Extraction of Spin-Orbit Interactions from Phase Shifts via Inversion

International Nuclear Information System (INIS)

Lun, D.R.; Buckman, S.J.

1997-01-01

An exact inversion procedure for obtaining the central and spin-orbit potential from phase shifts at fixed energy is described. The method, based on Sabatier interpolation formulas, reduces the nonlinear problem to linear-algebraic equations. We have tested the method with a Woods-Saxon potential with a strong spin-orbit component. copyright 1997 The American Physical Society

Topics in phase-shift analysis and higher spin field theory

International Nuclear Information System (INIS)

Reisen, J.C.J.M.

1983-01-01

The first part of this thesis considers several aspects of the existence of phase-shift ambiguities. The subject is introduced with a few remarks on scattering theory and previous work in this area is discussed. The mathematical restrictions of presenting such problems clearly are considered and the construction of different unitary amplitudes which correspond to the same differential cross section is described. So far, examples of phase-shift ambiguities have only been found for rather special cases but the author shows that these results can be considerably generalized for spinless elastic scattering, leading to properties of phase-shift ambiguities being revealed that were previously absent. These properties are discussed in detail. Phase-shift ambiguities for the spin-0-spin-1/2 elastic scattering are then considered and again generalized. The second part of this thesis is concerned with the investigation of a free field theory for both massive and massless particles with higher spin (1, 2 and 3). A root method has been used which is described and shown to lead to the free field equations and the subsidiary conditions. A field equation and Lagrangian are constructed for massive particles and the former is then used to derive a massless field equation and Lagrangian. The relation between massive and massless field equations is investigated in more detail and particularly the expressions for the amplitude describing exchange of a particle between two external sources are compared. (Auth./C.F.)

Spectroscopic measurement of 204Pb isotope shift and 205Pb nuclear spin

International Nuclear Information System (INIS)

Schonberger, P.

1984-01-01

The isotope shift of 204 Pb and the nuclear spin of 1.4 X 10 7 -y 205 Pb was determined from a high-resolution optical measurement of the 6p 23 P 0 -6p7s 3 P 1 0 283.3-nm resonance line. The value of the shift, relative to 208 Pb is -140.2(8) x 10 -3 cm -1 , the negative sign indicating a shift to lower wave numbers. The precision is 3-4 times greater than that of previous measurements. The spin of 205 Pb I = 5/2 was obtained from the measurement of the relative intensities of its three hyperfine components. This method of absorption spectroscopy determination of ground state nuclear spin is applicable to any stable or long-lived isotope. High resolution optical absorption spectra were obtained with a 25.4 cm diffraction grating in a 9.1 m focal length Czerny-Turner spectrometer. A signal-averaging scanning technique was used to record the spectra. Increased precision in the isotope shift measurement was attained by using separated isotope samples of 204 Pb and 207 Pb

Spectroscopic Measurement of LEAD-204 Isotope Shift and LEAD-205 Nuclear Spin.

Science.gov (United States)

Schonberger, Peter

The isotope shift of ('204)Pb and the nuclear spin of 1.4 x 10('7)-y ('205)Pb was determined from a high -resolution optical measurement of the 6p('2) ('3)P(,o) -6p7s('3)P(,1)('o) 283.3-nm resonance line. The value of the shift, relative to ('208)Pb is -140.2(8) x 10('-3)cm(' -1), the negative sign indicating a shift to lower wave numbers. The precision is 3-4 times greater than that of previous measurements. The spin of ('205)Pb l = 5/2 was obtained from the measurement of the relative intensities of its three hyperfine components. This method of absorption spectroscopy determination of ground state nuclear spin is applicable to any stable or longlived isotope. High resolution optical absorption spectra were obtained with a 25.4cm diffraction grating in a 9.1m focal length Czerny-Turner spectrometer. A signal-averaging scanning technique was used to record the spectra. Increased precision in the isotope shift measurement was attained by using separated isotope samples of ('204)Pb and ('207)Pb. A controlled amount of the later was incorporated in the absorption cell to provide internal calibration by its 6p7s ('3)P(,1)('o) hfs separation. Absorption spectra were recorded for several optical thicknesses of the absorber. A single spin value of increased precision was derived from the entire set of combined data.

Portable shift register

International Nuclear Information System (INIS)

Halbig, J.K.; Bourret, S.C.; Hansen, W.J.; Hicks, D.V.; Klosterbuer, S.F.; Krick, M.S.

1994-01-01

An electronics package for a small, battery-operated, self-contained, neutron coincidence counter based on a portable shift-register (PSR) has been developed. The counter was developed for applications not adequately addressed by commercial packages, including in-plant measurements to demonstrate compliance with regulations (domestic and international), in-plant process control, and in-field measurements (environmental monitoring or safeguards). Our package's features, which address these applications, include the following: Small size for portability and ease of installation;battery or mains operation; a built-in battery to power the unit and a typical detector such as a small sample counter, for over 6 h if power lines are bad or noisy, if there is a temporary absence of power, or if portability is desired; complete support, including bias, for standard neutron detectors; a powerful communications package to easily facilitate robust external control over a serial port; and a C-library to simplify creating external control programs in computers or other controllers. Whereas the PSR specifically addresses the applications mentioned above, it also performs all the measurements made by previous electronics packages for neutron coincidence counters developed at Los Alamos and commercialized. The PSR electronics package, exclusive of carrying handle, is 8 by 10 by 20 cm; it contains the circuit boards, battery, and bias supply and weighs less than 2 kg. This instrument package is the second in an emerging family of portable measurement instruments being developed; the first was the Miniature and Modular Multichannel Analyzer (M 3 CA). The PSR makes extensive use of hardware and software developed for the M 3 CA; like the M 3 CA, it is intended primarily for use with an external controller interfaced over a serial channel

The synthesis of the correlation function of pseudorandom binary numbers at the output shift register

Science.gov (United States)

Galustov, G. G.; Voronin, V. V.

2017-05-01

The sequence generator generates a sequence of pseudorandom binary numbers using a linear-feedback shift register (LFSR). This block implements LFSR using a simple shift register generator (SSRG, or Fibonacci) configuration. In this article we introduce the concept of probabilistic binary element provides requirements, which ensure compliance with the criterion of "uniformity" in the implementation of the basic physical generators uniformly distributed random number sequences. Based on these studies, we obtained an analytic relation between the parameters of the binary sequence and parameters of a numerical sequence with the shift register output. The received analytical dependencies can help in evaluating the statistical characteristics of the processes in solving problems of statistical modeling. It is supposed that the formation of the binary sequence output from the binary probabilistic element is produced using a physical noise process. It is shown that the observed errors in statistical modeling using pseudo-random numbers do not occur if the model examines linear systems with constant parameters, but in case models of nonlinear systems, higher order moments can have a Gaussian distribution.

Development of a multistop TDC using a shift register for muon decay measurements in a pulsed beam

International Nuclear Information System (INIS)

Shimokoshi, F.; Kuno, Y.; Nagamine, K.; Yamazaki, T.; Tokyo Univ.

1990-01-01

New multistop CAMAC TDC modules using shift registers have been developed and were successfully used to measure the time spectrum of electrons from μ→eνanti ν decay in a high-intensity pulsed muon beam available at the UT-MSL/BOOM facility at KEK in Japan and after that also at Rutherford Appleton Laboratory. The time resolution of the TDC is as good as 16 ns. Among many features of the TDC, the combination of the shift register with fast memories is notable. By adopting this, the time range of the TDC can be extendable beyond the shift register depth without losing time resolution. The other feature is capability of making histograms in its own huge memories. The principle of operation and the performance of the TDC are described. (orig.)

High-temperature superconducting shift registers operating at up to 100 GHz

International Nuclear Information System (INIS)

Martens, J.S.; Pance, A.; Char, K.

1994-01-01

Shift registers have been demonstrated in YBaCuO operating at 77 K using from 64 to over 1,000 junctions. These are some of the larger scale integrated circuits demonstrated to date using YBaCuO Josephson technology. The circuit is a modified rapid single flux quantum design in which a single trigger pulse causes a one bit shift of the entire word of 32--512 b in length. Two different junction technologies, electron-beam defined nanobridges and epitaxial edge junctions, have been used with parameter spreads ranging from 11% to 22%. Correct operation has been verified with low speed random word tests and circulating data tests while pseudo random bit sequence demonstrations are underway. A practical amount of time to shift between cells has been measured to be about 10 ps

40-Gbit/s all-optical circulating shift register with an inverter.

Science.gov (United States)

Hall, K L; Donnelly, J P; Groves, S H; Fennelly, C I; Bailey, R J; Napoleone, A

1997-10-01

We report what is believed to be the first demonstration of an all-optical circulating shift register using an ultrafast nonlinear interferometer with a polarization-insensitive semiconductor optical amplifier as the nonlinear switching element. The device operates at 40 Gbits/s, to our knowledge the highest speed demonstrated to date. Also, the demonstration proves the cascadability of the ultrafast nonlinear interferometric switch.

Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols.

Science.gov (United States)

Nacsa, Eric D; MacMillan, David W C

2018-03-07

Nature routinely engages alcohols as leaving groups, as DNA biosynthesis relies on the removal of water from ribonucleoside diphosphates by a radical-mediated "spin-center shift" (SCS) mechanism. Alcohols, however, remain underused as alkylating agents in synthetic chemistry due to their low reactivity in two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide evidence for SCS as a key elementary step, identify the origins of competing reactions, and enable improvements in chemoselectivity by rational photocatalyst design.

Modeling the hyperfine state selectivity of a short lamb-shift spin-filter polarimeter

International Nuclear Information System (INIS)

Mendez, A.J.; Roper, C.D.; Clegg, T.B.

1995-01-01

An rf cavity, previously used as a spin filter in a Lamb-shift polarized ion source, is being adapted for use as a polarimeter in an atomic beam polarized hydrogen and deuterium ion source. Paramount among the design criteria is maintaining the current source performance while providing on-line beam polarization monitoring. This requires minimizing both the polarimeter system length and the coupling with the magnetic fields of the other ion source systems. Detailed computer calculations have modeled the four-level interaction involving the 2S 1/2 -2P 1/2 states of the atomic beam. These indicate that a significantly shorter spin-filter cavity and uniform axial magnetic field than used in the Lamb-shift source do not compromise the spin-state selectivity. The calculations also predict the axial magnetic field uniformity needed as well as the gains achieved from proper shaping of the cavity rf and dc fields. copyright 1995 American Institute of Physics

Accurate 3He polarimetry using the Rb Zeeman frequency shift due to the Rb-3He spin-exchange collisions

International Nuclear Information System (INIS)

Romalis, M.V.; Cates, G.D.

1998-01-01

We describe a method of 3 He polarimetry relying on the polarization-dependent frequency shift of the Rb Zeeman resonance. Our method is ideally suited for on-line measurements of the 3 He polarization produced by spin-exchange optical pumping. To calibrate the frequency shift we performed an accurate measurement of the imaginary part of the Rb- 3 He spin-exchange cross section in the temperature range typical for spin-exchange optical pumping of 3 He. We also present a detailed study of possible systematic errors in the frequency shift polarimetry. copyright 1998 The American Physical Society

Sorting photons of different rotational Doppler shifts (RDS) by orbital angular momentum of single-photon with spin-orbit-RDS entanglement.

Science.gov (United States)

Chen, Lixiang; She, Weilong

2008-09-15

We demonstrate that single photons from a rotating q-plate exhibit an entanglement in three degrees of freedom of spin, orbital angular momentum, and the rotational Doppler shift (RDS) due to the nonconservation of total spin and orbital angular momenta. We find that the rotational Doppler shift deltaomega = Omega((delta)s + deltal) , where s, l and Omega are quantum numbers of spin, orbital angular momentum, and rotating velocity of the q-plate, respectively. Of interest is that the rotational Doppler shift directly reflects the rotational symmetry of q-plates and can be also expressed as deltaomega = (Omega)n , where n = 2(q-1) denotes the fold number of rotational symmetry. Besides, based on this single-photon spin-orbit-RDS entanglement, we propose an experimental scheme to sort photons of different frequency shifts according to individual orbital angular momentum.

Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

Directory of Open Access Journals (Sweden)

X. H. Liu

2015-10-01

Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

Spin-echo based diagonal peak suppression in solid-state MAS NMR homonuclear chemical shift correlation spectra

Science.gov (United States)

Wang, Kaiyu; Zhang, Zhiyong; Ding, Xiaoyan; Tian, Fang; Huang, Yuqing; Chen, Zhong; Fu, Riqiang

2018-02-01

The feasibility of using the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed in such a way that in the indirect dimension only the spin diffused signals are evolved, while all signals not involved in polarization transfer are refocused for cancellation. A data processing procedure is further introduced to reconstruct this acquired spectrum into a conventional two-dimensional homonuclear chemical shift correlation spectrum. A uniformly 13C, 15N labeled Fmoc-valine sample and the transmembrane domain of a human protein, LR11 (sorLA), in native Escherichia coli membranes have been used to illustrate the capability of the proposed method in comparison with standard 13C-13C chemical shift correlation experiments.

Muonium spin exchange in spin-polarized media: Spin-flip and -nonflip collisions

International Nuclear Information System (INIS)

Senba, M.

1994-01-01

The transverse relaxation of the muon spin in muonium due to electron spin exchange with a polarized spin-1/2 medium is investigated. Stochastic calculations, which assume that spin exchange is a Poisson process, are carried out for the case where the electron spin polarization of the medium is on the same axis as the applied field. Two precession signals of muonium observed in intermediate fields (B>30 G) are shown to have different relaxation rates which depend on the polarization of the medium. Furthermore, the precession frequencies are shifted by an amount which depends on the spin-nonflip rate. From the two relaxation rates and the frequency shift in intermediate fields, one can determine (i) the encounter rate of muonium and the paramagnetic species, (ii) the polarization of the medium, and most importantly (iii) the quantum-mechanical phase shift (and its sign) associated with the potential energy difference between electron singlet and triplet encounters. Effects of spin-nonflip collisions on spin dynamics are discussed for non-Poisson as well as Poisson processes. In unpolarized media, the time evolution of the muon spin in muonium is not influenced by spin-nonflip collisions, if the collision process is Poissonian. This seemingly obvious statement is not true anymore in non-Poissonian processes, i.e., it is necessary to specify both spin-flip and spin-nonflip rates to fully characterize spin dynamics

INVESTIGATION OF FLIP-FLOP PERFORMANCE ON DIFFERENT TYPE AND ARCHITECTURE IN SHIFT REGISTER WITH PARALLEL LOAD APPLICATIONS

Directory of Open Access Journals (Sweden)

Dwi Purnomo

2015-08-01

Full Text Available Register is one of the computer components that have a key role in computer organisation. Every computer contains millions of registers that are manifested by flip-flop. This research focuses on the investigation of flip-flop performance based on its type (D, T, S-R, and J-K and architecture (structural, behavioural, and hybrid. Each type of flip-flop on each architecture would be tested in different bit of shift register with parallel load applications. The experiment criteria that will be assessed are power consumption, resources required, memory required, latency, and efficiency. Based on the experiment, it could be shown that D flip-flop and hybrid architecture showed the best performance in required memory, latency, power consumption, and efficiency. In addition, the experiment results showed that the greater the register number, the less efficient the system would be.

Chemical shift-based identification of monosaccharide spin-systems with NMR spectroscopy to complement untargeted glycomics.

Science.gov (United States)

Klukowski, Piotr; Schubert, Mario

2018-06-15

A better understanding of oligosaccharides and their wide-ranging functions in almost every aspect of biology and medicine promises to uncover hidden layers of biology and will support the development of better therapies. Elucidating the chemical structure of an unknown oligosaccharide is still a challenge. Efficient tools are required for non-targeted glycomics. Chemical shifts are a rich source of information about the topology and configuration of biomolecules, whose potential is however not fully explored for oligosaccharides. We hypothesize that the chemical shifts of each monosaccharide are unique for each saccharide type with a certain linkage pattern, so that correlated data measured by NMR spectroscopy can be used to identify the chemical nature of a carbohydrate. We present here an efficient search algorithm, GlycoNMRSearch, that matches either a subset or the entire set of chemical shifts of an unidentified monosaccharide spin system to all spin systems in an NMR database. The search output is much more precise than earlier search functions and highly similar matches suggest the chemical structure of the spin system within the oligosaccharide. Thus searching for connected chemical shift correlations within all electronically available NMR data of oligosaccharides is a very efficient way of identifying the chemical structure of unknown oligosaccharides. With an improved database in the future, GlycoNMRSearch will be even more efficient deducing chemical structures of oligosaccharides and there is a high chance that it becomes an indispensable technique for glycomics. The search algorithm presented here, together with a graphical user interface, is available at http://glyconmrsearch.santos.pwr.edu.pl. Supplementary data are available at Bioinformatics online.

Neutron spin quantum precession using multilayer spin splitters and a phase-spin echo interferometer

International Nuclear Information System (INIS)

Ebisawa, Toru; Tasaki, Seiji; Kawai, Takeshi; Hino, Masahiro; Akiyoshi, Tsunekazu; Achiwa, Norio; Otake, Yoshie; Funahashi, Haruhiko.

1996-01-01

Neutron spin quantum precession by multilayer spin splitter has been demonstrated using a new spin interferometer. The multilayer spin splitter consists of a magnetic multilayer mirror on top, followed by a gap layer and a non magnetic multilayer mirror which are evaporated on a silicon substrate. Using the multilayer spin splitter, a polarized neutron wave in a magnetic field perpendicular to the polarization is split into two spin eigenstates with a phase shift in the direction of the magnetic field. The spin quantum precession is equal to the phase shift, which depends on the effective thickness of the gap layer. The demonstration experiments verify the multilayer spin splitter as a neutron spin precession device as well as the coherent superposition principle of the two spin eigenstates. We have developed a new phase-spin echo interferometer using the multilayer spin splitters. We present successful performance tests of the multilayer spin splitter and the phase-spin echo interferometer. (author)

Scheduling and shift work characteristics associated with risk for occupational injury in newly licensed registered nurses: An observational study.

Science.gov (United States)

Stimpfel, Amy Witkoski; Brewer, Carol S; Kovner, Christine T

2015-11-01

Registered nurses across the globe bear a heavy injury burden. Every shift, nurses are exposed to a variety of hazards that can jeopardize their health, which negatively impacts their ability to provide high-quality patient care. Previous research suggests that inexperienced, or newly licensed nurses, may have an increased risk for certain occupational injuries. However, the current knowledge base is insufficient to fully understand how work hours influence newly licensed nurses' occupational injury, given the significant variation in hospital organization and work characteristics. To describe newly licensed nurses' shift work characteristics and determine the association between shift type and scheduling characteristics and nurse injury, before and after adjusting for individual and combined effects of demographics, external context, organizational context, and work context, following the Organization of Work model. This study is a secondary analysis of a nationally representative survey of newly licensed registered nurses using a cross-sectional design. The analytic sample includes 1744 newly licensed registered nurses from 34 states and the District of Columbia who reported working in a hospital and were within 6-18 months of passing their state licensure exam at the time of survey administration. Descriptive statistics were calculated, followed by bivariate and multivariate Poisson regression models to assess the relationship between shift type and scheduling characteristics and nurse injury. Lastly, full models with the addition of demographics, external context, organizational context, and work context variables were calculated. The majority (79%) of newly licensed nurses worked 12-h shifts, a near majority worked night shift (44%), and over half (61%) worked overtime (mandatory or voluntary) weekly. Nurses working weekly overtime were associated with a 32% [incidence rate ratio (IRR) 1.32, CI 1.07-1.62] increase in the risk of a needle stick and nurses

Fast event recorder utilizing a CCD analog shift register

International Nuclear Information System (INIS)

Ducar, R.J.; McIntyre, P.M.

1978-01-01

A system of electronics has been developed to allow the capture and recording of relatively fast, low-amplitude analog events. The heart of the system is a dual 455-cell analog shift register charge-coupled device, Fairchild CCD321ADC-3. The CCD is operated in a dual clock mode. The input is sampled at a selectable clock rate of .25-20 MHz. The stored analog data is then clocked out at a slower rate, typically about .25 MHz. The time base expansion of the analog data allows for analog-to-digital conversion and memory storage using conventional medium-speed devices. The digital data is sequentially loaded into a static RAM and may then be block transferred to a computer. The analog electronics are housed in a single-width NIM module, and the RAM memory in a single-width CAMAC module. Each pair of modules provides six parallel channels. Cost is about $200.00 per channel. Applications are described for ionization imaging (TPC, IRC) and long-drift calorimetry in liquid argon

Estimating the Dieaway Time and its Precision from Shift Register Data

Energy Technology Data Exchange (ETDEWEB)

Croft, S.; Evans, L. G.; Henzlova, D.; Miller, K. A. [Los Alamos National Laboratory, Nuclear Nonproliferation Division, Safeguards Science and Technology Group, Los Alamos (United States)

2012-06-15

Neutron coincidence counting is widely used throughout the nuclear fuel cycle to quantify special nuclear materials that fission, for example Pu. Before calibration and setting to work, instruments undergo a range of performance and characterization tests that typically include measurement of the neutron dieaway characteristic. The neutron dieaway characteristic is a general measure of the likelihood that a neutron will be detected following another neutron, and describes time behavior of detected neutrons in the assay system. This paper shows how the effective 1/ecapture dieaway time of the observable coincidence (doubles) rate may be extracted simply and quickly from two coincidence counting rates recorded with different shift register time gate settings. In particular we address how to assign the precision to such estimates including when the rates are correlated.

KN phase shifts in a model with a spin-orbit interaction

International Nuclear Information System (INIS)

Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

2001-01-01

The I=1 and I=0 kaon-nucleon s, p, d, f, g-waves phase shifts have been calculated in a non relativistic quark potential model using the resonating group method (RGM). The interquark potential includes gluon exchanges with a spin-orbit interaction. This force was determined to reproduce as well as possible the meson and baryon spectra. The same force is employed for the cluster and intercluster dynamics and the relative KN wave function is calculated without any approximation. While some channels are correctly described, the theory is still unable to explain others

Electric-field assisted spin torque nano-oscillator and binary frequency shift keying modulation

Science.gov (United States)

Zhang, Xiangli; Chen, Hao-Hsuan; Zhang, Zongzhi; Liu, Yaowen

2018-04-01

Electric-controlled magnetization precession introduces technologically relevant possibility for developing spin torque nano-oscillators (STNO) with potential applications in microwave emission. Using the perpendicularly magnetized magnetic tunnel junction (MTJ), we show that the magnetization oscillation frequency can be tuned by the co-action of electric field and spin polarized current. The dynamical phase diagram of MTJ-based STNO is analytically predicted through coordinate transformation from the laboratory frame to the rotation frame, by which the nonstationary out-of-plane magnetization precession process is therefore transformed into the stationary process in the rotation frame. Furthermore, using this STNO as a microwave source, we numerically demonstrate that the bit signal can be transmitted by a binary frequency shift keying (BFSK) modulation technique. The BFSK scheme shows good modulation features with no transient state.

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device

International Nuclear Information System (INIS)

Lambropoulos, Nicholas A; Reimers, Jeffrey R; Crossley, Maxwell J; Hush, Noel S; Silverbrook, Kia

2013-01-01

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology. (paper)

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device

Science.gov (United States)

Lambropoulos, Nicholas A.; Reimers, Jeffrey R.; Crossley, Maxwell J.; Hush, Noel S.; Silverbrook, Kia

2013-12-01

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device.

Science.gov (United States)

Lambropoulos, Nicholas A; Reimers, Jeffrey R; Crossley, Maxwell J; Hush, Noel S; Silverbrook, Kia

2013-12-20

A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

Bi-stable vocal fold adduction: a mechanism of modal-falsetto register shifts and mixed registration.

Science.gov (United States)

Titze, Ingo R

2014-04-01

The origin of vocal registers has generally been attributed to differential activation of cricothyroid and thyroarytenoid muscles in the larynx. Register shifts, however, have also been shown to be affected by glottal pressures exerted on vocal fold surfaces, which can change with loudness, pitch, and vowel. Here it is shown computationally and with empirical data that intraglottal pressures can change abruptly when glottal adductory geometry is changed relatively smoothly from convergent to divergent. An intermediate shape between large convergence and large divergence, namely, a nearly rectangular glottal shape with almost parallel vocal fold surfaces, is associated with mixed registration. It can be less stable than either of the highly angular shapes unless transglottal pressure is reduced and upper stiffness of vocal fold tissues is balanced with lower stiffness. This intermediate state of adduction is desirable because it leads to a low phonation threshold pressure with moderate vocal fold collision. Achieving mixed registration consistently across wide ranges of F0, lung pressure, and vocal tract shapes appears to be a balancing act of coordinating laryngeal muscle activation with vocal tract pressures. Surprisingly, a large transglottal pressure is not facilitative in this process, exacerbating the bi-stable condition and the associated register contrast.

A Synoptic of Software Implementation for Shift Registers Based on 16th Degree Primitive Polynomials

Directory of Open Access Journals (Sweden)

Mirella Amelia Mioc

2016-08-01

Full Text Available Almost all of the major applications in the specific Fields of Communication used a well-known device called Linear Feedback Shift Register. Usually LFSR functions in a Galois Field GF(2n, meaning that all the operations are done with arithmetic modulo n degree Irreducible  and especially  Primitive Polynomials. Storing data in Galois Fields allows effective and manageable manipulation, mainly in computer cryptographic applications. The analysis of functioning for Primitive Polynomials of 16th degree shows that almost all the obtained results are in the same time distribution.

Nuclear spin relaxation due to chemical shift anisotropy of gas-phase 129Xe.

Science.gov (United States)

Hanni, Matti; Lantto, Perttu; Vaara, Juha

2011-08-14

Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrized ab initio binary nuclear shielding tensors, an "NMR force field". By using the Redfield relaxation formalism, the simulated CSA time correlation functions lead to spectral density functions that, for the first time, quantitatively determine the experimental spin-lattice relaxation times T(1). The quality requirements on both the Xe-Xe interaction potential and binary shielding tensor are investigated in the context of CSA T(1). Persistent dimers Xe(2) are found to be responsible for the CSA relaxation mechanism in the low-density limit of the gas, completely in line with the earlier experimental findings.

Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained.

Science.gov (United States)

Vícha, Jan; Komorovsky, Stanislav; Repisky, Michal; Marek, Radek; Straka, Michal

2018-05-10

The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic structure and SO-HALA effect has been missing. By analyzing 1 H NMR chemical shifts of the sixth-period hydrides (Cs-At), we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d 2 -5d 8 and 6p 4 HA hydrides and deshielded in 4f 0 , 5d 0 , 6s 0 , and 6p 0 HA hydrides. This general and intuitive concept explains periodic trends in the 1 H NMR chemical shifts along the sixth-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to nonhydride LAs. The decades-old question of why compounds with occupied frontier π molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier σ MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property that can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of a magnetic field. Using an analogy between the SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide

What's my line? A narrative review and synthesis of the literature on Registered Nurses' communication behaviours between shifts.

Science.gov (United States)

Kitson, Alison L; Muntlin Athlin, Åsa; Elliott, Janice; Cant, Megan L

2014-06-01

To describe, appraise and synthesize the seminal and empirical literature around Registered Nurses' communication behaviours between shifts in acute hospital settings. Effective communication between shifts (at nursing handover) is acknowledged as a prerequisite to safe and high-quality patient-centred care. However, gaps and inconsistencies continue to prevail. Narrative review and synthesis. The electronic databases PubMED, CINAHL and Scopus were used. English language, peer-reviewed papers published between 1970-April 2012 were considered for review. Criteria included Registered Nurses' communication during handovers in adult hospital settings. Twenty-nine papers were reviewed. The research lacks a clear conceptual framework to define the core purposes of Nurses' communication behaviours between shifts. Seven themes were identified: overall purpose; report givers and receivers; seeing the whole picture; teaching and education; language; patient-centred care; and social cohesion. Two main communication processes are required - one articulating the whole picture and the other detailing information about patients. This area of research is challenged by lack of consistency in terminology and methodological rigour. While recent research has confirmed the findings from the seminal work, it has not been able to elaborate on some of the key challenges to refine the knowledge base. A more integrated approach is required to understand the complex process of improving nursing communication behaviours, particularly around the nursing handover. A neglected area of study is the role of the unit lead in determining the communication standards of the whole nursing team. © 2013 John Wiley & Sons Ltd.

Spin-lattice relaxation times and knight shift in InSb and InAs

International Nuclear Information System (INIS)

Braun, P.; Grande, S.

1976-01-01

For a dominant contact interaction between nuclei and conduction electrons the relaxation rate is deduced. The extreme cases of degenerate and non-degenerate semiconductors are separately discussed. At strong degeneracy the product of the Knight shift and relaxation time gives the Korringa relation for metals. Measurements of the NMR spin-lattice relaxation times of 115 InSb and 115 InAs were made between 4.2 and 300 K for strongly degenerated samples. The different relaxation mechanisms are discussed and the experimental and theoretical results are compared. (author)

Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder.

Science.gov (United States)

Thurber, Kent R; Tycko, Robert

2009-01-01

Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of (79)Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determination of internal sample temperatures. Advantages of this method include high signal-to-noise, proximity of the (79)Br NMR frequency to that of (13)C, applicability from 20 K to 320 K or higher, and simultaneity with adjustment of the MAS axis direction. We show that spin-lattice relaxation in KBr is driven by a quadrupolar mechanism. We demonstrate a simple approach to including KBr powder in hydrated samples, such as biological membrane samples, hydrated amyloid fibrils, and hydrated microcrystalline proteins, that allows direct assessment of the effects of frictional and radio-frequency heating under experimentally relevant conditions.

Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

Science.gov (United States)

Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

2017-11-01

The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

Single memory with multiple shift register functionality

NARCIS (Netherlands)

2010-01-01

The present invention relates to a memory device comprising a memory (EM) having at least two predetermined register memory sections addressable by respective address ranges AS1-ASz) and at least one access port (P1-PZ) for providing access to said memory (EM). Furthermore, access control means (A)

Spin-Mechatronics

Science.gov (United States)

Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

2017-01-01

We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

Development of new neutron spin echo spectrometer using multi-layer film spin splitter

International Nuclear Information System (INIS)

Tasaki, Seiji; Ebisawa, Toru; Hino, Masahiro; Achiwa, Norio

2001-01-01

Neutron spin echo spectrometry is a method using neutron Larmor precession motion in magnetic field, for the measurement of velocity change before and after quasi-elastic scattering of neutron by a sample, such as macromolecules, with high accuracy. The neutron spin echo spectrometer is an interferometer in quantum mechanics, which a neutron is arranged with a parallel or an antiparallel state against magnetic field direction. Intensities of neutron interaction with matters are measured by the superposition of the both spin state components. The contrast losses of interference fringes caused from velocity diversion of incident neutrons are protected by spin echo method, in which a phase shift between the parallel and anti-parallel state neutrons is reduced by reversion of the spin state on the way of neutron path. Neutron beam of high intensity can be measured with a high energy resolution. Strong magnetic field is usually needed to introduce the phase shift between the both spin state components. A multi-layer film spin splitter (MSS) is developed for introducing the phase shift instead of the strong magnetic fields. The MSS consists of three layers, non-magnetic mirror of Ni/Ti, gap layer of Ti (∼1 μm), and magnetic mirror of Permalloy/Ge. Surface roughness of the gap layer leads to diversions of the phase shift, because that the fluctuation of thickness of gap layer is proportional to the phase shift. Characteristics of the MSS are tested as follow: (1) reflectivity of polarized neutron, (2) function check of the MSS, (3) uniformity check of the gap layer, (4) evaluation of the gap layer-thickness. (Suetake, M.)

Spin texture readout of a Moore-Read topological quantum register

NARCIS (Netherlands)

Romers, J.C.; Schoutens, K.

2012-01-01

We study the composite charged spin texture (CST) over the Moore-Read quantum Hall state that arises when a collection of elementary CSTs is moved to the same location. Following an algebraic approach based on the characteristic pair correlations of the Moore-Read state, we find that the spin

Quantized beam shifts in graphene

Energy Technology Data Exchange (ETDEWEB)

de Melo Kort-Kamp, Wilton Junior [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinitsyn, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego Alejandro Roberto [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-10-08

We predict the existence of quantized Imbert-Fedorov, Goos-Hanchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant α, while the Goos-Hanchen ones in multiples of α². We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.

pH-Dependent spin state population and 19F NMR chemical shift via remote ligand protonation in an iron(ii) complex.

Science.gov (United States)

Gaudette, Alexandra I; Thorarinsdottir, Agnes E; Harris, T David

2017-11-30

An Fe II complex that features a pH-dependent spin state population, by virtue of a variable ligand protonation state, is described. This behavior leads to a highly pH-dependent 19 F NMR chemical shift with a sensitivity of 13.9(5) ppm per pH unit at 37 °C, thereby demonstrating the potential utility of the complex as a 19 F chemical shift-based pH sensor.

Nature of the Darwin term and (Zα)4m3/M2 contribution to the Lamb shift for an arbitrary spin of the nucleus

International Nuclear Information System (INIS)

Khriplovich, I.B.; Milstein, A.I.; Sen'kov, R.A.

1997-01-01

The contact Darwin term is demonstrated to be of the same origin as the spin-orbit interaction. The (Zα) 4 m 3 /M 2 correction for the Lamb shift, generated by the Darwin term is found for an arbitrary nonvanishing spin of the nucleus, both half-integer and integer. There is also a contribution of the same nature to the nuclear quadrupole moment

Editorial: HOW THE CENTRE OF MALAYSIAN POLITICS SHIFTED TO THE ISLAMIST REGISTER 1969-2009

Directory of Open Access Journals (Sweden)

Editor Al-Jami'ah: Journal of Islamic Studies

2009-02-01

Full Text Available One of the most obvious observations that can be made about the form and content of Malaysian politics, political discourse and political culture today is how the country has shifted to a visibly more Islamist register, with the symbols and vocabulary of political Islam gaining prominence and visibility over the past four decades. This is particularly true in the case of Malaysia’s civil society space, which was once dominated by secular Non-Governmental Organisations (NGOs, mass movements and lobby groups. Today, however, we are looking at the relatively new phenomenon of a Malaysian civil society space which is increasingly being dominated by Islamist civil society movements that operate within the constitutional framework of the country but which are pushing for a clearly religious-communitarian agenda, namely the Islamisation of Malaysian society and politics. How did this come about?

Quantum cost optimized design of 4-bit reversible universal shift register using reduced number of logic gate

Science.gov (United States)

Maity, H.; Biswas, A.; Bhattacharjee, A. K.; Pal, A.

In this paper, we have proposed the design of quantum cost (QC) optimized 4-bit reversible universal shift register (RUSR) using reduced number of reversible logic gates. The proposed design is very useful in quantum computing due to its low QC, less no. of reversible logic gate and less delay. The QC, no. of gates, garbage outputs (GOs) are respectively 64, 8 and 16 for proposed work. The improvement of proposed work is also presented. The QC is 5.88% to 70.9% improved, no. of gate is 60% to 83.33% improved with compared to latest reported result.

Nature of the Darwin term and (Zα)4m3/M2 contribution to the Lamb shift for an arbitrary spin of the nucleus

International Nuclear Information System (INIS)

Khriplovich, I.B.; Mil'shtejn, A.I.; Sen'kov, R.A.

1996-01-01

The contact Darwin term is demonstrated to be of the same origin as the spin-orbit interactions. The (Zα) 4 m 3 /M 2 correction to the Lamb shift, generated by the Darwin term, is found for an arbitrary nonvanishing spin of the nucleus, both half-integer and integer. There is also a contribution of the same nature to the nuclear quadrupole moment [ru

Nature of the Darwin term and (Zα)4 m3/M2 contribution to the Lamb shift for an arbitrary spin of the nucleus

International Nuclear Information System (INIS)

Khriplovich, I.B.

1996-01-01

The contact Darwin term is demonstrated to be of the same origin as the spin-orbit interaction. The (Zα) 4 m 3 /M 2 correction to the Lamb shift, generated by the Darwin term, is found for an arbitrary nonvanishing spin of the nucleus, both half-integer and integer. There is also a contribution of the same nature to the nuclear quadrupole moment. (orig.)

Nature of the Darwin term and (Zα)4m3/M2 contribution to the Lamb shift for an arbitrary spin of a nucleus

International Nuclear Information System (INIS)

Khriplovich, I.B.; Milstein, A.I.; Sen'kov, R.A.

1997-01-01

The contact Darwin term is demonstrated to be of the same origin at the spin-orbit interaction. The (Zα) 4 m 3 /M 2 correction for the Lamb shift which is generated by the Darwin term, is found for an arbitrary nonvanishing spin of the nucleus, both half-integer and integer. There is also a contribution of the same nature to the nuclear quadrupole moment

1H, 13C and 13N chemical shifts and 1H-15N and 13C-15N heteronuclear spin-spin coupling constants n the NMR spectra of 5-substituted furfural oximes

International Nuclear Information System (INIS)

Popelis, Yu.Yu.; Liepin'sh, E.E.; Lukevits, E.Ya.

1986-01-01

The 1 H, 13 C, and 15 N NMR spectra of 15 N-enriched 5-substituted furfural oximes were investigated. It was shown that the chemical shifts of the ring atoms and the oxime group correlate satisfactorily with the F and R substituent constants, whereas their sensitivity to the effect of the substituents is lower than in monosubstituted furan derivatives. The constants of spin-spin coupling between the ring protons and the oxime group were determined. An analysis of the 1 H- 1 H spin-spin coupling constants (SSCC) on the basis of their stereospecificity indicates that the E isomers have primarily an s-trans conformation in polar dimethyl sulfoxide, whereas the Z isomers, on the other hand, have an s-cis conformation. The signs of the direct and geminal 13 C- 15 N SSCC were determined for 5-trimethylsilylfurfural oxime

Calculation of nuclear spin-spin coupling constants using frozen density embedding

Energy Technology Data Exchange (ETDEWEB)

Götz, Andreas W., E-mail: agoetz@sdsc.edu [San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Dr MC 0505, La Jolla, California 92093-0505 (United States); Autschbach, Jochen [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States); Visscher, Lucas, E-mail: visscher@chem.vu.nl [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

2014-03-14

We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects in the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.

Wavefunctions for topological quantum registers

International Nuclear Information System (INIS)

Ardonne, E.; Schoutens, K.

2007-01-01

We present explicit wavefunctions for quasi-hole excitations over a variety of non-abelian quantum Hall states: the Read-Rezayi states with k ≥ 3 clustering properties and a paired spin-singlet quantum Hall state. Quasi-holes over these states constitute a topological quantum register, which can be addressed by braiding quasi-holes. We obtain the braid properties by direct inspection of the quasi-hole wavefunctions. We establish that the braid properties for the paired spin-singlet state are those of 'Fibonacci anyons', and thus suitable for universal quantum computation. Our derivations in this paper rely on explicit computations in the parafermionic conformal field theories that underly these particular quantum Hall states

Double-spin-flip resonance of rhodium nuclei at positive and negative spin temperatures

DEFF Research Database (Denmark)

Tuoriniemi, J.T.; Knuuttila, T.A.; Lefmann, K.

2000-01-01

Sensitive SQUID-NMR measurements were used to study the mutual interactions in the highly polarized nuclear-spin system of rhodium metal. The dipolar coupling gives rise to a weak double-spin-flip resonance. The observed frequency shifts allow deducing separately the dipolarlike contribution...

Assignment of hyperfine shifted haem methyl carbon resonances in paramagnetic low-spin met-cyano complex of sperm whale myoglobin

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yasuhiko

1987-09-28

The hyperfine shifted resonances arising from all four individual haem carbons of the paramagnetic low-spin met-cyano complex of sperm whale myoglobin have been clearly identified and assigned for the first time with the aid of /sup 1/H-/sup 13/C heteronuclear chemical shift correlated spectroscopy. Alteration of the in-plane symmetry of the electronic structure of haem induced by the ligation of proximal histidyl imidazole spreads the haem carbon resonances to 32 ppm at 22/sup 0/C, indicating the sensitivity of those resonances to the haem electronic/molecular structure. Those resonances are potentially powerful probes in characterizing the nature of haem electronic structure. 25 refs.; 2 figs.; 1 table.

