Spin Structure Analyses of Antiferromagnets

International Nuclear Information System (INIS)

Chung, Jae Ho; Song, Young Sang; Lee, Hak Bong

2010-05-01

We have synthesized series of powder sample of incommensurate antiferromagnetic multiferroics, (Mn, Co)WO 4 and Al doped Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 , incommensurate antiferromagnetic multiferroics. Their spin structure was studied by using the HRPD. In addition, we have synthesized series of crystalline samples of incommensurate multiferroics, (Mn, Co)WO 4 and olivines. Their spin structure was investigated using neutron diffraction under high magnetic field. As a result, we were able to draw the phase diagram of (Mn, Co)WO 4 as a function of composition and temperature. We learned the how the spin structure changes with increased ionic substitution. Finally we have drawn the phase diagram of the multicritical olivine Mn2SiS4/Mn2GeS4 as a function of filed and temperature through the spin structure studies

Structures of the neutron-rich nuclei observed in fission of {sup 252}Cf

Energy Technology Data Exchange (ETDEWEB)

Ramayya, A. V.; Hamilton, J. H.; Goodin, C. J.; Brewer, N. T.; Hwang, J. K. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Luo, Y. X. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 USA and Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liu, S. H. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 USA and UNRIB/Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States); Rasmussen, J. O.; Lee, I. Y. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Stone, N. J. [Department of Physics, Oxford University, Oxford OX1 3PU (United Kingdom); Daniel, A. V. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna (Russian Federation); Zhu, S. J. [Department of Physics, Tsinghua University, Beijing 100084 (China)

2014-08-14

Analysis of high statistics triple coincidence fission γ data from {sup 252}Cf at Gammasphere including angular correlations yielded well-expanded high-spin level schemes with more complete and reliable spin/parity assignments for {sup 82}Ge, {sup 118,120,122}Cd and {sup 114,115}Rh. Both the quasi-particle/hole couplings and quasi-rotational degrees of freedom are implied to play roles in these Cd isotopes. Evidence for triaxial shapes and octupole components in the Cd isotopes is presented. These Cd isotopes may have triaxial deformations. High-spin level schemes of {sup 114,115}Rh have been established for the first time. The existence of a relatively large signature splitting and an yrare band shows typical features of a triaxially deformed nucleus. Possible excited deformed rotational bands are observed, for the first time, in {sup 82}Ge. From the multipole mixing ratio measurement, the ground state configurations of {sup 109,111}Ru, as well as excited states in {sup 103,107}Mo and {sup 111}Ru were determined.

High-spin structure of 121Xe: triaxiality, band termination and signature inversion

International Nuclear Information System (INIS)

Timar, J.; Paul, E.S.; Beausang, C.W.; Joyce, M.J.; Sharpey-Schafer, J.F.

1995-01-01

High-spin states of the odd-neutron 121 Xe nucleus have been studied with Eurogam using the 96 Zr( 30 Si, 5n) 121 Xe fusion-evaporation reaction. The level scheme has been extended up to a tentative spin of 67/2h at an excitation energy of ∼ 14 MeV. Several new rotational bands have been observed and the previously known bands extended. Two of them lose their regular character at high spins, which may be interpreted as transition from collective behaviour to a regime of noncollective oblate states. The deduced high-spin structure is compared to Woods-Saxon TRS cranking and CSM calculations. Configurations of the bands have been suggested. The νh 1 1/2 band is interpreted as having a triaxial shape. Signature inversion and an unexpectedly large staggering of the B(M1)/B(E2) ratios has been found for one of the bands. Enhanced E1 transitions have been observed between the νd 5/2 and the νh 1 1/2 bands. (orig.)

Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei; Etude spectroscopique de la structure yrast et yrare de noyaux loin de la stabilite

Energy Technology Data Exchange (ETDEWEB)

Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

1999-01-13

The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.

The spin structure of the nucleon

International Nuclear Information System (INIS)

Deur, A.

2008-02-01

This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon

High spin structure of 35Cl and the sd-fp shell gap

International Nuclear Information System (INIS)

Kshetri, Ritesh; Saha Sarkar, M.; Ray, Indrani; Banerjee, P.; Sarkar, S.; Raut, Rajarshi; Goswami, A.; Chatterjee, J.M.; Chattopadhyay, S.; Datta Pramanik, U.; Mukherjee, A.; Dey, C.C.; Bhattacharya, S.; Dasmahapatra, B.; Bhowal, Samit; Gangopadhyay, G.; Datta, P.; Jain, H.C.; Bhowmik, R.K.; Muralithar, S.; Singh, R.P.; Kumar, R.

2007-01-01

The high spin states of 35 Cl have been studied by in-beam γ-spectroscopy following the fusion-evaporation reaction 12 C( 28 Si,αp) 35 Cl at E lab =70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states

Investigation of high spin structure of N ∼ 28 nuclei with PHF model

International Nuclear Information System (INIS)

Naik, Z.

2016-01-01

Nucleus in 50 mass shows verity of high spin phenomena. Some of them are K-Isomer, Band termination, States Beyond Band termination, Superdeformed Structure, Shape co-existence and many more. Some of these phenomena with Projected Hartree-Fock (PHF) model are addressed and the microscopic structure associate with them is discussed

Nuclear structure at high and very high spin theoretical description

International Nuclear Information System (INIS)

Szymanski, Z.

1983-11-01

When the existence of nuclear shell structure is ignored and nuclear motion is assumed to be classical we may expect that the nuclear rotation resembles that of a liquid drop. Energy of the nucleus can be thus considered as a sum of three terms: surface energy, Coulomb energy and rotational energy. Nuclear moment of inertia is assumed to be that of a rigid-body. The results of a calculation of the energy surfaces in rotating nuclei by Cohen, Plasil and Swiatecki are discussed. Cranking procedure is analysed as a tool to investigate nucleonic orbits in a rotating nuclear potential. Some predictions concerning the possible onset of a superdeformed phase are given. The structure of nuclear rotation is examined in the presence of the short-range pairing forces that generate the superfluid correlations in the nucleus. Examples of the Bengtsson-Frauendorf plots (quasiparticle energies versus angular velocity of rotation) are given and discussed. The backbending phenomenon is analysed in terms of band crossing. The dependence of the crossing frequency on the pairing-force strength is discussed. Possibilities of the role of new components in the two-body force (quadrupole-pairing) are considered. Possibilities of the phase transition from superfluid to normal states in the nucleus are analysed. The role of the second (dynamic) moment of inertia I(2) in this analysis is discussed. In spherical weekly deformed nuclei (mostly oblate) angular momentum is aligned parallel to the nuclear symmetry axis. Rotation is of non collective origin in this case. Examples of the analysis of nuclear spectra in this case (exhibiting also the isomeric states called yrast (traps)) are given. Possible forms of the collective excitations superimposed on top of the high-spin states are discussed. In particular, the giant resonance excitations formed on top of the high-spin states are considered and their properties discussed

High-spin states in sd-shell nuclei

International Nuclear Information System (INIS)

Poel, C.J. van der.

1982-01-01

A systematic picture of the structure of high-spin states in the mass range A = 29 - 41 is developed on the basis of experimental results for the nuclei 34 Cl, 38 K and 39 K. It is shown that for 34 Cl the difficulties induced by the relatively low cross section can be overcome. Combination of the data obtained from a γ-γ coincidence experiment with the 24 Mg + 12 C reaction, using the LACSS, and from threshold measurements in the 31 P + α reaction, establishes an unambiguous level scheme. By means of accurate angular-distribution measurements unambiguous spin and parity assignments are made to the high-spin levels. From the results a rather simple shell-model picture for the structure of the high-spin states evolves. Several authors have published experimental work on high-spin states in 39 K, with seriously conflicting conclusions, however, for the spin-parity assignments. The powerful coincidence set-up with the LACSS enables a discrimination between the conflicting results from the previous studies. In this way, unambiguous, model-independent, spin-parity assignments to the high-spin levels are established. Highly selective experimental methods are used to identify the high-spin states of 38 K. It is shown that with a pulsed beam in the reaction 24 Mg + 16 O advantage can be taken of the presence of a long-lived high-spin isomeric level in this nucleus. The gamma-decay of the isomer is extensively studied. With the pulsed beam, also some states above the isomer could be located. The subsequent use of two Compton-suppression spectrometers in a γ-γ coincidence experiment reveals a number of high-spin levels at higher excitation energies. (Auth.)

High spin spectroscopy of 70Ge

International Nuclear Information System (INIS)

Kumar Raju, M.; Sugathan, P.; Seshi Reddy, T.; Thirumala Rao, B.V.; Madhusudhana Rao, P.V.; Muralithar, S.; Singh, R.P.; Bhowmik, R.K.

2011-01-01

Structure of nuclei in mass 70 region is of interest due to presence of a variety of complex phenomenon. In these nuclei rapid change of nuclear shape with proton and neutron numbers, spin and excitation energy. Valance nucleons in f-p-g shell configuration will drive the nuclei towards high deformations. Relatively large values of quadrupole deformation are evident in the even-even nuclei in this region. Present study is aimed to explore the high spin structure of the 70 Ge nucleus. A negative parity structure was reported in an earlier study

Spin Structures in Magnetic Nanoparticles

DEFF Research Database (Denmark)

Mørup, Steen; Brok, Erik; Frandsen, Cathrine

2013-01-01

Spin structures in nanoparticles of ferrimagnetic materials may deviate locally in a nontrivial way from ideal collinear spin structures. For instance, magnetic frustration due to the reduced numbers of magnetic neighbors at the particle surface or around defects in the interior can lead to spin...... canting and hence a reduced magnetization. Moreover, relaxation between almost degenerate canted spin states can lead to anomalous temperature dependences of the magnetization at low temperatures. In ensembles of nanoparticles, interparticle exchange interactions can also result in spin reorientation....... Here, we give a short review of anomalous spin structures in nanoparticles....

The proton spin structure; La structure en spin du proton

Energy Technology Data Exchange (ETDEWEB)

Breton, V.

1996-05-13

The author presents first the theoretical frame of the nucleon spin structure study carried out through the deep inelastic scattering of polarised leptons on a polarised target. The interest of the lepton scattering reaction to study the hadronic structure is discussed and the formalism of the inclusive inelastic scattering presented. If the target and the beam are both polarised, the formalism enables to connect the experimentally measured asymmetries to the contribution of quarks to the spin of nucleon. The recent knowledge about the nucleon spin structure is also presented. The Bjorken sum rule is then discussed: it correlates the difference of spin structure between proton and neutron to the neutron lifetime. Then, the author mentions the experimental results of SMC (CERN) and E142, E143 (SLAC). The transition from rough asymmetry to the g sub 1 structure function integral is discussed as well as the main causes of uncertainty. Compared to theoretical data, the measurements confirm the reliability of the Bjorken sum rule. They also confirm the deficit of the quark contribution with respect to the naive unpolarized strange sea model. The possible origins of this discrepancy and the contributions of the current and planned experiments are also discussed. Finally, the author brings up the next major step for nucleon spin studies: the estimation of the gluon contribution. He discusses the experimental knowledge about the polarised gluon distribution function with regard to the multiple existing parameter set. Concerning the experimental determination of this distribution function, outlooks are proposed with respect to feasibility on current experimental facilities. (N.T.). 134 refs.

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

Science.gov (United States)

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.

Nucleon Spin Structure: Longitudinal and Transverse

International Nuclear Information System (INIS)

Chen, Jian-Ping

2011-01-01

Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.

Nuclear structure at high-spin and large-deformation

International Nuclear Information System (INIS)

Shimizu, Yoshifumi R.

2000-01-01

Atomic nucleus is a finite quantal system and shows various marvelous features. One of the purposes of the nuclear structure study is to understand such features from a microscopic viewpoint of nuclear many-body problem. Recently, it is becoming possible to explore nuclear states under 'extreme conditions', which are far different from the usual ground states of stable nuclei, and new aspects of such unstable nuclei attract our interests. In this lecture, I would like to discuss the nuclear structure in the limit of rapid rotation, or the extreme states with very large angular momenta, which became accessible by recent advent of large arrays of gamma-ray detecting system; these devices are extremely useful to measure coincident multiple γ-rays following heavy-ion fusion reactions. Including such experimental aspects as how to detect the nuclear rotational states, I review physics of high-spin states starting from the elementary subjects of nuclear structure study. In would like also to discuss the extreme states with very large nuclear deformation, which are easily realized in rapidly rotating nuclei. (author)

High energy hadron spin-flip amplitude

International Nuclear Information System (INIS)

Selyugin, O.V.

2016-01-01

The high-energy part of the hadron spin-flip amplitude is examined in the framework of the new high-energy general structure (HEGS) model of the elastic hadron scattering at high energies. The different forms of the hadron spin-flip amplitude are compared in the impact parameter representation. It is shown that the existing experimental data of the proton-proton and proton-antiproton elastic scattering at high energy in the region of the diffraction minimum and at large momentum transfer give support in the presence of the energy-independent part of the hadron spin-flip amplitude with the momentum dependence proposed in the works by Galynskii-Kuraev. [ru

High spin structure of {sup 35}Cl and the sd-fp shell gap

Energy Technology Data Exchange (ETDEWEB)

Kshetri, Ritesh [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Saha Sarkar, M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India)]. E-mail: maitrayee.sahasarkar@saha.ac.in; Ray, Indrani [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Banerjee, P. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Sarkar, S. [Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Raut, Rajarshi [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Goswami, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, J.M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Datta Pramanik, U. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Mukherjee, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dey, C.C. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhattacharya, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dasmahapatra, B. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhowal, Samit [Department of Physics, Surendranath Evening College, Kolkata 700009 (India); Gangopadhyay, G. [University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Datta, P. [Anandamohan College, 102/1, Raja Rammohan Sarani, Kolkata 700009 (India); Jain, H.C. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bhowmik, R.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Muralithar, S.; Singh, R.P.; Kumar, R. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

2007-01-15

The high spin states of {sup 35}Cl have been studied by in-beam {gamma}-spectroscopy following the fusion-evaporation reaction {sup 12}C({sup 28}Si,{alpha}p){sup 35}Cl at E{sub lab}=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states.

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

Energy Technology Data Exchange (ETDEWEB)

Yan, Qiang; Zhou, Liping, E-mail: zhoulp@suda.edu.cn; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China)

2016-04-21

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

Discrete spectroscopy in {sup 180}Os at high spins

Energy Technology Data Exchange (ETDEWEB)

Marti, G; Venkova, Ts; Morek, T; Schnare, H; Gast, W; Georgiev, A; Spohr, K M; Lieder, R M [Institut fuer Kernphysik, KFA-Juelich (Germany); Maier, K H [Hahn-Meitner-Institut Berlin GmbH (Germany); Zell, K O [Institut fuer Kernphysik, Universitaet Koeln (Germany)

1992-08-01

New information on rotational bands in {sup 180}Os was obtained from a discrete spectroscopy experiment in which the final nucleus was populated through the {sup 150}Nd({sup 36}S,6n) reaction at 177 MeV. A new strongly-coupled rotational band starting at a relatively high excitation energy was found. The observation and placement of the 185.6 keV in the level scheme gives strong support to a hypothetical 2-quasineutron configuration assigned to the 7{sup -} isomeric bands in {sup 180}Os and the isotone {sup 178}W. Band mixing between the (-,1){sub 1} and (-,1){sub 3} bands of same parity and signature was observed, and the interaction strength was estimated from experimental branching ratios. The authors` results confirm a previous assignment for the yrast and yrare sequences in this nucleus. With the identification of new transitions above the states with I {approx_equal} 24, previously assigned bands had to be revised, with the result that the second band crossing vanishes. 23 refs., 3 figs.

High spin levels in 151Ho

International Nuclear Information System (INIS)

Gizon, J.; Gizon, A.; Andre, S.; Genevey, J.; Jastrzebski, J.; Kossakowski, R.; Moszinski, M.; Preibisz, Z.

1981-02-01

We report here on the first study of the level structure of 151 Ho. High spin levels in 151 Ho have been populated in the 141 Pr + 16 O and 144 Sm + 12 C reactions. The level structure has been established up to 6.6 MeV energy and the spins and particles determined up to 49/2 - . Most of the proposed level configurations can be explained by the coupling of hsub(11/2) protons to fsub(7/2) and/or hsub(9/2) neutrons. An isomer with 14 +- 3 ns half-life and a delayed gamma multiplicity equal to 17 +- 2 has been found. Its spin is larger than 57/2 h units

Intrinsic properties of high-spin band structures in triaxial nuclei

Science.gov (United States)

Jehangir, S.; Bhat, G. H.; Sheikh, J. A.; Palit, R.; Ganai, P. A.

2017-12-01

The band structures of 68,70Ge, 128,130,132,134Ce and 132,134,136,138Nd are investigated using the triaxial projected shell model (TPSM) approach. These nuclei depict forking of the ground-state band into several s-bands and in some cases, both the lowest two observed s-bands depict neutron or proton character. It was discussed in our earlier work that this anomalous behaviour can be explained by considering γ-bands based on two-quasiparticle configurations. As the parent band and the γ-band built on it have the same intrinsic structure, g-factors of the two bands are expected to be similar. In the present work, we have undertaken a detailed investigation of g-factors for the excited band structures of the studied nuclei and the available data for a few high-spin states are shown to be in fair agreement with the predicted values.

Internal spin structure of the nucleon

International Nuclear Information System (INIS)

Hughes, V.W.; Kuti, J.

1983-01-01

The study of the structure of the proton and neutron through deep inelastic scattering, initially with electrons but subsequently with muons and neutrinos as well, has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD). One important aspect of these theoretical and experimental developments is the two spin-dependent structure functions, which are independent of the two spin-averaged structure functions and define the internal spin structure of the nucleon. Since both quarks and gluons possess spin and the forces between them are spin dependent, we can expect important information on these forces and on nucleon structure to be obtained through the study of the spindependent aspects of the nucleon wave function, as has been the case before in atomic and nuclear physics

Nuclear high-spin data for A = 174, 176 and 184

Energy Technology Data Exchange (ETDEWEB)

Junde, Huo [Jilin Univ. (China). Dept. of Physics

1996-06-01

Nuclear high-spin data are important in the frontier areas of nuclear structure physics. The information on A = 174, 176 and 184 mass chains from various reaction experiments together with their adopted high-spin levels and gamma transition properties are presented and discussed. High-spin data for A = 174, 176 and 184 mass chains were evaluated in 1995.

16th Workshop on High Energy Spin Physics

CERN Document Server

2016-01-01

The Workshop will cover a wide range of spin phenomena at high and intermediate energies such as: recent experimental data on spin physics the nucleon spin structure and GPD's spin physics and QCD spin physics in the Standard Model and beyond T-odd spin effects polarization and heavy ion physics spin in gravity and astrophysics the future spin physics facilities spin physics at NICA polarimeters for high energy polarized beams acceleration and storage of polarized beams the new polarization technology related subjects The Workshop will be held in the Bogoliubov Laboratory of Theoretical Physics of the Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia. The program of the workshop will include plenary and parallel (if necessary) sessions. Plenary sessions will be held in the Conference Hall. Parallel sections will take place in the same building. There will be invited talks (up to 40 min) and original reports (20 min). The invited speakers will present new experimental and theoretical re...

Vibration dependence of the tensor spin-spin and scalar spin-spin hyperfine interactions by precision measurement of hyperfine structures of 127I2 near 532 nm

International Nuclear Information System (INIS)

Hong Fenglei; Zhang Yun; Ishikawa, Jun; Onae, Atsushi; Matsumoto, Hirokazu

2002-01-01

Hyperfine structures of the R(87)33-0, R(145)37-0, and P(132)36-0 transitions of molecular iodine near 532 nm are measured by observing the heterodyne beat-note signal of two I 2 -stabilized lasers, whose frequencies are bridged by an optical frequency comb generator. The measured hyperfine splittings are fit to a four-term Hamiltonian, which includes the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions, with an accuracy of ∼720 Hz. High-accurate hyperfine constants are obtained from this fit. Vibration dependences of the tensor spin-spin and scalar spin-spin hyperfine constants are determined for molecular iodine, for the first time to our knowledge. The observed hyperfine transitions are good optical frequency references in the 532-nm region

High-spin structure of neutron-rich Dy isotopes

Indian Academy of Sciences (India)

Neutron-rich Dy isotopes; high-spin states; g-factors; cranked HFB theory. ... for 164Dy marking a clear separation in the behaviour as a function of neutron ... cipal x-axis as the cranking axis) in this mass region we have planned to make a sys-.

High-spin nuclear spectroscopy

International Nuclear Information System (INIS)

Diamond, R.M.

1986-07-01

High-spin spectroscopy is the study of the changes in nuclear structure, properties, and behavior with increasing angular momentum. It involves the complex interplay between collective and single-particle motion, between shape and deformation changes, particle alignments, and changes in the pairing correlations. A review of progress in theory, experimentation, and instrumentation in this field is given

Study of high-spin structure of the nuclei around A∼120 near proton-drip line

International Nuclear Information System (INIS)

Ray, I; Datta Pramanik, U.; Banerjee, P.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Mukherjee, A.; Mukherjee, B.; Saha Sarkar, M.; Basu, S.K.; Bhowmik, R.K.; Rakesh Kumar; Muralithar, S.; Singh, R.P.; Mandal, S.; Ranjet

2005-01-01

It would be interesting to explore the shell structure for nuclei near proton-drip line. The nuclei around A∼ 110-130 region show a wide range of interesting features in high spin states which reflect different types of symmetry breaking mechanisms as well as maintaining symmetries

Gross shell structure at high spin in heavy nuclei

International Nuclear Information System (INIS)

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

2003-01-01

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

Spin crossover and high spin filtering behavior in Co-Pyridine and Co-Pyrimidine molecules

Science.gov (United States)

Wen, Zhongqian; Zhou, Liping; Cheng, Jue-Fei; Li, Shu-Jin; You, Wen-Long; Wang, Xuefeng

2018-03-01

We present a theoretical study on a series of cobalt complexes, which are constructed with cobalt atoms and pyridine/pyrimidine rings, using density functional theory. We investigate the structural and electric transport properties of spin crossover (SCO) Co complex with two spin states, namely low-spin configuration [LS] and high-spin configuration [HS]. Energy analyses of the two spin states imply that the SCO Co-Pyridine2 and Co-Pyrimidine2 complexes may display a spin transition process accompanied by a geometric modification driven by external stimuli. A nearly perfect spin filtering effect is observed in the Co-Pyrimidine2 complex with [HS] state. In addition, we also discover the contact-dependent transmission properties of Co-Pyridine2. These findings indicate that SCO Co complexes are promising materials for molecular spintronic devices.

Electronic structure of spin systems

Energy Technology Data Exchange (ETDEWEB)

Saha-Dasgupta, Tanusri

2016-04-15

Highlights: • We review the theoretical modeling of quantum spin systems. • We apply the Nth order muffin-tin orbital electronic structure method. • The method shows the importance of chemistry in the modeling. • CuTe{sub 2}O{sub 5} showed a 2-dimensional coupled spin dimer behavior. • Ti substituted Zn{sub 2}VO(PO{sub 4}){sub 2} showed spin gap behavior. - Abstract: Low-dimensional quantum spin systems, characterized by their unconventional magnetic properties, have attracted much attention. Synthesis of materials appropriate to various classes within these systems has made this field very attractive and a site of many activities. The experimental results like susceptibility data are fitted with the theoretical model to derive the underlying spin Hamiltonian. However, often such a fitting procedure which requires correct guess of the assumed spin Hamiltonian leads to ambiguity in deciding the representative model. In this review article, we will describe how electronic structure calculation within the framework of Nth order muffin-tin orbital (NMTO) based Wannier function technique can be utilized to identify the underlying spin model for a large number of such compounds. We will show examples from compounds belonging to vanadates and cuprates.

High-frequency EPR on high-spin transition-metal sites

NARCIS (Netherlands)

Mathies, Guinevere

2012-01-01

The electronic structure of transition-metal sites can be probed by electron-paramagnetic-resonance (EPR) spectroscopy. The study of high-spin transition-metal sites benefits from EPR spectroscopy at frequencies higher than the standard 9.5 GHz. However, high-frequency EPR is a developing field. In

New Results on Testing Duality in Spin Structure from Jefferson Lab

Energy Technology Data Exchange (ETDEWEB)

Nilanga Liyanage

2005-10-01

The Bloom-Gilman duality has been experimentally demonstrated for spin independent structure functions. Duality is observed when the smooth scaling curve at high momentum transfer is an average over the resonance bumps at lower momentum transfer, but at the same value of scaling variable x. Signs of quark-hadron duality for the spin Dependant structure function g1 of the proton has been recently reported by the Hermes collaboration. Experimental Halls A, B and C at Jefferson lab have recently measured spin structure functions in the resonance region for the proton and the neutron. Data from these experiments combined with Deep-Inelastic-Scattering data provide a precision test of quark-hadron duality predictions for spin structure functions for both the proton and the neutron. This will be one of the first precision tests of spin and flavor dependence of quark-hadron duality.

High spin studies with radioactive ion beams

International Nuclear Information System (INIS)

Garrett, J.D.

1992-01-01

The variety of new research possibilities afforded by the culmination of the two frontier areas of nuclear structure: high spin and studies far from nuclear stability (utilizing intense radioactive ion beams) are discussed. Topics presented include: new regions of exotic nuclear shape (e.g. superdeformation, hyperdeformation, and reflection-asymmetric shapes); the population of and consequences of populating exotic nuclear configurations; and complete spectroscopy (i.e. the overlap of state of the art low-and high-spin studies in the same nucleus)

Spin Filters as High-Performance Spin Polarimeters

International Nuclear Information System (INIS)

Rougemaille, N.; Lampel, G.; Peretti, J.; Drouhin, H.-J.; Lassailly, Y.; Filipe, A.; Wirth, T.; Schuhl, A.

2003-01-01

A spin-dependent transport experiment in which hot electrons pass through a ferromagnetic metal / semiconductor Schottky diode has been performed. A spin-polarized free-electron beam, emitted in vacuum from a GaAs photocathode, is injected into the thin metal layer with an energy between 5 and 1000 eV above to the Fermi level. The transmitted current collected in the semiconductor substrate increases with injection energy because of secondary - electron multiplication. The spin-dependent part of the transmitted current is first constant up to about 100 eV and then increases by 4 orders of magnitude. As an immediate application, the solid-state hybrid structure studied here leads to a very efficient and compact device for spin polarization detection

Backbending in high spin states of 80Kr

International Nuclear Information System (INIS)

Kaushik, M.; Saxena, G.

2014-01-01

The study of high-spin states in Kr isotopes near A = 80 region has attracted a considerable interest in recent years. A variety of shapes, shape coexistence as well as backbending phenomenon have been studied in the many of Kr isotopes. In the case of 80 Kr, the high spin structure has been studied by Doring et al. rather extensively and has provided considerable insight into the structure of f-p-g shell nuclei and the competition between single-particle and collective degrees of freedom. Backbending phenomenon is reported in 80 Kr at ω = 0.5 MeV

Spin dependent photon structure functions

International Nuclear Information System (INIS)

Manohar, A.V.; Massachusetts Inst. of Tech., Cambridge

1989-01-01

Spin dependent structure functions of the photon are studied using the operator product expansion. There are new twist-two photon and gluon operators which contribute. The structure functions g 1 and F 3 are calculable in QCD, but differ from their free quark values. The corrections to F 3 are suppressed by 1/log Q 2 . The calculation is an extension of the analysis of Witten for the spin averaged structure functions F 1 and F 2 . (orig.)

High spin studies with radioactive ion beams

Energy Technology Data Exchange (ETDEWEB)

Garrett, J D [Oak Ridge National Lab., TN (United States)

1992-08-01

The variety of new research possibilities afforded by the culmination of the two frontier areas of nuclear structure: high spin and studies far from nuclear stability (utilizing intense radioactive ion beams) are discussed. Topics presented include: new regions of exotic nuclear shape (e.g. superdeformation, hyperdeformation, and reflection-asymmetric shapes); the population of and consequences of populating exotic nuclear configurations; and, complete spectroscopy (i.e. the overlap of state of the art low- and high-spin studies in the same nucleus). (author). 47 refs., 8 figs.

Highly spin-polarized materials and devices for spintronics∗.

Science.gov (United States)

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, Co 2 Cr 1 - x Fe x Al (CCFA( x )) and Co 2 FeSi 1 - 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 Co 2 FeSi 0.5 Al 0.5 (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 L2 1 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 CoFe 2 film deposited on a MgO (001) single crystal substrate, wherein the spinel

Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field

Energy Technology Data Exchange (ETDEWEB)

Rezania, H., E-mail: rezania.hamed@gmail.com

2017-02-01

We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.

Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field

International Nuclear Information System (INIS)

Rezania, H.

2017-01-01

We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.

The spin structure of the deuteron

Energy Technology Data Exchange (ETDEWEB)

Frois, B. [DAPNIA/SPHN, Gif-sur-Yvette (France)

1994-12-01

The Spin Muon Collaboration (SMC) has measured for the first time the spin-dependent structure function g{sub 1}{sup d} of the deuteron in the deep inelastic scattering of polarized muons on polarized deuterons in the kinematic range Q{sup 2} > 1 GeV{sup 2}, 0.006 < x < 0.6. The first moment {Gamma}{sub 1}{sup d} = {integral}{sub 0}{sup 1}g{sub 1}{sup d}dx = 0.023 {+-} 0.020(stat.) {+-} 0.015(syst.) is smaller than the prediction of the Ellis-Jaffe sum rules. The author finds that the fraction of the nucleon spin carried by strange quarks {Delta}s is appreciable and negative. Using earlier measurements of g{sub 1}{sup p}, the group can infer the first moment of the spin-dependent neutron structure function g{sub 1}{sup n}. The combined analysis of all the available data on the spin-dependent structure functions of the nucleon shows an excellent agreement among the data sets. The author does not find significant deviations from the prediction of the Bjorken sum rule.

Surface induces different crystal structures in a room temperature switchable spin crossover compound.

Science.gov (United States)

Gentili, Denis; Liscio, Fabiola; Demitri, Nicola; Schäfer, Bernhard; Borgatti, Francesco; Torelli, Piero; Gobaut, Benoit; Panaccione, Giancarlo; Rossi, Giorgio; Degli Esposti, Alessandra; Gazzano, Massimo; Milita, Silvia; Bergenti, Ilaria; Ruani, Giampiero; Šalitroš, Ivan; Ruben, Mario; Cavallini, Massimiliano

2016-01-07

We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations.

Structural and magnetic characterization of Fe2CrSi Heusler alloy nanoparticles as spin injectors and spin based sensors

Science.gov (United States)

Saravanan, G.; Asvini, V.; Kalaiezhily, R. K.; Parveen, I. Mubeena; Ravichandran, K.

2018-05-01

Half-metallic ferromagnetic [HMF] nanoparticles are of considerable interest in spintronics applications due to their potential use as a highly spin polarized current source. HMF exhibits a semiconductor in one spin band at the Fermi level Ef and at the other spin band they poses strong metallic nature which shows 100 % spin polarization at Ef. Fe based full Heusler alloys are primary interest due to high Curie temperature. Fe2CrSi Heusler alloys are synthesized using metallic powders of Fe, Cr and Si by mechanical alloying method. X-Ray diffractions studies were performed to analyze the structural details of Fe2CrSi nanoparticles with High resolution scanning electron microscope (HRSEM) studies for the morphological details of nanoparticles and magnetic properties were studied using Vibrating sample magnetometer (VSM). XRD Data analysis conforms the Heusler alloy phase showing the existence of L21 structure. Magnetic properties are measured for synthesized samples exhibiting a soft magnetic property possessing low coercivity (HC = 60.5 Oe) and saturation magnetic moment of Fe2CrSi is 3.16 µB, which is significantly higher than the ideal value of 2 µB from the Slater-Pauling rule due to room temperature measurement. The change in magnetic properties are half-metallic nature of Fe2CrSi is due to the shift of the Fermi level with respect to the gap were can be used as spin sensors and spin injectors in magnetic random access memories and other spin dependent devices.

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

International Nuclear Information System (INIS)

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

STUDY OF THE HIGH-SPIN STRUCTURE OF PM-146

NARCIS (Netherlands)

RZACAURBAN, T; DURELL, JL; PHILLIPS, WR; VARLEY, BJ; HESS, CP; PEARSON, CJ; VERMEER, WJ; VIEU, C; DIONISIO, JS; PAUTRAT, M; Urban, W

1995-01-01

Excited states in Pm-146 have been investigated through the Xe-136(N-15,5n) and the Nd-146(d,xn) compound-nucleus reactions. A level scheme extending up to 6.9 MeV of excitation energy and (I = 25HBAR) is proposed. Most of the high-spin levels are interpreted in terms of multi-particle-hole states

High spin states of 141Pm

Science.gov (United States)

Bhattacharyya, Sarmishtha; Chanda, Somen; Bhattacharjee, Tumpa; Basu, Swapan Kumar; Bhowmik, R. K.; Muralithar, S.; Singh, R. P.; Ghugre, S. S.

2004-01-01

The high spin states in the N=80 odd- A141Pm nucleus have been investigated by in-beam γ-spectroscopic techniques following the reaction 133Cs( 12C, 4n) 141Pm at E=65 MeV using a modest γ detector array, consisting of seven Compton-suppressed high purity germanium detectors and a multiplicity ball of 14 bismuth germanate elements. Thirty new γ rays have been assigned to 141Pm on the basis of γ-ray singles and γγ-coincidence data. The level scheme of 141Pm has been extended upto an excitation energy of 5.2 MeV and spin {35}/{2}ℏ and 16 new levels have been proposed. Spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced directional correlation orientation ratios for strong transitions. The meanlives of a few excited states have been determined from the pulsed beam- γγ coincidence data using the generalised centroid-shift method. The level structure is discussed in the light of known systematics of neighbouring N=80 isotonic nuclei.

Development of high-spin isomer beams

International Nuclear Information System (INIS)

Zhou Xiaohong

2000-01-01

The physical motivations with high-spin isomer beams were introduced. Taking HSIB of RIKEN as an example, the methods to produce, separate, transport and purity high-spin isomer beams were described briefly, and the detection of γ rays emitted from the reactions induced by the high-spin isomer beams was presented. Finally, the progress to develop the high-spin isomers in the N = 83 isotones as second beams was stressed

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

Energy Technology Data Exchange (ETDEWEB)

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

High spin isomer beam line at RIKEN

Energy Technology Data Exchange (ETDEWEB)

Kishida, T.; Ideguchi, E.; Wu, H.Y. [Institute of Physical and Chemical Research, Saitama (Japan)] [and others

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.

Fine structure and optical pumping of spins in individual semiconductor quantum dots

Science.gov (United States)

Bracker, Allan S.; Gammon, Daniel; Korenev, Vladimir L.

2008-11-01

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information.

Fine structure and optical pumping of spins in individual semiconductor quantum dots

International Nuclear Information System (INIS)

Bracker, Allan S; Gammon, Daniel; Korenev, Vladimir L

2008-01-01

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information

Proton spin structure in the rest frame

International Nuclear Information System (INIS)

Zavada, P.

1997-01-01

It is shown that the quark-parton model in the standard infinite momentum approach overestimates the proton spin structure function g 1 (x) in comparison with the approach taking consistently into account the internal motion of quarks described by a spherical phase space in the proton rest frame. Particularly, it is shown the first moment of the spin structure function in the latter approach, assuming only the valence quarks contribution to the proton spin, does not contradict the experimental data. copyright 1997 The American Physical Society

Spin structures in antiferromagnetic nanoparticles

DEFF Research Database (Denmark)

Brok, Erik

dependence of the magnetisation in certain nanoparticle systems, as welll bulk systems with spin canting due to defects. In accordance with this model magnetisation measurements on goethtie (a-FeOOH) nanoparticles are presented, showing a low temperature increase in the magnetisation. The spin orientation...... experimental data from unpolarised neutron diffraction. The spin orientation is found to be close to the particle plane, which is the (111) plane of the FCC structure of NiO for particles with thickness ranging from 2.2 nm to bulk (= 200 nm) particles. In the smallest particles, with a thickness of 2.0 nm, we...

Spin structure of the proton

International Nuclear Information System (INIS)

Nathan Isgur

1995-01-01

In these lectures the author argues that their response to the spin crisis should not be to abandon the naive quark model baby, but rather to allow it to mature. He begin by recalling what a beautiful baby the quark model is via an overview of its successes in spectroscopy, dynamics, and valence spin structure. He also introduces the conservative hypothesis that dynamical qanti q pairs are its key missing ingredient. He then discusses dressing the baby. He first shows that it can be clothed in glue without changing its spectroscopic successes. In the process, several dynamical mysteries associated with quark model spectroscopy are potentially explained. Next, he dresses the baby in qanti q pairs, first showing that this can be done without compromising the naive quark model's success with either spectroscopy or the OZI rule. Finally, he shows that despite their near invisibility elsewhere, pairs do play an important role in the proton's spin structure by creating an antipolarized qanti q sea. In the context of an explicit calculation he demonstrate that it is plausible that the entire ''spin crisis'' arises from this effect

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

Energy Technology Data Exchange (ETDEWEB)

Burkardt, M. [New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics; Miller, C.A. [TRIUMF, Vancouver, BC (Canada); Nowak, W.D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2009-08-15

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 is reviewed and an outlook for the future is offered. (orig.)

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

International Nuclear Information System (INIS)

Burkardt, M.; Nowak, W.D.

2009-08-01

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 is reviewed and an outlook for the future is offered. (orig.)

A new high-pressure phase of Fe2SiO4 and the relationship between spin and structural transitions

Science.gov (United States)

Yamanaka, T.; Kyono, A.; Nakamoto, Y.; Kharlamova, S. A.; Struzhkin, V. V.; Gramsch, S.; Mao, H.; Hemley, R. J.

2013-12-01

Structure transformation of Fe2SiO4 Angle-dispersive powder x-ray diffraction was carried out at beam line 16-BMD APS. Structure of a new high-pressure phase of I-Fe2SiO4 spinel was determined by Rietveld profile fitting of x-ray diffraction data up to 64GPa at ambient temperature. A structural transition from the cubic spinel to the new structure was observed at 34GPa. Diffraction patterns taken at 44.6GPa and 54.6GPa indicate a two-phase mixture of spinel and new high-pressure phase. Reversible transition from I-Fe2SiO4 to spinel was confirmed. Laser heating experiment at 1500K proved the decomposition of Fe2SiO4 spinel to two oxides of FeO and SiO2. Spin transition X-ray emission measurements of Fe2SiO4 were carried out up to 65GPa at ambient temperature at beam line 16-IDD APS. The spin transition exerts an influence to Fe2SiO4 spinel structure and triggers two distinct curves of the lattice constant in the spinel phase. Although the compression curve of the spinel is discontinuous at approximately 20 GPa, Fe Kβ emission measurements show that the transition from a high spin (HS) to an intermediate spin (IS) state begins at 17GPa in the spinel phase. The IS electronic state is gradually enhanced with pressure, which results in an isostructural phase transition. HS-to-LS transition of iron bearing spinels starts from 15.6GPa in Fe3O4 and 19.6GPa in Fe2TiO4. The transition is more capable due to Fe2+ in the octahedral site. The extremely shortened octahedral bonds result in a distortion of 6-fold cation site. New structure of Fe2SiO4 Monte Carlo method was applied to find candidates for the high-pressure phase using the diffraction intensities with fixed lattice constants determined by DICVOL. Rietveld profile fitting was then performed using the initial model. The new structure is a body centered orthorhombic phase (I-Fe2SiO4) with space group Imma and Z=4, with two crystallographically distinct FeO6 octahedra. Silicon exists in six-fold coordination in I-Fe2Si

The impact of structural relaxation on spin polarization and magnetization reversal of individual nano structures studied by spin-polarized scanning tunneling microscopy.

Science.gov (United States)

Sander, Dirk; Phark, Soo-Hyon; Corbetta, Marco; Fischer, Jeison A; Oka, Hirofumi; Kirschner, Jürgen

2014-10-01

The application of low temperature spin-polarized scanning tunneling microscopy and spectroscopy in magnetic fields for the quantitative characterization of spin polarization, magnetization reversal and magnetic anisotropy of individual nano structures is reviewed. We find that structural relaxation, spin polarization and magnetic anisotropy vary on the nm scale near the border of a bilayer Co island on Cu(1 1 1). This relaxation is lifted by perimetric decoration with Fe. We discuss the role of spatial variations of the spin-dependent electronic properties within and at the edge of a single nano structure for its magnetic properties.

Unique spin-polarized transmission effects in a QD ring structure

Science.gov (United States)

Hedin, Eric; Joe, Yong

2010-10-01

Spintronics is an emerging field in which the spin of the electron is used for switching purposes and to communicate information. In order to obtain spin-polarized electron transmission, the Zeeman effect is employed to produce spin-split energy states in quantum dots which are embedded in the arms of a mesoscopic Aharonov-Bohm (AB) ring heterostructure. The Zeeman splitting of the QD energy levels can be induced by a parallel magnetic field, or by a perpendicular field which also produces AB-effects. The combination of these effects on the transmission resonances of the structure is studied analytically and several parameter regimes are identified which produce a high degree of spin-polarized output. Contour and line plots of the weighted spin polarization as a function of electron energy and magnetic field are presented to visualize the degree of spin-polarization. Taking advantage of these unique parameter regimes shows the potential promise of such devices for producing spin-polarized currents.

