, Sylvain

    2017-03-01

    From the study of long-range-interacting systems to the simulation of gauge fields, open-shell lanthanide atoms with their large magnetic moment and narrow optical transitions open novel directions in the field of ultracold quantum gases. As for other atomic species, the magneto-optical trap (MOT) is the working horse of experiments but its operation is challenging, due to the large electronic spin of the atoms. Here we present an experimental study of narrow-line dysprosium MOTs. We show that the combination of radiation pressure and gravitational forces leads to a spontaneous polarization of the electronic spin. The spin composition is measured using a Stern–Gerlach separation of spin levels, revealing that the gas becomes almost fully spin-polarized for large laser frequency detunings. In this regime, we reach the optimal operation of the MOT, with samples of typically 3× {10}8 atoms at a temperature of 15 μK. The spin polarization reduces the complexity of the radiative cooling description, which allows for a simple model accounting for our measurements. We also measure the rate of density-dependent atom losses, finding good agreement with a model based on light-induced Van der Waals forces. A minimal two-body loss rate β ∼ 2× {10}-11 cm3 s–1 is reached in the spin-polarized regime. Our results constitute a benchmark for the experimental study of ultracold gases of magnetic lanthanide atoms.

  8. Limiting values of the one-bond Csbnd H spin-spin coupling constants of the imidazole ring of histidine at high-pH

    NASA Astrophysics Data System (ADS)

    Vila, Jorge A.; Scheraga, Harold A.

    2017-04-01

    Assessment of the relative amounts of the forms of the imidazole ring of Histidine (His), namely the protonated (H+) and the tautomeric Nε2-H and Nδ1-H forms, respectively, is a challenging task in NMR spectroscopy. Indeed, their determination by direct observation of the 15N and 13C chemical shifts or the one-bond Csbnd H, 1JCH, Spin-Spin Coupling Constants (SSCC) requires knowledge of the "canonical" limiting values of these forms in which each one is present to the extent of 100%. In particular, at high-pH, an accurate determination of these "canonical" limiting values, at which the tautomeric forms of His coexist, is an elusive problem in NMR spectroscopy. Among different NMR-based approaches to treat this problem, we focus here on the computation, at the DFT level of theory, of the high-pH limiting value for the 1JCH SSCC of the imidazole ring of His. Solvent effects were considered by using the polarizable continuum model approach. The results of this computation suggest, first, that the value of 1JCε1H = 205 ± 1.0 Hz should be adopted as the canonical high-pH limiting value for this SSCC; second, the variation of 1JCε1H SSCC during tautomeric changes is minor, i.e., within ±1 Hz; and, finally, the value of 1JCδ2H SSCC upon tautomeric changes is large (15 Hz) indicating that, at high-pH or for non-protonated His at any pH, the tautomeric fractions of the imidazole ring of His can be predicted accurately as a function of the observed value of 1JCδ2H SSCC.

  9. High-spin states with seniority v=4, 5, and 6 in 119-126Sn

    NASA Astrophysics Data System (ADS)

    Astier, A.; Porquet, M.-G.; Theisen, Ch.; Verney, D.; Deloncle, I.; Houry, M.; Lucas, R.; Azaiez, F.; Barreau, G.; Curien, D.; Dorvaux, O.; Duchêne, G.; Gall, B. J. P.; Redon, N.; Rousseau, M.; Stézowski, O.

    2012-05-01

    The 119-126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C+238U at a bombarding energy of 90 MeV and 18O+208Pb at 85 MeV. Their level schemes have been built from γ rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- and odd-A 120-126Sn nuclei have been identified. Moreover, isomeric states lying around 4.5 MeV have been established in 120,122,124,126Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. The states located above 3 MeV excitation energy are ascribed to several broken pairs of neutrons occupying the νh11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e., for midoccupation and the breaking of the three neutron pairs, has been identified. This process is observed for the first time in spherical nuclei.

  10. Evaluating spin-on carbon materials at low temperatures for high wiggling resistance

    NASA Astrophysics Data System (ADS)

    Weigand, Michael; Krishnamurthy, Vandana; Wang, Yubao; Lin, Qin; Guerrero, Douglas; Simmons, Sean; Carr, Brandy

    2013-03-01

    Spin-on carbon (SOC) materials play an important role in the multilayer lithography scheme for the mass production of advanced semiconductor devices. One of the SOC's key roles in the multilayer process (photoresist, silicon-containing hardmask, SOC) is the reactive ion etch (RIE) for pattern transfer into the substrate. As aspect ratios of the SOC material increase and feature sizes decrease, the pattern transfer from SOC to substrate by a fluorine-containing RIE induces severe pattern deformation ("wiggling"), which ultimately prevents successful pattern transfer into the substrate. One process that reduces line wiggling is a high-temperature (>250°C) post-application bake of the SOC material. In this study, we developed a process for evaluating SOC materials with respect to their pattern transfer performance. This process allowed us to evaluate line-wiggling behavior with several SOC materials at lower bake temperatures. This paper will discuss novel materials design in relation to high-aspect-ratio SOC layers and wiggling resistance.

  11. Electron spin resonance spectroscopy of high purity crystals at millikelvin temperatures

    NASA Astrophysics Data System (ADS)

    Farr, Warrick G.; Creedon, Daniel L.; Goryachev, Maxim; Benmessai, Karim; Tobar, Michael E.

    2013-12-01

    Progress in the emerging field of engineered quantum systems requires the development of devices that can act as quantum memories. The realisation of such devices by doping solid state cavities with paramagnetic ions imposes a trade-off between ion concentration and cavity coherence time. Here, we investigate an alternative approach involving interactions between photons and naturally occurring impurity ions in ultra-pure crystalline microwave cavities exhibiting exceptionally high quality factors. We implement a hybrid Whispering Gallery/Electron Spin Resonance method to perform rigorous spectroscopy of an undoped single-crystal sapphire resonator over the frequency range 8{19 GHz, and at external applied DC magnetic fields up to 0.9 T. Measurements of a high purity sapphire cooled close to 100 mK reveal the presence of Fe3+, Cr3+, and V2+ impurities. A host of electron transitions are measured and identified, including the two-photon classically forbidden quadrupole transition (Δms = 2) for Fe3+, as well as hyperfine transitions of V2+.

  12. High spin-dependent tunneling magnetoresistance in magnetite powders made by arc-discharge

    NASA Astrophysics Data System (ADS)

    Prakash, T.; Williams, G. V. M.; Kennedy, J.; Rubanov, S.

    2016-09-01

    We report the successful synthesis of ferrimagnetic magnetite powders made using an arc-discharge method in a partial oxygen atmosphere. X-ray and electron diffraction measurements show that the powders also contain some antiferromagnetic hematite and a small amount of FeO and Fe that has not oxidized. The Raman data show that there is a small fraction of ferrimagnetic maghemite that cannot be seen in the x-ray diffraction data. There is a wide particle size distribution where there are nanoparticles as small as 7 nm, larger faceted nanoparticles, and particles that are up to 25 μm in diameter. The saturation magnetization at high magnetic fields is ˜74% of that found in the bulk magnetite, where the lower value is due to the presence of some antiferromagnetic hematite. The temperature dependence of the saturation magnetization changes at the Verwey transition temperature, and it has a power low dependence with an exponent of 3/2 at low temperatures and 2.23 at high temperatures above the Verwey transition temperature. Electronic transport measurements were made on a cold-pressed pellet and the electrical resistance had an exponential dependence on temperature that may be due to electrostatic charging during tunneling between small nanoparticles. A large magnetoresistance from spin-dependent tunneling between the magnetite particles was observed that reached -9.5% at 120 K and 8 T.

  13. Spin foams without spins

    NASA Astrophysics Data System (ADS)

    Hnybida, Jeff

    2016-10-01

    We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. In doing so the sums over spins have been carried out. The boundary data of each n-valent node is explicitly reduced with respect to the local gauge invariance and has a manifest geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.

  14. Highly efficient spin polarizer based on individual heterometallic cubane single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Dong, Damin

    2015-09-01

    The spin-polarized transport across a single-molecule magnet [Mn3Zn(hmp)3O(N3)3(C3H5O2)3].2CHCl3 has been investigated using a density functional theory combined with Keldysh non-equilibrium Green's function formalism. It is shown that this single-molecule magnet has perfect spin filter behaviour. By adsorbing Ni3 cluster onto non-magnetic Au electrode, a large magnetoresistance exceeding 172% is found displaying molecular spin valve feature. Due to the tunneling via discrete quantum-mechanical states, the I-V curve has a stepwise character and negative differential resistance behaviour.

  15. Modified High Frequency Radial Spin Wave Mode Spectrum in a Chirality-Controlled Nanopillar

    NASA Astrophysics Data System (ADS)

    Kolthammer, J. E.; Rudge, J.; Choi, B. C.; Hong, Y. K.

    2016-09-01

    Circular magnetic spin valve nanopillars in a dual vortex configuration have dynamic characteristics strongly dependent on the interlayer dipole coupling. We report here on frequency domain properties of such nanopillars obtained by micromagnetic simulations. After the free layer is chirality switched with spin transfer torque, a radial spin wave eigenmode spectrum forms in the free layer with unusually large edge amplitude. The structure of these modes indicate a departure from the magnetostatic processes typically observed experimentally and treated analytically in low aspect ratio isolated disks. Our findings give new details of dynamic chirality control and relxation in nanopillars and raise potential signatures for experiments.

  16. Thermal low spin-high spin equilibrium of Fe(II) in thiospinels CuFe{sub 0.5}(Sn{sub (1-x)}Ti{sub x}){sub 1.5}S{sub 4} (0{<=}x{<=}1)

    SciTech Connect

    Womes, M.; Reibel, C.; Mari, A.; Zitoun, D.

    2011-04-15

    A series of spinel compounds with composition CuFe{sub 0.5}(Sn{sub (1-x)}Ti{sub x}){sub 1.5}S{sub 4} (0{<=}x{<=}1) is analysed by X-ray diffraction, measurements of magnetic susceptibilities and {sup 57}Fe Moessbauer spectroscopy. All samples show a temperature-dependent equilibrium between an electronic low spin 3d(t{sub 2g}){sup 6}(e{sub g}){sup 0} and a high spin 3d(t{sub 2g}){sup 4}(e{sub g}){sup 2} state of the Fe(II) ions. The spin crossover is of the continuous type and extends over several hundred degrees in all samples. The Sn/Ti ratio influences the thermal equilibrium between the two spin states. Substitution of Sn(IV) by the smaller Ti(IV) ions leads to a more compact crystal lattice, which, in contrast to many metal-organic Fe(II) complexes, does not stabilise the low spin state, but increases the residual high spin fraction for T{yields}0 K. The role played by antiferromagnetic spin coupling in the stabilisation of the high spin state is discussed. The results are compared with model calculations treating the effect of magnetic interactions on spin state equilibria. -- Graphical Abstract: Comparison of fractions of high spin Fe(II) from Moessbauer spectra (circles) with plots of {chi}{sub m}T (dots) versus T. Discrepancies between both methods indicate anti-ferromagnetic spin coupling. Display Omitted Research highlights: {yields} Many Fe(II) complexes show thermally induced high spin-low spin crossover. {yields} Spin crossover in spinel compounds is extremely scarce. {yields} Usually, lattice contraction favours the low spin state in Fe(II) complexes. {yields} In these spinels, lattice contraction favours the high spin state. {yields} The stabilisation of the high spin state is explained by spin-spin interactions.

  17. Biosorption of cobalt(II) with sunflower biomass from aqueous solutions in a fixed bed column and neural networks modelling.

    PubMed

    Oguz, Ensar; Ersoy, Muhammed

    2014-01-01

    The effects of inlet cobalt(II) concentration (20-60 ppm), feed flow rate (8-19 ml/min) and bed height (5-15 cm), initial solution pH (3-5) and particle size (0.25cobalt(II) concentration, 5 cm bed height and 8 ml/min flow rate, pH 6.5 and 0.25cobalt(II) in fixed bed columns.

  18. The spin-half XXZ antiferromagnet on the square lattice revisited: A high-order coupled cluster treatment

    NASA Astrophysics Data System (ADS)

    Bishop, R. F.; Li, P. H. Y.; Zinke, R.; Darradi, R.; Richter, J.; Farnell, D. J. J.; Schulenburg, J.

    2017-04-01

    We use the coupled cluster method (CCM) to study the ground-state properties and lowest-lying triplet excited state of the spin-half XXZ antiferromagnet on the square lattice. The CCM is applied to it to high orders of approximation by using an efficient computer code that has been written by us and which has been implemented to run on massively parallelized computer platforms. We are able therefore to present precise data for the basic quantities of this model over a wide range of values for the anisotropy parameter Δ in the range - 1 ≤ Δ < ∞ of interest, including both the easy-plane (- 1 < Δ < 1) and easy-axis (Δ > 1) regimes, where Δ → ∞ represents the Ising limit. We present results for the ground-state energy, the sublattice magnetization, the zero-field transverse magnetic susceptibility, the spin stiffness, and the triplet spin gap. Our results provide a useful yardstick against which other approximate methods and/or experimental studies of relevant antiferromagnetic square-lattice compounds may now compare their own results. We also focus particular attention on the behaviour of these parameters for the easy-axis system in the vicinity of the isotropic Heisenberg point (Δ = 1) , where the model undergoes a phase transition from a gapped state (for Δ > 1) to a gapless state (for Δ ≤ 1), and compare our results there with those from spin-wave theory (SWT). Interestingly, the nature of the criticality at Δ = 1 for the present model with spins of spin quantum number s =1/2 that is revealed by our CCM results seems to differ qualitatively from that predicted by SWT, which becomes exact only for its near-classical large-s counterpart.

  19. High power all-metal spin torque oscillator using full Heusler Co{sub 2}(Fe,Mn)Si

    SciTech Connect

    Seki, Takeshi Sakuraba, Yuya; Ueda, Masaki; Okura, Ryo; Takanashi, Koki; Arai, Hiroko; Imamura, Hiroshi

    2014-09-01

    We showed the high rf power (P{sub out}) emission from an all-metal spin torque oscillator (STO) with a Co{sub 2}Fe{sub 0.4}Mn{sub 0.6}Si (CFMS)/Ag/CFMS giant magnetoresistance (GMR) stack, which was attributable to the large GMR effect thanks to the highly spin-polarized CFMS. The oscillation spectra were measured by varying the magnetic field direction, and the perpendicular magnetic field was effective to increase P{sub out} and the Q factor. We simultaneously achieved a high output efficiency of 0.013%, a high Q of 1124, and large frequency tunability. CFMS-based all-metal STO is promising for overcoming the difficulties that conventional STOs are confronted with.

  20. High-spin states in the five-valence-particle nucleus {sup 213}Po

    SciTech Connect

    Astier, Alain; Porquet, Marie-Genevieve

    2011-03-15

    Excited states in {sup 213}Po have been populated using the {sup 18}O+ {sup 208}Pb reaction at 85 MeV beam energy and studied with the Euroball IV {gamma} multidetector array. The level scheme has been built up to {approx}2.0 MeV excitation energy and spin I{approx}25/2({h_bar}/2{pi}) from the triple {gamma} coincidence data. Spin and parity values of several yrast states have been assigned from the {gamma} angular properties. The configurations of the yrast states are discussed using results of empirical shell-model calculations and by analogy with the neighboring nuclei. The spin and parity values of several low-spin states of {sup 213}Po previously identified from the {beta} decay of {sup 213}Bi are revised.

  1. Atomic Scale Investigation of a Graphene Nano-ribbon Based High Efficiency Spin Valve

    PubMed Central

    Sun, Qing-Qing; Wang, Lu-Hao; Yang, Wen; Zhou, Peng; Wang, Peng-Fei; Ding, Shi-Jin; Zhang, David Wei

    2013-01-01

    Graphene nanoribbons based electronic devices present many interesting physical properties. We designed and investigated the spin-dependent electron transport of a device configuration, which is easy to be fabricated, with an oxygen-terminated ZGNR central scatter region between two hydrogen-terminated ZGNR electrodes. According to the analysis based on non-equilibrium Green's function and density functional theory, the proposed device could maintain its good spin-filter performance (80% to 99%) and have a stable magneto resistance value up to 105%. The spin dependent electron transmission spectrum and space-resolve density of states are employed to investigate the physical origin of the spin-polarized current and magneto resistance. PMID:24132194

  2. Electrical spin injection and detection in high mobility 2DEG systems

    NASA Astrophysics Data System (ADS)

    Ciorga, M.

    2016-11-01

    In this review paper we present the current status of research related to the topic of electrical spin injection and detection in two-dimensional electron gas (2DEG) systems, formed typically at the interface between two III-V semiconductor compounds. We discuss both theoretical aspects of spin injection in case of ballistic transport as well as give an overview of available reports on spin injection experiments performed on 2DEG structures. In the experimental part we focus particularly on our recent work on all-semiconductor structures with a 2DEG confined at an inverted GaAs/(Al,Ga)As interface and with a ferromagnetic semiconductor (Ga,Mn)As employed as a source of spin-polarized electrons.

  3. The Quest for Spinning Glue in High-Energy Polarized Proton-Proton Collisions at RHIC

    SciTech Connect

    Surrow, Bernd

    2007-10-26

    The STAR experiment at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is carrying out a spin physics program colliding transverse or longitudinal polarized proton beams at {radical}(s) = 200-500 GeV to gain a deeper insight into the spin structure and dynamics of the proton. These studies provide fundamental tests of Quantum Chromodynamics (QCD).One of the main objectives of the STAR spin physics program is the determination of the polarized gluon distribution function through a measurement of the longitudinal double-spin asymmetry, A{sub LL}, for various processes. Recent results will be shown on the measurement of A{sub LL} for inclusive jet production, neutral pion production and charged pion production at {radical}(s) = 200 GeV.

  4. High-performance triisopropylsilylethynyl pentacene transistors via spin coating with a crystallization-assisting layer.

    PubMed

    Choi, Danbi; Ahn, Byungcheol; Kim, Se Hyun; Hong, Kipyo; Ree, Moonhor; Park, Chan Eon

    2012-01-01

    The effects of spin speed and an amorphous fluoropolymer (CYTOP)-patterned substrate on the crystalline structures and device performance of triisopropylsilylethynyl pentacene (TIPS-PEN) organic field-effect transistors (OFETs) were investigated. The crystallinity of the TIPS-PEN film was enhanced by decreasing the spin speed, because slow evaporation of the solvent provided a sufficient time for the formation of thermodynamically stable crystalline structures. In addition, the adoption of a CYTOP-patterned substrate induced the three-dimensional (3D) growth of the TIPS-PEN crystals, because the patterned substrate confined the TIPS-PEN molecules and allowed sufficient time for the self-organization of TIPS-PEN. TIPS-PEN OFETs fabricated at a spin speed of 300 rpm with a CYTOP-patterned substrate showed a field-effect mobility of 0.131 cm(2) V(-1) s(-1), which is a remarkable improvement over previous spin-coated TIPS-PEN OFETs.

  5. Temperature dependence of the spin relaxation in highly degenerate ZnO thin films

    SciTech Connect

    Prestgard, M. C.; Siegel, G.; Tiwari, A.; Roundy, R.; Raikh, M.

    2015-02-28

    Zinc oxide is considered a potential candidate for fabricating next-generation transparent spintronic devices. However, before this can be achieved, a thorough scientific understanding of the various spin transport and relaxation processes undergone in this material is essential. In the present paper, we are reporting our investigations into these processes via temperature dependent Hanle experiments. ZnO thin films were deposited on c-axis sapphire substrates using a pulsed laser deposition technique. Careful structural, optical, and electrical characterizations of the films were performed. Temperature dependent non-local Hanle measurements were carried out using an all-electrical scheme for spin injection and detection over the temperature range of 20–300 K. From the Hanle data, spin relaxation time in the films was determined at different temperatures. A detailed analysis of the data showed that the temperature dependence of spin relaxation time follows the linear-in-momentum Dyakonov-Perel mechanism.

