Charge reversal Fourier transform ion cyclotron resonance mass spectrometry.
Lobodin, Vladislav V; Savory, Joshua J; Kaiser, Nathan K; Dunk, Paul W; Marshall, Alan G
2013-02-01
We report the first charge reversal experiments performed by tandem-in-time rather than tandem-in-space MS/MS. Precursor odd-electron anions from fullerene C(60), and even-electron ions from 2,7-di-tert-butylfluorene-9-carboxylic acid and 3,3'-bicarbazole were converted into positive product ions ((-)CR(+)) inside the magnet of a Fourier transform ion cyclotron resonance mass spectrometer. Charge reversal was activated by irradiating precursor ions with high energy electrons or UV photons: the first reported use of those activation methods for charge reversal. We suggest that high energy electrons achieve charge reversal in one step as double electron transfer, whereas UV-activated (-)CR(+) takes place stepwise through two single electron transfers and formally corresponds to a neutralization-reionization ((-)NR(+)) experiment.
The Sound of Dark Matter: Searching for Light Scalars with Resonant-Mass Detectors
Arvanitaki, Asimina; Van Tilburg, Ken
2016-01-01
The fine structure constant and the electron mass in string theory are determined by the values of scalar fields called moduli. If the dark matter takes on the form of such a light modulus, it oscillates with a frequency equal to its mass and an amplitude determined by the local dark matter density. This translates into an oscillation of the size of a solid that can be observed by resonant-mass antennae. Existing and proposed resonant-mass detectors can probe dark matter moduli with frequencies between 1 kHz and 1 GHz, with much better sensitivity than force measurements.
Sound of Dark Matter: Searching for Light Scalars with Resonant-Mass Detectors
Arvanitaki, Asimina; Dimopoulos, Savas; Van Tilburg, Ken
2016-01-01
The fine-structure constant and the electron mass in string theory are determined by the values of scalar fields called moduli. If the dark matter takes on the form of such a light modulus, it oscillates with a frequency equal to its mass and an amplitude determined by the local dark-matter density. This translates into an oscillation of the size of a solid that can be observed by resonant-mass antennas. Existing and planned experiments, combined with a dedicated resonant-mass detector proposed in this Letter, can probe dark-matter moduli with frequencies between 1 kHz and 1 GHz, with much better sensitivity than searches for fifth forces.
Sound of Dark Matter: Searching for Light Scalars with Resonant-Mass Detectors.
Arvanitaki, Asimina; Dimopoulos, Savas; Van Tilburg, Ken
2016-01-22
The fine-structure constant and the electron mass in string theory are determined by the values of scalar fields called moduli. If the dark matter takes on the form of such a light modulus, it oscillates with a frequency equal to its mass and an amplitude determined by the local dark-matter density. This translates into an oscillation of the size of a solid that can be observed by resonant-mass antennas. Existing and planned experiments, combined with a dedicated resonant-mass detector proposed in this Letter, can probe dark-matter moduli with frequencies between 1 kHz and 1 GHz, with much better sensitivity than searches for fifth forces.
H∞ Loop shaping control for PLL-based mechanical resonance tracking in NEMS resonant mass sensors
Kharrat, Chady; Colinet, Eric; Voda, Alina
2008-01-01
International audience; Abstract--A simple dynamic detection of the resonance frequency shift in NEMS resonant mass sensors is described. This is done without the use of an external frequency sweep signal nor a frequency counter limiting the dynamic variation detection. Neither an amplitude control nor a phase switcher is required for maintaining the resonant oscillations. The sensor is driven directly by the VCO's output for which the control signal is calculated by a robust H∞ controller us...
Past, present and future of the Resonant-Mass gravitational wave detectors
Institute of Scientific and Technical Information of China (English)
Odylio Denys Aguiar
2011-01-01
Resonant-mass gravitational wave detectors are reviewed from the concept of gravitational waves and its mathematical derivation, using Einstein's general relativity, to the present status of bars and spherical detectors, and their prospects for the future, which include dual detectors and spheres with non-resonant transducers. The review not only covers technical aspects of detectors and sciences that will be done,but also analyzes the subject in a historical perspective, covering the various detection efforts over four decades, starting from Weber's pioneering work.
Fourier Transfrom Ion Cyclotron Resonance Mass Spectrometry at High Magnetic Field
Marshall, Alan G.