Structure of Se at high spin

Indian Academy of Sciences (India)

the proton-rich mass-80 nuclei shows considerable variation in going from one nucleus to ... shell gaps at N, Z = 34, 36 and 38 at large deformation. ... systematic increase of the B(E2) values for spins up to I = 14-h has been observed [2] in. 72.

Spin Transport in Nondegenerate Si with a Spin MOSFET Structure at Room Temperature

Science.gov (United States)

Sasaki, Tomoyuki; Ando, Yuichiro; Kameno, Makoto; Tahara, Takayuki; Koike, Hayato; Oikawa, Tohru; Suzuki, Toshio; Shiraishi, Masashi

2014-09-01

Spin transport in nondegenerate semiconductors is expected to pave the way to the creation of spin transistors, spin logic devices, and reconfigurable logic circuits, because room-temperature (RT) spin transport in Si has already been achieved. However, RT spin transport has been limited to degenerate Si, which makes it difficult to produce spin-based signals because a gate electric field cannot be used to manipulate such signals. Here, we report the experimental demonstration of spin transport in nondegenerate Si with a spin metal-oxide-semiconductor field-effect transistor (MOSFET) structure. We successfully observe the modulation of the Hanle-type spin-precession signals, which is a characteristic spin dynamics in nondegenerate semiconductors. We obtain long spin transport of more than 20 μm and spin rotation greater than 4π at RT. We also observe gate-induced modulation of spin-transport signals at RT. The modulation of the spin diffusion length as a function of a gate voltage is successfully observed, which we attribute to the Elliott-Yafet spin relaxation mechanism. These achievements are expected to lead to the creation of practical Si-based spin MOSFETs.

Spin structure function measurements with polarized protons and electrons at HERA

International Nuclear Information System (INIS)

Ball, R.D.; Deshpande, A.; Forte, S.; Hughes, V.W.; Lichtenstadt, J.; Ridolfi, G.

1995-01-01

Useful insights into the spin structure functions of the nucleon can be achieved by measurements of spin-dependent asymmetries in inclusive scattering of high energy polarized electrons by high energy polarized protons at HERA. Such an experiment would be a natural extension of the polarized lepton-nucleon scattering experiments presently carried out at CERN and SLAC. We present here estimates of possible data in the extended kinematic range of HERA and associated statistical errors. (orig.)

Spin-polarons and high-Tc superconductivity

International Nuclear Information System (INIS)

Wood, R.F.

1994-03-01

The spin-polaron concept is introduced in analogy to ionic and electronic polarons and the assumptions underlying the author's approach to spin-polaron mediated high-T c superconductivity are discussed. Elementary considerations about the spin-polaron formation energy are reviewed and the possible origin of the pairing mechanism illustrated schematically. The electronic structure of the CuO 2 planes is treated from the standpoint of antiferromagnetic band calculations that lead directly to the picture of holes predominantly on the oxygen sublattice in a Mott-Hubbard/charge transfer insulator. Assuming the holes to be described in a Bloch representation but with the effective mass renormalized by spin-polaron formation, equations for the superconducting gap, Δ, and transition temperature, T c , are developed and the symmetry of Δ discussed. After further simplifications, T c is calculated as a function of the carrier concentration, x. It is shown that the calculated behavior of T c (x) follows the experimental results closely and leads to a natural explanation of the effects of under- and over-doping. The paper concludes with a few remarks about the evidence for the carriers being fermions (polarons) or bosons (bipolarons)

Spin and lattice structures of single-crystalline SrFe2As2

Science.gov (United States)

Zhao, Jun; Ratcliff, W., II; Lynn, J. W.; Chen, G. F.; Luo, J. L.; Wang, N. L.; Hu, Jiangping; Dai, Pengcheng

2008-10-01

We use neutron scattering to study the spin and lattice structure of single-crystal SrFe2As2 , the parent compound of the FeAs-based superconductor (Sr,K)Fe2As2 . We find that SrFe2As2 exhibits an abrupt structural phase transition at 220 K, where the structure changes from tetragonal with lattice parameters c>a=b to orthorhombic with c>a>b . At almost the same temperature, Fe spins develop a collinear antiferromagnetic structure along the orthorhombic a axis with spin direction parallel to this a axis. These results are consistent with earlier work on the RFeAsO ( R=rare earth) families of materials and on BaFe2As2 , and therefore suggest that static antiferromagnetic order is ubiquitous for the parent compounds of these FeAs-based high-transition temperature superconductors.

Spin structure of nucleon in QCD: inclusive and exclusive processes

International Nuclear Information System (INIS)

Teryaev, O.V.

2001-01-01

There are two basically independent ways to describe the nucleon spin structure. One is related to quark and gluon spins and another one to their total angular momenta. The latter spin structure may be studied, in principle, in hard exclusive processes

Abrupt relaxation in high-spin molecules

International Nuclear Information System (INIS)

Chang, C.-R.; Cheng, T.C.

2000-01-01

Mean-field model suggests that the rate of resonant quantum tunneling in high-spin molecules is not only field-dependent but also time-dependent. The relaxation-assisted resonant tunneling in high-spin molecules produces an abrupt magnetization change during relaxation. When the applied field is very close to the resonant field, a time-dependent interaction field gradually shifts the energies of different collective spin states, and magnetization tunneling is observed as two energies of the spin states coincide

High-spin nuclear structure studies with radioactive ion beams

International Nuclear Information System (INIS)

Baktash, C.

1992-01-01

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), nuclear physicists 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=O pairing correlations. In this paper, the author reviews, 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, a list of the beam species, intensities and energies that are needed to fulfill these goals is presented. The paper concludes with a description of the experimental techniques and instrumentations that are required for these studies

Q2 dependence of the spin structure function in the resonance region

International Nuclear Information System (INIS)

Li, Z.; Li, Z.

1994-01-01

In this paper, we show what we can learn from the CEBAF experiments on spin-structure functions, and the transition from the Drell-Hearn-Gerasimov sum rule in the real photon limit to the spin-dependent sum rules in deep inelastic scattering, and how the asymmetry A 1 (x,Q 2 ) approaches the scaling limit in the resonance region. The spin structure function in the resonance region alone cannot determine the spin-dependent sum rule due to the kinematic restriction of the resonance region. The integral ∫ 0 1 {A 1 (x,Q 2 )F 2 (x,Q 2 )/2x[1+R(x,Q 2 )]}dx is estimated from Q 2 =0--2.5 GeV 2 . The result shows that there is a region where both contributions from the baryon resonances and the deep inelastic scattering are important; thus it provides important information on the high twist effects on the spin-dependent sum rule

Structure and thermal evolution of spinning-down neutron stars

International Nuclear Information System (INIS)

Negreiros, R.; Schramm, S.; Weber, F.

2011-01-01

In this paper we address the effects of spin-down on the cooling of neutron stars. During its evolution, stellar composition and structure might be substantially altered, as a result of spin-down and the consequent density increase. Since the timescale of cooling might be comparable to to that of the spin-evolution, the modifications to the structure/composition might have important effects on the thermal evolution of the object. We show that the direct Urca process might be delayed or supressed, when spin-down is taken into account. This leads to neutron stars with slow cooling, as opposed to enhanced cooling as would be the case if a "froze-in" structure and composition were considered. In conclusion we demonstrate that the inclusion of spin-down effects on the cooling of neutron stars have far-reaching implications for the interpretation of pulsars. (author)

Spin as a probe of hadron structure

International Nuclear Information System (INIS)

Ali, R.

1995-01-01

In this thesis, hadron structure was explored by studying three problems. In each case some underlying hard process, or a characteristic hard momentum, yielded important physical information such as structure and fragmentation functions describing hadrons. This provided a test of QCD predictions. In the first problem, spin dependent quark structure functions were estimated for nuclei. The multipole L=2 structure function, measurable in deeply inelastic scattering of unpolarized leptons off a polarized J > 1 nuclear target, is a good indicator of exotic quark gluon components in the nucleus. I estimated this structure function for two different classes of nuclei light nuclei describable in an independent particle model approach, as well as for heavy nuclei described by slowly rotating collective variables. In the second problem, spin dependent gluonic structure functions in a transversely polarized proton were identified and the classification according to twist was discussed. I found that there were two twist three transverse spin gluonic structure functions, called herein H1(x,Q2) and H2(x,Q2). Cross section formulae were calculated for a variety of polarization states, assuming a simple effective interaction for X2 production from gluon fusion. In the third, and final problem, the emphasis shifted from spin dependent structure functions of polarised hadrons to the formulation of an effective, low energy, field theory of s wave quarkonia, constituent heavy quarks, and gluons. and radiative transitions were shown to be easily recovered. The light-cone gluon momentum distribution at very small x was calculated and shown to be uniquely determined by the non relativistic wave function. I found that the emission of low momentum gluons made this process quite sensitive to assumptions about the binding energy of heavy quarks in quarkonia. This gauge invariant theory is extend able to p-wave quarkonia where the non locality of the meson state is enhanced by the

Measurement of the proton spin structure function g1p

International Nuclear Information System (INIS)

Pussieux, T.

1994-10-01

In order to check the Bjorken sum rule and confirm the EMC surprising conclusion on the spin structure of the proton, the measurement of the spin structure function of the proton has been performed by the Spin Muon Collaboration via the polarized muon nucleon deep inelastic scattering. The results of the 1993 run are presented within a kinematical range of 0.003 2 = 10 GeV 2 . The first moment of the polarized spin structure function g 1 p is found to be two standard deviations below the Ellis-Jaffe sum rule. Assuming SU(3) for hyperons β decays, the quark spin contribution to the proton spin is extracted. Combining all available data on proton, neutron and deuton, The Bjorken sum rule is confirmed within 10%. (author). 25 refs., 3 figs., 2 tabs

Unravelling the spin-state of solvated [Fe(bpp)2]2+ spin-crossover complexes: structure-function relationship.

Science.gov (United States)

Giménez-López, Maria Del Carmen; Clemente-León, Miguel; Giménez-Saiz, Carlos

2018-05-23

This paper reports firstly the syntheses, crystal structures, and thermal and magnetic properties of spin crossover salts of formulae [Fe(bpp)2]3[Cr(CN)6]2·13H2O (1) and [Fe(bpp)2][N(CN)2]2·H2O (2) (bpp = 2,6-bis(pyrazol-3-yl)pyridine) exhibiting hydrogen-bonded networks of low-spin [Fe(bpp)2]2+ complexes and [Cr(CN)6]3- or [N(CN)2]- anions, with solvent molecules located in the voids. Desolvation of 1 is accompanied by a complete low-spin (LS) to a high-spin (HS) transformation that becomes reversible after rehydration by exposing the sample to the humidity of air. The influence of the lattice water on the magnetic properties of spin-crossover [Fe(bpp)2]X2 complex salts has been documented. In most cases, it stabilises the LS state over the HS one. In other cases, it is rather the contrary. The second part of this paper is devoted to unravelling the reasons why the lattice solvent stabilises one form over the other through magneto-structural correlations of [Fe(bpp)2]2+ salts bearing anions with different charge/size ratios (Xn-). The [Fe(bpp)2]2+ stacking explaining these two different behaviours is correlated here with the composition of the second coordination sphere of the Fe centers and the ability of these anions to form hydrogen bonds and/or π-π stacking interactions between them or the bpp ligand.

Zero-Field Spin Structure and Spin Reorientations in Layered Organic Antiferromagnet, κ-(BEDT-TTF)2Cu[N(CN)2]Cl, with Dzyaloshinskii-Moriya Interaction

Science.gov (United States)

Ishikawa, Rui; Tsunakawa, Hitoshi; Oinuma, Kohsuke; Michimura, Shinji; Taniguchi, Hiromi; Satoh, Kazuhiko; Ishii, Yasuyuki; Okamoto, Hiroyuki

2018-06-01

Detailed magnetization measurements enabled us to claim that the layered organic insulator κ-(BEDT-TTF)2Cu[N(CN)2]Cl [BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene] with the Dzyaloshinskii-Moriya interaction has an antiferromagnetic spin structure with the easy axis being the crystallographic c-axis and the net canting moment parallel to the a-axis at zero magnetic field. This zero-field spin structure is significantly different from that proposed in the past studies. The assignment was achieved by arguments including a correction of the direction of the weak ferromagnetism, reinterpretations of magnetization behaviors, and reasoning based on known high-field spin structures. We suggest that only the contributions of the strong intralayer antiferromagnetic interaction, the moderately weak Dzyaloshinskii-Moriya interaction, and the very weak interlayer ferromagnetic interaction can realize this spin structure. On the basis of this model, characteristic magnetic-field dependences of the magnetization can be interpreted as consequences of intriguing spin reorientations. The first reorientation is an unusual spin-flop transition under a magnetic field parallel to the b-axis. Although the existence of this transition is already known, the interpretation of what happens at this transition has been significantly revised. We suggest that this transition can be regarded as a spin-flop phenomenon of the local canting moment. We also claim that half of the spins rotate by 180° at this transition, in contrast to the conventional spin flop transition. The second reorientation is the gradual rotation of the spins during the variation of the magnetic field parallel to the c-axis. In this process, all the spins rotate around the Dzyaloshinskii-Moriya vectors by 90°. The results of our simulation based on the classical spin model well reproduce these spin reorientation behaviors, which strongly support our claimed zero-field spin structure. The present study highlights the

The fabrication of highly uniform ZnO/CdS core/shell structures using a spin-coating-based successive ion layer adsorption and reaction method

International Nuclear Information System (INIS)

Joo, Jinmyoung; Kim, Darae; Yun, Dong-Jin; Jun, Hwichan; Rhee, Shi-Woo; Lee, Jae Sung; Yong, Kijung; Jeon, Sangmin; Kim, Sungjee

2010-01-01

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.

The fabrication of highly uniform ZnO/CdS core/shell structures using a spin-coating-based successive ion layer adsorption and reaction method

Energy Technology Data Exchange (ETDEWEB)

Joo, Jinmyoung; Kim, Darae; Yun, Dong-Jin; Jun, Hwichan; Rhee, Shi-Woo; Lee, Jae Sung; Yong, Kijung; Jeon, Sangmin [System on Chip Chemical Process Research, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of); Kim, Sungjee, E-mail: jeons@postech.ac.kr [Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of)

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.

IV. Workshop on High Energy Spin Physics

International Nuclear Information System (INIS)

Nurushev, S.

1992-01-01

In this proceedings the results on high energy spin physics are summarized. The theory of spin phenomenon and the experimental results at intermediate energy and at high energy spin physics and new technical developments in polarization experiments are presented

Measuring spin-dependent structure functions at CEBAF

International Nuclear Information System (INIS)

Schaefer, A.

1994-01-01

The author analyses whether CEBAF with a 10 GeV beam could contribute significantly to the understanding of spin-dependent deep-inelastic scattering as well as semi-inclusive reactions. The main advantage of CEBAF is the much better attainable statistics, its great disadvantage its comparably low energy, which limits the accessible x-range to about 0.15 to 0.7. Within these constraints CEBAF could provide (1) high precision data which would be very valuable to understand the Q 2 dependence of the spin-dependent structure functions g 1 (x) and G 2 (x) and (2) the by far most precise determination of the third moments of g 1 (x) and g 2 (x) the latter of which the author argues to be related to a fundamental property of the nucleon

Nuclear data for the high-spin community

Energy Technology Data Exchange (ETDEWEB)

Firestone, R B [Lawrence Berkeley Lab., CA (United States); Singh, B [McMaster Univ., Hamilton, ON (Canada). Tandem Accelerator Lab.

1992-08-01

The Isotopes Project at Berkeley is developing the Evaluated High-Spin Data File, a subset of the Evaluated Nuclear Structure Data File (ENSDF). The following products were under development at the time of the conference: eighth edition of the Table of Isotopes, electronic table of isotopes, data bases, nuclear charts, nuclear wallet cards, nuclear CD-ROM, FAX data services, on-line data services.

Shapes and alignments at high spin in some rare-earth nuclei

International Nuclear Information System (INIS)

Deleplanque, M.A.; Diamond, R.M.; Stephens, F.S.; Macchiavelli, A.O.; Doessing, T.; Draper, J.E.; Dines, E.L.

1985-01-01

The structure of nuclei at high spins is dominated by an interplay between deformation and alignment effects. Cranking models predict various shapes but at the highest spins, there is a tendency towards large triaxial deformations and sometimes towards very large prolate deformations (superdeformations). Directly involved in the shape changes are aligned orbitals which come down to the Fermi level as the nucleus rotates more rapidly. At a certain frequency, they become populated and cause large alignments. The mechanism of these changes has been explored by looking at a series of rare earth quasirotational nuclei from Dy to W in the transition region around N = 90 neutrons. The continuum spectra, corrected for incomplete population (feeding) of the high spins, are directly proportional to dynamic effective moments of inertia which describe how much spin is generated at each rotational frequency

Spin structure of the nucleon and polarization

International Nuclear Information System (INIS)

Prescott, C.Y.

1994-09-01

Recent experiments at CERN and SLAC have added new knowledge about the spin structure of the proton and the deuteron. A brief historical background is presented, the status of experiments is discussed, and progress in the understanding of the spin of the nucleon in the context of the quark parton model is summarized

High-field spin dynamics of antiferromagnetic quantum spin chains

DEFF Research Database (Denmark)

Enderle, M.; Regnault, L.P.; Broholm, C.

2000-01-01

present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights...

Spin Dynamics in Highly Spin Polarized Co1-xFexS2

Science.gov (United States)

Hoch, Michael J. R.; Kuhns, Philip L.; Moulton, William G.; Reyes, Arneil P.; Lu, Jun; Wang, Lan; Leighton, Chris

2006-09-01

Highly spin polarized or half-metallic systems are of considerable current interest because of their potential for spin injection in spintronics applications. The ferromagnet (FM) CoS2 is close to being a half-metal. Recent theoretical and experimental work has shown that the alloys Co1-xFexS2 (0.07 < x < 0.9) are highly spin polarized at low temperatures. The Fe concentration may be used to tune the spin polarization. Using 59Co FM- NMR we have investigated the spin dynamics in this family of alloys and have obtained information on the evolution of the d-band density of states at the Fermi level with x in the range 0 to 0.3. The results are compared with available theoretical predictions.

Toroidal high-spin isomers in the nucleus 304120

Science.gov (United States)

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

2017-05-01

Background: Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis with I =Iz . The toroidal high-K isomeric states at their local energy minima can be theoretically predicted using the cranked self-consistent Skyrme-Hartree-Fock method. Purpose: We use the cranked Skyrme-Hartree-Fock method to predict the properties of the toroidal high-spin isomers in the superheavy nucleus 120304184. Method: Our method consists of three steps: First, we use the deformation-constrained Skyrme-Hartree-Fock-Bogoliubov approach to search for the nuclear density distributions with toroidal shapes. Next, using these toroidal distributions as starting configurations, we apply an additional cranking constraint of a large angular momentum I =Iz about the symmetry z axis and search for the energy minima of the system as a function of the deformation. In the last step, if a local energy minimum with I =Iz is found, we perform at this point the cranked symmetry- and deformation-unconstrained Skyrme-Hartree-Fock calculations to locate a stable toroidal high-spin isomeric state in free convergence. Results: We have theoretically located two toroidal high-spin isomeric states of 120304184 with an angular momentum I =Iz=81 ℏ (proton 2p-2h, neutron 4p-4h excitation) and I =Iz=208 ℏ (proton 5p-5h, neutron 8p-8h) at the quadrupole moment deformations Q20=-297.7 b and Q20=-300.8 b with energies 79.2 and 101.6 MeV above the spherical ground state, respectively. The nuclear density distributions of the toroidal high-spin isomers 120304184(Iz=81 ℏ and 208 ℏ ) have the maximum density close to the nuclear matter density, 0.16 fm-3, and a torus major to minor radius aspect ratio R /d =3.25 . Conclusions: We demonstrate that aligned angular momenta of Iz=81 ℏ and 208 ℏ arising from

Spin fine structure of optically excited quantum dot molecules

Science.gov (United States)

Scheibner, M.; Doty, M. F.; Ponomarev, I. V.; Bracker, A. S.; Stinaff, E. A.; Korenev, V. L.; Reinecke, T. L.; Gammon, D.

2007-06-01

The interaction between spins in coupled quantum dots is revealed in distinct fine structure patterns in the measured optical spectra of InAs/GaAs double quantum dot molecules containing zero, one, or two excess holes. The fine structure is explained well in terms of a uniquely molecular interplay of spin-exchange interactions, Pauli exclusion, and orbital tunneling. This knowledge is critical for converting quantum dot molecule tunneling into a means of optically coupling not just orbitals but also spins.

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

International Nuclear Information System (INIS)

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 Kα and Kβ 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

Discovery of highly spin-polarized conducting surface states in the strong spin-orbit coupling semiconductor Sb2Se3

Science.gov (United States)

Das, Shekhar; Sirohi, Anshu; Kumar Gupta, Gaurav; Kamboj, Suman; Vasdev, Aastha; Gayen, Sirshendu; Guptasarma, Prasenjit; Das, Tanmoy; Sheet, Goutam

2018-06-01

Majority of the A2B3 -type chalcogenide systems with strong spin-orbit coupling (SOC), such as Bi2Se3,Bi2Te3 , and Sb2Te3 , etc., are topological insulators. One important exception is Sb2Se3 where a topological nontrivial phase was argued to be possible under ambient conditions, but such a phase could be detected to exist only under pressure. In this paper, we show that Sb2Se3 like Bi2Se3 displays a generation of highly spin-polarized current under mesoscopic superconducting point contacts as measured by point-contact Andreev reflection spectroscopy. In addition, we observe a large negative and anisotropic magnetoresistance of the mesoscopic metallic point contacts formed on Sb2Se3 . Our band-structure calculations confirm the trivial nature of Sb2Se3 crystals and reveal two trivial surface states one of which shows large spin splitting due to Rashba-type SOC. The observed high spin polarization and related phenomena in Sb2Se3 can be attributed to this spin splitting.

91Mo and 89Nb high-spin states

International Nuclear Information System (INIS)

Baktybaev, K.; Kojlyk, N.; Ramankulov, K.E.

2003-01-01

In the work the shell-model calculation for 91 Mo and 89 Nb nuclei high-spin states with several valente nucleons is worked out. The nucleons have been arranged in the {2p 1/2 1g 9 / 2 } configurations above the 88 Sr twice magic frame. Using of formalism of generalized quasi-spin with H=H 0 +H pp +H nn +H pn Hamiltonian in which H pp , H nn , H pn the residual nucleon interactions have being written through generalized quasi-spin operators. The obtained scheme well reproduces experimental data for examined nuclei up to 31/2 + , 33/2 - levels with seniority ν=3.5. Similarity of the spectroscopic structures of the nucleus levels with different protons and neutrons numbers above inert frame shows independence of nucleon-nucleon interactions from isotope spins of particles. There are analogous comparison of some negative yrast bands parity levels. The theory well transmits intensity values for electromagnet transitions between states. Besides the observed nuclei's properties does not give any indication on presence of valent nucleons collective motion in the both nuclei

Measuring spin-dependent structure functions at CEBAF

Energy Technology Data Exchange (ETDEWEB)

Schaefer, A. [Universitaet Frankfurt (Germany)

1994-04-01

The author analyses whether CEBAF with a 10 GeV beam could contribute significantly to the understanding of spin-dependent deep-inelastic scattering as well as semi-inclusive reactions. The main advantage of CEBAF is the much better attainable statistics, its great disadvantage its comparably low energy, which limits the accessible x-range to about 0.15 to 0.7. Within these constraints CEBAF could provide (1) high precision data which would be very valuable to understand the Q{sup 2} dependence of the spin-dependent structure functions g{sub 1}(x) and G{sub 2}(x) and (2) the by far most precise determination of the third moments of g{sub 1}(x) and g{sub 2}(x) the latter of which the author argues to be related to a fundamental property of the nucleon.

Observational signature of high spin at the Event Horizon Telescope

Science.gov (United States)

Gralla, Samuel E.; Lupsasca, Alexandru; Strominger, Andrew

2018-04-01

We analytically compute the observational appearance of an isotropically emitting point source on a circular, equatorial orbit near the horizon of a rapidly spinning black hole. The primary image moves on a vertical line segment, in contrast to the primarily horizontal motion of the spinless case. Secondary images, also on the vertical line, display a rich caustic structure. If detected, this unique signature could serve as a `smoking gun' for a high spin black hole in nature.

Spin-related transport phenomena in HgTe-based quantum well structures

International Nuclear Information System (INIS)

Koenig, Markus

2007-12-01

Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/Hg 0.3 Cd 0.7 Te quantum well structures. In our experiments, the existence of the quantum spin Hall (QSH) state was successfully demonstrated for the first time and the presented results provide clear evidence for the charge transport properties of the QSH state. Our experiments provide the first direct observation of the Aharonov-Casher (AC) effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSH relies on the peculiar band structure of the material and the existence of both the spin Hall effect and the AC effect is a consequence of the substantial spin-orbit interaction. (orig.)

Spin-related transport phenomena in HgTe-based quantum well structures

Energy Technology Data Exchange (ETDEWEB)

Koenig, Markus

2007-12-15

Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/Hg{sub 0.3}Cd{sub 0.7}Te quantum well structures. In our experiments, the existence of the quantum spin Hall (QSH) state was successfully demonstrated for the first time and the presented results provide clear evidence for the charge transport properties of the QSH state. Our experiments provide the first direct observation of the Aharonov-Casher (AC) effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSH relies on the peculiar band structure of the material and the existence of both the spin Hall effect and the AC effect is a consequence of the substantial spin-orbit interaction. (orig.)

Phenomena at very high spins

International Nuclear Information System (INIS)

Stephens, F.S.

1980-03-01

The present talk has three parts: first, a discussion of current ideas about the physics of very high spin states; second, some comments about noncollective behavior up to the highest spins where it is known, approx. 40 h; and finally, a presentation of the newest method for studying collective behavior up to spins of 60 to 70 h. The intention is that the overview presented in the first part will be sufficiently broad to indicate the relationship of the noncollective and collective behavior discussed in the other parts, and to provide some understanding of the compromise in behavior that seems to occur at the very highest spins. 13 figures

Probing spin-1 diquarks in deep inelastic structure functions

International Nuclear Information System (INIS)

Fredriksson, S.; Jaendel, M.; Larsson, T.

1983-01-01

Within the scope of a new diquark model for deep inelastic structure functions presented by us recently we use the existing data on F 1 sup(ep)(x,Q 2 ) to learn about the admixture of spin-1 diquarks in nucleons. It turns out that they are so rare, heavy and extended compared to spin-0 diquarks that they are presumably accidental and not dynamical. Their number and form factors can be understood qualitatively within this picture. Still, the spin-1 diquarks give interesting structures in data and, together with quarks and spin-0 diquarks, carry enough momentum to account for the full nucleon energy. A gluon component is hence not needed in the nucleon. (orig.)

Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures

Science.gov (United States)

Cho, Soonha; Baek, Seung-heon Chris; Lee, Kyeong-Dong; Jo, Younghun; Park, Byong-Guk

2015-01-01

The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques. PMID:26423608

Measuring the Neutron and 3He Spin Structure at Low Q2

International Nuclear Information System (INIS)

Vince Sulkosky

2005-01-01

The spin structure of the nucleon has been of great interest over the past few decades. Sum rules, including the Gerasimov-Drell-Hearn (GDH), and moments of the spin structure functions are powerful tools for understanding nucleon structure. The GDH sum rule, originally derived for real photon absorption, has been generalized to nonzero Q 2 . The goal of Jefferson Lab experiment E97-110 is to perform a precise measurement of the Q 2 dependence of the generalized GDH integral and of the moments of the neutron and 3 He spin structure functions between 0.02 and 0.3 GeV 2 . This Q 2 range will allow us to test predictions of Chiral Perturbation Theory, and verify the GDH sum rule by extrapolating the integral to the real photon point. The measurement will also contribute to the understanding of nucleon resonances. The data have been taken in Hall A using a high resolution spectrometer with the addition of a septum magnet, which allowed us to access the low Q 2 region. The analysis's status, prospects and impact will be discussed

An overview of recent nucleon spin structure measurements at Jefferson Lab

Energy Technology Data Exchange (ETDEWEB)

Allada, Kalyan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-02-01

Jefferson Lab have made significant contributions to improve our knowledge of the longitudinal spin structure by measuring polarized structure functions, g1 and g2, down to Q2 = 0.02 GeV2. The low Q2 data is especially useful in testing the Chiral Perturbation theory (cPT) calculations. The spin-dependent sum rules and the spin polarizabilities, constructed from the moments of g1 and g2, provide an important tool to study the longitudinal spin structure. We will present an overview of the experimental program to measure these structure functions at Jefferson Lab, and present some recent results on the neutron polarizabilities, proton g1 at low Q2, and proton and neutron d2 measurement. In addition to this, we will discuss the transverse spin structure of the nucleon which can be accessed using chiral-odd transversity distribution (h1), and show some results from measurements done on polarized 3He target in Hall A.

RosettaEPR: rotamer library for spin label structure and dynamics.

Directory of Open Access Journals (Sweden)

Nathan S Alexander

Full Text Available An increasingly used parameter in structural biology is the measurement of distances between spin labels bound to a protein. One limitation to these measurements is the unknown position of the spin label relative to the protein backbone. To overcome this drawback, we introduce a rotamer library of the methanethiosulfonate spin label (MTSSL into the protein modeling program Rosetta. Spin label rotamers were derived from conformations observed in crystal structures of spin labeled T4 lysozyme and previously published molecular dynamics simulations. Rosetta's ability to accurately recover spin label conformations and EPR measured distance distributions was evaluated against 19 experimentally determined MTSSL labeled structures of T4 lysozyme and the membrane protein LeuT and 73 distance distributions from T4 lysozyme and the membrane protein MsbA. For a site in the core of T4 lysozyme, the correct spin label conformation (Χ1 and Χ2 is recovered in 99.8% of trials. In surface positions 53% of the trajectories agree with crystallized conformations in Χ1 and Χ2. This level of recovery is on par with Rosetta performance for the 20 natural amino acids. In addition, Rosetta predicts the distance between two spin labels with a mean error of 4.4 Å. The width of the experimental distance distribution, which reflects the flexibility of the two spin labels, is predicted with a mean error of 1.3 Å. RosettaEPR makes full-atom spin label modeling available to a wide scientific community in conjunction with the powerful suite of modeling methods within Rosetta.

Physics of high spin nuclear states

Energy Technology Data Exchange (ETDEWEB)

Wyss, R [Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United States); [MSI, Frescativ, Stockholm (Sweden)

1992-08-01

High spin physics is a vast topic addressing the variety of nuclear excitation modes. In the present paper, some general aspects related to recent highlights of nuclear spectroscopy are discussed. The relation between signature splitting and shape changes in the unique parity orbitals is elucidated. The relevance of the Pseudo SU(3) symmetry in the understanding of rotational band structure is addressed. Specific features of rotational bands of intruder configurations are viewed as a probe of the neutron-proton interaction. (author). 36 refs., 5 figs.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Precision measurement of the neutron spin dependent structure functions

International Nuclear Information System (INIS)

Kolomensky, Y.G.

1997-02-01

In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g 1 n (x, Q 2 ) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized 3 He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 ≤ x ≤ 0.7 with an average Q 2 of 5 GeV 2 . The author reports the integral of the spin dependent structure function in the measured range to be ∫ 0.014 0.7 dx g 1 n (x, 5 GeV 2 ) = -0.036 ± 0.004(stat.) ± 0.005(syst.). The author observes relatively large values of g 1 n at low x that call into question the reliability of data extrapolation to x → 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g 1 p and g 1 n paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q 2 = 5 GeV 2 , determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule

Spin temperature concept verified by optical magnetometry of nuclear spins

Science.gov (United States)

Vladimirova, M.; Cronenberger, S.; Scalbert, D.; Ryzhov, I. I.; Zapasskii, V. S.; Kozlov, G. G.; Lemaître, A.; Kavokin, K. V.

2018-01-01

We develop a method of nonperturbative optical control over adiabatic remagnetization of the nuclear spin system and apply it to verify the spin temperature concept in GaAs microcavities. The nuclear spin system is shown to exactly follow the predictions of the spin temperature theory, despite the quadrupole interaction that was earlier reported to disrupt nuclear spin thermalization. These findings open a way for the deep cooling of nuclear spins in semiconductor structures, with the prospect of realizing nuclear spin-ordered states for high-fidelity spin-photon interfaces.

Engineering hybrid Co-picene structures with variable spin coupling

Energy Technology Data Exchange (ETDEWEB)

Zhou, Chunsheng [Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shan, Huan; Li, Bin, E-mail: libin@mail.ustc.edu.cn, E-mail: adzhao@ustc.edu.cn; Zhao, Aidi, E-mail: libin@mail.ustc.edu.cn, E-mail: adzhao@ustc.edu.cn; Wang, Bing [Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2016-04-25

We report on the in situ engineering of hybrid Co-picene magnetic structures with variable spin coupling using a low-temperature scanning tunneling microscope. Single picene molecules adsorbed on Au(111) are manipulated to accommodate individual Co atoms one by one, forming stable artificial hybrid structures with magnetism introduced by the Co atoms. By monitoring the evolution of the Kondo effect at each site of Co atom, we found that the picene molecule plays an important role in tuning the spin coupling between individual Co atoms, which is confirmed by theoretical calculations based on the density-functional theory. Our findings indicate that the hybrid metal-molecule structures with variable spin coupling on surfaces can be artificially constructed in a controlled manner.

Identification of high-spin states in 235U

International Nuclear Information System (INIS)

Lorenz, A.; Makarenko, V.E.; Chukreev, F.E.

1994-02-01

The results of a 235 U high spin states study are analysed. A new way to assign newly observed gamma ray transitions is proposed. Such assignments deals with low spin parts of the level scheme without introducing high spin level states. (author)

Measurement of the spin dependent structure functions of proton and neutron

International Nuclear Information System (INIS)

Rith, K.

1989-01-01

Recent results from the EMC experiment on the spin dependent structure function g 1 p (x) of the proton are discussed. They suggest that the nucleon spin does not originate from quark spins but rather from angular orbital momentum and gluon contributions. A proposed experiment at HERA is presented which will allow a very accurate measurement of the spin dependent structure functions and their integrals of both proton and neutron and a precise test of the Bjorken sum rule. (orig.)

Spin-polarized SEM

International Nuclear Information System (INIS)

Konoto, Makoto

2007-01-01

Development of highly effective evaluation technology of magnetic structures on a nanometric scale is a key to understanding spintronics and related phenomena. A high-resolution spin-polarized scanning electron microscope (spin SEM) developed recently is quite suitable for probing such nanostructures because of the capability of analyzing local magnetization vectors in three dimensions. Utilizing the spin SEM, a layered antiferromagnetic structure with the 1nm-alternation of bilayer-sheet magnetization has been successfully resolved. The real-space imaging with full analysis of the temperature-dependent magnetization vectors will be demonstrated. (author)

The Electronic Structure Signature of the Spin Cross-Over Transition of [Co(dpzca)2

Science.gov (United States)

Zhang, Xin; Mu, Sai; Liu, Yang; Luo, Jian; Zhang, Jian; N'Diaye, Alpha T.; Enders, Axel; Dowben, Peter A.

2018-05-01

The unoccupied electronic structure of the spin crossover molecule cobalt (II) N-(2-pyrazylcarbonyl)-2-pyrazinecarboxamide, [Co(dpzca)2] was investigated, using X-ray absorption spectroscopy (XAS) and compared with magnetometry (SQUID) measurements. The temperature dependence of the XAS and molecular magnetic susceptibility χmT are in general agreement for [Co(dpzca)2], and consistent with density functional theory (DFT). This agreement of magnetic susceptibility and X-ray absorption spectroscopy provides strong evidence that the changes in magnetic moment can be ascribed to changes in electronic structure. Calculations show the choice of Coulomb correlation energy U has a profound effect on the electronic structure of the low spin state, but has little influence on the electronic structure of the high spin state. In the temperature dependence of the XAS, there is also evidence of an X-ray induced excited state trapping for [Co(dpzca)2] at 15 K.

Spin effects in high energy quark-quark scattering

International Nuclear Information System (INIS)

Goloskokov, S.V.; Selyugin, O.V.

1993-01-01

The spin amplitudes in high-energy quark-quark scattering at /t/>1 GeV 2 are analyzed. It is shown that the gluon contributions in the QCDα s 3 order lead to the spin-flip amplitude growing as s. This means the existence of the spin-flip part in pomeron exchange. The resulting T f is about few per cent of the spin-non-flip contribution. The factorization of the large-distance and high-energy effects in the spin-flip amplitude is obtained. 13 refs.; 2 figs.; 1 tab

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

Science.gov (United States)

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.

Spin-resolved magnetic studies of focused ion beam etched nano-sized magnetic structures

International Nuclear Information System (INIS)

Li Jian; Rau, Carl

2005-01-01

Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We report on new, spin-resolved magnetic microstructures, such as magnetic 'C' states and magnetic vortices, found at surfaces of FIB patterned magnetic elements. It is found that FIB milling has a negligible effect on surface magnetic domain and domain wall structures. It is demonstrated that SIMPA can evolve into an important and efficient tool to study magnetic domain, domain wall and other structures as well as to perform magnetic depth profiling of magnetic nano-systems to be used in ultra-high density magnetic recording and in magnetic sensors

Masses, magnetic moments, QCD and proton spin structure

International Nuclear Information System (INIS)

Lipkin, H.J.

1990-10-01

This talk is dedicated to the memory of Andrei D. Sakharov. In addition to his well-known contributions to society, Sakharov was also a pioneer in spin physics and the application of the basic ideas of QCD to spin structure of hadrons. He took quarks seriously at the time when the particle physicists ridiculed the quark model. Immediately after the quark proposal Sakharov asked: 'Why is M Λ ≠ M Σ ? They contain the same quarks' His answer was 'Spin Physics! A flavor-dependent hyperfine interaction'. (author)

Decay of the high-spin isomer in 160Re: Changing single-particle structure beyond the proton drip line

International Nuclear Information System (INIS)

Darby, I.G.; Page, R.D.; Joss, D.T.; Simpson, J.; Bianco, L.; Cooper, R.J.; Eeckhaudt, S.; Ertuerk, S.; Gall, B.; Grahn, T.; Greenlees, P.T.; Hadinia, B.; Jones, P.M.; Judson, D.S.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Leppaenen, A.-P.; Nyman, M.

2011-01-01

A new high-spin isomeric state (t 1/2 =2.8±0.1 μs) in 160 Re has been identified. This high-spin isomer is unique in that it only decays by γ-decay and not by proton or α-particle emission as is the case in every other proton emitter between Z=64 and 80. Shell model calculations indicate how the convergence of the h 9/2 and f 7/2 neutron levels in this region could open up a γ-decay path from the high-spin isomer to the low-spin ground state of 160 Re, providing a natural explanation for this anomalous absence of charged-particle emission. The consequences of these observations for future searches for proton emission from even more exotic nuclei and in-beam spectroscopic studies are considered.

Changing the cubic ferrimagnetic domain structure in temperature region of spin flip transition

International Nuclear Information System (INIS)

Djuraev, D.R.; Niyazov, L.N.; Saidov, K.S.; Sokolov, B.Yu.

2011-01-01

The transformation of cubic ferrimagnetic Tb 0.2 Y 2.8 Fe 5 O 12 domain structure has been studied by magneto optic method in the temperature region of spontaneous spin flip phase transition (SPT). It has been found that SPT occurs in a finite temperature interval where the coexistence of low- and high- temperature magnetic phase domains has observed. A character of domain structure evolution in temperature region of spin flip essentially depends on the presence of mechanical stresses in crystal. Interpretation of experimental results has been carried out within the framework of SPT theory for a cubic crystal. (authors)

High energy spin isospin modes in nuclei

International Nuclear Information System (INIS)

Chanfray, G.; Ericson, M.

1984-01-01

The high energy response of nuclei to a spin-isospin excitation is investigated. We show the existence of a strong contrast between the spin transverse and spin longitudinal responses. The second one undergoes a shadow effect in the Δ region and displays the occurrence of the pionic branch

Spin splitting in band structures of BiTeX (X=Cl, Br, I) monolayers

Science.gov (United States)

Hvazdouski, D. C.; Baranava, M. S.; Stempitsky, V. R.

2018-04-01

In systems with breaking of inversion symmetry a perpendicular electric field arises that interacts with the conduction electrons. It may give rise to electron state splitting even without influence of external magnetic field due to the spin-orbital interaction (SOI). Such a removal of the spin degeneracy is called the Rashba effect. Nanostructure with the Rashba effect can be part of a spin transistor. Spin degeneracy can be realized in a channel from a material of this type without additive of magnetic ions. Lack of additive increases the charge carrier mobility and reliability of the device. Ab initio simulations of BiTeX (X=Cl, Br, I) monolayers have been carried out using VASP wherein implemented DFT method. The study of this structures is of interest because such sort of structures can be used their as spin-orbitronics materials. The crystal parameters of BiTeCl, BiTeBr, BiTeI have been determined by the ionic relaxation and static calculations. It is necessary to note that splitting of energy bands occurs in case of SOI included. The values of the Rashba coefficient aR (in the range from 6.25 to 10.00 eV·Å) have high magnitudes for spintronics materials. Band structure of monolayers structures have ideal Rashba electron gas, i.e. there no other energy states near to Fermi level except Rashba states.