Quantum Computing with an Electron Spin Ensemble

DEFF Research Database (Denmark)

Wesenberg, Janus; Ardavan, A.; Briggs, G.A.D.

2009-01-01

We propose to encode a register of quantum bits in different collective electron spin wave excitations in a solid medium. Coupling to spins is enabled by locating them in the vicinity of a superconducting transmission line cavity, and making use of their strong collective coupling to the quantized...

Tuning the effective spin-orbit coupling in molecular semiconductors

KAUST Repository

Schott, Sam

2017-05-11

The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven difficult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high-mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g-shifts to spin-lattice relaxation times over four orders of magnitude, from 200 to 0.15 μs, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems.

Tuning the effective spin-orbit coupling in molecular semiconductors

KAUST Repository

Schott, Sam; McNellis, Erik R.; Nielsen, Christian B.; Chen, Hung-Yang; Watanabe, Shun; Tanaka, Hisaaki; McCulloch, Iain; Takimiya, Kazuo; Sinova, Jairo; Sirringhaus, Henning

2017-01-01

The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven difficult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high-mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g-shifts to spin-lattice relaxation times over four orders of magnitude, from 200 to 0.15 μs, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems.

Lamb shift and fine structure at n =2 in a hydrogenlike muonic atom with the nuclear spin I =0

Science.gov (United States)

Korzinin, Evgeny Yu.; Shelyuto, Valery A.; Ivanov, Vladimir G.; Karshenboim, Savely G.

2018-01-01

The paper is devoted to the Lamb shift and fine structure in a hydrogenlike muonic atom with a spinless nucleus up to the order α5m with all the recoil corrections included. Enhanced contributions of a higher order are also considered. We present the results on the pure QED contribution and on the finite-nuclear-size contribution, proportional to RN2, with the higher-order corrections included. We also consider the consistency of the pure QED theory and the evaluation of the nuclear-structure effects. Most of the QED theory is the same as the theory for the case of the nuclear spin 1/2. Additional nuclear-spin-dependent terms are considered in detail. The issue of the difference for the theories with a spinor nucleus and a scalar one is discussed for the recoil contributions in the order (Zα ) 4m ,α (Zα ) 4m , and (Zα ) 5m . The numerical results are presented for the muonic atoms with two lightest scalar nuclei, helium-4 and beryllium-10. We compare the theory of those muonic atoms with theory for the muonic hydrogen. Some higher-order finite-nuclear-size corrections for the Lamb shift in muonic hydrogen are revisited.

Electron spin resonance for the detection of long-range spin nematic order

Science.gov (United States)

Furuya, Shunsuke C.; Momoi, Tsutomu

2018-03-01

Spin nematic phase is a quantum magnetic phase characterized by a quadrupolar order parameter. Since the quadrupole operators are directly coupled to neither the magnetic field nor the neutron, currently, it is an important issue to develop a method for detecting the long-range spin nematic order. In this paper, we propose that electron spin resonance (ESR) measurements enable us to detect the long-range spin nematic order. We show that the frequency of the paramagnetic resonance peak in the ESR spectrum is shifted by the ferroquadrupolar order parameter together with other quantities. The ferroquadrupolar order parameter is extractable from the angular dependence of the frequency shift. In contrast, the antiferroquadrupolar order parameter is usually invisible in the frequency shift. Instead, the long-range antiferroquadrupolar order yields a characteristic resonance peak in the ESR spectrum, which we call a magnon-pair resonance peak. This resonance corresponds to the excitation of the bound magnon pair at the wave vector k =0 . Reflecting the condensation of bound magnon pairs, the field dependence of the magnon-pair resonance frequency shows a singular upturn at the saturation field. Moreover, the intensity of the magnon-pair resonance peak shows a characteristic angular dependence and it vanishes when the magnetic field is parallel to one of the axes that diagonalize the weak anisotropic interactions. We confirm these general properties of the magnon-pair resonance peak in the spin nematic phase by studying an S =1 bilinear-biquadratic model on the square lattice in the linear flavor-wave approximation. In addition, we argue applications to the S =1/2 frustrated ferromagnets and also the S =1/2 orthogonal dimer spin system SrCu2(BO3)2, both of which are candidate materials of spin nematics. Our theory for the antiferroquadrupolar ordered phase is consistent with many features of the magnon-pair resonance peak experimentally observed in the low

Quantum logic between remote quantum registers

Science.gov (United States)

Yao, N. Y.; Gong, Z.-X.; Laumann, C. R.; Bennett, S. D.; Duan, L.-M.; Lukin, M. D.; Jiang, L.; Gorshkov, A. V.

2013-02-01

We consider two approaches to dark-spin-mediated quantum computing in hybrid solid-state spin architectures. First, we review the notion of eigenmode-mediated unpolarized spin-chain state transfer and extend the analysis to various experimentally relevant imperfections: quenched disorder, dynamical decoherence, and uncompensated long-range coupling. In finite-length chains, the interplay between disorder-induced localization and decoherence yields a natural optimal channel fidelity, which we calculate. Long-range dipolar couplings induce a finite intrinsic lifetime for the mediating eigenmode; extensive numerical simulations of dipolar chains of lengths up to L=12 show remarkably high fidelity despite these decay processes. We further briefly consider the extension of the protocol to bosonic systems of coupled oscillators. Second, we introduce a quantum mirror based architecture for universal quantum computing that exploits all of the dark spins in the system as potential qubits. While this dramatically increases the number of qubits available, the composite operations required to manipulate dark-spin qubits significantly raise the error threshold for robust operation. Finally, we demonstrate that eigenmode-mediated state transfer can enable robust long-range logic between spatially separated nitrogen-vacancy registers in diamond; disorder-averaged numerics confirm that high-fidelity gates are achievable even in the presence of moderate disorder.

Survey of methods for rapid spin reversal

International Nuclear Information System (INIS)

McKibben, J.L.

1980-01-01

The need for rapid spin reversal technique in polarization experiments is discussed. The ground-state atomic-beam source equipped with two rf transitions for hydrogen can be reversed rapidly, and is now in use on several accelerators. It is the optimum choice provided the accelerator can accept H + ions. At present all rapid reversal experiments using H - ions are done with Lamb-shift sources; however, this is not a unique choice. Three methods for the reversal of the spin of the atomic beam within the Lamb-shift source are discussed in order of development. Coherent intensity and perhaps focus modulation seem to be the biggest problems in both types of sources. Methods for reducing these modulations in the Lamb-shift source are discussed. The same Lamb-shift apparatus is easily modified to provide information on the atomic physics of quenching of the 2S/sub 1/2/ states versus spin orientation, and this is also discussed. 2 figures

Chemical Shifts of the Carbohydrate Binding Domain of Galectin-3 from Magic Angle Spinning NMR and Hybrid Quantum Mechanics/Molecular Mechanics Calculations.

Science.gov (United States)

Kraus, Jodi; Gupta, Rupal; Yehl, Jenna; Lu, Manman; Case, David A; Gronenborn, Angela M; Akke, Mikael; Polenova, Tatyana

2018-03-22

Magic angle spinning NMR spectroscopy is uniquely suited to probe the structure and dynamics of insoluble proteins and protein assemblies at atomic resolution, with NMR chemical shifts containing rich information about biomolecular structure. Access to this information, however, is problematic, since accurate quantum mechanical calculation of chemical shifts in proteins remains challenging, particularly for 15 N H . Here we report on isotropic chemical shift predictions for the carbohydrate recognition domain of microcrystalline galectin-3, obtained from using hybrid quantum mechanics/molecular mechanics (QM/MM) calculations, implemented using an automated fragmentation approach, and using very high resolution (0.86 Å lactose-bound and 1.25 Å apo form) X-ray crystal structures. The resolution of the X-ray crystal structure used as an input into the AF-NMR program did not affect the accuracy of the chemical shift calculations to any significant extent. Excellent agreement between experimental and computed shifts is obtained for 13 C α , while larger scatter is observed for 15 N H chemical shifts, which are influenced to a greater extent by electrostatic interactions, hydrogen bonding, and solvation.

Control of the spin geometric phase in semiconductor quantum rings.

Science.gov (United States)

Nagasawa, Fumiya; Frustaglia, Diego; Saarikoski, Henri; Richter, Klaus; Nitta, Junsaku

2013-01-01

Since the formulation of the geometric phase by Berry, its relevance has been demonstrated in a large variety of physical systems. However, a geometric phase of the most fundamental spin-1/2 system, the electron spin, has not been observed directly and controlled independently from dynamical phases. Here we report experimental evidence on the manipulation of an electron spin through a purely geometric effect in an InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying an in-plane magnetic field, a phase shift of the Aharonov-Casher interference pattern towards the small spin-orbit-coupling regions is observed. A perturbation theory for a one-dimensional Rashba ring under small in-plane fields reveals that the phase shift originates exclusively from the modulation of a pure geometric-phase component of the electron spin beyond the adiabatic limit, independently from dynamical phases. The phase shift is well reproduced by implementing two independent approaches, that is, perturbation theory and non-perturbative transport simulations.

Strong spin-photon coupling in silicon

Science.gov (United States)

Samkharadze, N.; Zheng, G.; Kalhor, N.; Brousse, D.; Sammak, A.; Mendes, U. C.; Blais, A.; Scappucci, G.; Vandersypen, L. M. K.

2018-03-01

Long coherence times of single spins in silicon quantum dots make these systems highly attractive for quantum computation, but how to scale up spin qubit systems remains an open question. As a first step to address this issue, we demonstrate the strong coupling of a single electron spin and a single microwave photon. The electron spin is trapped in a silicon double quantum dot, and the microwave photon is stored in an on-chip high-impedance superconducting resonator. The electric field component of the cavity photon couples directly to the charge dipole of the electron in the double dot, and indirectly to the electron spin, through a strong local magnetic field gradient from a nearby micromagnet. Our results provide a route to realizing large networks of quantum dot–based spin qubit registers.

Accelerating proton spin diffusion in perdeuterated proteins at 100 kHz MAS

Energy Technology Data Exchange (ETDEWEB)

Wittmann, Johannes J.; Agarwal, Vipin; Hellwagner, Johannes; Lends, Alons; Cadalbert, Riccardo; Meier, Beat H., E-mail: beme@ethz.ch; Ernst, Matthias, E-mail: maer@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland)

2016-12-15

Fast magic-angle spinning (>60 kHz) has many advantages but makes spin-diffusion-type proton–proton long-range polarization transfer inefficient and highly dependent on chemical-shift offset. Using 100%-HN-[{sup 2}H,{sup 13}C,{sup 15}N]-ubiquitin as a model substance, we quantify the influence of the chemical-shift difference on the spin diffusion between proton spins and compare two experiments which lead to an improved chemical-shift compensation of the transfer: rotating-frame spin diffusion and a new experiment, reverse amplitude-modulated MIRROR. Both approaches enable broadband spin diffusion, but the application of the first variant is limited due to fast spin relaxation in the rotating frame. The reverse MIRROR experiment, in contrast, is a promising candidate for the determination of structurally relevant distance restraints. The applied tailored rf-irradiation schemes allow full control over the range of recoupled chemical shifts and efficiently drive spin diffusion. Here, the relevant relaxation time is the larger longitudinal relaxation time, which leads to a higher signal-to-noise ratio in the spectra.

Quantum Spin Lenses in Atomic Arrays

Directory of Open Access Journals (Sweden)

A. W. Glaetzle

2017-09-01

Full Text Available We propose and discuss quantum spin lenses, where quantum states of delocalized spin excitations in an atomic medium are focused in space in a coherent quantum process down to (essentially single atoms. These can be employed to create controlled interactions in a quantum light-matter interface, where photonic qubits stored in an atomic ensemble are mapped to a quantum register represented by single atoms. We propose Hamiltonians for quantum spin lenses as inhomogeneous spin models on lattices, which can be realized with Rydberg atoms in 1D, 2D, and 3D, and with strings of trapped ions. We discuss both linear and nonlinear quantum spin lenses: in a nonlinear lens, repulsive spin-spin interactions lead to focusing dynamics conditional to the number of spin excitations. This allows the mapping of quantum superpositions of delocalized spin excitations to superpositions of spatial spin patterns, which can be addressed by light fields and manipulated. Finally, we propose multifocal quantum spin lenses as a way to generate and distribute entanglement between distant atoms in an atomic lattice array.

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

Staff perceptions of leadership during implementation of task-shifting in three surgical units.

Science.gov (United States)

Henderson, Amanda; Paterson, Karyn; Burmeister, Liz; Thomson, Bernadette; Young, Louise

2013-03-01

Registered nurses are difficult to recruit and retain. Task shifting, which involves reallocation of delegation, can reduce demand for registered nurses. Effective leadership is needed for successful task shifting. This study explored leadership styles of three surgical nurse unit managers. Staff completed surveys before and after the implementation of task shifting. Task shifting involved the introduction of endorsed enrolled nurses (licensed nurses who must practise under registered nurse supervision) to better utilize registered nurses. Implementation of task shifting occurred over 4 months in a 700-bed tertiary hospital, in southeast Queensland, Australia. A facilitator assisted nurse unit managers during implementation. The impact was assessed by comparison of data before (n = 49) and after (n = 72) task shifting from registered nurses and endorsed enrolled nurses (n = 121) who completed the Ward Organization Features Survey. Significant differences in leadership and staff organization subscales across the settings suggest that how change involving task shifting is implemented influences nurses' opinions of leadership. Leadership behaviours of nurse unit managers is a key consideration in managing change such as task shifting. Consistent and clear messages from leaders about practice change are viewed positively by nursing staff. In the short term, incremental change possibly results in staff maintaining confidence in leadership. © 2012 Blackwell Publishing Ltd.

Towards a Room-Temperature Spin Quantum Bus in Diamond via Electron Photoionization, Transport, and Capture

Directory of Open Access Journals (Sweden)

M. W. Doherty

2016-11-01

Full Text Available Diamond is a proven solid-state platform for spin-based quantum technology. The nitrogen-vacancy center in diamond has been used to realize small-scale quantum information processing and quantum sensing under ambient conditions. A major barrier in the development of large-scale quantum information processing in diamond is the connection of nitrogen-vacancy spin registers by a quantum bus at room temperature. Given that diamond is expected to be an ideal spin transport material, the coherent transport of spin directly between the spin registers offers a potential solution. Yet, there has been no demonstration of spin transport in diamond due to difficulties in achieving spin injection and detection via conventional methods. Here, we exploit detailed knowledge of the paramagnetic defects in diamond to identify novel mechanisms to photoionize, transport, and capture spin-polarized electrons in diamond at room temperature. Having identified these mechanisms, we explore how they may be combined to realize an on-chip spin quantum bus.

Graphene spin valve: An angle sensor

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

2017-06-15

Graphene spin valves can be optimized for various spintronic applications by tuning the associated experimental parameters. In this work, we report the angle dependent magnetoresistance (MR) in graphene spin valve for different orientations of applied magnetic field (B). The switching points of spin valve signals show a clear shift towards higher B for each increasing angle of the applied field, thus sensing the response for respective orientation of the magnetic field. The angular variation of B shifts the switching points from ±95 G to ±925 G as the angle is varied from 0° to 90° at 300 K. The observed shifts in switching points become more pronounced (±165 G to ±1450 G) at 4.2 K for similar orientation. A monotonic increase in MR ratio is observed as the angle of magnetic field is varied in the vertical direction at 300 K and 4.2 K temperatures. This variation of B (from 0° to 90°) increases the magnitude of MR ratio from ∼0.08% to ∼0.14% at 300 K, while at 4.2 K it progresses to ∼0.39% from ∼0.14%. The sensitivity related to angular variation of such spin valve structure can be employed for angle sensing applications.

Spin in the Media - the Media in a (self-Spin?

Directory of Open Access Journals (Sweden)

Nete Nørgaard Kristensen

2006-09-01

Full Text Available The article focuses on the discussion of spin in the Danish media, especially during the 2005 election campaign, in which spin was a prominent issue amongst journalists. The main argument is that this is not primarily an expression of a professional, self-reflective con- sciousness regarding the shifts in the relationship between the media, society and politics. Rather, it is an expression of a self-legitimizing meta-discourse that might, however, fail to see the more structurally rooted tendencies that spin is part of - a mediatization of politics - presenting new perspectives and challenges for both politics and the media. These perspectives appear to disintegrate in the comprehen- sive but often one-dimensional and self-centered discourse of jour- nalists and communication experts, wherein they proclaim every political, communicative initiative as spin in the hunt for the disclosure of political facade.

Spin Hall effect of a light beam in left-handed materials

International Nuclear Information System (INIS)

Luo Hailu; Wen Shuangchun; Shu Weixing; Tang Zhixiang; Zou Yanhong; Fan Dianyuan

2009-01-01

We establish a general propagation model to describe the spin Hall effect of light beam in left-handed materials (LHMs). A spin-dependent shift of the beam centroid perpendicular to the refractive index gradient for the light beam through an air-LHM interface is demonstrated. For a certain circularly polarized component, whether the transverse shift is positive or negative depends on the magnitude of the refractive index gradient. Very surprisingly, the spin Hall effect in the LHM is unreversed, although the sign of refractive index gradient is reversed. The physics underlying this counterintuitive effect is that the spin angular momentum of photons is unreversed. Further, we reveal that the angular shift in the LHM is reversed due to the negative diffraction. These findings provide alternative evidence for that the linear momentum of photons is reversed, while the spin angular momentum is unreversed in the LHM.

Measurement of the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering

International Nuclear Information System (INIS)

Stuart, S.J.

1982-08-01

The experimental procedures and methods of data analysis used to measure the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering at thirteen different energies in the range 300 to 800 MeV are presented. The results compare favorably with previous data. Good agreement is found with phase shift predictions at energies below 500 MeV

S, P, D, F, G-waves KN phase shifts in a constituent quark model with a spin-orbit interaction

International Nuclear Information System (INIS)

Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

2002-01-01

The I=1 and I=0 kaon-nucleon s, p, d, f, g-waves phase shifts have been calculated in a nonrelativistic quark potential model using the resonating group method (RGM). The interquark potential includes gluon exchanges with a spin-orbit interaction. This force has been determined to reproduce as well as possible the meson and baryon spectra. The same force is employed for the cluster and intercluster dynamics and the relative KN wave-function is calculated without any approximation. While some channels are correctly described, the theory is still unable to explain others

Electron Spin Resonance Shift and Linewidth Broadening of Nitrogen-Vacancy Centers in Diamond as a Function of Electron Irradiation Dose

OpenAIRE

Kim, Edwin; Acosta, Victor M.; Bauch, Erik; Budker, Dmitry; Hemmer, Philip R.

2009-01-01

A high-nitrogen-concentration diamond sample was subject to 200-keV electron irradiation using a transmission electron microscope. The optical and spin-resonance properties of the nitrogen-vacancy (NV) color centers were investigated as a function of the irradiation dose up to 6.4\\times1021 e-/cm2. The microwave transition frequency of the NV- center was found to shift by up to 0.6% (17.1 MHz) and the linewidth broadened with increasing electron-irradiation dose. Unexpectedly, the measured ma...

Lanthanide shift reagents, binding, shift mechanisms and exchange

International Nuclear Information System (INIS)

Boer, J.W.M. de

1977-01-01

Paramagnetic lanthanide shift reagents, when added to a solution of a substrate, induce shifts in the nuclear magnetic resonance (NMR) spectrum of the substrate molecules. The induced shifts contain information about the structure of the shift reagent substrate complex. The structural information, however, may be difficult to extract because of the following effects: (1) different complexes between shift reagent and substrate may be present in solution, e.g. 1:1 and 1:2 complexes, and the shift observed is a weighed average of the shifts of the substrate nuclei in the different complexes; (2) the Fermi contact interaction, arising from the spin density at the nucleus, contributes to the induced shift; (3) chemical exchange effects may complicate the NMR spectrum. In this thesis, the results of an investigation into the influence of these effects on the NMR spectra of solutions containing a substrate and LSR are presented. The equations describing the pseudo contact and the Fermi contact shift are derived. In addition, it is shown how the modified Bloch equations describing the effect of the chemical exchange processes occurring in the systems studied can be reduced to the familiar equations for a two-site exchange case. The binding of mono- and bifunctional ethers to the shift reagent are reported. An analysis of the induced shifts is given. Finally, the results of the experiments performed to study the exchange behavior of dimethoxyethane and heptafluorodimethyloctanedionato ligands are presented

Possible evidence for spin-transfer torque induced by spin-triplet supercurrent

KAUST Repository

Li, Lailai

2017-10-04

Cooper pairs in superconductors are normally spin singlet. Nevertheless, recent studies suggest that spin-triplet Cooper pairs can be created at carefully engineered superconductor-ferromagnet interfaces. If Cooper pairs are spin-polarized they would transport not only charge but also a net spin component, but without dissipation, and therefore minimize the heating effects associated with spintronic devices. Although it is now established that triplet supercurrents exist, their most interesting property - spin - is only inferred indirectly from transport measurements. In conventional spintronics, it is well known that spin currents generate spin-transfer torques that alter magnetization dynamics and switch magnetic moments. The observation of similar effects due to spin-triplet supercurrents would not only confirm the net spin of triplet pairs but also pave the way for applications of superconducting spintronics. Here, we present a possible evidence for spin-transfer torques induced by triplet supercurrents in superconductor/ferromagnet/superconductor (S/F/S) Josephson junctions. Below the superconducting transition temperature T_c, the ferromagnetic resonance (FMR) field at X-band (~ 9.0 GHz) shifts rapidly to a lower field with decreasing temperature due to the spin-transfer torques induced by triplet supercurrents. In contrast, this phenomenon is absent in ferromagnet/superconductor (F/S) bilayers and superconductor/insulator/ferromagnet/superconductor (S/I/F/S) multilayers where no supercurrents pass through the ferromagnetic layer. These experimental observations are discussed with theoretical predictions for ferromagnetic Josephson junctions with precessing magnetization.

Driving spin transition at interface: Role of adsorption configurations

Science.gov (United States)

Zhang, Yachao

2018-01-01

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

Spin tune dependence on closed orbit in RHIC

International Nuclear Information System (INIS)

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

2010-01-01

Polarized proton beams are accelerated in RHIC to 250 GeV energy with the help of Siberian Snakes. The pair of Siberian Snakes in each RHIC ring holds the design spin tune at 1/2 to avoid polarization loss during acceleration. However, in the presence of closed orbit errors, the actual spin tune can be shifted away from the exact 1/2 value. It leads to a corresponding shift of locations of higher-order ('snake') resonances and limits the available betatron tune space. The largest closed orbit effect on the spin tune comes from the horizontal orbit angle between the two snakes. During RHIC Run in 2009 dedicated measurements with polarized proton beams were taken to verify the dependence of the spin tune on the local orbits at the Snakes. The experimental results are presented along with the comparison with analytical predictions.

On The Designed And Constructed Feedback Shift-Register Encoder

African Journals Online (AJOL)

An encoder capable of cyclical shifting of data, and which can therefore be used for Bose-Chaudhuri and Hocquenghem (BCH) coding, has been designed and constructed using discrete components. It comprises basically four bistable multivibrators and an exclusive-OR device. On completion, the encoder performed ...

NMR studies of spin dynamics in cuprates

International Nuclear Information System (INIS)

Takigawa, M.; Mitzi, D.B.

1994-01-01

The authors report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi 2.1 Sr 1.94 Ca 0.88 Cu 2.07 O 8+σ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa 2 Cu 3 O 6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector

NMR studies of spin dynamics in cuprates

Science.gov (United States)

Takigawa, M.; Mitzi, D. B.

1994-04-01

We report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi2.1Sr1.94Ca0.88Cu2.07O8+δ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa2Cu3O6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector.

Chains of phase-shift ambiguities in elastic spin-0-spin-1/2 scattering

International Nuclear Information System (INIS)

Berends, F.A.; Reisen, J.C.J.M. van

1977-01-01

It is shown, that a previously constructed phase-shift ambiguity for an arbitrary number, 2L + 1, of partial waves can be connected to L - 1 other ambiguities. The two sets of phase shifts defined by the chain of ambiguities become equal (modulo π) at the endpoints of the chain, but in general not at the endpoints of the ambiguities. Also other examples of such chains are given. (Auth.)

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.

Spin-flip scattering effect on the current-induced spin torque in ferromagnet-insulator-ferromagnet tunnel junctions

International Nuclear Information System (INIS)

Zhu Zhengang; Su Gang; Jin Biao; Zheng Qingrong

2003-01-01

We have investigated the current-induced spin transfer torque of a ferromagnet-insulator-ferromagnet tunnel junction by taking the spin-flip scatterings into account. It is found that the spin-flip scattering can induce an additional spin torque, enhancing the maximum of the spin torque and giving rise to an angular shift compared to the case when the spin-flip scatterings are neglected. The effects of the molecular fields of the left and right ferromagnets on the spin torque are also studied. It is found that τ Rx /I e (τ Rx is the spin-transfer torque acting on the right ferromagnet and I e is the tunneling electrical current) does vary with the molecular fields. At two certain angles, τ Rx /I e is independent of the molecular field of the right ferromagnet, resulting in two crossing points in the curve of τ Rx /I e versus the relevant orientation for different molecular fields

On The Designed And Constructed Feedback Shift-Register Encoder

African Journals Online (AJOL)

Information transmission in noisy channels can be achieved with vanishingly small probability of error by proper coding of the information as long as the encoding rate is less than the channel capacity. An encoder capable of cyclical shifting of data, and which can therefore be used for Bose-Chaudhuri and Hocquenghem ...

PSYCHE Pure Shift NMR Spectroscopy.

Science.gov (United States)

Foroozandeh, Mohammadali; Morris, Gareth; Nilsson, Mathias

2018-03-13

Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Associations of rotational shift work and night shift status with hypertension: a systematic review and meta-analysis.

Science.gov (United States)

Manohar, Sandhya; Thongprayoon, Charat; Cheungpasitporn, Wisit; Mao, Michael A; Herrmann, Sandra M

2017-10-01

The reported risks of hypertension (HTN) in rotating shift and night shift workers are controversial. The objective of this meta-analysis was to assess the association between shift work status and HTN. A literature search was performed using MEDLINE, EMBASE and Cochrane Database from inception through October 2016. Studies that reported odds ratios (OR) comparing the risk of HTN in shift workers were included. A prespecified subgroup analysis by rotating shift and night shift statuses were also performed. Pooled OR and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method. The protocol for this study is registered with International Prospective Register of Systematic Reviews; no. CRD42016051843. Twenty-seven observational studies (nine cohort and 18 cross-sectional studies) with a total of 394 793 individuals were enrolled. The pooled ORs of HTN in shift workers in cohort and cross-sectional studies were 1.31 (95% CI, 1.07-1.60) and 1.10 (95% CI, 1.00-1.20), respectively. When meta-analysis was restricted only to cohort studies in rotating shift, the pooled OR of HTN in rotating shift workers was 1.34 (95% CI, 1.08-1.67). The data regarding night shift and HTN in cohort studies was limited. The pooled OR of HTN in night shift workers in cross-sectional studies was 1.07 (95% CI, 0.85-1.35). Based on the findings of our meta-analysis, shiftwork status may play an important role in HTN, as there is a significant association between rotating shift work and HTN. However, there is no significant association between night shift status and risk of HTN.

Spin-Hall conductivity and electric polarization in metallic thin films

KAUST Repository

Wang, Xuhui

2013-02-21

We predict theoretically that when a normal metallic thin film (without bulk spin-orbit coupling, such as Cu or Al) is sandwiched by two insulators, two prominent effects arise due to the interfacial spin-orbit coupling: a giant spin-Hall conductivity due to the surface scattering and a transverse electric polarization due to the spin-dependent phase shift in the spinor wave functions.

Spin-Hall conductivity and electric polarization in metallic thin films

KAUST Repository

Wang, Xuhui; Xiao, Jiang; Manchon, Aurelien; Maekawa, Sadamichi

2013-01-01

We predict theoretically that when a normal metallic thin film (without bulk spin-orbit coupling, such as Cu or Al) is sandwiched by two insulators, two prominent effects arise due to the interfacial spin-orbit coupling: a giant spin-Hall conductivity due to the surface scattering and a transverse electric polarization due to the spin-dependent phase shift in the spinor wave functions.

Detecting the multi-spin interaction of an XY spin chain by the geometric phase of a coupled qubit

International Nuclear Information System (INIS)

Zhang, Xiu-xing; Zhang, Ai-ping; Li, Fu-li

2012-01-01

We investigate geometric phase (GP) of a qubit symmetrically coupled to a XY spin chain with three-spin interaction in a transverse magnetic field. An analytical expression for the GP is found in the weak coupling limit. It is shown that the GP displays a sharp peak or dip around the quantum phase transition point of the spin chain. Without the three-spin interaction, the GP has a peak or dip around the critical point λ=1. If the three-spin interaction exists, the peak or dip position is obviously shifted away from the original position. This result reveals that the GP may be taken as an observable to detect both the existence and strength of multi-spin interaction in a spin chain. -- Highlights: ► Analytical expression for geometric phase (GP) of a qubit coupled to a spin chain is obtained. ► Relation between GP and multi-spin interaction is investigated. ► Detection of multi-spin interaction by means of GP is proposed.

Effects of marital status and shift work on family function among registered nurses.

Science.gov (United States)

Tai, Shu-Yu; Lin, Pei-Chen; Chen, Yao-Mei; Hung, Hsin-Chia; Pan, Chih-Hong; Pan, Shung-Mei; Lee, Chung-Yin; Huang, Chia-Tsuan; Wu, Ming-Tsang

2014-01-01

This study aims to assess the interactive effect of marital status and shift work on family function. A population-based sample of 1,438 nurses between the ages of 20-45 yr was recruited from Taiwan during the period from July 2005 to April 2006 using a mailed questionnaire. The self-administered questionnaire contained information about demographic data, work status, shift work schedule, and the Family APGAR (Adaptation, Partnership, Growth, Affection, and Resolve) Scale, to evaluate family function. Compared to day shift nurses, non-night and rotation shift nurses had 1.53- and 1.38-fold (95% CI=1.09-2.14 and 1.01-1.88) risk to have poor family function after adjusting for other covariates. Married nurses, by contrast, had a 0.44-fold (95% CI=0.29-0.66) risk to have poor family function compared to single nurses. In addition, married nurses who worked non-night or rotation shifts had a significantly higher percent of poor family function than those married nurses working day shifts; however, similar results were not replicated in single nurses. We concluded that shift work and marital status could influence family function.

Effects of Marital Status and Shift Work on Family Function among Registered Nurses

Science.gov (United States)

TAI, Shu-Yu; LIN, Pei-Chen; CHEN, Yao-Mei; HUNG, Hsin-Chia; PAN, Chih-Hong; PAN, Shung-Mei; LEE, Chung-Yin; HUANG, Chia-Tsuan; WU, Ming-Tsang

2014-01-01

This study aims to assess the interactive effect of marital status and shift work on family function. A population-based sample of 1,438 nurses between the ages of 20–45 yr was recruited from Taiwan during the period from July 2005 to April 2006 using a mailed questionnaire. The self-administered questionnaire contained information about demographic data, work status, shift work schedule, and the Family APGAR (Adaptation, Partnership, Growth, Affection, and Resolve) Scale, to evaluate family function. Compared to day shift nurses, non-night and rotation shift nurses had 1.53- and 1.38-fold (95% CI=1.09–2.14 and 1.01–1.88) risk to have poor family function after adjusting for other covariates. Married nurses, by contrast, had a 0.44-fold (95% CI=0.29–0.66) risk to have poor family function compared to single nurses. In addition, married nurses who worked non-night or rotation shifts had a significantly higher percent of poor family function than those married nurses working day shifts; however, similar results were not replicated in single nurses. We concluded that shift work and marital status could influence family function. PMID:24909112

Lorentz transformations, sideways shift and massless spinning particles

Science.gov (United States)

Bolonek-Lasoń, K.; Kosiński, P.; Maślanka, P.

2017-06-01

Recently (Stone et al. (2015) [16]) the influence of the so called ;Wigner translations; (more generally-Lorentz transformations) on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation) has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

Lorentz transformations, sideways shift and massless spinning particles

Directory of Open Access Journals (Sweden)

K. Bolonek-Lasoń

2017-06-01

Full Text Available Recently (Stone et al. (2015 [16] the influence of the so called “Wigner translations” (more generally-Lorentz transformations on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

Lorentz transformations, sideways shift and massless spinning particles

Energy Technology Data Exchange (ETDEWEB)

Bolonek-Lasoń, K. [Department of Statistical Methods, Faculty of Economics and Sociology (Poland); Kosiński, P. [Department of Computer Science, Faculty of Physics and Applied Informatics, University of Łódź, Pomorska 149/153, 90-236 Łódź (Poland); Maślanka, P., E-mail: pmaslan@uni.lodz.pl [Department of Computer Science, Faculty of Physics and Applied Informatics, University of Łódź, Pomorska 149/153, 90-236 Łódź (Poland)

2017-06-10

Recently (Stone et al. (2015) ) the influence of the so called “Wigner translations” (more generally-Lorentz transformations) on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation) has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

Magic Angle Spinning NMR Structure Determination of Proteins from Pseudocontact Shifts

KAUST Repository

Li, Jianping

2013-06-05

Magic angle spinning solid-state NMR is a unique technique to study atomic-resolution structure of biomacromolecules which resist crystallization or are too large to study by solution NMR techniques. However, difficulties in obtaining sufficient number of long-range distance restraints using dipolar coupling based spectra hamper the process of structure determination of proteins in solid-state NMR. In this study it is shown that high-resolution structure of proteins in solid phase can be determined without the use of traditional dipolar-dipolar coupling based distance restraints by combining the measurements of pseudocontact shifts (PCSs) with Rosetta calculations. The PCSs were generated by chelating exogenous paramagnetic metal ions to a tag 4-mercaptomethyl-dipicolinic acid, which is covalently attached to different residue sites in a 56-residue immunoglobulin-binding domain of protein G (GB1). The long-range structural restraints with metal-nucleus distance of up to ∼20 Å are quantitatively extracted from experimentally observed PCSs, and these are in good agreement with the distances back-calculated using an X-ray structure model. Moreover, we demonstrate that using several paramagnetic ions with varied paramagnetic susceptibilities as well as the introduction of paramagnetic labels at different sites can dramatically increase the number of long-range restraints and cover different regions of the protein. The structure generated from solid-state NMR PCSs restraints combined with Rosetta calculations has 0.7 Å root-mean-square deviation relative to X-ray structure. © 2013 American Chemical Society.

Magic Angle Spinning NMR Structure Determination of Proteins from Pseudocontact Shifts

KAUST Repository

Li, Jianping; Pilla, Kala Bharath; Li, Qingfeng; Zhang, Zhengfeng; Su, Xuncheng; Huber, Thomas; Yang, Jun

2013-01-01

Magic angle spinning solid-state NMR is a unique technique to study atomic-resolution structure of biomacromolecules which resist crystallization or are too large to study by solution NMR techniques. However, difficulties in obtaining sufficient number of long-range distance restraints using dipolar coupling based spectra hamper the process of structure determination of proteins in solid-state NMR. In this study it is shown that high-resolution structure of proteins in solid phase can be determined without the use of traditional dipolar-dipolar coupling based distance restraints by combining the measurements of pseudocontact shifts (PCSs) with Rosetta calculations. The PCSs were generated by chelating exogenous paramagnetic metal ions to a tag 4-mercaptomethyl-dipicolinic acid, which is covalently attached to different residue sites in a 56-residue immunoglobulin-binding domain of protein G (GB1). The long-range structural restraints with metal-nucleus distance of up to ∼20 Å are quantitatively extracted from experimentally observed PCSs, and these are in good agreement with the distances back-calculated using an X-ray structure model. Moreover, we demonstrate that using several paramagnetic ions with varied paramagnetic susceptibilities as well as the introduction of paramagnetic labels at different sites can dramatically increase the number of long-range restraints and cover different regions of the protein. The structure generated from solid-state NMR PCSs restraints combined with Rosetta calculations has 0.7 Å root-mean-square deviation relative to X-ray structure. © 2013 American Chemical Society.

Spin-locking and cross-polarization under magic-angle spinning of uniformly labeled solids.

Science.gov (United States)

Hung, Ivan; Gan, Zhehong

2015-07-01

Spin-locking and cross-polarization under magic-angle spinning are investigated for uniformly (13)C and (15)N labeled solids. In particular, the interferences from chemical shift anisotropy, and (1)H heteronuclear and (13)C homonuclear dipolar couplings are identified. The physical origin of these interferences provides guidelines for selecting the best (13)C and (15)N polarization transfer rf fields. Optimal settings for both the zero- and double-quantum cross-polarization transfer mechanisms are recommended. Copyright © 2015 Elsevier Inc. All rights reserved.

Magnetic pseudo-fields in a rotating electron-nuclear spin system

Science.gov (United States)

Wood, A. A.; Lilette, E.; Fein, Y. Y.; Perunicic, V. S.; Hollenberg, L. C. L.; Scholten, R. E.; Martin, A. M.

2017-11-01

Analogous to the precession of a Foucault pendulum observed on the rotating Earth, a precessing spin observed in a rotating frame of reference appears frequency-shifted. This can be understood as arising from a magnetic pseudo-field in the rotating frame that nevertheless has physically significant consequences, such as the Barnett effect. To detect these pseudo-fields, a rotating-frame sensor is required. Here we use quantum sensors, nitrogen-vacancy (NV) centres, in a rapidly rotating diamond to detect pseudo-fields in the rotating frame. Whereas conventional magnetic fields induce precession at a rate proportional to the gyromagnetic ratio, rotation shifts the precession of all spins equally, and thus primarily affect 13C nuclear spins in the sample. We are thus able to explore these effects via quantum sensing in a rapidly rotating frame, and define a new approach to quantum control using rotationally induced nuclear spin-selective magnetic fields. This work provides an integral step towards realizing precision rotation sensing and quantum spin gyroscopes.

Alternating spin chain compound AgVOAsO4 probed by 75As NMR

Science.gov (United States)

Ahmed, N.; Khuntia, P.; Ranjith, K. M.; Rosner, H.; Baenitz, M.; Tsirlin, A. A.; Nath, R.

2017-12-01

75As NMR measurements were performed on a polycrystalline sample of spin-1/2 alternating spin chain Heisenberg antiferromagnet AgVOAsO4. The temperature-dependent NMR shift K (T ) , which is a direct measure of the intrinsic spin susceptibility, agrees very well with the spin-1/2 alternating-chain model, justifying the assignment of the spin lattice. From the analysis of K (T ) , magnetic exchange parameters were estimated as follows: the leading exchange J /kB≃38.4 K and the alternation ratio α =J'/J ≃0.69 . The transferred hyperfine coupling between the 75As nucleus and V4 + spins obtained by comparing the NMR shift with the bulk susceptibility amounts to Ahf≃3.3 TμB. The effect of interchain couplings on the low-temperature activated behavior of K (T ) and the spin-lattice relaxation rate 1 /T1 is identified.

Linear Hyperfine Tuning of Donor Spins in Silicon Using Hydrostatic Strain

Science.gov (United States)

Mansir, J.; Conti, P.; Zeng, Z.; Pla, J. J.; Bertet, P.; Swift, M. W.; Van de Walle, C. G.; Thewalt, M. L. W.; Sklenard, B.; Niquet, Y. M.; Morton, J. J. L.

2018-04-01

We experimentally study the coupling of group V donor spins in silicon to mechanical strain, and measure strain-induced frequency shifts that are linear in strain, in contrast to the quadratic dependence predicted by the valley repopulation model (VRM), and therefore orders of magnitude greater than that predicted by the VRM for small strains |ɛ |hydrostatic component of strain and achieve semiquantitative agreement with the experimental values. Our results provide a framework for making quantitative predictions of donor spins in silicon nanostructures, such as those being used to develop silicon-based quantum processors and memories. The strong spin-strain coupling we measure (up to 150 GHz per strain, for Bi donors in Si) offers a method for donor spin tuning—shifting Bi donor electron spins by over a linewidth with a hydrostatic strain of order 10-6—as well as opportunities for coupling to mechanical resonators.

Spin-directed momentum transfers in SIDIS baryon production

International Nuclear Information System (INIS)

Sivers, D.