  6. Spin-Torque Influence on the High-Frequency Magnetization Fluctuations in Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Petit, S.; Baraduc, C.; Thirion, C.; Ebels, U.; Liu, Y.; Li, M.; Wang, P.; Dieny, B.

    2007-02-01

    Voltage noise measurements were performed in the 3 7 GHz frequency range on magnetic tunnel junctions biased with a dc current. Magnetic noise associated with ferromagnetic resonance excitations is either amplified or reduced depending on the direction of the bias current. This effect is interpreted as the influence of spin transfer torque on the magnetization fluctuations and described using Gilbert dynamics equation including spin transfer torque and effective field terms.

  7. Unveiling self-assembled monolayers' potential for molecular spintronics: spin transport at high voltage.

    PubMed

    Galbiati, Marta; Barraud, Clément; Tatay, Sergio; Bouzehouane, Karim; Deranlot, Cyrile; Jacquet, Eric; Fert, Albert; Seneor, Pierre; Mattana, Richard; Petroff, Frédéric

    2012-12-18

    Molecular magnetic tunnel junctions using self-assembled monolayers (SAMs) as tunnel barriers show stable and efficient spin transport properties. Large tunnel magnetoresistance with a flat bias voltage dependence of the magnetoresistance is observed in La(2/3) Sr(1/3) MnO(3) /dodecylphosphonic acid SAM/Co nanocontacts. This opens the door to spintronic tailoring though SAM engineering and could also lead to new venues for spin injection in organic devices.

  8. W-band EPR studies of high-spin nitrenes with large spin-orbit contribution to zero-field splitting

    SciTech Connect

    Akimov, Alexander; Masitov, Artem; Korchagin, Denis; Chapyshev, Sergei; Misochko, Eugenii; Savitsky, Anton

    2015-08-28

    First W-band 94 GHz EPR spectra of randomly oriented triplet, quintet, and septet nitrenes formed during the photolysis of 1,3,5-triazido-2,4,6-tribromobenzene in cryogenic matrices are reported. In comparison with conventional X-band 9 GHz electron paramagnetic resonance (EPR) spectroscopy, W-band EPR spectroscopy allows the detection and complete spectroscopic characterization of all paramagnetic species formed at different stages of the photolysis of aromatic polyazides. This type of spectroscopy is of paramount importance for experimental determination of the sign of the zero-field splitting (ZFS) parameters of high-spin molecules with large spin-orbit contribution to the ZFS, caused by the effect of heavy atoms. The study shows that triplet 1,3-diazido-2,4,6-tribromo-5-nitrenobenzene (T1) has D{sub T} = 1.369 cm{sup −1}, E{sub T} = 0.093 cm{sup −1}, and g = 2.0033, quintet 1-azido-2,4,6-tribromo-3,5-dinitrenobenzene (Q1) shows D{sub Q} = − 0.306 cm{sup −1}, E{sub Q} = 0.0137 cm{sup −1}, and g = 2.0070, and septet 2,4,6-tribromo-1,3,5-trinitrenobenzene (S1) has D{sub S} = − 0.203 cm{sup −1}, E{sub S} = 0, and g = 2.0073. The experimental ZFS parameters agree well with the results of density functional theory calculations at the PBE/Ahlrichs-DZ level of theory, showing that such calculations adequately describe the magnetic properties of bromine-containing high-spin nitrenes. Both experimental and theoretical data indicate that, in contrast to all known to date quintet dinitrenes, dinitrene Q1 has the negative sign of magnetic anisotropy due to the “heavy atom effect.” This dinitrene along with septet trinitrene S1 possess the largest negative value of D among all known quintet and septet organic polyradicals.

  9. High- Tc superconductors with antiferromagnetic order: limitations on spin-fluctuation pairing mechanism

    NASA Astrophysics Data System (ADS)

    Kulić, Miodrag L.; Kulić, Igor M.

    2003-08-01

    The antagonistic interplay of antiferromagnetism (AF) and superconductivity (SC), recently discovered in high-temperature superconductors, is studied in the framework of a microscopic theory. We explain the surprisingly large increase of the magnetic Bragg peak intensity IQ at Q∼( π, π) in the magnetic field H≪ Hc2 at low temperatures 0< T≪ Tc, TAF in La 2- xSr xCuO 4. Good agreement with experimental results is found. The theory predicts large anisotropy of the relative intensity RQ( H)=( IQ( H)- IQ(0))/ IQ(0), i.e. R Q( H∥c -axis)≫R Q( H⊥c -axis) . The quantum ( T=0) phase diagram at H=0 is constructed. The theory also predicts: (i) that the magnetic field can induce the AF order in the SC state; (ii) that the spin-fluctuation (SF) effective coupling constant g<0.1 eV is small, which gives small SC critical temperature Tc (≪40 K)--thus questioning the SF mechanism of pairing in HTS oxides.

  10. In-beam studies of high-spin states of actinide nuclei

    SciTech Connect

    Stoyer, M.A. . Nuclear Science Div. California Univ., Berkeley, CA . Dept. of Chemistry)

    1990-11-15

    High-spin states in the actinides have been studied using Coulomb- excitation, inelastic excitation reactions, and one-neutron transfer reactions. Experimental data are presented for states in {sup 232}U, {sup 233}U, {sup 234}U, {sup 235}U, {sup 238}Pu and {sup 239}Pu from a variety of reactions. Energy levels, moments-of-inertia, aligned angular momentum, Routhians, gamma-ray intensities, and cross-sections are presented for most cases. Additional spectroscopic information (magnetic moments, M{sub 1}/E{sub 2} mixing ratios, and g-factors) is presented for {sup 233}U. One- and two-neutron transfer reaction mechanisms and the possibility of band crossings (backbending) are discussed. A discussion of odd-A band fitting and Cranking calculations is presented to aid in the interpretation of rotational energy levels and alignment. In addition, several theoretical calculations of rotational populations for inelastic excitation and neutron transfer are compared to the data. Intratheory comparisons between the Sudden Approximation, Semi-Classical, and Alder-Winther-DeBoer methods are made. In connection with the theory development, the possible signature for the nuclear SQUID effect is discussed. 98 refs., 61 figs., 21 tabs.

  11. High-spin states in the N=50 nucleus ^87Rb

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Cizewski, J. A.; Krücken, R.; Clark, R. M.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Becker, J. A.; Bernstein, L. A.; McNabb, D. P.; Younes, W.

    2001-10-01

    High-spin states in ^87Rb have been studied following the fission of two compound nuclei (^199Tl and ^197Pb) formed in different fusion-evaporation reactions. The Gammasphere array at LBNL was used to detect γ-ray coincidences. The level scheme has been extended above the previously known 1578 keV, 9/2^+ isomer by observation of many states up to ~7.2 MeV excitation energy. Coupling of the odd g_9/2 proton to the yrast states in the ^86Kr core accounts for the first excited states observed above the 9/2^+ isomer. The level scheme of ^87Rb is also compared to excitations in ^85Kr and the ^89Y isotone. This work has been supported in part by the U.S. Department of Energy under Contracts No. W-7405-ENG-36 (LANL), FG02-91ER-40609 (Yale), W-7405-ENG-48 (LLNL) and AC03-76SF00098 (LBNL) and by the National Science Foundation (Rutgers).

  12. Calculations with the quasirelativistic local-spin-density-functional theory for high-Z atoms

    SciTech Connect

    Guo, Y.; Whitehead, M.A.

    1988-10-01

    The generalized-exchange local-spin-density-functional theory (LSD-GX) with relativistic corrections of the mass velocity and Darwin terms has been used to calculate statistical total energies for the neutral atoms, the positive ions, and the negative ions for high-Z elements. The effect of the correlation and relaxation correction on the statistical total energy is discussed. Comparing the calculated results for the ionization potentials and electron affinities for the atoms (atomic number Z from 37 to 56 and 72 to 80) with experiment, shows that for the atoms rubidium to barium both the LSD-GX and the quasirelativistic LSD-GX, with self-interaction correction, Gopinathan, Whitehead, and Bogdanovic's Fermi-hole parameters (Phys. Rev. A 14, 1 (1976)), and Vosko, Wilk, and Nusair's correlation correction (Can. J. Phys. 58, 1200 (1980)), are very good methods for calculating ionization potentials and electron affinities. For the atoms hafnium to mercury the relativistic effect has to be considered.

  13. Magnetocaloric effect of high-spin cluster with Ni9W6 core

    NASA Astrophysics Data System (ADS)

    Gajewski, M.; Pełka, R.; Fitta, M.; Miyazaki, Y.; Nakazawa, Y.; Bałanda, M.; Reczyński, M.; Nowicka, B.; Sieklucka, B.

    2016-09-01

    A study of magnetocaloric effect of a structurally unique molecular magnet built of spin clusters with the pentadecanuclear Ni(II)9W(V)6 core forming a cube-like framework is reported. The compound crystallizes in the triclinic system. The clusters display anisotropy quantified with the axial D=0.07 K and rhombic E=0.023 K anisotropy constants. The temperature dependences of magnetic entropy change ΔSM as well as the adiabatic temperature change ΔTad due to applied field change μ0ΔH ranging from 1 to 9 T have been determined by employing the relaxation calorimetry measurements in applied field. The maximum value of ΔSM for μ0ΔH=5 T is 18.38 J K-1 mol-1 (3.36 J K-1 kg-1) at 4.3 K. The corresponding maximum value of ΔTad=4.6 K is attained at 2.2 K. The occurrence of the inverse MCE has been observed at high temperatures for small field change values. The temperature dependence of the exponent n characterizing the field dependence of ΔSM has been estimated and discussed. The study revealed that the compound may be treated as a possible candidate for cryogenic magnetic cooling.

  14. Dipole bands in high spin states of {sub 57}{sup 135}La{sub 78}

    SciTech Connect

    Garg, Ritika; Kumar, S.; Saxena, Mansi; Goyal, Savi; Siwal, Davinder; Verma, S.; Mandal, S.; Palit, R.; Saha, Sudipta; Sethi, J.; Sharma, Sushil K.; Trivedi, T.; Jadav, S. K.; Donthi, R.; Naidu, B. S.

    2014-08-14

    High spin states of {sup 135}La have been investigated using the reaction {sup 128}Te({sup 11}B,4n){sup 135}La at a beam energy of 50.5 MeV. Two negative parity dipole bands (ΔI = 1) have been established. Crossover E2 transitions have been observed for the first time in one of the dipole bands. For the Tilted Axis Cranking (TAC) calculations, a three-quasiparticle (3qp) configuration π(h{sub 11/2}){sup 1}⊗ν(h{sub 11/2}){sup −2} and a five-quasiparticle (5qp) configuration π(h{sub 11/2}){sup 1}(g{sub 7/2}/d{sub 5/2}){sup 2}⊗ν(h{sub 11/2}){sup −2} have been taken for the two negative parity dipole bands. The comparison of experimental observables with TAC calculations supports the configuration assignments for both the dipole bands.

  15. High-spin structure and multiphonon {gamma} vibrations in very neutron-rich {sup 114}Ru

    SciTech Connect

    Yeoh, E. Y.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Xiao, Z. G.; Zhu, S. J.; Hamilton, J. H.; Li, K.; Ramayya, A. V.; Hwang, J. K.; Liu, Y. X.; Liu, S. H.; Sheikh, J. A.; Bhat, G. H.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Ma, W. C.

    2011-05-15

    High-spin levels of the neutron-rich {sup 114}Ru have been investigated by measuring the prompt {gamma} rays in the spontaneous fission of {sup 252}Cf. The ground-state band and one-phonon {gamma}-vibrational band have been extended up to 14{sup +} and 9{sup +}, respectively. Two levels are proposed as the members of a two-phonon {gamma}-vibrational band. A back bending (band crossing) has been observed in the ground-state band at ({h_bar}/2{pi}){omega}{approx_equal} 0.40 MeV. Using the triaxial deformation parameters, the cranked shell model calculations indicate that this back bending in {sup 114}Ru should originate from the alignment of a pair of h{sub 11/2} neutrons. Triaxial projected shell model calculations for the {gamma}-vibrational band structures of {sup 114}Ru are in good agreement with the experimental data. However, when using the oblate deformation parameters, both of the above-calculated results are not in agreement with the experimental data.

  16. High spin states in {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr

    SciTech Connect

    Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Liu, S. H.; Brewer, N. T.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Donangelo, R.

    2010-09-15

    High spin states are observed for the first time in the neutron-rich nuclei {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr from the spontaneous fission of {sup 252}Cf. Twenty new transitions in {sup 151}Pr, twelve in {sup 153}Pr, five in {sup 157}Sm, and four in {sup 93}Kr were identified by using x-ray(Pr/Sm)-{gamma}-{gamma} and {gamma}-{gamma}-{gamma} triple coincidences. From the measured total internal conversion coefficients {alpha}{sub T} of four low-energy transitions in {sup 151,153}Pr, we determine that two bands in each nucleus have opposite parity. The interlacing E1 transitions between the bands suggest a form of parity doubling in {sup 151,153}Pr. New bands in {sup 157}Sm and {sup 93}Kr are reported. The half-life of the 354.8 keV state in {sup 93}Kr is measured to be 10(2) ns.

  17. Quantitative neuropathology by high resolution magic angle spinning proton magnetic resonance spectroscopy

    PubMed Central

    Cheng, L. L.; Ma, M. J.; Becerra, L.; Ptak, T.; Tracey, I.; Lackner, A.; González, R. G.

    1997-01-01

    We describe a method that directly relates tissue neuropathological analysis to medical imaging. Presently, only indirect and often tenuous relationships are made between imaging (such as MRI or x-ray computed tomography) and neuropathology. We present a biochemistry-based, quantitative neuropathological method that can help to precisely quantify information provided by in vivo proton magnetic resonance spectroscopy (1HMRS), an emerging medical imaging technique. This method, high resolution magic angle spinning (HRMAS) 1HMRS, is rapid and requires only small amounts of unprocessed samples. Unlike chemical extraction or other forms of tissue processing, this method analyzes tissue directly, thus minimizing artifacts. We demonstrate the utility of this method by assessing neuronal damage using multiple tissue samples from differently affected brain regions in a case of Pick disease, a human neurodegenerative disorder. Among different regions, we found an excellent correlation between neuronal loss shown by traditional neurohistopathology and decrease of the neuronal marker N-acetylaspartate measured by HRMAS 1HMRS. This result demonstrates for the first time, to our knowledge, a direct, quantitative link between a decrease in N-acetylaspartate and neuronal loss in a human neurodegenerative disease. As a quantitative method, HRMAS 1HMRS has potential applications in experimental and clinical neuropathologic investigations. It should also provide a rational basis for the interpretation of in vivo 1HMRS studies of human neurological disorders. PMID:9177231

  18. Synchronization of spin-transfer torque oscillators by spin pumping, inverse spin Hall, and spin Hall effects

    SciTech Connect

    Elyasi, Mehrdad; Bhatia, Charanjit S.; Yang, Hyunsoo

    2015-02-14

    We have proposed a method to synchronize multiple spin-transfer torque oscillators based on spin pumping, inverse spin Hall, and spin Hall effects. The proposed oscillator system consists of a series of nano-magnets in junction with a normal metal with high spin-orbit coupling, and an accumulative feedback loop. We conduct simulations to demonstrate the effect of modulated charge currents in the normal metal due to spin pumping from each nano-magnet. We show that the interplay between the spin Hall effect and inverse spin Hall effect results in synchronization of the nano-magnets.

  19. Specific features of insulator-metal transitions under high pressure in crystals with spin crossovers of 3 d ions in tetrahedral environment

    NASA Astrophysics Data System (ADS)

    Lobach, K. A.; Ovchinnikov, S. G.; Ovchinnikova, T. M.

    2015-01-01

    For Mott insulators with tetrahedral environment, the effective Hubbard parameter U eff is obtained as a function of pressure. This function is not universal. For crystals with d 5 configuration, the spin crossover suppresses electron correlations, while for d 4 configurations, the parameter U eff increases after a spin crossover. For d 2 and d 7 configurations, U eff increases with pressure in the high-spin (HS) state and is saturated after the spin crossover. Characteristic features of the insulator-metal transition are considered as pressure increases; it is shown that there may exist cascades of several transitions for various configurations.

  20. One-step patterning of double tone high contrast and high refractive index inorganic spin-on resist

    SciTech Connect

    Zanchetta, E.; Della Giustina, G.; Brusatin, G.

    2014-09-14

    A direct one-step and low temperature micro-fabrication process, enabling to realize large area totally inorganic TiO₂ micro-patterns from a spin-on resist, is presented. High refractive index structures (up to 2 at 632 nm) without the need for transfer processes have been obtained by mask assisted UV lithography, exploiting photocatalytic titania properties. A distinctive feature not shared by any of the known available resists and boosting the material versatility, is that the system behaves either as a positive or as negative tone resist, depending on the process parameters and on the development chemistry. In order to explain the resist double tone behavior, deep comprehension of the lithographic process parameters optimization and of the resist chemistry and structure evolution during the lithographic process, generally uncommon in literature, is reported. Another striking property of the presented resist is that the negative tone shows a high contrast up to 19, allowing to obtain structures resolution down to 2 μm wide. The presented process and material permit to directly fabricate different titania geometries of great importance for solar cells, photo-catalysis, and photonic crystals applications.

  1. Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol.

    PubMed

    Belov, S P; Golubiatnikov, G Yu; Lapinov, A V; Ilyushin, V V; Alekseev, E A; Mescheryakov, A A; Hougen, J T; Xu, Li-Hong

    2016-07-14

    This paper presents an explanation based on torsionally mediated proton-spin-overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = - 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric "torsionally mediated spin-rotation operators" by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e(±niα). The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A1 and A2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

  2. EDITORIAL: New materials with high spin polarization: half-metallic Heusler compounds

    NASA Astrophysics Data System (ADS)

    Felser, Claudia; Hillebrands, Burkard

    2007-03-01

    The development of magnetic Heusler compounds, specifically designed as materials for spintronic applications, has made tremendous progress in the very recent past [1-21]. Heusler compounds can be made as half-metals, showing a high spin polarization of the conduction electrons of up to 100% [1]. These materials are exceptionally well suited for applications in magnetic tunnel junctions acting, for example, as sensors for magnetic fields. The tunnelling magneto-resistance (TMR) effect is the relative change in the electrical resistance upon application of a small magnetic field. Tunnel junctions with a TMR effect of 580% at 4 K were reported by the group of Miyazaki and Ando [1], consisting of two Co2MnSi Heusler electrodes. High Curie temperatures were found in Co2 Heusler compounds with values up to 1120 K in Co2FeSi [2]. The latest results are for a TMR device made from the Co2FeAl0.5Si0.5 Heusler compound and working at room temperature with a TMR effect of 174% [3]. The first significant magneto-resistance effect was discovered in Co2Cr0.6Fe0.4Al (CCFA) in Mainz [4]. With the classical Heusler compound CCFA as one electrode, the record TMR effect at 4 K is 240% [5]. Positive and negative TMR values at room temperature utilizing magnetic tunnel junctions with one Heusler compound electrode render magnetic logic possible [6]. Research efforts exist, in particular, in Japan and in Germany. The status of research as of winter 2005 was compiled in a recent special volume of Journal of Physics D: Applied Physics [7-20]. Since then specific progress has been made on the issues of (i) new advanced Heusler materials, (ii) advanced characterization, and (iii) advanced devices using the new materials. In Germany, the Mainz and Kaiserslautern based Research Unit 559 `New Materials with High Spin Polarization', funded since 2004 by the Deutsche Forschungsgemeinschaft, is a basic science approach to Heusler compounds, and it addresses the first two topics in particular

  3. Stabilization of the Low-Spin State in a Mononuclear Iron(II) Complex and High-Temperature Cooperative Spin Crossover Mediated by Hydrogen Bonding.