Electromagnetic properties of nuclei at high spins

International Nuclear Information System (INIS)

Leander, G.A.

1986-01-01

A photon emitted by an excited state is likely to carry away, at most, 1 or 2 h-bar of angular momentum. Therefore, a profusion of photons is needed to deexcite the rapidly rotating states of nuclei formed by heavy-ion reactions. The study of electromagnetic properties has become the primary source of information on nuclear structure at high spins and, also, at the warm temperatures present in the initial stage of the electromagnetic cascade process. The purpose of this paper is a review of the E1, M1, and E2 properties of such highly excited states. 42 refs., 5 figs

/sup 13/C-/sup 13/C spin-spin coupling constants in structural investigations. II. Conformational structure of vinyl ethers

Energy Technology Data Exchange (ETDEWEB)

Krivdin, L.B.; Shcherbakov, V.V.; Bzhezovskii, V.M.; Kalabin, G.A.

1986-10-10

The /sup 13/C-/sup 13/C spin-spin coupling constants between the carbon nuclei of the vinyl group were measured for a series of vinyl ethers. It was established that the unshared electron pairs of the oxygen atom can make a substantial stereospecific contribution to the direct /sup 13/C-/sup 13/C constants of the adjacent nuclei. The observed effect was used to establish the conformational structure of the compounds.

Spin-torsion effects in the hyperfine structure of methanol

International Nuclear Information System (INIS)

Coudert, L. H.; Gutlé, C.; Huet, T. R.; Grabow, J.-U.; Levshakov, S. A.

2015-01-01

The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling

Geometrical spin symmetry and spin

International Nuclear Information System (INIS)

Pestov, I. B.

2011-01-01

Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

Experimental investigation shell model excitations of 89Zr up to high spin and its comparison with 88,90Zr

International Nuclear Information System (INIS)

Saha, S.; Palit, R.; Sethi, J.

2012-01-01

The excited states of nuclei near N=50 closed shell provide suitable laboratory for testing the interactions of shell model states, possible presence of high spin isomers and help in understanding the shape transition as the higher orbitals are occupied. In particular, the structure of N = 49 isotones (and Z =32 to 46) with one hole in N=50 shell gap have been investigated using different reactions. Interestingly, the high spin states in these isotones have contribution from particle excitations across the respective proton and neutron shell gaps and provide suitable testing ground for the prediction of shell model interactions describing theses excitations across the shell gap. In the literature, extensive study of the high spin states of heavier N = 49 isotones starting with 91 Mo up to 95 Pd are available. Limited information existed on the high spin states of lighter isotones. Therefore, the motivation of the present work is to extend the high spin structure of 89 Zr and to characterize the structure of these levels through comparison with the large scale shell model calculations based on two new residual interactions in f 5/2 pg 9/2 model space

Spin transport in nanowires

OpenAIRE

Pramanik, S.; bandyopadhyay, S.; Cahay, M.

2003-01-01

We study high-field spin transport of electrons in a quasi one-dimensional channel of a $GaAs$ gate controlled spin interferometer (SPINFET) using a semiclassical formalism (spin density matrix evolution coupled with Boltzmann transport equation). Spin dephasing (or depolarization) is predominantly caused by D'yakonov-Perel' relaxation associated with momentum dependent spin orbit coupling effects that arise due to bulk inversion asymmetry (Dresselhaus spin orbit coupling) and structural inve...

Using spin to probe hadronic structure

International Nuclear Information System (INIS)

Ramsey, G.P.; Argonne National Lab., IL

1994-01-01

The theoretical and experimental status of high energy spin phenomena is summarized, with emphasis on the spin properties of nucleons. It is stressed that crucial tests of the Standard Model can be made with polarization experiments. By performing the experiments discussed here, the authors will reveal important constituent and composite properties of protons and neutrons. The future prospects for planned polarization experiments are discussed

High spin levels in 62Zn, 64Zn, 66Zn, and 68Zn

International Nuclear Information System (INIS)

Bruandet, J.-F.

1976-01-01

Investigation by in-beam gamma spectroscopy of high-spin states in the even zinc isotopes has been made using the Ni(α,2nγ)Zn reactions at Esub(α) approximately equal to 30MeV for 62 Zn, 64 Zn and 66 Zn, and the 65 Cu(α,pγ) reaction at Esub(α) approximately equal to 18MeV for 68 Zn. The high-spin states feeding by varying the incident particles: p, 3 He,α, 12 C is discussed. It is pointed out that the gsub(9/2) orbital plays an important role in the structure of the high-spin states. The variation of the inertia momentum throughout the yrast line shows a backbending behavior and a shape transition associated to the occurence, for J>6, of rotational states is speculated [fr

High-spin research with HERA [High Energy-Resolution Array

International Nuclear Information System (INIS)

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

Spin-polarized scanning electron microscopy

International Nuclear Information System (INIS)

Kohashi, Teruo

2014-01-01

Spin-Polarized Scanning Electron Microscopy (Spin SEM) is one way for observing magnetic domain structures taking advantage of the spin polarization of the secondary electrons emitted from a ferromagnetic sample. This principle brings us several excellent capabilities such as high-spatial resolution better than 10 nm, and analysis of magnetization direction in three dimensions. In this paper, the principle and the structure of the spin SEM is briefly introduced, and some examples of the spin SEM measurements are shown. (author)

High-Spin Structure in Odd-Odd 160Lu Nucleus

International Nuclear Information System (INIS)

Wang Lie-Lin; Lu Jing-Bin; Yang Dong; Ma Ke-Yan; Yin Li-Chang; Zhou Yin-Hang; Wu Xiao-Guang; Wen Shu-Xian; Li Guang-Sheng; Yang Chun-Xiang

2012-01-01

The high-spin states of 160 Lu are populated by the fusion-evaporation reaction 144 Sm( 19 F,3n) 160 Lu at beam energies of 90 and 106 MeV. A new level scheme of 160 Lu is established. A possible isomeric state based on the πh 11/2 νh 9/2 configuration is observed. The new decoupled band with the configuration of πd 3/2 [411]1/2 + νi 13/2 [660]1/2 + is established, and the configurations of these similar decoupled bands in the neighboring odd-odd 162−166 Lu nuclei are suggested. A positive parity coupled band is assigned as the πd 5/2 [402]5/2 + νi 13/2 [660]1/2 + configuration. (nuclear physics)

Reduction of shunt current in buffer-free IrMn based spin-valve structures

Science.gov (United States)

Kocaman, B.; Akdoğan, N.

2018-06-01

The presence of thick buffer layers in magnetic sensor devices decreases sensor sensitivity due to shunt currents. With this motivation, we produced IrMn-based spin-valve multilayers without using buffer layer. We also studied the effects of post-annealing and IrMn thickness on exchange bias field (HEB) and blocking temperature (TB) of the system. Magnetization measurements indicate that both HEB and TB values are significantly enhanced with post-annealing of IrMn layer. In addition, we report that IrMn thickness of the system strongly influences the magnetization and transport characteristics of the spin-valve structures. We found that the minimum thickness of IrMn layer is 6 nm in order to achieve the lowest shunt current and high blocking temperature (>300 K). We also investigated the training of exchange bias to check the long-term durability of IrMn-based spin-valve structures for device applications.

The magnetoresistive effect induced by stress in spin-valve structures

International Nuclear Information System (INIS)

Li-Jie, Qian; Xiao-Yong, Xu; Jing-Guo, Hu

2009-01-01

Using a method of free energy minimization, this paper investigates the magnetization properties of a ferromagnetic (FM) monolayer and an FM/antiferromagnetic (AFM) bilayer under a stress field, respectively. It then investigates the magnetoresistance (MR) of the spin-valve structure, which is built by an FM monolayer and an FM/AFM bilayer, and its dependence upon the applied stress field. The results show that under the stress field, the magnetization properties of the FM monolayer is obviously different from that of the FM/AFM bilayer, since the coupled AFM layer can obviously block the magnetization of the FM layer. This phenomenon makes the MR of the spin-valve structure become obvious. In detail, there are two behaviors for the MR of the spin-valve structure dependence upon the stress field distinguished by the coupling (FM coupling or AFM coupling) between the FM layer and the FM/AFM bilayer. Either behavior of the MR of the spin-valve structure depends on the stress field including its value and orientation. Based on these investigations, a perfect mechanical sensor at the nano-scale is suggested to be devised experimentally

Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation

Energy Technology Data Exchange (ETDEWEB)

Plötzing, M.; Adam, R., E-mail: r.adam@fz-juelich.de; Weier, C.; Plucinski, L.; Schneider, C. M. [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425 Jülich (Germany); Eich, S.; Emmerich, S.; Rollinger, M.; Aeschlimann, M. [University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern (Germany); Mathias, S. [Georg-August-Universität Göttingen, I. Physikalisches Institut, 37077 Göttingen (Germany)

2016-04-15

The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.

Experimental status of high-spin states

International Nuclear Information System (INIS)

Stephens, F.S.

1975-09-01

Changes occurring in high spin nuclear states are discussed. Experimental methods for studying reduction and eventual quenching of pairing interactions, changes in nuclear shapes, and alignment of individual particle angular momenta with increasing spin are reviewed. Emphasis is placed on the study of continuum gamma rays following heavy ion reactions. (12 figures)

Spin-dependent transport properties of a GaMnAs-based vertical spin metal-oxide-semiconductor field-effect transistor structure

Energy Technology Data Exchange (ETDEWEB)

Kanaki, Toshiki, E-mail: kanaki@cryst.t.u-tokyo.ac.jp; Asahara, Hirokatsu; Ohya, Shinobu, E-mail: ohya@cryst.t.u-tokyo.ac.jp; Tanaka, Masaaki, E-mail: masaaki@ee.t.u-tokyo.ac.jp [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2015-12-14

We fabricate a vertical spin metal-oxide-semiconductor field-effect transistor (spin-MOSFET) structure, which is composed of an epitaxial single-crystal heterostructure with a ferromagnetic-semiconductor GaMnAs source/drain, and investigate its spin-dependent transport properties. We modulate the drain-source current I{sub DS} by ∼±0.5% with a gate-source voltage of ±10.8 V and also modulate I{sub DS} by up to 60% with changing the magnetization configuration of the GaMnAs source/drain at 3.5 K. The magnetoresistance ratio is more than two orders of magnitude higher than that obtained in the previous studies on spin MOSFETs. Our result shows that a vertical structure is one of the hopeful candidates for spin MOSFET when the device size is reduced to a sub-micron or nanometer scale.

Spin-dependent transport properties of a GaMnAs-based vertical spin metal-oxide-semiconductor field-effect transistor structure

International Nuclear Information System (INIS)

Kanaki, Toshiki; Asahara, Hirokatsu; Ohya, Shinobu; Tanaka, Masaaki

2015-01-01

We fabricate a vertical spin metal-oxide-semiconductor field-effect transistor (spin-MOSFET) structure, which is composed of an epitaxial single-crystal heterostructure with a ferromagnetic-semiconductor GaMnAs source/drain, and investigate its spin-dependent transport properties. We modulate the drain-source current I DS by ∼±0.5% with a gate-source voltage of ±10.8 V and also modulate I DS by up to 60% with changing the magnetization configuration of the GaMnAs source/drain at 3.5 K. The magnetoresistance ratio is more than two orders of magnitude higher than that obtained in the previous studies on spin MOSFETs. Our result shows that a vertical structure is one of the hopeful candidates for spin MOSFET when the device size is reduced to a sub-micron or nanometer scale

Spin current and electrical polarization in GaN double-barrier structures

OpenAIRE

Litvinov, V. I.

2007-01-01

Tunnel spin polarization in a piezoelectric AlGaN/GaN double barrier structure is calculated. It is shown that the piezoelectric field and the spontaneous electrical polarization increase an efficiency of the tunnel spin injection. The relation between the electrical polarization and the spin orientation allows engineering a zero magnetic field spin injection manipulating the lattice-mismatch strain with an Al-content in the barriers.

Yrast and high spin states in 22Ne

International Nuclear Information System (INIS)

Szanto, E.M.; Toledo, A.S. de

1982-08-01

High spin states in 22 Ne have been investigated by the reactions 11 B( 13 C,d) 22 Ne and 13 C( 11 B,d) 22 Ne up to E* approximately=19 MeV. Yrast states were observed at 11.02 MeV (8 + ) and 15.46 MeV (10 + ) excitation energy. A backbending in 22 Ne is observed around spin 8 + . The location of high spin states I [pt

Sum rule measurements of the spin-dependent compton amplitude (nucleon spin structure at Q2 = 0)

International Nuclear Information System (INIS)

Babusci, D.; Giordano, G.; Baghaei, H.; Cichocki, A.; Blecher, M.; Breuer, M.; Commeaux, C.; Didelez, J.P.; Caracappa, A.; Fan, Q.

1995-01-01

Energy weighted integrals of the difference in helicity-dependent photo-production cross sections (σ 1/2 - σ 3/2 ) provide information on the nucleon's Spin-dependent Polarizability (γ), and on the spin-dependent part of the asymptotic forward Compton amplitude through the Drell-Hearn-Gerasimov (DHG) sum rule. (The latter forms the Q 2 =0 limit of recent spin-asymmetry experiments in deep-inelastic lepton-scattering.) There are no direct measurements of σ 1/2 or σ 3/2 , for either the proton or the neutron. Estimates from current π-photo-production multipole analyses, particularly for the proton-neutron difference, are in good agreement with relativistic-l-loop Chiral calculations (χPT) for γ but predict large deviations from the DHG sum rule. Either (a) both the 2-loop corrections to the Spin-Polarizability are large and the existing multipoles are wrong, or (b) modifications to the Drell-Hearn-Gerasimov sum rule are required to fully describe the isospin structure of the nucleon. The helicity-dependent photo-reaction amplitudes, for both the proton and the neutron, will be measured at LEGS from pion-threshold to 470 MeV. In these double-polarization experiments, circularly polarized photons from LEGS will be used with SPHICE, a new frozen-spin target consisting of rvec H · rvec D in the solid phase. Reaction channels will be identified in SASY, a large detector array covering about 80% of 4π. A high degree of symmetry in both target and detector will be used to minimize systematic uncertainties

Fractional vortex lattice structures in spin-triplet superconductors

International Nuclear Information System (INIS)

Chung, Suk Bum; Agterberg, Daniel F; Kim, Eun-A

2009-01-01

Motivated by recent interest in spin-triplet superconductors, we investigate the vortex lattice structures for this class of unconventional superconductors. We discuss how the order parameter symmetry can give rise to U(1)xU(1) symmetry in the same sense as in spinor condensates, making half-quantum vortices (HQVs) topologically stable. We then calculate the vortex lattice structure of HQVs, with particular attention on the roles of the crystalline lattice, the Zeeman coupling and Meissner screening, all absent in spinor condensates. Finally, we consider how spin-orbit coupling leads to a breakdown of the U(1)xU(1) symmetry in free energy and whether the HQV lattice survives this symmetry breaking. As examples, we examine simpler spin-triplet models proposed in the context of Na x CoO 2 ·yH 2 O and Bechgaard salts, as well as the better known and more complex model for Sr 2 RuO 4 .

Max Auwaerter symposium: spin mapping and spin manipulation on the atomic scale

International Nuclear Information System (INIS)

Wiesendanger, R.

2008-01-01

Full text: A fundamental understanding of magnetic and spin-dependent phenomena requires the determination of spin structures and spin excitations down to the atomic scale. The direct visualization of atomic-scale spin structures has first been accomplished for magnetic metals by combining the atomic resolution capability of Scanning Tunnelling Microscopy (STM) with spin sensitivity, based on vacuum tunnelling of spin-polarized electrons. The resulting technique, Spin-Polarized Scanning Tunnelling Microscopy (SP-STM), nowadays provides unprecedented insight into collinear and non-collinear spin structures at surfaces of magnetic nanostructures and has already led to the discovery of new types of magnetic order at the nanoscale. More recently, the development of subkelvin SP-STM has allowed studies of ground-state magnetic properties of individual magnetic adatoms on non-magnetic substrates as well as the magnetic interactions between them. Based on SP-STM experiments performed at temperatures of 300 mK, indirect magnetic exchange interactions at the sub-milli-electronvolt energy scale between individual paramagnetic adatoms as well as between adatoms and nearby magnetic nanostructures could directly be revealed in real space up to distances of several nanometers. In both cases we have observed an oscillatory behavior of the magnetic exchange coupling, alternating between ferromagnetic and antiferromagnetic, as a function of distance. Moreover, the detection of spin-dependent exchange and correlation forces has allowed a first direct real-space observation of spin structures at surfaces of antiferromagnetic insulators. This new type of scanning probe microscopy, called Magnetic Exchange Force Microscopy (MExFM), offers a powerful new tool to investigate different types of spin-spin interactions based on direct-, super-, or RKKY-type exchange down to the atomic level. By combining MExFM with high-precision measurements of damping forces, localized or confined spin

Quark-hadron duality of nucleon spin structure function

International Nuclear Information System (INIS)

Dong, Y.B.

2005-01-01

Bloom-Gilman quark-hadron duality of nuclear spin structure function is studied by comparing the integral of g 1 from perturbative QCD prediction in the scaling region to the moment of g 1 in the resonance region. The spin structure function in the resonance region is estimated by the parametrization forms of non-resonance background and of resonance contributions. The uncertainties of our calculations due to those parametrization forms are discussed. Moreover, the effect of the Δ(1232)-resonance in the first resonance region and the role of the resonances in the second resonance region are explicitly shown. Elastic peak contribution to the duality is also analyzed. (orig.)

Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering

International Nuclear Information System (INIS)

Wislicki, W.

1998-01-01

We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g 1 p (x) and g 1 d (x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.003 2 >=10 GeV 2 . Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g 1 (x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world

High spin {gamma}-ray spectroscopy of {sup 121,122}Xe

Energy Technology Data Exchange (ETDEWEB)

Timmers, H [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.; [Department of Physics, SUNY at Stony Brook, NY (United States); Riley, M A; Hanna, F; Mullins, S M; Sharpey-Schafer, J F [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.; Hughes, J R; Fossan, D B; Liang, Y; Ma, R; Xu, N [Department of Physics, SUNY at Stony Brook, NY (United States); Simpson, J; Bentley, M A [Daresbury Lab. (United Kingdom); Bengtsson, T [Lund Univ. (Sweden). Dept. of Mathematical Physics; Wyss, R [Institute for Heavy Ion Research, Oak Ridge, TN (United States)

1992-08-01

High-spin states have been populated in {sup 121,122}Xe using the reactions {sup 108}Pd({sup 16}O,3n){sup 121}Xe at 65 MeV and {sup 96}Zr({sup 30}Si,4n/5n){sup 122}Xe/{sup 121}Xe at 135 MeV. Coincident {gamma} rays following the neutron evaporation were detected by six Compton-suppressed Ge detectors and the TESSA3 array respectively. The level structure of {sup 121}Xe and {sup 122}Xe has been extended up to 47/2 {Dirac_h} and 32 {Dirac_h} respectively. In {sup 121}Xe a coupled band was found feeding the 19/2{sup -} level. In {sup 122}Xe several decays are suggested to be a sequence of stretched E2 quadrupole transitions connecting states of positive parity. While in {sup 121}Xe this phenomenon was not observed, at high spin a phase transition from prolate collective rotation to oblate single particle excitation was detected in {sup 122}Xe. For the new, probably positive parity side band in{sup 122}Xe a four quasi-neutron or a two quasi-proton configuration of h{sub 11/2} quasi-nucleons might be considered. The positive parity high spin structure in {sup 122}Xe contains three I{sup {pi}} = 22{sup +} states of different character. This is predicted by TRS (total Routhian surface) calculations, which identify these states as two shapes with predominantly prolate collective characteristic and the third as an oblate single particle configuration. 12 refs., 3 figs.

Polarization-dependent pump-probe studies in atomic fine-structure levels: towards the production of spin-polarized electrons

International Nuclear Information System (INIS)

Sokell, E.; Zamith, S.; Bouchene, M.A.; Girard, B.

2000-01-01

The precession of orbital and spin angular momentum vectors has been observed in a pump-probe study of the 4P fine-structure states of atomic potassium. A femtosecond pump pulse prepared a coherent superposition of the two fine-structure components. A time-delayed probe pulse then ionized the system after it had been allowed to evolve freely. Oscillations recorded in the ion signal reflect the evolution of the orientation of the orbital and spin angular momentum due to spin-orbit coupling. This interpretation gives physical insight into the cause of the half-period phase shift observed when the relative polarizations of the laser pulses were changed from parallel to perpendicular. Finally, it is shown that these changes in the orientation of the spin momentum vector of the system can be utilized to produce highly spin-polarized free electrons on the femtosecond scale. (author)

Spin Hall Effect in Doped Semiconductor Structures

Science.gov (United States)

Tse, Wang-Kong; Das Sarma, Sankar

2006-03-01

We present a microscopic theory of the extrinsic spin Hall effect based on the diagrammatic perturbation theory. Side-jump (SJ) and skew-scattering (SS) contributions are explicitly taken into account to calculate the spin Hall conductivity, and we show their effects scale as σxy^SJ/σxy^SS ˜(/τ)/ɛF, where τ being the transport relaxation time. Motivated by recent experimental work we apply our theory to n-doped and p-doped 3D and 2D GaAs structures, obtaining analytical formulas for the SJ and SS contributions. Moreover, the ratio of the spin Hall conductivity to longitudinal conductivity is found as σs/σc˜10-3-10-4, in reasonable agreement with the recent experimental results of Kato et al. [Science 306, 1910 (2004)] in n-doped 3D GaAs system.

The Spin Structure of the Neutron Determined Using a Polarized He-3 Target

Energy Technology Data Exchange (ETDEWEB)

Middleton, H

2004-01-06

Described is a study of the internal spin structure of the neutron performed by measuring the asymmetry in spin-dependent deep inelastic scattering of polarized electrons from nuclear polarized {sup 3}He. Stanford Linear Accelerator experiment E142's sample of 400 million scattering events collected at beam energies between 19 and 26 GeV led to the most precise measurement of a nucleon spin structure function to date. The {sup 3}He target represents a major advance in polarized target technology, using the technique of spin exchange with optically pumped rubidium vapor to produce a typical {sup 3}He nuclear polarization of 34% in a 30cm long target cell with a gas density of 2.3 x 10{sup 20} cm{sup -3}. The target polarization was measured to {+-}7% using an Adiabatic Fast Passage NMR system calibrated with the thermal equilibrium polarization of the protons in a sample of water. The relatively high polarization and target thickness were the result of the development of large volume glass target cells which had inherent nuclear spin relaxation times for the {sup 3}He gas of as long as 70 hours. A target cell production procedure is presented which focuses on special glass blowing techniques to minimize surface interactions with the {sup 3}He nuclei and careful gas purification and vacuum system procedures to reduce relaxation inducing impurities.

QCD SPIN PHYSICS IN HADRONIC INTERACTIONS.

Energy Technology Data Exchange (ETDEWEB)

VOGELSANG,W.

2007-06-19

We discuss spin phenomena in high-energy hadronic scattering, with a particular emphasis on the spin physics program now underway at the first polarized proton-proton collider, RHIC. Experiments at RHIC unravel the spin structure of the nucleon in new ways. Prime goals are to determine the contribution of gluon spins to the proton spin, to elucidate the flavor structure of quark and antiquark polarizations in the nucleon, and to help clarify the origin of transverse-spin phenomena in QCD. These lectures describe some aspects of this program and of the associated physics.

Nanoscale spin-dependent transport of electrons and holes in Si-ferromagnet structures

NARCIS (Netherlands)

Ul Haq, E.

Given the rapid development of magnetic data storage and spin-electronics into the realm of nanotechnology, the understanding of the spin-dependent electronic transport and switching behavior of magnetic structures at the nanoscale is an important issue. We have developed spin-sensitive techniques

Spin Funneling for Enhanced Spin Injection into Ferromagnets

Science.gov (United States)

Sayed, Shehrin; Diep, Vinh Q.; Camsari, Kerem Yunus; Datta, Supriyo

2016-07-01

It is well-established that high spin-orbit coupling (SOC) materials convert a charge current density into a spin current density which can be used to switch a magnet efficiently and there is increasing interest in identifying materials with large spin Hall angle for lower switching current. Using experimentally benchmarked models, we show that composite structures can be designed using existing spin Hall materials such that the effective spin Hall angle is larger by an order of magnitude. The basic idea is to funnel spins from a large area of spin Hall material into a small area of ferromagnet using a normal metal with large spin diffusion length and low resistivity like Cu or Al. We show that this approach is increasingly effective as magnets get smaller. We avoid unwanted charge current shunting by the low resistive NM layer utilizing the newly discovered phenomenon of pure spin conduction in ferromagnetic insulators via magnon diffusion. We provide a spin circuit model for magnon diffusion in FMI that is benchmarked against recent experiments and theory.

Chiral effective-field theory of the nucleon spin structure

Science.gov (United States)

Pascalutsa, Vladimir

2017-01-01

I will review the recent chiral EFT calculations of the nucleon (spin) structure functions at low Q2, confronted with the Jefferson Lab measurements. The moments of the structure functions correspond with various polarizabilities, and I will explain why one of them - δLT - is especially interesting. I will also discuss how the spin structure functions at low Q enter in the atomic calculations of the hyperfine splittings and how they are impacting the ongoing experimental program at PSI (Switzerland) to measure the ground-state hyperfine splitting of muonic hydrogen. Partially supported by the Deutsche Forschungsgemeinschaft (DFG) through the Collaborative Research Center SFB 1044 [The Low-Energy Frontier of the Standard Model].

Quasiparticle semiconductor band structures including spin-orbit interactions.

Science.gov (United States)

Malone, Brad D; Cohen, Marvin L

2013-03-13

We present first-principles calculations of the quasiparticle band structure of the group IV materials Si and Ge and the group III-V compound semiconductors AlP, AlAs, AlSb, InP, InAs, InSb, GaP, GaAs and GaSb. Calculations are performed using the plane wave pseudopotential method and the 'one-shot' GW method, i.e. G(0)W(0). Quasiparticle band structures, augmented with the effects of spin-orbit, are obtained via a Wannier interpolation of the obtained quasiparticle energies and calculated spin-orbit matrix. Our calculations explicitly treat the shallow semicore states of In and Ga, which are known to be important in the description of the electronic properties, as valence states in the quasiparticle calculation. Our calculated quasiparticle energies, combining both the ab initio evaluation of the electron self-energy and the vector part of the pseudopotential representing the spin-orbit effects, are in generally very good agreement with experimental values. These calculations illustrate the predictive power of the methodology as applied to group IV and III-V semiconductors.

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

Energy Technology Data Exchange (ETDEWEB)

Vasilyev, D.; Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2016-08-15

We describe a new “complete” spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the “spin-polarizing mirror” type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å{sup −1}, at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution.

Proton radioactivity at non-collective prolate shape in high spin state of 94Ag

International Nuclear Information System (INIS)

Aggarwal, Mamta

2010-01-01

We predict proton radioactivity and structural transitions in high spin state of an excited exotic nucleus near proton drip line in a theoretical framework and investigate the nature and the consequences of the structural transitions on separation energy as a function of temperature and spin. It reveals that the rotation of the excited exotic nucleus 94 Ag at excitation energies around 6.7 MeV and angular momentum near 21h generates a rarely seen prolate non-collective shape and proton separation energy becomes negative which indicates proton radioactivity in agreement with the experimental results of Mukha et al. for 94 Ag.

Nuclear spin noise in the central spin model

Science.gov (United States)

Fröhling, Nina; Anders, Frithjof B.; Glazov, Mikhail

2018-05-01

We study theoretically the fluctuations of the nuclear spins in quantum dots employing the central spin model which accounts for the hyperfine interaction of the nuclei with the electron spin. These fluctuations are calculated both with an analytical approach using homogeneous hyperfine couplings (box model) and with a numerical simulation using a distribution of hyperfine coupling constants. The approaches are in good agreement. The box model serves as a benchmark with low computational cost that explains the basic features of the nuclear spin noise well. We also demonstrate that the nuclear spin noise spectra comprise a two-peak structure centered at the nuclear Zeeman frequency in high magnetic fields with the shape of the spectrum controlled by the distribution of the hyperfine constants. This allows for direct access to this distribution function through nuclear spin noise spectroscopy.

Interface-induced spin Hall magnetoresistance enhancement in Pt-based tri-layer structure.

Science.gov (United States)

Huang, Shun-Yu; Li, Hong-Lin; Chong, Cheong-Wei; Chang, Yu-Ying; Lee, Min-Kai; Huang, Jung-Chun-Andrew

2018-01-08

In this study, we integrated bilayer structure of covered Pt on nickel zinc ferrite (NZFO) and CoFe/Pt/NZFO tri-layer structure by pulsed laser deposition system for a spin Hall magnetoresistance (SMR) study. In the bilayer structure, the angular-dependent magnetoresistance (MR) results indicate that Pt/NZFO has a well-defined SMR behavior. Moreover, the spin Hall angle and the spin diffusion length, which were 0.0648 and 1.31 nm, respectively, can be fitted by changing the Pt thickness in the longitudinal SMR function. Particularly, the MR ratio of the bilayer structure (Pt/NZFO) has the highest changing ratio (about 0.135%), compared to the prototype structure Pt/Y 3 Fe 5 O 12 (YIG) because the NZFO has higher magnetization. Meanwhile, the tri-layer samples (CoFe/Pt/NZFO) indicate that the MR behavior is related with CoFe thickness as revealed in angular-dependent MR measurement. Additionally, comparison between the tri-layer structure with Pt/NZFO and CoFe/Pt bilayer systems suggests that the SMR ratio can be enhanced by more than 70%, indicating that additional spin current should be injected into Pt layer.

The study of very high spin states

International Nuclear Information System (INIS)

Nolan, P.J.

1992-01-01

Some examples are given of the study of very high spin states that decay by discrete line gamma-ray emission. States up to spin 70(h/2π) have been seen in superdeformed bands. In other bands with normal deformation the limit is near 50(h/2π). (Author)

Spin-frustrated V3 and Cu3 nanomagnets with Dzialoshinsky-Moriya exchange. 2. Spin structure, spin chirality and tunneling gaps

International Nuclear Information System (INIS)

Belinsky, Moisey I.

2009-01-01

The spin chirality and spin structure of the Cu 3 and V 3 nanomagnets with the Dzialoshinsky-Moriya (DM) exchange interaction are analyzed. The correlations between the vector κ and the scalar χ chirality are obtained. The DM interaction forms the spin chirality which is equal to zero in the Heisenberg clusters. The dependences of the spin chirality on magnetic field and deformations are calculated. The cluster distortions reduce the spin chirality. The vector chirality is reduced partially and the scalar chirality vanishes in the transverse magnetic field. In the isosceles clusters, the DM exchange and distortions determine the sign and degree of the spin chirality κ. The correlations between the chirality parameters κ n and the intensities of the EPR and INS transitions are obtained. The vector chirality κ n describes the spin chirality of the Cu 3 and V 3 nanomagnets, the scalar chirality describes the pseudoorbital moment of the DM cluster. It is shown that in the consideration of the DM exchange, the spin states DM mixing and tunneling gaps at level crossing fields depend on the coordinate system of the DM model. The calculations in the DM exchange models in the right-handed and left-handed frame show opposite magnetic behavior at the level crossing field and allow to explain the opposite schemes of the tunneling gaps and levels crossing, which have been obtained in different treatments. The results of the DM model in the right-handed frame are consistent with the results of the group-theoretical analysis, whereas the results in the left-handed frame are inconsistent with that. The correlations between the spin chirality of the ground state and tunneling gaps at the level crossing field are obtained for the equilateral and isosceles nanoclusters.

Spin-orbit coupling, electron transport and pairing instabilities in two-dimensional square structures

Energy Technology Data Exchange (ETDEWEB)

Kocharian, Armen N. [Department of Physics, California State University, Los Angeles, CA 90032 (United States); Fernando, Gayanath W.; Fang, Kun [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Palandage, Kalum [Department of Physics, Trinity College, Hartford, Connecticut 06106 (United States); Balatsky, Alexander V. [AlbaNova University Center Nordita, SE-106 91 Stockholm (Sweden)

2016-05-15

Rashba spin-orbit effects and electron correlations in the two-dimensional cylindrical lattices of square geometries are assessed using mesoscopic two-, three- and four-leg ladder structures. Here the electron transport properties are systematically calculated by including the spin-orbit coupling in tight binding and Hubbard models threaded by a magnetic flux. These results highlight important aspects of possible symmetry breaking mechanisms in square ladder geometries driven by the combined effect of a magnetic gauge field spin-orbit interaction and temperature. The observed persistent current, spin and charge polarizations in the presence of spin-orbit coupling are driven by separation of electron and hole charges and opposite spins in real-space. The modeled spin-flip processes on the pairing mechanism induced by the spin-orbit coupling in assembled nanostructures (as arrays of clusters) engineered in various two-dimensional multi-leg structures provide an ideal playground for understanding spatial charge and spin density inhomogeneities leading to electron pairing and spontaneous phase separation instabilities in unconventional superconductors. Such studies also fall under the scope of current challenging problems in superconductivity and magnetism, topological insulators and spin dependent transport associated with numerous interfaces and heterostructures.

Spin-orbit coupling, electron transport and pairing instabilities in two-dimensional square structures

Directory of Open Access Journals (Sweden)

Armen N. Kocharian

2016-05-01

Full Text Available Rashba spin-orbit effects and electron correlations in the two-dimensional cylindrical lattices of square geometries are assessed using mesoscopic two-, three- and four-leg ladder structures. Here the electron transport properties are systematically calculated by including the spin-orbit coupling in tight binding and Hubbard models threaded by a magnetic flux. These results highlight important aspects of possible symmetry breaking mechanisms in square ladder geometries driven by the combined effect of a magnetic gauge field spin-orbit interaction and temperature. The observed persistent current, spin and charge polarizations in the presence of spin-orbit coupling are driven by separation of electron and hole charges and opposite spins in real-space. The modeled spin-flip processes on the pairing mechanism induced by the spin-orbit coupling in assembled nanostructures (as arrays of clusters engineered in various two-dimensional multi-leg structures provide an ideal playground for understanding spatial charge and spin density inhomogeneities leading to electron pairing and spontaneous phase separation instabilities in unconventional superconductors. Such studies also fall under the scope of current challenging problems in superconductivity and magnetism, topological insulators and spin dependent transport associated with numerous interfaces and heterostructures.

Temperature dependence of the magnetization of canted spin structures

DEFF Research Database (Denmark)

Jacobsen, Henrik; Lefmann, Kim; Brok, Erik

2012-01-01

Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...... for the temperature dependence of the magnetization of a simple canted spin structure in which relaxation can take place at finite temperatures between spin configurations with different canting angles. We show that the saturation magnetization may either decrease or increase with decreasing temperature, depending...

Spin-orbit coupling effects in indium antimonide quantum well structures

Science.gov (United States)

Dedigama, Aruna Ruwan

Indium antimonide (InSb) is a narrow band gap material which has the smallest electron effective mass (0.014m0) and the largest electron Lande g-facture (-51) of all the III-V semiconductors. Spin-orbit effects of III-V semiconductor heterostructures arise from two different inversion asymmetries namely bulk inversion asymmetry (BIA) and structural inversion asymmetry (SIA). BIA is due to the zinc-blende nature of this material which leads to the Dresselhaus spin splitting consisting of both linear and cubic in-plane wave vector terms. As its name implies SIA arises due to the asymmetry of the quantum well structure, this leads to the Rashba spin splitting term which is linear in wave vector. Although InSb has theoretically predicted large Dresselhaus (760 eVA3) and Rashba (523 eA 2) coefficients there has been relatively little experimental investigation of spin-orbit coefficients. Spin-orbit coefficients can be extracted from the beating patterns of Shubnikov--de Haas oscillations (SdH), for material like InSb it is hard to use this method due to the existence of large electron Lande g-facture. Therefore it is essential to use a low field magnetotransport technique such as weak antilocalization to extract spin-orbit parameters for InSb. The main focus of this thesis is to experimentally determine the spin-orbit parameters for both symmetrically and asymmetrically doped InSb/InxAl 1-xSb heterostructures. During this study attempts have been made to tune the Rashba spin-orbit coupling coefficient by using a back gate to change the carrier density of the samples. Dominant phase breaking mechanisms for InSb/InxAl1-xSb heterostructures have been identified by analyzing the temperature dependence of the phase breaking field from weak antilocalization measurements. Finally the strong spin-orbit effects on InSb/InxAl1-xSb heterostructures have been demonstrated with ballistic spin focusing devices.

Rapid high-resolution spin- and angle-resolved photoemission spectroscopy with pulsed laser source and time-of-flight spectrometer

Science.gov (United States)

Gotlieb, K.; Hussain, Z.; Bostwick, A.; Lanzara, A.; Jozwiak, C.

2013-09-01

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-EF 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.

Fabrication of highly spin-polarized Co2FeAl0.5Si0.5 thin-films

Directory of Open Access Journals (Sweden)

M. Vahidi

2014-04-01

Full Text Available Ferromagnetic Heusler Co2FeAl0.5Si0.5 epitaxial thin-films have been fabricated in the L21 structure with saturation magnetizations over 1200 emu/cm3. Andreev reflection measurements show that the spin polarization is as high as 80% in samples sputtered on unheated MgO (100 substrates and annealed at high temperatures. However, the spin polarization is considerably smaller in samples deposited on heated substrates.

Detailed high-spin spectroscopy and the search for the wobbling mode in 171Ta

International Nuclear Information System (INIS)

Hartley, D J.; Mohr, W.H.; Vanhoy, J.R.

2005-01-01

High-spin states in 171 Ta were populated in the 124 Sn( 51 V,4n) reaction at 228 MeV to search for evidence of stable triaxial deformation. Identification of a wobbling sequence based on the previously known πi 13/2 structure would provide a unique signature for this rarely observed shape. No such sequence was identified in these data, which suggests that the island of triaxial strongly deformed bands may be smaller than once thought. However, over 200 new transitions and two new bands were placed in the level scheme and the sequence based on the πi 13/2 orbital could be observed up to spin and parity I π =(101/2 + ). The relative excitations of all the sequences were determined and the ground state of 171 Ta was found to have 5/2 + quantum numbers, contrary to previous reports. All of the previously known structures were extended to much higher spin and their high-frequency band crossings are interpreted within the framework of the cranked shell model

Spin structure of the neutron ({sup 3}He) and the Bjoerken sum rule

Energy Technology Data Exchange (ETDEWEB)

Meziani, Z.E. [Stanford Univ., CA (United States)

1994-12-01

A first measurement of the longitudinal asymmetry of deep-inelastic scattering of polarized electrons from a polarized {sup 3}He target at energies ranging from 19 to 26 GeV has been performed at the Stanford Linear Accelerator Center (SLAC). The spin-structure function of the neutron g{sub 1}{sup n} has been extracted from the measured asymmetries. The Quark Parton Model (QPM) interpretation of the nucleon spin-structure function is examined in light of the new results. A test of the Ellis-Jaffe sum rule (E-J) on the neutron is performed at high momentum transfer and found to be satisfied. Furthermore, combining the proton results of the European Muon Collaboration (EMC) and the neutron results of E-142, the Bjoerken sum rule test is carried at high Q{sup 2} where higher order Perturbative Quantum Chromodynamics (PQCD) corrections and higher-twist corrections are smaller. The sum rule is saturated to within one standard deviation.

Non magnetic neutron spin quantum precession using multilayer spin splitter and a phase-spin echo interferometer

Energy Technology Data Exchange (ETDEWEB)

Ebisawa, T.; Tasaki, S.; Kawai, T.; Akiyoshi, T. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Achiwa, N.; Hino, M.; Otake, Y.; Funahashi, H.

1996-08-01

The authors have developed cold neutron optics and interferometry using multilayer mirrors. The advantages of the multilayer mirrors are their applicability to long wavelength neutrons and a great variety of the mirror performance. The idea of the present spin interferometry is based on nonmagnetic neutron spin quantum precession using multilayer spin splitters. The equation for polarized neutrons means that the polarized neutrons are equivalent to the coherent superposition of two parallel spin eigenstates. The structure and principle of a multilayer spin splitter are explained, and the nonmagnetic gap layer of the multilayer spin splitter gives rise to neutron spin quantum precession. The performance test of the multilayer spin splitter were made with a new spin interferometer, which is analogous optically to a spin echo system with vertical precession field. The spin interferometers were installed at Kyoto University research reactor and the JRR-3. The testing method and the results are reported. The performance tests on a new phase-spin echo interferometer are described, and its applications to the development of a high resolution spin echo system and a Jamin type cold neutron interferometer are proposed. (K.I.)

Local quark-hadron duality of nucleon spin structure functions with target mass corrections

International Nuclear Information System (INIS)

Dong, Y.B. . E-mail dongyb@mail.ihep.ac.cn; Chen, D.Y.