2016-01-01

The measurement of transverse single-spin asymmetries for baryon production in the target fragmentation region of semi-inclusive deep-inelastic scattering (SIDIS), can produce important insight into those nonperturbative aspects of QCD directly associated with confinement and with the dynamical breaking of chiral symmetry. We discuss here, in terms of spin-directed momentum transfers, the powerful quantum field- theoretical constraints on the spin-orbit dynamics underlying these transverse spin observables. The A τ -odd spin-directed momentum shifts, originating either in the target nucleon (δk TN ) or in the QCD jets (δp TN ) produced in the deep inelastic scattering process, represent significant quantum entanglement effects connecting information from current fragmentation with observables in target fragmentation. (author)

Depolarization of neutron spin echo by magnetic fluid

International Nuclear Information System (INIS)

Achiwa, N.; Sirozu, G.; Nishioka, T.; Ebisawa, T.; Hino, M.; Tasaki, S.; Kawai, T.; Yamazaki, D.

2001-01-01

A new method to study the fluctuations of magnetization in magnetic fluids by measuring relations between the phase shift of Larmor precession and the visibility of the neutron spin echo caused by the change of flight path length is studied. Magnetic fluid in which fine particles of magnetite of about 10 nm diameters coated with oleic acid and suspended in water was used. Thickness of the sample was 2 mm. In the dynamics of magnetic fluids, Brownian motions of colloids and the thermal fluctuations of magnetization known as the superparamagnetism are dominant. Isolated ferromagnetic particles of the present size are superparamagnetic but they aggregate to form clusters in a weak magnetic field in the sample of 40% weight density. When neutrons pass the sample, spins process in the magnetic flux density of the clusters fluctuating in time and space. Consequently the Larmor precession phases become distributed and the quantization axes are fluctuated. The result is observed as a decrease of the visibility of the spin echo signals. The change of magnetic flux density in the magnetic fluid is measured from the change of echo visibility of the neutrons, vice versa. In the present experiment, echo was measured at q=0. It is observed that the phase shift changes as a quadratic function of the sample angle reflecting the change of the path length through the sample. Since the number of Larmor precession is proportional to the product of the magnetic field and the length of the flight path, mean flux density in the magnetic fluid is calculated from the phase shift. On the other hand, the decrease of the spin echo amplitude as the function of the sample angle reflects the time and space fluctuations of the flux density in the sample. If the direction of the magnetic flux density vector (quantization axis) changes slowly enough compared to the Larmor precession period while a neutron passes one magnetic domain, the neutron spin rotation in the domain is given by the spin

Information-flux approach to multiple-spin dynamics

International Nuclear Information System (INIS)

Di Franco, C.; Paternostro, M.; Kim, M. S.; Palma, G. M.

2007-01-01

We introduce and formalize the concept of information flux in a many-body register as the influence that the dynamics of a specific element receive from any other element of the register. By quantifying the information flux in a protocol, we can design the most appropriate initial state of the system and, noticeably, the distribution of coupling strengths among the parts of the register itself. The intuitive nature of this tool and its flexibility, which allow for easily manageable numerical approaches when analytic expressions are not straightforward, are greatly useful in interacting many-body systems such as quantum spin chains. We illustrate the use of this concept in quantum cloning and quantum state transfer and we also sketch its extension to nonunitary dynamics

Measurement of np elastic scattering spin-spin correlation parameters at 484, 634, and 788 MeV

International Nuclear Information System (INIS)

Garnett, R.W.

1989-03-01

The spin-spin correlation parameters C/sub LL/ and C/sub SL/ were measured for np elastic scattering at the incident neutron kinetic energy of 634 MeV. Good agreement was obtained with previously measured data. Additionally, the first measurement of the correlation parameter C/sub SS/ was made at the three energies, 484, 634, and 788 MeV. It was found that the new values, in general, do not agree well with phase shift predictions. A study was carried out to determine which of the isospin-0 partial waves will be affected by this new data. It was found that the 1 P 1 partial wave will be affected significantly at all three measurement energies. At 634 and 788 MeV, the 3 S 1 phase shifts will also change. 29 refs., 21 figs., 16 tabs

Inhomogeneous nuclear spin polarization induced by helicity-modulated optical excitation of fluorine-bound electron spins in ZnSe

Science.gov (United States)

Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.

2015-12-01

Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.

RHIC spin flipper AC dipole controller

Energy Technology Data Exchange (ETDEWEB)

Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.

2011-03-28

The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.

Relativistic spin-orbit interactions of photons and electrons

Science.gov (United States)

Smirnova, D. A.; Travin, V. M.; Bliokh, K. Y.; Nori, F.

2018-04-01

Laboratory optics, typically dealing with monochromatic light beams in a single reference frame, exhibits numerous spin-orbit interaction phenomena due to the coupling between the spin and orbital degrees of freedom of light. Similar phenomena appear for electrons and other spinning particles. Here we examine transformations of paraxial photon and relativistic-electron states carrying the spin and orbital angular momenta (AM) under the Lorentz boosts between different reference frames. We show that transverse boosts inevitably produce a rather nontrivial conversion from spin to orbital AM. The converted part is then separated between the intrinsic (vortex) and extrinsic (transverse shift or Hall effect) contributions. Although the spin, intrinsic-orbital, and extrinsic-orbital parts all point in different directions, such complex behavior is necessary for the proper Lorentz transformation of the total AM of the particle. Relativistic spin-orbit interactions can be important in scattering processes involving photons, electrons, and other relativistic spinning particles, as well as when studying light emitted by fast-moving bodies.

Nonlinear spin wave coupling in adjacent magnonic crystals

Energy Technology Data Exchange (ETDEWEB)

Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

2016-07-25

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

Nonlinear spin wave coupling in adjacent magnonic crystals

International Nuclear Information System (INIS)

Sadovnikov, A. V.; Nikitov, S. A.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E.

2016-01-01

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

Spin-orbit qubit in a semiconductor nanowire.

Science.gov (United States)

Nadj-Perge, S; Frolov, S M; Bakkers, E P A M; Kouwenhoven, L P

2010-12-23

Motion of electrons can influence their spins through a fundamental effect called spin-orbit interaction. This interaction provides a way to control spins electrically and thus lies at the foundation of spintronics. Even at the level of single electrons, the spin-orbit interaction has proven promising for coherent spin rotations. Here we implement a spin-orbit quantum bit (qubit) in an indium arsenide nanowire, where the spin-orbit interaction is so strong that spin and motion can no longer be separated. In this regime, we realize fast qubit rotations and universal single-qubit control using only electric fields; the qubits are hosted in single-electron quantum dots that are individually addressable. We enhance coherence by dynamically decoupling the qubits from the environment. Nanowires offer various advantages for quantum computing: they can serve as one-dimensional templates for scalable qubit registers, and it is possible to vary the material even during wire growth. Such flexibility can be used to design wires with suppressed decoherence and to push semiconductor qubit fidelities towards error correction levels. Furthermore, electrical dots can be integrated with optical dots in p-n junction nanowires. The coherence times achieved here are sufficient for the conversion of an electronic qubit into a photon, which can serve as a flying qubit for long-distance quantum communication.

Ultracoherent operation of spin qubits with superexchange coupling

Science.gov (United States)

Rančić, Marko J.; Burkard, Guido

2017-11-01

With the use of nuclear-spin-free materials such as silicon and germanium, spin-based quantum bits (qubits) have evolved to become among the most coherent systems for quantum information processing. The new frontier for spin qubits has therefore shifted to the ubiquitous charge noise and spin-orbit interaction, which are limiting the coherence times and gate fidelities of solid-state qubits. In this paper we investigate superexchange, as a means of indirect exchange interaction between two single electron spin qubits, each embedded in a single semiconductor quantum dot (QD), mediated by an intermediate, empty QD. Our results suggest the existence of "supersweet spots", in which the qubit operations implemented by superexchange interaction are simultaneously first-order-insensitive to charge noise and to errors due to spin-orbit interaction. The proposed spin-qubit architecture is scalable and within the manufacturing capabilities of semiconductor industry.

Nuclear Spin Nanomagnet in an Optically Excited Quantum Dot

Science.gov (United States)

Korenev, V. L.

2007-12-01

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins—the nuclear spin nanomagnet.

Proton chemical shift tensors determined by 3D ultrafast MAS double-quantum NMR spectroscopy

International Nuclear Information System (INIS)

Zhang, Rongchun; Mroue, Kamal H.; Ramamoorthy, Ayyalusamy

2015-01-01

Proton NMR spectroscopy in the solid state has recently attracted much attention owing to the significant enhancement in spectral resolution afforded by the remarkable advances in ultrafast magic angle spinning (MAS) capabilities. In particular, proton chemical shift anisotropy (CSA) has become an important tool for obtaining specific insights into inter/intra-molecular hydrogen bonding. However, even at the highest currently feasible spinning frequencies (110–120 kHz), 1 H MAS NMR spectra of rigid solids still suffer from poor resolution and severe peak overlap caused by the strong 1 H– 1 H homonuclear dipolar couplings and narrow 1 H chemical shift (CS) ranges, which render it difficult to determine the CSA of specific proton sites in the standard CSA/single-quantum (SQ) chemical shift correlation experiment. Herein, we propose a three-dimensional (3D) 1 H double-quantum (DQ) chemical shift/CSA/SQ chemical shift correlation experiment to extract the CS tensors of proton sites whose signals are not well resolved along the single-quantum chemical shift dimension. As extracted from the 3D spectrum, the F1/F3 (DQ/SQ) projection provides valuable information about 1 H– 1 H proximities, which might also reveal the hydrogen-bonding connectivities. In addition, the F2/F3 (CSA/SQ) correlation spectrum, which is similar to the regular 2D CSA/SQ correlation experiment, yields chemical shift anisotropic line shapes at different isotropic chemical shifts. More importantly, since the F2/F1 (CSA/DQ) spectrum correlates the CSA with the DQ signal induced by two neighboring proton sites, the CSA spectrum sliced at a specific DQ chemical shift position contains the CSA information of two neighboring spins indicated by the DQ chemical shift. If these two spins have different CS tensors, both tensors can be extracted by numerical fitting. We believe that this robust and elegant single-channel proton-based 3D experiment provides useful atomistic-level structural and dynamical

/sup 1/H-NMR chemical shift imaging suitable for low field systems

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Etsuji; Onodera, Takashi; Shiono, Hidemi; Kohno, Hideki

1986-12-01

An echo-time encoding proton NMR chemical shift imaging proposed by Dixon is extended to be applicable to low filed systems. The method utilizes the small phase angle between magnetic vectors of water and lipid protons to decrease the signal decays with spin-spin relaxation. The inevitable phase error caused by the static field inhomogeneity is corrected by using phase images of phantom measured under the same conditions as the actual measurements. The experiments were carried out using CuSO/sub 4/ doped water and vegetable oil at 0.5 T. Two chemical shift images could be clearly resolved with only one scan when the field inhomogeneity was larger than the chemical shift difference.

Note on sideband intensities in one-dimensional magic angle spinning nuclear magnetic resonance

NARCIS (Netherlands)

Well, van H.F.J.M.; Vankan, J.M.J.; Janssen, A.J.E.M.

1991-01-01

It is well known that in the NMR spectra of solid samples spinning at the magic angle centrebands and sidebands occur. The centrebands are found at the isotropic value of the chemical shift and the sidebands are found at integral multiples of the spinning frequency as long as the spinning frequency

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.

MR chemical shift imaging of human atheroma

International Nuclear Information System (INIS)

Mohiaddin, R.H.; Underwood, R.; Firmin, D.; Abdulla, A.K.; Rees, S.; Longmore, D.

1988-01-01

The lipid content of atheromatous plaques has been measured with chemical shift MR imaging by taking advantage of the different resonance frequencies of protons in lipid and water. Fifteen postmortem aortic specimens of the human descending aorta and the aortae of seven patients with documented peripheral vascular disease were studied at 0.5 T. Spin-echo images were used to localize the lesions before acquisition of the chemical shift images. The specimens were examined histologically, and the lipid distribution in the plaque showed good correlation with the chemical shift data. Validation in vivo and clinical applications remain to be established

Spin-valley splitting of electron beam in graphene

Directory of Open Access Journals (Sweden)

Yu Song

2016-11-01

Full Text Available We study spatial separation of the four degenerate spin-valley components of an electron beam in a EuO-induced and top-gated ferromagnetic/pristine/strained graphene structure. We show that, in a full resonant tunneling regime for all beam components, the formation of standing waves can lead sudden phase jumps ∼−π and giant lateral Goos-Hänchen shifts as large as the transverse beam width, while the interplay of the spin and valley imaginary wave vectors in the modulated regions can lead differences of resonant angles for the four spin-valley flavors, manifesting a spin-valley beam splitting effect. The splitting effect is found to be controllable by the gating and strain.

Tuning spin-polarized transport in organic semiconductors

Science.gov (United States)

Mattana, Richard; Galbiati, Marta; Delprat, Sophie; Tatay, Sergio; Deranlot, Cyrile; Seneor, Pierre; Petroff, Frederic

Molecular spintronics is an emerging research field at the frontier between organic chemistry and the spintronics. Compared to traditional inorganic materials molecules are flexible and can be easily tailored by chemical synthesis. Due to their theoretically expected very long spin lifetime, they were first only seen as the ultimate media for spintronics devices. It was recently that new spintronics tailoring could arise from the chemical versatility brought by molecules. The hybridization between a ferromagnet and molecules induces a spin dependent broadening and energy shifting of the molecular orbitals leading to an induced spin polarization on the first molecular layer. This spin dependent hybridization can be used to tailor the spin dependent transport in organic spintronics devices. We have studied vertical Co/Alq3/Co organic spin valves. The negative magnetoresistance observed is the signature of different coupling strengths at the top and bottom interfaces. We have then inserted an inorganic tunnel barrier at the bottom interface in order to suppress the spin-dependent hybridization. In this case we restore a positive magnetoresistance. This demonstrates that at the bottom Co/Alq3 interface a stronger coupling occurs which induces an inversion of the spin polarization.

Application of MSS-neutron spin echo spectrometer to pulsed neutron sources

International Nuclear Information System (INIS)

Tasaki, S.; Ebisawa, T.; Hino, M.; Kawai, T.

2001-01-01

A multilayer spin splitter (MSS) is a neutron device that gives phase difference between field-parallel and -antiparallel spin component of a superposing state. Since the phase difference is equivalent to the Larmor precession angle, MSS enables us to construct a new type of neutron spin echo (NSE) spectrometer. The new NSE spectrometer has its properties that 1. since the phase shift is neutron flight path length, the spectrometer can be drastically small, 2. the neutron spin echo time is proportional to the neutron wavelength. (author)

Measurement of atomic-hydrogen spin-exchange parameters at 0.5 K using a cryogenic hydrogen maser

International Nuclear Information System (INIS)

Hayden, M.E.; Huerlimann, M.D.; Hardy, W.N.

1996-01-01

Using a cryogenic hydrogen maser, suitably modified to have electronic control of both the resonance frequency and the quality factor of the external cavity, we have measured a number of spin-exchange parameters for an atomic-hydrogen (H) gas at a temperature of 0.5 K. These results are relevant to the ultimate achievable frequency stability for cryogenic H masers and, when coupled with accurate calculations of the spin-exchange parameters, serve as a sensitive test of the H-H interatomic potentials. We find evidence for a frequency shift not predicted by semiclassical theories of spin exchange. In the context of a fully quantum mechanical hydrogen-atom spin-exchange theory [B. J. Verhaar et al., Phys. Rev. A 35, 3825 (1987) and J. M. V. A. Koelman et al., Phys. Rev. A 38, 3535 (1988)], this frequency shift is attributed to the influence of hyperfine interactions during spin-exchange collisions. Our findings are generally in agreement with these predictions; however, the sign of the hyperfine-induced frequency shift appears to differ from theory. copyright 1996 The American Physical Society

Effect of Phase Shift in Dual-Rail Perfect State Transfer

International Nuclear Information System (INIS)

Wang Zhao-Ming; Zhang Zhong-Jun; Gu Yong-Jian

2014-01-01

We investigate the effect of phase shift on the perfect state transfer through two parallel one-dimensional ring-shaped spin chains. We find that the total success probability can be significantly enhanced by phase shift control when the communication channel consists of two odd chains. The average time to gain unit success probability is discussed, showing that a proper phase shift can be used to enhance the efficiency of state transmission. (general)

Effect of spin-orbit coupling on the wave vector and spin dependent transmission probability for the GaN/AlGaN/GaN heterostructure

International Nuclear Information System (INIS)

Li, M; Zhao, Z B; Fan, L B

2015-01-01

The effect of the Rashba and Dresselhaus spin–orbit coupling (SOC) on the transmission of electrons through the GaN/AlGaN/GaN heterostructure is studied. It is found that the Dresselhaus SOC causes the evident dependence of the transmission probability on the spin polarization and the in-plane wave vector of electrons, and also induces evident spin splitting of the resonant peaks in the (E z -k) plane. Because the magnitude of the Rashba SOC is relatively small, its effect on the transmission of electrons is much less. As k increases, the peaks of transmission probability for spin-up electrons (T + ) shift to a higher energy region and increase in magnitude, while the peaks of transmission probability for spin-down electrons (T − ) shift to a lower energy region and decrease in magnitude. The polarization efficiency (P) is found to peak at the resonant energies and increases with the in-plane wave vector. Moreover, the built-in electric field caused by the spontaneous and piezoelectric polarization can increase the amplitude of P. Results obtained here are helpful for the efficient spin injection into the III-nitride heterostructures by nonmagnetic means from the device point of view. (paper)

Noise-Resilient Quantum Computing with a Nitrogen-Vacancy Center and Nuclear Spins.

Science.gov (United States)

Casanova, J; Wang, Z-Y; Plenio, M B

2016-09-23

Selective control of qubits in a quantum register for the purposes of quantum information processing represents a critical challenge for dense spin ensembles in solid-state systems. Here we present a protocol that achieves a complete set of selective electron-nuclear gates and single nuclear rotations in such an ensemble in diamond facilitated by a nearby nitrogen-vacancy (NV) center. The protocol suppresses internuclear interactions as well as unwanted coupling between the NV center and other spins of the ensemble to achieve quantum gate fidelities well exceeding 99%. Notably, our method can be applied to weakly coupled, distant spins representing a scalable procedure that exploits the exceptional properties of nuclear spins in diamond as robust quantum memories.

Probing Spin Crossover in a Solution by Paramagnetic NMR Spectroscopy.

Science.gov (United States)

Pavlov, Alexander A; Denisov, Gleb L; Kiskin, Mikhail A; Nelyubina, Yulia V; Novikov, Valentin V

2017-12-18

Spin transitions in spin-crossover compounds are now routinely studied in the solid state by magnetometry; however, only a few methods exist for studies in solution. The currently used Evans method, which relies on NMR spectroscopy to measure the magnetic susceptibility, requires the availability of a very pure sample of the paramagnetic compound and its exact concentration. To overcome these limitations, we propose an alternative NMR-based technique for evaluating spin-state populations by only using the chemical shifts of a spin-crossover compound; those can be routinely obtained for a solution that contains unknown impurities and paramagnetic admixtures or is contaminated otherwise.

Observation of spin Hall effect in photon tunneling via weak measurements.

Science.gov (United States)

Zhou, Xinxing; Ling, Xiaohui; Zhang, Zhiyou; Luo, Hailu; Wen, Shuangchun

2014-12-09

Photonic spin Hall effect (SHE) manifesting itself as spin-dependent splitting escapes detection in previous photon tunneling experiments due to the fact that the induced beam centroid shift is restricted to a fraction of wavelength. In this work, we report on the first observation of this tiny effect in photon tunneling via weak measurements based on preselection and postselection technique on the spin states. We find that the spin-dependent splitting is even larger than the potential barrier thickness when spin-polarized photons tunneling through a potential barrier. This photonic SHE is attributed to spin-redirection Berry phase which can be described as a consequence of the spin-orbit coupling. These findings provide new insight into photon tunneling effect and thereby offer the possibility of developing spin-based nanophotonic applications.

Observation of Spin Hall Effect in Photon Tunneling via Weak Measurements

Science.gov (United States)

Zhou, Xinxing; Ling, Xiaohui; Zhang, Zhiyou; Luo, Hailu; Wen, Shuangchun

2014-01-01

Photonic spin Hall effect (SHE) manifesting itself as spin-dependent splitting escapes detection in previous photon tunneling experiments due to the fact that the induced beam centroid shift is restricted to a fraction of wavelength. In this work, we report on the first observation of this tiny effect in photon tunneling via weak measurements based on preselection and postselection technique on the spin states. We find that the spin-dependent splitting is even larger than the potential barrier thickness when spin-polarized photons tunneling through a potential barrier. This photonic SHE is attributed to spin-redirection Berry phase which can be described as a consequence of the spin-orbit coupling. These findings provide new insight into photon tunneling effect and thereby offer the possibility of developing spin-based nanophotonic applications. PMID:25487043

Spin excitations in the quasi-two-dimensional charge-ordered insulator α -(BEDT-TTF ) 2I3 probed via 13C NMR

Science.gov (United States)

Ishikawa, Kyohei; Hirata, Michihiro; Liu, Dong; Miyagawa, Kazuya; Tamura, Masafumi; Kanoda, Kazushi

2016-08-01

The spin excitations from the nonmagnetic charge-ordered insulating state of α -(BEDT-TTF ) 2I3 at ambient pressure have been investigated by probing the static and low-frequency dynamic spin susceptibilities via site-selective nuclear magnetic resonance at 13C sites. The site-dependent values of the shift and the spin-lattice relaxation rate 1 /T1 below the charge-ordering transition temperature (TCO≈135 K ) demonstrate a spin density imbalance in the unit cell, in accord with the charge-density ratio reported earlier. The shift and 1 /T1 show activated temperature dependence with a static (shift) gap ΔS≈47 -52 meV and a dynamic (1 /T1 ) gap ΔR≈40 meV . The sizes of the gaps are well described in terms of a localized spin model, where spin-1/2 antiferromagnetic dimer chains are weakly coupled with each other.

Identical and shifted identical bands

International Nuclear Information System (INIS)

Dodder, R.S; Jones, E.F.; Hamilton, J.H.

1997-01-01

Spontaneous fission of 252 Cm was studied with 72 large Compton suppressed Ge detectors in Gamma sphere. New isotopes 160 Sm and 162 Gd were identified. Through X-ray-γ and γ-γ-γ) coincidence measurements, level energies were established to spins 14 + to 20 + in 152 , 154 156 60 Nd 92 94 96 , 156 , 158 , 160 62 Sm 94 , 96 , 98 , and 160 , 162 64 Gd 96 , 98 . These nuclei exhibit a remarkable variety of identical bands and bands where the energies and moments of inertia are shifted by the same constant amount for every spin state from 2 + to 12 + for various combinations of nuclei differing by 2n, 4n, 2p, 4p, and α

Sine-squared shifted pulses for recoupling interactions in solid-state NMR

Science.gov (United States)

Jain, Mukul G.; Rajalakshmi, G.; Equbal, Asif; Mote, Kaustubh R.; Agarwal, Vipin; Madhu, P. K.

2017-06-01

Rotational-Echo DOuble-Resonance (REDOR) is a versatile experiment for measuring internuclear distance between two heteronuclear spins in solid-state NMR. At slow to intermediate magic-angle spinning (MAS) frequencies, the measurement of distances between strongly coupled spins is challenging due to rapid dephasing of magnetisation. This problem can be remedied by employing the pulse-shifted version of REDOR known as Shifted-REDOR (S-REDOR) that scales down the recoupled dipolar coupling. In this study, we propose a new variant of the REDOR sequence where the positions of the π pulses are determined by a sine-squared function. This new variant has scaling properties similar to S-REDOR. We use theory, numerical simulations, and experiments to compare the dipolar recoupling efficiencies and the experimental robustness of the three REDOR schemes. The proposed variant has advantages in terms of radiofrequency field requirements at fast MAS frequencies.

Investigations on resolution enhancement in EPR by means of electron spin echoes

International Nuclear Information System (INIS)

Merks, R.P.J.

1979-01-01

The electron spin echo technique has been applied in four types of experiments: the measurement of electric field induced shifts of the EPR line; the detection of electron spin echo ENDOR; a relaxation measurement and the measurement of hyperfine interactions via the nuclear modulation effect. (Auth.)

RECOILING SUPERMASSIVE BLACK HOLES IN SPIN-FLIP RADIO GALAXIES

International Nuclear Information System (INIS)

Liu, F. K.; Wang Dong; Chen Xian

2012-01-01

Numerical relativity simulations predict that coalescence of supermassive black hole (SMBH) binaries leads not only to a spin flip but also to a recoiling of the merger remnant SMBHs. In the literature, X-shaped radio sources are popularly suggested to be candidates for SMBH mergers with spin flip of jet-ejecting SMBHs. Here we investigate the spectral and spatial observational signatures of the recoiling SMBHs in radio sources undergoing black hole spin flip. Our results show that SMBHs in most spin-flip radio sources have mass ratio q ∼> 0.3 with a minimum possible value q min ≅ 0.05. For major mergers, the remnant SMBHs can get a kick velocity as high as 2100 km s –1 in the direction within an angle ∼< 40° relative to the spin axes of remnant SMBHs, implying that recoiling quasars are biased to be with high Doppler-shifted broad emission lines while recoiling radio galaxies are biased to large apparent spatial off-center displacements. We also calculate the distribution functions of line-of-sight velocity and apparent spatial off-center displacements for spin-flip radio sources with different apparent jet reorientation angles. Our results show that the larger the apparent jet reorientation angle is, the larger the Doppler-shifting recoiling velocity and apparent spatial off-center displacement will be. We investigate the effects of recoiling velocity on the dust torus in spin-flip radio sources and suggest that recoiling of SMBHs would lead to 'dust-poor' active galactic nuclei. Finally, we collect a sample of 19 X-shaped radio objects and for each object give the probability of detecting the predicted signatures of recoiling SMBH.

Electron spin resonance in YbRh2Si2: local-moment, unlike-spin and quasiparticle descriptions.

Science.gov (United States)

Huber, D L

2012-06-06

Electron spin resonance (ESR) in the Kondo lattice compound YbRh(2)Si(2) has stimulated discussion as to whether the low-field resonance outside the Fermi liquid regime in this material is more appropriately characterized as a local-moment phenomenon or one that requires a Landau quasiparticle interpretation. In earlier work, we outlined a collective mode approach to the ESR that involves only the local 4f moments. In this paper, we extend the collective mode approach to a situation where there are two subsystems of unlike spins: the pseudospins of the ground multiplet of the Yb ions and the spins of the itinerant conduction electrons. We assume a weakly anisotropic exchange interaction between the two subsystems. With suitable approximations our expression for the g-factor also reproduces that found in recent unlike-spin quasiparticle calculations. It is pointed out that the success of the local-moment approach in describing the resonance is due to the fact that the susceptibility of the Yb subsystem dominates that of the conduction electrons with the consequence that the relative shift in the resonance frequency predicted by the unlike-spin models (and absent in the local-moment models) is ≪ 1. The connection with theoretical studies of a two-component model with like spins is also discussed.

Polarization of nuclear spins by a cold nanoscale resonator

International Nuclear Information System (INIS)

Butler, Mark C.; Weitekamp, Daniel P.

2011-01-01

A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are ''frozen out,'' spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes ''trapped'' away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy

Spin-orbit ZORA and four-component Dirac-Coulomb estimation of relativistic corrections to isotropic nuclear shieldings and chemical shifts of noble gas dimers.

Science.gov (United States)

Jankowska, Marzena; Kupka, Teobald; Stobiński, Leszek; Faber, Rasmus; Lacerda, Evanildo G; Sauer, Stephan P A

2016-02-05

Hartree-Fock and density functional theory with the hybrid B3LYP and general gradient KT2 exchange-correlation functionals were used for nonrelativistic and relativistic nuclear magnetic shielding calculations of helium, neon, argon, krypton, and xenon dimers and free atoms. Relativistic corrections were calculated with the scalar and spin-orbit zeroth-order regular approximation Hamiltonian in combination with the large Slater-type basis set QZ4P as well as with the four-component Dirac-Coulomb Hamiltonian using Dyall's acv4z basis sets. The relativistic corrections to the nuclear magnetic shieldings and chemical shifts are combined with nonrelativistic coupled cluster singles and doubles with noniterative triple excitations [CCSD(T)] calculations using the very large polarization-consistent basis sets aug-pcSseg-4 for He, Ne and Ar, aug-pcSseg-3 for Kr, and the AQZP basis set for Xe. For the dimers also, zero-point vibrational (ZPV) corrections are obtained at the CCSD(T) level with the same basis sets were added. Best estimates of the dimer chemical shifts are generated from these nuclear magnetic shieldings and the relative importance of electron correlation, ZPV, and relativistic corrections for the shieldings and chemical shifts is analyzed. © 2015 Wiley Periodicals, Inc.

State-Transition-Aware Spilling Heuristic for MLC STT-RAM-Based Registers

Directory of Open Access Journals (Sweden)

Yuanhui Ni

2017-01-01

Full Text Available Multilevel Cell Spin-Transfer Torque Random Access Memory (MLC STT-RAM is a promising nonvolatile memory technology to build registers for its natural immunity to electromagnetic radiation in rad-hard space environment. Unlike traditional SRAM-based registers, MLC STT-RAM exhibits unbalanced write state transitions due to the fact that the magnetization directions of hard and soft domains cannot be flipped independently. This feature leads to nonuniform costs of write states in terms of latency and energy. However, current SRAM-targeting register allocations do not have a clear understanding of the impact of the different write state-transition costs. As a result, those approaches heuristically select variables to be spilled without considering the spilling priority imposed by MLC STT-RAM. Aiming to address this limitation, this paper proposes a state-transition-aware spilling cost minimization (SSCM policy, to save power when MLC STT-RAM is employed in register design. Specifically, the spilling cost model is first constructed according to the linear combination of different state-transition frequencies. Directed by the proposed cost model, the compiler picks up spilling candidates to achieve lower power and higher performance. Experimental results show that the proposed SSCM technique can save energy by 19.4% and improve the lifetime by 23.2% of MLC STT-RAM-based register design.

Spin coherence transfer in chemical transformations monitoredNMR

Energy Technology Data Exchange (ETDEWEB)

Anwar, Sabieh M.; Hilty, Christian; Chu, Chester; Bouchard,Louis-S.; Pierce, Kimberly L.; Pines, Alexander

2006-07-31

We demonstrate the use of micro-scale nuclear magneticresonance (NMR) for studying the transfer of spin coherence innon-equilibrium chemical processes, using spatially separated NMRencoding and detection coils. As an example, we provide the map ofchemical shift correlations for the amino acid alanine as it transitionsfrom the zwitterionic to the anionic form. Our method is unique in thesense that it allows us to track the chemical migration of encodednuclear spins during the course of chemical transformations.

Coherent Rabi Dynamics of a Superradiant Spin Ensemble in a Microwave Cavity

Science.gov (United States)

Rose, B. C.; Tyryshkin, A. M.; Riemann, H.; Abrosimov, N. V.; Becker, P.; Pohl, H.-J.; Thewalt, M. L. W.; Itoh, K. M.; Lyon, S. A.

2017-07-01

We achieve the strong-coupling regime between an ensemble of phosphorus donor spins in a highly enriched 28Si crystal and a 3D dielectric resonator. Spins are polarized beyond Boltzmann equilibrium using spin-selective optical excitation of the no-phonon bound exciton transition resulting in N =3.6 ×1 013 unpaired spins in the ensemble. We observe a normal mode splitting of the spin-ensemble-cavity polariton resonances of 2 g √{N }=580 kHz (where each spin is coupled with strength g ) in a cavity with a quality factor of 75 000 (γ ≪κ ≈60 kHz , where γ and κ are the spin dephasing and cavity loss rates, respectively). The spin ensemble has a long dephasing time (T2*=9 μ s ) providing a wide window for viewing the dynamics of the coupled spin-ensemble-cavity system. The free-induction decay shows up to a dozen collapses and revivals revealing a coherent exchange of excitations between the superradiant state of the spin ensemble and the cavity at the rate g √{N }. The ensemble is found to evolve as a single large pseudospin according to the Tavis-Cummings model due to minimal inhomogeneous broadening and uniform spin-cavity coupling. We demonstrate independent control of the total spin and the initial Z projection of the psuedospin using optical excitation and microwave manipulation, respectively. We vary the microwave excitation power to rotate the pseudospin on the Bloch sphere and observe a long delay in the onset of the superradiant emission as the pseudospin approaches full inversion. This delay is accompanied by an abrupt π -phase shift in the peusdospin microwave emission. The scaling of this delay with the initial angle and the sudden phase shift are explained by the Tavis-Cummings model.

Counter-rotating standing spin waves: A magneto-optical illusion

Science.gov (United States)

Shihab, S.; Thevenard, L.; Lemaître, A.; Gourdon, C.

2017-04-01

We excite perpendicular standing spin waves by a laser pulse in a GaMnAsP ferromagnetic layer and detect them using time-resolved magneto-optical effects. Quite counterintuitively, we find the first two excited modes to be of opposite chirality. We show that this can only be explained by taking into account absorption and optical phase shift inside the layer. This optical illusion is particularly strong in weakly absorbing layers. These results provide a correct identification of spin waves modes, enabling a trustworthy estimation of their respective weight as well as an unambiguous determination of the spin stiffness parameter.

Current-induced spin transfer torque in ferromagnet-marginal Fermi liquid double tunnel junctions

International Nuclear Information System (INIS)

Mu Haifeng; Zheng Qingrong; Jin Biao; Su Gang

2005-01-01

Current-induced spin transfer torque through a marginal Fermi liquid (MFL) which is connected to two noncollinearly aligned ferromagnets via tunnel junctions is discussed in terms of the nonequilibrium Green function method. It is found that in the absence of the spin-flip scattering, the magnitude of the torque increases with the polarization and the coupling constant λ of the MFL, whose maximum increases with λ linearly, showing that the interactions between electrons tend to enhance the spin torque. When the spin-flip scattering is included, an additional spin torque is induced. It is found that the spin-flip scattering enhances the spin torque and gives rise to a nonlinear angular shift

Spin orientation in solid solution hematite-ilmenite

DEFF Research Database (Denmark)

Brok, Erik; Frandsen, Cathrine; Lefmann, Kim

2017-01-01

temperature range below the Néel temperature and does not depend systematically on Ti-content. The results indicate that the out-of-plane spin component is an intrinsic feature of hematite itself, with an origin not yet fully understood, but consistent with group theory. This represents a major shift...... spectroscopy. The usually assumed magnetic structure of hematite within this temperature range is antiferromagnetic with the spins confined to the basal plane of the hexagonal structure; however, an out-of-plane spin component is allowed by the symmetry of the system and has been observed in recent studies......The spin orientation in synthetic hematite-ilmenite samples and in a sample of natural hematite was studied from room temperature to above the antiferromagnetic-paramagnetic phase transition (the Néel temperature; TN ≈ 600–950 K) by neutron powder diffraction and at room temperature by Mössbauer...

Changes in nurses' decision making during a 12-h day shift.

Science.gov (United States)

McClelland, L E; Switzer, F S; Pilcher, J J

2013-01-01

Although shift work is necessary in many health-care settings, research suggests that it can have detrimental effects on performance in health-care providers. To determine if a change in decision-making occurred across a 12-h day shift in a sample of registered nurses. The participants were nurses working a 12-h day shift (7 a.m.-7 p.m.) at a large hospital in the south-eastern USA. Participants completed a policy-capturing questionnaire, examining their likelihood of calling a physician in response to specific patient symptoms, at the beginning and end of the shift. They also completed self-report surveys on alertness, stress and sleepiness. Sixty-five nurses completed the study, an overall response rate of 41%. Participants significantly changed their decision-making policies from the beginning to the end of the work shift and also became significantly less alert and more stressed. However, there was no correlation between decision-making and reported alertness and stress. These results suggest that medical judgment in registered nurses changed from the beginning to the end of a 12-h day shift. One possible underlying mechanism responsible for the changes seen across the shift could be the ability to maintain attention, as suggested by the Controlled Attention Model. The current results expand upon previous research, indicating there are a variety of negative outcomes associated with shift work.

Rotary spin echoes

Energy Technology Data Exchange (ETDEWEB)

Solomon, I. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes Nucleaires de Saclay, BP2, Gif-sur-Yvette (France)

1959-07-01

Torrey has observed the free precession of nuclear spins around an r-f field H{sub 1}, fixed in a frame rotating at the Larmor frequency ω{sub 0} = γH{sub 0} around a large d-c magnetic field H{sub 0}. He showed that for an H{sub 1}, much larger than inhomogeneity of H{sub 0}, the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H{sub 1}. We report here on a method of overcoming the inhomogeneity of H{sub 1}, by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H{sub 1}, is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302.

Rotary spin echoes

International Nuclear Information System (INIS)

Solomon, I.

1959-01-01

Torrey has observed the free precession of nuclear spins around an r-f field H 1 , fixed in a frame rotating at the Larmor frequency ω 0 = γH 0 around a large d-c magnetic field H 0 . He showed that for an H 1 , much larger than inhomogeneity of H 0 , the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H 1 . We report here on a method of overcoming the inhomogeneity of H 1 , by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H 1 , is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302

Microelectromechanical systems integrating molecular spin crossover actuators

Energy Technology Data Exchange (ETDEWEB)

Manrique-Juarez, Maria D. [LCC, CNRS and Université de Toulouse, UPS, INP, F-31077 Toulouse (France); LAAS, CNRS and Université de Toulouse, INSA, UPS, F-31077 Toulouse (France); Rat, Sylvain; Salmon, Lionel; Molnár, Gábor; Bousseksou, Azzedine, E-mail: liviu.nicu@laas.fr, E-mail: azzedine.bousseksou@lcc-toulouse.fr [LCC, CNRS and Université de Toulouse, UPS, INP, F-31077 Toulouse (France); Mathieu, Fabrice; Saya, Daisuke; Séguy, Isabelle; Leïchlé, Thierry; Nicu, Liviu, E-mail: liviu.nicu@laas.fr, E-mail: azzedine.bousseksou@lcc-toulouse.fr [LAAS, CNRS and Université de Toulouse, INSA, UPS, F-31077 Toulouse (France)

2016-08-08

Silicon MEMS cantilevers coated with a 200 nm thin layer of the molecular spin crossover complex [Fe(H{sub 2}B(pz){sub 2}){sub 2}(phen)] (H{sub 2}B(pz){sub 2} = dihydrobis(pyrazolyl)borate and phen = 1,10-phenantroline) were actuated using an external magnetic field and their resonance frequency was tracked by means of integrated piezoresistive detection. The light-induced spin-state switching of the molecules from the ground low spin to the metastable high spin state at 10 K led to a well-reproducible shift of the cantilever's resonance frequency (Δf{sub r} = −0.52 Hz). Control experiments at different temperatures using coated as well as uncoated devices along with simple calculations support the assignment of this effect to the spin transition. This latter translates into changes in mechanical behavior of the cantilever due to the strong spin-state/lattice coupling. A guideline for the optimization of device parameters is proposed so as to efficiently harness molecular scale movements for large-scale mechanical work, thus paving the road for nanoelectromechanical systems (NEMS) actuators based on molecular materials.

Spin-filter effect in normal metal/ferromagnetic insulator/normal metal/superconductor structures

International Nuclear Information System (INIS)

Li, Hong; Yang, Wei; Yang, Xinjian; Qin, Minghui; Guo, Jianqin

2007-01-01

Taking into account the thickness of the ferromagnetic insulator, the spin-filter effect in normal metal/ferromagnetic insulator/normal metal/superconductor (NM/FI/NM/SC) junctions is studied based on the Blonder-Tinkham-Klapwijk (BTK) theory. It is shown that a spin-dependent energy shift during the tunneling process induces splitting of the subgap resonance peaks. The spin polarization due to the spin-filter effect of the FI causes an imbalance of the peaks heights and can enhance the Zeeman splitting of the gap peaks caused by an applied magnetic field. The spin-filter effect has no contribution to the proximity-effect-induced superconductivity in NM interlayer

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.