    PubMed

    Zheng, Sipeng; Reintjens, Niels R M; Siegler, Maxime A; Roubeau, Olivier; Bouwman, Elisabeth; Rudavskyi, Andrii; Havenith, Remco W A; Bonnet, Sylvestre

    2016-01-04

    The tetrapyridyl ligand bbpya (bbpya=N,N-bis(2,2'-bipyrid-6-yl)amine) and its mononuclear coordination compound [Fe(bbpya)(NCS)2 ] (1) were prepared. According to magnetic susceptibility, differential scanning calorimetry fitted to Sorai's domain model, and powder X-ray diffraction measurements, 1 is low-spin at room temperature, and it exhibits spin crossover (SCO) at an exceptionally high transition temperature of T1/2 =418 K. Although the SCO of compound 1 spans a temperature range of more than 150 K, it is characterized by a wide (21 K) and dissymmetric hysteresis cycle, which suggests cooperativity. The crystal structure of the LS phase of compound 1 shows strong NH⋅⋅⋅S intermolecular H-bonding interactions that explain, at least in part, the cooperative SCO behavior observed for complex 1. DFT and CASPT2 calculations under vacuum demonstrate that the bbpya ligand generates a stronger ligand field around the iron(II) core than its analogue bapbpy (N,N'-di(pyrid-2-yl)-2,2'-bipyridine-6,6'-diamine); this stabilizes the LS state and destabilizes the HS state in 1 compared with [Fe(bapbpy)(NCS)2 ] (2). Periodic DFT calculations suggest that crystal-packing effects are significant for compound 2, in which they destabilize the HS state by about 1500 cm(-1) . The much lower transition temperature found for the SCO of 2 compared to 1 appears to be due to the combined effects of the different ligand field strengths and crystal packing.

  4. Spin Choreography: Basic Steps in High Resolution NMR (by Ray Freeman)

    NASA Astrophysics Data System (ADS)

    Minch, Michael J.

    1998-02-01

    There are three orientations that NMR courses may take. The traditional molecular structure course focuses on the interpretation of spectra and the use of chemical shifts, coupling constants, and nuclear Overhauser effects (NOE) to sort out subtle details of structure and stereochemistry. Courses can also focus on the fundamental quantum mechanics of observable NMR parameters and processes such a spin-spin splitting and relaxation. More recently there are courses devoted to the manipulation of nuclear spins and the basic steps of one- and two-dimensional NMR experiments. Freeman's book is directed towards the latter audience. Modern NMR methods offer a myriad ways to extract information about molecular structure and motion by observing the behavior of nuclear spins under a variety of conditions. In Freeman's words: "We can lead the spins through an intricate dance, carefully programmed in advance, to enhance, simplify, correlate, decouple, edit or assign NMR spectra." This is a carefully written, well-illustrated account of how this dance is choreographed by pulse programming, double resonance, and gradient effects. Although well written, this book is not an easy read; every word counts. It is recommended for graduate courses that emphasize the fundamentals of magnetic resonance. It is not a text on interpretation of spectra.

  5. Measuring the Spin-Down Rate of a High-Velocity Pulsar

    NASA Astrophysics Data System (ADS)

    Tomsick, John

    2013-10-01

    The X-ray and radio morphology of IGR J11014-6103 strongly suggest that it is an energetic pulsar/PWN moving away from the center of the SNR MSH 11-61A at an extraordinarily large velocity of >2,400 km/s. Using XMM-Newton, we recently discovered 62.8 ms pulsations from IGR J11014-6103. Now, we need to measure the spin-down rate of PSR J1101-6101 in order to determine its spin-down power and spin-down age. The spin-down power is needed to understand the structure of its apparent bow-shock nebula and mysterious X-ray streak. The spin-down age is an upper limit on its true age, and will establish whether PSR J1101-6101 could have originated in MSH 11-61A, which would make it the pulsar with the largest known natal kick velocity.

  6. Magnetotransport in high mobility InSbCdTe heterojunctions: Electric spin-splitting of subbands and high pressure effects

    NASA Astrophysics Data System (ADS)

    Singleton, J.; Greene, S. K.; Golding, T. D.; Pepper, M.; Skierbiszewski, C.; Wisniewski, P.; van der Wel, P. J.; van Thor, P. H. E.; Dinan, J.

    Magneto-transport measurements are reported on the high-mobility, low-carrier-density (μ = 16 000 - 22 000 cm 2V -1s -1 and Ns = 1.8 - 4.2 × 10 11 cm -2), two dimensional electron gas in InSbCdTe heterojunctions, realised as a result of improvements in growth techniques. Measurements carried out at hydrostatic pressures up to 10 kbar show that Ns decreases with increasing pressure, suggesting that the electrons in the 2DEG originate from a band of interface states ˜ 100 meV above the InSb conduction band edge at the InSbCdTe interface. The temperature dependence of the Hall effect suggests that the persistent photoconductivity observed in InSbCdTe heterojunctions is due to charge separation in InSb. The low-field magnetoresistance of the heterojunctions is at first positive and then negative due to the presence of a spin-splitting of the subbands of around 3 meV at the Fermi energy, present even in zero applied magnetic field, and the experimental results aer compared with self-consistent calculations of this effect.

  7. Geometrical Spin Frustration of Unusually High Valence Fe(5+) in the Double Perovskite La2LiFeO6.

    PubMed

    Xiong, Peng; Seki, Hayato; Guo, Haichuan; Hosaka, Yoshiteru; Saito, Takashi; Mizumaki, Masaichiro; Shimakawa, Yuichi

    2016-06-20

    A double perovskite-structure oxide La2LiFeO6 with unusually high-valence Fe(5+) was synthesized using a high-pressure technique. The Li(+) and Fe(5+) ions at the B site in the rhombohedral R3̅ perovskite structure are ordered in a rock salt manner, and the resultant tetrahedral network of Fe(5+) gives geometrical spin frustration, which is consistent with a large frustration index f (|θ|/TN) ≈ 10. Mg(2+) substitution for Li(+) produces Fe(4+) from some Fe(5+) and changes the magnetic properties. The Weiss temperature is increased from -119 to 21 K by the substitution of only 1%, significantly decreasing the frustration index. The geometrical frustration of the Fe(5+) spin sublattice cannot be tolerant for even a very small amount of Fe(4+) disturbance.

  8. Enhancement of high-spin collectivity in N = Z nuclei by the isoscalar neutron-proton pairing

    NASA Astrophysics Data System (ADS)

    Kaneko, K.; Sun, Y.; de Angelis, G.

    2017-01-01

    Pairing from different fermions, neutrons and protons, is unique in nuclear physics. The fingerprint for the isoscalar T = 0 neutron-proton (np) pairing has however remained a question. We study this exotic pairing mode in excited states of rotating N ≈ Z nuclei by applying the state-of-the-art shell-model calculations for 88Ru and the neighboring 90,92Ru isotopes. We show that the T = 0 np pairing is responsible for the distinct rotational behavior between the N = Z and N > Z nuclei. Our calculation suggests a gradual crossover from states with mixed T = 1 and T = 0 pairing near the ground state to those dominated by the T = 0 np pairing at high spins. It is found that the T = 0 np pairing plays an important role in enhancing the high-spin collectivity, thereby reducing shape variations along the N = Z line.

  9. High-spin level structure of {sup 115}Rh: Evolution of triaxiality in odd-even Rh isotopes

    SciTech Connect

    Liu, S. H.; Gelberg, A.; Gu, L.; Yeoh, E. Y.; Zhu, S. J.; Luo, Y. X.; Rasmussen, J. O.; Ma, W. C.; Daniel, A. V.; Oganessian, Yu. Ts.; Ter-Akopian, G. M.

    2011-07-15

    High-spin excited states in the neutron-rich nucleus {sup 115}Rh have been identified for the first time by studying prompt {gamma} rays from the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A new yrast band and a sideband are built in {sup 115}Rh. This level scheme is proposed to be built on the 7/2{sup +} ground state. The existence of a large signature splitting and an yrare band in {sup 115}Rh shows typical features of a triaxially deformed nucleus. The rigid triaxial rotor plus particle model is used to interpret the level structure of {sup 115}Rh. The level energies, the {gamma} branching ratios, the large signature splitting in the yrast band, and the inverted signature splitting in the yrare band in {sup 115}Rh are reproduced very well. Strong K mixing occurs in {sup 115}Rh at high spin.

  10. Exploration of spin-down rate of neutron stars in high-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Dai, Hai-Lang; Liu, Xi-Wei; Li, Xiang-Dong

    2016-04-01

    We use the evolutionary population synthesis method to investigate the statistical properties of the wind-fed neutron-star (NS) compact (Porb < 10 d) high-mass X-ray binaries (HMXBs) in our Galaxy, based on different spin-down models. Model 1 assumes that the surrounding material is treated as forming a quasi-static atmosphere. Model 2 assumes that the characteristic velocity of matter and the typical Alfvén velocity of material in the magnetospheric boundary layer are comparable to the sound speed in the external medium. We find that the spin-down rate in the supersonic propeller phase in either model 1 or model 2 is too low to produce the observed number of compact HMXBs. Model 3 assumes that the infalling material is ejected with the corotation velocity at the magnetospheric radius when the magnetospheric radius is larger than the corotation radius. Model 4 uses simple integration of the magnetic torque over the magnetosphere. Both models 3 and 4 have a larger spin down rate than that given by model 1 or 2. We also find that models 3 and 4 can predict a reasonable number of observed wind-fed NS compact HMXBs. By comparing our calculated results with the observed particular distributions of wind-fed NS compact HMXBs in a Ps versus Porb diagram, we find that the subsonic propeller phase may not exist at all. However, the spin-down rates in models 3 and 4 both seem reasonable to produce the observed distribution of wind-fed NS compact HMXBs in the Ps versus Porb diagram. We cannot find which spin-down rate seems more reasonable from our calculations.

  11. Structural properties and high-temperature spin and electronic transitions in GdCoO3: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Orlov, Yu. S.; Solovyov, L. A.; Dudnikov, V. A.; Fedorov, A. S.; Kuzubov, A. A.; Kazak, N. V.; Voronov, V. N.; Vereshchagin, S. N.; Shishkina, N. N.; Perov, N. S.; Lamonova, K. V.; Babkin, R. Yu; Pashkevich, Yu. G.; Anshits, A. G.; Ovchinnikov, S. G.

    2013-12-01

    We have investigated the x-ray diffraction (XRD) structure, magnetic susceptibility, and heat capacity of GdCoO3 in a wide temperature range. A model of phase separation of the low-spin (LS) and high-spin (HS) states has been proposed based on the analysis of XRD peak shape anomalies in the temperature range 200-800 K. From magnetic measurements we separated the HS Co3+ contribution and fitted it with the temperature-dependent spin gap. We found a smooth LS-HS crossover at T=800 K. The possible contribution of the intermediate spin (IS) state to the thermodynamics is excluded by the calculation IS-LS excitation energy within the modified crystal-field approach. In the two-phase model, with HS/LS probabilities calculated from the found spin gap and the LS and HS volumes calculated by the DFT-GGA method, we were able to reproduce the temperature dependence of the unit-cell volume and thermal expansion. Thus, we conclude that in GdCoO3 the main mechanism of the lattice expansion is not the conventional lattice anharmonicity, but the HS/LS fluctuations. The electronic structure has been calculated by the LDA+GTB method. At zero temperature, we have obtained the charge-transfer insulator with the charge gap Eg=0.5 eV. The thermal population of the HS term results in the in-gap band formation inside the insulator gap and smooth insulator-metal transition at TIMT=780 K. Heat-capacity measurements revealed a smooth maximum near the TIMT.

  12. Highly Efficient Spin-Current Operation in a Cu Nano-Ring

    PubMed Central

    Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

    2016-01-01

    An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic. PMID:27869213

  13. Highly relativistic spinning particle starting near rph(-) in a Kerr field

    NASA Astrophysics Data System (ADS)

    Plyatsko, Roman; Stefanyshyn, Oleksandr; Fenyk, Mykola

    2010-08-01

    Using the Mathisson-Papapetrou-Dixon equations, we investigate the trajectories of a spinning particle starting near rph(-) in a Kerr field and moving with the velocity close to the velocity of light (rph(-) is the Boyer-Lindquist radial coordinate of the counter-rotation circular photon orbits). First, as a partial case of these trajectories, we consider the equatorial circular orbit with r=rph(-). This orbit is described by the solution that is common for the rigorous Mathisson-Papapetrou-Dixon equations and their linear spin approximation. Then different cases of the nonequatorial motions are computed and illustrated by the typical figures. All these orbits exhibit the effects of the significant gravitational repulsion that are caused by the spin-gravity interaction. Possible applications in astrophysics are discussed.

  14. Nuclear energy surfaces at high-spin in the A{approximately}180 mass region

    SciTech Connect

    Chasman, R.R.; Egido, J.L.; Robledo, L.M.

    1995-08-01

    We are studying nuclear energy surfaces at high spin, with an emphasis on very deformed shapes using two complementary methods: (1) the Strutinsky method for making surveys of mass regions and (2) Hartree-Fock calculations using a Gogny interaction to study specific nuclei that appear to be particularly interesting from the Strutinsky method calculations. The great advantage of the Strutinsky method is that one can study the energy surfaces of many nuclides ({approximately}300) with a single set of calculations. Although the Hartree-Fock calculations are quite time-consuming relative to the Strutinsky calculations, they determine the shape at a minimum without being limited to a few deformation modes. We completed a study of {sup 182}Os using both approaches. In our cranked Strutinsky calculations, which incorporate a necking mode deformation in addition to quadrupole and hexadecapole deformations, we found three well-separated, deep, strongly deformed minima. The first is characterized by nuclear shapes with axis ratios of 1.5:1; the second by axis ratios of 2.2:1 and the third by axis ratios of 2.9:1. We also studied this nuclide with the density-dependent Gogny interaction at I = 60 using the Hartree-Fock method and found minima characterized by shapes with axis ratios of 1.5:1 and 2.2:1. A comparison of the shapes at these minima, generated in the two calculations, shows that the necking mode of deformation is extremely useful for generating nuclear shapes at large deformation that minimize the energy. The Hartree-Fock calculations are being extended to larger deformations in order to further explore the energy surface in the region of the 2.9:1 minimum.

  15. Nonadiabatic spin transfer torque in high anisotropy magnetic nanowires with narrow domain walls.

    PubMed

    Boulle, O; Kimling, J; Warnicke, P; Kläui, M; Rüdiger, U; Malinowski, G; Swagten, H J M; Koopmans, B; Ulysse, C; Faini, G

    2008-11-21

    Current induced domain wall (DW) depinning of a narrow DW in out-of-plane magnetized (Pt/Co)_{3}/Pt multilayer elements is studied by magnetotransport. We find that for conventional measurements Joule heating effects conceal the real spin torque efficiency and so we use a measurement scheme at a constant sample temperature to unambiguously extract the spin torque contribution. From the variation of the depinning magnetic field with the current pulse amplitude we directly deduce the large nonadiabaticity factor in this material and we find that its amplitude is consistent with a momentum transfer mechanism.

  16. High-Frequency Spin-Based Devices for Nanoscale Signal Processing

    DTIC Science & Technology

    2009-01-20

    have found that single STNO devices that incorporate Co/Ni multilayers as the free layer routinely have power outputs of roughly 20 nW (Fig. 3), and...those in all-metal spin-valve multilayer samples that have a similar geometry for the magnetic free layer. However, we have discovered that...derivative of the spin torque with respect to current, MSVol is the total magnetic moment of the free layer, and  is the FMR linewidth. In general, d/dI

  17. Spin spring behavior in exchange coupled soft and high-coercivity hard ferromagnets.

    SciTech Connect

    Shull, R. D.; Shapiro, A. J.; Gornakov, V. S.; Nikitenko, V. I.; Jiang, J. S.; Kaper, H.; Leaf, G.; Bader, S. D.

    2000-11-01

    The magnetization reversal processes in an epitaxial Fe/Sm{sub 2}Co{sub 7} structure were investigated using the magneto-optical indicator film technique. The dependence of the magnitude and the orientation of the structure average magnetization have been studied on both cycling and rotating the external magnetic field. It was discovered that the magnetization reversal of the soft ferromagnet can proceed by formation of not only one-dimensional, but also two-dimensional, exchange spin springs. Experimental data is compared with a theoretical estimation of the rotational hysteresis loop for a spin system containing a one-dimensional exchange spring.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  19. Mesoscopic superconductivity and high spin polarization coexisting at metallic point contacts on Weyl semimetal TaAs

    PubMed Central

    Aggarwal, Leena; Gayen, Sirshendu; Das, Shekhar; Kumar, Ritesh; Süß, Vicky; Felser, Claudia; Shekhar, Chandra; Sheet, Goutam

    2017-01-01

    A Weyl semimetal is a topologically non-trivial phase of matter that hosts mass-less Weyl fermions, the particles that remained elusive for more than 80 years since their theoretical discovery. The Weyl semimetals exhibit unique transport properties and remarkably high surface spin polarization. Here we show that a mesoscopic superconducting phase with critical temperature Tc=7 K can be realized by forming metallic point contacts with silver (Ag) on single crystals of TaAs, while neither Ag nor TaAs are superconductors. Andreev reflection spectroscopy of such point contacts reveals a superconducting gap of 1.2 meV that coexists with a high transport spin polarization of 60% indicating a highly spin-polarized supercurrent flowing through the point contacts on TaAs. Therefore, apart from the discovery of a novel mesoscopic superconducting phase, our results also show that the point contacts on Weyl semimetals are potentially important for applications in spintronics. PMID:28071685

  20. THE MOST MASSIVE ACTIVE BLACK HOLES AT z ∼ 1.5-3.5 HAVE HIGH SPINS AND RADIATIVE EFFICIENCIES

    SciTech Connect

    Trakhtenbrot, Benny

    2014-07-01

    The radiative efficiencies (η) of 72 luminous unobscured active galactic nuclei at z ∼ 1.5-3.5, powered by some of the most massive black holes (BHs), are constrained. The analysis is based on accretion disk (AD) models, which link the continuum luminosity at rest-frame optical wavelengths and the BH mass (M {sub BH}) to the accretion rate through the AD, M-dot {sub AD}. The data are gathered from several literature samples with detailed measurements of the Hβ emission line complex, observed at near-infrared bands. When coupled with standard estimates of bolometric luminosities (L {sub bol}), the analysis suggests high radiative efficiencies, with most of the sources showing η > 0.2, that is, higher than the commonly assumed value of 0.1, and the expected value for non-spinning BHs (η = 0.057). Even under more conservative assumptions regarding L {sub bol} (i.e., L {sub bol} = 3 × L {sub 5100}), most of the extremely massive BHs in the sample (i.e., M {sub BH} ≳ 3 × 10{sup 9} M {sub ☉}) show radiative efficiencies which correspond to very high BH spins (a {sub *}), with typical values well above a {sub *} ≅ 0.7. These results stand in contrast to the predictions of a ''spin-down'' scenario, in which a series of randomly oriented accretion episodes leads to a {sub *} ∼ 0. Instead, the analysis presented here strongly supports a ''spin-up'' scenario, which is driven by either prolonged accretion or a series of anisotropically oriented accretion episodes. Considering the fact that these extreme BHs require long-duration or continuous accretion to account for their high masses, it is argued that the most probable scenario for the super-massive black holes under study is that of an almost continuous sequence of randomly yet not isotropically oriented accretion episodes.

  1. Rapid high-resolution spin- and angle-resolved photoemission spectroscopy with pulsed laser source and time-of-flight spectrometer

    SciTech Connect

    Gotlieb, K.; Hussain, Z.; Bostwick, A.; Jozwiak, C.; Lanzara, A.

    2013-09-15

    A high-efficiency spin- and angle-resolved photoemission spectroscopy (spin-ARPES) spectrometer is coupled with a laboratory-based laser for rapid high-resolution measurements. The spectrometer combines time-of-flight (TOF) energy measurements with low-energy exchange scattering spin polarimetry for high detection efficiencies. Samples are irradiated with fourth harmonic photons generated from a cavity-dumped Ti:sapphire laser that provides high photon flux in a narrow bandwidth, with a pulse timing structure ideally matched to the needs of the TOF spectrometer. The overall efficiency of the combined system results in near-E{sub F} spin-resolved ARPES measurements with an unprecedented combination of energy resolution and acquisition speed. This allows high-resolution spin measurements with a large number of data points spanning multiple dimensions of interest (energy, momentum, photon polarization, etc.) and thus enables experiments not otherwise possible. The system is demonstrated with spin-resolved energy and momentum mapping of the L-gap Au(111) surface states, a prototypical Rashba system. The successful integration of the spectrometer with the pulsed laser system demonstrates its potential for simultaneous spin- and time-resolved ARPES with pump-probe based measurements.