2007-01-01

Target mass corrections to nucleon spin structure functions are analyzed. Our results show that the corrections are important to the structure functions in a large x region. Moreover, they play a remarkable role to the local quark-hadron duality of the nucleon spin structure functions in three individual inelastic resonance production regions

The Spin Structure of the Proton in the Resonance Region

Energy Technology Data Exchange (ETDEWEB)

Fatemi, Renee H. [Univ. of Virginia, Charlottesville, VA (United States)

2002-01-01

Inclusive double spin asymmetries have been measured for $\\vec{p}$($\\vec{e}$,e') using the CLAS detector and a polarized ¹⁵NH₃ target at Jefferson Lab in 1998. The virtual photon asymmetry A₁, the longitudinal spin structure function, g₁ (x, Q²), and the first moment Γ$1\\atop{p}$, have been extracted for a Q² range of 0.15-2.0 GeV². These results provide insight into the low Q² evolution of spin dependent asymmetries and structure functions as well as the transition of Γ$1\\atop{p}$ from the photon point, where the Gerasimov, Drell and Hearn Sum Rule is expected to be satisfied, to the deep inelastic region.

New materials research for high spin polarized current

International Nuclear Information System (INIS)

Tezuka, Nobuki

2012-01-01

The author reports here a thorough investigation of structural and magnetic properties of Co 2 FeAl 0.5 Si 0.5 Heusler alloy films, and the tunnel magnetoresistance effect for junctions with Co 2 FeAl 0.5 Si 0.5 electrodes, spin injection into GaAs semiconductor from Co 2 FeAl 0.5 Si 0.5 , and spin filtering phenomena for junctions with CoFe 2 O 4 ferrite barrier. It was observed that tunnel magnetoresistance ratio up to 832%(386%) at 9 K (room temperature), which corresponds to the tunnel spin polarization of 0.90 (0.81) for the junctions using Co 2 FeAl 0.5 Si 0.5 Heusler electrodes by optimizing the fabrication condition. It was also found that the tunnel magnetoresistance ratio are almost the same between the junctions with Co 2 FeAl 0.5 Si 0.5 Heusler electrodes on Cr buffered (1 0 0) and (1 1 0) MgO substrates, which indicates that tunnel spin polarization of Co 2 FeAl 0.5 Si 0.5 for these two direction are almost the same. The next part of this paper is a spin filtering effect using a Co ferrite. The spin filtering effect was observed through a thin Co-ferrite barrier. The inverse type tunnel magnetoresistance ratio of −124% measured at 10 K was obtained. The inverse type magnetoresistance suggests the negative spin polarization of Co-ferrite barrier. The magnetoresistance ratio of −124% corresponds to the spin polarization of −0.77 by the Co-ferrite barrier. The last part is devoted to the spin injection from Co 2 FeAl 0.5 Si 0.5 into GaAs. The spin injection signal was clearly obtained by three terminal Hanle measurement. The spin relaxation time was estimated to be 380 ps measured at 5 K.

The spin structure of the pion

Energy Technology Data Exchange (ETDEWEB)

Broemmel, D. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)]|[Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Diehl, M. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

2007-08-15

We present the first calculation of the transverse spin structure of the pion in lattice QCD. We find a characteristic asymmetry in the spatial distribution of transversely polarized quarks. This asymmetry is very similar in magnitude to the analogous asymmetry we previously obtained for quarks in the nucleon. Our results support the hypothesis that all Boer-Mulders functions are alike. (orig.)

Circular dichroism and site-directed spin labeling reveal structural and dynamical features of high-pressure states of myoglobin

Science.gov (United States)

Lerch, Michael T.; Horwitz, Joseph; McCoy, John; Hubbell, Wayne L.

2013-01-01

Excited states of proteins may play important roles in function, yet are difficult to study spectroscopically because of their sparse population. High hydrostatic pressure increases the equilibrium population of excited states, enabling their characterization [Akasaka K (2003) Biochemistry 42:10875–85]. High-pressure site-directed spin-labeling EPR (SDSL-EPR) was developed recently to map the site-specific structure and dynamics of excited states populated by pressure. To monitor global secondary structure content by circular dichroism (CD) at high pressure, a modified optical cell using a custom MgF2 window with a reduced aperture is introduced. Here, a combination of SDSL-EPR and CD is used to map reversible structural transitions in holomyoglobin and apomyoglobin (apoMb) as a function of applied pressure up to 2 kbar. CD shows that the high-pressure excited state of apoMb at pH 6 has helical content identical to that of native apoMb, but reversible changes reflecting the appearance of a conformational ensemble are observed by SDSL-EPR, suggesting a helical topology that fluctuates slowly on the EPR time scale. Although the high-pressure state of apoMb at pH 6 has been referred to as a molten globule, the data presented here reveal significant differences from the well-characterized pH 4.1 molten globule of apoMb. Pressure-populated states of both holomyoglobin and apoMb at pH 4.1 have significantly less helical structure, and for the latter, that may correspond to a transient folding intermediate. PMID:24248390

High-spin states in 66Zn

International Nuclear Information System (INIS)

Bruandet, J.F.; Agard, M.; Giorni, A.; Longequeue, J.P.; Morand, C.; Tsan Ung Chan.

1975-01-01

The structure of 66 Zn has been investigated by studying the yield functions, angular distributions and coincidence relationships of the γ-rays emitted during bombardment of an enriched 64 Ni foil by α particles of medium energy 27MeV. Spins up to 10 h were assigned to observed states [fr

Feeding times of high spin states in sup(152,154)Dy: Probes of nuclear structure above the yrast line

International Nuclear Information System (INIS)

Azgui, F.; Emling, H.; Grosse, E.; Michel, C.; Simon, R.S.; Spreng, W.; Wollersheim, H.J.; Khoo, T.L.; Chowdhury, P.; Frekers, D.; Janssens, R.V.F.; Pakkanen, A.; Daly, P.J.; Kortelahti, M.; Schwalm, D.; Seiler-Clark, G.

1985-01-01

Measurements of feeding times of high spin yrast states up to spin 30 (h/2π) in 154 Dy and 36 (h/2π) in 152 Dy were utilized to obtain information about possible spin dependent shape changes. The reactions 25 Mg ( 134 Xe, 5n), 124 Sn ( 34 S, 4n) and 25 Mg ( 132 Xe, 5n), 122 Sn ( 34 S, 4n) were used to populate the high spin states in 154 Dy and 152 Dy, respectively. Feeding times as well as lifetimes were determined with the recoil distance technique. In 152 Dy only long feeding times (>=10 ps) could be identified, indicating that the aligned-particle yrast states are fed through configurations of similar character, with little direct population from collective cascades in the continuum region. In 154 Dy discrete states with I<=30 (h/2π) have lifetimes which are characteristically collective, whereas the preyrast cascades exhibit both fast (< or approx.1 ps) and slow (proportional10 ps) feeding components. The latter imply a change with increasing spin from collective to aligned-particle character, probably associated with a prolate to oblate shape transition. (orig.)

High spin rotational bands in Zn

Indian Academy of Sciences (India)

We present here some preliminary results from our studies in the. ~ ¼ region in which we have observed an yrast band structure in Zn extending to spin (41/2 ). ... gaps implies that nuclei may exhibit different shapes at different excitation energies. .... uration, identifying previously unobserved states up to an excitation energy ...

High-spin excitations of atomic nuclei

International Nuclear Information System (INIS)

Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing

2004-01-01

The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)

A New Spin on Photoemission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Jozwiak, Chris [Univ. of California, Berkeley, CA (United States)

2008-12-01

The electronic spin degree of freedom is of general fundamental importance to all matter. Understanding its complex roles and behavior in the solid state, particularly in highly correlated and magnetic materials, has grown increasingly desirable as technology demands advanced devices and materials based on ever stricter comprehension and control of the electron spin. However, direct and efficient spin dependent probes of electronic structure are currently lacking. Angle Resolved Photoemission Spectroscopy (ARPES) has become one of the most successful experimental tools for elucidating solid state electronic structures, bolstered by-continual breakthroughs in efficient instrumentation. In contrast, spin-resolved photoemission spectroscopy has lagged behind due to a lack of similar instrumental advances. The power of photoemission spectroscopy and the pertinence of electronic spin in the current research climate combine to make breakthroughs in Spin and Angle Resolved Photoemission Spectroscopy (SARPES) a high priority . This thesis details the development of a unique instrument for efficient SARPES and represents a radical departure from conventional methods. A custom designed spin polarimeter based on low energy exchange scattering is developed, with projected efficiency gains of two orders of magnitude over current state-of-the-art polarimeters. For energy analysis, the popular hemispherical analyzer is eschewed for a custom Time-of-Flight (TOF) analyzer offering an additional order of magnitude gain in efficiency. The combined instrument signifies the breakthrough needed to perform the high resolution SARPES experiments necessary for untangling the complex spin-dependent electronic structures central to today's condensed matter physics.

The Spin Structure of the Proton at Low Q2: A Measurement of the Structure Function g2p

Energy Technology Data Exchange (ETDEWEB)

Gu, Chao [Univ. of Virginia, Charlottesville, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-08-31

The spin structure of the nucleon has remained as one of the key points of interest in hadronic physics, which has attracted many efforts from both experimentalists and theorists. Quantum Chromodynamics (QCD) is the fundamental theory that describes the strong interaction. It has been verified in the asymptotically free region. However, the non-perturbative confinement of quarks within the nucleon is still not well understood within QCD. In the non-perturbative regime, low-energy effective field theories such as chiral perturbation theory (XPT) provide predictions for the spin structure functions. The neutron spin structure functions, gp1 and gp2 , and the proton spin structure function, gp1, have been measured over a wide kinematic range and compared with the theoretical predictions. However, the proton spin structure function, gp2, remains largely unmeasured. The E08-027 collaboration successfully performed the first measurement of the inclusive electron-proton scattering in the kinematic range 0.02 < Q2 < 0.2 GeV2. The experiment took place in experimental Hall A at Jefferson Lab in 2012. A longitudinally polarized electron beam with incident energies between 1.1 GeV and 3.3 GeV was scattered from a longitudinally or transversely polarized NH3 target. Asymmetries and polarized cross-section differences were measured in the resonance region to extract the proton spin structure functions g2. The results allow us to obtain the generalized spin polarizabilities γ0 and δLT and test the Burkhardtt-Cottingham (BC) sum rule. Chiral perturbation theory is expected to work in this kinematic range and this measurement of δLT will give a benchmark test to XPT calculations. This thesis will discuss preliminary results from the E08-027 data analysis.

Spin-polaron theory of high-Tc superconductivity: I, spin polarons and high-Tc pairing

International Nuclear Information System (INIS)

Wood, R.F.

1993-06-01

The concept of a spin polaron is introduced and contrasted with the more familiar ionic polaron picture. A brief review of aspects of ionic bipolaronic superconductivity is given with particular emphasis on the real-space pairing and true Bose condensation characteristics. The formation energy of spin polarons is then calculated in analogy with ionic polarons. The spin-flip energy of a Cu spin in an antiferromagnetically aligned CuO 2 plane is discussed. It is shown that the introduction of holes into the CuO 2 planes will always lead to the destruction of long-range AF ordering due to the formation of spin polarons. The pairing of two spin polarons can be expected because of the reestablishment of local (short-range) AF ordering; the magnitude of the pairing energy is estimated using a simplified model. The paper closes with a brief discussion of the formal theory of spin polarons

Unresolved gamma rays from high-spin states

International Nuclear Information System (INIS)

Stephens, F.S.

1985-08-01

The γ-rays which are emitted from the highest spin states in nuclei cannot be resolved using present techniques. Nevertheless, methods are being developed to study nuclear structures in this spin range. For example, coincidence data has been used in the study of superdeformations and moments of inertia. While the general properties of these correlation plots are in accord with present expectations, there are several puzzling features of the data which require more study. One unresolved aspect concerns γ-ray energy spreads in a given decay pathway. In addition, higher-order correlation methods are in various stages of inception. 15 refs., 16 figs

The spin dependent structure function g1 of the deuteron and the proton

International Nuclear Information System (INIS)

Klostermann, L.

1995-01-01

This thesis presents a study on the spin structure of the nucleon, via deep inelastic scattering (DIS) of polarised nuons on polarised proton and deuterium targets. The work was done in the Spin Muon Collaboration (SMC) at CERN in Geneva. From the asymmetry in the scattering cross section for nucleon and lepton spins parallel and anti-parallel, one con determine the spin dependent structure function g 1 , which contains information on the quark and gluon spin distribution functions. The interpretation in the frame work of the quark parton model (QPM) of earlier results on g 1 p by the European Muon Collaboration (EMC), gave an indication that only a small fraction of the proton spin, compatible with zero, is carried by the spins of the constituent quarks. The SMC was set up to check this unexpected result with improved accuracy, and to combine measurements of g 1 p and g 1 d to test a fundamental sum rule in quantum chromodynamics (QCD), the Bjorken sum rule. (orig./WL)

M-theory on eight-manifolds revisited: N = 1 supersymmetry and generalized Spin(7) structures

International Nuclear Information System (INIS)

Tsimpis, Dimitrios

2006-01-01

The requirement of N = 1 supersymmetry for M-theory backgrounds of the form of a warped product M x w X, where X is an eight-manifold and M is three-dimensional Minkowski or AdS space, implies the existence of a nowhere-vanishing Majorana spinor ξ on X. ξ lifts to a nowhere-vanishing spinor on the auxiliary nine-manifold Y: = X x S 1 , where S 1 is a circle of constant radius, implying the reduction of the structure group of Y to Spin(7). In general, however, there is no reduction of the structure group of X itself. This situation can be described in the language of generalized Spin(7) structures, defined in terms of certain spinors of Spin(TY+T*Y). We express the condition for N = 1 supersymmetry in terms of differential equations for these spinors. In an equivalent formulation, working locally in the vicinity of any point in X in terms of a 'preferred' Spin(7) structure, we show that the requirement of N = 1 supersymmetry amounts to solving for the intrinsic torsion and all irreducible flux components, except for the one lying in the 27 of Spin(7), in terms of the warp factor and a one-form L on X (not necessarily nowhere-vanishing) constructed as a ξ bilinear; in addition, L is constrained to satisfy a pair of differential equations. The formalism based on the group Spin(7) is the most suitable language in which to describe supersymmetric compactifications on eight-manifolds of Spin(7) structure, and/or small-flux perturbations around supersymmetric compactifications on manifolds of Spin(7) holonomy

Spin current and spin transfer torque in ferromagnet/superconductor spin valves

Science.gov (United States)

Moen, Evan; Valls, Oriol T.

2018-05-01

Using fully self-consistent methods, we study spin transport in fabricable spin valve systems consisting of two magnetic layers, a superconducting layer, and a spacer normal layer between the ferromagnets. Our methods ensure that the proper relations between spin current gradients and spin transfer torques are satisfied. We present results as a function of geometrical parameters, interfacial barrier values, misalignment angle between the ferromagnets, and bias voltage. Our main results are for the spin current and spin accumulation as functions of position within the spin valve structure. We see precession of the spin current about the exchange fields within the ferromagnets, and penetration of the spin current into the superconductor for biases greater than the critical bias, defined in the text. The spin accumulation exhibits oscillating behavior in the normal metal, with a strong dependence on the physical parameters both as to the structure and formation of the peaks. We also study the bias dependence of the spatially averaged spin transfer torque and spin accumulation. We examine the critical-bias effect of these quantities, and their dependence on the physical parameters. Our results are predictive of the outcome of future experiments, as they take into account imperfect interfaces and a realistic geometry.

High-spin states in 82Sr

International Nuclear Information System (INIS)

Baktash, C.; Halper, M.L.; Garcia Bermudez, G.J.

1989-01-01

As recent theoretical calculations that predicted the onset of superdeformation in the A ≅ 80 region, the 52 Cr( 34 S,2p2n) reaction at 130 MeV beam energy was employed to populate the high-spin states in 82 Sr. The detection system consisted of the ORNL Compton-Suppression Spectrometer System (18 Ge detectors), the Spin Spectrometer, and the 4 φ CsI Dwarf Ball of Washington University. Off-line analysis of the proton-gated data resulted in nearly 170 million Ge-Ge pairs, which were mostly due to the 2p2n channel. A decay scheme extending to spin I=27h has been established. No strong evidence for the presence of superdeformed states in 82 Sr was found in a preliminary analysis of the data. (Author) [es

On the structure and spin states of Fe(III)-EDDHA complexes.

Science.gov (United States)

Gómez-Gallego, Mar; Fernández, Israel; Pellico, Daniel; Gutiérrez, Angel; Sierra, Miguel A; Lucena, Juan J

2006-07-10

DFT methods are suitable for predicting both the geometries and spin states of EDDHA-Fe(III) complexes. Thus, extensive DFT computational studies have shown that the racemic-Fe(III) EDDHA complex is more stable than the meso isomer, regardless of the spin state of the central iron atom. A comparison of the energy values obtained for the complexes under study has also shown that high-spin (S = 5/2) complexes are more stable than low-spin (S = 1/2) ones. These computational results matched the experimental results of the magnetic susceptibility values of both isomers. In both cases, their behavior has been fitted as being due to isolated high-spin Fe(III) in a distorted octahedral environment. The study of the correlation diagram also confirms the high-spin iron in complex 2b. The geometry optimization of these complexes performed with the standard 3-21G* basis set for hydrogen, carbon, oxygen, and nitrogen and the Hay-Wadt small-core effective core potential (ECP) including a double-xi valence basis set for iron, followed by single-point energy refinement with the 6-31G* basis set, is suitable for predicting both the geometries and the spin-states of EDDHA-Fe(III) complexes. The presence of a high-spin iron in Fe(III)-EDDHA complexes could be the key to understanding their lack of reactivity in electron-transfer processes, either chemically or electrochemically induced, and their resistance to photodegradation.

Experimental verification of the rotational type of chiral spin spiral structures by spin-polarized scanning tunneling microscopy.

Science.gov (United States)

Haze, Masahiro; Yoshida, Yasuo; Hasegawa, Yukio

2017-10-16

We report on experimental verification of the rotational type of chiral spin spirals in Mn thin films on a W(110) substrate using spin-polarized scanning tunneling microscopy (SP-STM) with a double-axis superconducting vector magnet. From SP-STM images using Fe-coated W tips magnetized to the out-of-plane and [001] directions, we found that both Mn mono- and double-layers exhibit cycloidal rotation whose spins rotate in the planes normal to the propagating directions. Our results agree with the theoretical prediction based on the symmetry of the system, supporting that the magnetic structures are driven by the interfacial Dzyaloshinskii-Moriya interaction.

Spin asymmetry Ad1 and the spin-dependent structure function gd1 of the deuteron at low values of x and Q2

Czech Academy of Sciences Publication Activity Database

Alexakhin, V.; Alexandrov, Y.; Alexeev, G.; Amoroso, A.; Badelek, B.; Balestra, F.; Ball, J.; Baum, G.; Bedfer, Y.; Berglund, P.; Bernet, C.; Bertini, R.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Bravar, A.; Bressan, A.; Burtin, E.; Bussa, M.; Bytchkov, V.; Cerini, L.; Chapiro, A.; Cicuttin, A.; Colantoni, M.; Colavita, A.; Costa, S.; Crespo, M.; d'Hose, N.; Dalla Torre, S.; Dasgupta, S. S.; De Masi, R.; Dedek, N.; Denisov, O.; Dhara, L.; Diaz Kavka, V.; Dinkelbach, A.; Dolgopolov, A.; Donskov, S.; Dorofeev, V.; Doshita, N.; Duic, V.; Dünnweber, W.; Ehlers, J.; Eversheim, P.; Eyrich, W.; Fabro, M.; Faessler, M.; Falaleev, V.; Fauland, P.; Ferrero, A.; Ferrero, L.; Finger, M.; Finger jr., M.; Fischer, H.; Franz, J.; Friedrich, J.; Frolov, V.; Fuchs, U.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gobbo, B.; Goertz, S.; Gorin, A.; Grajek, O.; Grasso, A.; Grube, B.; Grünemaier, A.; Hannappel, J.; von Harrach, D.; Hasegawa, T.; Hedicke, S.; Heinsius, F.; Hermann, R.; Hess, C.; Hinterberger, F.; von Hodenberg, M.; Horikawa, N.; Horikawa, S.; Ijaduola, R.; Ilgner, C.; Ioukaev, A.; Ishimoto, S.; Ivanov, O.; Iwata, T.; Jahn, R.; Janata, A.; Joosten, R.; Jouravlev, N. I.; Kabuss, E.; Kalinnikov, V.; Kang, D.; Karstens, F.; Kastaun, W.; Ketzer, B.; Khaustov, G.; Khokhlov, Y.; Khomutov, N.; Kisselev, Y.; Klein, F.; Koblitz, S.; Koivuniemi, J.; Kolosov, V.; Komissarov, E.; Kondo, K.; Königsmann, K.; Konoplyannikov, A.; Konorov, I.; Konstantinov, V.; Korentchenko, A.; Korzenev, A.; Kotzinian, A.; Koutchinski, N.; Kowalik, K.; Kravchuk, N.; Krivokhizhin, G.; Kroumchtein, Z.; Kuhn, R.; Kunne, F.; Kurek, K.; Ladygin, M.; Lamanna, M.; Le Goff, J.; Leberig, M.; Lichtenstadt, J.; Liska, T.; Ludwig, I.; Maggiora, A.; Maggiora, M.; Magnon, A.; Mallot, G.; Manuilov, I.; Marchand, C.; Marroncle, J.; Martin, A.; Marzec, J.; Matsuda, T.; Maximov, A.; Medved, K.; Meyer, W.; Mielech, A.; Mikhailov, Y.; Moinester, M.; Nähle, O.; Nassalski, J.; Neliba, S.; Neyret, D.; Nikolaenko, V.; Nozdrin, A.; Obraztsov, V.; Olshevsky, A.; Ostrick, M.; Padee, A.; Pagano, P.; Panebianco, S.; Panzieri, D.; Paul, S.; Pereira, H.; Peshekhonov, D.; Peshekhonov, V.; Piragino, G.; Platchkov, S.; Platzer, K.; Pochodzalla, J.; Polyakov, V.; Popov, A.; Pretz, J.; Quintans, C.; Ramos, S.; Rebourgeard, P.; Reicherz, G.; Reymann, J.; Rith, K.; Rozhdestvensky, A.; Rondio, E.; Sadovski, A.; Saller, E.; Samoylenko, V.; Sandacz, A.; Sans, M.; Sapozhnikov, M.; Savin, I.; Schiavon, P.; Schill, C.; Schmidt, T.; Schmitt, H.; Schmitt, L.; Shevchenko, O.; Shishkin, A.; Siebert, H.; Sinha, L.; Sissakian, A.; Skachkova, A.; Slunecka, M.; Smirnov, G.; Sozzi, F.; Sugonyaev, V.; Srnka, Aleš; Stinzing, F.; Stolarski, M.; Sulc, M.; Sulej, R.; Takabayashi, N.; Tchalishev, V.; Tassarotto, F.; Teufel, A.; Thers, D.; Tkatchev, L.; Toeda, T.; Tretyak, V.; Trousov, S.; Varanda, M.; Virius, M.; Vlassov, N.; Wagner, M.; Webb, R.; Weise, E.; Weitzel, Q.; Wiedner, U.; Wiesmann, M.; Windmolders, R.; Wirth, S.; Wislicki, W.; Zanetti, A.; Zaremba, K.; Zhao, J.; Ziegler, R.; Zvyagin, A.

2007-01-01

Roč. 647, 5-6 (2007), s. 330-340 ISSN 0370-2693 R&D Projects: GA MŠk(CZ) ME 492 Institutional research plan: CEZ:AV0Z20650511 Keywords : inelastic muon scattering * spin * structure function Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 4.189, year: 2007

Widespread spin polarization effects in photoemission from topological insulators

Energy Technology Data Exchange (ETDEWEB)

Jozwiak, C.; Chen, Y. L.; Fedorov, A. V.; Analytis, J. G.; Rotundu, C. R.; Schmid, A. K.; Denlinger, J. D.; Chuang, Y.-D.; Lee, D.-H.; Fisher, I. R.; Birgeneau, R. J.; Shen, Z.-X.; Hussain, Z.; Lanzara, A.

2011-06-22

High-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES) was performed on the three-dimensional topological insulator Bi{sub 2}Se{sub 3} using a recently developed high-efficiency spectrometer. The topological surface state's helical spin structure is observed, in agreement with theoretical prediction. Spin textures of both chiralities, at energies above and below the Dirac point, are observed, and the spin structure is found to persist at room temperature. The measurements reveal additional unexpected spin polarization effects, which also originate from the spin-orbit interaction, but are well differentiated from topological physics by contrasting momentum and photon energy and polarization dependencies. These observations demonstrate significant deviations of photoelectron and quasiparticle spin polarizations. Our findings illustrate the inherent complexity of spin-resolved ARPES and demonstrate key considerations for interpreting experimental results.

Self-similar spectral structures and edge-locking hierarchy in open-boundary spin chains

International Nuclear Information System (INIS)

Haque, Masudul

2010-01-01

For an anisotropic Heisenberg (XXZ) spin chain, we show that an open boundary induces a series of approximately self-similar features at different energy scales, high up in the eigenvalue spectrum. We present a nonequilibrium phenomenon related to this fractal structure, involving states in which a connected block near the edge is polarized oppositely to the rest of the chain. We show that such oppositely polarized blocks can be 'locked' to the edge of the spin chain and that there is a hierarchy of edge-locking effects at various orders of the anisotropy. The phenomenon enables dramatic control of quantum-state transmission and magnetization control.

Helicity in proton–proton elastic scattering and the spin structure of the pomeron

Directory of Open Access Journals (Sweden)

Carlo Ewerz

2016-12-01

Full Text Available We discuss different models for the spin structure of the nonperturbative pomeron: scalar, vector, and rank-2 symmetric tensor. The ratio of single-helicity-flip to helicity-conserving amplitudes in polarised high-energy proton–proton elastic scattering, known as the complex r5 parameter, is calculated for these models. We compare our results to experimental data from the STAR experiment. We show that the spin-0 (scalar pomeron model is clearly excluded by the data, while the vector pomeron is inconsistent with the rules of quantum field theory. The tensor pomeron is found to be perfectly consistent with the STAR data.

Spin Choreography: Basic Steps in High Resolution NMR (by Ray Freeman)

Science.gov (United States)

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.

The Spin Structure of the Neutron

Energy Technology Data Exchange (ETDEWEB)

Churchwell, S

2003-12-18

A description of SLAC experiment E154, a precision measurement of the neutron's longitudinal spin structure function g{sub 1}{sup n}, is presented. Deep inelastic electron scattering was used to measure the structure function in the kinematic range 0.014 < x < 0.7, and 1 < Q{sup 2} < 17 GeV{sup 2}. A measurement of the transverse spin structure function g{sub 2}{sup n} was also made, but with significantly lower statistical precision. Electrons with an average polarization of 82 {+-} 2% and an energy of 48.3 GeV were scattered off polarized {sup 3}He nuclei having an average polarization of 38%. Two independent magnetic spectrometers set at scattering angles of 2.75{sup o} and 5.5{sup o} were used to acquire about 100 million events during a two month run in late 1995. The data were analyzed to yield the integral over the measured region: {integral}{sub 0.014}{sup 0.7} g{sub 1}{sup n}(x)dx = -0.036 {+-} 0.004(stat) {+-} 0.005(syst), which is several standard deviations below the Ellis-Jaffe sum rule predictions. When these data were combined with the proton g{sub 1}{sup p} structure function data from the SMC and E143 experiments, the Bjorken sum rule over the measured x range was found to be within 10% of the predicted value. The integral of the g{sub 2}{sup n} data, dominated by the statistical uncertainty, was found to be {integral}{sub 0.014}{sup 0.7} g{sub 2}{sup n}(x)dx = 0.19 {+-} 0.17(stat) {+-} 0.02(syst), in agreement with the Burkhardt-Cottingham sum rule prediction. The g{sub 1}{sup n} structure function data at low x were found to be inconsistent with the traditional asymptotic forms, bringing into question the methods used in the past.

Electrical spin injection into high mobility 2D systems.

Science.gov (United States)

Oltscher, M; Ciorga, M; Utz, M; Schuh, D; Bougeard, D; Weiss, D

2014-12-05

We report on spin injection into a high mobility 2D electron system confined at an (Al,Ga)As/GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results.

Structural features of spin-coated thin films of binary AsxS100−x chalcogenide glass system

International Nuclear Information System (INIS)

Cook, J.; Slang, S.; Golovchak, R.; Jain, H.; Vlcek, M.; Kovalskiy, A.

2015-01-01

Spin-coating technology offers a convenient method for fabricating photostable chalcogenide glass thin films that are especially attractive for applications in IR optics. In this paper we report the structure of spin-coated As x S 100−x (x = 30, 35, 40) thin films as determined using high resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, especially in relation to composition (i.e. As/S ratio) and preparation process variables. It was observed that As atoms during preparation have a tendency to precipitate out in close to stoichiometric compositions. The mechanism of bonding between the inorganic matrix and organic residuals is discussed based on the experimental data. A weak interaction between S ions and amine-based clusters is proposed as the basis of structural organization of the organic–inorganic interface. - Highlights: • As–S spin-coated chalcogenide thin films with different As/S were fabricated. • XPS measurements support the cluster-like structure of spin-coated films. • As 2 O 3 was confirmed as the composition of precipitate formed during dissolution. • Lack of As–As bonds explains the observed photostability of the thin films

The deuteron spin-dependent structure function and its first moment

Czech Academy of Sciences Publication Activity Database

Alexakhin, V. Yu.; Alexandrov, Yu.; Alexeev, G. D.; Alexeev, M.; Amoroso, A.; Badelek, B.; Balestra, F.; Ball, J.; Barth, J.; Baum, G.; Becker, M.; Bedfer, Y.; Bernet, C.; Bertini, R.; Bettinelli, M.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Bressan, A.; Brona, G.; Burtin, E.; Bussa, M.P.; Bytchkov, V.N.; Chapiro, A.; Cicuttin, A.; Colantoni, M.; Colavita, A.A.; Costa, S.; Crespo, M.L.; d'Hose, N.; Dalla Torre, S.; Das, S.; Dasgupta, S. S.; De Masi, R.; Dedek, N.; Demchenko, D.; Denisov, O.Yu.; Dhara, L.; Diaz, V.; Dinkelbach, A. M.; Donskov, S.V.; Dorofeev, V. A.; Doshita, N.; Duic, V.; Dunnweber, W.; Efremov, A.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Fauland, P.; Ferrero, A.; Ferrero, L.; Finger, M.; Finger jr., M.; Fischer, H.; Franz, J.; Friedrich, J.M.; Frolov, V.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gobbo, B.; Goertz, S.; Gorin, A.M.; Grajek, O.A.; Grasso, A.; Grube, B.; Guskov, A.; Haas, F.; Hannappel, J.; von Harrach, D.; Hasegawa, T.; Hedicke, S.; Heinsius, F.H.; Hermann, R.; Hess, C.; Hinterberger, F.; von Hodenberg, M.; Horikawa, N.; Horikawa, S.; Horn, I.; Ilgner, C.; Ioukaev, A.I.; Ivanchin, I.; Ivanov, O.; Iwata, T.; Jahn, R.; Janata, A.; Joosten, R.; Jouravlev, N. I.; Kabuss, E.; Kang, D.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu.A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koblitz, S.; Koivuniemi, J.H.; Kolosov, V.N.; Komissarov, E.V.; Kondo, K.; Konigsmann, K.; Konorov, I.; Konstantinov, V.F.; Korentchenko, A.S.; Korzenev, A.; Kotzinian, A.M.; Koutchinski, N.A.; Kouznetsov, O.; Kowalik, K.; Kramer, D.; Kravchuk, N.P.; Krivokhizhin, G.V.; Kroumchtein, Z.V.; Kubart, J.; Kuhn, R.; Kukhtin, V.; Kunne, F.; Kurek, K.; Ladygin, M.E.; Lamanna, M.; Le Goff, J.M.; Leberig, M.; Lednev, A.A.; Lehmann, A.; Lichtenstadt, J.; Liska, T.; Ludwig, I.; Maggiora, A.; Maggiora, M.; Magnon, A.; Mallot, G.K.; Marchand, C.; Marroncle, J.; Martin, A.; Marzec, J.; Masek, L.; Massmann, F.; Matsuda, T.; Matthia, D.; Maximov, A.N.; Meyer, W.; Mielech, A.; Mikhailov, Yu.V.; Moinester, M.A.; Nagel, T.; Nahle, O.; Nassalski, J.; Neliba, S.; Neyret, D.P.; Nikolaenko, V.I.; Nikolaev, K.; Nozdrin, A.A.; Obraztsov, V. F.; Olshevsky, A.G.; Ostrick, M.; Padee, A.; Pagano, P.; Panebianco, S.; Panzieri, D.; Paul, S.; Peshekhonov, D.V.; Peshekhonov, V.D.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V.A.; Pontecorvo, G.; Popov, A.A.; Pretz, J.; Procureur, S.; Quintans, C.; Ramos, S.; Reicherz, G.; Rondio, E.; Rozhdestvensky, A.M.; Ryabchikov, D.; Samoylenko, V.D.; Sandacz, A.; Santos, H.; Sapozhnikov, M.G.; Savin, I.A.; Schiavon, P.; Schill, C.; Schmitt, L.; Schroeder, W.; Seeharsch, D.; Seimetz, M.; Setter, D.; Shevchenko, O.Yu.; Siebert, H.-W.; Silva, L.; Sinha, L.; Sissakian, A.N.; Slunecka, M.; Smirnov, G.I.; Sozzi, F.; Srnka, Aleš; Stinzing, F.; Stolarski, M.; Sugonyaev, V.P.; Sulc, M.; Sulej, R.; Tchalishev, V.V.; Tessaro, S.; Tessarotto, F.; Teufel, A.; Tkatchev, L.G.; Trippel, S.; Venugopal, G.; Virius, M.; Vlassov, N.V.; Webb, R.; Weise, E.; Weitzel, Q.; Windmolders, R.; Wislicki, W.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Zhao, J.; Ziegler, R.; Zvyagin, A.

2007-01-01

Roč. 647, č. 1 (2007), s. 8-17 ISSN 0370-2693 R&D Projects: GA MŠk ME 492 Institutional research plan: CEZ:AV0Z20650511 Keywords : Deep inelastic scattering * Spin * Structure function * QCD analysis * A1 * g1 Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 4.189, year: 2007 http://www.sciencedirect.com/science/article/B6TVN-4MYVG5P-1/2/387d70e7f30fb736514de259c62118d9

High spin effects in superdense matter

International Nuclear Information System (INIS)

Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.

1978-04-01

A model of relativistic interacting superdense matter with vector, scalar and symmetric second rank tensor exchange is developed. The Green's functions of the model are solved in the self consistent Hartree approximation. The contributions of the symmetric second rank tensor are emphasized. It is found that these high spin contributions effect the superdense matter at densities just beyond those predicted to occur in neutron star matter or nuclear collisions. The spin-two effects do produce an unusual asymptotic dependence, p = - 1 / 3 epsilon. This effect is examined in a simple model of the early universe

Recent developments in high-spin calculations in atomic nuclei

International Nuclear Information System (INIS)

Szymanski, Z.

1980-01-01

A brief introduction to the recent achievements in the high-spin domain in nuclear physics is given. Results of the calculations in highly developed rotational bands in deformed nuclei, as well as the calculations in the structure of the yrast isomers are presented. The calculations fail in two aspects: local minima in the yrast line are not confirmed experimentally, the overall slope of the yrast line in 152 Dy is considerably overestimated. The calculations of the yrast line with new Woods-Saxon parameters are now in progress. The parameters are chosen to reproduce the large gap in the levels at proton number Z=64. (M.H.)

Proton radioactivity at non-collective prolate shape in high spin state of {sup 94}Ag

Energy Technology Data Exchange (ETDEWEB)

Aggarwal, Mamta, E-mail: mamta.a4@gmail.co [UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Mumbai 400 098 (India)

2010-10-11

We predict proton radioactivity and structural transitions in high spin state of an excited exotic nucleus near proton drip line in a theoretical framework and investigate the nature and the consequences of the structural transitions on separation energy as a function of temperature and spin. It reveals that the rotation of the excited exotic nucleus {sup 94}Ag at excitation energies around 6.7 MeV and angular momentum near 21h generates a rarely seen prolate non-collective shape and proton separation energy becomes negative which indicates proton radioactivity in agreement with the experimental results of Mukha et al. for {sup 94}Ag.

The spin-dependent structure function g1 of the deuteron

International Nuclear Information System (INIS)

Bueltmann, S.

1996-01-01

Results on the spin-dependent structure function g 1 d of the deuteron measured by the Spin Muon Collaboration at CERN are presented. They are based on deep-inelastic scattering of 190 GeV polarized muons off a polarized deuteron target in the kinematic range of 0.003 ≤ x Bj ≤ 0.7 and 1 GeV 2 ≤ Q 2 ≤ 60 GeV 2 . The structure function is found to be negative for small values of x Bj , while the proton structure function g 1 p measured earlier by the SMC is positive over the whole x Bj -range. The Bjorken sum rule is in good agreement with the first moments of the structure functions, while the Ellis-Jaffe sum rule is violated by more than three standard deviations for the deuteron measurement. (author)

Quantum interference measurement of spin interactions in a bio-organic/semiconductor device structure

Science.gov (United States)

Deo, Vincent; Zhang, Yao; Soghomonian, Victoria; Heremans, Jean J.

2015-03-01

Quantum interference is used to measure the spin interactions between an InAs surface electron system and the iron center in the biomolecule hemin in nanometer proximity in a bio-organic/semiconductor device structure. The interference quantifies the influence of hemin on the spin decoherence properties of the surface electrons. The decoherence times of the electrons serve to characterize the biomolecule, in an electronic complement to the use of spin decoherence times in magnetic resonance. Hemin, prototypical for the heme group in hemoglobin, is used to demonstrate the method, as a representative biomolecule where the spin state of a metal ion affects biological functions. The electronic determination of spin decoherence properties relies on the quantum correction of antilocalization, a result of quantum interference in the electron system. Spin-flip scattering is found to increase with temperature due to hemin, signifying a spin exchange between the iron center and the electrons, thus implying interactions between a biomolecule and a solid-state system in the hemin/InAs hybrid structure. The results also indicate the feasibility of artificial bioinspired materials using tunable carrier systems to mediate interactions between biological entities.

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

OpenAIRE

Palotás, Krisztián; Rózsa, Levente; Szunyogh, László

2018-01-01

Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport v...

Long-lived nanosecond spin coherence in high-mobility 2DEGs confined in double and triple quantum wells

Energy Technology Data Exchange (ETDEWEB)

Ullah, S.; Gusev, G. M.; Hernandez, F. G. G., E-mail: felixggh@if.usp.br [Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, CEP 05315-970 São Paulo, SP (Brazil); Bakarov, A. K. [Institute of Semiconductor Physics and Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

2016-06-07

We investigated the spin coherence of high-mobility two-dimensional electron gases confined in multilayer GaAs quantum wells. The dynamics of the spin polarization was optically studied using pump-probe techniques: time-resolved Kerr rotation and resonant spin amplification. For double and triple quantum wells doped beyond the metal-to-insulator transition, the spin-orbit interaction was tailored by the sample parameters of structural symmetry (Rashba constant), width, and electron density (Dresselhaus linear and cubic constants) which allow us to attain long dephasing times in the nanoseconds range. The determination of the scales, namely, transport scattering time, single-electron scattering time, electron-electron scattering time, and spin polarization decay time further supports the possibility of using n-doped multilayer systems for developing spintronic devices.

Nuclear structure at high angular momentum

International Nuclear Information System (INIS)

Stephens, F.S.

1976-08-01

There is considerable interest in high angular-momentum states of nuclei, and some recent progress in three areas is discussed. Part I considers transitional nuclei, where two types of rotational bands--decoupled and strongly coupled--are found to occur very frequently. These can be described by several collective models, but the required potential-energy surfaces seem to differ somewhat from those calculated microscopically. In Part II the processes that might cause backbending (irregularities in the rotational levels of certain nuclei) are discussed, and alignment of individual nucleons now seems to be the cause in most cases. The mixing of the ground band with this aligned band can be studied in some detail using Coulomb excitation with very heavy ions. Part III deals with the very high-spin states where effective moments of inertia have been obtained for spins up to 50h. Also structure has been seen in the spectra around these spin values which can be tentatively related to calculated shell effects. 74 references, 61 figures

The determination of the in situ structure by nuclear spin contrast variation

Energy Technology Data Exchange (ETDEWEB)

Stuhrmann, H.B. [GKSS Forschungszentrum, Geesthacht (Germany); Nierhaus, K.H. [Max-Planch-Institut fuer Molekulare Genetik, Berlin (Germany)

1994-12-31

Polarized neutron scattering from polarized nuclear spins in hydrogenous substances opens a new way of contrast variation. The enhanced contrast due to proton spin polarization was used for the in situ structure determination of tRNA of the functional complex of the E.coli ribosome.

The determination of the in situ structure by nuclear spin contrast variation

International Nuclear Information System (INIS)

Stuhrmann, H.B.; Nierhaus, K.H.