1998-03-01
At high magnetic field (9.4 tesla at NHMFL), Fourier transform ion cyclotron resonance mass spectrometry performance improves dramatically: mass resolving power, axialization efficiency, and scan speed (each proportional to B), maximum ion mass, dynamic range, ion trapping period, kinetic energy, and electron self-cooling rate for sympathetic cooling (each proportional to B^2), and ion coalescence tendency (proportional 1/B^2). These advantages may apply singly (e.g., unit mass resolution for proteins of >100,000 Da), or compound (e.g., 10-fold improvement in S/N ratio for 9.4 T vs. 6 T at the same resolving power). Examples range from direct determination of molecular formulas of diesel fuel components by accurate mass measurement (=B10.1 ppm) to protein structure and dynamics probed by H/D exchange. This work was supported by N.S.F. (CHE-93-22824; CHE-94-13008), N.I.H. (GM-31683), Florida State University, and the National High Magnetic Field Laboratory in Tallahassee, FL.
Mead, R. N.; Podgorski, D. C.; Mullaugh, K. M.; Avery, B.; Kieber, R. J.; Willey, J. D.; Cooper, W. T.
2011-12-01
Rainwater is a complex, heterogeneous mixture of dissolved organic matter (DOM) that remains largely uncharacterized at the molecular level. Rainwater with dissolved organic carbon values ranging from 3 to 450 μM was collected during 40 separate rain events from 2007-2011 that included coastal and terrestrial storms based upon 36 hour back trajectories. Individual rain samples were lypholized and solvent added in preparation for analysis by negative electrospray ionization and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This data set is unique in that each rain event was analyzed individually and not combined allowing for unprecedented insight into rainwater DOM at the molecular level on an episodic basis. Unique elemental compositions were assigned for compounds belonging to CHO, CHOS and CHON classes. Data visualization by van Krevelen diagrams showed clear differences in coastal and terrestrial storm events with a majority of coastal storms having high H/C (1.5-2.0) relative to terrestrial storms. Further inspection of the data revealed that rainwater has relatively high O/C (1.4) and low H/C (<0.5) which suggests rainwater DOM is compositionally different than fog water, water soluble organic carbon isolated from aerosols and surface waters.
Hourani, Nadim
2013-10-01
Rationale Polycyclic aromatic sulfur heterocycles (PASHs) are detrimental species for refining processes in petroleum industry. Current mass spectrometric Methods that determine their composition are often preceded by derivatization and dopant addition approaches. Different ionization Methods have different impact on the molecular assignment of complex PASHs. The analysis of such species under atmospheric pressure chemical ionization (APCI) is still considered limited due to uncontrolled ion generation with low- and high-mass PASHs. Methods The ionization behavior of a model mixture of five selected PASH standards was investigated using an APCI source with nitrogen as the reagent gas. A complex thiophenic fraction was separated from a vacuum gas oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same ionization pattern was observed for the real thiophenic sample. It was found that S1 class species were the major sulfur-containing species found in the VGO sample. These species indicated the presence of alkylated benzothiophenic (BT), dibenzothiophenic (DBT) and benzonaphthothiophenic (BNT) series that were detected by APCI-FTICR MS. CONCLUSIONS This study provides an established APCI-FTICR MS method for the analysis of complex PASHs. PASHs were detected without using any derivatization and without fragmentation. The method can be used for the analysis of S-containing crude oil samples. © 2013 John Wiley & Sons, Ltd.
Multilayer graphene electrodes for one-port surface acoustic wave resonator mass sensor
Leong, Ainan; Swamy, Varghese; Ramakrishnan, N.
2017-02-01
A one-port surface acoustic wave (SAW) resonator mass sensor composed of multilayer graphene (MLG) electrodes was investigated by the finite element method (FEM) and analyses were carried out to study the enhancement of sensitivity and the secondary effects caused by MLG electrodes on the performance of the resonator. Unlike metal electrodes, MLG electrode offers elastic loading to the contact surface, as evidenced by the increase in the surface velocity of the SAW device. In terms of the sensitivity of the mass sensor, MLG electrode showed the largest center frequency shift in response to a change in mass loading, as well as when used as a gas sensor to detect volatile organic compounds (VOCs). Also, MLG electrodes offered the least triple transit signal (TTS) and bulk acoustic wave (BAW) generations compared with Al and Au–Cr electrodes. Thus, the one-port SAW resonator with graphene electrodes not only possesses excellent performance characteristics but also gives rise to new opportunities in the development of highly sensitive mass sensors.