  2. Spin crossover in [ MnIII (pyrol)3 tren] probed by high-pressure and low-temperature x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Guionneau, Philippe; Marchivie, Mathieu; Garcia, Yann; Howard, Judith A. K.; Chasseau, Daniel

    2005-12-01

    The interplay between the solid-state spin-crossover features and the structural properties is analyzed for the [MnIII(pyrol)3tren] complex on the basis of high-pressure and low-temperature single-crystal x-ray-diffraction experiments. In particular, the low-temperature ( 30K , 105Pa ) low spin crystal structure is compared to the low-temperature ( 60K , 105Pa ) high spin and to the high-pressure ( 293K , 1.00GPa ) high spin crystal structures. The low-temperature structural properties show the structural modifications due to the spin crossover in a Mn(III) complex. Comparison of these structural modifications to those described for mononuclear Fe(II) spin-crossover compounds emphasizes significant differences, such as in bond length variation and polyhedron distortion, for example. Elsewhere, analysis of the high-pressure data shows that the internal stress on the metal ion is not the cause of the occurrence of the thermal spin crossover, contrary to a general belief.

  3. Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone.

    PubMed

    Devi, V S Anusuya; Reddy, V Krishna

    2012-01-01

    Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individually and simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II) to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximum absorbance of these complexes was found at 405 nm and 425 nm, respectively. For [Fe(II)-HNAHBH], Beer's law is obeyed over the concentration range of 0.055-1.373 μg mL(-1) with a detection limit of 0.095 μg mL(-1) and molar absorptivity ɛ, 5.6 × 10(4) L mol(-1) cm(-1). [Co(II)-HNAHBH] complex obeys Beer's law in 0.118-3.534 μg mL(-1) range with a detection limit of 0.04 μg mL(-1) and molar absorptivity, ɛ of 2.3 × 10(4) L mol(-1) cm(-1). Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content.

  4. Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand.

    PubMed

    Kamble, Ganesh S; Ghare, Anita A; Kolekar, Sanjay S; Han, Sung H; Anuse, Mansing A

    2011-12-15

    A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL(-1) of cobalt(II) and optimum concentration range was 5-12.5 μg mL(-1) of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109×10(3) L mol(-1) cm(-1) and 0.053 μg cm(-2), respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22×10(2) L mol(-1) cm(-1) and 0.096 μg cm(-2), respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n=5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

  5. Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

    NASA Astrophysics Data System (ADS)

    Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

    2011-12-01

    A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

  6. High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature

    NASA Astrophysics Data System (ADS)

    Trifunovic, Luka; Pedrocchi, Fabio L.; Hoffman, Silas; Maletinsky, Patrick; Yacoby, Amir; Loss, Daniel

    2015-06-01

    Magnetic resonance techniques not only provide powerful imaging tools that have revolutionized medicine, but they have a wide spectrum of applications in other fields of science such as biology, chemistry, neuroscience and physics. However, current state-of-the-art magnetometers are unable to detect a single nuclear spin unless the tip-to-sample separation is made sufficiently small. Here, we demonstrate theoretically that by placing a ferromagnetic particle between a nitrogen-vacancy magnetometer and a target spin, the magnetometer sensitivity is improved dramatically. Using materials and techniques that are already experimentally available, our proposed set-up is sensitive enough to detect a single nuclear spin within ten milliseconds of data acquisition at room temperature. The sensitivity is practically unchanged when the ferromagnet surface to the target spin separation is smaller than the ferromagnet lateral dimensions; typically about a tenth of a micrometre. This scheme further benefits when used for nitrogen-vacancy ensemble measurements, enhancing sensitivity by an additional three orders of magnitude.

  7. Quadratic Zeeman effect and spin-lattice relaxation of Tm3 +:YAG at high magnetic fields

    NASA Astrophysics Data System (ADS)

    Veissier, Lucile; Thiel, Charles W.; Lutz, Thomas; Barclay, Paul E.; Tittel, Wolfgang; Cone, Rufus L.

    2016-11-01

    Anisotropy of the quadratic Zeeman effect for the H36→H34 transition at 793 nm wavelength in 3+169Tm-doped Y3Al5O12 is studied, revealing shifts ranging from near zero up to +4.69 GHz/T 2 for ions in magnetically inequivalent sites. This large range of shifts is used to spectrally resolve different subsets of ions and study nuclear spin relaxation as a function of temperature, magnetic field strength, and orientation in a site-selective manner. A rapid decrease in spin lifetime is found at large magnetic fields, revealing the weak contribution of direct phonon absorption and emission to the nuclear spin-lattice relaxation rate. We furthermore confirm theoretical predictions for the phonon coupling strength, finding much smaller values than those estimated in the limited number of past studies of thulium in similar crystals. Finally, we observe a significant—and unexpected—magnetic field dependence of the two-phonon Orbach spin relaxation process at higher field strengths, which we explain through changes in the electronic energy-level splitting arising from the quadratic Zeeman effect.

  8. Corroborative models of the cobalt(II) inhibited Fe/Mn superoxide dismutases.

    PubMed

    Scarpellini, Marciela; Wu, Amy J; Kampf, Jeff W; Pecoraro, Vincent L

    2005-07-11

    Attempting to model superoxide dismutase (SOD) enzymes, we designed two new N3O-donor ligands to provide the same set of donor atoms observed in the active site of these enzymes: K(i)Pr2TCMA (potassium 1,4-diisopropyl-1,4,7-triazacyclononane-N-acetate) and KBPZG (potassium N,N-bis(3,5-dimethylpyrazolylmethyl) glycinate). Five new Co(II) complexes (1-5) were obtained and characterized by X-ray crystallography, mass spectrometry, electrochemistry, magnetochemistry, UV-vis, and electron paramagnetic resonance (EPR) spectroscopies. The crystal structures of 1 and 3-5 revealed five-coordinate complexes, whereas complex 2 is six-coordinate. The EPR data of complexes 3 and 4 agree with those of the Co(II)-substituted SOD, which strongly support the proposition that the active site of the enzyme structurally resembles these models. The redox behavior of complexes 1-5 clearly demonstrates the stabilization of the Co(II) state in the ligand field provided by these ligands. The irreversibility displayed by all of the complexes is probably related to an electron-transfer process followed by a rearrangement of the geometry around the metal center for complexes 1 and 3-5 that probably changes from a trigonal bipyramidal (high spin, d7) to octahedral (low spin, d6) as Co(II) is oxidized to Co(III), which is also expected to be accompanied by a spin-state conversion. As the redox potentials to convert the Co(II) to Co(III) are high, it can be inferred that the redox potential of the Co(II)-substituted SOD may be outside the range required to convert the superoxide radical (O2*-) to hydrogen peroxide, and this is sufficient to explain the inactivity of the enzyme. Finally, the complexes reported here are the first corroborative structural models of the Co(II)-substituted SOD.

  9. Spin Polarized Transport and Spin Relaxation in Quantum Wires

    NASA Astrophysics Data System (ADS)

    Wenk, Paul; Yamamoto, Masayuki; Ohe, Jun-Ichiro; Ohtsuki, Tomi; Kramer, Bernhard; Kettemann, Stefan

    We give an introduction to spin dynamics in quantum wires. After a review of spin-orbit coupling (SOC) mechanisms in semiconductors, the spin diffusion equation with SOC is introduced. We discuss the particular conditions in which solutions of the spin diffusion equation with vanishing spin relaxation rates exist, where the spin density forms persistent spin helices. We give an overview of spin relaxation mechanisms, with particular emphasis on the motional narrowing mechanism in disordered conductors, the D'yakonov-Perel' spin relaxation. The solution of the spin diffusion equation in quantum wires shows that the spin relaxation becomes diminished when reducing the wire width below the spin precession length L SO. This corresponds to an effective alignment of the spin-orbit field in quantum wires and the formation of persistent spin helices whose form as well as amplitude is a measure of the particular SOCs, the linear Rashba and the linear Dresselhaus coupling. Cubic Dresselhaus coupling is found to yield in diffusive wires an undiminished contribution to the spin relaxation rate, however. We discuss recent experimental results which confirm the reduction of the spin relaxation rate. We next review theoretical proposals for creating spin-polarized currents in a T-shape structure with Rashba-SOC. For relatively small SOC, high spin polarization can be obtained. However, the corresponding conductance has been found to be small. Due to the self-duality of the scattering matrix for a system with spin-orbit interaction, no spin polarization of the current can be obtained for single-channel transport in two-terminal devices. Therefore, one has to consider at least a conductor with three terminals. We review results showing that the amplitude of the spin polarization becomes large if the SOC is sufficiently strong. We argue that the predicted effect should be experimentally accessible in InAs. For a possible experimental realization of InAs spin filters, see [1].

  10. Evaluating Human Breast Ductal Carcinomas with High-Resolution Magic-Angle Spinning Proton Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Leo Ling; Chang, I.-Wen; Smith, Barbara L.; Gonzalez, R. Gilberto

    1998-11-01

    We report the results of a study of human breast ductal carcinomas, conducted by using high resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS 1HMRS). This recently developed spectroscopic technique can measure tissue metabolism from intact pathological specimens and identify tissue biochemical changes, which closely correspond to tumorin vivostate. This procedure objectively indicates diagnostic parameters, independent of the skill and experience of the investigator, and has the potential to reduce the sampling errors inherently associated with procedures of conventional histopathology. In this study, we measured 19 cases of female ductal carcinomas. Our results demonstrate that: (1) highly resolved spectra of intact specimens of human breast ductal carcinomas can be obtained; (2) carcinoma-free tissues and carcinomas are distinguishable by alterations in the intensities and the spin-spin relaxation time T2 of cellular metabolites; and (3) tumor metabolic markers, such as phosphocholine, lactate, and lipids, may correlate with the histopathological grade determined from evaluation of the adjacent specimen. Our results suggest that biochemical markers thus measured may function as a valuable adjunct to histopathology to improve the accuracy of and reduce the time frame required for the diagnosis of human breast cancer.

  11. High-spin Mn-oxo complexes and their relevance to the oxygen-evolving complex within photosystem II.

    PubMed

    Gupta, Rupal; Taguchi, Taketo; Lassalle-Kaiser, Benedikt; Bominaar, Emile L; Yano, Junko; Hendrich, Michael P; Borovik, A S

    2015-04-28

    The structural and electronic properties of a series of manganese complexes with terminal oxido ligands are described. The complexes span three different oxidation states at the manganese center (III-V), have similar molecular structures, and contain intramolecular hydrogen-bonding networks surrounding the Mn-oxo unit. Structural studies using X-ray absorption methods indicated that each complex is mononuclear and that oxidation occurs at the manganese centers, which is also supported by electron paramagnetic resonance (EPR) studies. This gives a high-spin Mn(V)-oxo complex and not a Mn(IV)-oxy radical as the most oxidized species. In addition, the EPR findings demonstrated that the Fermi contact term could experimentally substantiate the oxidation states at the manganese centers and the covalency in the metal-ligand bonding. Oxygen-17-labeled samples were used to determine spin density within the Mn-oxo unit, with the greatest delocalization occurring within the Mn(V)-oxo species (0.45 spins on the oxido ligand). The experimental results coupled with density functional theory studies show a large amount of covalency within the Mn-oxo bonds. Finally, these results are examined within the context of possible mechanisms associated with photosynthetic water oxidation; specifically, the possible identity of the proposed high valent Mn-oxo species that is postulated to form during turnover is discussed.

  12. Transverse double-spin asymmetries for electroweak gauge-boson production in high-energy polarized p-> + p-> collisions

    NASA Astrophysics Data System (ADS)

    Surrow, Bernd; Soffer, Jacques; Bourrely, Claude

    2016-09-01

    The collision of high-energy polarized proton beams at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory provides a powerful way to gain a deeper insight into the spin structure and dynamics of the proton such as the study of the helicity distributions of gluons and quarks / antiquarks based on well established high-energy QCD and W boson processes, respectively. Several studies have been suggested in the past to gain a better understanding of the transversity distribution, in particular the measurement of the transverse double-spin asymmetries (ATT) for Drell-Yan production. Prior NLO calculations for Drell-Yan γ / Z exchange have been used to evaluate ATT for Z production using maximal bounds for the transversity distribution. The transverse double-spin asymmetry for W production is expected to be zero. The status of ATT NLO calculations specifically for γ / Z exchange will be discussed using maximal bounds of transversity distributions within the framework by Bourrely and Soffer.

  13. Single shot spin readout with a cryogenic high-electron-mobility transistor amplifier at sub-Kelvin temperatures

    DOE PAGES

    Tracy, Lisa A.; Luhman, Dwight R.; Carr, Stephen M.; ...

    2016-02-08

    We use a cryogenic high-electron-mobility transistor circuit to amplify the current from a single electron transistor, allowing for demonstration of single shot readout of an electron spin on a single P donor in Si with 100 kHz bandwidth and a signal to noise ratio of ~9. In order to reduce the impact of cable capacitance, the amplifier is located adjacent to the Si sample, at the mixing chamber stage of a dilution refrigerator. For a current gain of ~2.7 x 103 the power dissipation of the amplifier is 13 μW, the bandwidth is ~1.3 MHz, and for frequencies above 300more » kHz the current noise referred to input is ≤ 70 fA/√Hz. Furthermore, with this amplification scheme, we are able to observe coherent oscillations of a P donor electron spin in isotopically enriched 28Si with 96% visibility.« less

  14. Single shot spin readout with a cryogenic high-electron-mobility transistor amplifier at sub-Kelvin temperatures

    SciTech Connect

    Tracy, Lisa A.; Luhman, Dwight R.; Carr, Stephen M.; Bishop, Nathaniel C.; Ten Eyck, Gregory A.; Pluym, Tammy; Wendt, Joel R.; Lilly, Michael P.; Carroll, Malcolm S.

    2016-02-08

    We use a cryogenic high-electron-mobility transistor circuit to amplify the current from a single electron transistor, allowing for demonstration of single shot readout of an electron spin on a single P donor in Si with 100 kHz bandwidth and a signal to noise ratio of ~9. In order to reduce the impact of cable capacitance, the amplifier is located adjacent to the Si sample, at the mixing chamber stage of a dilution refrigerator. For a current gain of ~2.7 x 103 the power dissipation of the amplifier is 13 μW, the bandwidth is ~1.3 MHz, and for frequencies above 300 kHz the current noise referred to input is ≤ 70 fA/√Hz. Furthermore, with this amplification scheme, we are able to observe coherent oscillations of a P donor electron spin in isotopically enriched 28Si with 96% visibility.

  15. Test of the Anti-de Sitter-Space/Conformal-Field-Theory Correspondence Using High-Spin Operators

    SciTech Connect

    Benna, M. K.; Benvenuti, S.; Klebanov, I. R.; Scardicchio, A.

    2007-03-30

    In two remarkable recent papers the planar perturbative expansion was proposed for the universal function of the coupling appearing in the dimensions of high-spin operators of the N=4 super Yang-Mills theory. We study numerically the integral equation derived by Beisert, Eden, and Staudacher, which resums the perturbative series. In a confirmation of the anti-de Sitter-space/conformal-field-theory (AdS/CFT) correspondence, we find a smooth function whose two leading terms at strong coupling match the results obtained for the semiclassical folded string spinning in AdS{sub 5}. We also make a numerical prediction for the third term in the strong coupling series.

  16. Electrical control of quantum-dot fine-structure splitting for high-fidelity hole spin initialization

    NASA Astrophysics Data System (ADS)

    Mar, J. D.; Baumberg, J. J.; Xu, X. L.; Irvine, A. C.; Williams, D. A.

    2016-01-01

    We demonstrate electrical control of the neutral exciton fine-structure splitting in a single InAs/GaAs self-assembled quantum dot by significantly reducing the splitting to near zero through the application of a vertical electric field in the fast electron tunneling regime. This is verified by performing high-resolution photocurrent spectroscopy of the two fine-structure split exciton eigenstates as a function of reverse bias voltage. Using the qubit initialization scheme for a quantum-dot hole spin based on rapid electric-field ionization of a spin-polarized exciton, our results suggest a practical approach towards achieving qubit initialization with near-unity fidelity in the absence of magnetic fields.

  17. Contrasting behavior in octupole structures observed at high spin in {sup 220}Ra and {sup 222}Th

    SciTech Connect

    Smith, J.F.; Cocks, J.F.C.; Schulz, N.; Aieche, M.; Bentaleb, M.; Butler, P.A.; Hannachi, F.; Jones, G.D.; Jones, P.M.; Julin, R.; Juutinen, S.; Kulessa, R.; Lubkiewicz, E.; Plochocki, A.; Riess, F.; Ruchowska, E.; Savelius, A.; Sens, J.C.; Simpson, J.; Wolf, E. |||||||

    1995-08-07

    Alternating-parity states connected by strong {ital E}1 transitions, characteristic of a reflection-asymmetric rotor, have been observed to high spins in the isotones {sup 220}Ra and {sup 222}Th. This level structure is observed up to {ital J}{sup {pi}}=29{sup {minus}}(31{sup {minus}}) in {sup 220}Ra while it cannot be seen beyond {ital J}{sup +}=24{sup +}(25{sup {minus}}) in {sup 222}Th. These observations are consistent with Woods-Saxon-Bogolyubov cranking calculations which predict that the yrast band of {sup 222}Th will undergo a shape transition at {ital J}=24{h_bar}, in contrast to that of {sup 220}Ra which maintains its reflection asymmetry to higher spins.

  18. High-Spin States of {sup 84,85}Br: Mapping the Proton Sub-Shells towards {sup 78}Ni

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Deloncle, I.; Venkova, Ts.; Azaiez, F.; Buta, A.; Curien, D.; Dorvaux, O.; Duchene, G.; Gall, B. J. P.; Khalfallah, F.; Piqueras, I.; Rousseau, M.; Meyer, M.; Redon, N.; Stezowski, O.; Lucas, R.

    2008-05-12

    The {sup 84,85}Br nuclei have been produced as fission fragments in the fusion reaction {sup 18}O+{sup 208}Pb at 85 MeV bombarding energy and studied with the Euroball IV array. The high-spin states of the odd-odd {sup 84}Br nucleus have been identified for the first time. From angular correlation analysis, spin values have been assigned to most of the {sup 85}Br excited states up to 4 MeV. All observed states in {sup 84,85}Br can be described by various proton excitations involving at least the two sub-shells ({pi}f{sub 5/2} and {pi}p{sub 3/2}) located just above the Z = 28 shell closure.