Microwave imaging of spinning object using orbital angular momentum

Science.gov (United States)

Liu, Kang; Li, Xiang; Gao, Yue; Wang, Hongqiang; Cheng, Yongqiang

2017-09-01

The linear Doppler shift used for the detection of a spinning object becomes significantly weakened when the line of sight (LOS) is perpendicular to the object, which will result in the failure of detection. In this paper, a new detection and imaging technique for spinning objects is developed. The rotational Doppler phenomenon is observed by using the microwave carrying orbital angular momentum (OAM). To converge the radiation energy on the area where objects might exist, the generation method of OAM beams is proposed based on the frequency diversity principle, and the imaging model is derived accordingly. The detection method of the rotational Doppler shift and the imaging approach of the azimuthal profiles are proposed, which are verified by proof-of-concept experiments. Simulation and experimental results demonstrate that OAM beams can still be used to obtain the azimuthal profiles of spinning objects even when the LOS is perpendicular to the object. This work remedies the insufficiency in existing microwave sensing technology and offers a new solution to the object identification problem.

Anisotropic magnetic interactions and spin dynamics in the spin-chain compound Cu (py) 2Br2 : An experimental and theoretical study

Science.gov (United States)

Zeisner, J.; Brockmann, M.; Zimmermann, S.; Weiße, A.; Thede, M.; Ressouche, E.; Povarov, K. Yu.; Zheludev, A.; Klümper, A.; Büchner, B.; Kataev, V.; Göhmann, F.

2017-07-01

We compare theoretical results for electron spin resonance (ESR) properties of the Heisenberg-Ising Hamiltonian with ESR experiments on the quasi-one-dimensional magnet Cu (py) 2Br2 (CPB). Our measurements were performed over a wide frequency and temperature range giving insight into the spin dynamics, spin structure, and magnetic anisotropy of this compound. By analyzing the angular dependence of ESR parameters (resonance shift and linewidth) at room temperature, we show that the two weakly coupled inequivalent spin-chain types inside the compound are well described by Heisenberg-Ising chains with their magnetic anisotropy axes perpendicular to the chain direction and almost perpendicular to each other. We further determine the full g tensor from these data. In addition, the angular dependence of the linewidth at high temperatures gives us access to the exponent of the algebraic decay of a dynamical correlation function of the isotropic Heisenberg chain. From the temperature dependence of static susceptibilities, we extract the strength of the exchange coupling (J /kB=52.0 K ) and the anisotropy parameter (δ ≈-0.02 ) of the model Hamiltonian. An independent compatible value of δ is obtained by comparing the exact prediction for the resonance shift at low temperatures with high-frequency ESR data recorded at 4 K . The spin structure in the ordered state implied by the two (almost) perpendicular anisotropy axes is in accordance with the propagation vector determined from neutron scattering experiments. In addition to undoped samples, we study the impact of partial substitution of Br by Cl ions on spin dynamics. From the dependence of the ESR linewidth on the doping level, we infer an effective decoupling of the anisotropic component J δ from the isotropic exchange J in these systems.

Effect of electron-photon interaction on the knight shift

International Nuclear Information System (INIS)

Tripathi, G.S.; Misra, C.M.; Tripathi, P.; Misra, P.K.

1990-01-01

The effect of electron-phonon interaction is considered on the spin (K s ), orbital (K o ) and spin-orbit (K so ) contributions to the Knight shift. In case of K s , it is found that the modifications caused due to the magnetic field dependence of electron self-energy in the presence of electron-phonon interaction is cancelled by the electron-phonon mass enhancement. However, in the presence of both electron-electron and electron-phonon interactions, the exchange enhancement parameter α is modified to α(1+γ) -1 where γ is the electron-phonon mass enhancement parameter. The orbital and spin-orbital contributions are mainly modified through the changes in the one-electron energies and wave functions. (orig.)

Das sprachliche Register (Speech Registers)

Science.gov (United States)

Hess-Luttich, Ernest W. B.

1974-01-01

The linguistic behavior of a given individual varies; he will on different occasions speak (or write) differently according to what may be roughly described as different social situations: he will use a number of different registers. The application of such registers both in the field of text analysis and in the preparation of teaching materials…

Production of a pseudo-random square wave using a shift register with binary feedbacks; Generation d'un creneau pseudo-aleatoire par un registre a decalage a contre-reaction binaire

Energy Technology Data Exchange (ETDEWEB)

Stern, T E; Cazemajou, J; Macherez, B; Valat, J; Vignon, A

1964-07-01

We summarize here the theoretical basis for the production of square wave having the values '1' or '0', the switching times being 'pseudo-random'. More precisely, the square-wave may or may not change value at regular time intervals of length {delta}, with probability approximately. 5 for each alternative. The wave-form is obtained by means of a shift-register having modulo-2 feedback. If the interval {delta} and the feedback connections are well chosen, it is possible to produce a waveform whose autocorrelation function is very close to a Dirac delta function. The square-wave therefore behaves like a quantized white noise, which has very interesting properties in cross-correlation techniques. (authors) [French] On resume ici les bases theoriques permettant d'obtenir un creneau prenant les valeurs '1' ou '0', les instants de commutation etant pseudo-aleatoires. Plus exactement, le creneau a la possibilite de changer (ou de ne pas changer) d'etat a intervalles de temps reguliers, separes par intervalle elementaire {delta}, chacune des deux possibilites possedant une probabilite d'apparition tres voisine de 0,5. Le creneau est obtenu par un registre a decalage (shift register) a contre-reactions logiques modulo-2. Si l'intervalle {delta} et les contre-reactions sont judicieusement choisis, il est possible d'obtenir pour le creneau une fonction d'autocorrelation triangulaire tres voisine d'une impulsion de Dirac. Par suite le creneau se comporte comme un bruit blanc quantifie possedant de tres interessantes proprietes pour les techniques statistiques d'intercorrelation. (auteurs)

The su(2 vertical bar 3) dynamic spin chain

International Nuclear Information System (INIS)

Beisert, Niklas

2004-01-01

The complete one-loop, planar dilatation operator of the N=4 superconformal gauge theory was recently derived and shown to be integrable. Here, we present further compelling evidence for a generalisation of this integrable structure to higher orders of the coupling constant. For that we consider the su(2 vertical bar 3) subsector and investigate the restrictions imposed on the spin chain Hamiltonian by the symmetry algebra. This allows us to uniquely fix the energy shifts up to the three-loop level and thus prove the correctness of a conjecture in hep-th/0303060. A novel aspect of this spin chain model is that the higher-loop Hamiltonian, as for N=4 SYM in general, does not preserve the number of spin sites. Yet this dynamic spin chain appears to be integrable

Spectral fitting for signal assignment and structural analysis of uniformly {sup 13}C-labeled solid proteins by simulated annealing based on chemical shifts and spin dynamics

Energy Technology Data Exchange (ETDEWEB)

Matsuki, Yoh; Akutsu, Hideo; Fujiwara, Toshimichi [Osaka University, Institute for Protein Research (Japan)], E-mail: tfjwr@protein.osaka-u.ac.jp

2007-08-15

We describe an approach for the signal assignment and structural analysis with a suite of two-dimensional {sup 13}C-{sup 13}C magic-angle-spinning solid-state NMR spectra of uniformly {sup 13}C-labeled peptides and proteins. We directly fit the calculated spectra to experimental ones by simulated annealing in restrained molecular dynamics program CNS as a function of atomic coordinates. The spectra are calculated from the conformation dependent chemical shift obtained with SHIFTX and the cross-peak intensities computed for recoupled dipolar interactions. This method was applied to a membrane-bound 14-residue peptide, mastoparan-X. The obtained C', C{sup {alpha}} and C{sup {beta}} chemical shifts agreed with those reported previously at the precisions of 0.2, 0.7 and 0.4 ppm, respectively. This spectral fitting program also provides backbone dihedral angles with a precision of about 50 deg. from the spectra even with resonance overlaps. The restraints on the angles were improved by applying protein database program TALOS to the obtained chemical shifts. The peptide structure provided by these restraints was consistent with the reported structure at the backbone RMSD of about 1 A.

Brillouin-Mandelstam spectroscopy of standing spin waves in a ferrite waveguide

Science.gov (United States)

Balinskiy, Michael; Kargar, Fariborz; Chiang, Howard; Balandin, Alexander A.; Khitun, Alexander G.

2018-05-01

This article reports results of experimental investigation of the spin wave interference over large distances in the Y3Fe2(FeO4)3 waveguide using Brillouin-Mandelstam spectroscopy. Two coherent spin waves are excited by the micro-antennas fabricated at the edges of the waveguide. The amplitudes of the input spin waves are adjusted to provide approximately the same intensity in the central region of the waveguide. The relative phase between the excited spin waves is controlled by the phase shifter. The change of the local intensity distribution in the standing spin wave is monitored using Brillouin-Mandelstam light scattering spectroscopy. Experimental data demonstrate the oscillation of the scattered light intensity depending on the relative phase of the interfering spin waves. The oscillations of the intensity, tunable via the relative phase shift, are observed as far as 7.5 mm away from the spin-wave generating antennas at room temperature. The obtained results are important for developing techniques for remote control of spin currents, with potential applications in spin-based memory and logic devices.

Individual vulnerability to insomnia, excessive sleepiness and shift work disorder amongst healthcare shift workers. A systematic review.

Science.gov (United States)

Booker, Lauren A; Magee, Michelle; Rajaratnam, Shantha M W; Sletten, Tracey L; Howard, Mark E

2018-03-27

Shift workers often experience reduced sleep quality, duration and/or excessive sleepiness due to the imposed conflict between work and their circadian system. About 20-30% of shift workers experience prominent insomnia symptoms and excessive daytime sleepiness consistent with the circadian rhythm sleep disorder known as shift work disorder. Individual factors may influence this vulnerability to shift work disorder or sleep-related impairment associated with shift work. This paper was registered with Prospero and was conducted using recommended standards for systematic reviews and meta-analyses. Published literature that measured sleep-related impairment associated with shift work including reduced sleep quality and duration and increased daytime sleepiness amongst healthcare shift workers and explored characteristics associated with individual variability were reviewed. Fifty-eight studies were included. Older age, morning-type, circadian flexibility, being married or having children, increased caffeine intake, higher scores on neuroticism and lower on hardiness were related to a higher risk of sleep-related impairment in response to shift work, whereas physical activity was a protective factor. The review highlights the diverse range of measurement tools used to evaluate the impact of shift work on sleep. Use of standardised and validated tools would enable cross-study comparisons. Longitudinal studies are required to establish causal relationships between individual factors and the development of shift work disorder. Copyright © 2018 Elsevier Ltd. All rights reserved.

Intrinsic anharmonic effects on the phonon frequencies and effective spin-spin interactions in a quantum simulator made from trapped ions in a linear Paul trap

Science.gov (United States)

McAneny, M.; Freericks, J. K.

2014-11-01

The Coulomb repulsion between ions in a linear Paul trap gives rise to anharmonic terms in the potential energy when expanded about the equilibrium positions. We examine the effect of these anharmonic terms on the accuracy of a quantum simulator made from trapped ions. To be concrete, we consider a linear chain of Yb171+ ions stabilized close to the zigzag transition. We find that for typical experimental temperatures, frequencies change by no more than a factor of 0.01 % due to the anharmonic couplings. Furthermore, shifts in the effective spin-spin interactions (driven by a spin-dependent optical dipole force) are also, in general, less than 0.01 % for detunings to the blue of the transverse center-of-mass frequency. However, detuning the spin interactions near other frequencies can lead to non-negligible anharmonic contributions to the effective spin-spin interactions. We also examine an odd behavior exhibited by the harmonic spin-spin interactions for a range of intermediate detunings, where nearest-neighbor spins with a larger spatial separation on the ion chain interact more strongly than nearest neighbors with a smaller spatial separation.

Nurses’ Shift Length and Overtime Working in 12 European Countries

Science.gov (United States)

Dall’Ora, Chiara; Simon, Michael; Ball, Jane; Lindqvist, Rikard; Rafferty, Anne-Marie; Schoonhoven, Lisette; Tishelman, Carol; Aiken, Linda H.

2014-01-01

Background: Despite concerns as to whether nurses can perform reliably and effectively when working longer shifts, a pattern of two 12- to 13-hour shifts per day is becoming common in many hospitals to reduce shift to shift handovers, staffing overlap, and hence costs. Objectives: To describe shift patterns of European nurses and investigate whether shift length and working beyond contracted hours (overtime) is associated with nurse-reported care quality, safety, and care left undone. Methods: Cross-sectional survey of 31,627 registered nurses in general medical/surgical units within 488 hospitals across 12 European countries. Results: A total of 50% of nurses worked shifts of ≤8 hours, but 15% worked ≥12 hours. Typical shift length varied between countries and within some countries. Nurses working for ≥12 hours were more likely to report poor or failing patient safety [odds ratio (OR)=1.41; 95% confidence interval (CI), 1.13–1.76], poor/fair quality of care (OR=1.30; 95% CI, 1.10–1.53), and more care activities left undone (RR=1.13; 95% CI, 1.09–1.16). Working overtime was also associated with reports of poor or failing patient safety (OR=1.67; 95% CI, 1.51–1.86), poor/fair quality of care (OR=1.32; 95% CI, 1.23–1.42), and more care left undone (RR=1.29; 95% CI, 1.27–1.31). Conclusions: European registered nurses working shifts of ≥12 hours and those working overtime report lower quality and safety and more care left undone. Policies to adopt a 12-hour nursing shift pattern should proceed with caution. Use of overtime working to mitigate staffing shortages or increase flexibility may also incur additional risk to quality. PMID:25226543

$^{11}$B and $^{27}$Al NMR spin-lattice relaxation and Knight shift study of Mg$_{1-x}$Al$_x$B$_2$. Evidence for anisotropic Fermi surface

OpenAIRE

Papavassiliou, G.; Pissas, M.; Karayanni, M.; Fardis, M.; Koutandos, S.; Prassides, K.

2002-01-01

We report a detailed study of $^{11}$B and $^{27}$Al NMR spin-lattice relaxation rates ($1/T_1$), as well as of $^{27}$Al Knight shift (K) of Mg$_{1-x}$Al$_x$B$_2$, $0\\leq x\\leq 1$. The obtained ($1/T_1T$) and K vs. x plots are in excellent agreement with ab initio calculations. This asserts experimentally the prediction that the Fermi surface is highly anisotropic, consisting mainly of hole-type 2-D cylindrical sheets from bonding $2p_{x,y}$ boron orbitals. It is also shown that the density ...

Quasipotential approach to the Coulomb bound state problem for spin-0 and spin-/sup 1///sub 2/ particles

CERN Document Server

Rizov, V A; Todorov, I T

1975-01-01

A recently proposed local quasipotential equation is reviewed and applied to the electromagnetic interaction of a spin-0 and a spin-/sup 1///sub 2/ particle. The Dirac particle is treated in a covariant two- component formalism in the neighbourhood of the mass shell. The fine structure of the bound state energy levels and the main part of the Lamb shift (of order alpha /sup 5/In(1/ alpha ) are evaluated with full account of relativistic recoil effects (without using any inverse mass expansion). Possible relevance of the techniques developed in this paper to fine structure calculations for meso-atomic systems is pointed out. (14 refs).

The spin-orbit interaction in nuclei

International Nuclear Information System (INIS)

Skyrme, T.H.R.

1994-01-01

The analysis previously made of the average nuclear potential has been extended to consideration of the spin-orbit interactions. It has not been possible to find a satisfactory two-body interaction consistent with all the data; that suggested by the phase-shift analysis of nucleon-nucleon scattering is just within the region of possible forms. (author). 13 refs, 1 fig

Mode coupling in spin torque oscillators

International Nuclear Information System (INIS)

Zhang, Steven S.-L.; Zhou, Yan; Li, Dong; Heinonen, Olle

2016-01-01

A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.

Mode coupling in spin torque oscillators

Energy Technology Data Exchange (ETDEWEB)

Zhang, Steven S.-L., E-mail: ZhangShule@missouri.edu [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Zhou, Yan, E-mail: yanzhou@hku.hk [Department of Physics, The University of Hong Kong, Hong Kong (China); Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong (China); Li, Dong, E-mail: geodesic.ld@gmail.com [Department of Physics, Centre for Nonlinear Studies, and Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Heinonen, Olle, E-mail: heinonen@anl.gov [Material Science Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Northwestern-Argonne Institute of Science and Technology, 2145 Sheridan Road, Evanston, IL 60208 (United States); Computation Institute, The Unversity of Chicago, 5735 S Ellis Avenue, Chicago, IL 60637 (United States)

2016-09-15

A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.

Relativistic theory of the Lamb shift based on self energy

International Nuclear Information System (INIS)

Barut, A.O.; Salamin, Y.I.

1987-07-01

A study is made to evaluate the Lamb shift to all orders in (Zα) using relativistic Dirac Coulomb wavefunctions and without resorting to the dipole approximation. Use is made of the angular integrals and spins sums performed elsewhere exactly. A regularization procedure is given that makes the sum over the positive and negative energy states finite. Finally, the energy shift ΔE n LS is given in terms of an integral that may be done numerically. (author). 19 refs

Softness and amplitudes’ positivity for spinning particles

Energy Technology Data Exchange (ETDEWEB)

Bellazzini, Brando [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS,F-91191 Gif-sur-Yvette (France); Dipartimento di Fisica e Astronomia, Università di Padova,Via Marzolo 8, I-35131 Padova (Italy)

2017-02-07

We derive positivity bounds for scattering amplitudes of particles with arbitrary spin using unitarity, analyticity and crossing symmetry. The bounds imply the positivity of certain low-energy coefficients of the effective action that controls the dynamics of the light degrees of freedom. We show that low-energy amplitudes strictly softer than O(p{sup 4}) do not admit unitary ultraviolet completions unless the theory is free. This enforces a bound on the energy growth of scattering amplitudes in the region of validity of the effective theory. We discuss explicit examples including the Goldstino from spontaneous supersymmetry breaking, and the theory of a spin-1/2 fermion with a shift symmetry.

Chip-Scale Combinatorial Atomic Navigator (C-SCAN) Low Drift Nuclear Spin Gyroscope

Science.gov (United States)

2018-01-01

suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704...spin-exchange relaxation in a finite magnetic field. We operated the gyroscope using a Ramsey-type interrogation sequence with nuclear spin precession...shift by a factor of 105. Here we use the approach of a Ramsey clock interrogation scheme, where the optical pumping, free evolution, and measurement

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.

Entangled spins and ghost-spins

Directory of Open Access Journals (Sweden)

Dileep P. Jatkar

2017-09-01

Full Text Available We study patterns of quantum entanglement in systems of spins and ghost-spins regarding them as simple quantum mechanical toy models for theories containing negative norm states. We define a single ghost-spin as in [20] as a 2-state spin variable with an indefinite inner product in the state space. We find that whenever the spin sector is disentangled from the ghost-spin sector (both of which could be entangled within themselves, the reduced density matrix obtained by tracing over all the ghost-spins gives rise to positive entanglement entropy for positive norm states, while negative norm states have an entanglement entropy with a negative real part and a constant imaginary part. However when the spins are entangled with the ghost-spins, there are new entanglement patterns in general. For systems where the number of ghost-spins is even, it is possible to find subsectors of the Hilbert space where positive norm states always lead to positive entanglement entropy after tracing over the ghost-spins. With an odd number of ghost-spins however, we find that there always exist positive norm states with negative real part for entanglement entropy after tracing over the ghost-spins.

Spin Current Noise of the Spin Seebeck Effect and Spin Pumping

Science.gov (United States)

Matsuo, M.; Ohnuma, Y.; Kato, T.; Maekawa, S.

2018-01-01

We theoretically investigate the fluctuation of a pure spin current induced by the spin Seebeck effect and spin pumping in a normal-metal-(NM-)ferromagnet(FM) bilayer system. Starting with a simple ferromagnet-insulator-(FI-)NM interface model with both spin-conserving and non-spin-conserving processes, we derive general expressions of the spin current and the spin-current noise at the interface within second-order perturbation of the FI-NM coupling strength, and estimate them for a yttrium-iron-garnet-platinum interface. We show that the spin-current noise can be used to determine the effective spin carried by a magnon modified by the non-spin-conserving process at the interface. In addition, we show that it provides information on the effective spin of a magnon, heating at the interface under spin pumping, and spin Hall angle of the NM.

STOCHASTIC MODEL OF THE SPIN DISTRIBUTION OF DARK MATTER HALOS

Energy Technology Data Exchange (ETDEWEB)

Kim, Juhan [Center for Advanced Computation, Korea Institute for Advanced Study, Heogiro 85, Seoul 130-722 (Korea, Republic of); Choi, Yun-Young [Department of Astronomy and Space Science, Kyung Hee University, Gyeonggi 446-701 (Korea, Republic of); Kim, Sungsoo S.; Lee, Jeong-Eun [School of Space Research, Kyung Hee University, Gyeonggi 446-701 (Korea, Republic of)

2015-09-15

We employ a stochastic approach to probing the origin of the log-normal distributions of halo spin in N-body simulations. After analyzing spin evolution in halo merging trees, it was found that a spin change can be characterized by a stochastic random walk of angular momentum. Also, spin distributions generated by random walks are fairly consistent with those directly obtained from N-body simulations. We derived a stochastic differential equation from a widely used spin definition and measured the probability distributions of the derived angular momentum change from a massive set of halo merging trees. The roles of major merging and accretion are also statistically analyzed in evolving spin distributions. Several factors (local environment, halo mass, merging mass ratio, and redshift) are found to influence the angular momentum change. The spin distributions generated in the mean-field or void regions tend to shift slightly to a higher spin value compared with simulated spin distributions, which seems to be caused by the correlated random walks. We verified the assumption of randomness in the angular momentum change observed in the N-body simulation and detected several degrees of correlation between walks, which may provide a clue for the discrepancies between the simulated and generated spin distributions in the voids. However, the generated spin distributions in the group and cluster regions successfully match the simulated spin distribution. We also demonstrated that the log-normality of the spin distribution is a natural consequence of the stochastic differential equation of the halo spin, which is well described by the Geometric Brownian Motion model.

Search for electric dipole moment in 129Xe atom using active nuclear spin maser

Directory of Open Access Journals (Sweden)

Ichikawa Y.

2014-03-01

Full Text Available An experimental search for an electric dipole moment in the diamagnetic atom 129Xe is in progress through the precision measurement of spin precession frequency using an active nuclear spin maser. A 3He comagnetometer has been incorporated into the active spin maser system in order to cancel out the long-term drifts in the external magnetic field. Also, a double-cell geometry has been adopted in order to suppress the frequency shifts due to interaction with polarized Rb atoms. The first EDM measurement with the 129Xe active spin maser and the 3He comagnetometer has been conducted.

Measurements of relative chemical shift tensor orientations in solid-state NMR: new slow magic angle spinning dipolar recoupling experiments.

Science.gov (United States)

Jurd, Andrew P S; Titman, Jeremy J

2009-08-28

Solid-state NMR experiments can be used to determine conformational parameters, such as interatomic distances and torsion angles. The latter can be obtained from measurements of the relative orientation of two chemical shift tensors, if the orientation of these with respect to the surrounding bonds is known. In this paper, a new rotor-synchronized magic angle spinning (MAS) dipolar correlation experiment is described which can be used in this way. Because the experiment requires slow MAS rates, a novel recoupling sequence, designed using symmetry principles, is incorporated into the mixing period. This recoupling sequence is based in turn on a new composite cyclic pulse referred to as COAST (for combined offset and anisotropy stabilization). The new COAST-C7(2)(1) sequence is shown to give good theoretical and experimental recoupling efficiency, even when the CSA far exceeds the MAS rate. In this regime, previous recoupling sequences, such as POST-C7(2)(1), exhibit poor recoupling performance. The effectiveness of the new method has been explored by a study of the dipeptide L-phenylalanyl-L-phenylalanine.

Pressure and Temperature Spin Crossover Sensors with Optical Detection

Science.gov (United States)

Linares, Jorge; Codjovi, Epiphane; Garcia, Yann

2012-01-01

Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials. PMID:22666041

Spin-glass polyamorphism induced by a magnetic field in LaMnO3 single crystal

Science.gov (United States)

Eremenko, V. V.; Sirenko, V. A.; Baran, A.; Čižmár, E.; Feher, A.

2018-05-01

We present experimental evidence of field-driven transition in spin-glass state, similar to pressure-induced transition between amorphous phases in structural and metallic glasses, attributed to the polyamorphism phenomena. Cusp in temperature dependences of ac magnetic susceptibility of weakly disordered LaMnO3 single crystal is registered below the temperature of magnetic ordering. Frequency dependence of the cusp temperature proves its spin-glass origin. The transition induced by a magnetic field in spin-glass state, is manifested by peculiarity in dependence of cusp temperature on applied magnetic field. Field dependent maximum of heat capacity is observed in the same magnetic field and temperature range.

Nuclear spin-spin coupling in a van der Waals-bonded system: xenon dimer.

Science.gov (United States)

Vaara, Juha; Hanni, Matti; Jokisaari, Jukka

2013-03-14

Nuclear spin-spin coupling over van der Waals bond has recently been observed via the frequency shift of solute protons in a solution containing optically hyperpolarized (129)Xe nuclei. We carry out a first-principles computational study of the prototypic van der Waals-bonded xenon dimer, where the spin-spin coupling between two magnetically non-equivalent isotopes, J((129)Xe - (131)Xe), is observable. We use relativistic theory at the four-component Dirac-Hartree-Fock and Dirac-density-functional theory levels using novel completeness-optimized Gaussian basis sets and choosing the functional based on a comparison with correlated ab initio methods at the nonrelativistic level. J-coupling curves are provided at different levels of theory as functions of the internuclear distance in the xenon dimer, demonstrating cross-coupling effects between relativity and electron correlation for this property. Calculations on small Xe clusters are used to estimate the importance of many-atom effects on J((129)Xe - (131)Xe). Possibilities of observing J((129)Xe - (131)Xe) in liquid xenon are critically examined, based on molecular dynamics simulation. A simplistic spherical model is set up for the xenon dimer confined in a cavity, such as in microporous materials. It is shown that the on the average shorter internuclear distance enforced by the confinement increases the magnitude of the coupling as compared to the bulk liquid case, rendering J((129)Xe - (131)Xe) in a cavity a feasible target for experimental investigation.

Electron Spin Resonance in CuSO45H2O down to 100 mK

Science.gov (United States)

Kadowaki, Kazuo; Chiba, Yoshiaki; Kindo, Koichi; Date, Muneyuki

1988-12-01

Copper sulfate pentahydrate CuSO45H2O is investigated by ESR at 9, 17, 24, 35 and 50 GHz regions down to about 100 mK using a combined cryostat of 3He and adiabatic demagnetization. The temperature dependent exchange interaction JAB between inequivalent site spins A and B is found. It is about 0.11 K at room temperature and increases with decreasing temperature up to 0.24 K. Temperature dependent resonance shifts are attributed to the exchange shift coming from non-resonant dissimilar spins. Partial order effect below 1 K is discussed.

Spin interference of neutrons tunneling through magnetic thin films

International Nuclear Information System (INIS)

Hino, Masahiro; Achiwa, Norio; Tasaki, Seiji; Ebisawa, Toru; Akiyoshi, Tsunekazu; Kawai, Takeshi.

1996-01-01

Larmor precession of a neutron spin is represented as the superposition of the wave functions of the two Stern-Gerlach states ↑ and ↓. A transverse neutron spin echo (NSE) spectrometer can hence be used as a neutron spin interferometer (NSI) by setting a magnetic film, such as iron and permalloy45 (Fe 55 Ni 45 ), thin enough to permit tunneling at an incident angle above and below the critical angle of the total reflection in the Larmor precession field. The NSI can be used to study spin coherent superposition and rotation of the Larmor precession through a magnetic thin film for a tunneling ↑ spin neutron and a non-tunneling ↓ spin neutron and to get the tunneling time using Larmor clock. The NSI experiments were carried out to measure the shifts of NSE signals transmitted through magnetic iron films with thicknesses of 200 and 400 A and those magnetic permalloy45 films with thicknesses of 200 and 400 A, respectively, as a function of the incident angle. Then even in tunneling ↑ spin neutron and non-tunneling ↓ spin neutron, NSE signal was observed. The phase delay was measured in iron and permalloy45 films with thickness of 200 A, and the tunneling time using Larmor clock was estimated to be 4 ± 0.6 x 10 -9 sec. (author)

Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

Science.gov (United States)

Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

2007-07-27

We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency.

Spin-crossover in [Fe(3-bpp)2][BF4]2 in different solvents--a dramatic stabilisation of the low-spin state in water.

Science.gov (United States)

Barrett, Simon A; Kilner, Colin A; Halcrow, Malcolm A

2011-12-07

The temperature of spin-crossover in [Fe(3-bpp)(2)][BF(4)](2) (3-bpp = 2,6-di{pyrazol-3-yl}pyridine) tends to increase in associating solvents. In particular, T(½) shifts to 60-70 K higher temperature in water compared to organic solvents.

Spin dynamics and Kondo physics in optical tweezers

Science.gov (United States)

Lin, Yiheng; Lester, Brian J.; Brown, Mark O.; Kaufman, Adam M.; Long, Junling; Ball, Randall J.; Isaev, Leonid; Wall, Michael L.; Rey, Ana Maria; Regal, Cindy A.

2016-05-01

We propose to use optical tweezers as a toolset for direct observation of the interplay between quantum statistics, kinetic energy and interactions, and thus implement minimum instances of the Kondo lattice model in systems with few bosonic rubidium atoms. By taking advantage of strong local exchange interactions, our ability to tune the spin-dependent potential shifts between the two wells and complete control over spin and motional degrees of freedom, we design an adiabatic tunneling scheme that efficiently creates a spin-singlet state in one well starting from two initially separated atoms (one atom per tweezer) in opposite spin state. For three atoms in a double-well, two localized in the lowest vibrational mode of each tweezer and one atom in an excited delocalized state, we plan to use similar techniques and observe resonant transfer of two-atom singlet-triplet states between the wells in the regime when the exchange coupling exceeds the mobile atom hopping. Moreover, we argue that such three-atom double-tweezers could potentially be used for quantum computation by encoding logical qubits in collective spin and motional degrees of freedom. Current address: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

Quantum gyroscope based on Berry phase of spins in diamond

Science.gov (United States)

Song, Xuerui; Wang, Liujun; Diao, Wenting; Duan, Chongdi

2018-02-01

Gyroscope is the crucial sensor of the inertial navigation system, there is always high demand to improve the sensitivity and reduce the size of the gyroscopes. Using the NV center electronic spin and nuclear spin qubits in diamond, we introduce the research of new types of quantum gyroscopes based on the Berry phase shifts of the spin states during the rotation of the sensor systems. Compared with the performance of the traditional MEMS gyroscope, the sensitivity of the new types of quantum gyroscopes was highly improved and the spatial resolution was reduced to nano-scale. With the help of micro-manufacturing technology in the semiconductor industry, the quantum gyroscopes introduced here can be further integrated into chip-scale sensors.

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

Science.gov (United States)

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

2014-03-03

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

Spin fluctuations in iron based superconductors probed by NMR relaxation rate

Energy Technology Data Exchange (ETDEWEB)

Graefe, Uwe; Kuehne, Tim; Wurmehl, Sabine; Buechner, Bernd; Grafe, Hans-Joachim [IFW Dresden, Institute for Solid State Research, PF 270116, 01171 Dresden (Germany); Hammerath, Franziska [IFW Dresden, Institute for Solid State Research, PF 270116, 01171 Dresden (Germany); Department of Physics ' ' A. Volta' ' , University of Pavia-CNISM, I-27100 Pavia (Italy); Lang, Guillaume [3LPEM-UPR5, CNRS, ESPCI Paris Tech, 10 Rue Vauquelin, 75005 Paris (France)

2013-07-01

We present {sup 75}As nuclear magnetic resonance (NMR) results in F doped LaOFeAs iron pnictides. In the underdoped superconducting samples, pronounced spin fluctuations lead to a peak in the NMR spin lattice relaxation rate, (T{sub 1}T){sup -1}. The peak shows a typical field dependence that indicates a critical slowing of spin fluctuations: it is reduced in height and shifted to higher temperatures. In contrast, a similar peak in the underdoped magnetic samples at the ordering temperature of the spin density wave does not show such a field dependence. Furthermore, the peak is absent in optimally and overdoped samples, suggesting the absence of strong spin fluctuations. Our results indicate a glassy magnetic ordering in the underdoped samples that is in contrast to the often reported Curie Weiss like increase of spin fluctuations towards T{sub c}. Additional measurements of the linewidth and the spin spin relaxation rate are in agreement with such a glassy magnetic ordering that is most likely competing with superconductivity. Our results will be compared to Co doped BaFe{sub 2}As{sub 2}, where a similar peak in (T{sub 1}T){sup -1} has been observed.

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.

Impurity-induced tuning of quantum-well States in spin-dependent resonant tunneling.

Science.gov (United States)

Kalitsov, Alan; Coho, A; Kioussis, Nicholas; Vedyayev, Anatoly; Chshiev, M; Granovsky, A

2004-07-23

We report exact model calculations of the spin-dependent tunneling in double magnetic tunnel junctions in the presence of impurities in the well. We show that the impurity can tune selectively the spin channels giving rise to a wide variety of interesting and novel transport phenomena. The tunneling magnetoresistance, the spin polarization, and the local current can be dramatically enhanced or suppressed by impurities. The underlying mechanism is the impurity-induced shift of the quantum well states (QWSs), which depends on the impurity potential, impurity position, and the symmetry of the QWS. Copyright 2004 The American Physical Society

Spin Superfluidity and Magnone BEC in He-3

Science.gov (United States)

Bunkov, Yury

2011-03-01

The spin superfluidity -- superfluidity in the magnetic subsystem of a condensed matter -- is manifested as the spontaneous phase-coherent precession of spins first discovered in 1984 in 3 He-B. This superfluid current of spins -- spin supercurrent -- is one more representative of superfluid currents known or discussed in other systems, such as the superfluid current of mass and atoms in superfluid 4 He; superfluid current of electric charge in superconductors; superfluid current of hypercharge in Standard Model of particle physics; superfluid baryonic current and current of chiral charge in quark matter; etc. Spin superfluidity can be described in terms of the Bose condensation of spin waves -- magnons. We discuss different states of magnon superfluidity with different types of spin-orbit coupling: in bulk 3 He-B; magnetically traped `` Q -balls'' at very low temperatures; in 3 He-A and 3 He-B immerged in deformed aerogel; etc. Some effects in normal 3 He can also be treated as a magnetic BEC of fermi liquid. A very similar phenomena can be observed also in a magnetic systems with dinamical frequensy shift, like MnC03 . We will discuss the main experimental signatures of magnons superfluidity: (i) spin supercurrent, which transports the magnetization on a macroscopic distance more than 1 cm long; (ii) spin current Josephson effect which shows interference between two condensates; (iii) spin current vortex -- a topological defect which is an analog of a quantized vortex in superfluids, of an Abrikosov vortex in superconductors, and cosmic strings in relativistic theories; (iv) Goldstone modes related to the broken U (1) symmetry -- phonons in the spin-superfluid magnon gas; etc. For recent review see Yu. M. Bunkov and G. E. Volovik J. Phys. Cond. Matter. 22, 164210 (2010) This work is partly supported by the Ministry of Education and Science of the Russian Federation (contract N 02.740.11.5217).

Turnover of registered nurses in Israel: characteristics and predictors.

Science.gov (United States)

Toren, Orly; Zelker, Revital; Lipschuetz, Michal; Riba, Shoshana; Reicher, Sima; Nirel, Nurit

2012-05-01

In an era of global and local nursing shortages, nursing turnover has negative consequences in terms of diminished quality of care, increased costs and economic losses and decreased job satisfaction. To examine the turnover rate of registered nurses in Israel by assessing the varying degree of turnover between economic sectors, between hospital and community facilities, and/or between types of hospitals; and by examining potential predicting factors of turnover among registered nurses. A national phone survey was undertaken in Israel consisting of a random sampling of registered nurses of working age (up to age 60). The subjects comprised 10% of a national database of 32,000 registered nurses. The turnover rate among working nurses in Israel currently stands at 23%. In addition, 13% of employed nurses have taken a temporary leave of absence for a period greater than 6 months in the past 10 years, most up to 1 year. While job satisfaction rates were relatively high (72%), Professional satisfaction rates were 60% with no significant difference between hospital and community nurses. The turnover rate of registered nurses from a hospital setting to the community was significantly higher (pcommunity registered nurses to hospitals. Predicting factors of turnover were found to be: young age, part-time work, lack of advanced professional education, academic education and low satisfaction with the nursing profession. The shift of nursing workforce is mainly from hospitals to community health settings. There is a need to monitor and understand the characteristics of job and professional satisfaction among hospital nurses in order to implement crucial organizational interventions and retain hospital nursing staffs. Since young nurses, nurses working part time and nurses with no advanced professional and academic education, tend to move more than others, efforts should be targeted at these specific groups. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Observation of the Goos-Haenchen Shift with Neutrons

International Nuclear Information System (INIS)

Haan, Victor-O. de; Plomp, Jeroen; Rekveldt, Theo M.; Kraan, Wicher H.; Well, Ad A. van; Dalgliesh, Robert M.; Langridge, Sean

2010-01-01

The Goos-Haenchen effect is a spatial shift along an interface resulting from an interference effect that occurs for total internal reflection. This phenomenon was suggested by Sir Isaac Newton, but it was not until 1947 that the effect was experimentally observed by Goos and Haenchen. We provide the first direct, absolute, experimental determination of the Goos-Haenchen shift for a particle experiencing a potential well as required by quantum mechanics: namely, wave-particle duality. Here, the particle is a spin-polarized neutron reflecting from a film of magnetized material. We detect the effect through a subtle change in polarization of the neutron. Here, we demonstrate, through experiment and theory, that neutrons do exhibit the Goos-Haenchen effect and postulate that the associated time shift should also be observable.

Superconductivity and spin excitations in orbitally ordered FeSe

Energy Technology Data Exchange (ETDEWEB)

Kreisel, Andreas; Andersen, Brian M. [Niels Bohr Institute, University of Copenhagen (Denmark); Mukherjee, Shantanu [Niels Bohr Institute, University of Copenhagen (Denmark); Dept. of Physics, State University of New York at Binghamton, Binghamton, NY (United States); Hirschfeld, Peter J. [University of Florida, Gainesville, FL (United States)

2016-07-01

We provide a band-structure with low-energy properties consistent with recent photoemission and quantum oscillations measurements on the Fe-based superconductor FeSe, including a mean-field like orbital ordering in the d{sub xz}/d{sub yz} channel, and show that this model also accounts for the temperature dependence of the measured Knight shift and the spin-relaxation rate. An RPA calculation of the dynamical spin susceptibility yields spin excitations which are peaked at wave vector (π,0) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. Furthermore, the superconducting gap structure obtained from spin fluctuation theory exhibits nodes on the electron pockets, consistent with the 'V'-shaped density of states measured by tunneling spectroscopy on this material. The redistribution of spectral weight in the superconducting state creates a (π,0) ''neutron resonance'' as seen in recent experiments. Comparing to various experimental results, we give predictions for further studies.

Knight shift in scandium and its alloys with hafnium and titanium

International Nuclear Information System (INIS)

Chachkhiani, Z.B.; Chechernikov, V.I.; Martynova, L.F.; Nidel'ko, V.I.; Chachkhiani, L.G.; Georgadze, G.S.

1981-01-01

Results of the investigation of NMR on 45 Sc nuclei and magnetic susceptibility of scandium and its solid solutions with titanium and hafnium are presented. It is shown that the existing hybridization of S and d zones in pure scandium and its alloys with titanium and hafnium affects the Knight shift reducing the value of the contact contribution. The temperature behaviour of the Knight shift from the temperature dependence and spin susceptibility of collectivized d electrons [ru

Nuclear spin and isospin excitations

International Nuclear Information System (INIS)

Osterfeld, F.