Shaw, Jared B.; Lin, Tzu-Yung; Leach, Franklin E.; Tolmachev, Aleksey V.; Tolić, Nikola; Robinson, Errol W.; Koppenaal, David W.; Paša-Tolić, Ljiljana
2016-12-01
We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged Substance P with minimal spectral averaging, and 8158 molecular formulas assigned to Suwannee River Fulvic Acid standard with root-mean-square (RMS) error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apo-transferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g., 6 s time-domains with absorption mode processing yielded resolution of approximately 1 M at m/z = 2700).
Fourier Transform Ion Cyclotron Resonance Mass Spectrometry at the Cyclotron Frequency
Nagornov, Konstantin O.; Kozhinov, Anton N.; Tsybin, Yury O.
2017-02-01
The phenomenon of ion cyclotron resonance allows for determining mass-to-charge ratio, m/z, of an ensemble of ions by means of measurements of their cyclotron frequency, ω c . In Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), the ω c quantity is usually unavailable for direct measurements: the resonant state is located close to the reduced cyclotron frequency (ω+), whereas the ω c and the corresponding m/z values may be calculated via theoretical derivation from an experimental estimate of the ω+ quantity. Here, we describe an experimental observation of a new resonant state, which is located close to the ω c frequency and is established because of azimuthally-dependent trapping electric fields of the recently developed ICR cells with narrow aperture detection electrodes. We show that in mass spectra, peaks close to ω+ frequencies can be reduced to negligible levels relative to peaks close to ω c frequencies. Due to reduced errors with which the ω c quantity is obtained, the new resonance provides a means of cyclotron frequency measurements with precision greater than that achieved when ω+ frequency peaks are employed. The described phenomenon may be considered for a development into an FT-ICR MS technology with increased mass accuracy for applications in basic research, life, and environmental sciences.
Energy Technology Data Exchange (ETDEWEB)
Shaw, Jared B.; Lin, Tzu-Yung; Leach, Franklin E.; Tolmachev, Aleksey V.; Tolić, Nikola; Robinson, Errol W.; Koppenaal, David W.; Paša-Tolić, Ljiljana
2016-10-12
We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged substance P with minimal spectral averaging, and 8,158 molecular formulas assigned to Suwannee River Fulvic Acid standard with RMS error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apotransferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g. 6 s time-domains with absorption mode processing yielded resolution of approximately 1M at m/z =2,700).
Fourier Transform Ion Cyclotron Resonance Mass Spectrometry at the Cyclotron Frequency.
Nagornov, Konstantin O; Kozhinov, Anton N; Tsybin, Yury O
2017-04-01
The phenomenon of ion cyclotron resonance allows for determining mass-to-charge ratio, m/z, of an ensemble of ions by means of measurements of their cyclotron frequency, ω c . In Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), the ω c quantity is usually unavailable for direct measurements: the resonant state is located close to the reduced cyclotron frequency (ω+), whereas the ω c and the corresponding m/z values may be calculated via theoretical derivation from an experimental estimate of the ω+ quantity. Here, we describe an experimental observation of a new resonant state, which is located close to the ω c frequency and is established because of azimuthally-dependent trapping electric fields of the recently developed ICR cells with narrow aperture detection electrodes. We show that in mass spectra, peaks close to ω+ frequencies can be reduced to negligible levels relative to peaks close to ω c frequencies. Due to reduced errors with which the ω c quantity is obtained, the new resonance provides a means of cyclotron frequency measurements with precision greater than that achieved when ω+ frequency peaks are employed. The described phenomenon may be considered for a development into an FT-ICR MS technology with increased mass accuracy for applications in basic research, life, and environmental sciences. Graphical Abstract ᅟ.
Pollier, Jacob; Morreel, Kris; Geelen, Danny; Goossens, Alain
2011-01-01
Triterpenes are one of the largest classes of plant natural products, with an enormous variety in structure and bioactivities. Here, triterpene saponins from hairy roots of the model legume Medicago truncatula were profiled with reversed-phase liquid chromatography coupled to negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (LC ESI FT-ICR MS). Owing to the accuracy of the FT-ICR MS, reliable molecular formulas of the detected compounds could be ...