  19. Spin Electronics

    DTIC Science & Technology

    2003-08-01

    spectroscopy laboratory including high pulse power capabilities (regenerative amplifiers and optical parametric amplifiers ) and broad spectral range ...The data identify narrow ranges of doping concentrations where spin lifetimes in semiconductors are enhanced by orders of magnitude, culminating in... dynamic measurements in the 10 to 100 picoseconds (ps) range . • A second program, which will come to fruition within one to two years, has the name

  20. Synthesis, Crystal Structure, and Thermal Decomposition of the Cobalt(II) Complex with 2-Picolinic Acid

    PubMed Central

    Li, Di

    2014-01-01

    The cobalt(II) complex of 2-picolinic acid (Hpic), namely, [Co(pic)2(H2O)2] · 2H2O, was synthesized with the reaction of cobalt acetate and 2-picolinic acid as the reactants by solid-solid reaction at room temperature. The composition and structure of the complex were characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, and thermogravimetry-differential scanning calorimetry (TG-DSC). The crystal structure of the complex belongs to monoclinic system and space group P2(1)/n, with cell parameters of a = 9.8468(7) Å, b = 5.2013(4) Å, c = 14.6041(15) Å, β = 111.745(6)°, V = 747.96(11) Å3, Z = 2, Dc = 1.666 g cm−3, R1 = 0.0297, and wR2 = 0.0831. In the title complex, the Co(II) ion is six-coordinated by two pyridine N atoms and two carboxyl O atoms from two 2-picolinic acid anions, and two O atoms from two H2O molecules, and forming a slightly distorted octahedral geometry. The thermal decomposition processes of the complex under nitrogen include dehydration and pyrolysis of the ligand, and the final residue is cobalt oxalate at about 450°C. PMID:24578654

  1. Photoinduced hydrogen evolution with new tetradentate cobalt(ii) complexes based on the TPMA ligand.

    PubMed

    Natali, Mirco; Badetti, Elena; Deponti, Elisa; Gamberoni, Marta; Scaramuzzo, Francesca A; Sartorel, Andrea; Zonta, Cristiano

    2016-10-07

    Hydrogen production from water splitting is nowadays recognized as a target, fundamental reaction for the production of clean fuels. Indeed, tremendous efforts have been devoted towards the research of suitable catalysts capable of performing this reaction. With respect to heterogeneous systems, molecular catalysts such as metal complexes are amenable to chemical functionalization in order to fine tune the catalytic properties. In this paper a new class of tris(2-pyridylmethyl)-amine (TPMA) cobalt(ii) complexes (CoL0-4) has been synthesized and employed as hydrogen evolving catalysts under photochemical conditions taking advantage of Ru(bpy)3(2+) (where bpy is 2,2'-bipyridine) as a light-harvesting sensitizer and ascorbic acid as a sacrificial electron donor. Tuning of the photocatalytic activity has been attempted through the introduction of different substituents at the catalyst periphery rather than through a direct chemical modification of the chelating TPMA ligand. The results show that CoL0-4 behave as competent hydrogen evolving catalysts (HECs), although the effects played by the different substituents on the catalysis are relatively modest. Possible reasons supporting the observed behavior as well as possible improvements of the aforementioned tuning approach are discussed.

  2. Analysis of cobalt(II) in 2-(5-cyanotetrazolato)pentaammine cobalt(III) perchlorate

    SciTech Connect

    Schumacher, R.J.; Brown, N.E.; Deutsch, E.A.

    1985-10-30

    A new method of analysis is described for cobalt(II) complexes in 2-(5-cyanotetrazolato)pentaammine cobalt(III) perchlorate. The color reagent is 2,2'-dipyridyl-2-pyridyl hydrazone (DPPH), which complexes with the Co(II) and is oxidized to a substitution inert Co(III) (DPPH)/sub 2/ complex. Interferences from other ions is not a problem because the complex is stable at pH 2 - where complexes formed between DPPH and other ions are not stable. The usual air oxidant in this type of analysis has been replaced with ammonium peroxydisulfate improving both the precision and accuracy. The Sandell sensitivity is 0.0015 ..mu..g Co(II)/cm/sup 2/. The system obeys Beer's Law up to 4 ..mu..g in Co(II)mL of solution and has a molar absorptivity of 3.9 x 10/sup 4/ L/mole cm at 514 nm. The procedure was used to determine the degree of decomposition in samples that had undergone partial thermal decomposition. 11 refs., 4 figs., 6 tabs.

  3. The fabrication of highly uniform ZnO/CdS core/shell structures using a spin-coating-based successive ion layer adsorption and reaction method.

    PubMed

    Joo, Jinmyoung; Kim, Darae; Yun, Dong-Jin; Jun, Hwichan; Rhee, Shi-Woo; Lee, Jae Sung; Yong, Kijung; Kim, Sungjee; Jeon, Sangmin

    2010-08-13

    We developed a successive ion layer adsorption and reaction method based on spin-coating (spin-SILAR) and applied the method to the fabrication of highly uniform ZnO/CdS core/shell nanowire arrays. Because the adsorption, reaction, and rinsing steps occur simultaneously during spin-coating, the spin-SILAR method does not require rinsing steps between the alternating ion adsorption steps, making the growth process simpler and faster than conventional SILAR methods based on dip-coating (dip-SILAR). The ZnO/CdS core/shell nanowire arrays prepared by spin-SILAR had a denser and more uniform structure than those prepared by dip-SILAR, resulting in the higher power efficiency for use in photoelectrochemical cells.

  4. Long-range and high-speed electronic spin-transport at a GaAs/AlGaAs semiconductor interface

    PubMed Central

    Nádvorník, L.; Němec, P.; Janda, T.; Olejník, K.; Novák, V.; Skoromets, V.; Němec, H.; Kužel, P.; Trojánek, F.; Jungwirth, T.; Wunderlich, J.

    2016-01-01

    Spin-valves or spin-transistors in magnetic memories and logic elements are examples of structures whose functionality depends crucially on the length and time-scales at which spin-information is transferred through the device. In our work we employ spatially resolved optical pump-and-probe technique to investigate these fundamental spin-transport parameters in a model semiconductor system. We demonstrate that in an undoped GaAs/AlGaAs layer, spins are detected at distances reaching more than ten microns at times as short as nanoseconds. We have achieved this unprecedented combination of long-range and high-speed electronic spin-transport by simultaneously suppressing mechanisms that limit the spin life-time and the mobility of carriers. By exploring a series of structures we demonstrate that the GaAs/AlGaAs interface can provide superior spin-transport characteristics whether deposited directly on the substrate or embedded in complex semiconductor heterostructures. We confirm our conclusions by complementing the optical experiments with dc and terahertz photo-conductivity measurements. PMID:26980667

  5. Method for estimating spin-spin interactions from magnetization curves

    NASA Astrophysics Data System (ADS)

    Tamura, Ryo; Hukushima, Koji

    2017-02-01

    We develop a method to estimate the spin-spin interactions in the Hamiltonian from the observed magnetization curve by machine learning based on Bayesian inference. In our method, plausible spin-spin interactions are determined by maximizing the posterior distribution, which is the conditional probability of the spin-spin interactions in the Hamiltonian for a given magnetization curve with observation noise. The conditional probability is obtained with the Markov chain Monte Carlo simulations combined with an exchange Monte Carlo method. The efficiency of our method is tested using synthetic magnetization curve data, and the results show that spin-spin interactions are estimated with a high accuracy. In particular, the relevant terms of the spin-spin interactions are successfully selected from the redundant interaction candidates by the l1 regularization in the prior distribution.

  6. “Nodal Gap” induced by the incommensurate diagonal spin density modulation in underdoped high- Tc superconductors

    DOE PAGES

    Zhou, Tao; Gao, Yi; Zhu, Jian -Xin

    2015-03-07

    Recenmore » tly it was revealed that the whole Fermi surface is fully gapped for several families of underdoped cuprates. The existence of the finite energy gap along the d-wave nodal lines (nodal gap) contrasts the common understanding of the d-wave pairing symmetry, which challenges the present theories for the high-Tcsuperconductors. Here we propose that the incommensurate diagonal spin-density-wave order can account for the above experimental observation. The Fermi surface and the local density of states are also studied. Our results are in good agreement with many important experiments in high-Tcsuperconductors.« less

  7. Evidence for single particle structure of high spin states in [sup 144]Pm and [sup 145]Pm

    SciTech Connect

    Glasmacher, T.; Caussyn, D.D.; Cottle, P.D.; Holcomb, J.W.; Johnson, T.D.; Kemper, K.W.; Kennedy, M.A.; Womble, P.C. )

    1993-06-01

    Excited states of the [ital Z]=61 isotopes [sup 144]Pm[sub 83] and [sup 154]Pm[sub 84] have been studied in the [sup 19]F+[sup 130]Te reaction at a beam energy of 85 MeV. Gamma-ray and conversion electron spectroscopy were used to establish the high spin states of [sup 144]Pm up to spin 20[h bar] and to extend the level spectrum of [sup 145]Pm up to a tentative spin of 33/2[h bar]. Empirical shell model calculations in a configuration space truncated to the [pi]1[ital h][sub 11/2], [pi]1[ital g][sub 7/2][sup [minus]1], and [pi]2[ital d][sub 5/2][sup [minus]1] protons and the [nu]2[ital f][sub 7/2] neutron outside the [sup 146]Gd core reproduce the observed energy levels in good agreement with the experimental results. ([pi][ital h][sub 11/2])[sup 2] configurations are suggested in an [ital N]=83 isotone for [ital Z][lt]64.

  8. Perturbational treatment of spin-orbit coupling for generally applicable high-level multi-reference methods

    SciTech Connect

    Mai, Sebastian; Marquetand, Philipp; González, Leticia; Müller, Thomas; Plasser, Felix; Lischka, Hans

    2014-08-21

    An efficient perturbational treatment of spin-orbit coupling within the framework of high-level multi-reference techniques has been implemented in the most recent version of the COLUMBUS quantum chemistry package, extending the existing fully variational two-component (2c) multi-reference configuration interaction singles and doubles (MRCISD) method. The proposed scheme follows related implementations of quasi-degenerate perturbation theory (QDPT) model space techniques. Our model space is built either from uncontracted, large-scale scalar relativistic MRCISD wavefunctions or based on the scalar-relativistic solutions of the linear-response-theory-based multi-configurational averaged quadratic coupled cluster method (LRT-MRAQCC). The latter approach allows for a consistent, approximatively size-consistent and size-extensive treatment of spin-orbit coupling. The approach is described in detail and compared to a number of related techniques. The inherent accuracy of the QDPT approach is validated by comparing cuts of the potential energy surfaces of acrolein and its S, Se, and Te analoga with the corresponding data obtained from matching fully variational spin-orbit MRCISD calculations. The conceptual availability of approximate analytic gradients with respect to geometrical displacements is an attractive feature of the 2c-QDPT-MRCISD and 2c-QDPT-LRT-MRAQCC methods for structure optimization and ab inito molecular dynamics simulations.

  9. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    SciTech Connect

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-06-03

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whose primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y

  10. NMRbot: Python scripts enable high-throughput data collection on current Bruker BioSpin NMR spectrometers.

    PubMed

    Clos, Lawrence J; Jofre, M Fransisca; Ellinger, James J; Westler, William M; Markley, John L

    2013-06-01

    To facilitate the high-throughput acquisition of nuclear magnetic resonance (NMR) experimental data on large sets of samples, we have developed a simple and straightforward automated methodology that capitalizes on recent advances in Bruker BioSpin NMR spectrometer hardware and software. Given the daunting challenge for non-NMR experts to collect quality spectra, our goal was to increase user accessibility, provide customized functionality, and improve the consistency and reliability of resultant data. This methodology, NMRbot, is encoded in a set of scripts written in the Python programming language accessible within the Bruker BioSpin TopSpin™ software. NMRbot improves automated data acquisition and offers novel tools for use in optimizing experimental parameters on the fly. This automated procedure has been successfully implemented for investigations in metabolomics, small-molecule library profiling, and protein-ligand titrations on four Bruker BioSpin NMR spectrometers at the National Magnetic Resonance Facility at Madison. The investigators reported benefits from ease of setup, improved spectral quality, convenient customizations, and overall time savings.

  11. Transition from collective to noncollective rotation at high spin in N approx. = 87 nuclei

    SciTech Connect

    Baktash, C.

    1982-01-01

    The systematics of the (E2) ..gamma.. ray transition energies and the available lifetime data are used to characterize the excitation modes of the light rare-earth nuclei (N greater than or equal to 82) at different spins. The results, which include our recently obtained data on /sup 149/Gd, /sup 154/Ho, /sup 155/Er, /sup 157/Yb and /sup 158/Yb nuclei, indicate that, at low spins, the nuclear excitation mode (shapes) change from single-particle excitations (weakly oblate) in N less than or equal to 85 nuclei to quasi-vibrational (soft triaxial) in N = 86, weakly rotational (prolate) in N = 87, and rotational (prolate) in the N greater than or equal to 88 systems. At higher angular momenta, all these nuclei show a general tendency to traverse the (epsilon,..gamma..) plane towards the oblate axis, and to eventually adopt the aligned coupling mode of excitation.

  12. Magic radio-frequency dressing of nuclear spins in high-accuracy optical clocks.

    PubMed

    Zanon-Willette, Thomas; de Clercq, Emeric; Arimondo, Ennio

    2012-11-30

    A Zeeman-insensitive optical clock atomic transition is engineered when nuclear spins are dressed by a nonresonant radio-frequency field. For fermionic species as (87)Sr, (171)Yb, and (199)Hg, particular ratios between the radio-frequency driving amplitude and frequency lead to "magic" magnetic values where a net cancelation of the Zeeman clock shift and a complete reduction of first-order magnetic variations are produced within a relative uncertainty below the 10(-18) level. An Autler-Townes continued fraction describing a semiclassical radio-frequency dressed spin is numerically computed and compared to an analytical quantum description including higher-order magnetic field corrections to the dressed energies.

  13. Confirmation of gravitationally induced attitude drift of spinning satellite Ajisai with Graz high repetition rate SLR data

    NASA Astrophysics Data System (ADS)

    Kucharski, Daniel; Kirchner, Georg; Otsubo, Toshimichi; Lim, Hyung-Chul; Bennett, James; Koidl, Franz; Kim, Young-Rok; Hwang, Joo-Yeon

    2016-02-01

    The high repetition rate Satellite Laser Ranging system Graz delivers the millimeter precision range measurements to the corner cube reflector panels of Ajisai. The analysis of 4599 passes measured from October 2003 until November 2014 reveals the secular precession and nutation of Ajisai spin axis due to the gravitational forces as predicted by Kubo (1987) with the periods of 35.6 years and 116.5 days respectively. The observed precession cone is oriented at RA = 88.9°, Dec = -88.85° (J2000) and has a radius of 1.08°. The radius of the nutation cone increases from 1.32° to 1.57° over the 11 years of the measurements. We also detect a draconitic wobbling of Ajisai orientation due to the 'motion' of the Sun about the satellite's orbit. The observed spin period of Ajisai increases exponentially over the investigated time span according to the trend function: T = 1.492277·exp(0.0148388·Y) [s], where Y is in years since launch (1986.6133), RMS = 0.412 ms. The physical simulation model fitted to the observed spin parameters proves a very low interaction between Ajisai and the Earth's magnetic field, what assures that the satellite's angular momentum vector will remain in the vicinity of the south celestial pole for the coming decades. The developed empirical model of the spin axis orientation can improve the accuracy of the range determination between the ground SLR systems and the satellite's center-of-mass (Kucharski et al., 2015) and enable the accurate attitude prediction of Ajisai for the laser time-transfer experiments (Kunimori et al., 1992).

  14. Point contact Andreev reflection and the measurement of spin polarization: high fields and novel materials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Stamenov, Plamen; Borisov, Kiril

    2016-10-01

    Point Contact Andreev Reflection (PCAR) is one of the few available methods for the determination of the Fermi level spin polarisation in metals and degenerate semiconductors. It has traditionally been applied at fixed (liquid He) temperatures, using pure niobium as the superconductor, and at essentially zero applied magnetic fields, all of which limit the amount of information that it can provide - i.e. do not allow for the extraction of the sign of the spin polarisation and make the assignment of the transport regime to ballistic or diffusive almost impossible. Here a series of experiments is described, aimed at the expansion of this parameter space to higher magnetic fields and to higher temperatures. These require redesigned experimental setups and the use of higher performance superconductors. Demonstrations are described of the determination of the sign of the spin polarisation, at fields of more than 5 Tesla using a low-Z superconductor, as well as operations beyond 9.2 K. Doubts about the practical reliability of the PCAR technique are dispersed using systematic series of samples - the heavy rare-earths and comparisons with alternatives, such as spin-polarised field emission, photo-emission and Tedrow-Meservey tunnelling. The specific material examples presented include 3d-metals, order-disorder transition alloys and zero-moment half-metals - Fe, FeAl and MnRuGa, alternative low-Z and high-Z superconductors - MgB2 and NbTi, and magnetic topological insulators, such as Cr- and V-doped (Bi1-xSbx)2Te3.

  15. A revolutionary rotatable electron energy analyzer for advanced high-resolution spin-polarized photoemission studies. Final Report

    SciTech Connect

    Waddill, G. D.; Willis, R. F.

    1999-10-01

    This report details the construction and testing of a unique analyzer for spin-polarized photoemission studies of magnetic materials. This report details the progress of this project for the period from 9/1/96 through 8/31/99. Progress can be divided into two distinct areas. These are the fabrication, construction, and initial testing of the instrumentation, and the concurrent program of preliminary investigations into materials and experiments appropriate for future studies using the instrumentation developed. The analyzer complete with special input electron optics and Mott detector has been assembled in a special design UHV chamber equipped with all the capabilities needed to perform the described programs of research. These include a sophisticated five motorized axis sample manipulator with low and high temperature capability and rapid temperature cycling (acquired in collaboration with Dr. J.G. Tobin of LLNL), vacuum leak detection and gauging, in situ thin film growth instrumentation, and sample cleaning and magnetizing capabilities, The initial testing of the analyzer has been completed with successful data acquisition using both the multichannel detector mode, and spin-dependent using the Mott detector channeltrons. The data collected using the Mott detector were not truly spin dependent (see below), but demonstrate the operation of the lens and detector design. Acquisition of truly spin-dependent data await use of the EPU. Preliminary indications suggest that the analyzer performs at or above the original design parameters. In the second area of progress, we have conducted a number of preliminary studies toward the ends of identifying appropriate initial systems for investigation, and to further explore new experiments that the new instrumentation will help to pioneer. More detailed descriptions of all of these advances are given.

  16. On-demand superradiant conversion of atomic spin gratings into single photons with high efficiency.

    PubMed

    Black, Adam T; Thompson, James K; Vuletić, Vladan

    2005-09-23

    We create quantized spin gratings by single-photon detection and convert them on demand into photons with retrieval efficiencies exceeding 40% (80%) for single (a few) quanta. We show that the collective conversion process, proceeding via superradiant emission into a moderate-finesse optical resonator, requires phase matching. The storage time of 3 micros in the cold-atom sample, as well as the peak retrieval efficiency, are likely limited by Doppler decoherence of the entangled state.

  17. High-Fidelity Microwave Control of Single-Atom Spin Qubits in Silicon

    DTIC Science & Technology

    2014-07-08

    measurement of the first qubit. The existence of these entangled states are a unique feature of quantum mechanics that has no classical analogue. The degree...16. SECURITY CLASSIFICATION OF: As classical computers begin to reach their fundamental performance limits, quantum computers will be an invaluable...microwave control of single-atom spin qubits in silicon Report Title As classical computers begin to reach their fundamental performance limits, quantum

  18. Finite violations of a Bell inequality for high spin: An optical realization

    SciTech Connect

    Gerry, Christopher C.; Albert, Jaroslav

    2005-10-15

    Some years ago Peres [Phys. Rev. A 46, 4413 (1992)] described a gedanken experiment for a pair of spatially spin j particles in a singlet state and showed using with a dichotomic observable (essentially a parity operator) that Bell's theorem in the form of the Clauser-Home-Shimony-Holt (CHSH) inequality is violated by a constant amount (24%) in the limit j{yields}{infinity}. In this paper we present a scheme for an optical realization of a state that is very close to the spin-j singlet state using two traveling-wave modes of the quantized field using a 50:50 beam splitter with an input number state. A near-singlet states comes about because the binomial output state of the beam splitter can be written as a sum in terms of states in the form vertical bar j,m>{sub 1}x vertical bar j,-m>{sub 2}, each state being associated with a Holstein-Primakoff realization of the su(2) spin algebra in terms of the Bose operators of each of the field modes, where j=N/2, N being the number of photons passing through the beam splitter. The binomial state can violate the CHSH inequality to a greater degree than does the singlet state.

  19. An overview of spin physics

    SciTech Connect

    Prescott, C.Y.

    1991-07-01

    Spin physics is playing an increasingly important role in high energy experiments and theory. This review looks at selected topics in high energy spin physics that were discussed at the 9th International Symposium on High Energy Spin Physics at Bonn in September 1990.