1992-01-01

A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon is that the measured total Gamow-Teller transition strength in the resonance region is much less than a model-independent sum rule predicts. Two physically different mechanisms have been discussed to explain this so-called quenching of the total Gamow-Teller strength: coupling to subnuclear degrees of freedom in the form of Δ-isobar excitation and ordinary nuclear configuration mixing. Both detailed nuclear structure calculations and extensive analyses of the scattering data suggest that the nuclear configuration mixing effect is the more important quenching mechanism, although subnuclear degrees of freedom cannot be ruled out. The quenching phenomenon occurs for nuclear-spin excitations at low excitation energies (ω∼10--20 MeV) and small-momentum transfers (q≤0.5 fm -1 ). A completely opposite effect is anticipated in the high (ω,q)-transfer region (0≤ω≤500 MeV, 0.5≤q≤3 fm -1 ). The nuclear spin-isospin response might be enhanced due to the attractive pion field inside the nucleus. Charge-exchange reactions at GeV incident energies have been used to study the quasifree peak region and the Δ-resonance region. An interesting result of these experiments is that the Δ excitation in the nucleus is shifted downwards in energy relative to the Δ excitation of the free proton

Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

KAUST Repository

Ortiz Pauyac, Christian

2016-06-19

In the present thesis we introduce the reader to the field of spintronics and explore new phenomena, such as spin transfer torques, spin filtering, and three types of spin-orbit torques, Rashba, spin Hall, and spin swapping, which have emerged very recently and are promising candidates for a new generation of memory devices in computer technology. A general overview of these phenomena is presented in Chap. 1. In Chap. 2 we study spin transfer torques in tunnel junctions in the presence of spin filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives are summarized in Chap. 5.

NMR studies of spin excitations in superconducting Bi2Sr2CaCu2O8+δ single crystals

Science.gov (United States)

Takigawa, M.; Mitzi, D. B.

1994-08-01

The oxygen NMR shift and the Cu nuclear spin-lattice relaxation rate (1/T1) were measured in Bi2.1Sr1.9Ca0.9Cu2.1O8+δ single crystals. While both the shift and 1/(T1T) decrease sharply near Tc, 1/(T1T) becomes nearly constant at low temperatures, indicating a gapless superconducting state with finite density of states at the Fermi level. From the oxygen shift data, the residual spin susceptibility at T=0 is estimated to be 10% of the value at room temperature. Our results are most consistent with a d-wave pairing model with strong (resonant) impurity scattering.

Spin-filtering effect and proximity effect in normal metal/ferromagnetic insulator/normal metal/superconductor junctions

International Nuclear Information System (INIS)

Li Hong; Yang Wei; Yang Xinjian; Qin Minghui; Xu Yihong

2007-01-01

Taking into account the thickness of the ferromagnetic insulator (FI), the spin-filtering effect and proximity effect in normal metal/ferromagnetic insulator/normal metal/superconductor (NM/FI/NM/SC) junctions are studied based on an extended Blonder-Tinkham-Klapwijk (BTK) theory. It is shown that a spin-dependent energy shift during the tunneling process induces splitting of the sub-energy gap conductance peaks and the spin polarization in the ferromagnetic insulator causes an imbalance of the peak heights. Different from the ferromagnet the spin-filtering effect of the FI cannot cause the reversion of the normalized conductance in NM/FI/NM/SC junctions

Electron spin-lattice relaxation in fractals

International Nuclear Information System (INIS)

Shrivastava, K.N.

1986-08-01

We have developed the theory of the spin-fracton interaction for paramagnetic ions in fractal structures. The interaction is exponentially damped by the self-similarity length of the fractal and by the range dimensionality d Φ . The relaxation time of the spin due to the absorption and emission of the fracton has been calculated for a general dimensionality called the Raman dimensionality d R , which for the fractons differs from the Hausdorff (fractal) dimensionality, D, as well as from the Euclidean dimensionality, d. The exponent of the energy level separation in the relaxation rate varies with d R d Φ /D. We have calculated the spin relaxation rate due to a new type of Raman process in which one fracton is absorbed to affect a spin transition from one electronic level to another and later another fracton is emitted along with a spin transition such that the difference in the energies of the two fractons is equal to the electronic energy level separation. The temperature and the dimensionality dependence of such a process has been found in several approximations. In one of the approximations where the van Vleck relaxation rate for a spin in a crystal is known to vary with temperature as T 9 , our calculated variation for fractals turns out to be T 6.6 , whereas the experimental value for Fe 3+ in frozen solutions of myoglobin azide is T 6.3 . Since we used d R =4/3 and the fracton range dimensionality d Φ =D/1.8, we expect to measure the dimensionalities of the problem by measuring the temperature dependence of the relaxation times. We have also calculated the shift of the paramagnetic resonance transition for a spin in a fractal for general dimensionalities. (author)

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.

Measuring the spin Chern number in time-reversal-invariant Hofstadter optical lattices

Energy Technology Data Exchange (ETDEWEB)

Zhang, Dan-Wei, E-mail: zdanwei@126.com [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006 (China); Cao, Shuai, E-mail: shuaicao2004@163.com [Department of Applied Physics, College of Electronic Engineering, South China Agricultural University, Guangzhou 510642 China (China)

2016-10-14

We propose an experimental scheme to directly measure the spin Chern number of the time-reversal-invariant Hofstadter model in optical lattices. We first show that this model can be realized by using ultracold Fermi atoms with two pseudo-spin states encoded by the internal Zeeman states in a square optical lattice and the corresponding topological Bloch bands are characterized by the spin Chern number. We then propose and numerically demonstrate that this topological invariant can be extracted from the shift of the hybrid Wannier center in the optical lattice. By spin-resolved in situ detection of the atomic densities along the transverse direction combined with time-of-flight measurement along another spatial direction, the spin Chern number in this system is directly measured. - Highlights: • The cold-atom optical-lattice scheme for realizing the time-reversal-invariant Hofstadter model is proposed. • The intrinsic spin Chern number related to the hybrid Wannier center in the optical lattice is investigated. • Direct measurement of the spin Chern number in the proposed system is theoretically demonstrated.

Spin-polarized spin excitation spectroscopy

International Nuclear Information System (INIS)

Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J

2010-01-01

We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu 2 N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

Bias-free spin-wave phase shifter for magnonic logic

Energy Technology Data Exchange (ETDEWEB)

Louis, Steven; Tyberkevych, Vasyl; Slavin, Andrei [Department of Physics, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan, 48309–4401 (United States); Lisenkov, Ivan, E-mail: ivan.lisenkov@phystech.edu [Department of Physics, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan, 48309–4401 (United States); Kotelnikov Institute of Radio-engineering and Electronics of RAS, 11–7 Mokhovaya st., Moscow, 125009 (Russian Federation); Nikitov, Sergei [Kotelnikov Institute of Radio-engineering and Electronics of RAS, 11–7 Mokhovaya st., Moscow, 125009 (Russian Federation); Moscow Institute of Physics and Technology, 9 Instituskij per., Dolgoprudny, 141700, Moscow Region (Russian Federation); Department of Physics, Saratov State University, 83 Astrakhanskaya Street, Saratov, 410012 (Russian Federation)

2016-06-15

A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall “waveguide” in a dipolarly-coupled magnetic dot array with a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that the remagnetization of a single magnetic dot adjacent to the domain wall waveguide introduces a controllable phase shift in the propagating spin wave mode without significant change to the mode amplitude. It is also demonstrated that a logic XOR gate can be realized in the same system.

Effects of doping on spin correlations in the periodic Anderson model

International Nuclear Information System (INIS)

Bonca, J.; Gubernatis, J.E.

1998-01-01

We studied the effects of hole doping on spin correlations in the two-dimensional periodic Anderson model, mainly at the full and three-quarters-full lower bands cases. In the full lower band case, strong antiferromagnetic correlations develop when the on-site repulsive interaction strength U becomes comparable to the quasiparticle bandwidth. In the three-quarters full case, a kind of spin correlation develops that is consistent with the resonance between a (π,0) and a (0,π) spin-density wave. In this state the spins on different sublattices appear uncorrelated. Hole doping away from the completely full case rapidly destroys the long-range antiferromagnetic correlations, in a manner reminiscent of the destruction of antiferromagnetism in the Hubbard model. In contrast to the Hubbard model, the doping does not shift the peak in the magnetic structure factor from the (π,π) position. At dopings intermediate to the full and three-quarters full cases, only weak spin correlations exist. copyright 1998 The American Physical Society

Spin crossover behaviour in Hofmann-like coordination polymer Fe(py)2[Pd(CN)4] with 57Fe Mössbauer spectra

Science.gov (United States)

Kitazawa, Takafumi; Kishida, Takanori; Kawasaki, Takeshi; Takahashi, Masashi

2017-11-01

We have prepared the 2D spin crossover complexes Fe(L)2Pd(CN)4 (L = py : 1a; py-D5 : 1b and py-15N : 1c). 1a has been characterised by 57Fe Mossbauer spectroscopic measurements, single crystal X-ray determination and SQUID measurements. The Mössbauer spectra for 1a indicate that the iron(II) spin states are in high spin states at 298 K and are in low spin states at 77 K. The crystal structures of 1a at 298 K and 90 K also show the high spin state and the low spin state respectively, associated with the Fe(II)-N distances. The spin transition temperature range of 1a is higher than that of Fe(py)2Ni(CN)4 since Pd(II) ions are larger and heavier than Ni(II) ions. SQUID data indicate isotope effects among 1a, 1b and 1c are observed in very small shifts of the transition temperatures probably due to larger and heavier Pd(II) ions. The delicate shifts would be associated with subtle balances between different vibrations around Fe(II) atoms and electronic factors.

An elementary quantum network using robust nuclear spin qubits in diamond

Science.gov (United States)

Kalb, Norbert; Reiserer, Andreas; Humphreys, Peter; Blok, Machiel; van Bemmelen, Koen; Twitchen, Daniel; Markham, Matthew; Taminiau, Tim; Hanson, Ronald

Quantum registers containing multiple robust qubits can form the nodes of future quantum networks for computation and communication. Information storage within such nodes must be resilient to any type of local operation. Here we demonstrate multiple robust memories by employing five nuclear spins adjacent to a nitrogen-vacancy defect centre in diamond. We characterize the storage of quantum superpositions and their resilience to entangling attempts with the electron spin of the defect centre. The storage fidelity is found to be limited by the probabilistic electron spin reset after failed entangling attempts. Control over multiple memories is then utilized to encode states in decoherence protected subspaces with increased robustness. Furthermore we demonstrate memory control in two optically linked network nodes and characterize the storage capabilities of both memories in terms of the process fidelity with the identity. These results pave the way towards multi-qubit quantum algorithms in a remote network setting.

Cα chemical shift tensors in helical peptides by dipolar-modulated chemical shift recoupling NMR

International Nuclear Information System (INIS)

Yao Xiaolan; Yamaguchi, Satoru; Hong Mei

2002-01-01

The Cα chemical shift tensors of proteins contain information on the backbone conformation. We have determined the magnitude and orientation of the Cα chemical shift tensors of two peptides with α-helical torsion angles: the Ala residue in G*AL (φ=-65.7 deg., ψ=-40 deg.), and the Val residue in GG*V (φ=-81.5 deg., ψ=-50.7 deg.). The magnitude of the tensors was determined from quasi-static powder patterns recoupled under magic-angle spinning, while the orientation of the tensors was extracted from Cα-Hα and Cα-N dipolar modulated powder patterns. The helical Ala Cα chemical shift tensor has a span of 36 ppm and an asymmetry parameter of 0.89. Its σ 11 axis is 116 deg. ± 5 deg. from the Cα-Hα bond while the σ 22 axis is 40 deg. ± 5 deg. from the Cα-N bond. The Val tensor has an anisotropic span of 25 ppm and an asymmetry parameter of 0.33, both much smaller than the values for β-sheet Val found recently (Yao and Hong, 2002). The Val σ 33 axis is tilted by 115 deg. ± 5 deg. from the Cα-Hα bond and 98 deg. ± 5 deg. from the Cα-N bond. These represent the first completely experimentally determined Cα chemical shift tensors of helical peptides. Using an icosahedral representation, we compared the experimental chemical shift tensors with quantum chemical calculations and found overall good agreement. These solid-state chemical shift tensors confirm the observation from cross-correlated relaxation experiments that the projection of the Cα chemical shift tensor onto the Cα-Hα bond is much smaller in α-helices than in β-sheets

Simultaneous time-optimal control of the inversion of two spin-(1/2) particles

International Nuclear Information System (INIS)

Assemat, E.; Lapert, M.; Sugny, D.; Zhang, Y.; Braun, M.; Glaser, S. J.

2010-01-01

We analyze the simultaneous time-optimal control of two-spin systems. The two noncoupled spins, which differ in the value of their chemical offsets, are controlled by the same magnetic fields. Using an appropriate rotating frame, we restrict the study to the case of opposite shifts. We then show that the optimal solution of the inversion problem in a rotating frame is composed of a pulse sequence of maximum intensity and is similar to the optimal solution for inverting only one spin by using a nonresonant control field in the laboratory frame. An example is implemented experimentally using nuclear magnetic resonance techniques.

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.

Length dependence of rectification in organic co-oligomer spin rectifiers

International Nuclear Information System (INIS)

Hu Gui-Chao; Zhang Zhao; Li Ying; Ren Jun-Feng; Wang Chuan-Kui

2016-01-01

The rectification ratio of organic magnetic co-oligomer diodes is investigated theoretically by changing the molecular length. The results reveal two distinct length dependences of the rectification ratio: for a short molecular diode, the charge-current rectification changes little with the increase of molecular length, while the spin-current rectification is weakened sharply by the length; for a long molecular diode, both the charge-current and spin-current rectification ratios increase quickly with the length. The two kinds of dependence switch at a specific length accompanied with an inversion of the rectifying direction. The molecular ortibals and spin-resolved transmission analysis indicate that the dominant mechanism of rectification suffers a change at this specific length, that is, from asymmetric shift of molecular eigenlevels to asymmetric spatial localization of wave functions upon the reversal of bias. This work demonstrates a feasible way to control the rectification in organic co-oligomer spin diodes by adjusting the molecular length. (paper)

Precise determination of lattice phase shifts and mixing angles

Energy Technology Data Exchange (ETDEWEB)

Lu, Bing-Nan, E-mail: b.lu@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Lähde, Timo A. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Lee, Dean [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Meißner, Ulf-G. [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA – High Performance Computing, Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-09-10

We introduce a general and accurate method for determining lattice phase shifts and mixing angles, which is applicable to arbitrary, non-cubic lattices. Our method combines angular momentum projection, spherical wall boundaries and an adjustable auxiliary potential. This allows us to construct radial lattice wave functions and to determine phase shifts at arbitrary energies. For coupled partial waves, we use a complex-valued auxiliary potential that breaks time-reversal invariance. We benchmark our method using a system of two spin-1/2 particles interacting through a finite-range potential with a strong tensor component. We are able to extract phase shifts and mixing angles for all angular momenta and energies, with precision greater than that of extant methods. We discuss a wide range of applications from nuclear lattice simulations to optical lattice experiments.

Observation of the Goos-Hänchen shift with neutrons.

Science.gov (United States)

de Haan, Victor-O; Plomp, Jeroen; Rekveldt, Theo M; Kraan, Wicher H; van Well, Ad A; Dalgliesh, Robert M; Langridge, Sean

2010-01-08

The Goos-Hänchen effect is a spatial shift along an interface resulting from an interference effect that occurs for total internal reflection. This phenomenon was suggested by Sir Isaac Newton, but it was not until 1947 that the effect was experimentally observed by Goos and Hänchen. We provide the first direct, absolute, experimental determination of the Goos-Hänchen shift for a particle experiencing a potential well as required by quantum mechanics: namely, wave-particle duality. Here, the particle is a spin-polarized neutron reflecting from a film of magnetized material. We detect the effect through a subtle change in polarization of the neutron. Here, we demonstrate, through experiment and theory, that neutrons do exhibit the Goos-Hänchen effect and postulate that the associated time shift should also be observable.

Quantum criticality among entangled spin chains

Science.gov (United States)

Blanc, N.; Trinh, J.; Dong, L.; Bai, X.; Aczel, A. A.; Mourigal, M.; Balents, L.; Siegrist, T.; Ramirez, A. P.

2018-03-01

An important challenge in magnetism is the unambiguous identification of a quantum spin liquid1,2, of potential importance for quantum computing. In such a material, the magnetic spins should be fluctuating in the quantum regime, instead of frozen in a classical long-range-ordered state. While this requirement dictates systems3,4 wherein classical order is suppressed by a frustrating lattice5, an ideal system would allow tuning of quantum fluctuations by an external parameter. Conventional three-dimensional antiferromagnets can be tuned through a quantum critical point—a region of highly fluctuating spins—by an applied magnetic field. Such systems suffer from a weak specific-heat peak at the quantum critical point, with little entropy available for quantum fluctuations6. Here we study a different type of antiferromagnet, comprised of weakly coupled antiferromagnetic spin-1/2 chains as realized in the molecular salt K2PbCu(NO2)6. Across the temperature-magnetic field boundary between three-dimensional order and the paramagnetic phase, the specific heat exhibits a large peak whose magnitude approaches a value suggestive of the spinon Sommerfeld coefficient of isolated quantum spin chains. These results demonstrate an alternative approach for producing quantum matter via a magnetic-field-induced shift of entropy from one-dimensional short-range order to a three-dimensional quantum critical point.

Spin current evolution in the separated spin-up and spin-down quantum hydrodynamics

International Nuclear Information System (INIS)

Trukhanova, Mariya Iv.

2015-01-01

We have developed a method of quantum hydrodynamics (QHD) that describes particles with spin-up and with spin-down in separate. We have derived the equation of the spin current evolution as a part of the set of the quantum hydrodynamics equations that treat particles with different projection of spin on the preferable direction as two different species. We have studied orthogonal propagation of waves in the external magnetic field and determined the contribution of quantum corrections due to the Bohm potential and to magnetization energy of particles with different projections of spin in the spin-current wave dispersion. We have analyzed the limits of weak and strong magnetic fields. - Highlights: • We derive the spin current equation for particles with different projection of spin. • We predict the contribution of Bohm potential to the dynamics of spin current. • We derive the spin-current wave in the system of spin-polarized particles. • We study the propagation of spin-acoustic wave in magnetized dielectrics.

Toward nonlinear magnonics: Intensity-dependent spin-wave switching in insulating side-coupled magnetic stripes

Science.gov (United States)

Sadovnikov, A. V.; Odintsov, S. A.; Beginin, E. N.; Sheshukova, S. E.; Sharaevskii, Yu. P.; Nikitov, S. A.

2017-10-01

We demonstrate that the nonlinear spin-wave transport in two laterally parallel magnetic stripes exhibit the intensity-dependent power exchange between the adjacent spin-wave channels. By the means of Brillouin light scattering technique, we investigate collective nonlinear spin-wave dynamics in the presence of magnetodipolar coupling. The nonlinear intensity-dependent effect reveals itself in the spin-wave mode transformation and differential nonlinear spin-wave phase shift in each adjacent magnetic stripe. The proposed analytical theory, based on the coupled Ginzburg-Landau equations, predicts the geometry design involving the reduction of power requirement to the all-magnonic switching. A very good agreement between calculation and experiment was found. In addition, a micromagnetic and finite-element approach has been independently used to study the nonlinear behavior of spin waves in adjacent stripes and the nonlinear transformation of spatial profiles of spin-wave modes. Our results show that the proposed spin-wave coupling mechanism provides the basis for nonlinear magnonic circuits and opens the perspectives for all-magnonic computing architecture.

Long-range interactions in antiferromagnetic quantum spin chains

Science.gov (United States)

Bravo, B.; Cabra, D. C.; Gómez Albarracín, F. A.; Rossini, G. L.

2017-08-01

We study the role of long-range dipolar interactions on antiferromagnetic spin chains, from the classical S →∞ limit to the deep quantum case S =1 /2 , including a transverse magnetic field. To this end, we combine different techniques such as classical energy minima, classical Monte Carlo, linear spin waves, bosonization, and density matrix renormalization group (DMRG). We find a phase transition from the already reported dipolar ferromagnetic region to an antiferromagnetic region for high enough antiferromagnetic exchange. Thermal and quantum fluctuations destabilize the classical order before reaching magnetic saturation in both phases, and also close to zero field in the antiferromagnetic phase. In the extreme quantum limit S =1 /2 , extensive DMRG computations show that the main phases remain present with transition lines to saturation significatively shifted to lower fields, in agreement with the bosonization analysis. The overall picture maintains a close analogy with the phase diagram of the anisotropic XXZ spin chain in a transverse field.

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.

Basic mode of nonlinear spin-wave resonance in normally magnetized ferrite films

International Nuclear Information System (INIS)

Gulyaev, Yu.V.; Zil'berman, P.E.; Timiryazev, A.G.; Tikhomirova, M.P.

2000-01-01

Modes of nonlinear and spin-wave resonance (SWR) in the normally magnetized ferrite films were studied both theoretically and experimentally. The particular emphasis was placed on the basic mode of SWR. One showed theoretically that with the growth of the precession amplitude the profile of the basic mode changed. The nonlinear shift of the resonance field depends on the parameters of fixing of the surface spins. Films of ferroyttrium garnet (FYG) with strong gradient of the single-axis anisotropy field along the film thickness, as well as, FYG films of the submicron thickness where investigated experimentally. With the intensification of Uhf-power one observed the sublinear shift of the basic mode resonance field following by the superlinear growth of the absorbed power. That kind of behaviour is explained by variation of the profile of the varying magnetization space distribution [ru

Exchange anisotropy pinning of a standing spin-wave mode

Science.gov (United States)

Magaraggia, R.; Kennewell, K.; Kostylev, M.; Stamps, R. L.; Ali, M.; Greig, D.; Hickey, B. J.; Marrows, C. H.

2011-02-01

Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin-wave thickness mode in Ni80Fe20/Ir25Mn75 exchange-biased bilayers was studied for a range of Ir25Mn75 thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique “fingerprint” of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet-antiferromagnet interface anisotropy. Thermal effects are studied for ultrathin antiferromagnetic Ir25Mn75 thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

Dynamical control of Mn spin-system cooling by photogenerated carriers in a (Zn,Mn)Se/BeTe heterostructure

Science.gov (United States)

Debus, J.; Maksimov, A. A.; Dunker, D.; Yakovlev, D. R.; Tartakovskii, I. I.; Waag, A.; Bayer, M.

2010-08-01

The magnetization dynamics of the Mn spin system in an undoped (Zn,Mn)Se/BeTe type-II quantum well was studied by a time-resolved pump-probe photoluminescence technique. The Mn spin temperature was evaluated from the giant Zeeman shift of the exciton line in an external magnetic field of 3 T. The relaxation dynamics of the Mn spin temperature to the equilibrium temperature of the phonon bath after the pump-laser-pulse heating can be accelerated by the presence of free electrons. These electrons, generated by a control laser pulse, mediate the spin and energy transfer from the Mn spin system to the lattice and bypass the relatively slow direct spin-lattice relaxation of the Mn ions.

Enhanced spin Hall effect of tunneling light in hyperbolic metamaterial waveguide.

Science.gov (United States)

Tang, Tingting; Li, Chaoyang; Luo, Li

2016-08-01

Giant enhancement of spin Hall effect of tunneling light (SHETL) is theoretically proposed in a frustrated total internal reflection (FTIR) structure with hyperbolic metamaterial (HMM). We calculate the transverse shift of right-circularly polarized light in a SiO2-air-HMM-air-SiO2 waveguide and analyze the physical mechanism of the enhanced SHETL. The HMM anisotropy can greatly increase the transverse shift of polarized light even though HMM loss might reduce it. Compared with transverse shift of transmitted light through a single HMM slab with ZnAlO/ZnO multilayer, the maximum transverse shift of tunneling light through a FTIR structure with identical HMM can be significantly enlarged by more than three times which reaches -38 μm without any amplification method.

Spin drift and spin diffusion currents in semiconductors

Energy Technology Data Exchange (ETDEWEB)

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

2008-09-15

On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

Spin drift and spin diffusion currents in semiconductors

Directory of Open Access Journals (Sweden)

M Idrish Miah

2008-01-01

Full Text Available On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

Spin drift and spin diffusion currents in semiconductors

International Nuclear Information System (INIS)

Idrish Miah, M

2008-01-01

On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

Energy levels and electron g-factor of spherical quantum dots with Rashba spin-orbit interaction

International Nuclear Information System (INIS)

Vaseghi, B.; Rezaei, G.; Malian, M.

2011-01-01

We have studied simultaneous effects of Rashba spin-orbit interaction and external electric and magnetic fields on the subbands energy levels and electron g-factor of spherical quantum dots. It is shown that energy eigenvalues strongly depend on the combined effects of external electric and magnetic fields and spin-orbit interaction strength. The more the spin-orbit interaction strength increase, the more the energy eigenvalues increase. Also, we found that the electron g-factor sensitively differers from the bulk value due to the confinement effects. Furthermore, external fields and spin-orbit interaction have a great influence on this important quantity. -- Highlights: → Energy of spherical quantum dots depends on the spin-orbit interaction strength in external electric and magnetic fields. → Spin-orbit interaction shifts the energy levels. → Electron g-factor differs from the bulk value in spherical quantum dots due to the confinement effects. → Electron g-factor strongly depends on the spin-orbit interaction strength in external electric and magnetic fields.

Spin Polarization Oscillations without Spin Precession: Spin-Orbit Entangled Resonances in Quasi-One-Dimensional Spin Transport

Directory of Open Access Journals (Sweden)

D. H. Berman

2014-03-01

Full Text Available Resonant behavior involving spin-orbit entangled states occurs for spin transport along a narrow channel defined in a two-dimensional electron gas, including an apparent rapid relaxation of the spin polarization for special values of the channel width and applied magnetic field (so-called ballistic spin resonance. A fully quantum-mechanical theory for transport using multiple subbands of the one-dimensional system provides the dependence of the spin density on the applied magnetic field and channel width and position along the channel. We show how the spatially nonoscillating part of the spin density vanishes when the Zeeman energy matches the subband energy splittings. The resonance phenomenon persists in the presence of disorder.

Laser-assisted spin-polarized transport in graphene tunnel junctions

International Nuclear Information System (INIS)

Ding Kaihe; Zhu Zhengang; Berakdar, Jamal

2012-01-01

The Keldysh nonequilibrium Green’s function method is utilized to theoretically study spin-polarized transport through a graphene spin valve irradiated by a monochromatic laser field. It is found that the bias dependence of the differential conductance exhibits successive peaks corresponding to the resonant tunneling through the photon-assisted sidebands. The multi-photon processes originate from the combined effects of the radiation field and the graphene tunneling properties, and are shown to be substantially suppressed in a graphene spin valve which results in a decrease of the differential conductance for a high bias voltage. We also discuss the appearance of a dynamical gap around zero bias due to the radiation field. The gap width can be tuned by changing the radiation electric field strength and the frequency. This leads to a shift of the resonant peaks in the differential conductance. We also demonstrate numerically the dependences of the radiation and spin valve effects on the parameters of the external fields and those of the electrodes. We find that the combined effects of the radiation field, the graphene and the spin valve properties bring about an oscillatory behavior in the tunnel magnetoresistance, and this oscillatory amplitude can be changed by scanning the radiation field strength and/or the frequency. (paper)

Effect of spin rotation coupling on spin transport

International Nuclear Information System (INIS)

Chowdhury, Debashree; Basu, B.

2013-01-01

We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k → ⋅p → perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k → ⋅p → framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied

Effect of spin rotation coupling on spin transport

Energy Technology Data Exchange (ETDEWEB)

Chowdhury, Debashree, E-mail: debashreephys@gmail.com; Basu, B., E-mail: sribbasu@gmail.com

2013-12-15

We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k{sup →}⋅p{sup →} perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k{sup →}⋅p{sup →} framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied.

A Scandinavian Experience of Register Collaboration: The Nordic Arthroplasty Register Association (NARA)

DEFF Research Database (Denmark)

Havelin, Leif I; Robertsson, Otto; Fenstad, Anne M

2011-01-01

The Nordic (Scandinavian) countries have had working arthroplasty registers for several years. However, the small numbers of inhabitants and the conformity within each country with respect to preferred prosthesis brands and techniques have limited register research.......The Nordic (Scandinavian) countries have had working arthroplasty registers for several years. However, the small numbers of inhabitants and the conformity within each country with respect to preferred prosthesis brands and techniques have limited register research....

Determination of the knight shift in liquid alloys of silver with lanthanides by stroboscopic observation of perturbed angular correlations according to the reaction 109Ag(p,n)109Cd

International Nuclear Information System (INIS)

Gundelfinger, F.

1975-01-01

In liquid alloys of the composition Agsub(1-x)Rsub(x) (0 109 Ag(p,n) 109 Cd* induced by 10 MeV protons. In first appoximation, the values found for the relative change of knight shift prove to be proportional to the negative z-component of the 4f-shell spin of the respective lanthanide metals. The major part of the knight shift is produced by the spin polarization of the conduction electrons due to coupling to the spins of the lanthanide ions. The possible coupling mechanisms are discussed. (orig./GSC) [de

Shift work, fetal development and course of pregnancy.

Science.gov (United States)

Nurminen, T

1989-12-01

Information on 1475 mothers of infants with selected structural malformations and an equal number of mothers of "normal" babies was analyzed for a possible relationship between shift work and adverse pregnancy outcome or a complicated course of pregnancy. The primary data were obtained from the Finnish Register of Congenital Malformations supplemented by special interviews on the mothers' work conditions. No signs of a teratogenic risk were observed. The relationship between course of pregnancy and outcomes other than malformations was determined from the noncase mothers' experience. Threatened abortion and pregnancy-induced hypertension were not associated with rotating shift work alone, but in a noisy work environment moderate risks could not be ruled out. Rotating shift work was associated with a slight excess of babies small for their gestational age independently of noise exposure. The results suggest that further studies on the effects of different work schedules on pregnancy are worth consideration.

Arthroplasty register for Germany

Directory of Open Access Journals (Sweden)

Hagen, Anja

2009-10-01

Full Text Available Scientific background: The annual number of joint replacement operations in Germany is high. The introduction of an arthroplasty register promises an important contribution to the improvement of the quality of patient’s care. Research questions: The presented report addresses the questions on organization and functioning, benefits and cost-benefits as well as on legal, ethical and social aspects of the arthroplasty registers. Methods: A systematic literature search was conducted in September 2008 in the medical databases MEDLINE, EMBASE etc. and was complemented with a hand search. Documents describing arthroplasty registers and/or their relevance as well as papers on legal, ethical and social aspects of such registers were included in the evaluation. The most important information was extracted and analysed. Results: Data concerning 30 arthroplasty registers in 19 countries as well as one international arthroplasty register were identified. Most of the arthroplasty registers are maintained by national orthopedic societies, others by health authorities or by their cooperation. Mostly, registries are financially supported by governments and rarely by other sources.The participation of the orthopedists in the data collection process of the arthroplasty registry is voluntary in most countries. The consent of the patients is usually required. The unique patient identification is ensured in nearly all registers.Each data set consists of patient and clinic identification numbers, data on diagnosis, the performed intervention, the operation date and implanted prostheses. The use of clinical scores, patient-reported questionnaires and radiological documentation is rare. Methods for data documentation and transfer are paper form, electronic entry as well as scanning of the data using bar codes. The data are mostly being checked for their completeness and validity. Most registers offer results of the data evaluation to the treating orthopedists and

Resolution of NMR chemical shift images into real and imaginary components

International Nuclear Information System (INIS)

Yamamoto, E.; Kohno, H.

1986-01-01

Fast chemical shift imaging of two-line materials is described using a modified spin-echo sequence. The method resolves the two chemical shift images into real and imaginary components representing the reconstructed image. The measuring time is reduced to half of that for the conventional method proposed by Dixon et al, and quantitative evaluation of the images becomes possible. Reference material with a single resonant line is used to eliminate the phase error caused by static field inhomogeneity and the inherent apparatus offset phase. Experiments are conducted using acetone and benzene with a medium-bore superconductive magnet operating at 0.5T. From these experiments, two chemical shift images are obtained. These images are then superimposed to produce a conventional density image. (author)

Electrical Initialization of Electron and Nuclear Spins in a Single Quantum Dot at Zero Magnetic Field.

Science.gov (United States)

Cadiz, Fabian; Djeffal, Abdelhak; Lagarde, Delphine; Balocchi, Andrea; Tao, Bingshan; Xu, Bo; Liang, Shiheng; Stoffel, Mathieu; Devaux, Xavier; Jaffres, Henri; George, Jean-Marie; Hehn, Michel; Mangin, Stephane; Carrere, Helene; Marie, Xavier; Amand, Thierry; Han, Xiufeng; Wang, Zhanguo; Urbaszek, Bernhard; Lu, Yuan; Renucci, Pierre

2018-04-11

The emission of circularly polarized light from a single quantum dot relies on the injection of carriers with well-defined spin polarization. Here we demonstrate single dot electroluminescence (EL) with a circular polarization degree up to 35% at zero applied magnetic field. The injection of spin-polarized electrons is achieved by combining ultrathin CoFeB electrodes on top of a spin-LED device with p-type InGaAs quantum dots in the active region. We measure an Overhauser shift of several microelectronvolts at zero magnetic field for the positively charged exciton (trion X + ) EL emission, which changes sign as we reverse the injected electron spin orientation. This is a signature of dynamic polarization of the nuclear spins in the quantum dot induced by the hyperfine interaction with the electrically injected electron spin. This study paves the way for electrical control of nuclear spin polarization in a single quantum dot without any external magnetic field.

Solutions of the Dirac Equation with the Shifted DENG-FAN Potential Including Yukawa-Like Tensor Interaction

Science.gov (United States)

Yahya, W. A.; Falaye, B. J.; Oluwadare, O. J.; Oyewumi, K. J.

2013-08-01

By using the Nikiforov-Uvarov method, we give the approximate analytical solutions of the Dirac equation with the shifted Deng-Fan potential including the Yukawa-like tensor interaction under the spin and pseudospin symmetry conditions. After using an improved approximation scheme, we solved the resulting schr\\"{o}dinger-like equation analytically. Numerical results of the energy eigenvalues are also obtained, as expected, the tensor interaction removes degeneracies between spin and pseudospin doublets.

Production and Detection of Spin-Entangled Electrons in Mesoscopic Conductors

Science.gov (United States)

Burkard, Guido

2006-03-01

Electron spins are an extremely versatile form of quantum bits. When localized in quantum dots, they can form a register for quantum computation. Moreover, being attached to a charge in a mesoscopic conductor allows the electron spin to play the role of a mobile carrier of quantum information similarly to photons in optical quantum communication. Since entanglement is a basic resource in quantum communication, the production and detection of spin-entangled Einstein-Podolsky-Rosen (EPR) pairs of electrons are of great interest. Besides the practical importance, it is of fundamental interest to test quantum non-locality for electrons. I review the theoretical schemes for the entanglement production in superconductor-normal junctions [1] and other systems. The electron spin entanglement can be detected and quantified from measurements of the fluctuations (shot noise) of the charge current after the electrons have passed through an electronic beam splitter [2,3]. This two-particle interference effect is related to the Hanbury-Brown and Twiss experiment and leads to a doubling of the shot noise SI=φ=0 for spin-entangled states, allowing their differentiation from unentangled pairs. I report on the role of spin-orbit coupling (Rashba and Dresselhaus) in a complete characterization of the spin entanglement [4]. Finally, I address the effects of a discrete level spectrum in the mesoscopic leads and of backscattering and decoherence.[1] P. Recher, E. V. Sukhorukov, D. Loss, Phys. Rev. B 63, 165314 (2001)[2] G. Burkard, D. Loss, E. V. Sukhorukov, Phys. Rev. B 61, R16303 (2000)[3] G. Burkard and D. Loss, Phys. Rev. Lett.91, 087903 (2003)[4] J. C. Egues, G. Burkard, D. Saraga, J. Schliemann, D. Loss, cond-mat/0509038, to appear in Phys.Rev.B (2005).

Goos–Hänchen and Imbert–Fedorov beam shifts: an overview

International Nuclear Information System (INIS)

Bliokh, K Y; Aiello, A

2013-01-01

We consider reflection and transmission of polarized paraxial light beams at a plane dielectric interface. The field transformations taking into account a finite beam width are described based on the plane-wave representation and geometric rotations. Using geometrical-optics coordinate frames accompanying the beams, we construct an effective Jones matrix characterizing spatial-dispersion properties of the interface. This results in a unified self-consistent description of the Goos–Hänchen and Imbert–Fedorov shifts (the latter being also known as the spin Hall effect of light). Our description reveals the intimate relation of the transverse Imbert–Fedorov shift to the geometric phases between constituent waves in the beam spectrum and to the angular momentum conservation for the whole beam. Both spatial and angular shifts are considered as well as their analogues for higher-order vortex beams carrying intrinsic orbital angular momentum. We also give a brief overview of various extensions and generalizations of the basic beam-shift phenomena and related effects. (review article)

Phase control of spin waves based on a magnetic defect in a one-dimensional magnonic crystal

Science.gov (United States)

Baumgaertl, Korbinian; Watanabe, Sho; Grundler, Dirk

2018-04-01

Magnonic crystals are interesting for spin-wave based data processing. We investigate one-dimensional magnonic crystals (1D MCs) consisting of bistable Co 20 Fe 60 B 20 nanostripes separated by 75 nm wide air gaps. By adjusting the magnetic history, we program a single stripe of opposed magnetization in an otherwise saturated 1D MC. Its influence on propagating spin waves is studied via broadband microwave spectroscopy. Depending on an in-plane bias magnetic field, we observe spin wave phase shifts of up to almost π and field-controlled attenuation attributed to the reversed nanostripe. Our findings are of importance for magnetologics, where the control of spin wave phases is essential.

Superconductivity and spin excitations in orbitally ordered FeSe

Science.gov (United States)

Kreisel, Andreas; Mukherjee, Shantanu; Hirschfeld, P. J.; Andersen, B. M.

We provide a band-structure with low-energy properties consistent with recent photoemission and quantum oscillations measurements on the Fe-based superconductor FeSe, including a mean-field like orbital ordering in the dxz /dyz channel, and show that this model also accounts for the temperature dependence of the measured Knight shift and the spin-relaxation rate. An RPA calculation of the dynamical spin susceptibility yields spin excitations which are peaked at wave vector (π , 0) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. Furthermore, the superconducting gap structure obtained from spin fluctuation theory exhibits nodes on the electron pockets, consistent with the 'V'-shaped density of states measured by tunneling spectroscopy on this material. The redistribution of spectral weight in the superconducting state creates a (π , 0) ''neutron resonance'' as seen in recent experiments. Comparing to various experimental results, we give predictions for further studies A.K. and B.M.A. acknowledge financial support from a Lundbeckfond fellowship (Grant No. A9318). P.J.H. was partially supported by the Department of Energy under Grant No. DE-FG02-05ER46236.

Electron spin from self interaction

International Nuclear Information System (INIS)

Spavieri, G.

1992-01-01

The author explores the possibility that the electron self-interaction is the origin of the spin and of the radiative effects of QED. The electron is conceived as a charged, massless, point particle with a quantum or stochastic, internal motion about its center of mass and bound by a self-interaction potential. The hydrodynamic equations of motion describing the electron in its center of mass frame are related to non-Markovian stochastic equations recently used to derive the Schroedinger equation. By averaging over this stochastic internal motion and identifying the energy with the rest mass energy, the angular momentum exhibits properties characteristic of spin. The electromagnetic self-interactions added to the Hamiltonian of the particle correct the g factor to yield the anomalous value (g-2)/2 ∼ 1159.7(2.3) X 10 -6 in agreement with experiment. Calculations of other open-quotes radiativeclose quotes effects including the Lamb shift are presented. The results obtained are finite and suggest that the QED corrections attributed to radiative effects could be obtained classically, i.e., without second quantization and renormalization, by complementing the Dirac theory with this self-interaction mechanism. The g factor dependence on the external magnetic field of this and other spin models is compared with that of QED, showing that these theories can be tested by the present precision measurements of the g factor. 33 refs., 2 tabs

Spin Hall and spin swapping torques in diffusive ferromagnets

KAUST Repository

Pauyac, C. O.

2017-12-08

A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.

Spin Hall and spin swapping torques in diffusive ferromagnets

KAUST Repository

Pauyac, C. O.; Chshiev, M.; Manchon, Aurelien; Nikolaev, S. A.

2017-01-01

A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.