Energy Technology Data Exchange (ETDEWEB)
Maruyama, Sho [Fermilab
2015-12-15
The invariant mass of tau lepton pairs turns out to be smaller than the resonant mass of their mother particle and the invariant mass distribution is stretched wider than the width of the resonant mass as significant fraction of tau lepton momenta are carried away by neutrinos escaping undetected at collider experiments. This paper describes a new approach to reconstruct resonant masses of heavy particles decaying to tau leptons at such experiments. A typical example is a Z or Higgs boson decaying to a tau pair. Although the new technique can be used for each tau lepton separately, I combine two tau leptons to improve mass resolution by requiring the two tau leptons are lined up in a transverse plane. The method is simple to implement and complementary to the collinear approximation technique that works well when tau leptons are not lined up in a transverse plane. The reconstructed mass can be used as another variable in analyses that already use a visible tau pair mass and missing transverse momentum as these variables are not explicitly used in the stochastic mass-reconstruction to select signal-like events.
Maruyama, Sho
2015-01-01
The invariant mass of tau lepton pairs turns out to be smaller than the resonant mass of their mother particle and the invariant mass distribution is stretched wider than the width of the resonant mass as significant fraction of tau lepton momenta are carried away by neutrinos escaping undetected at collider experiments. This paper describes a new approach to reconstruct resonant masses of heavy particles decaying to tau leptons at such experiments. A typical example is a Z or Higgs boson decaying to a tau pair. Although the new technique can be used for each tau lepton separately, I combine two tau leptons to improve mass resolution by requiring the two tau leptons are lined up in a transverse plane. The method is simple to implement and complementary to the collinear approximation technique that works well when tau leptons are not lined up in a transverse plane. The reconstructed mass can be used as another variable in analyses that already use a visible tau pair mass and missing transverse momentum as thes...
Melucci, Dora; Bendini, Alessandra; Tesini, Federica; Barbieri, Sara; Zappi, Alessandro; Vichi, Stefania; Conte, Lanfranco; Gallina Toschi, Tullia
2016-08-01
At present, the geographical origin of extra virgin olive oils can be ensured by documented traceability, although chemical analysis may add information that is useful for possible confirmation. This preliminary study investigated the effectiveness of flash gas chromatography electronic nose and multivariate data analysis to perform rapid screening of commercial extra virgin olive oils characterized by a different geographical origin declared in the label. A comparison with solid phase micro extraction coupled to gas chromatography mass spectrometry was also performed. The new method is suitable to verify the geographic origin of extra virgin olive oils based on principal components analysis and discriminant analysis applied to the volatile profile of the headspace as a fingerprint. The selected variables were suitable in discriminating between "100% Italian" and "non-100% Italian" oils. Partial least squares discriminant analysis also allowed prediction of the degree of membership of unknown samples to the classes examined.
Clemen, Martin; Gernert, Claus; Peters, Jonathan; Grotemeyer, Jürgen
2013-01-01
The fragmentation reactions of Rhodamine B have been investigated by the use of electrospray ionization mass spectra in a high mass resolving ion cyclotron resonance mass spectrometer. Using high resolution, it could be shown that the loss of 44 mass units from the molecular ion is due to propane; the measured masses were inconsistent with loss of carbon dioxide. These conclusions are supported using deuterium-labeled Rhodamine B. This sample again only shows the loss of fully-deuterated propane verifying the high-resolution data. These findings illustrate very clearly that the conclusions based solely on low resolution spectra were false. The general implication on fragmentations of aromatic acids is discussed.
The nucleon and Delta-resonance masses in relativistic chiral effective-field theory
Energy Technology Data Exchange (ETDEWEB)
V. Pascalutsa; M. Vanderhaeghen
2005-11-28
We study the chiral behavior of the nucleon and De-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the {pi} N and {pi}{Delta} one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the {pi} N-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and De masses, while inclusion of the {pi}/De loops tends to spoil this agreement.
Marto, J A; White, F M; Seldomridge, S; Marshall, A G
1995-11-01
Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode.
Hnybida, Jeff
2016-10-01
We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. In doing so the sums over spins have been carried out. The boundary data of each n-valent node is explicitly reduced with respect to the local gauge invariance and has a manifest geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.
Pollier, Jacob; Morreel, Kris; Geelen, Danny; Goossens, Alain
2011-06-24
Triterpenes are one of the largest classes of plant natural products, with an enormous variety in structure and bioactivities. Here, triterpene saponins from hairy roots of the model legume Medicago truncatula were profiled with reversed-phase liquid chromatography coupled to negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (LC ESI FT-ICR MS). Owing to the accuracy of the FT-ICR MS, reliable molecular formulas of the detected compounds could be predicted, which, together with the generated MS(n) spectra, allowed the tentative identification of 79 different saponins, of which 61 had not been detected previously in M. truncatula. Upon collision-induced dissociation of saponins that contain a uronic acid residue in the sugar chain, fragment ions resulting from cross-ring cleavages of the uronic acid residues were observed. The identified saponins are glycosides of 10 different sapogenins, of which three were not detected before in M. truncatula. Zanhic acid glycosides, which are prevalent in the aerial parts of M. truncatula, were absent in the hairy root extracts. This metabolite compendium will facilitate future functional genomic studies of triterpene saponin biosynthesis in M. truncatula.