  20. One-dimensional spinon spin currents

    NASA Astrophysics Data System (ADS)

    Hirobe, Daichi; Sato, Masahiro; Kawamata, Takayuki; Shiomi, Yuki; Uchida, Ken-Ichi; Iguchi, Ryo; Koike, Yoji; Maekawa, Sadamichi; Saitoh, Eiji

    2017-01-01

    Quantum spin fluctuation in a low-dimensional or frustrated magnet breaks magnetic ordering while keeping spin correlation. Such fluctuation has been a central topic in magnetism because of its relevance to high-Tc superconductivity and topological states. However, utilizing such spin states has been quite difficult. In a one-dimensional spin-1/2 chain, a particle-like excitation called a spinon is known to be responsible for spin fluctuation in a paramagnetic state. Spinons behave as a Tomonaga-Luttinger liquid at low energy, and the spin system is often called a quantum spin chain. Here we show that a quantum spin chain generates and carries spin current, which is attributed to spinon spin current. This is demonstrated by observing an anisotropic negative spin Seebeck effect along the spin chains in Sr2CuO3. The results show that spin current can flow even in an atomic channel owing to long-range spin fluctuation.

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

    NASA Technical Reports Server (NTRS)

    Folenta, Dezi; Lebo, William

    1988-01-01

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

  2. Coexistence of magnetic fluctuations and superconductivity in the pnictide high temperature superconductor SmFeAsO1-xFx measured by muon spin rotation.

    PubMed

    Drew, A J; Pratt, F L; Lancaster, T; Blundell, S J; Baker, P J; Liu, R H; Wu, G; Chen, X H; Watanabe, I; Malik, V K; Dubroka, A; Kim, K W; Rössle, M; Bernhard, C

    2008-08-29

    Muon spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO1-xFx with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the vicinity of the superconducting transition which suggests that the spin fluctuations contribute to the formation of an unconventional superconducting state. An estimate of the in-plane penetration depth lambda ab(0)=190(5) nm was obtained, which confirms that the pnictide superconductors obey an Uemura-style relationship between Tc and lambda ab(0);(-2).

  3. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    SciTech Connect

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-07

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  4. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    NASA Astrophysics Data System (ADS)

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-01

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  5. 34. mu. s isomer at high spin in sup 212 Fr: Evidence for a many-particle octupole coupled state

    SciTech Connect

    Byrne, A.P.; Dracoulis, G.D.; Schiffer, K.J.; Davidson, P.M.; Kibedi, T.; Fabricius, B.; Baxter, A.M.; Stuchbery, A.E. Australian National University, G.P.O. Box 4, Canberra, Australian Capital Territory )

    1990-07-01

    A very high spin isomeric state with {tau}{sub {ital m}}=34(3) {mu}s has been observed at an excitation energy of 8.5 MeV in {sup 212}Fr. The experimental evidence favors an {ital E}3 assignment, with a very large {ital E}3 transition strength, {ital B}({ital E}3)=100(12){times}10{sup 3} {ital e}{sup 2}fm{sup 6}, to one of the {gamma} rays de-exciting the isomer. The observed properties are in very good agreement with the characteristics of a 34{sup +} state predicted by the multiparticle octupole vibration model.

  6. Design and commissioning of a high magnetic field muon spin relaxation spectrometer at the ISIS pulsed neutron and muon source.

    PubMed

    Lord, J S; McKenzie, I; Baker, P J; Blundell, S J; Cottrell, S P; Giblin, S R; Good, J; Hillier, A D; Holsman, B H; King, P J C; Lancaster, T; Mitchell, R; Nightingale, J B; Owczarkowski, M; Poli, S; Pratt, F L; Rhodes, N J; Scheuermann, R; Salman, Z

    2011-07-01

    The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.

  7. Design and commissioning of a high magnetic field muon spin relaxation spectrometer at the ISIS pulsed neutron and muon source

    SciTech Connect

    Lord, J. S.; McKenzie, I.; Baker, P. J.; Cottrell, S. P.; Giblin, S. R.; Hillier, A. D.; Holsman, B. H.; King, P. J. C.; Nightingale, J. B.; Pratt, F. L.; Rhodes, N. J.; Blundell, S. J.; Lancaster, T.; Good, J.; Mitchell, R.; Owczarkowski, M.; Poli, S.; Scheuermann, R.; Salman, Z.

    2011-07-15

    The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.

  8. In Vivo Detection of the Cyclic Osmoregulated Periplasmic Glucan of Ralstonia solanacearum by High-Resolution Magic Angle Spinning NMR

    NASA Astrophysics Data System (ADS)

    Wieruszeski, J.-M.; Bohin, A.; Bohin, J.-P.; Lippens, G.

    2001-07-01

    We investigate the mobility of the osmoregulated periplasmic glucans of Ralstonia solanacearum in the bacterial periplasm through the use of high-resolution (HR) NMR spectroscopy under static and magic angle spinning (MAS) conditions. Because the nature of periplasm is far from an isotropic aqueous solution, the molecules could be freely diffusing or rather associated to a periplasmic protein, a membrane protein, a lipid, or the peptidoglycan. HR MAS NMR spectroscopy leads to more reproducible results and allows the in vivo detection and characterization of the complex molecule.

  9. Despin of a Highly Spinning Object: Despin of the Army’s Unattended Expendable Jammer.

    DTIC Science & Technology

    1981-09-01

    PAGE BEFORE COMPLETING FORM I REPORT NUMBER 2. OVT ACCESSION NO. 3- RECIPIE .NT’S CATALOG NUMBER l(DL-TR- 1964 .4i’ 22 4. TITLE (~d S~blitl.) 5, TYPE...The results of camera and tachometer measurements of clespin are presented for a total of 12 tests with initial spins in the range of 50 to 57 rps. The...mined with a precision of one frame, or ±0.4 ins. The camera speed is known to an accuracy of within 10 frames/s. A tachometer was used to obtain

  10. High resolution 11B NMR of magnesium diboride using cryogenic magic angle spinning

    NASA Astrophysics Data System (ADS)

    Beckett, Peter; Denning, Mark S.; Heinmaa, Ivo; Dimri, Mukesh C.; Young, Edward A.; Stern, Raivo; Carravetta, Marina

    2012-09-01

    Static and magic-angle spinning 11B nuclear magnetic resonance (NMR) data at 4.7 T and 8.5 T have been obtained under cryogenic conditions on a diluted sample of magnesium diboride powder in the normal and superconducting state. The data provide accurate information on the magnetic shift and longitudinal relaxation time down to a temperature of 8 K, with a resolution improvement over the entire temperature range. The onset of superconductivity is unaffected by the sample rotation, as revealed by a steep variation of the magnetic shift just below the critical temperature.

  11. Population of high spin states in very heavy ion transfer reactions. The experimental evidence

    SciTech Connect

    Guidry, M.W.

    1985-01-01

    Transfer reactions have been studied for some time with light heavy ions such as oxygen. Although states of spin I approx.10 h are sometimes populated in such reactions, it is assumed that collective excitation is small, and the transferred particles are responsible for the angular momentum transfer. In this paper we will discuss a qualitatively different kind of transfer reaction using very heavy ions (A greater than or equal to 40). In these reactions the collective excitation in both the entrance and exit channels is strong, and there may be appreciable angular momentum transfer associated with inelastic excitation. 12 refs., 13 figs.

  12. Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

    SciTech Connect

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H. F.

    2015-11-24

    A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

  13. Side Moment Exerted by a Spinning, Coning, Highly Viscous Liquid Payload

    DTIC Science & Technology

    1989-12-01

    29 5 Boundary Layer Modifications to the Liquid Moment Coefficients ...... .. 30 6 Components of the Liquid Angular Momentum...logio Re for A = 4.5, r = 0.1. Comparison with Miller data.. . . 37 5 CLSM vG. loglo Re for A = 3, r = 0.1 ........................... 38 6 CLSM vs...that = rý[, - (eK_/y)i] ( 5 ) 4 y~+ KýV (6) where * ý is the projectile spin rate relative to an inertial frame; * T = r the ratio of the precessional rate

  14. Inelastic Neutron Scattering Studies of High-Energy Spin Excitations in Superconducting BaFe1.9Ni0.1As2

    NASA Astrophysics Data System (ADS)

    Liu, Mengshu; Abernathy, Douglas; Zhao, Jun; Wang, Meng; Zhang, Chenglin; Wang, Miaoyin; Dai, Pengcheng

    2010-03-01

    Understanding how the spin fluctuations evolve with doping in iron pnictide superconductors is important because spin fluctuations may mediate electron pairing for superconductivity in these materials. Upon doping, the spin fluctuation persists long after the long-range antiferromagnetism is destroyed. More importantly, spin excitations are coupled to superconductivity in the appearance of a neutron magnetic resonance and a superconductivity-induced spin gap. However, all current neutron scattering results in iron based superconductors are confined to low energy excitations except for the ``11'' FeTe1-xSex system, which shows incommensurate excitations that are not found in other iron pnictide systems. Therefore, how the spin waves in parent compounds of the ``122'' (AFe2As2, A = Ca, Sr, Ba) system will evolve when the system becomes an optimal superconductor is still an open question. We use time-of-flight spectroscopy to determine S (Q,φ) at energy regions not accessed before. We compare spin fluctuations of iron arsenide superconductors with those of high-Tc copper oxides and discuss their role in the superconductivity of these materials.

  15. Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces.

    PubMed

    Lesne, E; Fu, Yu; Oyarzun, S; Rojas-Sánchez, J C; Vaz, D C; Naganuma, H; Sicoli, G; Attané, J-P; Jamet, M; Jacquet, E; George, J-M; Barthélémy, A; Jaffrès, H; Fert, A; Bibes, M; Vila, L

    2016-12-01

    The spin-orbit interaction couples the electrons' motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism-the Rashba effect-in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.

  16. 31-day study of cobalt(II) chloride ingestion in humans: pharmacokinetics and clinical effects.

    PubMed

    Finley, Brent L; Unice, Kenneth M; Kerger, Brent D; Otani, Joanne M; Paustenbach, Dennis J; Galbraith, David A; Tvermoes, Brooke E

    2013-01-01

    The United Kingdom Expert Group on Vitamins and Minerals concluded that ingesting cobalt (Co)-containing supplements up to 1400 μg Co/d is unlikely to produce adverse health effects. However, the associated blood Co concentrations and safety of Co-containing dietary supplements have not been fully characterized. Thus, blood Co kinetics and a toxicological assessment of hematological and biochemical parameters were evaluated following Co dietary supplementation in 5 male and 5 female volunteers who ingested approximately 1000 μg Co/d (10-19 μg Co/kg-d) as cobalt(II) chloride for a period of 31 d. Supplement intake was not associated with significant overt adverse events, alterations in clinical chemistries including blood counts and indicators of thyroid, cardiac, liver, or kidney functions, or metal sensitization. A non-clinically significant (<5%) increase in hemoglobin, hematocrit, and red blood cell (RBC) counts were observed in males but not females 1 wk after dose termination. Mean Co concentrations in whole blood/serum after 31 d of dosing were approximately two-fold higher in females (33/53 μg/L) than in males (16/21 μg/L). In general, steady-state concentrations of Co were achieved in whole blood and/or red blood cells (RBC) within 14-24 d. Temporal patterns of whole blood and serum Co concentrations indicated metal sequestration in RBC accompanied by slower whole blood clearance compared to serum. Data also indicated that peak whole blood Co concentrations up to 91.4 μg/L were not associated with clinically significant changes in clinical chemistries. In addition, Co blood concentrations and systemic uptake via ingestion were generally higher in females.

  17. Modelling the high-mass accretion rate spectra of GX 339-4: black hole spin from reflection?

    NASA Astrophysics Data System (ADS)

    Kolehmainen, Mari; Done, Chris; Díaz Trigo, María

    2011-09-01

    We extract all the XMM-Newton European Photon Imaging Camera (EPIC) pn burst mode spectra of GX 339-4, together with simultaneous/contemporaneous RXTE data. These include three disc-dominated and two soft intermediate spectra, and the combination of broad bandpass/moderate spectral resolution gives some of the best data on these bright soft states in black hole binaries. The disc-dominated spectra span a factor of 3 in luminosity, and all show that the disc emission is broader than the simplest multicolour disc model. This is consistent with the expected relativistic smearing and changing colour temperature correction produced by atomic features in the newest disc models. However, these models do not match the data at the 5 per cent level as the predicted atomic features are not present in the data, perhaps indicating that irradiation is important even when the high-energy tail is weak. Whatever the reason, this means that the data have smaller errors than the best physical disc models, forcing use of more phenomenological models for the disc emission. We use these for the soft intermediate state data, where previous analysis using a simple disc continuum found an extremely broad residual, identified as the red wing of the iron line from reflection around a highly spinning black hole. However, the iron line energy is close to where the disc and tail have equal fluxes, so using a broader disc continuum changes the residual 'iron line' profile dramatically. With a broader disc continuum model, the inferred line is formed outside of 30Rg, so it cannot constrain black hole spin. We caution that a robust determination of black hole spin from the iron line profile is very difficult where the disc makes a significant contribution at the iron line energy, i.e. in most bright black hole states.

  18. EPR and Mössbauer Spectroscopy, and DFT Analysis of a High-Spin FeIV-oxo Complex

    PubMed Central

    Gupta, Rupal; Lacy, David C.; Bominaar, Emile L.; Borovik, Andrew. S.; Hendrich, Michael P.

    2013-01-01

    The kinetically competent oxidant in non-heme iron enzymes is a high-spin FeIV-oxo species, which are not as well characterized as the intermediate-spin species of heme systems. The present work gives a detailed characterization of the structurally similar [FeIVH3buea(O)]-, [FeIIIH3buea(O)]2- and [FeIIIH3buea(OH)]- (H3buea = tris[(N'-tert-butylureaylato)-N-ethylene]aminato) complexes using Mössbauer and dual-frequency/dual-mode electron paramagnetic resonance (EPR) spectroscopies. The [FeIVH3buea(O)]- complex has a high-spin (S = 2) configuration imposed from the C3-symmetric ligand. EPR spectroscopy of the [FeIVH3buea(O)]- complex is the first documented example of an EPR signal from an FeIV-oxo complex, demonstrating the ability to detect and quantify FeIV species with EPR spectroscopy. Quantitative simulations allowed determination of the zero-field parameter, D = +4.7 cm-1, and the species concentration. Density functional theory calculations of the zero-field parameter are found to be in agreement with the experimental value and indicate the major contribution to the D-value is from spin–orbit coupling of the ground state with an excited S = 1 electronic configuration at 1.2 eV. 17O isotope enrichment experiments allowed a determination of the hyperfine constant 170Az = 10 MHz for [FeIVH3buea(O)]- and 170Ay = 8 MHz, 170Az = 12 MHz for [FeIIIH3buea(OH)]-. The isotropic hyperfine constant (170Aiso = -16.8 MHz) was derived from the experimental value to allow a quantitative determination of the spin polarization (ρp = 0.56) of the oxo p-orbitals of the Fe-oxo bond in [FeIVH3buea(O)]-. This is the first experimental determination for non-heme complexes, and indicates significant covalency in the Fe-oxo bond. High-field Mössbauer spectroscopy gave an 57Fe Adip tensor of (+5.6, +5.3, -10.9) MHz and Aiso = -25.9 MHz for the [FeIVH3buea(O)]- complex, and DFT calculations are in agreement with the nuclear parameters of the complex. PMID:22574962

  19. Analytical high-order post-Newtonian expansions for spinning extreme mass ratio binaries

    NASA Astrophysics Data System (ADS)

    Kavanagh, Chris; Ottewill, Adrian C.; Wardell, Barry

    2016-06-01

    We present an analytic computation of Detweiler's redshift invariant for a point mass in a circular orbit around a Kerr black hole, giving results up to 8.5 post-Newtonian order while making no assumptions on the magnitude of the spin of the black hole. Our calculation is based on the functional series method of Mano, Suzuki and Takasugi, and employs a rigorous mode-sum regularization prescription based on the Detweiler-Whiting singular-regular decomposition. The approximations used in our approach are minimal; we use the standard self-force expansion to linear order in the mass ratio, and the standard post-Newtonian expansion in the separation of the binary. A key advantage of this approach is that it produces expressions that include contributions at all orders in the spin of the Kerr black hole. While this work applies the method to the specific case of Detweiler's redshift invariant, it can be readily extended to other gauge-invariant quantities and to higher post-Newtonian orders.

  20. Proton versus neutron excitations in the high-spin spectrum of 102Cd

    NASA Astrophysics Data System (ADS)

    Lieb, K. P.; Kast, D.; Jungclaus, A.; Johnstone, I. P.; de Angelis, G.; Bizzeti, P. G.; Dewald, A.; Fahlander, C.; Górska, M.; Grawe, H.; Peusquens, R.; de Poli, M.; Tiesler, H.

    The structures of the light Cd (Z = 48) isotopes are dominated by two g9/2 proton holes and several neutrons in the d5/2, g7/2, s1/2, d3/2 and/or h11/2 orbits1-5 Up to spin 8+, the even-A isotopes 100,102Cd exhibit two well separated "families" of either proton-hole or neutron-particle character, which communicate by extremely retarded E2 transitions, as small as 10-2 Wu. This implies that the configurations have rather good proton and neutron seniorities. Indeed, the magnetic dipole and electric quadrupole moments of the isomeric {8^+_1} state in 102Cd prove its π-2(99/2)proton-hole structure1 At higher spins, both proton-hole and neutron-particle pairs are broken, giving rise to magnetic dipole bands. It was the aim of the present lifetime measurements to determine absolute Ml and E2 transition strengths in this nucleus in order to test the predictions of two shell model calculations…

  1. Slow spin relaxation in dipolar spin ice.

    NASA Astrophysics Data System (ADS)

    Orendac, Martin; Sedlakova, Lucia; Orendacova, Alzbeta; Vrabel, Peter; Feher, Alexander; Pajerowski, Daniel M.; Cohen, Justin D.; Meisel, Mark W.; Shirai, Masae; Bramwell, Steven T.

    2009-03-01

    Spin relaxation in dipolar spin ice Dy2Ti2O7 and Ho2Ti2O7 was investigated using the magnetocaloric effect and susceptibility. The magnetocaloric behavior of Dy2Ti2O7 at temperatures where the orientation of spins is governed by ``ice rules`` (T < Tice) revealed thermally activated relaxation; however, the resulting temperature dependence of the relaxation time is more complicated than anticipated by a mere extrapolation of the corresponding high temperature data [1]. A susceptibility study of Ho2Ti2O7 was performed at T > Tice and in high magnetic fields, and the results suggest a slow relaxation of spins analogous to the behavior reported in a highly polarized cooperative paramagnet [2]. [1] J. Snyder et al., Phys. Rev. Lett. 91 (2003) 107201. [2] B. G. Ueland et al., Phys. Rev. Lett. 96 (2006) 027216.

  2. Measurements of nuclear spin dynamics by spin-noise spectroscopy

    SciTech Connect

    Ryzhov, I. I.; Poltavtsev, S. V.; Kozlov, G. G.; Zapasskii, V. S.; Kavokin, K. V.; Glazov, M. M.; Vladimirova, M.; Scalbert, D.; Cronenberger, S.; Lemaître, A.; Bloch, J.

    2015-06-15

    We exploit the potential of the spin noise spectroscopy (SNS) for studies of nuclear spin dynamics in n-GaAs. The SNS experiments were performed on bulk n-type GaAs layers embedded into a high-finesse microcavity at negative detuning. In our experiments, nuclear spin polarisation initially prepared by optical pumping is monitored in real time via a shift of the peak position in the electron spin noise spectrum. We demonstrate that this shift is a direct measure of the Overhauser field acting on the electron spin. The dynamics of nuclear spin is shown to be strongly dependent on the electron concentration.