Nuclear spin relaxation in a spin-1/2 antiferromagnetic Heisenberg chain at high fields

International Nuclear Information System (INIS)

Lyo, S.K.

1981-01-01

The proton spin relaxation rate is calculated in the one-dimensional spin-1/2 Heisenberg antiferromagnet α-bis (N-methylsalicylaldiminato)-copper (II), α-CuNSal by using a fermion representation for magnons above the critical field where the magnon spectrum develops a gap. The one-magnon process which is dominant below the critical field is shown to be absent in the presence of a gap in contrast to a previous theory. Instead, we find that the three-magnon rate is large enough to explain the data at low fields. The two-magnon off-resonance damping which enters the expression for the three-magnon rate is calculated by solving the two-magnon scattering exactly, leading to a much smaller value of the rate than that predicted by the Born approximation. Also, in an unsuccessful attempt to resolve the discrepancy between the recently calculated two-magnon rate (dominant at high fields) and the data of α-CuNSal reported by Azevedo et al., we carry out the vertex correction for the spin-density correlation function by summing the RPA series as well as the exchange ladders for the polarization part. We find that, although the exchange enhancement is significantly large, it is nearly canceled out by the RPA correction, and the net effect of the vertex correction is small. This result agrees with the recent data of the similar spin-1/2 antiferromagnetic Heisenberg chain system CuSO 4 x5H 2 O reported by Groen et al. On the other hand, it disagrees with a recent calculation of the two-magnon rate based on a boson representation of spins. To resolve this discrepancy we examine the effect of the boson self-energy correction on the two-magnon rate. The boson spectral shift is found to be quite large in the region where the cited two-boson rate deviates from the two-fermion rate. As a result the two-boson rate is significantly reduced, leading to reasonable agreement with the two-fermion rate

Spin-orbit and spin-lattice coupling

International Nuclear Information System (INIS)

Bauer, Gerrit E.W.; Ziman, Timothy; Mori, Michiyasu

2014-01-01

We pursued theoretical research on the coupling of electron spins in the condensed matter to the lattice as mediated by the spin-orbit interaction with special focus on the spin and anomalous Hall effects. (author)

Study: Long nursing shifts linked to burnout, job dissatisfaction, negative patient assessments.

Science.gov (United States)

2013-02-01

While nurses often choose to work 12-hour shifts, there is new evidence that too many of these longer shifts can lead to burnout and job dissatisfaction. Further, a new study suggests that patients are less satisfied with their care when nurses are working longer shifts, and patient outcomes may suffer as well. Experts recommend education around this issue for both staff nurses and nurse managers, and they urge administrators to devise sensible scheduling solutions. A three-year study, involving 23,000 registered nurses from four states, showed that nurses working shifts of 10 hours or longer were up to two and a half times more likely to experience burnout and dissatisfaction with their jobs than nurses working shorter shifts. Also, the study showed that seven out of 10 patient outcomes were adversely impacted by the longest nursing shifts. The Cleveland Clinic's 'parent shift' gives nurses the option of working shifts of six hours or less in exchange for less pay and no benefits. Administrators use these nurses to help their units manage busy hours or patient surges.

Spin rotation after a spin-independent scattering. Spin properties of an electron gas in a solid

International Nuclear Information System (INIS)

Zayets, V.

2014-01-01

It is shown that spin direction of an electron may not be conserved after a spin-independent scattering. The spin rotations occur due to a quantum-mechanical fact that when a quantum state is occupied by two electrons of opposite spins, the total spin of the state is zero and the spin direction of each electron cannot be determined. It is shown that it is possible to divide all conduction electrons into two group distinguished by their time-reversal symmetry. In the first group the electron spins are all directed in one direction. In the second group there are electrons of all spin directions. The number of electrons in each group is conserved after a spin-independent scattering. This makes it convenient to use these groups for the description of the magnetic properties of conduction electrons. The energy distribution of spins, the Pauli paramagnetism and the spin distribution in the ferromagnetic metals are described within the presented model. The effects of spin torque and spin-torque current are described. The origin of spin-transfer torque is explained within the presented model

Spin injection and spin accumulation in all-metal mesoscopic spin valves

NARCIS (Netherlands)

Jedema, FJ; Nijboer, MS; Filip, AT; van Wees, BJ

2003-01-01

We study the electrical injection and detection of spin accumulation in lateral ferromagnetic-metal-nonmagnetic-metal-ferromagnetic-metal (F/N/F) spin valve devices with transparent interfaces. Different ferromagnetic metals, Permalloy (Py), cobalt (Co), and nickel (Ni), are used as electrical spin

The susceptibilities in the spin-S Ising model

International Nuclear Information System (INIS)

Ainane, A.; Saber, M.

1995-08-01

The susceptibilities of the spin-S Ising model are evaluated using the effective field theory introduced by Tucker et al. for studying general spin-S Ising model. The susceptibilities are studied for all spin values from S = 1/2 to S = 5/2. (author). 12 refs, 4 figs

Control of electron spin decoherence in nuclear spin baths

Science.gov (United States)

Liu, Ren-Bao

2011-03-01

Nuclear spin baths are a main mechanism of decoherence of spin qubits in solid-state systems, such as quantum dots and nitrogen-vacancy (NV) centers of diamond. The decoherence results from entanglement between the electron and nuclear spins, established by quantum evolution of the bath conditioned on the electron spin state. When the electron spin is flipped, the conditional bath evolution is manipulated. Such manipulation of bath through control of the electron spin not only leads to preservation of the center spin coherence but also demonstrates quantum nature of the bath. In an NV center system, the electron spin effectively interacts with hundreds of 13 C nuclear spins. Under repeated flip control (dynamical decoupling), the electron spin coherence can be preserved for a long time (> 1 ms) . Thereforesomecharacteristicoscillations , duetocouplingtoabonded 13 C nuclear spin pair (a dimer), are imprinted on the electron spin coherence profile, which are very sensitive to the position and orientation of the dimer. With such finger-print oscillations, a dimer can be uniquely identified. Thus, we propose magnetometry with single-nucleus sensitivity and atomic resolution, using NV center spin coherence to identify single molecules. Through the center spin coherence, we could also explore the many-body physics in an interacting spin bath. The information of elementary excitations and many-body correlations can be extracted from the center spin coherence under many-pulse dynamical decoupling control. Another application of the preserved spin coherence is identifying quantumness of a spin bath through the back-action of the electron spin to the bath. We show that the multiple transition of an NV center in a nuclear spin bath can have longer coherence time than the single transition does, when the classical noises due to inhomogeneous broadening is removed by spin echo. This counter-intuitive result unambiguously demonstrates the quantumness of the nuclear spin bath

Magnetocaloric effect in quantum spin-s chains

Directory of Open Access Journals (Sweden)

A. Honecker

2009-01-01

Full Text Available We compute the entropy of antiferromagnetic quantum spin-s chains in an external magnetic field using exact diagonalization and Quantum Monte Carlo simulations. The magnetocaloric effect, i. e., temperature variations during adiabatic field changes, can be derived from the isentropes. First, we focus on the example of the spin-s=1 chain and show that one can cool by closing the Haldane gap with a magnetic field. We then move to quantum spin-s chains and demonstrate linear scaling with s close to the saturation field. In passing, we propose a new method to compute many low-lying excited states using the Lanczos recursion.

Graphene spin diode: Strain-modulated spin rectification

Energy Technology Data Exchange (ETDEWEB)

Wang, Yunhua; Wang, B., E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [Sino-French Institute of Nuclear Engineering and Technology, School of Physics and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); Liu, Yulan, E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [School of Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2014-08-04

Strain effects on spin transport in a ferromagnetic/strained/normal graphene junction are explored theoretically. It is shown that the spin-resolved Fermi energy range can be controlled by the armchair direction strain because the strain-induced pseudomagnetic field suppresses the current. The spin rectification effect for the bias reversal occurs because of a combination of ferromagnetic exchange splitting and the broken spatial symmetry of the junction. In addition, the spin rectification performance can be tuned remarkably by manipulation of the strains. In view of this strain-modulated spin rectification effect, we propose that the graphene-based ferromagnetic/strained/normal junction can be used as a tunable spin diode.

Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

KAUST Repository

Ortiz Pauyac, Christian

2016-01-01

filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives

Registered error between PET and CT images confirmed by a water model

International Nuclear Information System (INIS)

Chen Yangchun; Fan Mingwu; Xu Hao; Chen Ping; Zhang Chunlin

2012-01-01

The registered error between PET and CT imaging system was confirmed by a water model simulating clinical cases. A barrel of 6750 mL was filled with 59.2 MBq [ 18 F]-FDG and scanned after 80 min by 2 dimension model PET/CT. The CT images were used to attenuate the PET images. The CT/PET images were obtained by image morphological processing analyses without barrel wall. The relationship of the water image centroids of CT and PET images was established by linear regression analysis, and the registered error between PET and CT image could be computed one slice by one slice. The alignment program was done 4 times following the protocol given by GE Healthcare. Compared with centroids of water CT images, centroids of PET images were shifted to X-axis (0.011slice+0.63) mm, to Y-axis (0.022×slice+1.35) mm. To match CT images, PET images should be translated along X-axis (-2.69±0.15) mm, Y-axis (0.43±0.11) mm, Z-axis (0.86±0.23) mm, and X-axis be rotated by (0.06±0.07)°, Y-axis by (-0.01±0.08)°, and Z-axis by (0.11±0.07)°. So, the systematic registered error was not affected by load and its distribution. By finding the registered error between PET and CT images for coordinate rotation random error, the water model could confirm the registered results of PET-CT system corrected by Alignment parameters. (authors)

Drones, quasi-spin or iso-spin. A comparison of many-body techniques for general spin

International Nuclear Information System (INIS)

McKenzie, B.J.; Stedman, G.E.

1976-01-01

For an effective-spin system with 2S + 1 levels there are a number of possible mappings of spin onto pseudo-fermion operators. The relative merits of three of these methods are investigated by calculating to second order the dispersion relation for coupled spin-phonon modes in crystals containing S = 1 effective spin impurities. It is found that the drone formalism quickly becomes intractable at higher spin values, as does the related quasi-spin formalism developed in contrast with the iso-spin (or Abrinkosov projection) formalism. (author)

Spin-current emission governed by nonlinear spin dynamics.

Science.gov (United States)

Tashiro, Takaharu; Matsuura, Saki; Nomura, Akiyo; Watanabe, Shun; Kang, Keehoon; Sirringhaus, Henning; Ando, Kazuya

2015-10-16

Coupling between conduction electrons and localized magnetization is responsible for a variety of phenomena in spintronic devices. This coupling enables to generate spin currents from dynamical magnetization. Due to the nonlinearity of magnetization dynamics, the spin-current emission through the dynamical spin-exchange coupling offers a route for nonlinear generation of spin currents. Here, we demonstrate spin-current emission governed by nonlinear magnetization dynamics in a metal/magnetic insulator bilayer. The spin-current emission from the magnetic insulator is probed by the inverse spin Hall effect, which demonstrates nontrivial temperature and excitation power dependences of the voltage generation. The experimental results reveal that nonlinear magnetization dynamics and enhanced spin-current emission due to magnon scatterings are triggered by decreasing temperature. This result illustrates the crucial role of the nonlinear magnon interactions in the spin-current emission driven by dynamical magnetization, or nonequilibrium magnons, from magnetic insulators.

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.

Spin nematics next to spin singlets

Science.gov (United States)

Yokoyama, Yuto; Hotta, Chisa

2018-05-01

We provide a route to generate nematic order in a spin-1/2 system. Unlike the well-known magnon-binding mechanism, our spin nematics requires neither the frustration effect nor spin polarization in a high field or in the vicinity of a ferromagnet, but instead appears next to the spin singlet phase. We start from a state consisting of a quantum spin-1/2 singlet dimer placed on each site of a triangular lattice, and show that interdimer ring exchange interactions efficiently dope the SU(2) triplets that itinerate and interact, easily driving a stable singlet state to either Bose-Einstein condensates or a triplet crystal, some hosting a spin nematic order. A variety of roles the ring exchange serves includes the generation of a bilinear-biquadratic interaction between nearby triplets, which is responsible for the emergent nematic order separated from the singlet phase by a first-order transition.

Effect of orbital hybridization on spin-polarized tunneling across Co/C60 interfaces

NARCIS (Netherlands)

Wang, Kai; Strambini, Elia; Sanderink, Johannes G.M.; Bolhuis, Thijs; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

2016-01-01

The interaction between ferromagnetic surfaces and organic semiconductors leads to the formation of hybrid interfacial states. As a consequence, the local magnetic moment is altered, a hybrid interfacial density of states (DOS) is formed, and spin-dependent shifts of energy levels occur. Here, we

NMR magnetization exchange dynamics for three spin-1/2 systems

International Nuclear Information System (INIS)

Demco, D.E.; Filip, X.; Filip, C.

1997-01-01

The magnetization exchange dynamics in one-dimensional NMR exchange experiments performed with static samples is analyzed for the relevant case of three spin systems. The magnetization decays recorded in the experiments performed with different chemical shift filters for the short mixing times are derived analytically. In this regime the decay rates depend on the dipolar coupling between the spins belonging to different functional groups. The predictions of the theoretical model are compared with the magnetization exchange data obtained for cross-linked poly(styrene-co-butadiene) samples. The residual dipolar coupling between the functional CH- and CH2-groups of butadiene are measured from the magnetization exchange experiments in the short mixing time regime. (authors)

GPU accelerated manifold correction method for spinning compact binaries

Science.gov (United States)

Ran, Chong-xi; Liu, Song; Zhong, Shuang-ying

2018-04-01

The graphics processing unit (GPU) acceleration of the manifold correction algorithm based on the compute unified device architecture (CUDA) technology is designed to simulate the dynamic evolution of the Post-Newtonian (PN) Hamiltonian formulation of spinning compact binaries. The feasibility and the efficiency of parallel computation on GPU have been confirmed by various numerical experiments. The numerical comparisons show that the accuracy on GPU execution of manifold corrections method has a good agreement with the execution of codes on merely central processing unit (CPU-based) method. The acceleration ability when the codes are implemented on GPU can increase enormously through the use of shared memory and register optimization techniques without additional hardware costs, implying that the speedup is nearly 13 times as compared with the codes executed on CPU for phase space scan (including 314 × 314 orbits). In addition, GPU-accelerated manifold correction method is used to numerically study how dynamics are affected by the spin-induced quadrupole-monopole interaction for black hole binary system.

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.)

Resonant optical tunneling-induced enhancement of the photonic spin Hall effect

Science.gov (United States)

Jiang, Xing; Wang, Qingkai; Guo, Jun; Zhang, Jin; Chen, Shuqing; Dai, Xiaoyu; Xiang, Yuanjiang

2018-04-01

Due to the quantum analogy with optics, the resonant optical tunneling effect (ROTE) has been proposed to investigate both the fundamental physics and the practical applications of optical switches and liquid refractive index sensors. In this paper, the ROTE is used to enhance the spin Hall effect (SHE) of transmitted light. It is demonstrated that sandwiching a layer of a high-refractive-index medium (boron nitride crystal) between two low-refractive-index layers (silica) can effectively enhance the photonic SHE due to the increased refractive index gradient and an enhanced evanescent field near the interface between silica and boron nitride. A maximum transverse shift of the horizontal polarization state in the ROTE structure of about 22.25 µm has been obtained, which is at least three orders of magnitude greater than the transverse shift in the frustrated total internal reflection structure. Moreover, the SHE can be manipulated by controlling the component materials and the thickness of the ROTE structure. These findings open the possibility for future applications of photonic SHE in precision metrology and spin-based photonics.

Spin current through quantum-dot spin valves

International Nuclear Information System (INIS)

Wang, J; Xing, D Y

2006-01-01

We report a theoretical study of the influence of the Coulomb interaction on the equilibrium spin current in a quantum-dot spin valve, in which the quantum dot described by the Anderson impurity model is coupled to two ferromagnetic leads with noncollinear magnetizations. In the Kondo regime, electrons transmit through the quantum dot via higher-order virtual processes, in which the spin of either lead electrons or a localized electron on the quantum dot may reverse. It is found that the magnitude of the spin current decreases with increasing Coulomb interactions due to spin flip effects on the dot. However, the spatial direction of the spin current remains unchanged; it is determined only by the exchange coupling between two noncollinear magnetizations

Compound nucleus effects in spin-spin cross sections

International Nuclear Information System (INIS)

Thompson, W.J.

1976-01-01

By comparison with recent data, it is shown that spin-spin cross sections for low-energy neutrons may be dominated by a simple compound-elastic level-density effect, independent of spin-spin terms in the nucleon-nucleus optical-model potential. (Auth.)

Wives' Shift Work Schedules and Husbands' and Wives' Well-Being in Dual-Earner Couples with Children: A within-Couple Analysis

Science.gov (United States)

Chait Barnett, Rosalind; Gareis, Karen C.; Brennan, Robert T.

2008-01-01

In a sample of 55 dual-earner families with children aged 8 to 14 in which the mothers are registered nurses regularly working either day shifts (typically 7:00 a.m. to 3:00 p.m.) or evening shifts (typically 3:00 p.m. to 11:00 p.m.), we estimated the within-couple relationship between the wife's work variables (i.e., work shift, work hours, and…

Cavity Exciton-Polariton mediated, Single-Shot Quantum Non-Demolition measurement of a Quantum Dot Electron Spin

Science.gov (United States)

Puri, Shruti; McMahon, Peter; Yamamoto, Yoshihisa

2014-03-01

The quantum non-demolition (QND) measurement of a single electron spin is of great importance in measurement-based quantum computing schemes. The current single-shot readout demonstrations exhibit substantial spin-flip backaction. We propose a QND readout scheme for quantum dot (QD) electron spins in Faraday geometry, which differs from previous proposals and implementations in that it relies on a novel physical mechanism: the spin-dependent Coulomb exchange interaction between a QD spin and optically-excited quantum well (QW) microcavity exciton-polaritons. The Coulomb exchange interaction causes a spin-dependent shift in the resonance energy of the polarized polaritons, thus causing the phase and intensity response of left circularly polarized light to be different to that of the right circularly polarized light. As a result the QD electron's spin can be inferred from the response to a linearly polarized probe. We show that by a careful design of the system, any spin-flip backaction can be eliminated and a QND measurement of the QD electron spin can be performed within a few 10's of nanoseconds with fidelity 99:95%. This improves upon current optical QD spin readout techniques across multiple metrics, including fidelity, speed and scalability. National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.

Resonantly enhanced spin-lattice relaxation of Mn2 + ions in diluted magnetic (Zn,Mn)Se/(Zn,Be)Se quantum wells

Science.gov (United States)

Debus, J.; Ivanov, V. Yu.; Ryabchenko, S. M.; Yakovlev, D. R.; Maksimov, A. A.; Semenov, Yu. G.; Braukmann, D.; Rautert, J.; Löw, U.; Godlewski, M.; Waag, A.; Bayer, M.

2016-05-01

The dynamics of spin-lattice relaxation in the magnetic Mn2 + ion system of (Zn,Mn)Se/(Zn,Be)Se quantum-well structures are studied using optical methods. Pronounced cusps are found in the giant Zeeman shift of the quantum-well exciton photoluminescence at specific magnetic fields below 10 T, when the Mn spin system is heated by photogenerated carriers. The spin-lattice relaxation time of the Mn ions is resonantly accelerated at the cusp magnetic fields. Our theoretical analysis demonstrates that a cusp occurs at a spin-level mixing of single Mn2 + ions and a quick-relaxing cluster of nearest-neighbor Mn ions, which can be described as intrinsic cross-relaxation resonance within the Mn spin system.

Coherence and spin effects in quantum dots

International Nuclear Information System (INIS)

Katsumoto, S

2007-01-01

This review focuses on experiments on coherent transport through quantum dot systems. The most important quantity obtained in coherent transport is the phase shift through the dots, which gives complementary information to the scattering amplitude (i.e. the conductance). However, two-terminal devices have a particular difficulty, called 'phase rigidity', in obtaining the phase shift. There are two representative ways to avoid this problem: one is to adopt a multi-terminal configuration and another is to use resonance in the interferometer. This review mainly reviews the latter approaches. Such resonance in the whole interferometer often joins with local resonance inside the interferometer and appears as the Fano effect, which is a powerful tool for investigating the phase shift problem with the aid of theories. In addition to such resonances of single-electron states, electron spin causes a kind of many-body resonance, that is, the Kondo effect. Combination of these resonances is the Fano-Kondo effect. Experiments on the Fano-Kondo effect, which unveil the nature of the Kondo resonance, are also reviewed. (topical review)

Spin-curvature interaction from curved Dirac equation: Application to single-wall carbon nanotubes

Science.gov (United States)

Zhang, Kai; Zhang, Erhu; Chen, Huawei; Zhang, Shengli

2017-06-01

The spin-curvature interaction (SCI) and its effects are investigated based on curved Dirac equation. Through the low-energy approximation of curved Dirac equation, the Hamiltonian of SCI is obtained and depends on the geometry and spinor structure of manifold. We find that the curvature can be considered as field strength and couples with spin through Zeeman-like term. Then, we use dimension reduction to derive the local Hamiltonian of SCI for cylinder surface, which implies that the effective Hamiltonian of single-wall carbon nanotubes results from the geometry and spinor structure of lattice and includes two types of interactions: one does not break any symmetries of the lattice and only shifts the Dirac points for all nanotubes, while the other one does and opens the gaps except for armchair nanotubes. At last, analytical expressions of the band gaps and the shifts of their positions induced by curvature are given for metallic nanotubes. These results agree well with experiments and can be verified experimentally.

Optical spin generation/detection and spin transport lifetimes

International Nuclear Information System (INIS)

Miah, M. Idrish

2011-01-01

We generate electron spins in semiconductors by optical pumping. The detection of them is also performed by optical technique using time-resolved pump-probe photoluminescence polarization measurements in the presence of an external magnetic field perpendicular to the generated spin. The spin polarization in dependences of the pulse length, pump-probe delay and external magnetic field is studied. From the dependence of spin-polarization on the delay of the probe, the electronic spin transport lifetimes and the spin relaxation frequencies as a function of the strength of the magnetic field are estimated. The results are discussed based on hyperfine effects for interacting electrons.

Optical spin generation/detection and spin transport lifetimes

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2011-02-25

We generate electron spins in semiconductors by optical pumping. The detection of them is also performed by optical technique using time-resolved pump-probe photoluminescence polarization measurements in the presence of an external magnetic field perpendicular to the generated spin. The spin polarization in dependences of the pulse length, pump-probe delay and external magnetic field is studied. From the dependence of spin-polarization on the delay of the probe, the electronic spin transport lifetimes and the spin relaxation frequencies as a function of the strength of the magnetic field are estimated. The results are discussed based on hyperfine effects for interacting electrons.

Factors contributing to registered nurse medication administration error: a narrative review.

Science.gov (United States)

Parry, Angela M; Barriball, K Louise; While, Alison E

2015-01-01

To explore the factors contributing to Registered Nurse medication administration error behaviour. A narrative review. Electronic databases (Cochrane, CINAHL, MEDLINE, BNI, EmBase, and PsycINFO) were searched from 1 January 1999 to 31 December 2012 in the English language. 1127 papers were identified and 26 papers were included in the review. Data were extracted by one reviewer and checked by a second reviewer. A thematic analysis and narrative synthesis of the factors contributing to Registered Nurses' medication administration behaviour. Bandura's (1986) theory of reciprocal determinism was used as an organising framework. This theory proposes that there is a reciprocal interplay between the environment, the person and their behaviour. Medication administration error is an outcome of RN behaviour. The 26 papers reported studies conducted in 4 continents across 11 countries predominantly in North America and Europe, with one multi-national study incorporating 27 countries. Within both the environment and person domain of the reciprocal determinism framework, a number of factors emerged as influencing Registered Nurse medication administration error behaviour. Within the environment domain, two key themes of clinical workload and work setting emerged, and within the person domain the Registered Nurses' characteristics and their lived experience of work emerged as themes. Overall, greater attention has been given to the contribution of the environment domain rather than the person domain as contributing to error, with the literature viewing an error as an event rather than the outcome of behaviour. The interplay between factors that influence behaviour were poorly accounted for within the selected studies. It is proposed that a shift away from error as an event to a focus on the relationships between the person, the environment and Registered Nurse medication administration behaviour is needed to better understand medication administration error. Copyright © 2014

Negative optical spin torque wrench of a non-diffracting non-paraxial fractional Bessel vortex beam

Science.gov (United States)

Mitri, F. G.

2016-10-01

An absorptive Rayleigh dielectric sphere in a non-diffracting non-paraxial fractional Bessel vortex beam experiences a spin torque. The axial and transverse radiation spin torque components are evaluated in the dipole approximation using the radiative correction of the electric field. Particular emphasis is given on the polarization as well as changing the topological charge α and the half-cone angle of the beam. When α is zero, the axial spin torque component vanishes. However, when α becomes a real positive number, the vortex beam induces left-handed (negative) axial spin torque as the sphere shifts off-axially from the center of the beam. The results show that a non-diffracting non-paraxial fractional Bessel vortex beam is capable of inducing a spin reversal of an absorptive Rayleigh sphere placed arbitrarily in its path. Potential applications are yet to be explored in particle manipulation, rotation in optical tweezers, optical tractor beams, and the design of optically-engineered metamaterials to name a few areas.

Magnon and phonon dispersion, lifetime, and thermal conductivity of iron from spin-lattice dynamics simulations

Science.gov (United States)

Wu, Xufei; Liu, Zeyu; Luo, Tengfei

2018-02-01

In recent years, the fundamental physics of spin-lattice (e.g., magnon-phonon) interaction has attracted significant experimental and theoretical interests given its potential paradigm-shifting impacts in areas like spin-thermoelectrics, spin-caloritronics, and spintronics. Modelling studies of the transport of magnons and phonons in magnetic crystals are very rare. In this paper, we use spin-lattice dynamics (SLD) simulations to model ferromagnetic crystalline iron, where the spin and lattice systems are coupled through the atomic position-dependent exchange function, and thus the interaction between magnons and phonons is naturally considered. We then present a method combining SLD simulations with spectral energy analysis to calculate the magnon and phonon harmonic (e.g., dispersion, specific heat, and group velocity) and anharmonic (e.g., scattering rate) properties, based on which their thermal conductivity values are calculated. This work represents an example of using SLD simulations to understand the transport properties involving coupled magnon and phonon dynamics.

Shift work and hypertension: Prevalence and analysis of disease pathways in a German car manufacturing company.

Science.gov (United States)

Ohlander, Johan; Keskin, Mekail-Cem; Stork, Joachim; Radon, Katja

2015-05-01

Hypertension and cardiovascular disease (CVD) may share a similar pathophysiology. Despite shift workers' CVD excess risk, studies on shift work and hypertension are inconclusive. Blood pressure and shift status for 25,343 autoworkers were obtained from medical check-ups and company registers. Cross-sectional associations modeling the total effect from shift work (day shifts, shift work without nights, rotating shift work with nights, and night shifts) on hypertension were assessed. By sequential adjustments, the influence of behavioral, psychosocial, and physiological factors on the total effect was examined, with subsequent mediation and moderation analyses. Adjusted for confounders, shift work without nights (vs. day shifts) was significantly associated with hypertension (OR 1.15, 95%CI 1.02-1.30). The total effect was mediated by BMI, physical inactivity, and sleep disorders. No moderation of the total effect by behaviors was found. The association between shift work and hypertension seems mainly attributable to behavioral mechanisms. © 2015 Wiley Periodicals, Inc.

Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

International Nuclear Information System (INIS)

Atitoaie, Alexandru; Tanasa, Radu; Enachescu, Cristian

2012-01-01

Spin crossover compounds are photo-magnetic bistable molecular magnets with two states in thermodynamic competition: the diamagnetic low-spin state and paramagnetic high-spin state. The thermal transition between the two states is often accompanied by a wide hysteresis, premise for possible application of these materials as recording media. In this paper we study the influence of the system's size on the thermal hysteresis loops using Monte Carlo simulations based on an Arrhenius dynamics applied for an Ising like model with long- and short-range interactions. We show that using appropriate boundary conditions it is possible to reproduce both the drop of hysteresis width with decreasing particle size, the hysteresis shift towards lower temperatures and the incomplete transition, as in the available experimental data. The case of larger systems composed by several sublattices is equally treated reproducing the shrinkage of the hysteresis loop's width experimentally observed. - Highlights: ► A study concerning size effects in spin crossover nanoparticles hysteresis is presented. ► An Ising like model with short- and long-range interactions and Arrhenius dynamics is employed. ► In open boundary system the hysteresis width decreases with particle size. ► With appropriate environment, hysteresis loop is shifted towards lower temperature and transition is incomplete.

Dynamic-angle spinning and double rotation of quadrupolar nuclei

International Nuclear Information System (INIS)

Mueller, K.T.; California Univ., Berkeley, CA

1991-07-01

Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-1/2 nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids

Dynamic-angle spinning and double rotation of quadrupolar nuclei

Energy Technology Data Exchange (ETDEWEB)

Mueller, K.T. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Chemistry)

1991-07-01

Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-{1/2} nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids.

Angular dependence of spin-orbit spin-transfer torques

KAUST Repository

Lee, Ki-Seung

2015-04-06

In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

Angular dependence of spin-orbit spin-transfer torques

KAUST Repository

Lee, Ki-Seung; Go, Dongwook; Manchon, Aurelien; Haney, Paul M.; Stiles, M. D.; Lee, Hyun-Woo; Lee, Kyung-Jin

2015-01-01

In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

Numerical simulation of a quantum controlled-not gate implemented on four-spin molecules at room temperature

CERN Document Server

López, G V; Berman, G P; Doolen, G D; Tsifrinovich, V I

2003-01-01

We study numerically the non-resonant effects on four-spin molecules at room temperature with the implemented quantum controlled-not gate and using the 2 pi k method. The four nuclear spins in each molecule represent a four-qubit register. The qubits interact with each other through Ising-type interaction which is characterized by the coupling constant J sub a sub , sub b. We study the errors on the reduced density matrix as a function of the Rabi frequency, OMEGA, using the 2 pi k method and when all the coupling constants are equal or when one of them is different from the others.

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.

Microscopic studies of nonlocal spin dynamics and spin transport (invited)

Energy Technology Data Exchange (ETDEWEB)

Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris, E-mail: hammel@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)

2015-05-07

Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

Microscopic studies of nonlocal spin dynamics and spin transport (invited)

Science.gov (United States)

Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

2015-05-01

Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

Microscopic studies of nonlocal spin dynamics and spin transport (invited)

International Nuclear Information System (INIS)

Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

2015-01-01

Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems

Noise in tunneling spin current across coupled quantum spin chains

Science.gov (United States)

Aftergood, Joshua; Takei, So

2018-01-01

We theoretically study the spin current and its dc noise generated between two spin-1 /2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and we compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a concomitant divergence in the spin Fano factor, defined as the spin current noise-to-signal ratio. This divergence is shown to have an exact analogy to the physics of electron scattering between fractional quantum Hall edge states and not to arise in the magnon scenario. We also reveal a suppression in the spin current noise that exclusively arises in the spin chain scenario due to the fermion nature of the spin-1/2 operators. We discuss how the spin Fano factor may be extracted experimentally via the inverse spin Hall effect used extensively in spintronics.

When measured spin polarization is not spin polarization

International Nuclear Information System (INIS)

Dowben, P A; Wu Ning; Binek, Christian

2011-01-01

Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO 2 and Cr 2 O 3 illustrate some of the complications which hinders comparisons of spin polarization values. (viewpoint)

Magnetic Nanostructures Spin Dynamics and Spin Transport

CERN Document Server

Farle, Michael

2013-01-01

Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

pH control and rapid mixing in spinning NMR samples

Science.gov (United States)

Yesinowski, James P.; Sunberg, Richard J.; Benedict, James J.

An apparatus is described which permits the acquisition of NMR spectra from spinning 20-mm sample tubes while: (1) constantly monitoring the pH; (2) adding reagents to maintain constant pH (pH-statting); (3) efficiently mixing the added reagent. The apparatus was built to study the spontaneous precipitation of calcium phosphates from supersaturated solutions using 31P NMR. Other applications include the rapid determination of NMR titration curves, and the minimization of temperature gradients in large sample tubes. The apparatus was used to measure the 31P chemical shift titration of dilute phosphoric acid, which yielded accurate shifts for the three species of protonated orthophosphate ion. The bulk magnetic susceptibility of 85% H 3PO 4 relative to a dilute aqueous sample was also measured, and is shown to contribute significantly to chemical shift measurements.

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

Spin Relaxation and Manipulation in Spin-orbit Qubits

Science.gov (United States)

Borhani, Massoud; Hu, Xuedong

2012-02-01

We derive a generalized form of the Electric Dipole Spin Resonance (EDSR) Hamiltonian in the presence of the spin-orbit interaction for single spins in an elliptic quantum dot (QD) subject to an arbitrary (in both direction and magnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi frequency as a function of the magnetic field for sufficiently large Zeeman energies, and present a microscopic expression for the anisotropic electron g-tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a double quantum dot (DQD). Finally, we calculate two-electron-spin relaxation rates due to phonon emission, for both in-plane and perpendicular magnetic fields. Our results have immediate applications to current EDSR experiments on nanowire QDs, g-factor optimization of confined carriers, and spin decay measurements in DQD spin-orbit qubits.

Nonlinear spin current generation in noncentrosymmetric spin-orbit coupled systems

Science.gov (United States)

Hamamoto, Keita; Ezawa, Motohiko; Kim, Kun Woo; Morimoto, Takahiro; Nagaosa, Naoto

2017-06-01

Spin current plays a central role in spintronics. In particular, finding more efficient ways to generate spin current has been an important issue and has been studied actively. For example, representative methods of spin-current generation include spin-polarized current injections from ferromagnetic metals, the spin Hall effect, and the spin battery. Here, we theoretically propose a mechanism of spin-current generation based on nonlinear phenomena. By using Boltzmann transport theory, we show that a simple application of the electric field E induces spin current proportional to E2 in noncentrosymmetric spin-orbit coupled systems. We demonstrate that the nonlinear spin current of the proposed mechanism is supported in the surface state of three-dimensional topological insulators and two-dimensional semiconductors with the Rashba and/or Dresselhaus interaction. In the latter case, the angular dependence of the nonlinear spin current can be manipulated by the direction of the electric field and by the ratio of the Rashba and Dresselhaus interactions. We find that the magnitude of the spin current largely exceeds those in the previous methods for a reasonable magnitude of the electric field. Furthermore, we show that application of ac electric fields (e.g., terahertz light) leads to the rectifying effect of the spin current, where dc spin current is generated. These findings will pave a route to manipulate the spin current in noncentrosymmetric crystals.

Shift work and overall and cause-specific mortality in the Danish nurse cohort

DEFF Research Database (Denmark)

Jørgensen, Jeanette Therming; Karlsen, Sashia; Stayner, Leslie T.

2017-01-01

Objectives: Evidence of an effect of shift work on all-cause and cause-specific mortality is inconsistent. This study aims to examine whether shift work is associated with increased all-cause and cause-specific mortality.  Methods: We linked 28 731 female nurses (age ≥44 years), recruited in 1993...... or 1999 from the Danish nurse cohort where they reported information on shift work (night, evening, rotating, or day), to the Danish Register of Causes of Death to identify deaths up to 2013. We used Cox regression models with age as the underlying scale to examine the associations between night, evening......, and rotating shift work (compared to day shift work) and all-cause and cause-specific mortality in models adjusted for potentially confounding variables.  Results: Of 18 015 nurses included in this study, 1616 died during the study time period from the following causes: cardiovascular disease (N=217), cancer...

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.

Nuclear spin-spin coupling constants of linear carbon chains terminated by coronene molecules: a first principles study

International Nuclear Information System (INIS)

Oliveira, Joao Paulo Cavalcante; Mota, F. de Brito; Rivelino, Roberto

2011-01-01

Full text. Carbon nano wires made of long linear atomic chains have attracted considerable interest due to their potential applications in nano electronics. We report a density-functional-theory study of the nuclear spin-spin coupling constants for nano assemblies made of two coronene molecules bridged by carbon linear chains, considering distinct sizes and spin multiplicities. Also, we examine the effects of two terminal conformations (syn and anti) of the terminal anchor pieces on the magnetic properties of the carbon chains via 13 C NMR calculations. Our results reveal that simplified chemical models such as those based on cumulenes or polyynes are not appropriate to describe the linear chains with sp 2 terminations. For these types of atomic chains, the electronic ground state of the even-numbered chains can be singlet or triplet, whereas the ground state of the odd-numbered chains can be doublet or quartet. We discuss how the 13 C NMR chemical shift absorption is affected by increasing the size and changing the parity of the linear carbon chains. We have found that the J coupling constants between the carbon atoms in the linear chains present a well-defined pattern, in good accordance with our electronic structure calculations. For example, in the -C 4 - units we obtain couplings of 43.8, 114.5, 84.6, 114.5, and 43.8 Hz from one end to the other

Debug register rootkits : A study of malicious use of the IA-32 debug registers

OpenAIRE

Persson, Emil; Mattsson, Joel

2012-01-01

The debug register rootkit is a special type of rootkit that has existed for over a decade, and is told to be undetectable by any scanning tools. It exploits the debug registers in Intel’s IA-32 processor architecture. This paper investigates the debug register rootkit to find out why it is considered a threat, and which malware removal tools have implemented detection algorithms against this threat. By implementing and running a debug register rootkit against the most popular Linux tools, ne...

Electron spin and nuclear spin manipulation in semiconductor nanosystems

International Nuclear Information System (INIS)

Hirayama, Yoshiro; Yusa, Go; Sasaki, Satoshi

2006-01-01

Manipulations of electron spin and nuclear spin have been studied in AlGaAs/GaAs semiconductor nanosystems. Non-local manipulation of electron spins has been realized by using the correlation effect between localized and mobile electron spins in a quantum dot- quantum wire coupled system. Interaction between electron and nuclear spins was exploited to achieve a coherent control of nuclear spins in a semiconductor point contact device. Using this device, we have demonstrated a fully coherent manipulation of any two states among the four spin levels of Ga and As nuclei. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bulk electron spin polarization generated by the spin Hall current

OpenAIRE

Korenev, V. L.

2005-01-01

It is shown that the spin Hall current generates a non-equilibrium spin polarization in the interior of crystals with reduced symmetry in a way that is drastically different from the previously well-known equilibrium polarization during the spin relaxation process. The steady state spin polarization value does not depend on the strength of spin-orbit interaction offering possibility to generate relatively high spin polarization even in the case of weak spin-orbit coupling.

Bulk electron spin polarization generated by the spin Hall current

Science.gov (United States)

Korenev, V. L.

2006-07-01

It is shown that the spin Hall current generates a nonequilibrium spin polarization in the interior of crystals with reduced symmetry in a way that is drastically different from the previously well-known “equilibrium” polarization during the spin relaxation process. The steady state spin polarization value does not depend on the strength of spin-orbit interaction offering possibility to generate relatively high spin polarization even in the case of weak spin-orbit coupling.

Determination of the Pt spin diffusion length by spin-pumping and spin Hall effect

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei; Pearson, John E.; Hoffmann, Axel [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Vlaminck, Vincent [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Colegio de Ciencias e Ingenería, Universidad San Fransciso de Quito, Quito (Ecuador); Divan, Ralu [Center for Nanoscale Materials, Argonne National Laboratory, Illinois 60439 (United States); Bader, Samuel D. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Illinois 60439 (United States)

2013-12-09

The spin diffusion length of Pt at room temperature and at 8 K is experimentally determined via spin pumping and spin Hall effect in permalloy/Pt bilayers. Voltages generated during excitation of ferromagnetic resonance from the inverse spin Hall effect and anisotropic magnetoresistance effect were investigated with a broadband approach. Varying the Pt layer thickness gives rise to an evolution of the voltage line shape due to the superposition of the above two effects. By studying the ratio of the two voltage components with the Pt layer thickness, the spin diffusion length of Pt can be directly extracted. We obtain a spin diffusion length of ∼1.2 nm at room temperature and ∼1.6 nm at 8 K.

The Danish Adoption Register.