Wu, Zhigang; Rodgers, Ryan P; Marshall, Alan G
2004-08-25
Adulteration of vegetable oil is of concern for both commercial and health reasons. Compositional based fingerprints can potentially reveal both the oil source and its possible adulteration. Here, electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) resolves and identifies literally thousands of distinct chemical components of commercial canola, olive, and soybean oils, without extraction or other wet chemical separation pretreatment. In negative-ion ESI FT-ICR MS, the acidic components of soybean oil are easily distinguished from those of canola and olive oil based on relative abundances of C(18) fatty acids, whereas olive oil differs from canola and soybean oil based on relative abundances of tocopherols. In positive-ion ESI FT-ICR MS, the three oils are readily distinguished according to the relative abundances of di- and triacylglycerols with various numbers of double bonds in the fatty acid chains. We demonstrate the detection of soybean oil as an adulterant of olive oil, based on relative abundances of members of each of several chemical families. We suggest that the detailed chemical compositions of vegetable oils can be used to characterize them and to detect and identify adulterants.
Hegazi, Abdelrahman H; Fathalla, Eiman M; Andersson, Jan T
2014-09-01
Different weathering factors act to change petroleum composition once it is spilled into the environment. n-Alkanes, biomarkers, low-molecular weight polyaromatic hydrocarbons and sulfur heterocycles compositional changing in the environment have been extensively studied by different researchers and many parameters have been used for oil source identification and monitoring of weathering and biological degradation processes. In this work, we studied the fate of medium-molecular weight polycyclic aromatic disulfur heterocycles (PAS2Hs), up to ca. 900Da, of artificially weathered Flotta North Sea crude oil by ultra high-resolution Fourier transform ion cyclotron resonance mass spectrometry. It was found that PAS2Hs in studied crude oil having double bond equivalents (DBE) from 5 to 8 with a mass range from ca 316 to 582Da were less influenced even after six months artificial weathering experiment. However, compounds having DBEs 12, 11 and 10 were depleted after two, four and six months weathering, respectively. In addition, DBE 9 series was more susceptible to weathering than those of DBE 7 and 8.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The mass spectra of five peptides with biological activities are reported. All mass spectra were recorded using a 4.7-T Fourier transform ion cyclotron resonance mass spectrometer equipped with an external electrospray source. The accurate molecular weights for the five peptides prepared by solid phase synthesis were measured as 1765.9013, 1063.5420, 1092.5254, 820.3804 and 1078.5193, respectively. All the data were obtained with the external calibration. Differences between observed and theoretical monoisotopic molecular weights were in the (0.2-1.0)×10-6 range. The complete primary sequence for the five polypep-tides were determined using the method of in-source electro-spray ionization/collision induced dissociation (ESI/CID). All the intact y series ions and b series ions were obtained from various peptides respectively, thus determining the sequences of the five polypeptides. We found that the measured accura-te molecular mass of sample 4 was not in agreement with that expected from the planned synthetic peptide. The se-quences of sample 4 were determined through analysis. The corresponding accurate masses of b series ions and y series ions were gained, which proved that it was correct to re-determine the sequences.
Energy Technology Data Exchange (ETDEWEB)
Yan, Jing; Zhou, Mowei; Gilbert, Joshua D.; Wolff, Jeremy J.; Somogyi, Árpád; Pedder, Randall E.; Quintyn, Royston S.; Morrison, Lindsay J.; Easterling, Michael L.; Paša-Tolić, Ljiljana; Wysocki, Vicki H.
2017-01-03
Mass spectrometry continues to develop as a valuable tool in the analysis of proteins and protein complexes. In protein complex mass spectrometry studies, surface-induced dissociation (SID) has been successfully applied in quadrupole time-of-flight (Q-TOF) instruments. SID provides structural information on non-covalent protein complexes that is complementary to other techniques. However, the mass resolution of Q-TOF instruments can limit the information that can be obtained for protein complexes by SID. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides ultrahigh resolution and ultrahigh mass accuracy measurements. In this study, an SID device was designed and successfully installed in a hybrid FT-ICR instrument in place of the standard gas collision cell. The SID-FT-ICR platform has been tested with several protein complex systems (homooligomers, a heterooligomer, and a protein-ligand complex, ranging from 53 kDa to 85 kDa), and the results are consistent with data previously acquired on Q-TOF platforms, matching predictions from known protein interface information. SID fragments with the same m/z but different charge states are well-resolved based on distinct spacing between adjacent isotope peaks, and the addition of metal cations and ligands can also be isotopically resolved with the ultrahigh mass resolution available in FT-ICR.