1994-01-01

Polarized neutron scattering from polarized nuclear spins in hydrogenous substances opens a new way of contrast variation. The enhanced contrast due to proton spin polarization was used for the in situ structure determination of tRNA of the functional complex of the E.coli ribosome

Spin-polarized spin-orbit-split quantum-well states in a metal film

Energy Technology Data Exchange (ETDEWEB)

Varykhalov, Andrei; Sanchez-Barriga, Jaime; Gudat, Wolfgang; Eberhardt, Wolfgang; Rader, Oliver [BESSY Berlin (Germany); Shikin, Alexander M. [St. Petersburg State University (Russian Federation)

2008-07-01

Elements with high atomic number Z lead to a large spin-orbit coupling. Such materials can be used to create spin-polarized electronic states without the presence of a ferromagnet or an external magnetic field if the solid exhibits an inversion asymmetry. We create large spin-orbit splittings using a tungsten crystal as substrate and break the structural inversion symmetry through deposition of a gold quantum film. Using spin- and angle-resolved photoelectron spectroscopy, it is demonstrated that quantum-well states forming in the gold film are spin-orbit split and spin polarized up to a thickness of at least 10 atomic layers. This is a considerable progress as compared to the current literature which reports spin-orbit split states at metal surfaces which are either pure or covered by at most a monoatomic layer of adsorbates.

Recent COMPASS results on the nucleon longitudinal spin structure and QCD fits

Directory of Open Access Journals (Sweden)

Andrieux Vincent

2014-01-01

Full Text Available The latest measurements of the proton longitudinal spin structure function, ɡ1p, in the deep inelastic (DIS regime are presented. They improve the statistical accuracy of the existing data and extend the kinematic domain to a lower value of x and higher values of Q2. A global NLO QCD fit of all ɡ1 world data on the proton, deuteron and neutron has been achieved. The results give a quantification of the quark spin contribution to the nucleon spin, 0.26 < ΔΣ < 0.34 at 3 (GeV/c2 in M̅S̅ scheme. The errors are dominated by the uncertainty on the shape of the functional forms assumed in the fit. A new verification of the fundamental Bjorken sum rule is obtained at a 9% level, using only COMPASS ɡ1 proton and deuteron measurements. Preliminary results of a reevaluation of the gluon polarization Δɡ/ɡ are presented. The analysis is based on double spin asymmetry of high-pT hadron production cross-sections in the DIS regime. A positive value of 〈Δɡ/ɡ〉 = 0.113 ± 0.038 ± 0.035 is obtained at leading order at x ~ 0.1. In parallel, the double spin asymmetry in the photoproduction regime is also studied. Finally, preliminary results on quark fragmentation functions into pions extracted from a LO fit of pion multiplicities in semi-inclusive DIS are presented.

Level structure of 68149Er81 and high-spin isomerism in proton-rich N=81, 82, 83 nuclei

International Nuclear Information System (INIS)

Broda, R.; Daly, P.J.; McNeill, J.; Janssens, R.V.F.; Radford, D.C.

1987-01-01

The level structure of the N=81 nucleus 149 Er has been studied by γ-ray spectroscopy following the reaction 92 Mo+255 MeV 60 Ni. Yrast levels in 149 Er are established up to ≅ 3.3 MeV, including 0.61 and 4.8 μs isometric states. Most of the observed levels are interpreted as seniority-three states arising from the coupling of s 1/2 , d 3/2 and h 11/2 neutron holes with πh n 11/2 . Isomers identified in the reaction 96 Ru+255 MeV 58 Ni are tentatively assigned to 151 Yb. The B(E2) values of high-spin isomers in Z=66-70, N=81-83 nuclei are surveyed. (orig.)

Spin-ice behavior of three-dimensional inverse opal-like magnetic structures: Micromagnetic simulations

Science.gov (United States)

Dubitskiy, I. S.; Syromyatnikov, A. V.; Grigoryeva, N. A.; Mistonov, A. A.; Sapoletova, N. A.; Grigoriev, S. V.

2017-11-01

We perform micromagnetic simulations of the magnetization distribution in inverse opal-like structures (IOLS) made from ferromagnetic materials (nickel and cobalt). It is shown that the unit cell of these complex structures, whose characteristic length is approximately 700 nm, can be divided into a set of structural elements some of which behave like Ising-like objects. A spin-ice behavior of IOLS is observed in a broad range of external magnetic fields. Numerical results describe successfully the experimental hysteresis curves of the magnetization in Ni- and Co-based IOLS. We conclude that ferromagnetic IOLS can be considered as the first realization of three-dimensional artificial spin ice. The problem is discussed of optimal geometrical properties and material characteristics of IOLS for the spin-ice rule fulfillment.

Simplicity of state and overlap structure in finite-volume realistic spin glasses

International Nuclear Information System (INIS)

Newman, C.M.; Stein, D.L.

1998-01-01

We present a combination of heuristic and rigorous arguments indicating that both the pure state structure and the overlap structure of realistic spin glasses should be relatively simple: in a large finite volume with coupling-independent boundary conditions, such as periodic, at most a pair of flip-related (or the appropriate number of symmetry-related in the non-Ising case) states appear, and the Parisi overlap distribution correspondingly exhibits at most a pair of δ functions at ±q EA . This rules out the nonstandard mean-field picture introduced by us earlier, and when combined with our previous elimination of more standard versions of the mean-field picture, argues against the possibility of even limited versions of mean-field ordering in realistic spin glasses. If broken spin-flip symmetry should occur, this leaves open two main possibilities for ordering in the spin glass phase: the droplet-scaling two-state picture, and the chaotic pairs many-state picture introduced by us earlier. We present scaling arguments which provide a possible physical basis for the latter picture, and discuss possible reasons behind numerical observations of more complicated overlap structures in finite volumes. copyright 1998 The American Physical Society

Local spin structure of the α -RuCl3 honeycomb-lattice magnet observed via muon spin rotation/relaxation

Science.gov (United States)

Yamauchi, Ichihiro; Hiraishi, Masatoshi; Okabe, Hirotaka; Takeshita, Soshi; Koda, Akihiro; Kojima, Kenji M.; Kadono, Ryosuke; Tanaka, Hidekazu

2018-04-01

We report a muon spin rotation/relaxation (μ SR ) study of single-crystalline samples of the α -RuCl3 honeycomb magnet, which is presumed to be a model compound for the Kitaev-Heisenberg interaction. It is inferred from magnetic susceptibility and specific-heat measurements that the present samples exhibit successive magnetic transitions at different critical temperatures TN with decreasing temperature, eventually falling into the TN=7 K antiferromagnetic (7 K) phase that has been observed in only single-crystalline specimens with the least stacking fault. Via μ SR measurements conducted under a zero external field, we show that such behavior originates from a phase separation induced by the honeycomb plane stacking fault, yielding multiple domains with different TN's. We also perform μ SR measurements under a transverse field in the paramagnetic phase to identify the muon site from the muon-Ru hyperfine parameters. Based on a comparison of the experimental and calculated internal fields at the muon site for the two possible spin structures inferred from neutron diffraction data, we suggest a modulated zigzag spin structure for the 7 K phase, with the amplitude of the ordered magnetic moment being significantly reduced from that expected for the orbital quenched spin-1/2 state.

Thermal spin current generation and spin transport in Pt/magnetic-insulator/Py heterostructures

Science.gov (United States)

Chen, Ching-Tzu; Safranski, Christopher; Krivorotov, Ilya; Sun, Jonathan

Magnetic insulators can transmit spin current via magnon propagation while blocking charge current. Furthermore, under Joule heating, magnon flow as a result of the spin Seeback effect can generate additional spin current. Incorporating magnetic insulators in a spin-orbit torque magnetoresistive memory device can potentially yield high switching efficiencies. Here we report the DC magneto-transport studies of these two effects in Pt/magnetic-insulator/Py heterostructures, using ferrimagnetic CoFexOy (CFO) and antiferromagnet NiO as the model magnetic insulators. We observe the presence and absence of the inverse spin-Hall signals from the thermal spin current in Pt/CFO/Py and Pt/NiO/Py structures. These results are consistent with our spin-torque FMR linewidths in comparison. We will also report investigations into the magnetic field-angle dependence of these observations.

Electron refrigeration in hybrid structures with spin-split superconductors

Science.gov (United States)

Rouco, M.; Heikkilä, T. T.; Bergeret, F. S.

2018-01-01

Electron tunneling between superconductors and normal metals has been used for an efficient refrigeration of electrons in the latter. Such cooling is a nonlinear effect and usually requires a large voltage. Here we study the electron cooling in heterostructures based on superconductors with a spin-splitting field coupled to normal metals via spin-filtering barriers. The cooling power shows a linear term in the applied voltage. This improves the coefficient of performance of electron refrigeration in the normal metal by shifting its optimum cooling to lower voltage, and also allows for cooling the spin-split superconductor by reverting the sign of the voltage. We also show how tunnel coupling spin-split superconductors with regular ones allows for a highly efficient refrigeration of the latter.

Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling

Science.gov (United States)

Liu, Yan; Yu, Li; Jia, Xiaowen; Zhao, Jianzhou; Weng, Hongming; Peng, Yingying; Chen, Chaoyu; Xie, Zhuojin; Mou, Daixiang; He, Junfeng; Liu, Xu; Feng, Ya; Yi, Hemian; Zhao, Lin; Liu, Guodong; He, Shaolong; Dong, Xiaoli; Zhang, Jun; Xu, Zuyan; Chen, Chuangtian; Cao, Gang; Dai, Xi; Fang, Zhong; Zhou, X. J.

2015-08-01

The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations.

Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling.

Science.gov (United States)

Liu, Yan; Yu, Li; Jia, Xiaowen; Zhao, Jianzhou; Weng, Hongming; Peng, Yingying; Chen, Chaoyu; Xie, Zhuojin; Mou, Daixiang; He, Junfeng; Liu, Xu; Feng, Ya; Yi, Hemian; Zhao, Lin; Liu, Guodong; He, Shaolong; Dong, Xiaoli; Zhang, Jun; Xu, Zuyan; Chen, Chuangtian; Cao, Gang; Dai, Xi; Fang, Zhong; Zhou, X J

2015-08-12

The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations.

Micro-nanofibers with hierarchical structure by bubbfil-spinning

Directory of Open Access Journals (Sweden)

Liu Peng

2015-01-01

Full Text Available Bubbfil spinning is used to fabricate micro/nanofibers with hierarchical structure. The wall of a polymer film is attenuated unevenly by a blowing air. The burst of the bubble results in film fragments with different thickness, as a result, different sizes of fibers are obtained.

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

Shell structure in superdeformed nuclei at high rotational frequencies

International Nuclear Information System (INIS)

Ploszajczak, M.

1980-01-01

Properties of the shell structure in superdeformed nuclei at high rotational frequencies are discussed. Moreover, stability of the high spin compound nucleus with respect to the fission and the emission of light particles is investigated. (author)

Structure of large spin expansion of anomalous dimensions at strong coupling

International Nuclear Information System (INIS)

Beccaria, M.; Forini, V.; Tirziu, A.; Tseytlin, A.A.

2009-01-01

The anomalous dimensions of planar N=4 SYM theory operators like tr(ΦD + S Φ) expanded in large spin S have the asymptotics γ=flnS+f c +1/S (f 11 lnS+f 10 )+..., where f (the universal scaling function or cusp anomaly), f c and f mn are given by power series in the 't Hooft coupling λ. The subleading coefficients appear to be related by the so-called functional relation and parity (reciprocity) property of the function expressing γ in terms of the conformal spin of the collinear group. Here we study the structure of such large spin expansion at strong coupling via AdS/CFT, i.e. by using the dual description in terms of folded spinning string in AdS 5 . The large spin expansion of the classical string energy happens to have exactly the same structure as that of γ in the perturbative gauge theory. Moreover, the functional relation and the reciprocity constraints on the coefficients are also satisfied. We compute the leading string 1-loop corrections to the coefficients f c , f 11 , f 10 and verify the functional/reciprocity relations at subleading 1/(√(λ)) order. This provides a strong indication that these relations hold not only in weak coupling (gauge-theory) but also in strong coupling (string-theory) perturbative expansions

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

International Nuclear Information System (INIS)

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

2016-01-01

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.

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

Energy Technology Data Exchange (ETDEWEB)

Sirohi, Anshu; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Sheet, Goutam, E-mail: goutam@iisermohali.ac.in [Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli PO 140306 (India); Singh, Chandan K.; Kabir, Mukul [Department of Physics, Indian Institute of Science Education and Research, Pune 411008 (India); Thakur, Gohil S.; Haque, Zeba; Gupta, L. C. [Department of Chemistry, Indian Institute of Technology, New Delhi 110016 (India); Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, New Delhi 110016 (India); Institute of Nano Science & Technology, Mohali 160064 (India)

2016-06-13

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.

The two-component spin-fermion model for high-Tc cuprates: its applications in neutron scattering and ARPES experiments

International Nuclear Information System (INIS)

Bang, Yunkyu

2012-01-01

Motivated by neutron scattering experiments in high-T c cuprates, we propose the two-component spin-fermion model as a minimal phenomenological model, which has both local spins and itinerant fermions as independent degrees of freedom (d.o.f.). Our calculations of the dynamic spin correlation function provide a successful description of the puzzling neutron experiment data and show that: (i) the upward dispersion branch of magnetic excitations is mostly due to local spin excitations; (ii) the downward dispersion branch is from collective particle-hole excitations of fermions; and (iii) the resonance mode is a mixture of both d.o.f. Using the same model with the same set of parameters, we calculated the renormalized quasiparticle (q.p.) dispersion and successfully reproduced one of the key features of the angle-resolved photoemission spectroscopy (ARPES) experiments, namely the high-energy kink structure in the fermion q.p. dispersion, thus supporting the two-component spin-fermion phenomenology. (paper)

Quaternary structure and spin state of human fetal methemoglobin

International Nuclear Information System (INIS)

Chevion, M.; Navok, T.; Ilan, Y.A.; Czapski, G.

1981-01-01

Using the pulse-radiolysis technique, solutions of fetal human methemoglobin were irradiated in order to reduce a single heme-iron within the protein tetramers. The valence-hybrids thus formed ere reacted wjth oxygen. Kinetics of the reactions were studied. The effects of p and inositol-hexaphosphate (IHP) were examined. The kinetics of the ligation of oxygen to stripped valence-hybrids showed a single-phase behaviour at the pH range 7-9. As the pH was lowered below 6.5, a second slower phase became apparent. This slow phase consisted of approximately 50% at pH 5.8. In the presence of IHP above pH 7.4, the kinetics of oxygen-binding was of a single-phase. As the pH was lowered a transition to a second, slower phase was noticed. Below pH 7 the slower phase was the only detectable one. The analysis of the relative contribution of the faster phase to the total reaction, as a function of the pH, showed a typical sigmoidal transition curve characterized by a pK = 7.2 and a Hill parameter n = 3.06. On this basis it is concluded that stripped, fetal human methemoglobin resides in an R quaternary structure while the presence of IHP stabilizes the T structure at pH below 7.2. The switch between the high spin aquomet- and the low spin hydroxymet-derivatives of adult and fetal human hemoglobins was studied optically in detail. These switches were found to be only slightly affected by IHP, and exhibited very low cooperativity (pK = 8.04; n = 1.1 and pK = 8.10; n = 1.3 for adult methemoglobin when stripped and in the presence of IHP, respectively; pK = 8.18; n = 1.11 and pK = 8.21; n = 1.28 for fetal methemoglobin when stripped and in the presence of IHP, respectively). These findings lead to the conclusion that the transition between quaternary structures in either human or fetal methemoglobins is not coupled to the switch of the spin state of the ferric heme. (author)

Direct observation of the edge spin structure and chain length dependence of a finite haldane chain by high field ESR measurements

International Nuclear Information System (INIS)

Yoshida, Makoto; Ohta, Hitoshi; Ito, Toshimitsu; Ajiro, Yoshitami

2006-01-01

We have performed high field and multi-frequency ESR measurements of finite length S=1 antiferromagnetic chains in Y 2 BaNi 0.96 Mg 0.04 O 5 . Owing to the high spectral resolution by high fields and high frequencies, observed ESR signals can be separated into the contributions of the finite chains with various chain lengths. Our results clearly show that the edge spins actually interact with each other through the quantum spin chain and the interaction depends on the chain length N. (author)

High-Spin States in Odd-Odd N=Z {sup 46}V

Energy Technology Data Exchange (ETDEWEB)

O' Leary, C.D.; Bentley, M.A.; Appelbe, D.E.; Bark, R.A.; Cullen, D.M.; Erturk, S.; Maj. A.; Sheikh, J.A.; Warner, D.D.

1999-12-31

High-spin states up to the F{sub 7/2}-shell band termination at J{pi}=15+ have been observed for the first time in the odd-odd N=Z=23 nucleous {sup 46}V. The new level scheme has two separate structures corresponding to spherical and prolate shapes. A rotational band has very similar energies to the yrast sequence in {sup 46}Ti and is therefore assumed to be a T=1 configuration.

Observation of high-spin mixed oxidation state of cobalt in ceramic Co3TeO6

Science.gov (United States)

Singh, Harishchandra; Ghosh, Haranath; Chandrasekhar Rao, T. V.; Sinha, A. K.; Rajput, Parasmani

2014-12-01

We report coexistence of high spin Co3+ and Co2+ in ceramic Co3TeO6 using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co2+ and Co3+as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ˜1.26 eV between eg and t2g states, suggesting a mixture of high spin states of both Co2+ and Co3+. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (TN1 ˜ 29 K and TN2 ˜ 18 K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co2+), supports our inference that Co3+ exists in high spin state. Furthermore, we show that both Co2+ and Co3+ being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.

Structure of high-resolution NMR spectra

CERN Document Server

Corio, PL

2012-01-01

Structure of High-Resolution NMR Spectra provides the principles, theories, and mathematical and physical concepts of high-resolution nuclear magnetic resonance spectra.The book presents the elementary theory of magnetic resonance; the quantum mechanical theory of angular momentum; the general theory of steady state spectra; and multiple quantum transitions, double resonance and spin echo experiments.Physicists, chemists, and researchers will find the book a valuable reference text.

First example of a high-level correlated calculation of the indirect spin-spin coupling constants involving tellurium

DEFF Research Database (Denmark)

Rusakov, Yury Yu; Krivdin, Leonid B.; Østerstrøm, Freja From

2013-01-01

This paper documents a 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 the medium sized organotellurium molecules. The 125Te-1H spin-spin coupling...... constants of tellurophene and divinyl telluride were calculated at the SOPPA and DFT levels in a good agreement with experiment. 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 methods show much better performance as compared to 15 those of DFT, if relativistic effects calculated within the ZORA scheme are taken into account. Vibrational and solvent corrections are next to negligible, while...

Toward the fourth dimension of membrane protein structure: insight into dynamics from spin-labeling EPR spectroscopy.

Science.gov (United States)

McHaourab, Hassane S; Steed, P Ryan; Kazmier, Kelli

2011-11-09

Trapping membrane proteins in the confines of a crystal lattice obscures dynamic modes essential for interconversion between multiple conformations in the functional cycle. Moreover, lattice forces could conspire with detergent solubilization to stabilize a minor conformer in an ensemble thus confounding mechanistic interpretation. Spin labeling in conjunction with electron paramagnetic resonance (EPR) spectroscopy offers an exquisite window into membrane protein dynamics in the native-like environment of a lipid bilayer. Systematic application of spin labeling and EPR identifies sequence-specific secondary structures, defines their topology and their packing in the tertiary fold. Long range distance measurements (60 Å-80 Å) between pairs of spin labels enable quantitative analysis of equilibrium dynamics and triggered conformational changes. This review highlights the contribution of spin labeling to bridging structure and mechanism. Efforts to develop methods for determining structures from EPR restraints and to increase sensitivity and throughput promise to expand spin labeling applications in membrane protein structural biology. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spin structure of the 3He from the dd → 3Hen reaction

International Nuclear Information System (INIS)

Ladygin, V.P.; Ladygina, N.B.

1995-01-01

The polarization observables in the reaction dd → 3 Hen are considered. Their high sensitivity to the 3 He wave function at short distances is shown. Using of both polarized target and beam allows to extend sufficiently the number of possible experiments and to separate 3 He structure from the reaction mechanisms using different relative orientations of initial deuteron spins. 27 refs., 5 figs

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

Science.gov (United States)

Palotás, Krisztián; Rózsa, Levente; Szunyogh, László

2018-05-01

Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque, are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport vectors is demonstrated that enables the estimation of tunneling spin transport properties based on experimentally measured SP-STM images. A considerable tunability of the spin transport vectors by the involved spin polarizations is also highlighted. These possibilities and the combined theory of tunneling charge and vector spin transport pave the way for gaining deep insight into electric-current-induced tunneling spin transport properties in SP-STM and to the related dynamics of complex magnetic textures at surfaces.

Preferential spin canting in nanosize zinc ferrite

Energy Technology Data Exchange (ETDEWEB)

Pandey, Brajesh, E-mail: bpandey@gmail.com [Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Pune 411112 (India); Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil); Litterst, F.J. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil); Institut für Physik der Kondensierten Materie,Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig (Germany); Baggio-Saitovitch, E.M. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil)

2015-07-01

Zinc ferrite nanoparticles powder with average size of 10.0±0.5 nm was synthesized by the citrate precursor route. We studied the structural and magnetic properties using X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. X-ray diffraction patterns show that the synthesized zinc ferrite possesses good spinel structure. Both Mössbauer and magnetization data indicate superparamagnetic ferrimagnetic particles at room temperature. The magnetic behavior is determined by a considerable degree of cation inversion with Fe{sup III} in tetrahedral A-sites. Mössbauer spectroscopy at low temperature and in high applied magnetic field reveals that A-site spins are aligned antiparallel to the applied field with some possible angular scatter whereas practically all octahedral B-site spins are canted contrasting some earlier reported partial B-site spin canting in nanosize zinc ferrite. Deviations from the antiferromagnetic arrangement of B-site spins are supposed to be caused by magnetic frustration effects. - Highlights: • Spinel structure ZnFe{sub 2}O{sub 4} nanoparticles in the uniform size range of 10.0±0.5 nm have been synthesized using the citrate precursor route. • Canting of the spins of A- and B-sublattice sites has been studied by low temperature and high magnetic field Mössbauer spectroscopy. • A-site spins are aligned antiparallel to the applied field with only small angular scatter. • B-site spins are strongly canted in contrast to earlier quoted only partial canting. • B site spin structure deviates significantly from a collinear antiferromagnetic arrangement.

Topics on frustrated spin systems and high-temperature superconductors

International Nuclear Information System (INIS)

Lu Yong.

1990-01-01

The numerical study of frustrated spin systems using the Monte Carlo simulation method and the analytic study of fluctuation phenomenon of the thermoelectric power near the superconducting transition using Green's function techniques are presented. The first frustrated system considered is the B-site antiferromagnetic (AF) spinel. Based on an Ising model, various thermodynamic and magnetic properties were studied for both the fully frustrated structure and partially frustrated cases of a small tetragonal distortion. When fully frustrated, an interesting short-range order and some unusual scaling behavior were obtained. The other frustrated spin system studied is the magnetic phase of YBa 2 Cu 3 O 6+x via a classical spin model, with appropriate anisotropic exchange couplings and randomly located spins of distribution probability as a function of x. There is a first order boundary between Type 1 and Type 2 in the Ising case, while there is no real phase boundary in the cases of continuous spin. In the study on the thermopower fluctuation, the thermopower was determined by the linear response of the electric and heat currents to an electric field, and the linear responses were in turn calculated from correlation functions of the current

Low temperature spin dynamics and high pressure effects in frustrated pyrochlores

Science.gov (United States)

Mirebeau, Isabelle

2008-03-01

Frustrated pyrochlores R2M2O7, where R^3+ is a rare earth and M^4+ a transition or sp metal ion, show a large variety of exotic magnetic states due to the geometrical frustration of the pyrochlore lattice, consisting of corner sharing tetrahedra for both R and M ions. Neutron scattering allows one to measure their magnetic ground state as well as the spin fluctuations, in a microscopic way. An applied pressure may change the subtle energy balance between magnetic interactions, inducing new magnetic states. In this talk, I will review recent neutron results on Terbium pyrochlores, investigated by high pressure neutron diffraction and inelastic neutron scattering. Tb2M2O7 pyrochlores show respectively a spin liquid state for M=Ti [1], an ordered spin ice state for M= Sn [2], and a spin glass state with chemical order for M=Mo [3]. In Tb2Ti2O7 spin liquid, where only Tb^3+ ions are magnetic, an applied pressure induces long range antiferromagnetic order due to a small distortion of the lattice and magneto elastic coupling [4]. In Tb2Sn2O7, the substitution of Ti^4+ by the bigger Sn^4+ ion expands the lattice, inducing a long range ordered ferromagnetic state, with the local structure of a spin ice [2] and unconventional spin fluctuations [2,5]. The local ground state and excited crystal field states of the Tb^3+ ion were recently investigated by inelastic neutron scattering in both compounds [6]. Tb2Mo2O7, where Mo^4+ ions are also magnetic, shows an even more rich behaviour, due to the complex interaction between frustrated Tb and Mo lattices, having respectively localized and itinerant magnetism. In Tb2Mo2O7 spin glass, the lattice expansion induced by Tb/La substitution yields an ordered ferromagnetic state, which transforms back to spin glass under applied pressure [7]. New data about the spin fluctuations in these compounds, as measured by inelastic neutron scattering, will be presented. The talk will be dedicated to the memory of Igor Goncharenko, a renowned

High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

International Nuclear Information System (INIS)

Galanakis, I.

2015-01-01

Half-metallic Co 2 MnSi 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 Co 2 MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co 2 MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co 2 MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices

Structure and properties of quarternary and tetragonal Heusler compounds for spintronics and spin transver torque applications

Energy Technology Data Exchange (ETDEWEB)

Zamani, Vajiheh Alijani

2012-03-07

This work is divided into two parts: part 1 is focused on the prediction of half-metallicity in quaternary Heusler compounds and their potential for spintronic applications and part 2 on the structural properties of Mn{sub 2}-based Heusler alloys and tuning the magnetism of them from soft to hard-magnetic for spin-transfer torque applications. In part 1, three different series of quaternary Heusler compounds are investigated, XX'MnGa (X=Cu, Ni and X'=Fe,Co), CoFeMnZ (Z=Al,Ga,Si,Ge), and Co{sub 2-x}Rh{sub x}MnZ (Z=Ga,Sn,Sb). All of these quaternary compounds except CuCoMnGa are predicted to be half-metallic ferromagnets by ab-initio electronic structure calculations. In the XX'MnGa class of compounds, NiFeMnGa has a low Curie temperature for technological applications but NiCoMnGa with a high spin polarization, magnetic moment, and Curie temperature is an interesting new material for spintronics applications. All CoFeMnZ compounds exhibit a cubic Heusler structur and their magnetic moments are in fair agreement with the Slater-Pauling rule indicating the halfmetallicity and high spin polarization required for spintronics applications. Their high Curie temperatures make them suitable for utilization at room temperature and above. The structural investigation revealed that the crystal structure of all Co{sub 2-x}Rh{sub x}MnZ compounds aside from CoRhMnSn exhibit different types of anti-site disorder. The magnetic moments of the disordered compounds deviate from the Slater-Pauling rule indicating that 100% spin polarization are not realized in CoRhMnGa, CoRhMnSb, and Co{sub 0.5}Rh{sub 1.5}MnSb. Exchange of one Co in Co{sub 2}MnSn by Rh results in the stable, well-ordered compound CoRhMnSn. This exchange of one of the magnetic Co atoms by a non-magnetic Rh atom keeps the magnetic properties and half-metallicity intact. In part 2, two series of Mn{sub 2}-based Heusler alloys are investigated, Mn{sub 3-x}Co{sub x}Ga and Mn{sub 2-x}Rh{sub 1+x}Sn. It has been

High frequency spin torque oscillators with composite free layer spin valve

International Nuclear Information System (INIS)

Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

2016-01-01

We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

High frequency spin torque oscillators with composite free layer spin valve

Energy Technology Data Exchange (ETDEWEB)

Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

2016-07-15

We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

Self-consistent electronic structure of spin-polarized dilute magnetic semiconductor quantum wells

International Nuclear Information System (INIS)

Hong, S. P.; Yi, K. S.; Quinn, J. J.

2000-01-01

The electronic properties of spin-symmetry-broken dilute magnetic semiconductor quantum wells are investigated self-consistently at zero temperature. The spin-split subband structure and carrier concentration of modulation-doped quantum wells are examined in the presence of a strong magnetic field. The effects of exchange and correlations of electrons are included in a local-spin-density-functional approximation. We demonstrate that exchange correlation of electrons decreases the spin-split subband energy but enhances the carrier density in a spin-polarized quantum well. We also observe that as the magnetic field increases, the concentration of spin-down (majority) electrons increases but that of spin-up (minority) electrons decreases. The effect of orbital quantization on the in-plane motion of electrons is also examined and shows a sawtoothlike variation in subband electron concentrations as the magnetic-field intensity increases. The latter variation is attributed to the presence of ionized donors acting as the electron reservoir, which is partially responsible for the formation of the integer quantum Hall plateaus. (c) 2000 The American Physical Society

General structure of a two-body operator for spin-(1/2) particles

International Nuclear Information System (INIS)

Ershov, S.N.

2004-01-01

A direct derivation of the operator structure for two spin-(1/2) particles is presented subject to invariance under basic symmetries and Galilean frame transformation. The partial wave decomposition for coefficient functions, valid on- and off-shell, is explicitly deduced. The momentum transfer representation and angular momentum decomposition for general spin-dependent potentials are obtained

Bipolar spintronics: from spin injection to spin-controlled logic

International Nuclear Information System (INIS)

Zutic, Igor; Fabian, Jaroslav; Erwin, Steven C

2007-01-01

An impressive success of spintronic applications has been typically realized in metal-based structures which utilize magnetoresistive effects for substantial improvements in the performance of computer hard drives and magnetic random access memories. Correspondingly, the theoretical understanding of spin-polarized transport is usually limited to a metallic regime in a linear response, which, while providing a good description for data storage and magnetic memory devices, is not sufficient for signal processing and digital logic. In contrast, much less is known about possible applications of semiconductor-based spintronics and spin-polarized transport in related structures which could utilize strong intrinsic nonlinearities in current-voltage characteristics to implement spin-based logic. Here we discuss the challenges for realizing a particular class of structures in semiconductor spintronics: our proposal for bipolar spintronic devices in which carriers of both polarities (electrons and holes) contribute to spin-charge coupling. We formulate the theoretical framework for bipolar spin-polarized transport, and describe several novel effects in two- and three-terminal structures which arise from the interplay between nonequilibrium spin and equilibrium magnetization

Highly Efficient Spin-Current Operation in a Cu Nano-Ring

Science.gov (United States)

Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

2016-11-01

An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.

Structure of large spin expansion of anomalous dimensions at strong coupling

Energy Technology Data Exchange (ETDEWEB)

Beccaria, M. [Physics Department, Salento University and INFN, 73100 Lecce (Italy)], E-mail: matteo.beccaria@le.infn.it; Forini, V. [Humboldt-Universitaet zu Berlin, Institut fuer Physik, D-12489 Berlin (Germany)], E-mail: forini@aei.mpg.de; Tirziu, A. [Department of Physics, Purdue University, W. Lafayette, IN 47907-2036 (United States)], E-mail: atirziu@purdue.edu; Tseytlin, A.A. [Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)], E-mail: tseytlin@imperial.ac.uk

2009-05-01

The anomalous dimensions of planar N=4 SYM theory operators like tr({phi}D{sub +}{sup S}{phi}) expanded in large spin S have the asymptotics {gamma}=flnS+f{sub c}+1/S (f{sub 11}lnS+f{sub 10})+..., where f (the universal scaling function or cusp anomaly), f{sub c} and f{sub mn} are given by power series in the 't Hooft coupling {lambda}. The subleading coefficients appear to be related by the so-called functional relation and parity (reciprocity) property of the function expressing {gamma} in terms of the conformal spin of the collinear group. Here we study the structure of such large spin expansion at strong coupling via AdS/CFT, i.e. by using the dual description in terms of folded spinning string in AdS{sub 5}. The large spin expansion of the classical string energy happens to have exactly the same structure as that of {gamma} in the perturbative gauge theory. Moreover, the functional relation and the reciprocity constraints on the coefficients are also satisfied. We compute the leading string 1-loop corrections to the coefficients f{sub c}, f{sub 11}, f{sub 10} and verify the functional/reciprocity relations at subleading 1/({radical}({lambda})) order. This provides a strong indication that these relations hold not only in weak coupling (gauge-theory) but also in strong coupling (string-theory) perturbative expansions.

Orientation estimation algorithm applied to high-spin projectiles

International Nuclear Information System (INIS)

Long, D F; Lin, J; Zhang, X M; Li, J

2014-01-01

High-spin projectiles are low cost military weapons. Accurate orientation information is critical to the performance of the high-spin projectiles control system. However, orientation estimators have not been well translated from flight vehicles since they are too expensive, lack launch robustness, do not fit within the allotted space, or are too application specific. This paper presents an orientation estimation algorithm specific for these projectiles. The orientation estimator uses an integrated filter to combine feedback from a three-axis magnetometer, two single-axis gyros and a GPS receiver. As a new feature of this algorithm, the magnetometer feedback estimates roll angular rate of projectile. The algorithm also incorporates online sensor error parameter estimation performed simultaneously with the projectile attitude estimation. The second part of the paper deals with the verification of the proposed orientation algorithm through numerical simulation and experimental tests. Simulations and experiments demonstrate that the orientation estimator can effectively estimate the attitude of high-spin projectiles. Moreover, online sensor calibration significantly enhances the estimation performance of the algorithm. (paper)

Orientation estimation algorithm applied to high-spin projectiles

Science.gov (United States)

Long, D. F.; Lin, J.; Zhang, X. M.; Li, J.

2014-06-01

High-spin projectiles are low cost military weapons. Accurate orientation information is critical to the performance of the high-spin projectiles control system. However, orientation estimators have not been well translated from flight vehicles since they are too expensive, lack launch robustness, do not fit within the allotted space, or are too application specific. This paper presents an orientation estimation algorithm specific for these projectiles. The orientation estimator uses an integrated filter to combine feedback from a three-axis magnetometer, two single-axis gyros and a GPS receiver. As a new feature of this algorithm, the magnetometer feedback estimates roll angular rate of projectile. The algorithm also incorporates online sensor error parameter estimation performed simultaneously with the projectile attitude estimation. The second part of the paper deals with the verification of the proposed orientation algorithm through numerical simulation and experimental tests. Simulations and experiments demonstrate that the orientation estimator can effectively estimate the attitude of high-spin projectiles. Moreover, online sensor calibration significantly enhances the estimation performance of the algorithm.

Evolution of spin excitations in a gapped antiferromagnet from the quantum to the high-temperature limit

DEFF Research Database (Denmark)

Kenzelmann, M.; Cowley, R.A.; Buyers, W.J.L.

2002-01-01

We have mapped from the quantum to the classical limit the spin excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain system CsNiCl3 in its paramagnetic phase from T=5 to 200 K. Neutron scattering shows that the excitations are resonant and dispersive up to at least T=70 Ksimilar...... is in agreement with quantum Monte Carlo calculations for the spin-1 chain. xi is also consistent with the single mode approximation, suggesting that the excitations are short-lived single particle excitations. Below T=12 K where three-dimensional spin correlations are important, xi is shorter than predicted...... and the experiment is not consistent with the random phase approximation for coupled quantum chains. At T=200 K, the structure factor and second energy moment of the excitation spectrum are in excellent agreement with the high-temperature series expansion....

New high spin states and band termination in 83Y and 84Zr

International Nuclear Information System (INIS)

Johnson, T.D.; Aprahamian, A.; Lister, C.J.; Blumenthal, D.J.; Crowell, B.; Chowdhury, P.; Fallon, P.; Machiavelli, A.O.

1997-01-01

The gamma decay of high spin yrast states in 83 Y up to I π =59/2 + and 53/2 - have been observed using the reaction 58 Ni( 29 Si,3p) at 110 MeV and the Gammasphere Early Implementation Array. The level scheme has been substantially extended due to the observations of several new transitions in all of the bands. A sequence of transitions feeding into the positive parity yrast band above I π =47/2 + seems to be consistent with a noncollective oblate structure expected at these high spins. A similar cascade is found in the data for 84 Zr. A new forking of the favored negative parity band is found which may be due to neutron alignment polarizing the core to a different shape. This suggests that the open-quotes isomeric close-quote close-quote band in 83 Y, for which one more connecting transition was found, is of a similar nature to other high-K bands found in this region. Lifetime measurements in the unfavored negative parity band are consistent with cranking calculations which predict a nearly oblate shape with a deformation parameter β 2 ∼0.2. A qualitative analysis of line shapes at very high spins suggests the persistence of collectivity in the yrast sequence to the highest excitations seen. copyright 1997 The American Physical Society

The build up of the correlation between halo spin and the large-scale structure

Science.gov (United States)

Wang, Peng; Kang, Xi

2018-01-01

Both simulations and observations have confirmed that the spin of haloes/galaxies is correlated with the large-scale structure (LSS) with a mass dependence such that the spin of low-mass haloes/galaxies tend to be parallel with the LSS, while that of massive haloes/galaxies tend to be perpendicular with the LSS. It is still unclear how this mass dependence is built up over time. We use N-body simulations to trace the evolution of the halo spin-LSS correlation and find that at early times the spin of all halo progenitors is parallel with the LSS. As time goes on, mass collapsing around massive halo is more isotropic, especially the recent mass accretion along the slowest collapsing direction is significant and it brings the halo spin to be perpendicular with the LSS. Adopting the fractional anisotropy (FA) parameter to describe the degree of anisotropy of the large-scale environment, we find that the spin-LSS correlation is a strong function of the environment such that a higher FA (more anisotropic environment) leads to an aligned signal, and a lower anisotropy leads to a misaligned signal. In general, our results show that the spin-LSS correlation is a combined consequence of mass flow and halo growth within the cosmic web. Our predicted environmental dependence between spin and large-scale structure can be further tested using galaxy surveys.

Dynamical spin structure factors of α-RuCl3

Science.gov (United States)

Suzuki, Takafumi; Suga, Sei-ichiro

2018-03-01

Honeycomb-lattice magnet α-RuCl3 is considered to be a potential candidate of realizing Kitaev spin liquid, although this material undergoes a phase transition to the zigzag magnetically ordered state at T N ∼ 7 K. Quite recently, inelastic neutron-scattering experiments using single crystal α-RuCl3 have unveiled characteristic dynamical properties. We calculate dynamical spin structure factors of three ab-initio models for α-RuCl3 with an exact numerical diagonalization method. We also calculate temperature dependences of the specific heat by employing thermal pure quantum states. We compare our numerical results with the experiments and discuss characteristics obtained by using three ab-initio models.

Anatomy of a Spin: The Information-Theoretic Structure of Classical Spin Systems

Directory of Open Access Journals (Sweden)

Vikram S. Vijayaraghavan

2017-05-01

Full Text Available Collective organization in matter plays a significant role in its expressed physical properties. Typically, it is detected via an order parameter, appropriately defined for each given system’s observed emergent patterns. Recent developments in information theory, however, suggest quantifying collective organization in a system- and phenomenon-agnostic way: decomposing the system’s thermodynamic entropy density into a localized entropy, that is solely contained in the dynamics at a single location, and a bound entropy, that is stored in space as domains, clusters, excitations, or other emergent structures. As a concrete demonstration, we compute this decomposition and related quantities explicitly for the nearest-neighbor Ising model on the 1D chain, on the Bethe lattice with coordination number k = 3 , and on the 2D square lattice, illustrating its generality and the functional insights it gives near and away from phase transitions. In particular, we consider the roles that different spin motifs play (in cluster bulk, cluster edges, and the like and how these affect the dependencies between spins.

Spectroscopy of high spin states in sup(211,212,213)Fr

International Nuclear Information System (INIS)

Byrne, A.P.; Dracoulis, G.D.; Fahlander, C.; Hubel, H.; Poletti, A.R.; Stuchbery, A.E.; Gerl, J.; Davie, R.F.; Poletti, S.J.