Science.gov (United States)

Petersen, Liselotte; Sørensen, Thorkild I A

2011-07-01

The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia. The register encompass information on all 14,425 non-familial adoptions of Danish children legally granted in Denmark 1924-1947. It includes name and date of birth of each adoptee and his or her biological and adoptive parents, date of transfer to adoptive parents and date of formal adoption. The linkage to biological and adoptive parents is close to complete, even biological fathers are registered for 91.4% of the adoptees. Adoption registers are a unique source allowing disentangling of genetic and familial environmental influences on traits, risk of diseases, and mortality.

Fragmentation of spin-dipole strength in 90Zr and 208Pb

International Nuclear Information System (INIS)

Marketin, T.; Litvinova, E.; Vretenar, D.; Ring, P.

2012-01-01

An extension of time-dependent covariant density functional theory that includes particle-vibration coupling is applied to the charge-exchange channel. Spin-dipole excitation spectra are calculated an compared to available data for 90 Zr and 208 Pb. A significant fragmentation is found for all three angular-momentum components of the spin-dipole strength as a result of particle-vibration coupling, as well as a shift of a portion of the strength to higher energy. A high-energy tail is formed in the strength distribution that linearly decreases with energy. Using a model-independent sum rule, the corresponding neutron skin thickness is estimated and shown to be consistent with values obtained at the mean-field level.

Fluid dynamics of giant resonances on high spin states

International Nuclear Information System (INIS)

Di Nardo, M.; Di Toro, M.; Giansiracusa, G.; Lombardo, U.; Russo, G.

1983-01-01

We describe giant resonances built on high spin states along the yrast line as scaling solutions of a linearized Vlasov equation in a rotating frame obtained from a TDHF theory in phase space. For oblate cranked solutions we get a shift and a splitting of the isoscalar giant resonances in terms of the angular velocity. Results are shown for 40 Ca and 168 Er. The relative CM strengths are also calculated. (orig.)

Control of propagation characteristics of spin wave pulses via elastic and thermal effects

Energy Technology Data Exchange (ETDEWEB)

Gómez-Arista, Ivan [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Kolokoltsev, O., E-mail: oleg.kolokoltsev@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Acevedo, A.; Qureshi, N. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Ordóñez-Romero, César L. [Instituto de Física, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico)

2017-05-01

A study of the magnetoelastic (ME) and thermal effects governing the phase (φ) and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides is presented. The ME effects were studied in a flexural configuration, under punctual mechanical force (F). Thermally induced ME and demagnetization phenomena were controlled by optically injected thermal power P{sub th}. It was determined that in an unclamped Ga:YIG waveguide, the force F that induces the phase shift Δφ=π, decreases by a quadratic law in the range from 1 mN to nN, and the P{sub th} at which Δφ=π decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. For nano-volume waveguides the ME control energy (E{sub me}) can be of order of aJ, and the thermal control energy (ΔE{sub th}) can be as small as 50 fJ. The response time of these effects lies in the ns time scale. Both the mechanical and the thermo-magnetic forces provide an effective control of MSSW pulse amplitude, in addition to its phase shift. The thermo-magnetic effect allows one to realize variable delays of a MSSW pulse. - Highlights: • The Magneto-elastic (ME) and optically induced thermal effects governing the phase and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides are presented. • A mechanical force that causes phase shift Δφ=π for spin waves in the waveguides decreases by a quadratic law in the range from 1 mN to nN, and the optical power that induces the phase shift Δφ=π, decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. • The response time of these effects can lie in the ns time scale.

Employer-provided support services and job dissatisfaction in Canadian registered nurses.

Science.gov (United States)

Wilkins, Kathryn; Shields, Margot

2012-10-01

Previous research indicates that nurses' job dissatisfaction relates to their work organization and environment; rarely has the contribution of employer provided support services been examined while controlling for the influence of other factors. The objective of this study was to examine job dissatisfaction among Canadian registered nurses in relation to employer-provided programs for child care and fitness or recreation. Data are from 2,993 respondents to the 2005 National Survey of the Work and Health of Nurses, weighted to represent Canada's 91,600 registered nurses in full-time, permanent positions who deliver direct care in hospitals or long-term care facilities. Multivariate modeling was used to examine job dissatisfaction in relation to employer-provided support programs, controlling for personal characteristics and variables reflecting work organization and the work environment. Employer-provided child care assistance programs were available to 16% of nurses, and fitness or recreation programs were available to 38%. An estimated 13% of nurses were dissatisfied with their jobs. Even when controlling for personal characteristics, overtime, shift work, shift length, weekly hours, overload, staffing inadequacy, autonomy, nurse-physician relations, and coworker respect, inverse associations with job dissatisfaction emerged for employer-supported child care (odds ratio = 0.49, 95% confidence interval = 0.27-0.88) and fitness programs (odds ratio = 0.65, 95% confidence interval = 0.42-0.99). This study provides new information suggesting that employer-provided support programs are protective against nurses' job dissatisfaction. This is a key finding in view of nursing shortages and the importance of job satisfaction to retention.

Danish registers on aspects of reproduction

DEFF Research Database (Denmark)

Blenstrup, Lene Tølbøll; Knudsen, Lisbeth B.

2011-01-01

Introduction: The establishing of three Danish population based registers, namely the Fertility Database, the Register of Legally Induced Abortions and the In Vitro Fertilisation register aimed at providing data for surveying of reproductive outcome. Content: The registers include information...... on births, abortions and assisted reproduction as well as selected characteristics of the women (and men) involved. Validity and Coverage: Both the validity and coverage of each register is considered of high quality. Conclusions: These registers provide, both individually and in combination, unique...

Design and performance of the Lamb-shift polarimeter

International Nuclear Information System (INIS)

Kremers, H.R.; Beijers, J.P.M.; Kalantar-Nayestanaki, N.

2005-01-01

A new compact low-energy polarimeter has been designed, developed and put into operation, based on the principle of Lamb-shift polarimetry. Here, we focus on ion-beam deceleration (14-35 kV to 500 V) and the polarimeter's magnetic field. The determination of the optimal setting of oven temperature and the DC gradient in the spin-filter will be presented and illustrated with some measurements. Further, performance of the polarized ion source will be shown by some typical measurements on proton and deuteron beams with the polarimeter

Muon spin relaxation measurements of spin-correlation decay in spin-glass AgMn

Energy Technology Data Exchange (ETDEWEB)

Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E. (Los Alamos National Lab., NM (USA)); MacLaughlin, D.E.; Gupta, L.C. (California Univ., Riverside (USA))

1984-01-01

The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin glass temperature in AgMn is found to obey an algebraic form given by (H)sup(..gamma..-1), with ..gamma.. = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as tsup(-..gamma..), in agreement with mean field theories of spin-glass dynamics which yield ..gamma..

Lagrangian-Hamiltonian formalism for the gravitational two-body problem with spin and parametrized post-Newtonian parameters γ and β

International Nuclear Information System (INIS)

Barker, B.M.; O'Connell, R.F.

1976-01-01

We generalize the Lagrangian and Hamiltonian of our previous work on the gravitational two-body problem with spin by including the parametrized-post-Newtonian parameters γ and β. By this procedure we are able to obtain the precession of the orbit as well as the precession of the spin. Equations of motion corresponding to an arbitrary-spin supplementary condition are also given. Finally we show how the masses of the binary pulsar PSR 1913 + 16 and its companion are related to the orbit and spin precessions. Combining this with a result derivable from the second-order Doppler effect and the gravitational red-shift, we obtain a relation constraining the values that γ and β can take

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 manipulation and relaxation in spin-orbit qubits

Science.gov (United States)

Borhani, Massoud; Hu, Xuedong

2012-03-01

We derive a generalized form of the electric dipole spin resonance (EDSR) Hamiltonian in the presence of the spin-orbit interaction for single spins in an elliptic quantum dot (QD) subject to an arbitrary (in both direction and magnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi frequency as a function of the magnetic field for sufficiently large Zeeman energies, and present a microscopic expression for the anisotropic electron g tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a double quantum dot (DQD), where coherent Rabi oscillations between the singlet and triplet states are induced by jittering the inter-dot distance at the resonance frequency. Finally, we calculate two-electron-spin relaxation rates due to phonon emission, for both in-plane and perpendicular magnetic fields. Our results have immediate applications to current EDSR experiments on nanowire QDs, g-factor optimization of confined carriers, and spin decay measurements in DQD spin-orbit qubits.

Spin transfer torque with spin diffusion in magnetic tunnel junctions

KAUST Repository

Manchon, Aurelien

2012-08-09

Spin transport in magnetic tunnel junctions in the presence of spin diffusion is considered theoretically. Combining ballistic tunneling across the barrier and diffusive transport in the electrodes, we solve the spin dynamics equation in the metallic layers. We show that spin diffusion mixes the transverse spin current components and dramatically modifies the bias dependence of the effective spin transfer torque. This leads to a significant linear bias dependence of the out-of-plane torque, as well as a nonconventional thickness dependence of both spin torque components.

Effect of Orbital Hybridization on Spin-Polarized Tunneling across Co/C60 Interfaces.

Science.gov (United States)

Wang, Kai; Strambini, Elia; Sanderink, Johnny G M; Bolhuis, Thijs; van der Wiel, Wilfred G; de Jong, Michel P

2016-10-26

The interaction between ferromagnetic surfaces and organic semiconductors leads to the formation of hybrid interfacial states. As a consequence, the local magnetic moment is altered, a hybrid interfacial density of states (DOS) is formed, and spin-dependent shifts of energy levels occur. Here, we show that this hybridization affects spin transport across the interface significantly. We report spin-dependent electronic transport measurements for tunnel junctions comprising C 60 molecular thin films grown on top of face-centered-cubic (fcc) epitaxial Co electrodes, an AlO x tunnel barrier, and an Al counter electrode. Since only one ferromagnetic electrode (Co) is present, spin-polarized transport is due to tunneling anisotropic magnetoresistance (TAMR). An in-plane TAMR ratio of approximately 0.7% has been measured at 5 K under application of a magnetic field of 800 mT. The magnetic switching behavior shows some remarkable features, which are attributed to the rotation of interfacial magnetic moments. This behavior can be ascribed to the magnetic coupling between the Co thin films and the newly formed Co/C 60 hybridized interfacial states. Using the Tedrow-Meservey technique, the tunnel spin polarization of the Co/C 60 interface was found to be 43%.

Shift work, long working hours, and later risk of dementia

DEFF Research Database (Denmark)

Nabe-Nielsen, Kirsten; Garde, Anne Helene; Ahmed, Kazi Ishtiak

2017-01-01

Objectives: The aim of this study was to investigate the effect of shift work and long working hours in midlife on the risk of dementia in old age. Methods: The present study comprised 4766 participants from the Copenhagen Male Study. We used information on shift work (collected in 1970......–1971 and 1985–1986), long working hours defined as >45 hours per week (collected in 1970–1971), socioeconomic status, sleep, stress, and cardiovascular risk factors. Information about dementia diagnoses was obtained from registers. Participants were followed until 2014 (mean length of follow-up was 17.8 years......). We employed Poisson regression for the survival analyses and estimated incidence rate ratios (IRR) and their 95% confidence intervals (CI). Results: We found no statistically significant association between shift work (IRR 0.86, 95% CI 0.70–1.05) or long working hours (IRR 0.97, 95% CI 0...

Results from EDDA at COSY: Spin Observables in Proton-Proton Elastic Scattering

International Nuclear Information System (INIS)

Rohdjess, Heiko

2003-01-01

Elastic proton-proton scattering as one of the fundamental hadronic reactions has been studied with the internal target experiment EDDA at the Cooler-Synchrotron COSY/Juelich. A precise measurement of differential cross section, analyzing power and three spin-correlation parameters over a large angular (θc.m. ≅ 35 deg. - 90 deg.) and energy (Tp ≅ 0.5 - 2.5 GeV) range has been carried out in the past years. By taking scattering data during the acceleration of the COSY beam, excitation functions were measured in small energy steps and consistent normalization with respect to luminosity and polarization. The experiment uses internal fiber targets and a polarized hydrogen atomic-beam target in conjunction with a double-layered, cylindrical scintillator hodoscope for particle detection. The results on differential cross sections and analyzing powers have been published and helped to improve phase shift solutions. Recently data taking with polarized beam and target has been completed. Preliminary results for the spin-correlation parameters A NN, ASS, and ASL are presented. The observable ASS has been measured the first time above 800 MeV and our results are in sharp contrast to phase-shift predictions at higher energies. Our analysis shows that some of the ambiguities in the direct reconstruction of scattering amplitudes which also show up as differences between available phase-shift solutions, will be reduced by these new measurements

Muon spin relaxation measurements of spin-correlation decay in spin-glass AgMn

International Nuclear Information System (INIS)

Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Gupta, L.C.

1984-01-01

The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin glass temperature in AgMn is found to obey an algebraic form given by (H)sup(γ-1), with γ = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as tsup(-γ), in agreement with mean field theories of spin-glass dynamics which yield γ < approx. 0.5. Near the glass temperature the agreement between the data and theory is not as good. (Auth.)

Spin-orbit mediated control of spin qubits

DEFF Research Database (Denmark)

Flindt, Christian; Sørensen, A.S; Flensberg, Karsten

2006-01-01

We propose to use the spin-orbit interaction as a means to control electron spins in quantum dots, enabling both single-qubit and two-qubit operations. Very fast single-qubit operations may be achieved by temporarily displacing the electrons. For two-qubit operations the coupling mechanism is bas...... on a combination of the spin-orbit coupling and the mutual long-ranged Coulomb interaction. Compared to existing schemes using the exchange coupling, the spin-orbit induced coupling is less sensitive to random electrical fluctuations in the electrodes defining the quantum dots....

Spinning particle approach to higher spin field theory

International Nuclear Information System (INIS)

Corradini, Olindo

2011-01-01

We shortly review on the connection between higher-spin gauge field theories and supersymmetric spinning particle models. In such approach the higher spin equations of motion are linked to the first-class constraint algebra associated with the quantization of particle models. Here we consider a class of spinning particle models characterized by local O(N)-extended supersymmetry since these models are known to provide an alternative approach to the geometric formulation of higher spin field theory. We describe the canonical quantization of the models in curved target space and discuss the obstructions that appear in presence of an arbitrarily curved background. We then point out the special role that conformally flat spaces appear to have in such models and present a derivation of the higher-spin curvatures for maximally symmetric spaces.

Shot noise of spin current and spin transfer torque

Science.gov (United States)

Yu, Yunjin; Zhan, Hongxin; Wan, Langhui; Wang, Bin; Wei, Yadong; Sun, Qingfeng; Wang, Jian

2013-04-01

We report the theoretical investigation of the shot noise of the spin current (Sσ) and the spin transfer torque (Sτ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear Sσ - V and Sτ - V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage Nτ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque Nτ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period Nτ(θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters.

How registered nurses, licensed practical nurses and resident aides spend time in nursing homes: An observational study.

Science.gov (United States)

McCloskey, Rose; Donovan, Cindy; Stewart, Connie; Donovan, Alicia

2015-09-01

Calls for improved conditions in nursing homes have pointed to the importance of optimizing the levels and skills of care providers. Understanding the work of care providers will help to determine if staff are being used to their full potential and if opportunities exist for improved efficiencies. To explore the activities of care providers in different nursing homes and to identify if variations exist within and across homes and shifts. A multi-centre cross-sectional observational work flow study was conducted in seven different nursing homes sites in one Canadian province. Data were collected by a research assistant who conducted 368 h of observation. The research assistant collected data by following an identical route in each site and recording observations on staff activities. Findings indicate staff activities vary across roles, sites and shifts. Licensed practical nurses (nursing assistants) have the greatest variation in their role while registered nurses have the least amount of variability. In some sites both registered nurses and licensed practical nurses perform activities that may be safely delegated to others. Care providers spend as much as 53.7% of their time engaged in non-value added activities. There may be opportunities for registered nurses and licensed practical nurses to delegate some of their activities to non-regulated workers. The time care providers spend in non-value activities suggest there may be opportunities to improve efficiencies within the nursing home setting. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spin precession and spin Hall effect in monolayer graphene/Pt nanostructures

Science.gov (United States)

Savero Torres, W.; Sierra, J. F.; Benítez, L. A.; Bonell, F.; Costache, M. V.; Valenzuela, S. O.

2017-12-01

Spin Hall effects have surged as promising phenomena for spin logics operations without ferromagnets. However, the magnitude of the detected electric signals at room temperature in metallic systems has been so far underwhelming. Here, we demonstrate a two-order of magnitude enhancement of the signal in monolayer graphene/Pt devices when compared to their fully metallic counterparts. The enhancement stems in part from efficient spin injection and the large spin resistance of graphene but we also observe 100% spin absorption in Pt and find an unusually large effective spin Hall angle of up to 0.15. The large spin-to-charge conversion allows us to characterise spin precession in graphene under the presence of a magnetic field. Furthermore, by developing an analytical model based on the 1D diffusive spin-transport, we demonstrate that the effective spin-relaxation time in graphene can be accurately determined using the (inverse) spin Hall effect as a means of detection. This is a necessary step to gather full understanding of the consequences of spin absorption in spin Hall devices, which is known to suppress effective spin lifetimes in both metallic and graphene systems.

Muon spin-relaxation measurements of spin-correlation decay in spin-glass AgMn

International Nuclear Information System (INIS)

Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Gupta, L.C.

1983-01-01

The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin-glass temperature in AgMn is found to obey an algebraic form given by (H)/sup nu-1/, with nu = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as t - /sup nu/, in agreement with mean field theories of spin-glass dynamics which yield nu less than or equal to 0.5. Near the glass temperature the agreement between the data and theory is not as good

The possibilities and limitations of neuronavigation method in the treatment of intracranial pathology, on the basis of anatomic registering markers and preoperative magnetic resonance imaging

International Nuclear Information System (INIS)

Lickendorf, M.

2007-01-01

Introduction: The evaluation of technical parameters of the system and the evaluation of the influence of changing intraoperative conditions on the accuracy of the indications of the neuronavigational system has the key meaning in the effectiveness on the work of a neurosurgeon. On the other hand the employment of neuronavigation during an operation on the brain allows to get an insight into the dynamics and directions of the shifts of individual brain structures in regard to themselves and hard integuments. Material and methods: In the experimental part of the work an analysis was done of the theoretical and actual accuracy of indications of the neuronavigational system obtained after the registering process in modal and clinical conditions. In the clinical part of the work, during the operations of 69 patients with the use of the neuronavigational system an analysis was done of the dynamics and the direction of shifts of the brain's surface and the boundaries of pathological focus in regard to the placement and volume of the pathological focus, volume of the peritumorous edema and the usage of the escape of the cerebrospinal fluid, as well as resulting from those shifts the divergence in the indications of the neuronavigational system. Results and conclusions: A smaller accuracy of the neuronavigational system in clinical than in modal conditions was proved. Anatomical registering markers cause the shifts of areas of greatest accuracy to the face area of patients, not including in its range the back sides of the head and there localized 65.4% of pathological focuses. In model and clinical conditions significant differences between computer error of the RMSE registering process and the marker localization error empirically defined were proved. In result of the analysis of the shifts of the cerebral cortex during the operation of tumors: Meta, Astr. II, Astr. III, GBM, vascular and intrachamberal it was proved that the peritumorous edema, the volume of the

Negative optical spin torque wrench of a non-diffracting non-paraxial fractional Bessel vortex beam

International Nuclear Information System (INIS)

Mitri, F.G.

2016-01-01

An absorptive Rayleigh dielectric sphere in a non-diffracting non-paraxial fractional Bessel vortex beam experiences a spin torque. The axial and transverse radiation spin torque components are evaluated in the dipole approximation using the radiative correction of the electric field. Particular emphasis is given on the polarization as well as changing the topological charge α and the half-cone angle of the beam. When α is zero, the axial spin torque component vanishes. However, when α becomes a real positive number, the vortex beam induces left-handed (negative) axial spin torque as the sphere shifts off-axially from the center of the beam. The results show that a non-diffracting non-paraxial fractional Bessel vortex beam is capable of inducing a spin reversal of an absorptive Rayleigh sphere placed arbitrarily in its path. Potential applications are yet to be explored in particle manipulation, rotation in optical tweezers, optical tractor beams, and the design of optically-engineered metamaterials to name a few areas. - Highlights: • Optical nondiffracting nonparaxial fractional Bessel vortex beam is considered. • Negative spin torque on an absorptive dielectric Rayleigh sphere is predicted numerically. • Negative spin torque occurs as the sphere departs from the center of the beam.

Blue shift of the plasma edge of a ferromagnetic semimetal

International Nuclear Information System (INIS)

Wachter, P.; Bommeli, F.; Degiorgi, L.; Burlet, P.; Bourdarot, F.

1998-01-01

Full text: In general rare earth pnictides are semimetals and antiferromagnets. Only some nitrides are quoted as ferri or ferromagnetic. However, it has been shown when prepared stoichiometrically and in single crystalline form the free carrier concentration is only in the percent per cation range, thus they are typical low carrier systems. Under these conditions the nitrides are all canted antiferromagnets and metamagnets, i.e. they show Abstract only. The full magnetic moment only with an applied magnetic field. However, when prepared as single crystals but with excess of the rare earths they become spontaneously ferromagnets due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in addition to the superexchange mechanisms. On such ferromagnetic compositions of TbN and GdN and also in EuB 6 a new magneto-optic effect has been discovered, a spontaneous blue shift of the plasma edge upon magnetic order. The plasma edge is measured with optical reflectivity and it depends on the free carrier concentration. In other words the free carrier concentration increases upon ferromagnetic order. This effect can be understood with the spontaneous exchange splitting of mainly the 5d conduction band, lowering the bottom of the spin up 5d band, thus increasing the indirect overlap with the valence p band of the anions and thus enhancing the carrier concentration. This blue shift of the plasma edge follows a spin correlation function. An external magnetic field applied near TC enhances the blue shift since the magnetization is not yet saturated. For T→0 a magnetic field has no effect since the magnetization is spontaneously saturated

Spin-chirality decoupling in Heisenberg spin glasses and related systems

OpenAIRE

Kawamura, Hikaru

2006-01-01

Recent studies on the spin and the chirality orderings of the three-dimensional Heisenberg spin glass and related systems are reviewed with particular emphasis on the possible spin-chirality decoupling phenomena. Chirality scenario of real spin-glass transition and its experimental consequence on the ordering of Heisenberg-like spin glasses are discussed.

Spin current

CERN Document Server

Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

2012-01-01

In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

Giant spin torque in systems with anisotropic exchange interaction

OpenAIRE

Korenev, Vladimir L.

2012-01-01

Control of magnetic domain wall movement by the spin-polarized current looks promising for creation of a new generation of magnetic memory devices. A necessary condition for this is the domain wall shift by a low-density current. Here I show that a strongly anisotropic exchange interaction between mobile heavy holes and localized magnetic moments enormously increases the current-induced torque on the domain wall as compared to systems with isotropic exchange. This enables one to control the d...

Spin current

CERN Document Server

Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

2017-01-01

Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

National Register Historic Districts

Data.gov (United States)

Iowa State University GIS Support and Research Facility — The National Register Historic District layer is a shape file showing the boundaries of Historic Districts that are listed on the National Register of Historic Places.

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.

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

The influence of the Rashba spin-orbit coupling on the two-dimensional magnetoexcitons

International Nuclear Information System (INIS)

Hakioglu, T; Liberman, M A; Moskalenko, S A; Podlesny, I V

2011-01-01

The influence of the Rashba spin-orbit coupling (RSOC) on the two-dimensional (2D) electrons and holes in a strong perpendicular magnetic field leads to different results for the Landau quantization in different spin projections. In the Landau gauge the unidimensional wave vector describing the free motion in one in-plane direction is the same for both spin projections, whereas the numbers of Landau quantization levels are different. For an electron in an s-type conduction band they differ by one, as was established earlier by Rashba (1960 Fiz. Tverd. Tela 2 1224), whereas for heavy holes in a p-type valence band influenced by the 2D symmetry of the layer they differ by three. The shifts and the rearrangements of the 2D hole Landau quantization levels on the energy scale are much larger in comparison with the case of conduction electron Landau levels. This is due to the strong influence of the magnetic field on the RSOC parameter. At sufficiently large values of this parameter the shifts and rearrangements are comparable with the hole cyclotron energy. There are two lowest spin-split Landau levels for electrons as well as four lowest ones for holes in the case of small RSOC parameters. They give rise to eight lowest energy bands of the 2D magnetoexcitons, as well as of the band-to-band quantum transitions. It is shown that three of them are dipole-active, three are quadrupole-active and two are forbidden. The optical orientation under the influence of circularly polarized light leads to optical alignment of the magnetoexcitons with different orbital momentum projections in the direction of the external magnetic field. (paper)

Rapid shifts in catch composition in the artisanal Red Sea reef fisheries of Eritrea

NARCIS (Netherlands)

Tsehaye, I.W.; Machiels, M.A.M.; Nagelkerke, L.A.J.

2007-01-01

Shifts in catch composition were registered in the Eritrean artisanal fisheries, which were launched into a renewed development after the end of the independence war in 1991. Our analysis of catch and effort data showed that total fishing effort as well as total annual catch increased more than

Competing Spin Liquids and Hidden Spin-Nematic Order in Spin Ice with Frustrated Transverse Exchange

Directory of Open Access Journals (Sweden)

Mathieu Taillefumier

2017-12-01

Full Text Available Frustration in magnetic interactions can give rise to disordered ground states with subtle and beautiful properties. The spin ices Ho_{2}Ti_{2}O_{7} and Dy_{2}Ti_{2}O_{7} exemplify this phenomenon, displaying a classical spin-liquid state, with fractionalized magnetic-monopole excitations. Recently, there has been great interest in closely related “quantum spin-ice” materials, following the realization that anisotropic exchange interactions could convert spin ice into a massively entangled, quantum spin liquid, where magnetic monopoles become the charges of an emergent quantum electrodynamics. Here we show that even the simplest model of a quantum spin ice, the XXZ model on the pyrochlore lattice, can realize a still-richer scenario. Using a combination of classical Monte Carlo simulation, semiclassical molecular-dynamics simulation, and analytic field theory, we explore the properties of this model for frustrated transverse exchange. We find not one, but three competing forms of spin liquid, as well as a phase with hidden, spin-nematic order. We explore the experimental signatures of each of these different states, making explicit predictions for inelastic neutron scattering. These results show an intriguing similarity to experiments on a range of pyrochlore oxides.

Separating inverse spin Hall voltage and spin rectification voltage by inverting spin injection direction

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wenxu, E-mail: xwzhang@uestc.edu.cn; Peng, Bin; Han, Fangbin; Wang, Qiuru; Zhang, Wanli [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Soh, Wee Tee; Ong, Chong Kim [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore)

2016-03-07

We develop a method for universally resolving the important issue of separating the inverse spin Hall effect (ISHE) from the spin rectification effect (SRE) signal. This method is based on the consideration that the two effects depend on the spin injection direction: The ISHE is an odd function of the spin injection direction while the SRE is independent on it. Thus, the inversion of the spin injection direction changes the ISHE voltage signal, while the SRE voltage remains. It applies generally to analyzing the different voltage contributions without fitting them to special line shapes. This fast and simple method can be used in a wide frequency range and has the flexibility of sample preparation.

Quantum dynamics of nuclear spins and spin relaxation in organic semiconductors

Science.gov (United States)

Mkhitaryan, V. V.; Dobrovitski, V. V.

2017-06-01

We investigate the role of the nuclear-spin quantum dynamics in hyperfine-induced spin relaxation of hopping carriers in organic semiconductors. The fast-hopping regime, when the carrier spin does not rotate much between subsequent hops, is typical for organic semiconductors possessing long spin coherence times. We consider this regime and focus on a carrier random-walk diffusion in one dimension, where the effect of the nuclear-spin dynamics is expected to be the strongest. Exact numerical simulations of spin systems with up to 25 nuclear spins are performed using the Suzuki-Trotter decomposition of the evolution operator. Larger nuclear-spin systems are modeled utilizing the spin-coherent state P -representation approach developed earlier. We find that the nuclear-spin dynamics strongly influences the carrier spin relaxation at long times. If the random walk is restricted to a small area, it leads to the quenching of carrier spin polarization at a nonzero value at long times. If the random walk is unrestricted, the carrier spin polarization acquires a long-time tail, decaying as 1 /√{t } . Based on the numerical results, we devise a simple formula describing the effect quantitatively.

Electrical Manipulation of Donor Spin Qubits in Silicon and Germanium

Science.gov (United States)

Sigillito, Anthony James

single-phonon T1 process. At lower frequencies or lower temperatures the qubit coherence times should substantially increase. Finally, we measure the electric field tunability of donors in germanium and find a four order-of-magnitude enhancement in the spin-orbit Stark shift and confirm that the donors should be tunable by at least 4 times the electron spin ensemble linewidth (in isotopically enriched material). Germanium should therefore also be more sensitive to electrically driven nuclear magnetic resonance. Based on these results germanium is a promising alternative to silicon for spin qubits.

The experience of being a shift-leader in a hospital ward.

Science.gov (United States)

Goldblatt, Hadass; Granot, Michal; Admi, Hanna; Drach-Zahavy, Anat

2008-07-01

This paper is a report of a study to explore the experience of being a shift-leader, and how these nurses view the management of their shift. Professional demands on skilled and capable shift-leaders, who competently handle multi-disciplinary staff and patients, as well as operations and information, call for the development of efficient nursing leadership roles. Nevertheless, knowledge of shift-leaders' perspectives concerning their task management and leadership styles is relatively limited. Twenty-eight Registered Nurses working in an Israeli medical centre participated in this qualitative study. Data were gathered through in-depth interviews conducted in two phases between February and October 2005: three focus group interviews (phase 1) followed by seven individual interviews (phase 2). Content analysis revealed two major themes which constitute the essence of being a shift-leader: (1) a burden of responsibility, where the shift-leader moves between positions of maximum control and delegating some responsibility to other nurses; (2) the role's temporal dimension, expressed as a strong desire to reach the end of the shift safely, and taking managerial perspectives beyond the boundaries of the specific shift. The core of the shift-leader's position is an immense sense of responsibility. However, this managerial role is transient and therefore lacks an established authority. A two-dimensional taxonomy of these themes reveals four types of potential and actual coping among shift-leaders, indicating the need to train them in leadership skills and systemic thinking. Interventions to limit the potential stress hazards should be focused simultaneously on shift-leaders themselves and on job restructuring.

NMR relaxation rates and Knight shifts in the alloy Mg1-xAlxB2

International Nuclear Information System (INIS)

Serventi, S; Allodi, G; Bucci, C; Renzi, R De; Guidi, G; Pavarini, E; Manfrinetti, P; Palenzona, A

2003-01-01

We measured the 27 Al and 11 B NMR spin lattice relaxation rates and the isotropic Knight shifts in powder samples of Mg 1-x Al x B 2 , as a function of the Al concentration, x. The temperature independence of the Knight shifts and the linear temperature dependence of the relaxation are verified throughout the compositions explored. The variation with x of the measured quantities is discussed in terms of the projected densities of states at the Fermi energy, finding good qualitative as well as quantitative agreement with recent band structure calculations

Chaotic spin exchange: is the spin non-flip rate observable?

International Nuclear Information System (INIS)

Senba, Masayoshi

1994-01-01

If spin exchange is of the Poisson nature, that is, if the time distribution of collisions obeys an exponential distribution function and the collision process is random, the muon spin depolarization is determined only by the spin flip rate regardless of the spin non-flip rate. In this work, spin exchange is discussed in the case of chaotic spin exchange, where the distribution of collision time sequences, generated by a deterministic equation, is exponential but not random (deterministic chaos). Even though this process has the same time distribution as a Poisson process, the muon polarization is affected by the spin non-flip rate. Having an exponential time distribution function is not a sufficient condition for the non-observation of the spin non-flip rate and it is essential that the process is also random. (orig.)

Field-free deterministic ultrafast creation of magnetic skyrmions by spin-orbit torques

Science.gov (United States)

Büttner, Felix; Lemesh, Ivan; Schneider, Michael; Pfau, Bastian; Günther, Christian M.; Hessing, Piet; Geilhufe, Jan; Caretta, Lucas; Engel, Dieter; Krüger, Benjamin; Viefhaus, Jens; Eisebitt, Stefan; Beach, Geoffrey S. D.

2017-11-01

Magnetic skyrmions are stabilized by a combination of external magnetic fields, stray field energies, higher-order exchange interactions and the Dzyaloshinskii-Moriya interaction (DMI). The last favours homochiral skyrmions, whose motion is driven by spin-orbit torques and is deterministic, which makes systems with a large DMI relevant for applications. Asymmetric multilayers of non-magnetic heavy metals with strong spin-orbit interactions and transition-metal ferromagnetic layers provide a large and tunable DMI. Also, the non-magnetic heavy metal layer can inject a vertical spin current with transverse spin polarization into the ferromagnetic layer via the spin Hall effect. This leads to torques that can be used to switch the magnetization completely in out-of-plane magnetized ferromagnetic elements, but the switching is deterministic only in the presence of a symmetry-breaking in-plane field. Although spin-orbit torques led to domain nucleation in continuous films and to stochastic nucleation of skyrmions in magnetic tracks, no practical means to create individual skyrmions controllably in an integrated device design at a selected position has been reported yet. Here we demonstrate that sub-nanosecond spin-orbit torque pulses can generate single skyrmions at custom-defined positions in a magnetic racetrack deterministically using the same current path as used for the shifting operation. The effect of the DMI implies that no external in-plane magnetic fields are needed for this aim. This implementation exploits a defect, such as a constriction in the magnetic track, that can serve as a skyrmion generator. The concept is applicable to any track geometry, including three-dimensional designs.

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

Shot noise of spin current and spin transfer torque

International Nuclear Information System (INIS)

Yu Yunjin; Zhan Hongxin; Wan Langhui; Wang Bin; Wei Yadong; Sun Qingfeng; Wang Jian

2013-01-01

We report the theoretical investigation of the shot noise of the spin current (S σ ) and the spin transfer torque (S τ ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear S σ − V and S τ − V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage N τ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque N τ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period N τ (θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters. (paper)

Paramagnetic material for quantum information processing: electronic and nuclear spins manipulations in β - Ga2O3: Ti

International Nuclear Information System (INIS)

Mentink-Vigier, Frederic

2011-01-01

Quantum information processing is a major challenge both on fundamental and technological grounds. In this research field, the spin bus concept relies on the use of both the electronic and nuclear spins in which the electron is used as a reading and writing head over the nuclei system which makes the qubit register. The requested material to build a spin bus must have unpaired electrons delocalized over a great number of nuclear spins having long decoherence time. In this work, we studied a spin system composed of titanium (III) interacting with multiple gallium nuclei in gallium oxide. We synthesized and studied the titanium paramagnetic center in gallium oxide single crystals by continuous wave EPR and ENDOR spectroscopy and showed that the electron is delocalized over eight neighbouring gallium nuclei. This study also revealed a strong isotopic effect on the nucleus-nucleus interaction mediated by the electron. When the two nearest gallium nuclei surrounding the titanium are identical (same isotopes) this interaction is one order of magnitude higher than in the case of inequivalent nuclei. This effect can be used in order to reduce the computation time. Finally, the dynamical properties of the spin system have been characterized by pulsed EPR and ENDOR spectroscopy. The electron spin decoherence is driven by instantaneous and spectral diffusion. The nuclear dynamical properties have also been studied in order to determine the order of magnitude of nuclear spin relaxation and decoherence time. (author) [fr

Solid state NMR of spin-1/2 nuclei

International Nuclear Information System (INIS)

Wind, R.A.

1991-01-01

The detection of nuclear magnetic resonance by Bloch et al. and Purcell and co-workers in 1946 has led to the development of one of the most powerful spectroscopic techniques known today. The reason is that, besides the applied external magnetic field, a nuclear spin also experiences extra local magnetic fields, which are due to surrounding electron clouds (the chemical shift) and other spins. These local fields differ for nuclei located at chemically different positions in a molecule. The result is that an NMR spectrum often consists of several lines, which can be considered to be a fingerprint of the material under investigation an can assist the clarifying its molecular structure. NMR has been especially successful in liquids and liquid like materials, where fast molecular tumblings average out the anisotropies in the local fields, resulting in well-resolved NMR spectra. This paper reports that initially the development of solid-state NMR was less dramatic. Originally, for reasons of sensitivity, attention was focused mainly on 1 H NMR. The result is that the NMR spectrum usually consists of single, broad, featureless line, which, except for special cases such as more or less isolated spin pairs or methyl groups, does not provide much information

Relating timed and register automata

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Diego Figueira

2010-11-01

Full Text Available Timed automata and register automata are well-known models of computation over timed and data words respectively. The former has clocks that allow to test the lapse of time between two events, whilst the latter includes registers that can store data values for later comparison. Although these two models behave in appearance differently, several decision problems have the same (undecidability and complexity results for both models. As a prominent example, emptiness is decidable for alternating automata with one clock or register, both with non-primitive recursive complexity. This is not by chance. This work confirms that there is indeed a tight relationship between the two models. We show that a run of a timed automaton can be simulated by a register automaton, and conversely that a run of a register automaton can be simulated by a timed automaton. Our results allow to transfer complexity and decidability results back and forth between these two kinds of models. We justify the usefulness of these reductions by obtaining new results on register automata.

SU (N ) spin-wave theory: Application to spin-orbital Mott insulators

Science.gov (United States)

Dong, Zhao-Yang; Wang, Wei; Li, Jian-Xin

2018-05-01

We present the application of the SU (N ) spin-wave theory to spin-orbital Mott insulators whose ground states exhibit magnetic orders. When taking both spin and orbital degrees of freedom into account rather than projecting Hilbert space onto the Kramers doublet, which is the lowest spin-orbital locked energy levels, the SU (N ) spin-wave theory should take the place of the SU (2 ) one due to the inevitable spin-orbital multipole exchange interactions. To implement the application, we introduce an efficient general local mean-field method, which involves all local fluctuations, and develop the SU (N ) linear spin-wave theory. Our approach is tested firstly by calculating the multipolar spin-wave spectra of the SU (4 ) antiferromagnetic model. Then, we apply it to spin-orbital Mott insulators. It is revealed that the Hund's coupling would influence the effectiveness of the isospin-1 /2 picture when the spin-orbital coupling is not large enough. We further carry out the SU (N ) spin-wave calculations of two materials, α -RuCl3 and Sr2IrO4 , and find that the magnonic and spin-orbital excitations are consistent with experiments.

Spin-inversion in nanoscale graphene sheets with a Rashba spin-orbit barrier

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Somaieh Ahmadi

2012-03-01

Full Text Available Spin-inversion properties of an electron in nanoscale graphene sheets with a Rashba spin-orbit barrier is studied using transfer matrix method. It is found that for proper values of Rashba spin-orbit strength, perfect spin-inversion can occur in a wide range of electron incident angle near the normal incident. In this case, the graphene sheet with Rashba spin-orbit barrier can be considered as an electron spin-inverter. The efficiency of spin-inverter can increase up to a very high value by increasing the length of Rashba spin-orbit barrier. The effect of intrinsic spin-orbit interaction on electron spin inversion is then studied. It is shown that the efficiency of spin-inverter decreases slightly in the presence of intrinsic spin-orbit interaction. The present study can be used to design graphene-based spintronic devices.

Spin-pump-induced spin transport in a thermally evaporated pentacene film

Energy Technology Data Exchange (ETDEWEB)

Tani, Yasuo; Shikoh, Eiji, E-mail: shikoh@elec.eng.osaka-cu.ac.jp [Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Teki, Yoshio [Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

2015-12-14

We report the spin-pump-induced spin transport properties of a pentacene film prepared by thermal evaporation. In a palladium(Pd)/pentacene/Ni{sub 80}Fe{sub 20} tri-layer sample, a pure spin-current is generated in the pentacene layer by the spin-pumping of Ni{sub 80}Fe{sub 20}, which is independent of the conductance mismatch problem in spin injection. The spin current is absorbed into the Pd layer, converted into a charge current with the inverse spin-Hall effect in Pd, and detected as an electromotive force. This is clear evidence for the pure spin current at room temperature in pentacene films prepared by thermal evaporation.