Hnybida, Jeff
2015-01-01
We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. Thus the sums over spins have been carried out. We focus on the character expansion of Yang-Mills theory which is an approximate heat kernel regularization of BF theory. The boundary data of each $n$-valent node is an element of the Grassmannian Gr(2,$n$) which carries a coherent representation of U($n$) and a geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.
Suzuki, Hideyuki; Sasaki, Ryosuke; Ogata, Yoshiyuki; Nakamura, Yukiko; Sakurai, Nozomu; Kitajima, Mariko; Takayama, Hiromitsu; Kanaya, Shigehiko; Aoki, Koh; Shibata, Daisuke; Saito, Kazuki
2008-01-01
Flavonoids detected from a model legume plant, Lotus japonicus accessions Miyakojima MG-20 and Gifu B-129, were profiled using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR/MS). Five flavonols and two anthocyanidins were detected as aglycones. LC-FTICR/MS facilitated simultaneous detection of 61 flavonoids including compounds that have not been reported previously. Chemical information of the peaks such as retention time, lambdamax, m/z value of the quasi-molecular ion, m/z value of MS/MS fragment ions, and relative intensity of MS/MS fragments was obtained, along with the molecular formulas and conjugate structures. Fourteen were completely identified by comparison with authentic compounds. The high accuracy of m/z values, being 0.081 ppm between observed and theoretical values, allowed prediction of molecular formulas of unknown compounds with the help of isotope peak information for determination of chemical composition. Based on a predicted elemental composition, the presence of a novel nitrogen-containing flavonoid was proposed. A comparison of flavonoid profiles in flowers, stems, and leaves demonstrated that the flowers yielded the most complex profile, containing 30 flower-specific flavonoids including gossypetin glycosides and isorhamnetin glycosides. A comparison of flavonoid profiles between MG-20 and B-129 grown under the same conditions revealed that the accumulation of anthocyanins was higher in B-129 than MG-20, particularly in the stem. Developmental changes in the flavonoid profiles demonstrated that kaempferol glycosides increased promptly after germination. In contrast, quercetin glycosides, predominant flavonoids in the seeds, were not detectable in growing leaves.
Chikushi, Hiroaki; Fujii, Yuka; Toda, Kei
2012-09-21
In this work, a method for measuring polychlorinated biphenyls (PCBs) in contaminated solid waste was investigated. This waste includes paper that is used in electric transformers to insulate electric components. The PCBs in paper sample were extracted by supercritical fluid extraction and analyzed by gas chromatography-electron capture detection. The recoveries with this method (84-101%) were much higher than those with conventional water extraction (0.08-14%), and were comparable to those with conventional organic solvent extraction. Limit of detection was 0.0074 mg kg(-1) and measurable up to 2.5 mg kg(-1) for 0.5 g of paper sample. Data for real insulation paper by the proposed method agreed well with those by the conventional organic solvent extraction. Extraction from wood and concrete was also investigated and good performance was obtained as well as for paper samples. The supercritical fluid extraction is simpler, faster, and greener than conventional organic solvent extraction.