  3. Perpendicular Magnetic Anisotropy and High Spin Polarization in Tetragonal Fe4N /BiFeO3 Heterostructures

    NASA Astrophysics Data System (ADS)

    Yin, Li; Mi, Wenbo; Wang, Xiaocha

    2016-12-01

    The tetragonal Fe4N /BiFeO3(001 ) heterostructures aimed at simultaneously gaining the perpendicular magnetic anisotropy (PMA) and high spin polarization have been investigated by the first-principles method. It is found that Fe4N with FeAFeB termination is better for achieving interfacial and inner PMA simultaneously than (FeB)2N termination. When the positions of interfacial FeA and FeB relative to Fe in BiFeO3 are changed, the PMA in Fe4N transforms into the in-plane magnetic anisotropy. Especially, PMA in Fe4N near the heterointerfaces depends on the direction of ferroelectric polarization in BiFeO3 . Finally, the interfacial and inner PMA of Fe4N along with high spin polarization appear in the stable FeAFeB/Fe -O2 case owing to the 3 d -3 d orbital hybridization. These results provide the opportunities for developing multifunctional spintronic devices.

  4. High-frequency, spin-label EPR of nonaxial lipid ordering and motion in cholesterol-containing membranes.

    PubMed

    Gaffney, B J; Marsh, D

    1998-10-27

    The EPR spectra of spin-labeled lipid chains in fully hydrated bilayer membranes of dimyristoyl phosphatidylcholine containing 40 mol % of cholesterol have been studied in the liquid-ordered phase at a microwave radiation frequency of 94 GHz. At such high field strengths, the spectra should be optimally sensitive to lateral chain ordering that is expected in the formation of in-plane domains. The high-field EPR spectra from random dispersions of the cholesterol-containing membranes display very little axial averaging of the nitroxide g-tensor anisotropy for lipids spin labeled toward the carboxyl end of the sn-2 chain (down to the 8-C atom). For these positions of labeling, anisotropic 14N-hyperfine splittings are resolved in the gzz and gyy regions of the nonaxial EPR spectra. For positions of labeling further down the lipid chain, toward the terminal methyl group, the axial averaging of the spectral features systematically increases and is complete at the 14-C atom position. Concomitantly, the time-averaged element of the 14N-hyperfine tensor decreases, indicating that the axial rotation at the terminal methyl end of the chains arises from correlated torsional motions about the bonds of the chain backbone, the dynamics of which also give rise to a differential line broadening of the 14N-hyperfine manifolds in the gzz region of the spectrum. These results provide an indication of the way in which lateral ordering of lipid chains in membranes is induced by cholesterol.

  5. An improved numerical method to compute neutron/gamma deexcitation cascades starting from a high spin state

    DOE PAGES

    Regnier, D.; Litaize, O.; Serot, O.

    2015-12-23

    Numerous nuclear processes involve the deexcitation of a compound nucleus through the emission of several neutrons, gamma-rays and/or conversion electrons. The characteristics of such a deexcitation are commonly derived from a total statistical framework often called “Hauser–Feshbach” method. In this work, we highlight a numerical limitation of this kind of method in the case of the deexcitation of a high spin initial state. To circumvent this issue, an improved technique called the Fluctuating Structure Properties (FSP) method is presented. Two FSP algorithms are derived and benchmarked on the calculation of the total radiative width for a thermal neutron capture onmore » 238U. We compare the standard method with these FSP algorithms for the prediction of particle multiplicities in the deexcitation of a high spin level of 143Ba. The gamma multiplicity turns out to be very sensitive to the numerical method. The bias between the two techniques can reach 1.5 γγ/cascade. Lastly, the uncertainty of these calculations coming from the lack of knowledge on nuclear structure is estimated via the FSP method.« less

  6. An improved numerical method to compute neutron/gamma deexcitation cascades starting from a high spin state

    SciTech Connect

    Regnier, D.; Litaize, O.; Serot, O.

    2015-12-23

    Numerous nuclear processes involve the deexcitation of a compound nucleus through the emission of several neutrons, gamma-rays and/or conversion electrons. The characteristics of such a deexcitation are commonly derived from a total statistical framework often called “Hauser–Feshbach” method. In this work, we highlight a numerical limitation of this kind of method in the case of the deexcitation of a high spin initial state. To circumvent this issue, an improved technique called the Fluctuating Structure Properties (FSP) method is presented. Two FSP algorithms are derived and benchmarked on the calculation of the total radiative width for a thermal neutron capture on 238U. We compare the standard method with these FSP algorithms for the prediction of particle multiplicities in the deexcitation of a high spin level of 143Ba. The gamma multiplicity turns out to be very sensitive to the numerical method. The bias between the two techniques can reach 1.5 γγ/cascade. Lastly, the uncertainty of these calculations coming from the lack of knowledge on nuclear structure is estimated via the FSP method.

  7. High-field electron spin resonance spectroscopy study of GdFeAsO1-xFx superconductors

    NASA Astrophysics Data System (ADS)

    Alfonsov, A.; Murányi, F.; Kataev, V.; Lang, G.; Leps, N.; Wang, L.; Klingeler, R.; Kondrat, A.; Hess, C.; Wurmehl, S.; Köhler, A.; Behr, G.; Hampel, S.; Deutschmann, M.; Katrych, S.; Zhigadlo, N. D.; Bukowski, Z.; Karpinski, J.; Büchner, B.

    2011-03-01

    We report a detailed investigation of GdO1-xFxFeAs (x=0, 0.07, and 0.14) samples by means of high-field and high-frequency electron spin resonance (HF-ESR) together with measurements of thermodynamic and transport properties. The parent GdOFeAs compound exhibits Fe long-range magnetic order below 128K, whereas both doped samples do not show such order and are superconducting with Tc=20 K (x=0.07) and Tc=45 K (x=0.14). The Gd3+ HF-ESR reveals an appreciable exchange coupling between Gd and Fe moments, through which the static magnetic order is clearly seen in the parent compound. Owing to this coupling, HF-ESR can probe sensitively the evolution of the magnetism in the FeAs planes upon F doping. It is found that in both superconducting samples, where the Fe long-range order is absent, there are short-range, static on the ESR time scale magnetic correlations between Fe spins. Their occurrence on a large doping scale may be indicative of the ground states’ coexistence.

  8. Specific features of insulator-metal transitions under high pressure in crystals with spin crossovers of 3d ions in tetrahedral environment

    SciTech Connect

    Lobach, K. A. Ovchinnikov, S. G.; Ovchinnikova, T. M.

    2015-01-15

    For Mott insulators with tetrahedral environment, the effective Hubbard parameter U{sub eff} is obtained as a function of pressure. This function is not universal. For crystals with d{sup 5} configuration, the spin crossover suppresses electron correlations, while for d{sup 4} configurations, the parameter U{sub eff} increases after a spin crossover. For d{sup 2} and d{sup 7} configurations, U{sub eff} increases with pressure in the high-spin (HS) state and is saturated after the spin crossover. Characteristic features of the insulator-metal transition are considered as pressure increases; it is shown that there may exist cascades of several transitions for various configurations.

  9. Spectral shape deformation in inverse spin Hall voltage in Y{sub 3}Fe{sub 5}O{sub 12}|Pt bilayers at high microwave power levels

    SciTech Connect

    Lustikova, J. Shiomi, Y.; Handa, Y.; Saitoh, E.

    2015-02-21

    We report on the deformation of microwave absorption spectra and of the inverse spin Hall voltage signals in thin film bilayers of yttrium iron garnet (YIG) and platinum at high microwave power levels in a 9.45-GHz TE{sub 011} cavity. As the microwave power increases from 0.15 to 200 mW, the resonance field shifts to higher values, and the initially Lorentzian spectra of the microwave absorption intensity as well as the inverse spin Hall voltage signals become asymmetric. The contributions from opening of the magnetization precession cone and heating of YIG cannot well reproduce the data. Control measurements of inverse spin Hall voltages on thin-film YIG|Pt systems with a range of line widths underscore the role of spin-wave excitations in spectral deformation.

  10. Fabrication and characterization of high mobility spin-coated zinc oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Singh, Shaivalini; Chakrabarti, P.

    2012-10-01

    A ZnO based thin film transistor (TFT) with bottom-gate configuration and SiO2 as insulating layer has been fabricated and characterized. The ZnO thin film was prepared by spin coating the sol-gel solution on the p-type Si wafers. The optical and structural properties of ZnO films were investigated using UV measurements and scanning electron microscope (SEM). The result of UV-visible study confirms that the films have a good absorbance in UV region and relatively low absorbance in the visible region. The TFT exhibited an off-current of 2.5×10-7 A. The values of field effect channel mobility and on/off current ratio extracted for the device, measured 11 cm2/V.s and ~102 respectively. The value of threshold voltage was found to be 1.3 V.

  11. High-spin octupole yrast levels in {sup 216}Rn{sub 86}

    SciTech Connect

    Debray, M.E.; Davidson, J.; Davidson, M.; Kreiner, A. J.; Cardona, M. A.; Hojman, D.; Napoli, D.R.; De Angelis, G.; De Poli, M.; Gadea, A.; Lenzi, S.; Bazzacco, D.; Lunardi, S.; Rossi-Alvarez, C.; Ur, C.A.; Medina, N.

    2006-02-15

    The yrast level structure of {sup 216}Rn has been studied using in-beam spectroscopy {alpha}-{gamma}-{gamma} coincidence techniques through the {sup 208}Pb({sup 18}O, 2{alpha}2n) reaction in the 91-93 MeV energy range, using the 8{pi} GASP-ISIS spectrometer at Legnaro. The level scheme of {sup 216}Rn resulting from this study shows alternating parity bands only above a certain excitation energy. From this result, the lightest nucleus showing evidence of octupole collectivity at low spins is still {sup 216}Fr, thereby defining the lowest-mass corner for this kind of phenomenon as N{>=}129 and Z{>=}87.

  12. High resolution 11B NMR of MgB2 using cryogenic magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Stern, Raivo; Beckett, Peter; Denning, Mark S.; Heinmaa, Ivo; Dimri, Mukesh C.; Young, Edward A.; Carravetta, Marina

    2013-03-01

    Static and magic-angle spinning (MAS) 11B NMR data at 4.7 T and 8.5 T have been obtained under cryogenic conditions on a diluted sample of magnesium diboride powder in the normal and superconducting state. We demonstrate that MAS NMR is possible on type-II superconductors despite the sample rotation. The data provide accurate information on the magnetic shift variation and longitudinal relaxation data down to a temperature of 8 K, with a resolution improvement over the entire temperature range. The onset of superconductivity is unaffected by the sample rotation, as revealed by a steep variation of the magnetic shift just below the critical temperature. Appeared in JCP 137, 114201, http://dx.doi.org/10.1063/1.4751476

  13. High-spin states in {sup 92-96}Zr nuclei

    SciTech Connect

    Pantelica, D.; Stefan, I.Gh.; Nica, N.; Porquet, M.-G.; Deloncle, I.; Bauchet, A.; Wilson, A.

    2005-08-01

    The {sup 92-96}Zr nuclei were produced as fission fragments following the fusion reactions {sup 28}Si+{sup 176}Yb and {sup 31}P+{sup 176}Yb at 145 and 152 MeV bombarding energy, respectively. Prompt {gamma} rays emitted in the two reactions were detected with the EUROGAM II and EUROBALL IV arrays. Sequences of {gamma}-ray transitions observed in coincidence were newly assigned to {sup 93-96}Zr. The previously known level schemes have been extended to higher excitation energies and higher spins. The experimental results are discussed in the framework of shell-model calculations with {sup 88}Sr assumed to be an inert core and the valence protons and neutrons filling the {pi}(2p{sub 1/2},1g{sub 9/2}) and {nu}(2d{sub 5/2},3s{sub 1/2}) orbitals.

  14. Estimation of parameters involved in high angle-of-attack aerodynamic theory using spin flight test data

    NASA Technical Reports Server (NTRS)

    Taylor, L. W., Jr.; Pamadi, B. N.

    1983-01-01

    The difficulty in applying parameter estimation techniques to spinning airplanes is due in part to the unwieldy number of possible combinations of terms in the equations of motion, when the model structure is unknown. The combination of high angle of attack and high rotation rate results in aerodynamic functions which are quite complex. For wing dominated configurations it is advantageous to use aerodynamic theory to generate the model structure. In this way, the number of unknown parameters is reduced and the model accuracy may be increased. Under conditions for which the theory is inadequate, however, model accuracy may be reduced. Strip theory, for example, is incapable of predicting autorotative rolling moments indicated by wind tunnel tests at angles of attack exceeding 40 degrees. An improved aerodynamic theory would be necessary to successfully apply the technique advanced for such regions.

  15. Measurement of Br photofragment orientation and alignment from HBr photodissociation: Production of highly spin-polarized hydrogen atoms

    SciTech Connect

    Rakitzis, T. Peter; Samartzis, P.C.; Toomes, R.L.; Kitsopoulos, Theofanis N.

    2004-10-15

    The orientation and alignment of the {sup 2}P{sub 3/2} and {sup 2}P{sub 1/2} Br photofragments from the photodissociation of HBr is measured at 193 nm in terms of a{sub q}{sup (k)}(p) parameters, using slice imaging. The A {sup 1}{pi} state is excited almost exclusively, and the measured a{sub q}{sup (k)}(p) parameters and the spin-orbit branching ratio show that the dissociation proceeds predominantly via nonadiabatic transitions to the a {sup 3}{pi} and 1 {sup 3}{sigma}{sup +} states. Conservation of angular momentum shows that the electrons of the nascent H atom cofragments (recoiling parallel to the photolysis polarization) are highly spin polarized: about 100% for the Br({sup 2}P{sub 1/2}) channel, and 86% for the Br({sup 2}P{sub 3/2}) channel. A similar analysis is demonstrated for the photodissociation of HCl.

  16. High-spin states in /sup 201,203/At and the systematic behavior of Z = 85 isotopes

    SciTech Connect

    Dybdal, K.; Chapuran, T.; Fossan, D.B.; Piel, W.F. Jr.; Horn, D.; Warburton, E.K.

    1983-09-01

    A spectroscopic investigation of high-spin states in /sup 201,203/At was performed by means of the reactions /sup 192,194/Pt(/sup 14/N,5n)/sup 201,203/At with /sup 14/N energies between 85 and 100 MeV. In-beam measurements of ..gamma..-ray excitation functions, ..gamma..-..gamma.. coincidences, ..gamma..-ray angular distributions, and pulsed-beam-..gamma.. timing were made to determine the decay scheme, level energies, ..gamma..-ray multipolarities, spin-parity assignments, and isomeric lifetimes. The yrast and near-yrast level structures were established up to Japprox.(25/2), and several isomers with mean lifetimes around 20 ns were observed. The systematic trends of level energies of the odd-mass astatine (Z = 85) isotopes are discussed in terms of proton-particle configurations of /sup 211//sub 85/At/sub 126/ coupled to neutron-hole configurations of the corresponding even-mass lead isotones.

  17. Negative-parity high-spin states and a possible magnetic rotation band in 76 59 135Pr

    NASA Astrophysics Data System (ADS)

    Garg, Ritika; Kumar, S.; Saxena, Mansi; Goyal, Savi; Siwal, Davinder; Kalkal, Sunil; Verma, S.; Singh, R.; Pancholi, S. C.; Palit, R.; Choudhury, Deepika; Ghugre, S. S.; Mukherjee, G.; Kumar, R.; Singh, R. P.; Muralithar, S.; Bhowmik, R. K.; Mandal, S.

    2015-11-01

    Excited states in 135Pr have been investigated using the reaction 123Sb(16O,4 n )135Pr at an incident beam energy of 82 MeV. The partial level scheme has been established for negative-parity states with addition of new γ -ray transitions. The directional correlation and polarization measurements have been performed to assign spin parity for most of the reported γ -ray transitions. At high spin, a negative-parity dipole band (Δ I =1 ) has been reported along with the observation of new crossover E 2 transitions. Tilted Axis Cranking (TAC) calculations have been performed by considering a three-quasiparticle (3qp) configuration π (h11/2) 1⊗ν (h11/2) -2 and a five-quasiparticle (5qp) configuration π (h11/2) 1(g7/2) 2⊗ν (h11/2) -2 for the lower and upper parts of the band, respectively. The observed results are compared with the results of the theoretical (TAC) calculations.

  18. Highly optimized simulations on single- and multi-GPU systems of the 3D Ising spin glass model

    NASA Astrophysics Data System (ADS)

    Lulli, M.; Bernaschi, M.; Parisi, G.

    2015-11-01

    We present a highly optimized implementation of a Monte Carlo (MC) simulator for the three-dimensional Ising spin-glass model with bimodal disorder, i.e., the 3D Edwards-Anderson model running on CUDA enabled GPUs. Multi-GPU systems exchange data by means of the Message Passing Interface (MPI). The chosen MC dynamics is the classic Metropolis one, which is purely dissipative, since the aim was the study of the critical off-equilibrium relaxation of the system. We focused on the following issues: (i) the implementation of efficient memory access patterns for nearest neighbours in a cubic stencil and for lagged-Fibonacci-like pseudo-Random Numbers Generators (PRNGs); (ii) a novel implementation of the asynchronous multispin-coding Metropolis MC step allowing to store one spin per bit and (iii) a multi-GPU version based on a combination of MPI and CUDA streams. Cubic stencils and PRNGs are two subjects of very general interest because of their widespread use in many simulation codes.

  19. Probing multiferroicity and spin-spin interactions via angular dependent dielectric measurements on Y-doped HoMnO3 in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Vasic, R.; Zhou, H. D.; Brooks, J. S.; Wiebe, C. R.

    2007-05-01

    Dielectric measurements are used to characterize magnetic phase transitions in the doped ferroelectric oxides Ho1-xYxMnO3 (x=0.4). The focus of this experiment is on the effects of the magnetic field direction on the reentrant T-B-θ phase diagram below the Néel temperature. The Ho sublattice plays a major role in all magnetic phase transitions for Y doping (x =0.4), consistent with previous results (x=0,0.6,0.8). Two successive Mn spin rotations in the ab plane in the antiferromagnetic state are driven by the interaction with the Ho subsystem, although the Ho ordering peak in data is not pronounced. The dielectric response is a very sensitive probe for fine analysis of all aspects of spin-spin interactions in diluted Ho1-xYxMnO3. The magnetic field anisotropy study is an important step towards the understanding of magnetic and electric phase competition in the diluted 4f system by the nonmagnetic yttrium (Y) ion.

  20. Unusual high-spin Fe5 +-Ni3 + state and strong ferromagnetism in the mixed perovskite SrFe0.5Ni0.5O3

    NASA Astrophysics Data System (ADS)

    Fan, Fengren; Li, Zhengwei; Zhao, Zhen; Yang, Ke; Wu, Hua

    2016-12-01

    The charge-spin-orbital state plays a vital role in correlated oxides with mixed transition-metal elements, and it is often a matter of debate. Here, we address this issue for the newly synthesized unusual high-valence perovskite SrFe1 -xNixO3 , using an analysis of crystal-field level diagrams, density functional calculations, and Monte Carlo simulations. We have identified the formal high-spin Fe5 +(t2g 3, S =3 /2 ) and high-spin Ni3 +(t2g 5eg2 , S =3 /2 ) state for SrFe0.5Ni0.5O3 , rather than the previously suggested high-spin Fe4 +(t2g 3eg1, S =2 ) and low-spin Ni4 + (t2g 6, S =0 ) state. Moreover, our model and the present results well explain the observed small lattice variation of SrFe1 -xNixO3 (0 ≤x ≤0.5 ) and the above room temperature ferromagnetic order in SrFe0.5Ni0.5O3 regardless of a Fe-Ni atomic order or disorder.

  1. Spin-Orbit Coupling and Potential Energy Functions of Ar2(+) and Kr2(+) by High-Resolution Photoelectron Spectroscopy and ab Initio Quantum Chemistry.