Practical use of chemical shift databases for protein solid-state NMR: 2D chemical shift maps and amino-acid assignment with secondary-structure information

International Nuclear Information System (INIS)

Fritzsching, K. J.; Yang, Y.; Schmidt-Rohr, K.; Hong Mei

2013-01-01

We introduce a Python-based program that utilizes the large database of 13 C and 15 N chemical shifts in the Biological Magnetic Resonance Bank to rapidly predict the amino acid type and secondary structure from correlated chemical shifts. The program, called PACSYlite Unified Query (PLUQ), is designed to help assign peaks obtained from 2D 13 C– 13 C, 15 N– 13 C, or 3D 15 N– 13 C– 13 C magic-angle-spinning correlation spectra. We show secondary-structure specific 2D 13 C– 13 C correlation maps of all twenty amino acids, constructed from a chemical shift database of 262,209 residues. The maps reveal interesting conformation-dependent chemical shift distributions and facilitate searching of correlation peaks during amino-acid type assignment. Based on these correlations, PLUQ outputs the most likely amino acid types and the associated secondary structures from inputs of experimental chemical shifts. We test the assignment accuracy using four high-quality protein structures. Based on only the Cα and Cβ chemical shifts, the highest-ranked PLUQ assignments were 40–60 % correct in both the amino-acid type and the secondary structure. For three input chemical shifts (CO–Cα–Cβ or N–Cα–Cβ), the first-ranked assignments were correct for 60 % of the residues, while within the top three predictions, the correct assignments were found for 80 % of the residues. PLUQ and the chemical shift maps are expected to be useful at the first stage of sequential assignment, for combination with automated sequential assignment programs, and for highly disordered proteins for which secondary structure analysis is the main goal of structure determination.

Spin-Triplet Pairing Induced by Spin-Singlet Interactions in Noncentrosymmetric Superconductors

Science.gov (United States)

Matsuzaki, Tomoaki; Shimahara, Hiroshi

2017-02-01

In noncentrosymmetric superconductors, we examine the effect of the difference between the intraband and interband interactions, which becomes more important when the band splitting increases. We define the difference ΔVμ between their coupling constants, i.e., that between the intraband and interband hopping energies of intraband Cooper pairs. Here, the subscript μ of ΔVμ indicates that the interactions scatter the spin-singlet and spin-triplet pairs when μ = 0 and μ = 1,2,3, respectively. It is shown that the strong antisymmetric spin-orbit interaction reverses the target spin parity of the interaction: it converts the spin-singlet and spin-triplet interactions represented by ΔV0 and ΔVμ>0 into effective spin-triplet and spin-singlet pairing interactions, respectively. Hence, for example, triplet pairing can be induced solely by the singlet interaction ΔV0. We name the pairing symmetry of the system after that of the intraband Cooper pair wave function, but with an odd-parity phase factor excluded. The pairing symmetry must then be even, even for the triplet component, and the following results are obtained. When ΔVμ is small, the spin-triplet p-wave interactions induce spin-triplet s-wave and spin-triplet d-wave pairings in the regions where the repulsive singlet s-wave interaction is weak and strong, respectively. When ΔV0 is large, a repulsive interband spin-singlet interaction can stabilize spin-triplet pairing. When the Rashba interaction is adopted for the spin-orbit interaction, the spin-triplet pairing interactions mediated by transverse magnetic fluctuations do not contribute to triplet pairing.

Night shift work characteristics and occupational co-exposures in industrial plants in Łódź, Poland

Directory of Open Access Journals (Sweden)

Beata Pepłońska

2013-08-01

Full Text Available Objectives: Night shift work involving circadian rhythm disruption has been classified by IARC as a probably carcinogenic to humans (Group 2A. Little is known about co-exposures of the night shift work in occupational settings. The aim of our study was to characterize night shift work systems and industrial exposures occurring in the manufacturing plants in Łódź, Poland, where night shift work system operates, with particular focus on potential carcinogens. Material and Methods: Data on the night shift work systems and hazardous agents were collected through survey performed in 44 enterprises. The identified hazardous agents were checked using the IARC carcinogen list, and the harmonized EU classification of chemical substances. We also examined databases of the Central Register of Data on exposure to substances, preparations, agents and technological processes showing carcinogenic or mutagenic properties in Poland. Results: The most common system of work among studied enterprises employed 3 (8-hour shifts within a 5-day cycle. We identified as many as 153 hazards occurring in the environment of the plants, with noise, carbon monoxide and formaldehyde recorded as the most common ones. Out of these hazards, 11 agents have been classified by IARC to group 1 - carcinogenic to humans, whereas 10 agents have been classified as carcino - gens by the regulation of European Classification of carcinogens. Analysis of the data from the Central Register revealed that 6 plants reported presence of carcinogens in the environment of work. Conclusions: In our study we observed that in none of the workplaces the night shift work was a single exposure. Further epidemiological studies focusing on investigation of health effects of the night shift work should identify occupational co -exposures and examine them as potential confounders.

Dynamical spin accumulation in large-spin magnetic molecules

Science.gov (United States)

Płomińska, Anna; Weymann, Ireneusz; Misiorny, Maciej

2018-01-01

The frequency-dependent transport through a nanodevice containing a large-spin magnetic molecule is studied theoretically in the Kondo regime. Specifically, the effect of magnetic anisotropy on dynamical spin accumulation is of primary interest. Such accumulation arises due to finite components of frequency-dependent conductance that are off diagonal in spin. Here, employing the Kubo formalism and the numerical renormalization group method, we demonstrate that the dynamical transport properties strongly depend on the relative orientation of spin moments in electrodes of the device, as well as on intrinsic parameters of the molecule. In particular, the effect of dynamical spin accumulation is found to be greatly affected by the type of magnetic anisotropy exhibited by the molecule, and it develops for frequencies corresponding to the Kondo temperature. For the parallel magnetic configuration of the device, the presence of dynamical spin accumulation is conditioned by the interplay of ferromagnetic-lead-induced exchange field and the Kondo correlations.

Optimizing Instruction Scheduling and Register Allocation for Register-File-Connected Clustered VLIW Architectures

Science.gov (United States)

Tang, Haijing; Wang, Siye; Zhang, Yanjun

2013-01-01

Clustering has become a common trend in very long instruction words (VLIW) architecture to solve the problem of area, energy consumption, and design complexity. Register-file-connected clustered (RFCC) VLIW architecture uses the mechanism of global register file to accomplish the inter-cluster data communications, thus eliminating the performance and energy consumption penalty caused by explicit inter-cluster data move operations in traditional bus-connected clustered (BCC) VLIW architecture. However, the limit number of access ports to the global register file has become an issue which must be well addressed; otherwise the performance and energy consumption would be harmed. In this paper, we presented compiler optimization techniques for an RFCC VLIW architecture called Lily, which is designed for encryption systems. These techniques aim at optimizing performance and energy consumption for Lily architecture, through appropriate manipulation of the code generation process to maintain a better management of the accesses to the global register file. All the techniques have been implemented and evaluated. The result shows that our techniques can significantly reduce the penalty of performance and energy consumption due to access port limitation of global register file. PMID:23970841

Optimizing Instruction Scheduling and Register Allocation for Register-File-Connected Clustered VLIW Architectures

Directory of Open Access Journals (Sweden)

Haijing Tang

2013-01-01

Full Text Available Clustering has become a common trend in very long instruction words (VLIW architecture to solve the problem of area, energy consumption, and design complexity. Register-file-connected clustered (RFCC VLIW architecture uses the mechanism of global register file to accomplish the inter-cluster data communications, thus eliminating the performance and energy consumption penalty caused by explicit inter-cluster data move operations in traditional bus-connected clustered (BCC VLIW architecture. However, the limit number of access ports to the global register file has become an issue which must be well addressed; otherwise the performance and energy consumption would be harmed. In this paper, we presented compiler optimization techniques for an RFCC VLIW architecture called Lily, which is designed for encryption systems. These techniques aim at optimizing performance and energy consumption for Lily architecture, through appropriate manipulation of the code generation process to maintain a better management of the accesses to the global register file. All the techniques have been implemented and evaluated. The result shows that our techniques can significantly reduce the penalty of performance and energy consumption due to access port limitation of global register file.

Hardy's argument and successive spin-s measurements

International Nuclear Information System (INIS)

Ahanj, Ali

2010-01-01

We consider a hidden-variable theoretic description of successive measurements of noncommuting spin observables on an input spin-s state. In this scenario, the hidden-variable theory leads to a Hardy-type argument that quantum predictions violate it. We show that the maximum probability of success of Hardy's argument in quantum theory is ((1/2)) 4s , which is more than in the spatial case.

Large spin current injection in nano-pillar-based lateral spin valve

Energy Technology Data Exchange (ETDEWEB)

Nomura, Tatsuya [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan)

2016-08-26

We have investigated the influence of the injection of a large pure spin current on a magnetization process of a non-locally located ferromagnetic dot in nano-pillar-based lateral spin valves. Here, we prepared two kinds of the nano-pillar-type lateral spin valve based on Py nanodots and CoFeAl nanodots fabricated on a Cu film. In the Py/Cu lateral spin valve, although any significant change of the magnetization process of the Py nanodot has not been observed at room temperature. The magnetization reversal process is found to be modified by injecting a large pure spin current at 77 K. Switching the magnetization by the nonlocal spin injection has also been demonstrated at 77 K. In the CoFeAl/Cu lateral spin valve, a room temperature spin valve signal was strongly enhanced from the Py/Cu lateral spin valve because of the highly spin-polarized CoFeAl electrodes. The room temperature nonlocal switching has been demonstrated in the CoFeAl/Cu lateral spin valve.

Moessbauer effect study of charge and spin transfer in Fe-Cr

International Nuclear Information System (INIS)

Dubiel, S.M.; Zukrowski, J.

1981-01-01

The influence of temperature and time of annealing on hyperfine fields and isomer shifts has been studied for a range of Fe-Cr alloys containing 1-45 at% Cr. It has been revealed that up to 15 at% Cr neither time or temperature of annealing practically does affect the hyperfine parameters. For more concentrated samples, however, both temperature and time of annealing are important. In particular, the Moessbauer spectrum of Fe-45.5 at% Cr annealed at 700 0 C for 5 h was a single-line indicating that the sample was paramagnetic. The observed changes of the hyperfine fields and the isomer shifts have been interpreted in terms of a spin and charge transfer, respectively. Strong linear correlations between the following quantities have been revealed: the hyperfine field H(0,0) and the isomer shift IS(0,0); the average hyperfine field anti H and the average isomer shift anti Ianti S; the average hyperfine field anti H and the average number of Cr atoms in the first two coordination spheres, anti N. It has been calculated from the first two correlations that a) a change of polarization of itinerant s-like electrons of one electron is equivalent to a change of the hyperfine field of 1602 kOe, and b) on average, a unit change of s-like electron polarization is equivalent to 3277 kOe. The two constants are very close to theoretical estimations, which can be found in literature. Correlation between the hyperfine field and the isomer shift led to a conclusion that the substitution of Fe atoms by Cr ones decreases the density of spin-up electrons on average by 0.026 electrons per one Cr atom in a unit cell. These electrons are most likely trapped by Cr atoms, because the hyperfine field at neighbouring Fe nuclei decreases and the density of charge at those nuclei increases at the rate of 0.029 electrons per one Cr atom in a unit cell. (orig./BHO)

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

The Copenhagen School Health Records Register

DEFF Research Database (Denmark)

Baker, Jennifer L; Sørensen, Thorkild I A

2011-01-01

The Copenhagen School Health Records Register is an electronic register of health examination information on 372,636 children who attended school in Copenhagen, Denmark from 1936 to 2005.......The Copenhagen School Health Records Register is an electronic register of health examination information on 372,636 children who attended school in Copenhagen, Denmark from 1936 to 2005....

The Danish Adoption Register

DEFF Research Database (Denmark)

Petersen, Liselotte; Sørensen, Thorkild I A

2011-01-01

The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia.......The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia....

Spin-orbit induced electronic spin separation in semiconductor nanostructures.

Science.gov (United States)

Kohda, Makoto; Nakamura, Shuji; Nishihara, Yoshitaka; Kobayashi, Kensuke; Ono, Teruo; Ohe, Jun-ichiro; Tokura, Yasuhiro; Mineno, Taiki; Nitta, Junsaku

2012-01-01

The demonstration of quantized spin splitting by Stern and Gerlach is one of the most important experiments in modern physics. Their discovery was the precursor of recent developments in spin-based technologies. Although electrical spin separation of charged particles is fundamental in spintronics, in non-uniform magnetic fields it has been difficult to separate the spin states of charged particles due to the Lorentz force, as well as to the insufficient and uncontrollable field gradients. Here we demonstrate electronic spin separation in a semiconductor nanostructure. To avoid the Lorentz force, which is inevitably induced when an external magnetic field is applied, we utilized the effective non-uniform magnetic field which originates from the Rashba spin-orbit interaction in an InGaAs-based heterostructure. Using a Stern-Gerlach-inspired mechanism, together with a quantum point contact, we obtained field gradients of 10(8) T m(-1) resulting in a highly polarized spin current.

Spin heat capacity of monolayer and AB-stacked bilayer MoS2 in the presence of exchange magnetic field

Science.gov (United States)

Hoi, Bui Dinh; Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos

2017-04-01

Dirac theory and Green's function technique are carried out to compute the spin dependent band structures and corresponding electronic heat capacity (EHC) of monolayer (ML) and AB-stacked bilayer (BL) molybdenum disulfide (MoS2) two-dimensional (2D) crystals. We report the influence of induced exchange magnetic field (EMF) by magnetic insulator substrates on these quantities for both structures. The spin-up (down) subband gaps are shifted with EMF from conduction (valence) band to valence (conduction) band at both Dirac points in the ML because of the spin-orbit coupling (SOC) which leads to a critical EMF in the K point and EHC returns to its initial states for both spins. In the BL case, EMF results split states and the decrease (increase) behavior of spin-up (down) subband gaps has been observed at both K and K‧ valleys which is due to the combined effect of SOC and interlayer coupling. For low and high EMFs, EHC of BL MoS2 does not change for spin-up subbands while increases for spin-down subbands.

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)

Work schedule flexibility is associated with emotional exhaustion among registered nurses in Swiss hospitals: A cross-sectional study.

Science.gov (United States)

Dhaini, Suzanne R; Denhaerynck, Kris; Bachnick, Stefanie; Schwendimann, René; Schubert, Maria; De Geest, Sabina; Simon, Michael

2018-06-01

Emotional exhaustion among healthcare workers is a widely investigated, well-recognized problem, the incidence of which has recently been linked to work environment factors, particularly work/family conflict. However, another environmental feature that may be equally influential, but that is more amenable to nurse manager action, remains less recognized: shift schedule flexibility. This study's main purposes were to assess variations in work schedule flexibility between Swiss acute care hospital units, and to investigate associations between psychosocial work environment (e.g. work schedule flexibility) and self-reported emotional exhaustion among registered nurses. This is a secondary analysis of data collected for the multi-center observational cross-sectional Match RN study, which included a national sample of 23 hospitals and 1833 registered nurses across Switzerland. Overall, self-reported work schedule flexibility among registered nurses was limited: 32% of participants reported little or no influence in planning their own shifts. Work schedule flexibility (β -0.11; CI -0.16; -0.06) and perceived nurse manager ability (β -0.30; CI -0.49; -0.10) were negatively related to self-reported emotional exhaustion. Work-family conflict (β 0.39; CI 0.33; 0.45) was positively correlated to emotional exhaustion. The study results indicate that managerial efforts to improve working environments, including special efforts to improve work schedule flexibility, might play an important role in promoting nurses' emotional health. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative Aspects of Spin-Dependent Interaction Potentials for Spin-1/2 and Spin-1 Matter Fields

Directory of Open Access Journals (Sweden)

P. C. Malta

2016-01-01

Full Text Available This paper sets out to establish a comparative study between classes of spin- and velocity-dependent potentials for spin-1/2 and spin-1 matter currents/sources in the nonrelativistic regime. Both (neutral massive scalar and vector particles are considered to mediate the interactions between (pseudo-scalar sources or (pseudo-vector currents. Though our discussion is more general, we contemplate specific cases in which our results may describe the electromagnetic interaction with a massive (Proca-type photon exchanged between two spin-1/2 or two spin-1 carriers. We highlight the similarities and peculiarities of the potentials for the two different types of charged matter and also focus our attention on the comparison between the particular aspects of two different field representations for spin-1 matter particles. We believe that our results may contribute to a further discussion of the relation between charge, spin, and extensibility of elementary particles.

Heat and spin interconversion

International Nuclear Information System (INIS)

Ohnuma, Yuichi; Matsuo, Mamoru; Maekawa, Sadamichi; Saitoh, Eeiji

2017-01-01

Spin Seebeck and spin Peltier effects, which are mutual conversion phenomena of heat and spin, are discussed on the basis of the microscopic theory. First, the spin Seebeck effect, which is the spin-current generation due to heat current, is discussed. The recent progress in research on the spin Seebeck effect are introduced. We explain the origin of the observed sign changes of the spin Seebeck effect in compensated ferromagnets. Next, the spin Peltier effect, which is the heat-current generation due to spin current, is discussed. Finally, we show that the spin Seebeck and spin Peltier effects are summarized by Onsager's reciprocal relation and derive Kelvin's relation for the spin and heat transports. (author)

Phosphorus-doped thin silica films characterized by magic-angle spinning nuclear magnetic resonance spectroscopy

DEFF Research Database (Denmark)

Jacobsen, H.J.; Skibsted, J.; Kristensen, Martin

2001-01-01

Magic-angle spinning nuclear magnetic resonance spectra of 31P and 29Si have been achieved for a thin silica film doped with only 1.8% 31P and deposited by plasma enhanced chemical vapor deposition on a pure silicon wafer. The observation of a symmetric 31P chemical shift tensor is consistent...

Rotational Invariance of the 2d Spin - Spin Correlation Function

Science.gov (United States)

Pinson, Haru

2012-09-01

At the critical temperature in the 2d Ising model on the square lattice, we establish the rotational invariance of the spin-spin correlation function using the asymptotics of the spin-spin correlation function along special directions (McCoy and Wu in the two dimensional Ising model. Harvard University Press, Cambridge, 1973) and the finite difference Hirota equation for which the spin-spin correlation function is shown to satisfy (Perk in Phys Lett A 79:3-5, 1980; Perk in Proceedings of III international symposium on selected topics in statistical mechanics, Dubna, August 22-26, 1984, JINR, vol II, pp 138-151, 1985).

Electric-field tunable spin waves in PMN-PT/NiFe heterostructure: Experiment and micromagnetic simulations

Energy Technology Data Exchange (ETDEWEB)

Ziȩtek, Slawomir, E-mail: zietek@agh.edu.pl [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Chȩciński, Jakub [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059 Kraków (Poland); Frankowski, Marek; Skowroński, Witold; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland)

2017-04-15

We present a comprehensive theoretical and experimental study of voltage-controlled standing spin waves resonance (SSWR) in PMN-PT/NiFe multiferroic heterostructures patterned into microstrips. A spin-diode technique was used to observe ferromagnetic resonance (FMR) mode and SSWR in NiFe strip mechanically coupled with a piezoelectric substrate. Application of an electric field to a PMN-PT creates a strain in permalloy and thus shifts the FMR and SSWR fields due to the magnetostriction effect. The experimental results are compared with micromagnetic simulations and a good agreement between them is found for dynamics of FMR and SSWR with and without electric field. Moreover, micromagnetic simulations enable us to discuss the amplitude and phase spatial distributions of FMR and SSWR modes, which are not directly observable by means of spin diode detection technique.

Short-term effects of night shift work on breast cancer risk

DEFF Research Database (Denmark)

Vistisen, H. T.; Garde, A. H.; Frydenberg, M.

2017-01-01

.80-1.01] was observed for workers ever working night shifts during the follow-up period compared with workers only working day shifts after adjustment for age, age at first child, parity, family history of breast or ovarian cancer, sex hormones, medications related to alcoholism, family educational level, mammography......Objectives: The objective was to examine if night shift work is a short-term risk factor for breast cancer, including combined estrogen receptor (ER) and human epidermal growth factor 2 (HER2) breast cancer subtypes. Methods: The cohort comprised 155 540 public sector female workers in Denmark who...... were followed from 2007-2012. Day-to-day work-hour information was available from payroll registers and 1245 incident cases of breast cancer were identified in national cancer registries together with receptor subtype information. Results: A rate ratio (RR) of 0.90 [95% confidence interval (95% CI) 0...

Spin-independent transparency of pure spin current at normal/ferromagnetic metal interface

Science.gov (United States)

Hao, Runrun; Zhong, Hai; Kang, Yun; Tian, Yufei; Yan, Shishen; Liu, Guolei; Han, Guangbing; Yu, Shuyun; Mei, Liangmo; Kang, Shishou

2018-03-01

The spin transparency at the normal/ferromagnetic metal (NM/FM) interface was studied in Pt/YIG/Cu/FM multilayers. The spin current generated by the spin Hall effect (SHE) in Pt flows into Cu/FM due to magnetic insulator YIG blocking charge current and transmitting spin current via the magnon current. Therefore, the nonlocal voltage induced by an inverse spin Hall effect (ISHE) in FM can be detected. With the magnetization of FM parallel or antiparallel to the spin polarization of pure spin currents ({{\\boldsymbol{σ }}}sc}), the spin-independent nonlocal voltage is induced. This indicates that the spin transparency at the Cu/FM interface is spin-independent, which demonstrates that the influence of spin-dependent electrochemical potential due to spin accumulation on the interfacial spin transparency is negligible. Furthermore, a larger spin Hall angle of Fe20Ni80 (Py) than that of Ni is obtained from the nonlocal voltage measurements. Project supported by the National Basic Research Program of China (Grant No. 2015CB921502), the National Natural Science Foundation of China (Grant Nos. 11474184 and 11627805), the 111 Project, China (Grant No. B13029), and the Fundamental Research Funds of Shandong University, China.

Registers of multiple sclerosis in Denmark

DEFF Research Database (Denmark)

Koch-Henriksen, N; Magyari, M; Laursen, B

2015-01-01

between a number of different environmental exposures in the past and the subsequent risk of MS. Some of these studies have been able to exonerate suspected risk factors. The other register, the nationwide Danish Multiple Sclerosis Treatment Register, is a follow-up register for all patients who have......There are two nationwide population-based registers for multiple sclerosis (MS) in Denmark. The oldest register is The Danish Multiple Sclerosis Registry (DMSR), which is an epidemiological register for estimation of prevalence and incidence of MS and survival, and for identifying exposures earlier...... received disease-modifying treatments since 1996. It has, in particular, contributed to the knowledge of the role of antibodies against the biological drugs used for the treatment of MS....

Quantum statistical metastability for a finite spin

Science.gov (United States)

Garanin, D. A.; Chudnovsky, E. M.

2001-01-01

We study quantum-classical escape-rate transitions for uniaxial and biaxial models with finite spins S=10 (such as Mn12Ac and Fe8) and S=100 by a direct numerical approach. At second-order transitions the level making a dominant contribution into thermally assisted tunneling changes gradually with temperature whereas at first-order transitions a group of levels is skipped. For finite spins, the quasiclassical boundaries between first- and second-order transitions are shifted, favoring a second-order transition: For Fe8 in zero field the transition should be first order according to a theory with S-->∞, but we show that there are no skipped levels at the transition. Applying a field along the hard axis in Fe8 makes transition the strongest first order. For the same model with S=100 we confirmed the existence of a region where a second-order transition is followed by a first-order transition [X. Martínes Hidalgo and E. M. Chudnovsky, J. Phys.: Condensed Matter 12, 4243 (2000)].

Giant titanium electron wave function in gallium oxide: A potential electron-nuclear spin system for quantum information processing

Science.gov (United States)

Mentink-Vigier, Frédéric; Binet, Laurent; Vignoles, Gerard; Gourier, Didier; Vezin, Hervé

2010-11-01

The hyperfine interactions of the unpaired electron with eight surrounding G69a and G71a nuclei in Ti-doped β-Ga2O3 were analyzed by electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopies. They are dominated by strong isotropic hyperfine couplings due to a direct Fermi contact interaction with Ga nuclei in octahedral sites of rutile-type chains oriented along b axis, revealing a large anisotropic spatial extension of the electron wave function. Titanium in β-Ga2O3 is thus best described as a diffuse (Ti4+-e-) pair rather than as a localized Ti3+ . Both electron and G69a nuclear spin Rabi oscillations could be observed by pulsed EPR and pulsed ENDOR, respectively. The electron spin decoherence time is about 1μs (at 4 K) and an upper bound of 520μs (at 8 K) is estimated for the nuclear decoherence time. Thus, β-Ga2O3:Ti appears to be a potential spin-bus system for quantum information processing with a large nuclear spin quantum register.

Experimental separation of a frequency spin echo signal

International Nuclear Information System (INIS)

Bun'kov, Yu.M.; Dmitriev, V.V.

1981-01-01

To study systems with bound nuclear-electron precession CsMnF 2 antiferromagnetic light-plane monocrystal was investigated. Crystal orientation was carried out by roentgenoscopy. Measurements were performed at helium temperatures in the 500-700 MHz frequency range. A NMR pulsed spectrometer with generators of both resonance and doubled frequency was used to produce an echo signal (to study by the parametric echo method). It was shown that the theory of the formation of a frequency modulated echo (FM echo) did not fully describe the properties of the echo signals in systems with dynamic frequency shift (DFS). An intense spin echo signal, which formation was apparently connected with other nonlinear properties of the systems with nuclear-electron precession, was observed. The spin echo signal in magnetics with DFS, which properties correspond to notions of the frequency mechanism of echo formation, was experimentally separated. As a result of the investigations it had been possible to settle contradictions between the theory of FM echo formation and the experimental results for the last 9 years. It turned out that the mechanism of FM echo formation in the magnetics with bound nuclear-electron precession was effective only at large delay times between the pulses. In the range of small delays the FM echo is ''jammed'' by a gigantic echo signal of a nature different from that of the traditional FM signal. The constant of gigantic echo intensity drop at increasing delay between the pulses weakly depends on spin-spin relaxation time [ru

Spin-lattice relaxation of individual solid-state spins

Science.gov (United States)

Norambuena, A.; Muñoz, E.; Dinani, H. T.; Jarmola, A.; Maletinsky, P.; Budker, D.; Maze, J. R.

2018-03-01

Understanding the effect of vibrations on the relaxation process of individual spins is crucial for implementing nanosystems for quantum information and quantum metrology applications. In this work, we present a theoretical microscopic model to describe the spin-lattice relaxation of individual electronic spins associated to negatively charged nitrogen-vacancy centers in diamond, although our results can be extended to other spin-boson systems. Starting from a general spin-lattice interaction Hamiltonian, we provide a detailed description and solution of the quantum master equation of an electronic spin-one system coupled to a phononic bath in thermal equilibrium. Special attention is given to the dynamics of one-phonon processes below 1 K where our results agree with recent experimental findings and analytically describe the temperature and magnetic-field scaling. At higher temperatures, linear and second-order terms in the interaction Hamiltonian are considered and the temperature scaling is discussed for acoustic and quasilocalized phonons when appropriate. Our results, in addition to confirming a T5 temperature dependence of the longitudinal relaxation rate at higher temperatures, in agreement with experimental observations, provide a theoretical background for modeling the spin-lattice relaxation at a wide range of temperatures where different temperature scalings might be expected.

Muon spin rotation and other microscopic probes of spin-glass dynamics

International Nuclear Information System (INIS)

MacLaughlin, D.E.

1980-01-01

A number of different microscopic probe techniques have been employed to investigate the onset of the spin-glass state in dilute magnetic alloys. Among these are Moessbauer-effect spectroscopy, neutron scattering, ESR of the impurity spins, host NMR and, most recently, muon spin rotation and depolarization. Spin probes yield information on the microscopic static and dynamic behavior of the impurity spins, and give insight into both the spin freezing process and the nature of low-lying excitations in the ordered state. Microscopic probe experiments in spin glasses are surveyed, and the unique advantages of muon studies are emphasized

Quantifying Spin Hall Angles from Spin Pumping : Experiments and Theory

NARCIS (Netherlands)

Mosendz, O.; Pearson, J.E.; Fradin, F.Y.; Bauer, G.E.W.; Bader, S.D.; Hoffmann, A.

2010-01-01

Spin Hall effects intermix spin and charge currents even in nonmagnetic materials and, therefore, ultimately may allow the use of spin transport without the need for ferromagnets. We show how spin Hall effects can be quantified by integrating Ni80Fe20|normal metal (N) bilayers into a coplanar

The Danish Pathology Register

DEFF Research Database (Denmark)

Bjerregaard, Beth; Larsen, Ole B

2011-01-01

The National Board of Health, Denmark in 1997 published guidelines for reporting of pathology data and the Danish Pathology Register (DPR) was established.......The National Board of Health, Denmark in 1997 published guidelines for reporting of pathology data and the Danish Pathology Register (DPR) was established....

Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure

KAUST Repository

Wang, Xuhui; Ortiz Pauyac, Christian; Manchon, Aurelien

2014-01-01

Ferromagnetic heterostructures provide an ideal platform to explore the nature of spin-orbit torques arising from the interplay mediated by itinerant electrons between a Rashba-type spin-orbit coupling and a ferromagnetic exchange interaction. For such a prototypic system, we develop a set of coupled diffusion equations to describe the diffusive spin dynamics and spin-orbit torques. We characterize the spin torque and its two prominent—out-of-plane and in-plane—components for a wide range of relative strength between the Rashba coupling and ferromagnetic exchange. The symmetry and angular dependence of the spin torque emerging from our simple Rashba model is in an agreement with experiments. The spin diffusion equation can be generalized to incorporate dynamic effects such as spin pumping and magnetic damping.

Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure

KAUST Repository

Wang, Xuhui

2014-02-07

Ferromagnetic heterostructures provide an ideal platform to explore the nature of spin-orbit torques arising from the interplay mediated by itinerant electrons between a Rashba-type spin-orbit coupling and a ferromagnetic exchange interaction. For such a prototypic system, we develop a set of coupled diffusion equations to describe the diffusive spin dynamics and spin-orbit torques. We characterize the spin torque and its two prominent—out-of-plane and in-plane—components for a wide range of relative strength between the Rashba coupling and ferromagnetic exchange. The symmetry and angular dependence of the spin torque emerging from our simple Rashba model is in an agreement with experiments. The spin diffusion equation can be generalized to incorporate dynamic effects such as spin pumping and magnetic damping.

Electron-Spin Filters Would Offer Spin Polarization Greater than 1

Science.gov (United States)

Ting, David Z.

2009-01-01

A proposal has been made to develop devices that would generate spin-polarized electron currents characterized by polarization ratios having magnitudes in excess of 1. Heretofore, such devices (denoted, variously, as spin injectors, spin polarizers, and spin filters) have typically offered polarization ratios having magnitudes in the approximate range of 0.01 to 0.1. The proposed devices could be useful as efficient sources of spin-polarized electron currents for research on spintronics and development of practical spintronic devices.

Efficient micromagnetic modelling of spin-transfer torque and spin-orbit torque

Science.gov (United States)

Abert, Claas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter

2018-05-01

While the spin-diffusion model is considered one of the most complete and accurate tools for the description of spin transport and spin torque, its solution in the context of dynamical micromagnetic simulations is numerically expensive. We propose a procedure to retrieve the free parameters of a simple macro-spin like spin-torque model through the spin-diffusion model. In case of spin-transfer torque the simplified model complies with the model of Slonczewski. A similar model can be established for the description of spin-orbit torque. In both cases the spin-diffusion model enables the retrieval of free model parameters from the geometry and the material parameters of the system. Since these parameters usually have to be determined phenomenologically through experiments, the proposed method combines the strength of the diffusion model to resolve material parameters and geometry with the high performance of simple torque models.

Spin Drag and Spin-Charge Separation in Cold Fermi Gases

International Nuclear Information System (INIS)

Polini, Marco; Vignale, Giovanni

2007-01-01

Low-energy spin and charge excitations of one-dimensional interacting fermions are completely decoupled and propagate with different velocities. These modes, however, can decay due to several possible mechanisms. In this Letter we expose a new facet of spin-charge separation: not only the speeds but also the damping rates of spin and charge excitations are different. While the propagation of long-wavelength charge excitations is essentially ballistic, spin propagation is intrinsically damped and diffusive. We suggest that cold Fermi gases trapped inside a tight atomic waveguide offer the opportunity to measure the spin-drag relaxation rate that controls the broadening of a spin packet

IT Risk register

OpenAIRE

Kohout, Karel

2011-01-01

The theoretical part of the thesis analyzes several selected methodologies and best-practices related to information technology risks management, with focus on documents and guidance developed by ISACA. It builds a set of ideas and basic requirements for effective model of an IT risk register. Strong emphasis is placed on mapping CobiT 4.1 based Risk IT to COBIT 5. The practical part describes implementation of an exploratory web-based IT risk register in Python programming language utilizing...

[THE INFLUENCE OF SHIFT WORK ON WORKER'S HEALTH STATUS (REVIEW)].

Science.gov (United States)

Chernikova, E F

2015-01-01

The article provides an overview of domestic and foreign works on the impact of the replaceable labor on the efficiency, general state of health, the health and the dream of workers. Many hours shifts and overtime work were found to disturb likely familiar rhythms (sleep, wakefulness, performance), change the metabolic and hormonal metabolisms, reducing the recovery period between duties, contribute to more rapid development of fatigue. The consequence of circadian dyschrony may be the development of diseases of the cardiovascular system and cancer incidence. Studies have shown that sleep disorders are associated with metabolic changes, and particularly, obesity. In persons working in shifts, there are more often registered as individual features of the metabolic syndrome and the whole syndrome. It is noted that persons forming this group are at higher risk of developing diseases of the gastrointestinal tract. Thus, the problem of shift work is presented to be very important. Knowledge of ways and mechanisms that explain the impact of shift work on health is necessary to evaluate the professional risk. In the system of health measures the attention should be given to the rationalization of work and rest regimens, prevention of fatigue, struggle with sleep disorders and obesity.

Spinning Them Off: Entrepreneuring Practices in Corporate Spin-Offs

Directory of Open Access Journals (Sweden)

Katja Maria Hydle

2016-01-01

Full Text Available This paper focuses on the practices between parent and child firms in corporate spinoffs. We uncover the enacted aspects of knowledge, called knowing, through theories from seven cases of incumbent-backed spin-offs and find that the management of the parent firms are highly involved in the spin-offs. The practices associated with spinning off are solving problems, involving multidisciplinary expertise and entrepreneuring management at the parent firm. We contribute to the spin-off literature by discussing the knowledge required for successfully spinning off child firms and to practice theory by empirically uncovering the practical understanding involved in the origin and perpetuation of an organization.

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

Spin and tunneling dynamics in an asymmetrical double quantum dot with spin-orbit coupling: Selective spin transport device

Science.gov (United States)

Singh, Madhav K.; Jha, Pradeep K.; Bhattacherjee, Aranya B.

2017-09-01

In this article, we study the spin and tunneling dynamics as a function of magnetic field in a one-dimensional GaAs double quantum dot with both the Dresselhaus and Rashba spin-orbit coupling. In particular, we consider different spatial widths for the spin-up and spin-down electronic states. We find that the spin dynamics is a superposition of slow as well as fast Rabi oscillations. It is found that the Rashba interaction strength as well as the external magnetic field strongly modifies the slow Rabi oscillations which is particularly useful for implementing solid state selective spin transport device.

Structure of the spin polarization spectrum of secondary electrons emitted from nickel

International Nuclear Information System (INIS)

Helman, J.S.

1985-01-01

The main features of the structure observed in the energy resolved spin polarization of secondary electrons emitted from Ni are interpreted in terms of surface and bulk plasmon assisted emission. The model also predicts a measureable shift of the main polarization peak of about 0.3 eV to lower energies as the temperature is raised from room temperature to closely below the Curie temperature. (Author) [pt

Enhanced Spin-Orbit Torque via Modulation of Spin Current Absorption

KAUST Repository

Qiu, Xuepeng

2016-11-18

The magnitude of spin-orbit torque (SOT), exerted to a ferromagnet (FM) from an adjacent heavy metal (HM), strongly depends on the amount of spin current absorbed in the FM. We exploit the large spin absorption at the Ru interface to manipulate the SOTs in HM/FM/Ru multilayers. While the FM thickness is smaller than its spin dephasing length of 1.2 nm, the top Ru layer largely boosts the absorption of spin currents into the FM layer and substantially enhances the strength of SOT acting on the FM. Spin-pumping experiments induced by ferromagnetic resonance support our conclusions that the observed increase in the SOT efficiency can be attributed to an enhancement of the spin-current absorption. A theoretical model that considers both reflected and transmitted mixing conductances at the two interfaces of FM is developed to explain the results.

Excitation of coherent propagating spin waves by pure spin currents.

Science.gov (United States)

Demidov, Vladislav E; Urazhdin, Sergei; Liu, Ronghua; Divinskiy, Boris; Telegin, Andrey; Demokritov, Sergej O

2016-01-28

Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

International Nuclear Information System (INIS)

Miah, M Idrish

2008-01-01

We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs

Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Miah, M Idrish [Nanoscale Science and Technology Centre and School of 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

2008-09-21

We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs.

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.

Current-induced spin polarization in a spin-polarized two-dimensional electron gas with spin-orbit coupling

International Nuclear Information System (INIS)

Wang, C.M.; Pang, M.Q.; Liu, S.Y.; Lei, X.L.

2010-01-01

The current-induced spin polarization (CISP) is investigated in a combined Rashba-Dresselhaus spin-orbit-coupled two-dimensional electron gas, subjected to a homogeneous out-of-plane magnetization. It is found that, in addition to the usual collision-related in-plane parts of CISP, there are two impurity-density-free contributions, arising from intrinsic and disorder-mediated mechanisms. The intrinsic parts of spin polarization are related to the Berry curvature, analogous with the anomalous and spin Hall effects. For short-range collision, the disorder-mediated spin polarizations completely cancel the intrinsic ones and the total in-plane components of CISP equal those for systems without magnetization. However, for remote disorders, this cancellation does not occur and the total in-plane components of CISP strongly depend on the spin-orbit interaction coefficients and magnetization for both pure Rashba and combined Rashba-Dresselhaus models.

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

Science.gov (United States)

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

2005-11-01

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

Very wide register : an asymmetric register file organization for low power embedded processors.

NARCIS (Netherlands)

Raghavan, P.; Lambrechts, A.; Jayapala, M.; Catthoor, F.; Verkest, D.T.M.L.; Corporaal, H.

2007-01-01

In current embedded systems processors, multi-ported register files are one of the most power hungry parts of the processor, even when they are clustered. This paper presents a novel register file architecture, which has single ported cells and asymmetric interfaces to the memory and to the

Spin-resolved electron waiting times in a quantum-dot spin valve

Science.gov (United States)

Tang, Gaomin; Xu, Fuming; Mi, Shuo; Wang, Jian

2018-04-01

We study the electronic waiting-time distributions (WTDs) in a noninteracting quantum-dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using the scattering matrix approach. Since the quantum-dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD, and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin-transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first-passage time distributions to quantitatively characterize the spin-flip process. We observe that influence degree versus spin-transfer torque for different noncollinear angles as well as different polarizations collapse into a single curve showing universal behaviors. This demonstrates that cross-channel WTDs can be a pathway to characterize spin correlation in spintronics system.

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

Spin transport in spin filtering magnetic tunneling junctions.

Science.gov (United States)

Li, Yun; Lee, Eok Kyun

2007-11-01

Taking into account spin-orbit coupling and s-d interaction, we investigate spin transport properties of the magnetic tunneling junctions with spin filtering barrier using Landauer-Büttiker formalism implemented with the recursive algorithm to calculate the real-space Green function. We predict completely different bias dependence of negative tunnel magnetoresistance (TMR) between the systems composed of nonmagnetic electrode (NM)/ferromagnetic barrier (FB)/ferromagnet (FM) and NM/FB/FM/NM spin filtering tunnel junctions (SFTJs). Analyses of the results provide us possible ways of designing the systems which modulate the TMR in the negative magnetoresistance regime.

Entangling two transportable neutral atoms via local spin exchange.

Science.gov (United States)

Kaufman, A M; Lester, B J; Foss-Feig, M; Wall, M L; Rey, A M; Regal, C A

2015-11-12

To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.