1985-08-01

The level structures of 211 Fr, 212 Fr and 213 Fr have been observed to high spins, approx. 28(h/2π) (and excitation energies approx. 8 MeV) using a variety of gamma-ray spectroscopic techniques. The structure of these nuclides is discussed in terms of couplings of single particle states through empirical shell model calculations. Good agreement with experiment is obtained. In 212 Fr and 213 Fr core-excited configurations are required to explain the properties of the highest states. A number of long lived states were observed in each nucleus some of which decay by by enhanced E3 transitions. The E3 transition strengths are discussed

A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy barriers revealed by high-field electron spin resonance spectroscopy

International Nuclear Information System (INIS)

Bercu, V; Martinelli, M; Massa, C A; Pardi, L A; Leporini, D

2004-01-01

The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field electron spin resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy barriers for the rotational motion of the spin probe is unambiguously evidenced at both 240 and 270 K. The same shape for the distribution of the energy barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy barrier distribution of the spin probe is in the range of the estimates of the breadth of the PS energy barrier distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy barrier distribution agrees with the results from extreme-value statistics (Bouchaud and Mezard 1997 J. Phys. A: Math. Gen. 30 7997) and the trap model by Bouchaud and co-workers (1996 J. Phys. A: Math. Gen. 29 3847, 2001 Phys. Rev. B 64 104417). (letter to the editor)

Remnant magnetization of Fe8 high-spin molecules: X-ray magnetic circular dichroism at 300 mK

Science.gov (United States)

Letard, Isabelle; Sainctavit, Philippe; dit Moulin, Christophe Cartier; Kappler, Jean-Paul; Ghigna, Paolo; Gatteschi, Dante; Doddi, Bruno

2007-06-01

Fe8 high-spin molecules exhibit quantum spin tunneling at very low temperatures. Eight Fe3+ ions are sixfold coordinated and magnetically coupled through oxygen bridges. The net magnetization (MS=20 μB per molecule) results from competing antiferromagnetic interactions between the various Fe3+ ions (S =5/2). Because of the structural anisotropy of these molecules, the magnetization curve presents a hysteresis loop with staircases below 2 K. The staircases of the hysteresis loop are due to the quantum spin tunneling, which is temperature dependent for 400 mKmolecule. It has been possible to register an XMCD remnant signal, without magnetic field applied, at the iron L2,3 edges. XMCD coupled with ligand field multiplet calculations has allowed to determine the spin and orbit contributions to the magnetization of the Fe3+ ions.

Observation of a new high-spin isomer in 94Pd

International Nuclear Information System (INIS)

Brock, T. S.; Nara Singh, B. S.; Wadsworth, R.; Boutachkov, P.; Gorska, M.; Grawe, H.; Pietri, S.; Domingo-Pardo, C.; Caceres, L.; Engert, T.; Farinon, F.; Gerl, J.; Goel, N.; Kojuharov, I.; Kurz, N.; Nociforo, C.; Prochazka, A.; Schaffner, H.; Weick, H.; Braun, N.

2010-01-01

A second γ-decaying high-spin isomeric state, with a half-life of 197(22)ns, has been identified in the N=Z+2 nuclide 94 Pd as part of a stopped-beam Rare Isotope Spectroscopic INvestigation at GSI (RISING) experiment. Weisskopf estimates were used to establish a tentative spin/parity of 19 - , corresponding to the maximum possible spin of a negative parity state in the restricted (p 1/2 , g 9/2 ) model space of empirical shell model calculations. The reproduction of the E3 decay properties of the isomer required an extension of the model space to include the f 5/2 and p 3/2 orbitals using the CD-Bonn potential. This is the first time that such an extension has been required for a high-spin isomer in the vicinity of 100 Sn and reveals the importance of such orbits for understanding the decay properties of high-spin isomers in this region. However, despite the need for the extended model space for the E3 decay, the dominant configuration for the 19 - state remains (πp 1/2 -1 g 9/2 -3 ) 11 x (νg 9/2 -2 ) 8 . The half-life of the known, 14 + , isomer was remeasured and yielded a value of 499(13) ns.

Analysis of possibilities for a spin flip in high energy electron ring HERA

International Nuclear Information System (INIS)

Stres, S.; Pestotnik, R.

2007-01-01

In a high energy electron ring the spins of electrons become spontaneously polarized via the emission of spin-flip synchrotron radiation. By employing a radio frequency (RF) radial dipole field kicker, particle spin directions can be rotated slowly over many turns. A model which couples three dimensional spin motion and longitudinal particle motion was constructed to describe non-equilibrium spin dynamics in high energy electron storage rings. The effects of a stochastic synchrotron radiation on the orbital motion in the accelerator synchrotron plane and its influence on the spin motion are studied. The main contributions to the spin motion, the synchrotron oscillations and the stochastic synchrotron radiation, have different influence on the spin polarization reversal in different regions of the parameter space. The results indicate that polarization reversal might be obtained in high energy electron storage rings with a significant noise even with relatively small strengths of a perturbing magnetic field. The only experimental datum avaliable agrees with the model prediction, however further experimental data would be necessary to validate the model

High spin rotations of nuclei with the harmonic oscillator potential

International Nuclear Information System (INIS)

Cerkaski, M.; Szymanski, Z.

1978-01-01

Calculations of the nuclear properties at high angular momentum have been performed recently. They are based on the liquid drop model of a nucleus and/or on the assumption of the single particle shell structure of the nucleonic motion. The calculations are usually complicated and involve long computer codes. In this article we shall discuss general trends in fast rotating nuclei in the approximation of the harmonic oscillator potential. We shall see that using the Bohr Mottelson simplified version of the rigorous solution of Valatin one can perform a rather simple analysis of the rotational bands, structure of the yrast line, moments of inertia etc. in the rotating nucleus. While the precision fit to experimental data in actual nuclei is not the purpose of this paper, one can still hope to reach some general understanding within the model of the simple relations resulting in nuclei at high spin. (author)

Low Temperature Electrical Spin Injection from Highly Spin Polarized Co₂CrAl Heusler Alloy into p-Si.

Science.gov (United States)

Kar, Uddipta; Panda, J; Nath, T K

2018-06-01

The low temperature spin accumulation in p-Si using Co2CrAl/SiO2 tunnel junction has been investigated in detail. The heterojunction has been fabricated using electron beam evaporation (EBE) technique. The 3-terminal contacts in Hanle geometry has been made for spin transport measurements. The electrical transport properties have been investigated at different isothermal conditions in the temperature range of 10-300 K. The current-voltage characteristics of the junction shows excellent rectifying magnetic diode like behaviour in lower temperature range (below 200 K). At higher temperature, the junction shows nonlinear behaviour without rectifying characteristics. We have observed spin accumulation signal in p-Si semiconductor using SiO2/Co2CrAl tunnel junction in the low temperature regime (30-100 K). Hence the highly spin polarized Full Heusler alloys compounds, like Co2CrAl etc., are very attractive and can act as efficient tunnel device for spin injection in the area of spintronics devices in near future. The estimated spin life time is τ = 54 pS and spin diffusion length inside p-Si is LSD = 289 nm at 30 K for this heterostructure.

A study of manufacturing tubes with nano/ultrafine grain structure by stagger spinning

International Nuclear Information System (INIS)

Xia, Qinxiang; Xiao, Gangfeng; Long, Hui; Cheng, Xiuquan; Yang, Baojian

2014-01-01

Highlights: • Proposing a method of manufacturing tubes with nano/ultrafine crystal. • Obtaining the refined ferritic grains with an size of 500 nm after stagger spinning. • Obtaining the equiaxial ferritic grains with an size of 600 nm after annealing. - Abstract: A new method of manufacturing tubes with nano/ultrafine grain structure by stagger spinning and recrystallization annealing is proposed in this study. Two methods of the stagger spinning process are developed, the corresponding macroforming quality, microstructural evolution and mechanical properties of the spun tubes made of ASTM 1020 steel are analysed. The results reveal that a good surface smoothness and an improved spin-formability of spun parts can be obtained by the process combining of 3-pass spinning followed by a 580 °C × 0.5 h static recrystallization and 2-pass spinning with a 580 °C × 1 h static recrystallization annealing under the severe thinning ratio of wall thickness reduction. The ferritic grains with an average initial size of 50 μm are refined to 500 nm after stagger spinning under the 87% thinning ratio of wall thickness reduction. The equiaxial ferritic grains with an average size of 600 nm are generated through re-nucleation and grain growth by subsequent recrystallization annealing at 580 °C for 1 h heat preservation. The tensile strength of spun tubes has been founded to be proportional to the reciprocal of layer spacing of pearlite (LSP), and the elongation is inversely proportional to the reciprocal of LSP. This study shows that the developed method of stagger power spinning has the potential to be used to manufacture bulk metal components with nano/ultrafine grain structure

Magnetic structure and spin dynamics of the quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8

DEFF Research Database (Denmark)

Kawasaki, Yu; Gavilano, Jorge L.; Keller, Lukas

2011-01-01

,0,1), independent of external magnetic fields for fields below a critical value H-c(T). The ordered moments of 2.18 mu(B) per Co ion are aligned along the crystallographic c axis. Within the screw chains, along the c axis, the moments are arranged antiferromagnetically. In the basal planes the spins are arranged......We report a neutron diffraction and muon spin relaxation mu SR study of static and dynamical magnetic properties of BaCo2V2O8, a quasi-one-dimensional spin-chain system. A proposed model for the antiferromagnetic structure includes: a propagation vector (k) over right arrow (AF) = (0...

Review structure of silk by raman spectromicroscopy: from the spinning glands to the fibers.

Science.gov (United States)

Lefèvre, Thierry; Paquet-Mercier, François; Rioux-Dubé, Jean-François; Pézolet, Michel

2012-06-01

Raman spectroscopy has long been proved to be a useful tool to study the conformation of protein-based materials such as silk. Thanks to recent developments, linearly polarized Raman spectromicroscopy has appeared very efficient to characterize the molecular structure of native single silk fibers and spinning dopes because it can provide information relative to the protein secondary structure, molecular orientation, and amino acid composition. This review will describe recent advances in the study of the structure of silk by Raman spectromicroscopy. A particular emphasis is put on the spider dragline and silkworm cocoon threads, other fibers spun by orb-weaving spiders, the spinning dope contained in their silk glands and the effect of mechanical deformation. Taken together, the results of the literature show that Raman spectromicroscopy is particularly efficient to investigate all aspects of silk structure and production. The data provided can lead to a better understanding of the structure of the silk dope, transformations occurring during the spinning process, and structure and mechanical properties of native fibers. Copyright © 2011 Wiley Periodicals, Inc.

High spin cycles: topping the spin record for a single molecule verging on quantum criticality

Science.gov (United States)

Baniodeh, Amer; Magnani, Nicola; Lan, Yanhua; Buth, Gernot; Anson, Christopher E.; Richter, Johannes; Affronte, Marco; Schnack, Jürgen; Powell, Annie K.

2018-03-01

The cyclisation of a short chain into a ring provides fascinating scenarios in terms of transforming a finite array of spins into a quasi-infinite structure. If frustration is present, theory predicts interesting quantum critical points, where the ground state and thus low-temperature properties of a material change drastically upon even a small variation of appropriate external parameters. This can be visualised as achieving a very high and pointed summit where the way down has an infinity of possibilities, which by any parameter change will be rapidly chosen, in order to reach the final ground state. Here we report a mixed 3d/4f cyclic coordination cluster that turns out to be very near or even at such a quantum critical point. It has a ground state spin of S = 60, the largest ever observed for a molecule (120 times that of a single electron). [Fe10Gd10(Me-tea)10(Me-teaH)10(NO3)10].20MeCN forms a nano-torus with alternating gadolinium and iron ions with a nearest neighbour Fe-Gd coupling and a frustrating next-nearest neighbour Fe-Fe coupling. Such a spin arrangement corresponds to a cyclic delta or saw-tooth chain, which can exhibit unusual frustration effects. In the present case, the quantum critical point bears a `flatland' of tens of thousands of energetically degenerate states between which transitions are possible at no energy costs with profound caloric consequences. Entropy-wise the energy flatland translates into the pointed summit overlooking the entropy landscape. Going downhill several target states can be reached depending on the applied physical procedure which offers new prospects for addressability.

The spin structure of the nucleon

Energy Technology Data Exchange (ETDEWEB)

Le Goff, J.M

2005-02-15

The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*{delta}{sigma} + {delta}g + L{sub q} + L{sub g} where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L{sub q} and L{sub g} are the orbital momentum of the quark and the gluon respectively. The {delta}{sigma} contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization {delta}g/g and the so-called transversity. (A.C.)

The spin structure of the nucleon

International Nuclear Information System (INIS)

Le Goff, J.M.

2005-02-01

The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*ΔΣ + Δg + L q + L g where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L q and L g are the orbital momentum of the quark and the gluon respectively. The ΔΣ contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization Δg/g and the so-called transversity. (A.C.)

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

Science.gov (United States)

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.

High PT electronuclear reactions and spin observables

International Nuclear Information System (INIS)

Laget, J.M.

1990-01-01

The main arguments of the following topics are reviewed: the high transverse momentum exclusive reactions, the determination of various spin observables and the production of different flavours in reactions induced by real and virtual photons

Spin-orbit excitations and electronic structure of the putative Kitaev magnet α -RuCl3

Science.gov (United States)

Sandilands, Luke J.; Tian, Yao; Reijnders, Anjan A.; Kim, Heung-Sik; Plumb, K. W.; Kim, Young-June; Kee, Hae-Young; Burch, Kenneth S.

2016-02-01

Mott insulators with strong spin-orbit coupling have been proposed to host unconventional magnetic states, including the Kitaev quantum spin liquid. The 4 d system α -RuCl3 has recently come into view as a candidate Kitaev system, with evidence for unusual spin excitations in magnetic scattering experiments. We apply a combination of optical spectroscopy and Raman scattering to study the electronic structure of this material. Our measurements reveal a series of orbital excitations involving localized total angular momentum states of the Ru ion, implying that strong spin-orbit coupling and electron-electron interactions coexist in this material. Analysis of these features allows us to estimate the spin-orbit coupling strength, as well as other parameters describing the local electronic structure, revealing a well-defined hierarchy of energy scales within the Ru d states. By comparing our experimental results with density functional theory calculations, we also clarify the overall features of the optical response. Our results demonstrate that α -RuCl3 is an ideal material system to study spin-orbit coupled magnetism on the honeycomb lattice.

Structural features of spin-coated thin films of binary As{sub x}S{sub 100−x} chalcogenide glass system

Energy Technology Data Exchange (ETDEWEB)

Cook, J. [Austin Peay State University, Clarksville, TN 37075 (United States); Slang, S. [Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Golovchak, R. [Austin Peay State University, Clarksville, TN 37075 (United States); Jain, H. [International Materials Institute for New Functionality in Glass, Lehigh University, Bethlehem, PA 18015 (United States); Vlcek, M. [Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Kovalskiy, A., E-mail: kovalskyya@apsu.edu [Austin Peay State University, Clarksville, TN 37075 (United States)

2015-08-31

Spin-coating technology offers a convenient method for fabricating photostable chalcogenide glass thin films that are especially attractive for applications in IR optics. In this paper we report the structure of spin-coated As{sub x}S{sub 100−x} (x = 30, 35, 40) thin films as determined using high resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, especially in relation to composition (i.e. As/S ratio) and preparation process variables. It was observed that As atoms during preparation have a tendency to precipitate out in close to stoichiometric compositions. The mechanism of bonding between the inorganic matrix and organic residuals is discussed based on the experimental data. A weak interaction between S ions and amine-based clusters is proposed as the basis of structural organization of the organic–inorganic interface. - Highlights: • As–S spin-coated chalcogenide thin films with different As/S were fabricated. • XPS measurements support the cluster-like structure of spin-coated films. • As{sub 2}O{sub 3} was confirmed as the composition of precipitate formed during dissolution. • Lack of As–As bonds explains the observed photostability of the thin films.

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

DEFF Research Database (Denmark)

Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo

2013-01-01

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...

In-Beam Studies of High-Spin States in Mercury -183 and MERCURY-181

Science.gov (United States)

Shi, Detang

The high-spin states of ^{183 }Hg were studied by using the reaction ^{155}Gd(^{32}S, 4n)^{183}Hg at a beam energy of 160 MeV with the tandem-linac accelerator system and the multi-element gamma-ray detection array at Florida State University. Two new bands, consisting of stretched E2 transitions and connected by M1 inter-band transitions, were identified in ^{183}Hg. Several new levels were added to the previously known bands at higher spin. The spins and parities to the levels in ^{183}Hg were determined from the analysis of their DCO ratios and B(M1)/B(E2) ratios. While the two pairs of previously known bands in ^ {183}Hg were proposed to 7/2^ -[514] and 9/2^+ [624], the two new bands are assigned as the 1/2^-[521] ground state configuration based upon the systematics of Nilsson orbitals in this mass region. The 354-keV transition previously was considered to be an E2 transition and assigned as the only transition from a band which is built on an oblate deformed i_{13/2} isomeric state. However, our DCO ratio analysis indicates that the 354-keV gamma-ray is an M1 transition. This changes the decay pattern of the 9/2^+[624 ] prolate structure in ^ {183}Hg, so it is seen to feed only into the i_{13/2} isomer band head. Our knowledge of the mercury nuclei far from stability was then extended through an in-beam study of the reaction ^{144}Sm(^{40 }Ar, 3n)^{181}Hg by using the Fragment Mass Analyzer (FMA) and the ten-Compton-suppressed -germanium-detector system at Argonne National Laboratory. Band structures to high-spin states are established for the first time in ^{181}Hg in the present experiment. The observed level structure of ^{181}Hg is midway between those in ^{185}Hg and in ^{183}Hg. The experimental results are analyzed in the framework of the cranking shell model (CSM). Alternative theoretical explanations are also presented and discussed. Systematics of neighboring mercury isotopes and N = 103 isotones is analyzed.

Structural and electronic properties of Er-monopnictides under high pressure

International Nuclear Information System (INIS)

Pandit, Premlata; Srivastava, Vipul; Rajagopalan, M.; Sanyal, Sankar P.

2010-01-01

We present the results of theoretical calculations on the structural, magnetic and electronic properties of Er-monopnictides using self-consistent first principles tight-binding linear-muffin-tin-orbital (TB-LMTO) method within the atomic-sphere approximation (ASA). Both spin-polarized and non-spin-polarized calculations are performed to check the magnetic stability of these compounds. We find that ErN, ErP and ErAs are metallic in ferromagnetic (FM) phase in both the spin channels and stable in NaCl-type (B 1 ) structure at ambient pressure. We predict NaCl-type (B 1 ) to CsCl-type (B 2 ) structural phase transition in ErN, ErP and ErAs at pressures of 146.1, 60.2 and 53.2 GPa, respectively and remain metallic ferromagnetic at high pressure. We calculate equilibrium lattice constants (a), bulk modulus (B), magnetic moments (μ B ) and electronic properties of these compounds in B 1 and B 2 phases and compare with available experimental and theoretical results.

Spin structure of exchange biased heterostructures. Fe/MnF{sub 2} and Fe/FeF{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sahoo, B

2006-12-18

In this work, the {sup 57}Fe probe layer technique is used in order to investigate the depth- and temperature-dependent Fe-layer spin structure of exchange biased Fe/MnF{sub 2} and Fe/FeF{sub 2} (pseudo-twinned) antiferromagnetic (AFM) systems by conversion electron Moessbauer spectroscopy (CEMS) and nuclear resonant scattering (NRS) of synchrotron radiation. Two kinds of samples with a 10 A {sup 57}Fe probe layer directly at or 35 A away from the interface, labeled as interface and center sample, respectively, were studied in this work. The results obtained by CEMS for Fe/MnF{sub 2} suggests that, at 80 K, i.e., above T{sub N}=67 K of MnF{sub 2}, the remanent state Fe-layer spin structure of the two studied samples are slightly different due to their different microstructure. In the temperature range from 300 K to 80 K, the Fe-layer spin structure does not change just by zero-field cooling the sample in remanence. For Fe/FeF{sub 2}, a continuous non-monotonic change of the remanent-state Fe spin structure was observed by cooling from 300 K to 18 K. NRS of synchrotron radiation was used to investigate the temperature- and depth-dependent Fe-layer spin structure during magnetization reversal in pseudo-twinned Fe/MnF{sub 2}. A depthdependent Fe spin structure in an applied magnetic field (applied along the bisector of the twin domains) was observed at 10 K, where the Fe spins closer to the interface are not aligned along the field direction. The depth-dependence disappears at 150 K. (orig.)

Fully aligned high-spin states in 86Zr

International Nuclear Information System (INIS)

Doring, J.; Hohns, G.D.; Sylvan, G.N.

1995-01-01

To study multi-quasiparticle excitations and their interplay with collective degrees of freedom at very high spins, a new in-beam investigation of the even-even 86 Zr has been performed via the 58 Ni( 32 S,4p) reaction at 135 MeV using the early implementation of GAMMASPHERE combined with the 47π charged particle detector system MICROBALL. The yrast positive- and negative-parity sequences have been extended up to 30 + and 27 - levels, respectively. Calculations within the configuration-dependent shell-correction method using a cranked Nilsson potential have shown that the highest spins are built from the six g 9 /2 neutrons and at most four protons excited from the p 1/2 , p 3/2 , f 5/2 subshells to the g 9 /2 subshell at a small deformation. The 30 + and 27 - states are the highest possible fully-aligned states based on holes in the N = 3 shell. Higher spins can be built by promotion of one neutron from the g 9 /2 to the g 7 /2 subshell but with a quite high energy cost

Optical-coupling nuclear spin maser under highly stabilized low static field

Energy Technology Data Exchange (ETDEWEB)

Yoshimi, A., E-mail: yoshimi@ribf.riken.jp [RIKEN Nishina Center (Japan); Inoue, T.; Uchida, M.; Hatakeyama, N.; Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan)

2008-01-15

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in {sup 129}Xe atom is being developed.

Spin Hall magnetoresistance at high temperatures

International Nuclear Information System (INIS)

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

2015-01-01

The temperature dependence of spin Hall magnetoresistance (SMR) in Pt/Y 3 Fe 5 O 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

Interfacial symmetry of Co–Alq_3–Co hybrid structures for effective spin filtering

International Nuclear Information System (INIS)

Lam, Tu-Ngoc; Lai, Yu-Ling; Chen, Chih-Han; Chen, Po-Hung; Wei, Der-Hsin; Lin, Hong-Ji; Chen, C.T.; Sheu, Jeng-Tzong; Hsu, Yao-Jane

2015-01-01

Graphical abstract: - Highlights: • The spin interface at Alq_3/Co and Co/Alq_3 contacts was examined. • An interfacial symmetry was determined at Co–Alq_3–Co interfaces. • Spin-polarized N orbitals are induced within the Co atop Alq_3 hybridized interface. • The spin-filter role at the top contact interface of Alq_3/Co is proved. • Effective spin-filtering at Co–Alq_3–Co contacts was elucidated. - Abstract: Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq_3 adsorption on Co, Co/Alq_3) and the top contact (Co atop Alq_3, Alq_3/Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq_3 and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq_3/Co and Co/Alq_3 heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co–Alq_3–Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq_3 at both contacts, proving Alq_3 a unique and promising organic material for spin filtering in OSV.

Nanopatterned reconfigurable spin-textures for magnonics

Science.gov (United States)

Albisetti, E.; Petti, D.; Pancaldi, M.; Madami, M.; Tacchi, S.; Curtis, J.; King, W. P.; Papp, A.; Csaba, G.; Porod, W.; Vavassori, P.; Riedo, E.; Bertacco, R.

The control of spin-waves holds the promise to enable energy-efficient information transport and wave-based computing. Conventionally, the engineering of spin-waves is achieved via physically patterning magnetic structures such as magnonic crystals and micro-nanowires. We demonstrate a new concept for creating reconfigurable magnonic nanostructures, by crafting at the nanoscale the magnetic anisotropy landscape of a ferromagnet exchange-coupled to an antiferromagnet. By performing a highly localized field cooling with the hot tip of a scanning probe microscope, magnetic structures, with arbitrarily oriented magnetization and tunable unidirectional anisotropy, are patterned without modifying the film chemistry and topography. We demonstrate that, in such structures, the spin-wave excitation and propagation can be spatially controlled at remanence, and can be tuned by external magnetic fields. This opens the way to the use of nanopatterned spin-textures, such as domains and domain walls, for exciting and manipulating magnons in reconfigurable nanocircuits. Partially funded by the EC through project SWING (no. 705326).

Investigation of spin-polarized transport in GaAs nanostructures

Energy Technology Data Exchange (ETDEWEB)

Tierney, B D; Day, T E; Goodnick, S M [Department of Electrical Engineering and Center for Solid State Electronics Research Arizona State University, Tempe, AZ 85287-5706 (United States)], E-mail: brian.tierney@asu.edu

2008-03-15

A spin field effect transistor (spin-FET) has been fabricated that employs nanomagnets as components of quantum point contact (QPC) structures to inject spin-polarized carriers into the high-mobility two-dimensional electron gas (2DEG) of a GaAs quantum well and to detect them. A centrally-placed non-magnetic Rashba gate controls both the density of electrons in the 2DEG and the electronic spin precession. Initial results are presented for comparable device structures modeled with an ensemble Monte Carlo (EMC) method. In the EMC the temporal and spatial evolution of the ensemble carrier spin polarization is governed by a spin density matrix formalism that incorporates the Dresselhaus and Rashba contributions to the D'yakanov-Perel spin-flip scattering mechanism, the predominant spin scattering mechanism in AlGaAs/GaAs heterostructures from 77-300K.

Paramagnetic properties of the low- and high-spin states of yeast cytochrome c peroxidase

International Nuclear Information System (INIS)

Vanwetswinkel, Sophie; Nuland, Nico A. J. van; Volkov, Alexander N.

2013-01-01

Here we describe paramagnetic NMR analysis of the low- and high-spin forms of yeast cytochrome c peroxidase (CcP), a 34 kDa heme enzyme involved in hydroperoxide reduction in mitochondria. Starting from the assigned NMR spectra of a low-spin CN-bound CcP and using a strategy based on paramagnetic pseudocontact shifts, we have obtained backbone resonance assignments for the diamagnetic, iron-free protein and the high-spin, resting-state enzyme. The derived chemical shifts were further used to determine low- and high-spin magnetic susceptibility tensors and the zero-field splitting constant (D) for the high-spin CcP. The D value indicates that the latter contains a hexacoordinate heme species with a weak field ligand, such as water, in the axial position. Being one of the very few high-spin heme proteins analyzed in this fashion, the resting state CcP expands our knowledge of the heme coordination chemistry in biological systems

Paramagnetic properties of the low- and high-spin states of yeast cytochrome c peroxidase

Energy Technology Data Exchange (ETDEWEB)

Vanwetswinkel, Sophie; Nuland, Nico A. J. van; Volkov, Alexander N., E-mail: ovolkov@vub.ac.be [Vrije Universiteit Brussel, Jean Jeener NMR Centre, Structural Biology Brussels (Belgium)

2013-09-15

Here we describe paramagnetic NMR analysis of the low- and high-spin forms of yeast cytochrome c peroxidase (CcP), a 34 kDa heme enzyme involved in hydroperoxide reduction in mitochondria. Starting from the assigned NMR spectra of a low-spin CN-bound CcP and using a strategy based on paramagnetic pseudocontact shifts, we have obtained backbone resonance assignments for the diamagnetic, iron-free protein and the high-spin, resting-state enzyme. The derived chemical shifts were further used to determine low- and high-spin magnetic susceptibility tensors and the zero-field splitting constant (D) for the high-spin CcP. The D value indicates that the latter contains a hexacoordinate heme species with a weak field ligand, such as water, in the axial position. Being one of the very few high-spin heme proteins analyzed in this fashion, the resting state CcP expands our knowledge of the heme coordination chemistry in biological systems.

Spin Physics at COMPASS

International Nuclear Information System (INIS)

Schill, Christian

2012-01-01

The COMPASS experiment is a fixed target experiment at the CERN SPS using muon and hadron beams for the investigation of the spin structure of the nucleon and hadron spectroscopy. The main objective of the muon physics program is the study of the spin of the nucleon in terms of its constituents, quarks and gluons. COMPASS has accumulated data during 6 years scattering polarized muons off longitudinally or transversely polarized deuteron ( 6 LiD) or proton (NH 3 ) targets. Results for the gluon polarization are obtained from longitudinal double spin cross section asymmetries using two different channels, open charm production and high transverse momentum hadron pairs, both proceeding through the photon-gluon fusion process. Also, the longitudinal spin structure functions of the proton and the deuteron were measured in parallel as well as the helicity distributions for the three lightest quark flavours. With a transversely polarized target, results were obtained with proton and deuteron targets for the Collins and Sivers asymmetries for charged hadrons as well as for identified kaons and pions. The Collins asymmetry is sensitive to the transverse spin structure of the nucleon, while the Sivers asymmetry reflects correlations between the quark transverse momentum and the nucleon spin. Recently, a new proposal for the COMPASS II experiment was accepted by the CERN SPS which includes two new topics: Exclusive reactions like DVCS and DVMP using the muon beam and a hydrogen target to study generalized parton distributions and Drell-Yan measurements using a pion beam and a polarized NH 3 target to study transverse momentum dependent distributions.

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

Science.gov (United States)

Na, Xieyu; Poirier, M.

2016-07-01

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

Large-amplitude superexchange of high-spin fermions in optical lattices

International Nuclear Information System (INIS)

Jürgensen, Ole; Heinze, Jannes; Lühmann, Dirk-Sören

2013-01-01

We show that fermionic high-spin systems with spin-changing collisions allow one to monitor superexchange processes in optical superlattices with large amplitudes and strong spin fluctuations. By investigating the non-equilibrium dynamics, we find a superexchange dominated regime at weak interactions. The underlying mechanism is driven by an emerging tunneling-energy gap in shallow few-well potentials. As a consequence, the interaction-energy gap that is expected to occur only for strong interactions in deep lattices is re-established. By tuning the optical lattice depth, a crossover between two regimes with negligible particle number fluctuations is found: firstly, the common regime with vanishing spin-fluctuations in deep lattices and, secondly, a novel regime with strong spin fluctuations in shallow lattices. We discuss the possible experimental realization with ultracold 40 K atoms and observable quantities in double wells and two-dimensional plaquettes. (paper)

Role of spin mixing conductance in spin pumping: Enhancement of spin pumping efficiency in Ta/Cu/Py structures

Energy Technology Data Exchange (ETDEWEB)

Deorani, Praveen; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore (Singapore)

2013-12-02

From spin pumping measurements in Ta/Py devices for different thicknesses of Ta, we determine the spin Hall angle to be 0.021–0.033 and spin diffusion length to be 8 nm in Ta. We have also studied the effect of changing the properties of non-magnet/ferromagnet interface by adding a Cu interlayer. The experimental results show that the effective spin mixing conductance increases in the presence of Cu interlayer for Ta/Cu/Py devices whereas it decreases in Pt/Cu/Py devices. Our findings allow the tunability of the spin pumping efficiency by adding a thin interlayer at the non-magnet/ferromagnet interface.

High-fidelity state transfer over an unmodulated linear XY spin chain

International Nuclear Information System (INIS)

Bishop, C. Allen; Ou Yongcheng; Byrd, Mark S.; Wang Zhaoming

2010-01-01

We provide a class of initial encodings that can be sent with a high fidelity over an unmodulated, linear, XY spin chain. As an example, an average fidelity of 96% can be obtained using an 11-spin encoding to transmit a state over a chain containing 10 000 spins. An analysis of the magnetic-field dependence is given, and conditions for field optimization are provided.

A next-to-leading order QCD analysis of the spin structure function $g_1$

CERN Document Server

AUTHOR|(CDS)2067425; Arik, E; Badelek, B; Bardin, G; Baum, G; Berglund, P; Betev, L; Birsa, R; De Botton, N R; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Eichblatt, S; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garzón, J A; Gilly, H; Giorgi, M A; von Goeler, E; Görtz, S; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kiselev, Yu F; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kukhtin, V V; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Litmaath, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Pereira, H; Perrot-Kunne, F; Peshekhonov, V D; Piegia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Puntaferro, R; Rädel, G; Rijllart, A; Reicherz, G; Roberts, J; Rodríguez, M; Rondio, Ewa; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schiller, A; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Tessarotto, F; Thers, D; Tlaczala, W; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Ylöstalo, J; Zanetti, A M; Zaremba, K; Zhao, J

1998-01-01

We present a next-to-leading order QCD analysis of the presently available data on the spin structure function $g_1$ including the final data from the Spin Muon Collaboration (SMC). We present resu lts for the first moments of the proton, deuteron and neutron structure functions, and determine singlet and non-singlet parton distributions in two factorization schemes. We also test the Bjor ken sum rule and find agreement with the theoretical prediction at the level of 10\\%.

Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

DEFF Research Database (Denmark)

Wolber, J.; Ellner, F.; Fridlund, B.

2004-01-01

A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2K, and at a field of 3.354T, corresponding to an electron spin resonance frequency of 94GHz. Trityl radicals are used to directly polarize 13C...... and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use...

Proposal to measure spin-structure functions and semi-exclusive asymmetries for the proton and neutron at HERA

International Nuclear Information System (INIS)

Jackson, H.E.; Hansen, J.O.; Jones, C.E.

1995-01-01

Nucleon spin physics will be studied in the HERMES experiment, that will use polarized internal targets of essentially pure atomic H, D, and 3 He in the HERA electron storage ring at DESY. A series of measurements of spin-dependent properties of the nucleon and few-body nuclei will be made; the spin structure function g 1 (x) of the proton and neutron will be measured to test the Bjorken sum rule and study the fraction of the nucleon spin carried by quarks; the spin structure function g 2 W, sensitive to quark-gluon correlations, and the structure functions b 1 (x), and Δ(x), sensitive to nuclear binding effects, will be measured; and, using the particle identification capability of the HERMES detector, pions will be detected in coincidence with the scattered electrons. The coincident hadron measurements represent the most important extension that can be made at this time to the existing measurements on the nucleon spin structure functions because they provide information about the flavor-dependence of the quark spin distribution in the nucleon. Argonne is providing the Cerenkov counter to be used for particle identification and developing the drifilm coating technique for the ultrathin target cell required for this experiment. The HERMES collaboration intends to use polarized targets with the highest available figures of merit, and the Argonne laser-driven source offers the most promise for a significant advance in present-day targets

High-resolution magnetic resonance spectroscopy using a solid-state spin sensor

Science.gov (United States)

Glenn, David R.; Bucher, Dominik B.; Lee, Junghyun; Lukin, Mikhail D.; Park, Hongkun; Walsworth, Ronald L.

2018-03-01

Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen–vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples, with sensitivity sufficient to detect the magnetic field produced by a single protein. However, the best reported spectral resolution for NMR of molecules using nitrogen–vacancy centres is about 100 hertz. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency). Conventional, inductively detected NMR can provide the necessary high spectral resolution, but its limited sensitivity typically requires millimetre-scale samples, precluding applications that involve smaller samples, such as picolitre-volume chemical analysis or correlated optical and NMR microscopy. Here we demonstrate a measurement technique that uses a solid-state spin sensor (a magnetometer) consisting of an ensemble of nitrogen–vacancy centres in combination with a narrowband synchronized readout protocol to obtain NMR spectral resolution of about one hertz. We use this technique to observe NMR scalar couplings in a micrometre-scale sample volume of approximately ten picolitres. We also use the ensemble of nitrogen–vacancy centres to apply NMR to thermally polarized nuclear spins and resolve chemical-shift spectra from small molecules. Our technique enables analytical NMR spectroscopy at the scale of single cells.

High spin-polarization in ultrathin Co{sub 2}MnSi/CoPd multilayers

Energy Technology Data Exchange (ETDEWEB)

Galanakis, I., E-mail: galanakis@upatras.gr

2015-03-01

Half-metallic Co{sub 2}MnSi 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 Co{sub 2}MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co{sub 2}MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co{sub 2}MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices.

Elimination of Power Divergences in Consistent Model for Spinless and High-Spin Particle Interactions

International Nuclear Information System (INIS)

Kulish, Yu.V.; Rybachuk, E.V.

2007-01-01

The currents for the interaction of the massive high-spin boson (J≥1) with two spinless particles are derived. These currents obey the theorem on currents and fields as well as the theorem on current asymptotics. In one-loop approximation the contributions of high-spin boson to the self-energy operator for a spinless particle are calculated. It is shown that in one loop approximation the high-spin boson contributions for any spin J and mass lead to finite self-energy operators of spinless-particle

A Determination of the Neutron Spin Structure Function

Energy Technology Data Exchange (ETDEWEB)

Hughes, Emlyn W

2003-08-18

The authors report the results of the experiment E142 which measured the spin dependent structure function of the neutron, g{sub 1}{sup n}(x, Q{sup 2}). The experiment was carried out at the Stanford Linear Accelerator Center by measuring an asymmetry in the deep inelastic scattering of polarized electrons from a polarized {sup 3}He target, at electron energies from 19 to 26 GeV. The structure function was determined over the kinematic range 0.03 < BJorken x < 0.6 and 1.0 < Q{sup 2} < 5.5 (GeV/c){sup 2}. An evaluation of the integral {integral}{sub 0}{sup 1} g{sub 1}{sup n}(x,Q{sup 2})dx at fixed Q{sup 2} = 2 (GeV/c){sup 2} yields the final result {Lambda}{sub 1}{sup n} = -0.032 {+-} 0.006 (stat.) {+-} 0.009 (syst.). This result, when combined with the integral of the proton spin structure function measured in other experiments, confirms the fundamental Bjorken sum rule with O({alpha}{sub s}{sup 3}) corrections to within one standard deviation. This is a major success for perturbative Quantum Chromodynamics. Some ancillary results include the findings that the Ellis-Jaffe sum rule for the neutron is violated at the 2 {sigma} level, and that the total contribution of the quarks to the helicity of the nucleon is 0.36 {+-} 0.10. The strange sea polarization is estimated to be small and negative, {Delta}s = -0.07 {+-} 0.04.

Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

Energy Technology Data Exchange (ETDEWEB)

Artzi, Yaron; Twig, Ygal; Blank, Aharon [Schulich Faculty of Chemistry Technion—Israel Institute of Technology, Haifa 32000 (Israel)

2015-02-23

Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ∼34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

Quantum spin liquids in the absence of spin-rotation symmetry: Application to herbertsmithite

Science.gov (United States)

Dodds, Tyler; Bhattacharjee, Subhro; Kim, Yong Baek

2013-12-01

It has been suggested that the nearest-neighbor antiferromagnetic Heisenberg model on the Kagome lattice may be a good starting point for understanding the spin-liquid behavior discovered in herbertsmithite. In this work, we investigate possible quantum spin liquid phases in the presence of spin-rotation symmetry-breaking perturbations such as Dzyaloshinskii-Moriya and Ising interactions, as well as second-neighbor antiferromagnetic Heisenberg interactions. Experiments suggest that such perturbations are likely to be present in herbertsmithite. We use the projective symmetry group analysis within the framework of the slave-fermion construction of quantum spin liquid phases and systematically classify possible spin liquid phases in the presence of perturbations mentioned above. The dynamical spin-structure factor for relevant spin liquid phases is computed and the effect of those perturbations are studied. Our calculations reveal dispersive features in the spin structure factor embedded in a generally diffuse background due to the existence of fractionalized spin-1/2 excitations called spinons. For two of the previously proposed Z2 states, the dispersive features are almost absent, and diffuse scattering dominates over a large energy window throughout the Brillouin zone. This resembles the structure factor observed in recent inelastic neutron-scattering experiments on singlet crystals of herbertsmithite. Furthermore, one of the Z2 states with the spin structure factor with mostly diffuse scattering is gapped, and it may be adiabatically connected to the gapped spin liquid state observed in recent density-matrix renormalization group calculations for the nearest-neighbor antiferromagnetic Heisenberg model. The perturbations mentioned above are found to enhance the diffuse nature of the spin structure factor and reduce the momentum dependencies of the spin gap. We also calculate the electron spin resonance (ESR) absorption spectra that further characterize the role of

FERMILAB: High energy spin effects

Energy Technology Data Exchange (ETDEWEB)

Anon.

1991-03-15

While many physicists would agree that it is important to study interactions of different isospin states (for example comparing proton and neutron data), many of them also accept as normal data averaged or integrated over ordinary spin. However an ongoing programme at Brookhaven studying elastic scattering (where the incoming particles 'bounce' off each other) produced marked spin effects which are not well understood. Our understanding of particle interactions should not be influenced by which observables are easy to measure and which aren't, and until a clear understanding of spin effects emerges, it is important to continue and extend these studies.

High spin states in 143Sm

International Nuclear Information System (INIS)

Raut, R.; Ganguly, S.; Kshetri, R.; Banerjee, P.; Bhattacharya, S.; Dasmahapatra, B.; Mukherjee, A.; Mukherjee, G.; Sarkar, M. Saha; Goswami, A.; Gangopadhyay, G.; Mukhopadhyay, S.; Krishichayan,; Chakraborty, A.; Ghughre, S. S.; Bhattacharjee, T.; Basu, S. K.

2006-01-01

The high spin states of 143 Sm have been studied by in-beam γ-spectroscopy following the reaction 130 Te( 20 Ne,7n) 143 Sm at E lab =137 MeV, using a Clover detector array. More than 50 new gamma transitions have been placed above the previously known J π =23/2 - , 30 ms isomer at 2795 keV. The level scheme of 143 Sm has been extended up to 12 MeV and spin-parity assignments have been made to most of the newly proposed level. Theoretical calculation with the relativistic mean field approach using blocked BCS method, has been performed. A sequence of levels connected by M1 transitions have been observed at an excitation energy ∼8.6 MeV. The sequence appears to be a magnetic rotational band from systematics

Electronic heat, charge and spin transport in superconductor-ferromagnetic insulator structures

Energy Technology Data Exchange (ETDEWEB)

Bergeret, Sebastian [Materials Physics Center (CFM-CSIC), San Sebastian (Spain); Donostia International Physics Center (DIPC), San Sebastian (Spain)

2015-07-01

It is known for some time that a superconducting (S) film in contact with a ferromagnetic insulator (FI) exhibits a spin-splitting in the density of states (DoS). Recently we have explored different S-FI hybrid structures and predicted novel effects exploiting such spin-splitting of the DoS. In this talk I will briefly discuss (i) a heat valve based on a FI-S-I-S-FI Josephson junction; (ii) a thermoelectric transistor and (iii) the occurrence of a giant thermophase in a thermally-biased Josephson junction.