    PubMed

    Mastalerz, R; Zehnder, O; Reiher, M; Merkt, F

    2012-10-09

    The dependence of the spin-orbit-coupling constant of the six low-lying electronic states of Ar2(+) and Kr2(+) on the internuclear distance R has been calculated ab initio. The spin-orbit-coupling constant varies by about 10% over the range of internuclear distances relevant for the interpretation of the high-resolution photoelectron spectra of Ar2 and Kr2 and can be accurately represented by a Morse-type function for the states of ungerade electronic symmetry and by an exponentially decreasing function for the states of gerade symmetry. The spin-orbit-coupling constant is larger than the asymptotic value (at R → ∞) for the gerade states and smaller for the ungerade states. The calculated R-dependent spin-orbit-coupling constants were used to derive a new set of potential energy functions for the low-lying electronic states of Ar2(+) and Kr2(+) and to quantify the errors resulting from the widely used approach consisting of approximating the spin-orbit-coupling constant by its asymptotic value. The effects of the R dependence on the potential energy functions of the six low-lying electronic states of the homonuclear rare-gas dimer ions are found to be very small for Ar2(+) (and by inference also for Ne2(+)) but significant for Kr2(+). The shifts arising in calculations of the potential energy functions from a neglect of the R dependence of the spin-orbit-coupling constant are the result of the interplay between the differences between the binding energies of the relevant (2)Π and (2)Σ(+) states, the magnitude of the spin-orbit-coupling constant, and the magnitude and sign of the deviations between the R-dependent spin-orbit-coupling constant and its asymptotic value at large internuclear distances.

  2. PREFACE: Spin Electronics

    NASA Astrophysics Data System (ADS)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  3. Spin-Rotation Hyperfine Splittings at Moderate to High J Values in Methanol

    NASA Astrophysics Data System (ADS)

    Xu, Li-Hong; Hougen, Jon T.; Belov, Sergey; Golubiatnikov, G. Yu; Lapinov, Alexander; Ilyushin, V.; Alekseev, E. A.; Mescheryakov, A. A.

    2015-06-01

    In this talk we present a possible explanation, based on torsionally mediated proton-spin-overall-rotation interaction operators, for the surprising observation in Nizhny Novgorod several years ago of doublets in some Lamb-dip sub-millimeter-wave transitions between torsion-rotation states of E symmetry in methanol. These observed doublet splittings, some as large as 70 kHz, were later confirmed by independent Lamb-dip measurements in Kharkov. In this talk we first show the observed J-dependence of the doublet splittings for two b-type Q branches (one from each laboratory), and then focus on our theoretical explanation. The latter involves three topics: (i) group theoretically allowed terms in the spin-rotation Hamiltonian, (ii) matrix elements of these terms between the degenerate components of torsion-rotation E states, calculated using wavefunctions from an earlier global fit of torsion-rotation transitions of methanol in the vt = 0, 1, and 2 states, and (iii) least-squares fits of coefficients of these terms to about 35 experimentally resolved doublet splittings in the quantum number ranges of K = -2 to +2, J = 13 to 34, and vt = 0. Rather pleasing residuals are obtained for these doublet splittings, and a number of narrow transitions, in which no doublet splitting could be detected, are also in agreement with predictions from the theory. Some remaining disagreements between experiment and the present theoretical explanation will be mentioned. G. Yu. Golubiatnikov, S. P. Belov, A. V. Lapinov, "CH_3OH Sub-Doppler Spectroscopy," (Paper MF04) and S.P. Belov, A.V. Burenin, G.Yu. Golubiatnikov, A.V. Lapinov, "What is the Nature of the Doublets in the E-Methanol Lamb-dip Spectra?" (Paper FB07), 68th International Symposium on Molecular Spectroscopy, Columbus, Ohio, June 2013. Li-Hong Xu, J. Fisher, R.M. Lees, H.Y. Shi, J.T. Hougen, J.C. Pearson, B.J. Drouin, G.A. Blake, R. Braakman, "Torsion-Rotation Global Analysis of the First Three Torsional States (vt = 0, 1, 2

  4. Enhanced spin polarization in graphene with spin energy gap induced by spin-orbit coupling and strain

    SciTech Connect

    Liu, Zheng-Fang; Wu, Qing-Ping E-mail: aixichen@ecjtu.jx.cn; Chen, Ai-Xi E-mail: aixichen@ecjtu.jx.cn; Xiao, Xian-Bo; Liu, Nian-Hua

    2014-05-28

    We investigate the possibility of spin polarization in graphene. The result shows that a spin energy gap can be opened in the presence of both spin-orbit coupling and strain. We find that high spin polarization with large spin-polarized current is achieved in the spin energy gap. However, only one of the two modulations is present, no spin polarization can be generated. So the combination of the two modulations provides a way to design tunable spin polarization without need for a magnetic element or an external magnetic field.

  5. Single spin magnetic resonance.

    PubMed

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  6. Single spin magnetic resonance

    NASA Astrophysics Data System (ADS)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  7. Mineral Carbonation in Wet Supercritical CO2: An in situ High-Pressure Magic Angle Spinning Nuclear Magnetic Resonance Study

    NASA Astrophysics Data System (ADS)

    Turcu, R. V.; Hoyt, D. H.; Sears, J. A.; Rosso, K. M.; Felmy, A. R.; Hu, J. Z.

    2011-12-01

    Understanding the mechanisms and kinetics of mineral carbonation reactions relevant to sequestering carbon dioxide as a supercritical fluid (scCO2) in geologic formations is crucial for accurately predicting long-term storage risks. In situ probes that provide molecular-level information at geologically relevant temperatures and pressures are highly desirable and challenging to develop. Magic angle spinning nuclear magnetic resonance (MAS NMR) is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, a supercritical state, or a mixture thereof. However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS sample rotor. In this work, we report development of a unique high pressure MAS NMR capability capable of handling fluid pressure exceeding 170 bars and temperatures up to 80°C, and its application to mineral carbonation in scCO2 under geologically relevant temperatures and pressures. Mineral carbonation reactions of the magnesium silicate mineral forsterite and the magnesium hydroxide brucite reacted with scCO2 (up to 170 bar) and containing variable content of H2O (at, below, and above saturation in scCO2) were investigated at 50 to 70°C. In situ 13C MAS NMR spectra show peaks corresponding to the reactants, intermediates, and the magnesium carbonation products in a single spectrum. For example, Figure 1 shows the reaction dynamics, i.e., the formation and conversion of reaction intermediates, i.e., HCO3- and nesquehonite, to magnesite as a function of time at 70°C. This capability offers a significant advantage over traditional ex situ 13C MAS experiments on similar systems, where, for example, CO2 and HCO3- are not directly observable.

  8. High efficiency of the spin-orbit torques induced domain wall motion in asymmetric interfacial multilayered Tb/Co wires

    NASA Astrophysics Data System (ADS)

    Bang, Do; Awano, Hiroyuki

    2015-05-01

    We investigated current-induced DW motion in asymmetric interfacial multilayered Tb/Co wires for various thicknesses of magnetic and Pt-capping layers. It is found that the driving mechanism for the DW motion changes from interfacial to bulk effects at much thick magnetic layer (up to 19.8 nm). In thin wires, linearly depinning field dependence of critical current density and in-plane field dependence of DW velocity suggest that the extrinsic pinning governs field-induced DW motion and injecting current can be regarded as an effective field. It is expected that the high efficiency of spin-orbit torques in thick magnetic multilayers would have important implication for future spintronic devices based on in-plane current induced-DW motion or switching.

  9. High-spin states in {sup 91,92,93}Rb and {sup 155,156}Pm

    SciTech Connect

    Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Liu, S. H.; Li, K.; Crowell, H. L.; Goodin, C.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.

    2009-09-15

    The excited states of the neutron-rich nuclei {sup 155,156}Pm and {sup 91,92,93}Rb were studied from the spontaneous fission of {sup 252}Cf. The {gamma}-{gamma}-{gamma} and x(Pm)-{gamma}-{gamma} triple coincidence relations were applied to identify the {gamma} transitions. Fourteen, six, three, twelve, and twelve new {gamma} transitions from high-spin states were observed in {sup 155,156}Pm, {sup 91,92}Rb, and {sup 93}Rb (first levels), respectively. The {pi}5/2[532] rotational band in {sup 155}Pm was extended up to 23/2{sup -}. The {pi}g{sub 9/2} particle states and {pi}f{sub 5/2} particle states in {sup 91,93}Rb weakly coupled to {sup 90,92}Kr, respectively, are reported.

  10. Spin-driven ordering of Cr in the equiatomic high entropy alloy NiFeCrCo

    SciTech Connect

    Niu, C.; Zaddach, A. J.; Oni, A. A.; Sang, X.; LeBeau, J. M.; Koch, C. C.; Irving, D. L.; Hurt, J. W.

    2015-04-20

    Spin-driven ordering of Cr in an equiatomic fcc NiFeCrCo high entropy alloy (HEA) was predicted by first-principles calculations. Ordering of Cr is driven by the reduction in energy realized by surrounding anti-ferromagnetic Cr with ferromagnetic Ni, Fe, and Co in an alloyed L1{sub 2} structure. The fully Cr-ordered alloyed L1{sub 2} phase was predicted to have a magnetic moment that is 36% of that for the magnetically frustrated random solid solution. Three samples were synthesized by milling or casting/annealing. The cast/annealed sample was found to have a low temperature magnetic moment that is 44% of the moment in the milled sample, which is consistent with theoretical predictions for ordering. Scanning transmission electron microscopy measurements were performed and the presence of ordered nano-domains in cast/annealed samples throughout the equiatomic NiFeCrCo HEA was identified.

  11. High Spin Torque Efficiency of Magnetic Tunnel Junctions with MgO/CoFeB/MgO Free Layer

    NASA Astrophysics Data System (ADS)

    Jan, Guenole; Wang, Yu-Jen; Moriyama, Takahiro; Lee, Yuan-Jen; Lin, Mark; Zhong, Tom; Tong, Ru-Ying; Torng, Terry; Wang, Po-Kang

    2012-09-01

    We present the results of a perpendicular magnetic tunnel junction (MTJ) that displays simultaneously low critical switching current and voltage, as well as high thermal stability factor. These results were achieved using a free layer of the MgO/CoFeB/MgO structure by increasing the spin torque efficiency to an average of 3.0 kBT/µA for 37-nm-diameter junctions, about three times that of a MgO/CoFeB/Ta free layer, which makes it the highest value reported to date. By comparing two films with different RA, hence different switching voltage and power, we explore the contributions of heating and voltage-modulated anisotropy change to the switching properties.

  12. Magnetic moments, E3 transitions and the structure of high-spin core excited states in 211Rn

    NASA Astrophysics Data System (ADS)

    Poletti, A. R.; Dracoulis, G. D.; Byrne, A. P.; Stuchbery, A. E.; Poletti, S. J.; Gerl, J.; Lewis, P. M.

    1985-05-01

    The results of g-factor measurements of high-spin states in 211Rn are: Ex = 8856 + Δ' keV (Jπ = 63/2-), g = 0.626(7); 6101 + Δ' KeV (49/2+), 0.766(8); 5347 + Δ' KeV (43/2-), 0.74(2); 3927 + Δ KeV (35/2+), 1.017(12); 1578 + Δ KeV (17/2-), 0.912(9). These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in 211Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously.

  13. Spin-on carbon based on fullerene derivatives as hardmask materials for high-aspect-ratio etching

    NASA Astrophysics Data System (ADS)

    Frommhold, Andreas; Palmer, Richard E.; Robinson, Alex P. G.

    2013-07-01

    The advance of lithographic resolution has made it necessary to adopt extremely thin photoresist films for the fabrication of "2× nm" structures in order to mitigate problems such as resist collapse during development but limiting achievable etch depths at the same time. By using multilayer hardmask stacks, a considerable increase in achievable aspect ratio is possible. We have previously presented a fullerene-based spin-on carbon hardmask material capable of high-aspect-ratio etching. We report our latest findings in material characterization of an original and a modified formulation. By using a higher adduct derivative fullerene, the solubility in industry-friendly solvents and thermal stability could be improved. The etching performance and materials characteristics of the new higher-adduct fullerene hardmask were found to be comparable to those of the original hardmask.

  14. Spin-driven ordering of Cr in the equiatomic high entropy alloy NiFeCrCo

    NASA Astrophysics Data System (ADS)

    Niu, C.; Zaddach, A. J.; Oni, A. A.; Sang, X.; Hurt, J. W.; LeBeau, J. M.; Koch, C. C.; Irving, D. L.

    2015-04-01

    Spin-driven ordering of Cr in an equiatomic fcc NiFeCrCo high entropy alloy (HEA) was predicted by first-principles calculations. Ordering of Cr is driven by the reduction in energy realized by surrounding anti-ferromagnetic Cr with ferromagnetic Ni, Fe, and Co in an alloyed L12 structure. The fully Cr-ordered alloyed L12 phase was predicted to have a magnetic moment that is 36% of that for the magnetically frustrated random solid solution. Three samples were synthesized by milling or casting/annealing. The cast/annealed sample was found to have a low temperature magnetic moment that is 44% of the moment in the milled sample, which is consistent with theoretical predictions for ordering. Scanning transmission electron microscopy measurements were performed and the presence of ordered nano-domains in cast/annealed samples throughout the equiatomic NiFeCrCo HEA was identified.

  15. High efficiency of the spin-orbit torques induced domain wall motion in asymmetric interfacial multilayered Tb/Co wires

    SciTech Connect

    Bang, Do; Awano, Hiroyuki

    2015-05-07

    We investigated current-induced DW motion in asymmetric interfacial multilayered Tb/Co wires for various thicknesses of magnetic and Pt-capping layers. It is found that the driving mechanism for the DW motion changes from interfacial to bulk effects at much thick magnetic layer (up to 19.8 nm). In thin wires, linearly depinning field dependence of critical current density and in-plane field dependence of DW velocity suggest that the extrinsic pinning governs field-induced DW motion and injecting current can be regarded as an effective field. It is expected that the high efficiency of spin-orbit torques in thick magnetic multilayers would have important implication for future spintronic devices based on in-plane current induced-DW motion or switching.

  16. High resolution magic angle spinning NMR applied to the analysis of organic compounds bound to solid supports.

    PubMed

    Espinosa, Juan F

    2011-01-01

    In situ structural characterization of organic compounds attached to solid supports can be achieved by high-resolution magic angle spinning NMR (HRMAS NMR), a technique that provides solution-like spectra for resin-bound molecules. This review outlines the principles of the technique, the influence of the solid support on data quality, and NMR experiments that are useful for obtaining valuable information. The review describes, with multiple examples mainly from the last 7 years, how HRMAS NMR has been applied to monitor solid-phase reactions, elucidate reaction products and quantify compound loading on a solid support. Other applications, such as conformational analysis of immobilized compounds and investigation of molecular interactions with compounds in solution, are also discussed.

  17. Efficient and accurate local single reference correlation methods for high-spin open-shell molecules using pair natural orbitals

    NASA Astrophysics Data System (ADS)

    Hansen, Andreas; Liakos, Dimitrios G.; Neese, Frank

    2011-12-01

    A production level implementation of the high-spin open-shell (spin unrestricted) single reference coupled pair, quadratic configuration interaction and coupled cluster methods with up to doubly excited determinants in the framework of the local pair natural orbital (LPNO) concept is reported. This work is an extension of the closed-shell LPNO methods developed earlier [F. Neese, F. Wennmohs, and A. Hansen, J. Chem. Phys. 130, 114108 (2009), 10.1063/1.3086717; F. Neese, A. Hansen, and D. G. Liakos, J. Chem. Phys. 131, 064103 (2009), 10.1063/1.3173827]. The internal space is spanned by localized orbitals, while the external space for each electron pair is represented by a truncated PNO expansion. The laborious integral transformation associated with the large number of PNOs becomes feasible through the extensive use of density fitting (resolution of the identity (RI)) techniques. Technical complications arising for the open-shell case and the use of quasi-restricted orbitals for the construction of the reference determinant are discussed in detail. As in the closed-shell case, only three cutoff parameters control the average number of PNOs per electron pair, the size of the significant pair list, and the number of contributing auxiliary basis functions per PNO. The chosen threshold default values ensure robustness and the results of the parent canonical methods are reproduced to high accuracy. Comprehensive numerical tests on absolute and relative energies as well as timings consistently show that the outstanding performance of the LPNO methods carries over to the open-shell case with minor modifications. Finally, hyperfine couplings calculated with the variational LPNO-CEPA/1 method, for which a well-defined expectation value type density exists, indicate the great potential of the LPNO approach for the efficient calculation of molecular properties.

  18. Lifetimes of high-spin states in {sup 180-184}Pt

    SciTech Connect

    Carpenter, M.P.; Ahmad, I.; Crowell, B.

    1995-08-01

    Over the past few years, lifetimes were measured, using the recoil distance method, to investigate shape-coexistence and shape transitions in the even mass {sup 182-186}Pt isotopes. In all three cases, one observes a sharp increase in the transition quadrupole moment, Q{sub t}, at low frequencies followed by a rapid and significant decline in the backbending region. It was shown that the initial increase in the Q{sub t} can be explained in terms of the mixing at low spins of two bands of very different deformation, and the decline in the backbending region is brought about by mixing between the ground and a two-quasiparticle band. No lifetime information exists for these nuclei above the backbend, and there is some contention whether or not the backbend is due to the alignment of h{sub 9/2} protons, i{sub 13/2} neutrons or the near simultaneous alignment of both. Nilsson-Strutinsky calculations indicate very different shapes for the nuclei after the backbend, depending on which orbitals align. Thus, lifetime information on the states above the backbend should help determine which interpretation is correct. In order to determine the lifetimes of states in the even mass {sup 180-184}Pt nuclei above the backbend, we performed a recent experiment at Gammasphere using a {sup 64}Ni beam on Pb backed Sn targets in order to populate the nucleus of interest via a 4n reaction. At the time of the experiment, thirty-six Ge detectors were available for use in Gammasphere and approximately 100 x 10{sup 6} 3-fold and higher events were taken for each nucleus. Currently, angle-sorted matrices were created from the data, and spectra representing the ground bands show well developed lineshapes for transitions above the backbend. A full lineshape analysis of the data will begin shortly.

  19. Molecular, crystal, and electronic structure of the cobalt(II) complex with 10-(2-benzothiazolylazo)-9-phenanthrol

    NASA Astrophysics Data System (ADS)

    Linko, R. V.; Sokol, V. I.; Polyanskaya, N. A.; Ryabov, M. A.; Strashnov, P. V.; Davydov, V. V.; Sergienko, V. S.

    2013-05-01

    The reaction of 10-(2-benzothiazolylazo)-9-phenanthrol (H L) with cobalt(II) acetate gives the coordination compound [Co L 2] · CHCl3 ( I). The molecular and crystal structure of I is determined by X-ray diffraction. The coordination polyhedron of the Co atom in complex I is an octahedron. The anion L acts as a tridentate chelating ligand and is coordinated to the Co atom through the phenanthrenequinone O1 atom and the benzothiazole N1 atom of the moieties L and the N3 atom of the azo group to form two five-membered metallocycles. The molecular and electronic structures of the compounds H L, L, and Co L 2 are studied at the density functional theory level. The results of the quantum-chemical calculations are in good agreement with the values determined by X-ray diffraction.

  20. Assembling an alkyl rotor to access abrupt and reversible crystalline deformation of a cobalt(II) complex.

    PubMed

    Su, Sheng-Qun; Kamachi, Takashi; Yao, Zi-Shuo; Huang, You-Gui; Shiota, Yoshihito; Yoshizawa, Kazunari; Azuma, Nobuaki; Miyazaki, Yuji; Nakano, Motohiro; Maruta, Goro; Takeda, Sadamu; Kang, Soonchul; Kanegawa, Shinji; Sato, Osamu

    2015-11-04

    Harnessing molecular motion to reversibly control macroscopic properties, such as shape and size, is a fascinating and challenging subject in materials science. Here we design a crystalline cobalt(II) complex with an n-butyl group on its ligands, which exhibits a reversible crystal deformation at a structural phase transition temperature. In the low-temperature phase, the molecular motion of the n-butyl group freezes. On heating, the n-butyl group rotates ca. 100° around the C-C bond resulting in 6-7% expansion of the crystal size along the molecular packing direction. Importantly, crystal deformation is repeatedly observed without breaking the single-crystal state even though the shape change is considerable. Detailed structural analysis allows us to elucidate the underlying mechanism of this deformation. This work may mark a step towards converting the alkyl rotation to the macroscopic deformation in crystalline solids.