Energy Technology Data Exchange (ETDEWEB)
Cao, Dong [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Haidian District, Beijing 100085 (China); Huang, Huogao [Department of Endocrinology and Rheumatology, Navy General Hospital, PLA, 6 Fucheng Road, Haidian District, Beijing 100048 (China); Hu, Ming [Central Lab Navy General Hospital, PLA, 6 Fucheng Road, Haidian District, Beijing 100048 (China); Cui, Lin; Geng, Fanglan; Rao, Ziyu; Niu, Hongyun; Cai, Yaqi [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Haidian District, Beijing 100085 (China); Kang, Yuehui, E-mail: yhkang@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Haidian District, Beijing 100085 (China)
2015-03-25
Highlights: • MALDI-FT-ICR-MS was firstly employed for molecular characterization of NOM. • 1,8-Bis(dimethyl-amino)-naphthalene (DMAN) was used as matrix. • Mass spectra of NOM generated by MALDI and ESI methods were compared. • Complementary molecular information of NOM was provided by MALDI. - Abstract: Natural organic matter (NOM) is a complex and non-uniform mixture of organic compounds which plays an important role in environmental processes. Due to the complexity, it is challenging to obtain fully detailed structural information about NOM. Although Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has been demonstrated to be a powerful tool for providing molecular information about NOM, multiple ionization methods are needed for comprehensive characterization of NOM at the molecular level considering the ionizing selectivity of different ionization methods. This paper reports the first use of matrix assisted laser desorption/ionization (MALDI) method coupled with FT-ICR-MS for molecular characterization of NOM within a mass range of 200–800 Da. The mass spectral data obtained by MALDI were systematically compared with data generated by electrospray ionization (ESI). It showed that complementary molecular information about NOM which could not be detected by ESI, were provided by MALDI. More unsaturated and aromatic constituents of NOM with lower O/C ratio (O/C ratio < 0.5) were preferentially ionized in MALDI negative mode, whereas more polar constituents of NOM with higher O/C ratio were preferentially ionized in ESI negative mode. Molecular anions of NOM appearing at even m/z in MALDI negative ion mode were detected. The results show that NOM molecules with aromatic structures, moderate O/C ratio (0.7 > O/C ratio > 0.25) and lower H/C ratio were liable to form molecular anions at even m/z, whereas those with higher H/C ratio are more likely to form deprotonated ions at odd m/z. It is speculated that almost half of the NOM
Riedel, Thomas; Dittmar, Thorsten
2014-08-19
Fourier Transform Ion Cyclotron Resonance mass spectra (FT-ICR-MS) of natural organic matter are complex and consist of several thousands of peaks. The corresponding mass to charge ratios (m/z) and signal intensities result from analytes and noise. The most commonly applied way of distinguishing between analyte and noise is a fixed signal-to-noise ratio below which a detected peak is considered noise. However, this procedure is problematic and can yield ambiguous results. For example, random noise peaks can occur slightly above the signal-to-noise threshold (false positives), while peaks of low abundance analytes may occasionally fall below the fixed threshold (false negatives). Thus, cumulative results from repeated measurements of the same sample contain more peaks than a single measurement. False positive and false negative signals are difficult to distinguish, which affects the reproducibility between replicates of a sample. To target this issue, we tested the feasibility of a method detection limit (MDL) for the analysis of natural organic matter to identify peaks that can reliably be distinguished from noise by estimating the uncertainty of the noise. We performed 556 replicate analyses of a dissolved organic matter sample from the deep North Pacific on a 15 T FT-ICR-MS; each of these replicate runs consisted of 500 cumulated broadband scans. To unambiguously identify analyte peaks in the mass spectra, the sample was also run at time-consuming high-sensitivity settings. The resulting data set was used to establish and thoroughly test a MDL. The new method is easy to establish with software help, does only require the additional analysis of replicate blanks (low time increase), and can implement all steps of sample preparation. Especially when analysis time does not allow for replicate runs, major merits of the MDL are reliable removal of false positive (noise) peaks and better reproducibility, while the risk of losing analytes with low signal intensities
Energy Technology Data Exchange (ETDEWEB)
Xu, Chen, E-mail: xuchen66@tamu.edu [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States); Chen, Hongmei [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); Sugiyama, Yuko [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); University of Hyogo, 1-1-12, Shinzaike-honcho, Himeji, Hyogo 670-0092 (Japan); Zhang, Saijin; Li, Hsiu-Ping; Ho, Yi-Fang; Chuang, Chia-ying; Schwehr, Kathleen A. [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States); Kaplan, Daniel I. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Yeager, Chris [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Roberts, Kimberly A. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Hatcher, Patrick G. [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); Santschi, Peter H. [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States)
2013-04-01
Major fractions of radioiodine ({sup 129}I) are associated with natural organic matter (NOM) in the groundwater and surface soils of the Savannah River Site (SRS). Electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was applied to elucidate the interactions between inorganic iodine species (iodide and iodate) and a fulvic acid (FA) extracted from a SRS surface soil. Iodate is likely reduced to reactive iodine species by the lignin- and tannin-like compounds or the carboxylic-rich alicyclic molecules (CRAM), during which condensed aromatics and lignin-like compounds were generated. Iodide is catalytically oxidized into reactive iodine species by peroxides, while FA is oxidized by peroxides into more aliphatic and less aromatic compounds. Only 9% of the total identified organo-iodine compounds derived from molecules originally present in the FA, whereas most were iodine binding to newly-produced compounds. The resulting iodinated molecules were distributed in three regions in the van Krevelen diagrams, denoting unsaturated hydrocarbons, lignin and protein. Moreover, characteristics of these organo-iodine compounds, such as their relatively low O/C ratios (< 0.2 or < 0.4) and yet some degree of un-saturation close to that of lignin, have multiple important environmental implications concerning possibly less sterically-hindered aromatic ring system for iodine to get access to and a lower hydrophilicity of the molecules thus to retard their migration in the natural aquatic systems. Lastly, ∼ 69% of the identified organo-iodine species contains nitrogen, which is presumably present as -NH{sub 2} or -HNCOR groups and a ring-activating functionality to favor the electrophilic substitution. The ESI-FTICR-MS technique provides novel evidence to better understand the reactivity and scavenging properties of NOM towards radioiodine and possible influence of NOM on {sup 129}I migration. Highlights: ► IO{sub 3}{sup
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.