High spin states in 63Cu. 17/2+ isomeric yrast state

International Nuclear Information System (INIS)

Tsan Ung Chan; Bruandet, J.F.; Dauchy, A.; Giorni, A.; Glasser, F.; Morand, C.; Chambon, B.; Drain, D.

1979-01-01

The 63 Cu nucleus has been studied via the reaction 61 Ni(α, pnγ), using different in beam γ spectroscopy techniques. An isomeric high-spin Yrast state 17/2 + (tau = 6.1 +- 0.6ns) is located at 4498 keV. The gsub(9/2) shell must be involved to explain positive high-spin states established in this work [fr

Spin structures on algebraic curves and their applications in string theories

International Nuclear Information System (INIS)

Ferrari, F.

1990-01-01

The free fields on a Riemann surface carrying spin structures live on an unramified r-covering of the surface itself. When the surface is represented as an algebraic curve related to the vanishing of the Weierstrass polynomial, its r-coverings are algebraic curves as well. We construct explicitly the Weierstrass polynomial associated to the r-coverings of an algebraic curve. Using standard techniques of algebraic geometry it is then possible to solve the inverse Jacobi problem for the odd spin structures. As an application we derive the partition functions of bosonic string theories in many examples, including two general curves of genus three and four. The partition functions are explicitly expressed in terms of branch points apart from a factor which is essentially a theta constant. 53 refs., 4 figs. (Author)

Andreev spectrum with high spin-orbit interactions: Revealing spin splitting and topologically protected crossings

Science.gov (United States)

Murani, A.; Chepelianskii, A.; Guéron, S.; Bouchiat, H.

2017-10-01

In order to point out experimentally accessible signatures of spin-orbit interaction, we investigate numerically the Andreev spectrum of a multichannel mesoscopic quantum wire (N) with high spin-orbit interaction coupled to superconducting electrodes (S), contrasting topological and nontopological behaviors. In the nontopological case (square lattice with Rashba interactions), we find that the Kramers degeneracy of Andreev levels is lifted by a phase difference between the S reservoirs except at multiples of π , when the normal quantum wires can host several conduction channels. The level crossings at these points invariant by time-reversal symmetry are not lifted by disorder. Whereas the dc Josephson current is insensitive to these level crossings, the high-frequency admittance (susceptibility) at finite temperature reveals these level crossings and the lifting of their degeneracy at π by a small Zeeman field. We have also investigated the hexagonal lattice with intrinsic spin-orbit interaction in the range of parameters where it is a two-dimensional topological insulator with one-dimensional helical edges protected against disorder. Nontopological superconducting contacts can induce topological superconductivity in this system characterized by zero-energy level crossing of Andreev levels. Both Josephson current and finite-frequency admittance carry then very specific signatures at low temperature of this disorder-protected Andreev level crossing at π and zero energy.

Anomalous magnetic structure and spin dynamics in magnetoelectric LiFePO₄

DEFF Research Database (Denmark)

Toft-Petersen, Rasmus; Reehuis, Manfred; Jensen, Thomas Bagger Stibius

2015-01-01

We report significant details of the magnetic structure and spin dynamics of LiFePO4 obtained by single-crystal neutron scattering. Our results confirm a previously reported collinear rotation of the spins away from the principal b axis, and they determine that the rotation is toward the a axis...

Nucleon spin structure functions

International Nuclear Information System (INIS)

Close, F.E.

1989-01-01

There has been recent excitement arising from the claim by the EMC collaboration that none of the proton's spin is carried by quarks. There are many textbooks, including those written by some members of this audience which assert that the proton's spin is carried by quarks. I will review the history of deep inelastic scattering of polarized leptons from polarized protons, culminating in this most recent dramatic claim. I will show that, for the last decade, data have appeared consistent with predictions of the quark model and highlight what the new and potentially exciting data are. I will conclude with suggestions for the future, and discuss the polarization dependence of inclusive hadron production. 35 refs

Structure and dynamics of spin-labeled insulin entrapped in a silica matrix by the sol-gel method.

Science.gov (United States)

Vanea, E; Gruian, C; Rickert, C; Steinhoff, H-J; Simon, V

2013-08-12

The structure and conformational dynamics of insulin entrapped into a silica matrix was monitored during the sol to maturated-gel transition by electron paramagnetic resonance (EPR) spectroscopy. Insulin was successfully spin-labeled with iodoacetamide and the bifunctional nitroxide reagent HO-1944. Room temperature continuous wave (cw) EPR spectra of insulin were recorded to assess the mobility of the attached spin labels. Insulin conformation and its distribution within the silica matrix were studied using double electron-electron resonance (DEER) and low-temperature cw-EPR. A porous oxide matrix seems to form around insulin molecules with pore diameters in the order of a few nanometers. Secondary structure of the encapsulated insulin investigated by Fourier transform infrared spectroscopy proved a high structural integrity of insulin even in the dried silica matrix. The results show that silica encapsulation can be used as a powerful tool to effectively isolate and functionally preserve biomolecules during preparation, storage, and release.

The Crystal Structure of a High-Spin Oxoiron(IV) Complex and Characterization of Its Self-Decay Pathway

Energy Technology Data Exchange (ETDEWEB)

England, J.; Guo, Y; Farquhar, E; Young, Jr., V; Münck, E; Que, Jr., L

2010-01-01

[Fe{sup IV}(O)(TMG{sub 3}tren)]{sup 2+} (1; TMG{sub 3}tren = 1,1,1-tris{l_brace}2-[N{sup 2}-(1,1,3,3-tetramethylguanidino)]ethyl{r_brace}amine) is a unique example of an isolable synthetic S = 2 oxoiron(IV) complex, which serves as a model for the high-valent oxoiron(IV) intermediates observed in nonheme iron enzymes. Congruent with DFT calculations predicting a more reactive S = 2 oxoiron(IV) center, 1 has a lifetime significantly shorter than those of related S = 1 oxoiron(IV) complexes. The self-decay of 1 exhibits strictly first-order kinetic behavior and is unaffected by solvent deuteration, suggesting an intramolecular process. This hypothesis was supported by ESI-MS analysis of the iron products and a significant retardation of self-decay upon use of a perdeuteromethyl TMG{sub 3}tren isotopomer, d{sub 36}-1 (KIE = 24 at 25 C). The greatly enhanced thermal stability of d{sub 36}-1 allowed growth of diffraction quality crystals for which a high-resolution crystal structure was obtained. This structure showed an Fe=O unit (r = 1.661(2) {angstrom}) in the intended trigonal bipyramidal geometry enforced by the sterically bulky tetramethylguanidinyl donors of the tetradentate tripodal TMG{sub 3}tren ligand. The close proximity of the methyl substituents to the oxoiron unit yielded three symmetrically oriented short C-D {hor_ellipsis} O nonbonded contacts (2.38-2.49 {angstrom}), an arrangement that facilitated self-decay by rate-determining intramolecular hydrogen atom abstraction and subsequent formation of a ligand-hydroxylated iron(III) product. EPR and Moessbauer quantification of the various iron products, referenced against those obtained from reaction of 1 with 1,4-cyclohexadiene, allowed formulation of a detailed mechanism for the self-decay process. The solution of this first crystal structure of a high-spin (S = 2) oxoiron(IV) center represents a fundamental step on the path toward a full understanding of these pivotal biological intermediates.

Magnetic structure of the spin valve interface

International Nuclear Information System (INIS)

Nicholson, D.M.C.; Butler, W.H.; Zhang, X.; MacLaren, J.M.; Gurney, B.A.; Speriosu, V.S.

1994-01-01

Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR

Spin spring behavior in exchange coupled soft and high-coercivity hard ferromagnets.

Energy Technology Data Exchange (ETDEWEB)

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.

Sequence- and structure-dependent DNA base dynamics: Synthesis, structure, and dynamics of site and sequence specifically spin-labeled DNA

International Nuclear Information System (INIS)

Spaltenstein, A.; Robinson, B.H.; Hopkins, P.B.

1989-01-01

A nitroxide spin-labeled analogue of thymidine (1a), in which the methyl group is replaced by an acetylene-tethered nitroxide, was evaluated as a probe for structural and dynamics studies of sequence specifically spin-labeled DNA. Residue 1a was incorporated into synthetic deoxyoligonucleotides by using automated phosphite triester methods. 1 H NMR, CD, and thermal denaturation studies indicate that 1a (T) does not significantly alter the structure of 5'-d(CGCGAATT*CGCG) from that of the native dodecamer. EPR studies on monomer, single-stranded, and duplexed DNA show that 1a readily distinguishes environments of different rigidity. Comparison of the general line-shape features of the observed EPR spectra of several small duplexes (12-mer, 24-mer) with simulated EPR spectra assuming isotropic motion suggests that probe 1a monitors global tumbling of small duplexes. Increasing the length of the DNA oligomers results in significant deviation from isotropic motion, with line-shape features similar to those of calculated spectra of objects with isotropic rotational correlation times of 20-100 ns. EPR spectra of a spin-labeled GT mismatch and a T bulge in long DNAs are distinct from those of spin-labeled Watson-Crick paired DNAs, further demonstrating the value of EPR as a tool in the evaluation of local dynamic and structural features in macromolecules

The E142 SLAC experiment: measurement of the neutron gn1(x) spin structure function

International Nuclear Information System (INIS)

Roblin, Y.

1995-01-01

This thesis describes the E142 experiment which has been carried out at the Stanford Linear Accelerator (SLAC), USA, from October to December 1992. This experiment of polarized inelastic scattering of a 22.6 GeV electron beam on a polarized helium 3 target has allowed the first measurement of the neutron g n 1 (x) spin structure function. The knowledge of this structure function gives informations on the nucleon spin structure. On the other hand, the g n 1 (x) structure function integral value on the 0 2 mean value of 2 GeV 2 after some extrapolations. This value is at about two standard deviations away from the theoretical predictions of the Ellis-Jaffe rule. Thanks to the existing experimental results for the proton (E143 experiment), the Bjorken sum rule has been precisely tested and is perfectly compatible with the theoretical value. The results have allowed to estimate the nucleon spin fraction carried by the quarks. (J.S.). 86 refs., 58 figs., 13 tabs

Structure of high spin states of 76Kr and 78Kr nuclei

Indian Academy of Sciences (India)

Evolution of the shape with spin, and rotation alignment of proton as well as neutron ... by studying ground state properties of 76,78Kr by employing two sets of basis .... Figure 3. Energies of the yrast states of 76,78Kr nuclei compared with the.

Vortex Flipping in Superconductor-Ferromagnet Spin Valve Structures

Science.gov (United States)

Patino, Edgar J.; Aprili, Marco; Blamire, Mark; Maeno, Yoshiteru

2014-03-01

We report in plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni, below the superconducting transition Tc, our results show strong evidence of vortex flipping driven by the ferromagnets magnetization. This is a direct consequence of proximity effect that leads to vortex supercurrents leakage into the ferromagnets. Here the polarized electron spins are subject to vortices magnetic field occasioning vortex flipping. Such novel mechanism has been made possible for the first time by fabrication of the F/S/F/AF multilayered spin valves with a thin-enough S layer to barely confine vortices inside as well as thin-enough F layers to align and control the magnetization within the plane. When Co is used there is no observation of vortex flipping effect. This is attributed to Co shorter coherence length. Interestingly instead a reduction in pinning field of about 400 Oe is observed when the Nb layer is in superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts any explanation must be directly related to proximity effect and thus a remarkable phenomenon that deserves further investigation. Programa Nacional de Ciencias Basicas COLCIENCIAS (No. 120452128168).

Structural and electronic properties of Er-monopnictides under high pressure

Energy Technology Data Exchange (ETDEWEB)

Pandit, Premlata, E-mail: lataprem29@gmail.co [Department of Physics, Barkatullah University, Bhopal, Madhya Pradesh 462026 (India); Srivastava, Vipul [Department of Physics, Oriental Institute of Science and Technology, Thakral Nagar, Bhopal (India); Rajagopalan, M. [Crystal Growth Centre, Anna University, Chennai 600 025 (India); Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, Madhya Pradesh 462026 (India)

2010-05-01

We present the results of theoretical calculations on the structural, magnetic and electronic properties of Er-monopnictides using self-consistent first principles tight-binding linear-muffin-tin-orbital (TB-LMTO) method within the atomic-sphere approximation (ASA). Both spin-polarized and non-spin-polarized calculations are performed to check the magnetic stability of these compounds. We find that ErN, ErP and ErAs are metallic in ferromagnetic (FM) phase in both the spin channels and stable in NaCl-type (B{sub 1}) structure at ambient pressure. We predict NaCl-type (B{sub 1}) to CsCl-type (B{sub 2}) structural phase transition in ErN, ErP and ErAs at pressures of 146.1, 60.2 and 53.2 GPa, respectively and remain metallic ferromagnetic at high pressure. We calculate equilibrium lattice constants (a), bulk modulus (B), magnetic moments (mu{sub B}) and electronic properties of these compounds in B{sub 1} and B{sub 2} phases and compare with available experimental and theoretical results.

Coherent manipulation of spin correlations in the Hubbard model

Science.gov (United States)

Wurz, N.; Chan, C. F.; Gall, M.; Drewes, J. H.; Cocchi, E.; Miller, L. A.; Pertot, D.; Brennecke, F.; Köhl, M.

2018-05-01

We coherently manipulate spin correlations in a two-component atomic Fermi gas loaded into an optical lattice using spatially and time-resolved Ramsey spectroscopy combined with high-resolution in situ imaging. This technique allows us not only to imprint spin patterns but also to probe the static magnetic structure factor at an arbitrary wave vector, in particular, the staggered structure factor. From a measurement along the diagonal of the first Brillouin zone of the optical lattice, we determine the magnetic correlation length and the individual spatial spin correlators. At half filling, the staggered magnetic structure factor serves as a sensitive thermometer, which we employ to study the equilibration in the spin and density sector during a slow quench of the lattice depth.

Investigations on the local structure and the spin-Hamiltonian ...

Indian Academy of Sciences (India)

2016-07-13

Jul 13, 2016 ... (2016) 87: 22 c Indian Academy of Sciences. DOI 10.1007/s12043-016-1234-6. Investigations on the local structure and the spin-Hamiltonian parameters for the tetragonal Cu. 2+ centre in ZnGeF6·6H2O crystal. LI CHAO-YING. ∗. , HUANG YING and ZHENG XUE MEI. School of Physics and Electronic ...

High-mobility ultrathin semiconducting films prepared by spin coating

Science.gov (United States)

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).

Self-sustained spin-polarized current oscillations in multiquantum well structures

Energy Technology Data Exchange (ETDEWEB)

Escobedo, Ramon [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, Manuel; Bonilla, Luis L [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Platero, Gloria [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco (Spain)], E-mail: escobedo@unican.es, E-mail: manuel.carretero@uc3m.es, E-mail: bonilla@ing.uc3m.es, E-mail: gplatero@icmm.csic.es

2009-01-15

Nonlinear transport through diluted magnetic semiconductor nanostructures is investigated. We have considered a II-VI multiquantum well nanostructure whose wells are selectively doped with Mn. The response to a dc voltage bias may be either a stationary or an oscillatory current. We have studied the transition from stationary to time-dependent current as a function of the doping density and the number of quantum wells. Analysis and numerical solution of a nonlinear spin transport model shows that the current in a structure without magnetic impurities is stationary, whereas current oscillations may appear if at least one well contains magnetic impurities. For long structures having two wells with magnetic impurities, a detailed analysis of nucleation of charge dipole domains shows that self-sustained current oscillations are caused by repeated triggering of dipole domains at the magnetic wells and motion towards the collector. Depending on the location of the magnetic wells and the voltage, dipole domains may be triggered at both wells or at only one. In the latter case, the well closer to the collector may inhibit domain motion between the first and the second well inside the structure. Our study could allow design of oscillatory spin-polarized current injectors.

Dynamic nuclear spin polarization

Energy Technology Data Exchange (ETDEWEB)

Stuhrmann, H B [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

1996-11-01

Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

Microscopic approach of the spectral property of 1+ and high-spin states in 124Te nucleus

International Nuclear Information System (INIS)

Shi Zhuyi; Ni Shaoyong; Tong Hong; Zhao Xingzhi

2004-01-01

Using a microscopic sdIBM-2+2q·p· approach, the spectra of the low-spin and partial high-spin states in 124 Te nucleus are relatively successfully calculated. In particular, the 1 1 + , 1 2 + , 3 1 + , 3 2 + and 5 1 + states are successfully reproduced, the energy relationship resulting from this approach identifies that the 6 1 + , 8 1 + and 10 1 + states belong to the aligned states of the two protons. This can explain the recent experimental results that the collective structures may coexist with the single-particle states. So this approach becomes a powerful tool for successfully describing the spectra of general nuclei without clear symmetry and of isotopes located at transitional regions. Finally, the aligned-state structure and the broken-pair energy of the two-quasi-particle are discussed

Spin physics in the high energy hadron productions. A systematic study of the spin asymmetries induced by pp, γp, ep and νp collisions

International Nuclear Information System (INIS)

Kubo, K.-I.; Suzuki, K.; Nakajima, N.

2002-01-01

The spin polarizations of hadrons inclusively produced by pp, γp and νp collisions are studied by the quark rearrangement model. The present model is a phenomenological one based on the relativistic spin equations of motion and using the quark distribution functions in hadrons and photon. A general success of the model is demonstrated. We find usefulness of the present formulation for studying the dynamics producing spin asymmetry distributions and the statics determining signs and magnitudes of the spin polarization by reflecting the characteristic quark structure in hadrons. (author)

Spin-orbit-induced spin splittings in polar transition metal dichalcogenide monolayers

KAUST Repository

Cheng, Yingchun; Zhu, Zhiyong; Tahir, Muhammad; Schwingenschlö gl, Udo

2013-01-01

. We present ab initio electronic structure, phonon, and molecular-dynamics calculations to study the structural stability and spin-orbit-induced spin splitting in the transition metal dichalcogenide monolayers MXY (M = Mo, W and X, Y = S, Se, Te

Bimodule structure in the periodic gℓ(1|1) spin chain

International Nuclear Information System (INIS)

Gainutdinov, A.M.; Read, N.; Saleur, H.

2013-01-01

This paper is the second in a series devoted to the study of periodic super-spin chains. In our first paper (Gainutdinov et al., 2013 [3]), we have studied the symmetry algebra of the periodic gℓ(1|1) spin chain. In technical terms, this spin chain is built out of the alternating product of the gℓ(1|1) fundamental representation and its dual. The local energy densities — the nearest neighbour Heisenberg-like couplings — provide a representation of the Jones–Temperley–Lieb (JTL) algebra JTL N . The symmetry algebra is then the centralizer of JTL N , and turns out to be smaller than for the open chain, since it is now only a subalgebra of U q sℓ(2) at q=i — dubbed U q odd sℓ(2) in Gainutdinov et al. (2013) [3]. A crucial step in our associative algebraic approach to bulk logarithmic conformal field theory (LCFT) is then the analysis of the spin chain as a bimodule over U q odd sℓ(2) and JTL N . While our ultimate goal is to use this bimodule to deduce properties of the LCFT in the continuum limit, its derivation is sufficiently involved to be the sole subject of this paper. We describe representation theory of the centralizer and then use it to find a decomposition of the periodic gℓ(1|1) spin chain over JTL N for any even N and ultimately a corresponding bimodule structure. Applications of our results to the analysis of the bulk LCFT will then be discussed in the third part of this series

Research on the development of the centrifugal spinning

Directory of Open Access Journals (Sweden)

Zhang Zhiming

2017-01-01

Full Text Available Centrifugal spinning is a new and efficient method to produce nanofibers quickly. It makes use of the centrifugal force instead of high voltage to produce the nanofibers. The centrifugal spinning has many advantages such as no high voltage, high yield, simple structure, no pollution and can be applied to high polymer material, ceramic and metal material. In order to have more understand about this novel nanofibers formation method, this paper introduces the method of centrifugal spinning and the effect of rotation speed, the properties of material such as viscosity and solvent evaporation, collector distance which have an impact on nanofibers morphology and diameter were also analyzed.

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

Science.gov (United States)

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.

High temperature resistant nanofiber by bubbfil-spinning

Directory of Open Access Journals (Sweden)

Li Ya

2015-01-01

Full Text Available Heat-resisting nanofibers have many potential applications in various industries, and the bubbfil spinning is the best candidate for mass-production of such materials. Polyether sulfone/zirconia solution with a bi-solvent system is used in the experiment. Experimental result reveals that polyether sulfone/zirconia nanofibers have higher resistance to high temperature than pure polyether sulfone fibers, and can be used as high-temperature-resistant filtration materials.

Demonstrating multibit magnetic memory in the Fe8 high-spin molecule by muon spin rotation

Science.gov (United States)

Shafir, Oren; Keren, Amit; Maegawa, Satoru; Ueda, Miki; Amato, Alex; Baines, Chris

2005-09-01

We develop a method to detect the quantum nature of high-spin molecules using muon spin rotation and a three-step field cycle ending always with the same field. We use this method to demonstrate that the Fe8 molecule can remember six (possibly eight) different histories (bits). A wide range of fields can be used to write a particular bit, and the information is stored in discrete states. Therefore, Fe8 can be used as a model compound for multibit magnetic memory. Our experiment also paves the way for magnetic quantum tunneling detection in films.

High precision pulsar timing and spin frequency second derivatives

Science.gov (United States)

Liu, X. J.; Bassa, C. G.; Stappers, B. W.

2018-05-01

We investigate the impact of intrinsic, kinematic and gravitational effects on high precision pulsar timing. We present an analytical derivation and a numerical computation of the impact of these effects on the first and second derivative of the pulsar spin frequency. In addition, in the presence of white noise, we derive an expression to determine the expected measurement uncertainty of a second derivative of the spin frequency for a given timing precision, observing cadence and timing baseline and find that it strongly depends on the latter (∝t-7/2). We show that for pulsars with significant proper motion, the spin frequency second derivative is dominated by a term dependent on the radial velocity of the pulsar. Considering the data sets from three Pulsar Timing Arrays, we find that for PSR J0437-4715 a detectable spin frequency second derivative will be present if the absolute value of the radial velocity exceeds 33 km s-1. Similarly, at the current timing precision and cadence, continued timing observations of PSR J1909-3744 for about another eleven years, will allow the measurement of its frequency second derivative and determine the radial velocity with an accuracy better than 14 km s-1. With the ever increasing timing precision and observing baselines, the impact of the, largely unknown, radial velocities of pulsars on high precision pulsar timing can not be neglected.

High field electron-spin transport and observation of the Dyakonov-Perel spin relaxation of drifting electrons in low temperature-grown gallium arsenide

International Nuclear Information System (INIS)

Miah, M. Idrish

2008-01-01

High field electron-spin transport in low temperature-grown gallium arsenide is studied. We generate electron spins in the samples by optical pumping. During transport, we observe the Dyakonov-Perel (DP) [M.I. Dyakonov, V.I. Perel, Zh. Eksp. Teor. Fiz. 60 (1971) 1954] spin relaxation of the drifting electrons. The results are discussed and are compared with those obtained in calculations of the DP spin relaxation frequency of the hot electrons. A good agreement is obtained

High field electron-spin transport and observation of the Dyakonov-Perel spin relaxation of drifting electrons in low temperature-grown gallium arsenide

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong-4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

2008-11-17

High field electron-spin transport in low temperature-grown gallium arsenide is studied. We generate electron spins in the samples by optical pumping. During transport, we observe the Dyakonov-Perel (DP) [M.I. Dyakonov, V.I. Perel, Zh. Eksp. Teor. Fiz. 60 (1971) 1954] spin relaxation of the drifting electrons. The results are discussed and are compared with those obtained in calculations of the DP spin relaxation frequency of the hot electrons. A good agreement is obtained.

The magnetic structure on the ground state of the equilateral triangular spin tube

International Nuclear Information System (INIS)

Matsui, Kazuki; Goto, Takayuki; Manaka, Hirotaka; Miura, Yoko

2016-01-01

The ground state of the frustrated equilateral triangular spin tube CsCrF_4 is still hidden behind a veil though NMR spectrum broaden into 2 T at low temperature. In order to investigate the spin structure in an ordered state by "1"9F-NMR, we have determined the anisotropic hyperfine coupling tensors for each three fluorine sites in the paramagnetic state. The measurement field was raised up to 10 T to achieve highest resolution. The preliminary analysis using the obtained hyperfine tensors has shown that the archetypal 120°-type structure in ab-plane does not accord with the NMR spectra of ordered state.

Study of the spin structure functions of the nucleon: the E143 experiment at SLAC

International Nuclear Information System (INIS)

Grenier, Philippe

1995-01-01

In this thesis, we present the results of the E143 experiment of deep inelastic scattering of 29 GeV polarized electrons from polarized NH 3 and ND 3 targets, at SLAC. The goal of the experiment is the measurement of the spin structure functions g 1 and g 2 of the nucleon which provide information on its internal spin structure. Experimentally, the structure functions are extracted from the measurement of cross section asymmetries. Our measured values of the first moment of g 1 are two and three standard deviations below the Ellis-Jaffe sum rule predictions, for the proton and for the deuteron, respectively. The Bjoerken sum rule, a QCD fundamental prediction, has been confirmed. We find the quark contribution to the nucleon spin to be around 30 pc. Our results on g 2 are well described by the Wandzura-Wilczek expression. (author) [fr

Investigation of spin-gapless semiconductivity and half-metallicity in Ti2MnAl-based compounds

International Nuclear Information System (INIS)

Lukashev, P.; Staten, B.; Hurley, N.; Kharel, P.; Gilbert, S.; Fuglsby, R.; Huh, Y.; Valloppilly, S.; Zhang, W.; Skomski, R.; Sellmyer, D. J.; Yang, K.

2016-01-01

The increasing interest in spin-based electronics has led to a vigorous search for new materials that can provide a high degree of spin polarization in electron transport. An ideal candidate would act as an insulator for one spin channel and a conductor or semiconductor for the opposite spin channel, corresponding to the respective cases of half-metallicity and spin-gapless semiconductivity. Our first-principle electronic-structure calculations indicate that the metallic Heusler compound Ti 2 MnAl becomes half-metallic and spin-gapless semiconducting if half of the Al atoms are replaced by Sn and In, respectively. These electronic structures are associated with structural transitions from the regular cubic Heusler structure to the inverted cubic Heusler structure.

Spin-orbit excitations and electronic structure of the putative Kitaev magnet $\\alpha$-RuCl$_3$

OpenAIRE

Sandilands, Luke J.; Tian, Yao; Reijnders, Anjan A.; Kim, Heung-Sik; Plumb, Kemp W.; Kee, Hae-Young; Kim, Young-June; Burch, Kenneth S.

2015-01-01

Mott insulators with strong spin-orbit coupling have been proposed to host unconventional magnetic states, including the Kitaev quantum spin liquid. The 4$d$ system $\\alpha$-RuCl$_3$ has recently come into view as a candidate Kitaev system, with evidence for unusual spin excitations in magnetic scattering experiments. We apply a combination of optical spectroscopy and Raman scattering to study the electronic structure of this material. Our measurements reveal a series of orbital excitations i...

High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

Energy Technology Data Exchange (ETDEWEB)

Jungfleisch, Matthias B.; Sklenar, Joseph; Ding, Junjia; Park, Jungsik; Pearson, John E.; Novosad, Valentine; Schiffer, Peter; Hoffmann, Axel

2017-12-01

Spin-torque ferromagnetic resonance arises in heavy metal-ferromagnet heterostructures when an alternating charge current is passed through the bilayer stack. The methodology to detect the resonance is based on the anisotropic magnetoresistance, which is the change in the electrical resistance due to different orientations of the magnetization. In connected networks of ferromagnetic nanowires, known as artificial spin ice, the magnetoresistance is rather complex owing to the underlying collective behavior of the geometrically frustrated magnetic domain structure. Here, we demonstrate spin-torque ferromagnetic resonance investigations in a square artificial spin-ice system and correlate our observations to magneto-transport measurements. The experimental findings are described using a simulation approach that highlights the importance of the correlated dynamics response of the magnetic system. Our results open the possibility of designing reconfigurable microwave oscillators and magnetoresistive devices based on connected networks of nanomagnets.

High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

Science.gov (United States)

Jungfleisch, Matthias B.; Sklenar, Joseph; Ding, Junjia; Park, Jungsik; Pearson, John E.; Novosad, Valentine; Schiffer, Peter; Hoffmann, Axel

2017-12-01

Spin-torque ferromagnetic resonance arises in heavy metal-ferromagnet heterostructures when an alternating charge current is passed through the bilayer stack. The methodology to detect the resonance is based on the anisotropic magnetoresistance, which is the change in the electrical resistance due to different orientations of the magnetization. In connected networks of ferromagnetic nanowires, known as artificial spin ice, the magnetoresistance is rather complex owing to the underlying collective behavior of the geometrically frustrated magnetic domain structure. Here, we demonstrate spin-torque ferromagnetic resonance investigations in a square artificial spin-ice system and correlate our observations to magnetotransport measurements. The experimental findings are described using a simulation approach that highlights the importance of the correlated dynamics response of the magnetic system. Our results open the possibility of designing reconfigurable microwave oscillators and magnetoresistive devices based on connected networks of nanomagnets.

Spin Current Switching and Spin-Filtering Effects in Mn-Doped Boron Nitride Nanoribbons

Directory of Open Access Journals (Sweden)

G. A. Nemnes

2012-01-01

Full Text Available The spin transport properties are investigated by means of the first principle approach for boron nitride nanoribbons with one or two substitutional Mn impurities, connected to graphene electrodes. The spin current polarization is evaluated using the nonequilibrium Green’s function formalism for each structure and bias. The structure with one Mn impurity reveals a transfer characteristics suitable for a spin current switch. In the case of two Mn impurities, the system behaves as an efficient spin-filter device, independent on the ferromagnetic or antiferromagnetic configurations of the magnetic impurities. The experimental availability of the building blocks as well as the magnitudes of the obtained spin current polarizations indicates a strong potential of the analyzed structures for future spintronic devices.

Spin noise spectroscopy of donor-bound electrons in ZnO

Science.gov (United States)

Horn, H.; Balocchi, A.; Marie, X.; Bakin, A.; Waag, A.; Oestreich, M.; Hübner, J.

2013-01-01

We investigate the intrinsic spin dynamics of electrons bound to Al impurities in bulk ZnO by optical spin noise spectroscopy. Spin noise spectroscopy enables us to investigate the longitudinal and transverse spin relaxation time with respect to nuclear and external magnetic fields in a single spectrum. On one hand, the spin dynamic is dominated by the intrinsic hyperfine interaction with the nuclear spins of the naturally occurring 67Zn isotope. We measure a typical spin dephasing time of 23 ns, in agreement with the expected theoretical values. On the other hand, we measure a third, very high spin dephasing rate which is attributed to a high defect density of the investigated ZnO material. Measurements of the spin dynamics under the influence of transverse as well as longitudinal external magnetic fields unambiguously reveal the intriguing connections of the electron spin with its nuclear and structural environment.

Laser - Polarized HE-3 Target Used for a Precision Measurement of the Neutron Spin Structure

Energy Technology Data Exchange (ETDEWEB)

Romalis, M

2003-11-05

This thesis describes a precision measurement of the deep inelastic neutron spin structure function g{sub 1}{sup n}(x). The main motivation for the experiment is a test of the Bjorken sum rule. Because of smaller statistical errors and broader kinematic coverage than in previous experiments, we are able to study in detail the behavior of the spin structure function g{sub 1}{sup n}(x) for low values of the Bjorken scaling variable x. We find that it has a strongly divergent behavior, in contradiction to the naive predictions of the Regge theory. This calls into question the methods commonly used for extrapolation of g{sub 1}{sup n}(x) to x = 0. The difference between the proton and the neutron spin structure functions is less divergent at low x, so a test of the Bjorken sum rule is possible. We confirm the sum rule with an accuracy of 8%. The experiment was performed at SLAC using a 50 GeV polarized electron beam and a polarized {sup 3}He target. In this thesis the polarized target is described in detail. We used the technique of Rb optical pumping and Rb-He spin exchange to polarize the {sup 3}He. Because of a novel mechanical design our target had the smallest dilution ever achieved for a high density gas target. Since this is a precision measurement, particular efforts were made to reduce the systematic errors due to the uncertainty in the target parameters. Most important parameters were measured by more than one method. We implemented novel techniques for measuring the thickness of the glass windows of the target, the {sup 3}He density, and the polarization. In particular, one of the methods for measuring the gas density relied on the broadening of the Rb optical absorption lines by collisions with {sup 3}He atoms. The calibration of this technique resulted in the most precise measurements of the pressure broadening parameters for {sup 3}He as well as several other gases, which are described in an Appendix. The polarization of the {sup 3}He was also measured by

Application of nonlinear EPR and NMR responses on spin systems in structure and relaxation structures

Energy Technology Data Exchange (ETDEWEB)

Polyakov, A I; Ryabikin, Yu A; Bitenbaev, M M [Inst. of Physics and Technology, Almaty (Kazakhstan)

2004-07-01

Full text: In this work results of investigation of paramagnetic systems (irradiated polymers and crystals, plastic-deformed metals, systems with strong exchange interaction, etc.) by methods of nonlinear relaxation spectroscopy (NRS) are presented. The NRS theoretical grounds were developed in the earlier works. Later the technique was applied successfully to relaxation studies and when analyzing magnetic resonance complicated overlapping spectra. As in course of polymer system irradiation, basically, several type of paramagnetic defects are formed with close values of the g factors, these materials can be used to exemplify NRS capabilities. In this work we use samples of irradiated PMMA copolymers. Analysis of the PMMA spectra shows that several types of paramagnetic defects strongly differing in the spin-lattice relaxation times are formed in irradiated PMMA-based polymer composites. It is found that degradation of the composite physical and engineering characteristics is caused, mainly, by radiation-induced disintegration of macromolecules, following the chain reaction, which can be revealed by occurring lattice radical states. Another portion of work is devoted to NRS application to deterring influence of structural defects (impurity, dislocation, etc.) on variation in times of nuclear spin-lattice relaxation in metal systems. At this stage we managed, for the first time, to separate the distribution functions for spin-lattice relaxation (T{sub l}) and relaxation of nuclear spin dipole-dipole interaction (T{sub d}). It is shown that one can assess an extent of crystal defect by the dependence of T{sub d}=f(c). Also in this work the NRS methods are applied to analyze EPR spectra of polycrystalline solid systems where exchange interaction is strong. It is shown that these systems, as a rule, contain a complete set of spin assemblies having different relaxation times, and the spin assembly distribution over the relaxation time depends on the defect number and

Application of nonlinear EPR and NMR responses on spin systems in structure and relaxation structures

International Nuclear Information System (INIS)

Polyakov, A.I.; Ryabikin, Yu.A.; Bitenbaev, M.M.

2004-01-01

Full text: In this work results of investigation of paramagnetic systems (irradiated polymers and crystals, plastic-deformed metals, systems with strong exchange interaction, etc.) by methods of nonlinear relaxation spectroscopy (NRS) are presented. The NRS theoretical grounds were developed in the earlier works. Later the technique was applied successfully to relaxation studies and when analyzing magnetic resonance complicated overlapping spectra. As in course of polymer system irradiation, basically, several type of paramagnetic defects are formed with close values of the g factors, these materials can be used to exemplify NRS capabilities. In this work we use samples of irradiated PMMA copolymers. Analysis of the PMMA spectra shows that several types of paramagnetic defects strongly differing in the spin-lattice relaxation times are formed in irradiated PMMA-based polymer composites. It is found that degradation of the composite physical and engineering characteristics is caused, mainly, by radiation-induced disintegration of macromolecules, following the chain reaction, which can be revealed by occurring lattice radical states. Another portion of work is devoted to NRS application to deterring influence of structural defects (impurity, dislocation, etc.) on variation in times of nuclear spin-lattice relaxation in metal systems. At this stage we managed, for the first time, to separate the distribution functions for spin-lattice relaxation (T l ) and relaxation of nuclear spin dipole-dipole interaction (T d ). It is shown that one can assess an extent of crystal defect by the dependence of T d =f(c). Also in this work the NRS methods are applied to analyze EPR spectra of polycrystalline solid systems where exchange interaction is strong. It is shown that these systems, as a rule, contain a complete set of spin assemblies having different relaxation times, and the spin assembly distribution over the relaxation time depends on the defect number and type in solid

High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

Science.gov (United States)

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.

High-spin states in 60Cu

International Nuclear Information System (INIS)

Tsan, U.C.; Agard, M.; Bruandet, J.F.; Dauchy, A.; Giorni, A.; Glasser, F.; Morand, C.; Chambon, B.; Drain, D.

1981-04-01

The 60 Cu nucleus has been studied via the 58 Ni(α, pnγ) reaction using different in-beam γ spectroscopy techniques. As for the other odd-odd Cu, the gsub(9/2) shell plays an important role for the explanation of observed high-spin states. Some of them (in particular 6 - and 9 + states) could be interpreted as two-nucleon states in the framework of a crude shell model

Theory of spin-polarized transport in ferromagnet-semiconductor structures: Unified description of ballistic and diffusive transport

International Nuclear Information System (INIS)

Lipperheide, R.; Wille, U.

2006-01-01

A theory of spin-polarized electron transport in ferromagnet-semiconductor heterostructures, based on a unified semiclassical description of ballistic and diffusive transport in semiconductors, is outlined. The aim is to provide a framework for studying the interplay of spin relaxation and transport mechanism in spintronic devices. Transport inside the (nondegenerate) semiconductor is described in terms of a thermoballistic current, in which electrons move ballistically in the electric field arising from internal and external electrostatic potentials, and are thermalized at randomly distributed equilibration points. Spin relaxation is allowed to take place during the ballistic motion. For arbitrary potential profile and arbitrary values of the momentum and spin relaxation lengths, an integral equation for a spin transport function determining the spin polarization in the semiconductor is derived. For field-driven transport in a homogeneous semiconductor, the integral equation can be converted into a second-order differential equation that generalizes the spin drift-diffusion equation. The spin polarization in ferromagnet-semiconductor structures is obtained by matching the spin-resolved chemical potentials at the interfaces, with allowance for spin-selective interface resistances. Illustrative examples are considered

Two-proton radioactivity in proton-rich fp shell nuclei at high spin

Energy Technology Data Exchange (ETDEWEB)

Aggarwal, Mamta [Nuclear Science Centre, Aruna Asaf Ali Marg, Post Box 10502, New Delhi 110067 (India)

2006-07-15

Two-proton radioactivity in extremely proton-rich fp shell nuclei at high spins is investigated in a theoretical framework. Separation energy and entropy fluctuate with spin and hence affect the location of the proton drip line.

Two-proton radioactivity in proton-rich fp shell nuclei at high spin

International Nuclear Information System (INIS)

Aggarwal, Mamta

2006-01-01

Two-proton radioactivity in extremely proton-rich fp shell nuclei at high spins is investigated in a theoretical framework. Separation energy and entropy fluctuate with spin and hence affect the location of the proton drip line

Interfacial symmetry of Co–Alq{sub 3}–Co hybrid structures for effective spin filtering

Energy Technology Data Exchange (ETDEWEB)

Lam, Tu-Ngoc [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Lai, Yu-Ling; Chen, Chih-Han [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Chen, Po-Hung [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Wei, Der-Hsin; Lin, Hong-Ji; Chen, C.T. [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Sheu, Jeng-Tzong, E-mail: jtsheu@faculty.nctu.edu.tw [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Hsu, Yao-Jane, E-mail: yjhsu@nsrrc.org.tw [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC (China); Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

2015-11-01

Graphical abstract: - Highlights: • The spin interface at Alq{sub 3}/Co and Co/Alq{sub 3} contacts was examined. • An interfacial symmetry was determined at Co–Alq{sub 3}–Co interfaces. • Spin-polarized N orbitals are induced within the Co atop Alq{sub 3} hybridized interface. • The spin-filter role at the top contact interface of Alq{sub 3}/Co is proved. • Effective spin-filtering at Co–Alq{sub 3}–Co contacts was elucidated. - Abstract: Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq{sub 3} adsorption on Co, Co/Alq{sub 3}) and the top contact (Co atop Alq{sub 3}, Alq{sub 3}/Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq{sub 3} and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq{sub 3}/Co and Co/Alq{sub 3} heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co–Alq{sub 3}–Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq{sub 3} at both contacts, proving Alq{sub 3} a unique and promising organic material for spin filtering in OSV.

Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Xiaole [Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Xianfeng [The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L., E-mail: clgao@sjtu.edu.cn; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Luo, Weidong, E-mail: wdluo@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)

2016-02-08

Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations.

Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

International Nuclear Information System (INIS)

Zhang, K. F.; Yang, Fang; Song, Y. R.; Zhang, Xiaole; Chen, Xianfeng; Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng; Luo, Weidong

2016-01-01

Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations

Demonstrating Multi-bit Magnetic Memory in the Fe8 High Spin Molecule by Muon Spin Rotation

OpenAIRE

Shafir, Oren; Keren, Amit; Maegawa, Satoru; Ueda, Miki; Amato, Alex; Baines, Chris

2005-01-01

We developed a method to detect the quantum nature of high spin molecules using muon spin rotation, and a three-step field cycle ending always with the same field. We use this method to demonstrate that the Fe8 molecule can remember 6 (possibly 8) different histories (bits). A wide range of fields can be used to write a particular bit, and the information is stored in discrete states. Therefore, Fe8 can be used as a model compound for Multi-bit Magnetic Memory. Our experiment also paves the w...

Spin asymmetries $A_1$ and structure functions $g_1$ of the proton and the deuteron from polarized high energy muon scattering

CERN Document Server

AUTHOR|(CDS)2067425; Arik, E; Arvidson, A; Badelek, B; Bardin, G; Baum, G; Berglund, P; Betev, L; Birsa, R; Björkholm, P; De Botton, N R; Boutemeur, M; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Cavata, C; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garzón, J A; Gilly, H; Giorgi, M A; von Goeler, E; Görtz, S; Golutvin, I A; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kiryushin, Yu T; Kishi, A; Kiselev, Yu F; Klostermann, L; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kukhtin, V V; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nagaitsev, A P; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Pereira, H; Perrot-Kunne, F; Peshekhonov, V D; Piegia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Puntaferro, R; Pussieux, T; Rädel, G; Rijllart, A; Reicherz, G; Roberts, J; Rock, S E; Rodríguez, M; Rondio, Ewa; Ropelewski, Leszek; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schiller, A; Schüler, K P; Seitz, R; Semertzidis, Y K; Sergeev, S; Shanahan, P; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Tessarotto, F; Thers, D; Tlaczala, W; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Ylöstalo, J; Zanetti, A M; Zaremba, K; Zamiatin, N I; Zhao, J

1998-01-01

We present the final results of the spin asymmetries $A_1$ and the spin structure functions $g_1$ of the proton and the deuteron in the kinematic range $0.0008

Spin helical states and spin transport of the line defect in silicene lattice

Energy Technology Data Exchange (ETDEWEB)

Yang, Mou; Chen, Dong-Hai; Wang, Rui-Qiang [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Bai, Yan-Kui, E-mail: ykbai@semi.ac.cn [College of Physical Science and Information Engineering and Hebei Advance Thin Films Laboratory, Hebei Normal University, Shijiazhuang, Hebei 050024 (China)

2015-02-06

We investigated the electronic structure of a silicene-like lattice with a line defect under the consideration of spin–orbit coupling. In the bulk energy gap, there are defect related bands corresponding to spin helical states localized beside the defect line: spin-up electrons flow forward on one side near the line defect and move backward on the other side, and vice versa for spin-down electrons. When the system is subjected to random distribution of spin-flipping scatterers, electrons suffer much less spin-flipped scattering when they transport along the line defect than in the bulk. An electric gate above the line defect can tune the spin-flipped transmission, which makes the line defect as a spin-controllable waveguide. - Highlights: • Band structure of silicene with a line defect. • Spin helical states around the line defect and their probability distribution features. • Spin transport along the line defect and that in the bulk silicene.

High-mobility ultrathin semiconducting films prepared by spin coating.

Science.gov (United States)

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).

High spin states in the f-p shell

International Nuclear Information System (INIS)

Delaunay, J.

1975-01-01

The high spin states (HSS) in Fe, Co, Ni (Z=26,27,28) isotopes exhibit features characteristics of soft or transition nuclei, 56 Fe being as well deformed prolate nucleus and the Ni isotopes often throught of as spherical. The methodology used to identify these HSS is the so called DCO (directional correlation of oriented nuclei) or ratio method which, by combining the angular distribution data plus one point of a triple γ-γ correlation in an asymmetric geometry, gives result that is found equivalent to a complete angular correlation to assign spin and mixing ratios. Some results collected with this methodology are presented [fr

Understanding the proton's spin structure

Energy Technology Data Exchange (ETDEWEB)

Myhrer, Fred [Univ. of South Carolina, Columbia, SC (United States); Thomas, Anthony W. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States)

2010-02-01

We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton "spin crisis" by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.

Measurement of the Spin Structure of the Deuteron in the DIS Region

CERN Document Server

Ageev, E.S.; Alexandrov, Yu.; Alexeev, G.D.; Amoroso, A.; Badelek, B.; Balestra, F.; Ball, J.; Baum, G.; Bedfer, Y.; Berglund, P.; Bernet, C.; Bertini, R.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Bravar, A.; Bressan, A.; Burtin, E.; Bussa, M.P.; Bytchkov, V.N.; Cerini, L.; Chapiro, A.; Cicuttin, A.; Colantoni, M.; Colavita, A.A.; Costa, S.; Crespo, M.L.; d'Hose, N.; Dalla Torre, S.; Dasgupta, S.S.; De Masi, R.; Dedek, N.; Denisov, O.Yu.; Dhara, L.; Diaz Kavka, V.; Dinkelbach, A.M.; Dolgopolov, A.V.; Donskov, S.V.; Dorofeev, V.A.; Doshita, N.; Duic, V.; Dunnweber, W.; Ehlers, J.; Eversheim, P.D.; Eyrich, W.; Fabro, M.; Faessler, M.; Falaleev, V.; Fauland, P.; Ferrero, A.; Ferrero, L.; Finger, M.; Finger, M., Jr.; Fischer, H.; Franz, J.; Friedrich, J.M.; Frolov, V.; Fuchs, U.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gobbo, B.; Goertz, S.; Gorin, A.M.; Grajek, O.; Grasso, A.; Grube, B.; Grunemaier, A.; Hannappel, J.; von Harrach, D.; Hasegawa, T.; Hedicke, S.; Heinsius, F.H.; Hermann, R.; Hess, C.; Hinterberger, F.; von Hodenberg, M.; Horikawa, N.; Horikawa, S.; Ijaduola, R.B.; Ilgner, C.; Ioukaev, A.I.; Ishimoto, S.; Ivanov, O.; Iwata, T.; Jahn, R.; Janata, A.; Joosten, R.; Jouravlev, N.I.; Kabuss, E.; Kalinnikov, V.; Kang, D.; Karstens, F.; Kastaun, W.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu.A.; Khomutov, N.V.; Kisselev, Yu.; Klein, F.; Koblitz, S.; Koivuniemi, J.H.; Kolosov, V.N.; Komissarov, E.V.; Kondo, K.; Konigsmann, Kay; Konoplyannikov, A.K.; Konorov, I.; Konstantinov, V.F.; Korentchenko, A.S.; Korzenev, A.; Kotzinian, A.M.; Koutchinski, N.A.; Kowalik, K.; Kravchuk, N.P.; Krivokhizhin, G.V.; Kroumchtein, Z.V.; Kuhn, R.; Kunne, F.; Kurek, K.; Ladygin, M.E.; Lamanna, M.; Le Goff, J.M.; Leberig, M.; Lichtenstadt, J.; Liska, T.; Ludwig, I.; Maggiora, A.; Maggiora, M.; Magnon, A.; Mallot, G.K.; Manuilov, I.V.; Marchand, C.; Marroncle, J.; Martin, A.; Marzec, J.; Matsuda, T.; Maximov, A.N.; Medved, K.S.; Meyer, W.; Mielech, A.; Mikhailov, Yu.V.; Moinester, M.A.; Nahle, O.; Nassalski, J.; Neliba, S.; Neyret, D.P.; Nikolaenko, V.I.; Nozdrin, A.A.; Obraztsov, V.F.; Olshevsky, A.G.; Ostrick, M.; Padee, A.; Pagano, P.; Panebianco, S.; Panzieri, D.; Paul, S.; Pereira, H.D.; Peshekhonov, D.V.; Peshekhonov, V.D.; Piragino, G.; Platchkov, S.; Platzer, K.; Pochodzalla, J.; Polyakov, V.A.; Popov, A.A.; Pretz, J.; Quintans, C.; Ramos, S.; Rebourgeard, P.C.; Reicherz, G.; Reymann, J.; Rith, K.; Rojdestvenski, A.M.; Rondio, E.; Sadovski, A.B.; Saller, E.; Samoylenko, V.D.; Sandacz, A.; Sapozhnikov, M.G.; Savin, Igor A.; Schiavon, P.; Schill, C.; Schmidt, T.; Schmitt, L.; Schmitt, H.; Shevchenko, O.Yu.; Shishkin, A.A.; Siebert, H.; Sinha, L.; Sissakian, A.N.; Skachkova, A.; Slunecka, M.; Smirnov, G.I.; Sugonyaev, V.P.; Srnka, A.; Stinzing, F.; Stolarski, M.; Sulc, M.; Sulej, R.; Takabayashi, N.; Tchalishev, V.V.; Thers, D.; Tessarotto, F.; Teufel, A.; Tkatchev, L.G.; Toeda, T.; Tretyak, V.I.; Trusov, Sergey V.; Varanda, M.; Virius, M.; Vlassov, N.V.; Wagner, M.; Walcher, T.; Webb, R.; Weise, E.; Weitzel, Q.; Wiesmann, M.; Windmolders, R.; Wirth, S.; Wislicki, W.; Zanetti, A.M.; Zaremba, K.; Zhao, J.; Ziegler, R.; Zvyagin, A.

2005-01-01

We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.

EFFECTS OF SPIN ON HIGH-ENERGY RADIATION FROM ACCRETING BLACK HOLES

Energy Technology Data Exchange (ETDEWEB)

O’ Riordan, Michael; Pe’er, Asaf [Physics Department, University College Cork, Cork (Ireland); McKinney, Jonathan C., E-mail: michael_oriordan@umail.ucc.ie [Department of Physics and Joint Space-Science Institute, University of Maryland, College Park, MD 20742 (United States)

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.

Giant Spin Hall Effect and Switching Induced by Spin-Transfer Torque in a W /Co40Fe40B20/MgO Structure with Perpendicular Magnetic Anisotropy

Science.gov (United States)

Hao, Qiang; Xiao, Gang

2015-03-01

We obtain robust perpendicular magnetic anisotropy in a β -W /Co40Fe40B20/MgO structure without the need of any insertion layer between W and Co40Fe40B20 . This is achieved within a broad range of W thicknesses (3.0-9.0 nm), using a simple fabrication technique. We determine the spin Hall angle (0.40) and spin-diffusion length for the bulk β form of tungsten with a large spin-orbit coupling. As a result of the giant spin Hall effect in β -W and careful magnetic annealing, we significantly reduce the critical current density for the spin-transfer-torque-induced magnetic switching in Co40Fe40B20 . The elemental β -W is a superior candidate for magnetic memory and spin-logic applications.

Nuclear moments of inertia at high spins

International Nuclear Information System (INIS)

Deleplanque, M.A.

1984-01-01

For nuclei in high spin states a yrast-like part of a continuum γ-ray spectrum shows naturally how angular momentum is generated as a function of frequency. In rotational nuclei, the rotational frequency is omega = dE/dI approx. E/sub γ/2, half the collective E2 transition energy. The height of the spectrum for a rotor is proportional to dN/dE/sub γ/ = dI/4d omega. dI/d omega is a dynamic (second derivative of energy with spin) moment of inertia. It contains both alignments and collective effects and is therefore an effective moment of inertia J/sub eff//sup (2)/. It shows how much angular momentum is generated at each frequency. If the collective moment of inertia J/sub band//sup (2)/(omega) is measured (from γ-γ correlation experiments) for the same system, the collective and aligned (Δi) contributions to the increase of angular momentum ΔI in a frequency interval Δ omega can be separated: Δi/ΔI = 1 - J/sub band//sup (2)//J/sub eff//sup (2)/. This is at present the only way to extract such detailed information at the highest spin states where discrete lines cannot be resolved. An example of the spectra obtained in several Er nuclei is shown. They are plotted in units of the moment of inertia J/sub eff//sup (2)/. The high-energy part of the spectra has been corrected for incomplete feeding at these frequencies

A high performance ceria based interdiffusion barrier layer prepared by spin-coating

DEFF Research Database (Denmark)

Plonczak, Pawel; Joost, Mario; Hjelm, Johan

2011-01-01

A multiple spin-coating deposition procedure of Ce0.9Gd0.1O1.95 (CGO) for application in solid oxide fuel cells (SOFCs) was developed. The thin and dense CGO layer can be employed as a barrier layer between yttria stabilised zirconia (YSZ) electrolyte and a (La, Sr)(Co, Fe)O3 based cathode....... The decomposition of the polymer precursor used in the spin-coating process was studied. The depositions were performed on anode supported half cells. By controlling the sintering temperature between each spin-coating process, dense and crack-free CGO films with a thickness of approximately 1 μm were obtained....... The successive steps of dense layer production was investigated by scanning electron microscopy. X-ray diffraction was employed to monitor the crystal structure of the CGO layer sintered at different temperatures. The described spin coated barrier layer was evaluated using an anode supported cell...

Field control of anisotropic spin transport and spin helix dynamics in a modulation-doped GaAs quantum well

Science.gov (United States)

Anghel, S.; Passmann, F.; Singh, A.; Ruppert, C.; Poshakinskiy, A. V.; Tarasenko, S. A.; Moore, J. N.; Yusa, G.; Mano, T.; Noda, T.; Li, X.; Bristow, A. D.; Betz, M.

2018-03-01

Electron spin transport and dynamics are investigated in a single, high-mobility, modulation-doped, GaAs quantum well using ultrafast two-color Kerr-rotation microspectroscopy, supported by qualitative kinetic theory simulations of spin diffusion and transport. Evolution of the spins is governed by the Dresselhaus bulk and Rashba structural inversion asymmetries, which manifest as an effective magnetic field that can be extracted directly from the experimental coherent spin precession. A spin-precession length λSOI is defined as one complete precession in the effective magnetic field. It is observed that application of (i) an out-of-plane electric field changes the spin decay time and λSOI through the Rashba component of the spin-orbit coupling, (ii) an in-plane magnetic field allows for extraction of the Dresselhaus and Rashba parameters, and (iii) an in-plane electric field markedly modifies both the λSOI and diffusion coefficient.

Mean-Field Studies of a Mixed Spin-3/2 and Spin-2 and a Mixed Spin-3/2 and Spin-5/2 Ising System with Different Anisotropies

International Nuclear Information System (INIS)

Wei Guozhu; Miao Hailing

2009-01-01

The magnetic properties of a mixed spin-3/2 and spin-2 and a mixed spin-3/2 and spin-5/2 Ising ferromagnetic system with different anisotropies are studied by means of mean-field theory (MFT). The dependence of the phase diagram on single-ion anisotropy strengths is studied too. In the mixed spin-3/2 and spin-2 Ising model, besides the second-order phase transition, the first order-disorder phase transition and the tricritical line are found. In the mixed spin-3/2 and spin-5/2 Ising model, there is no first-order transition and tricritical line. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Future directions for high-spin studies

International Nuclear Information System (INIS)

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 γ-ray spectra are currently unresolvable. The 4π 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

Quasiparticle band gap of organic-inorganic hybrid perovskites: Crystal structure, spin-orbit coupling, and self-energy effects

Science.gov (United States)

Gao, Weiwei; Gao, Xiang; Abtew, Tesfaye A.; Sun, Yi-Yang; Zhang, Shengbai; Zhang, Peihong

2016-02-01

The quasiparticle band gap is one of the most important materials properties for photovoltaic applications. Often the band gap of a photovoltaic material is determined (and can be controlled) by various factors, complicating predictive materials optimization. An in-depth understanding of how these factors affect the size of the gap will provide valuable guidance for new materials discovery. Here we report a comprehensive investigation on the band gap formation mechanism in organic-inorganic hybrid perovskites by decoupling various contributing factors which ultimately determine their electronic structure and quasiparticle band gap. Major factors, namely, quasiparticle self-energy, spin-orbit coupling, and structural distortions due to the presence of organic molecules, and their influences on the quasiparticle band structure of organic-inorganic hybrid perovskites are illustrated. We find that although methylammonium cations do not contribute directly to the electronic states near band edges, they play an important role in defining the band gap by introducing structural distortions and controlling the overall lattice constants. The spin-orbit coupling effects drastically reduce the electron and hole effective masses in these systems, which is beneficial for high carrier mobilities and small exciton binding energies.

New high spin states and band termination in {sup 83}Y and {sup 84}Zr

Energy Technology Data Exchange (ETDEWEB)

Johnson, T.D.; Aprahamian, A. [University of Notre Dame, Notre Dame, Indiana 46556 (United States); Lister, C.J.; Blumenthal, D.J.; Crowell, B. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chowdhury, P. [University of Massachusetts, Lowell, Massachusetts 01854 (United States); Fallon, P.; Machiavelli, A.O. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

1997-03-01

The gamma decay of high spin yrast states in {sup 83}Y up to I{sup {pi}}=59/2{sup +} and 53/2{sup {minus}} have been observed using the reaction {sup 58}Ni({sup 29}Si,3p) at 110 MeV and the Gammasphere Early Implementation Array. The level scheme has been substantially extended due to the observations of several new transitions in all of the bands. A sequence of transitions feeding into the positive parity yrast band above I{sup {pi}}=47/2{sup +} seems to be consistent with a noncollective oblate structure expected at these high spins. A similar cascade is found in the data for {sup 84}Zr. A new forking of the favored negative parity band is found which may be due to neutron alignment polarizing the core to a different shape. This suggests that the {open_quotes}isomeric{close_quote}{close_quote} band in {sup 83}Y, for which one more connecting transition was found, is of a similar nature to other high-K bands found in this region. Lifetime measurements in the unfavored negative parity band are consistent with cranking calculations which predict a nearly oblate shape with a deformation parameter {beta}{sub 2}{approx}0.2. A qualitative analysis of line shapes at very high spins suggests the persistence of collectivity in the yrast sequence to the highest excitations seen. {copyright} {ital 1997} {ital The American Physical Society}

High-spin studies and nuclear structure in three semi-magic regions of the chart: High-seniority states in Sn isotopes

International Nuclear Information System (INIS)

Astier, A.

2013-01-01

Two fusion-fission experiments have been performed and studied with the Euroball Ge array: 12 C+ 238 U at 90 MeV bombarding energy, and 18 O + 208 Pb at 85 MeV. Among the lot of new information extracted during the last decade, the latest results discussed here are the discovery of the high-spin states of 119-126 Sn. The maximum value of angular momentum available in the Vh 11/2 shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v = 6), has been identified in several tin isotopes. It is the first time that such high-seniority states are established in spherical nuclei. (authors)

Properties of high-spin boson interaction currents and elimination of power divergences

International Nuclear Information System (INIS)

Kulish, Yu.V.; Rybachuk, E.V.

2001-01-01

The problem of the elimination of the power divergences for the interactions of the high-spin bosons (J ≥ 1) is investigated. It is proved that in the consistent theory the high-spin boson interaction currents and the field tensors must obey similar requirements. Therefore the momentum dependencies of the propagators for all the bosons are the same. The partial differential equations derived for some components include the derivatives of order 2J for the currents. Therefore the current components for the spin-J boson must decrease with the momentum Kombi scalar p v Kombi scalar → ∞ at least as Kombi scalar p v Kombi scalar -2J

Spins in the vortices of a high-temperature superconductor

DEFF Research Database (Denmark)

Lake, B.; Aeppli, G.; Clausen, K.N.

2001-01-01

Neutron scattering is used to characterize the magnetism of the vortices for the optimally doped high-temperature superconductor La2-xSrxCuO4 (x = 0.163) in an applied magnetic field. As temperature is reduced, Low-frequency spin fluctuations first disappear with the loss of vortex mobility......, but then reappear. We find that the vortex state can be regarded as an inhomogeneous mixture of a superconducting spin fluid and a material containing a nearly ordered antiferromagnet. These experiments show that as for many other properties of cuprate superconductors, the important underlying microscopic forces...

Spin effects in high- and low-field magnetotransport experiments in semimagnetic Cd1-xMnxTe heterostructures

International Nuclear Information System (INIS)

Betthausen, Christian

2012-01-01

Within the framework of this PhD we report on the very first observation of the fractional Quantum Hall Effect (FQHE) in both, a non-magnetic CdTe and a semimagnetic Cd 1-x Mn x Te quantum well device. To our knowledge, this constitutes the first demonstration of this effect in the II-VI material family. Furthermore, our results reveal that the formation of fractional Quantum Hall states is not inhibited by the presence of magnetic impurities in a quantum structure. The second part of this thesis addresses an alternative route to realize efficient spin transistor action. Typically, spin transistor designs relying on spin-orbit interaction principally suffer from low signal levels due to limitations in spin injection efficiency and fast spin decay. Here we present an approach to realize spin transistor action in systems where spin information is protected by propagating it adiabatically. This is achieved by inducing tunable diabatic Landau-Zener transitions that lead to a backscattering of spins and hence allow controlling the transmission of spin-polarized charge carriers through the device, i.e. switching between 'on' and 'off' states. We demonstrate the validity of our approach in a Cd 1-x Mn x Te diluted magnetic semiconductor quantum well structure where efficient spin transport is observed over device distances of 50 μm. In contrast to other spin transistor designs we find that our concept is exceptionally tolerant against disorder.

Spin-spin interactions of electrons and also of nucleons create atomic molecular and nuclear structures

International Nuclear Information System (INIS)

Kaliambos, L.A.

2008-01-01

Fundamental interactions of spinning electrons at an interelectron separation less than 578.8 fm yield attractive electromagnetic forces with S = 0 creating vibrations under a motional emf. They explain the indistinguishability of electrons and give a vibration energy able for calculating the ground-state energies of many-electron atoms without using any perturbative approximation. Such forces create two-electron orbitals able to account for the exclusion principal and the mechanism of covalent bonds. In the outer subshells of atoms the penetrating orbitals interact also as pair-pair systems and deform drastically the probability densities of the quantum mechanical electron clouds. Such a dynamics of deformation removes the degeneracy and leads to the deviation from the shell scheme. However in the interior of atoms the large nuclear charge leads to a spherically symmetric potential with non-interacting pairs for creating shells of degenerate states giving an accurate explanation of the X-ray lines. On the other hand, considerable charge distributions in nucleons as multiples of 2e/3 and - e/3 determined by the magnetic moments, interact for creating the nuclear structure with p-n bonds. Such spin-spin interactions show that the dominant concept of the untisymmetric wave function for fermions is inapplicable not only in the simple p-n, p-p, and n-n systems but also in the LS coupling of atoms in which the electrons interact from different quantum states giving either S = 0 or S = l. (author)

Roles of quarks and gluons in the spin structure of nucleons

International Nuclear Information System (INIS)

Modarres, M.; Amir-Kabir Univ., Teheran; Ghafoori-Tabrizi, K.; Shahid-Beheshti Univ., Teheran

1992-01-01

The spin structure of protons will be discussed by using MIT-bag model and considering constituent quarks to be combined from current quarks and gluons. It will be shown that the gluonic degrees of freedom play an important role in prediction of the recent EMC results. (orig.)

Spin crossover and Mott—Hubbard transition under high pressure and high temperature in the low mantle of the Earth

Science.gov (United States)

Ovchinnikov, S. G.; Ovchinnikova, T. M.; Plotkin, V. V.; Dyad'kov, P. G.

2015-11-01

Effect of high pressure induced spin crossover on the magnetic, electronic and structural properties of the minerals forming the Earth's low mantle is discussed. The low temperature P, T phase diagram of ferropericlase has the quantum phase transition point Pc = 56 GPa at T = 0 confirmed recently by the synchrotron Mössbauer spectroscopy. The LDA+GTB calculated phase diagram describes the experimental data. Its extension to the high temperature resulted earlier in prediction of the metallic properties of the Earth's mantle at the depth 1400 km insulator transition and compare them with the experimental seismic and geomagnetic field data.

Spin Orbit Interaction Engineering for beyond Spin Transfer Torque memory

Science.gov (United States)

Wang, Kang L.

Spin transfer torque memory uses electron current to transfer the spin torque of electrons to switch a magnetic free layer. This talk will address an alternative approach to energy efficient non-volatile spintronics through engineering of spin orbit interaction (SOC) and the use of spin orbit torque (SOT) by the use of electric field to improve further the energy efficiency of switching. I will first discuss the engineering of interface SOC, which results in the electric field control of magnetic moment or magneto-electric (ME) effect. Magnetic memory bits based on this ME effect, referred to as magnetoelectric RAM (MeRAM), is shown to have orders of magnitude lower energy dissipation compared with spin transfer torque memory (STTRAM). Likewise, interests in spin Hall as a result of SOC have led to many advances. Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures have been shown to arise from the large SOC. The large SOC is also shown to give rise to the large SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. In particular, we will show the magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT is shown to come from the spin-momentum locked surface states of TI, which may further lead to innovative low power applications. I will also describe other related physics of SOC at the interface of anti-ferromagnetism/ferromagnetic structure and show the control exchange bias by electric field for high speed memory switching. The work was in part supported by ERFC-SHINES, NSF, ARO, TANMS, and FAME.

Evolution of nuclear shapes at high spins

International Nuclear Information System (INIS)

Johnson, N.R.

1985-01-01

The dynamic electric quadrupole (E2) moments are a direct reflection of the collective aspects of the nuclear wave functions. For this, Doppler-shift lifetime measurements have been done utilizing primarily the recoil-distance technique. The nuclei with neutron number N approx. 90 possess many interesting properties. These nuclei have very shallow minima in their potential energy surfaces, and thus, are very susceptible to deformation driving influences. It is the evolution of nuclear shapes as a function of spin or rotational frequency for these nuclei that has commanded much interest in the lifetime measurements discussed here. There is growing evidence that many deformed nuclei which have prolate shapes in their ground states conform to triaxial or oblate shapes at higher spins. Since the E2 matrix elements along the yrast line are sensitive indicators of deformation changes, measurements of lifetimes of these states to provide the matrix elements has become the major avenue for tracing the evolving shape of a nucleus at high spin. Of the several nuclei we have studied with N approx. 90, those to be discussed here are /sup 160,161/Yb and 158 Er. In addition, the preliminary, but interesting and surprising results from our recent investigation of the N = 98 nucleus, 172 W are briefly discussed. 14 refs., 5 figs

Polymorphic regenerated silk fibers assembled through bioinspired spinning.

Science.gov (United States)

Ling, Shengjie; Qin, Zhao; Li, Chunmei; Huang, Wenwen; Kaplan, David L; Buehler, Markus J

2017-11-09

A variety of artificial spinning methods have been applied to produce regenerated silk fibers; however, how to spin regenerated silk fibers that retain the advantages of natural silks in terms of structural hierarchy and mechanical properties remains challenging. Here, we show a bioinspired approach to spin regenerated silk fibers. First, we develop a nematic silk microfibril solution, highly viscous and stable, by partially dissolving silk fibers into microfibrils. This solution maintains the hierarchical structures in natural silks and serves as spinning dope. It is then spun into regenerated silk fibers by direct extrusion in the air, offering a useful route to generate polymorphic and hierarchical regenerated silk fibers with physical properties beyond natural fiber construction. The materials maintain the structural hierarchy and mechanical properties of natural silks, including a modulus of 11 ± 4 GPa, even higher than natural spider silk. It can further be functionalized with a conductive silk/carbon nanotube coating, responsive to changes in humidity and temperature.

Relativistic impulse approximation and deuteron spin structure

International Nuclear Information System (INIS)

Tokarev, M.V.

1992-01-01

The fragmentation processes were considered of tensor- and vector-polarized deuterons to protons in the framework of the covariant approach in the light cone variables on the basis of the relativistic deuteron wave function with one nucleon on-mass shell. The experimental verification of predicted dependences of T 20 and K is of interest for the research of the momentum and spin distributions of high momentum deuteron constituents. 21 refs.; 6 figs

Collectivity of high spin states in {sup 84}Zr

Energy Technology Data Exchange (ETDEWEB)

Lister, C.J.; Blumenthal, D.; Crowell, B. [and others

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.

Spin transport at high temperatures in epitaxial Heusler alloy/n-GaAs lateral spin valves

Science.gov (United States)

Peterson, Timothy A.; Christie, Kevin D.; Patel, Sahil J.; Crowell, Paul A.; Palmstrøm, Chris J.

2015-03-01

We report on electrical injection and detection of spin accumulation in ferromagnet/ n-GaAs lateral spin-valve devices, observed up to and above room temperature. The ferromagnet in these measurements is the Heusler alloy Co2FeSi, and the semiconductor channel is GaAs doped at 3 ×1016 cm-3. The spin signal is enhanced by operating the detection contact under forward bias. The enhancement originates from drift effects at low-temperatures and an increase of the detection efficiency at all temperatures. The detector bias dependence of the observed spin-valve signal is interpreted by taking into account the quantum well (QW) which forms in the degenerately doped region immediately behind the Schottky tunnel barrier. In particular, we believe the QW is responsible for the minority spin accumulation (majority spin current) under large forward bias. The spin diffusion length and lifetime are determined by measuring the separation dependence of the non-local spin valve signal in a family of devices patterned by electron beam lithography. A spin diffusion length of 700 nm and lifetime of 46 picoseconds are found at a temperature of 295 K. This work was supported by the NSF under DMR-1104951, the NSF MRSEC program and C-SPIN, a SRC STARNET center sponsored by MARCO and DARPA.

Entanglement entropy in random quantum spin-S chains

International Nuclear Information System (INIS)

Saguia, A.; Boechat, B.; Continentino, M. A.; Sarandy, M. S.

2007-01-01

We discuss the scaling of entanglement entropy in the random singlet phase (RSP) of disordered quantum magnetic chains of general spin S. Through an analysis of the general structure of the RSP, we show that the entanglement entropy scales logarithmically with the size of a block, and we provide a closed expression for this scaling. This result is applicable for arbitrary quantum spin chains in the RSP, being dependent only on the magnitude S of the spin. Remarkably, the logarithmic scaling holds for the disordered chain even if the pure chain with no disorder does not exhibit conformal invariance, as is the case for Heisenberg integer-spin chains. Our conclusions are supported by explicit evaluations of the entanglement entropy for random spin-1 and spin-3/2 chains using an asymptotically exact real-space renormalization group approach

Spin squeezing of atomic ensembles via nuclear-electronic spin entanglement

DEFF Research Database (Denmark)

Fernholz, Thomas; Krauter, Hanna; Jensen, Kasper

2008-01-01

quantum limit for quantum memory experiments and applications in quantum metrology and is thus a complementary alternative to spin squeezing obtained via inter-atom entanglement. Squeezing of the collective spin is verified by quantum state tomography.......We demonstrate spin squeezing in a room temperature ensemble of 1012 Cesium atoms using their internal structure, where the necessary entanglement is created between nuclear and electronic spins of each individual atom. This state provides improvement in measurement sensitivity beyond the standard...

Spin-transfer phenomena in layered magnetic structures: Physical phenomena and materials aspects

International Nuclear Information System (INIS)

Gruenberg, P.; Buergler, D.E.; Dassow, H.; Rata, A.D.; Schneider, C.M.

2007-01-01

During the past 20 years, layered structures consisting of ferromagnetic layers and spacers of various material classes with a thickness of only a few nanometers have revealed a variety of exciting and potentially very useful phenomena not present in bulk material. Representing distinct manifestations of spin-transfer processes, these phenomena may be categorized into interlayer exchange coupling (IEC), giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), and the more recently discovered spin-transfer torque effect leading to current-induced magnetization switching (CIMS) and current-driven magnetization dynamics. These phenomena clearly confer novel material properties on magnetic layered structures with respect to the (magneto-)transport and the magnetostatic as well as magnetodynamic behavior. Here, we will first concentrate on the less well understood aspects of IEC across insulating and semiconducting interlayers and relate the observations to TMR in the corresponding structures. In this context, we will also discuss more recent advances in TMR due to the use of electrodes made from Heusler alloys and the realization of coherent tunneling in epitaxial magnetic tunneling junctions. Finally, we will review our results on CIMS in epitaxial magnetic nanostructures showing that normal and inverse CIMS can occur simultaneously in a single nanopillar device. In all cases discussed, material issues play a major role in the detailed understanding of the spin-transfer effects, in particular in those systems that yield the largest effects and are thus of utmost interest for applications

Role of motive forces for the spin torque transfer for nano-structures

Science.gov (United States)

Barnes, Stewart

2009-03-01

Despite an announced imminent commercial realization of spin transfer random access memory (SPRAM) the current theory evolved from that of Slonczewski [1,2] does not conserve energy. Barnes and Maekawa [3] have shown, in order correct this defect, forces which originate from the spin rather than the charge of an electron must be accounted for, this leading to the concept of spin-motive-forces (smf) which must appear in Faraday's law and which significantly modifies the theory for spin-valves and domain wall devices [4]. A multi-channel theory in which these smf's redirect the spin currents will be described. In nano-structures it is now well known that the Kondo effect is reflected by conductance peaks. In essence, the spin degrees of freedom are used to enhance conduction. In a system with nano-magnets and a Coulomb blockade [5] the similar spin channels can be the only means of effective conduction. This results in a smf which lasts for minutes and an enormous magneto-resistance [5]. This implies the possibility of ``single electron memory'' in which the magnetic state is switched by a single electron. [4pt] [1] J. C. Slonczewski, Current-Driven Excitation of Magnetic Multilayers J. Magn. Magn. Mater. 159, L1 (1996). [0pt] [2] Y. Tserkovnyak, A. Brataas, G. E. W. Bauer, and B. I. Halperin, Nonlocal magnetization dynamics in ferromagnetic heterostructures, Rev. Mod. Phys. 77, 1375 (2005). [0pt] [3] S. E. Barnes and S. Maekawa, Generalization of Faraday's Law to Include Nonconservative Spin Forces Phys. Rev. Lett. 98, 246601 (2007); S. E. Barnes and S. Maekawa, Currents induced by domain wall motion in thin ferromagnetic wires. arXiv:cond-mat/ 0410021v1 (2004). [0pt] [4] S. E., Barnes, Spin motive forces, measurement, and spin-valves. J. Magn. Magn. Mat. 310, 2035-2037 (2007); S. E. Barnes, J. Ieda. J and S. Maekawa, Magnetic memory and current amplification devices using moving domain walls. Appl. Phys. Lett. 89, 122507 (2006). [0pt] [5] Pham-Nam Hai, Byung-Ho Yu

SPIN SUSCEPTIBILITY IN HIGH - TC SUPERCONDUCTIVITY

African Journals Online (AJOL)

USER

2012-07-05

Jul 5, 2012 ... remains unchanged as a result of which the oxygen site will remain deficient ... kinetic energy, a hole's spin hooks up with the random Cu moment to form a ... reach out to each other magnetically to form spin singlet pairs with ...

El strength function at high spin and excitation energy

International Nuclear Information System (INIS)

Barrette, J.

1983-04-01

Recently giant dipole resonance-like concentration of the dipole strength function in nuclei was observed at both high excitation energies and high spins. This observation raises the possibility of obtaining new information on the shape of rapidly rotating heated nuclei. Recent experimental results on this subject are reviewed

A measurement of the proton’s spin structure function g2 at low Q2

Energy Technology Data Exchange (ETDEWEB)

Zhu, Pengjia [Univ. of Science and Technology of China, Hefei (China)

2015-10-21

JLab E08-027, a measurement of g2p and the longitudinal-transverse (LT) spin polarizability, successfully collected data from March to May, 2012. Nucleon spin structure study has been an active research area, which has attracted a very large effort from both experimentalists and theorists. The spin structure study for the last 2 decades has provided us with many exciting and often surprising results. Recently, new precision results in the low-to-intermediate momentum transfer Q2 region from JLab have provided extensive information on the nucleon structure in the confinement region and the transition region between asymptotic free to confinement. In particular, the extensive comparisons of experimental results with Chiral Perturbation Theory (the effective theory of QCD at low energy) calculations show general good agreements, but strong disagreement in the case of the neutron LT spin polarizability. This experiment completed the measurements of gp2 and the LT spin polarizability on the proton in the low-to-intermediate Q2 region. The experiment used a polarized proton (NH3) target for the first time in Hall A. Scattered electrons were detected by a pair of Hall A high resolution spectrometer (HRS) with a pair of septum magnets. To avoid too much depolarization of the target, beam current was limited to 50-100 nA during the experiment. Since the existing beam current monitors (BCMs), beam position monitors (BPMs) and calibration methods did not work at such a low current range, new BPM and BCM receivers were designed and used for current condition. A pair of super-harps and a tungsten calorimeter were installed to calibrate the BPMs and BCMs. To compensate for the effect of the 2.5/5T transverse magnet field, two chicane dipole magnets were installed. A pair of slow rasters were installed for the first time in Hall A, combining with a pair of fast raster. The standard Hall A DAQ system and the improved high resolution DAQ system were used to record the detector

Spin Dependent Electronic Structure of Doped Manganese Perovskites

International Nuclear Information System (INIS)

Park, J.-H.

1999-01-01

The spin-resolved photoemission spectra were successfully obtained from La0.7Sr0.3MnO3 190 nm thick epitaxial film on SrTiO3(001). Well below Tc the results clearly manifest the half-metallic nature, i.e., for the majority spin, the photoemission spectrum clearly shows a metallic Fermi cut-off, whereas for the minority spin, it shows an insulating gap with disappearance of the spectral weight at ∼0.6 eV binding energy. On heating through Tc the spectra show no difference for different spins and the spectra weight at the Fermi level (EF disappears, indicating that the Mn 3d spins become disordered) and the system undergoes the ferromagnetic metal to paramagnetic non-metal transition. (c) 2000 American Vacuum Society

Spin electronics

CERN Document Server

Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

2004-01-01

This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

Spin Hall effects

Science.gov (United States)

Sinova, Jairo; Valenzuela, Sergio O.; Wunderlich, J.; Back, C. H.; Jungwirth, T.

2015-10-01

Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical

High-field study of the spin-Peierls system CuGeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Regnault, L P [CEA Centre d` Etudes de Grenoble, 38 (France)

1997-04-01

The one-dimensional spin-1/2 Heisenberg antiferromagnetic system coupled to a three-dimensional phonon field undergoes a structural distortion below a finite temperature T{sub sp} (spin-Peierls transition) which induces the formation of a non-magnetic singlet ground-state and the opening of a gap in the excitation spectrum at the antiferromagnetic point. The recent discovery of the germanate CuGeO{sub 3} as a spin-Peierls system has considerably renewed the interest is this fascinating phenomenon. Inelastic neutron scattering and neutron diffraction have brought very quantitative pieces of information which can be directly compared to the predictions of the standard model. (author). 6 refs.

One-step patterning of double tone high contrast and high refractive index inorganic spin-on resist

Energy Technology Data Exchange (ETDEWEB)

Zanchetta, E.; Della Giustina, G.; Brusatin, G. [Industrial Engineering Department and INSTM, Via Marzolo 9, 35131 Padova (Italy)

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.

Recent trends in spin-resolved photoelectron spectroscopy

Science.gov (United States)

Okuda, Taichi

2017-12-01

Since the discovery of the Rashba effect on crystal surfaces and also the discovery of topological insulators, spin- and angle-resolved photoelectron spectroscopy (SARPES) has become more and more important, as the technique can measure directly the electronic band structure of materials with spin resolution. In the same way that the discovery of high-Tc superconductors promoted the development of high-resolution angle-resolved photoelectron spectroscopy, the discovery of this new class of materials has stimulated the development of new SARPES apparatus with new functions and higher resolution, such as spin vector analysis, ten times higher energy and angular resolution than conventional SARPES, multichannel spin detection, and so on. In addition, the utilization of vacuum ultra violet lasers also opens a pathway to the realization of novel SARPES measurements. In this review, such recent trends in SARPES techniques and measurements will be overviewed.

Spin quenching assisted by a strongly anisotropic compression behavior in MnP

Energy Technology Data Exchange (ETDEWEB)

Han, Fei; Wang, Di; Wang, Yonggang; Li, Nana; Bao, Jin-Ke; Li, Bing; Botana, Antia S.; Xiao, Yuming; Chow, Paul; Chung, Duck Young; Chen, Jiuhua; Wan, Xiangang; Kanatzidis, Mercouri G.; Yang, Wenge; Mao, Ho-Kwang

2018-02-01

We studied the crystal structure and spin state of MnP under high pressure with synchrotron X-ray diffraction and X-ray emission spectroscopy. MnP has an exceedingly strong anisotropy in compressibility, with the primary compressible direction along the b axis of the Pnma structure. X-ray emission spectroscopy reveals a pressure-driven quenching of the spin state in MnP. First-principles calculations suggest that the strongly anisotropic compression behavior significantly enhances the dispersion of the Mn d-orbitals and the splitting of the d-orbital levels compared to the hypothetical isotropic compression behavior. Thus, we propose spin quenching results mainly from the significant enhancement of the itinerancy of d electrons and partly from spin rearrangement occurring in the split d-orbital levels near the Fermi level. This explains the fast suppression of magnetic ordering in MnP under high pressure. The spin quenching lags behind the occurrence of superconductivity at ~8 GPa implying that spin fluctuations govern the electron pairing for superconductivity.

Spin dynamics in relativistic ionization with highly charged ions in super-strong laser fields

International Nuclear Information System (INIS)

Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Müller, Carsten; Paulus, Gerhard G

2014-01-01