De Bonis, Margherita; Bianco, Giuliana; Amati, Mario; Belviso, Sandra; Cataldi, Tommaso R I; Lelj, Francesco
2013-04-01
A new hexadentate, tripodal 8-hydroxyquinoline based ligand (QH3) and its gadolinium(III) tris-chelated (GdQ) complex with hemicage structure was investigated by using high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). The protonated adduct of the free ligand and its hemicage tripodal Gd(III) complex, [GdQ + H](+), were first observed in experiments of electrospray ionization (ESI) with a linear ion trap (LTQ) mass spectrometer and further investigated by using high resolution FTICRMS. Gas-phase dissociation of the protonated Gd(III) complex, by infrared multiphoton dissociation (IRMPD) FTICR MS, demonstrated a fragmentation pattern with six main product cluster ions labeled as [Fn](+) (n = 1 up to 6). These product ions suggest the elimination of 7-amino-alkyl or 7-alkyl chains of the hemicage moiety. High resolution MS conditions allowed the elucidation of the fragmentation pattern and product ion structures along with the determination, among the isotopic pattern of Gd, of the chemical compositions of closely related species, which differ in terms of hydrogen content. Among the Gd six naturally stable isotopes, (158)Gd is the most abundant, and its peak within each cluster was used as a reference for distinguishing each product ions. Computational DFT investigations were applied to give support to some hypothesis of fragmentation pathways, which could not have been easily justified on the basis of the experimental work. Furthermore, computational studies suggested the coordination geometry of the protonated parent complex and the five- and four-coordinated complexes, which derive from its fragmentation. Furthermore, experimental and computational evidences were collected about the octet spin state of the parent compound.
Institute of Scientific and Technical Information of China (English)
Cai Sheng Wu; Zhi Xin Jia; Bao Ming Ning; Jin Lan Zhang; Song Wu
2012-01-01
In this paper,a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry (HPLC-UV/FTICRMS) method was described for the investigation of impurity profile in moxifloxacin (MOX) drug substance and chemical reference substance.Ten impurities were detected by HPLC-UV,while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules.In addition,to our knowledge,five impurities were founded for the first time in MOX drug substance.
Directory of Open Access Journals (Sweden)
Mostafa Bashiri Juybari
2011-01-01
Full Text Available In this study dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO followed by gas chromatography-electron capture detection (GC-ECD was developed for determination of some pesticides in the water samples. Some important parameters, such as type and volumes of extraction and disperser solvent and salt effect on the extraction recovery of analytes from aqueous solution were investigated. Under the optimum conditions (extraction solvent: 1-undecanol, 15.0 μL; disperser solvent: acetone, 1.0 mL, and without salt addition, the preconcentration factors were obtained ranged from 802 to 915 for analytes. The linear ranges were from 0.05 to 100 μg L−1, and detection limits ranged from 0.05 to 0.008 μg L−1. The relative standard deviations (RSDs%, =5 were between 3.2% and 6.7%. The proposed method was successfully applied to the determination of target analytes in the tap, sea, and river water samples, and satisfactory recoveries were obtained.
Shi, Xizhi; Liu, Jinghua; Sun, Aili; Li, Dexiang; Chen, Jiong
2012-03-02
Two types of molecularly imprinted polymers (MIPs) for the simultaneous determination of six pyrethroid insecticides have been developed using deltamethrin (D-MIPs) and cypermethrin (C-MIPs) as template molecules. A comparison of the performance of D-MIPs, C-MIPs, and the corresponding non-imprinted polymers (NIPs) were conducted. Stronger group-selective interactions between the C-MIPs and the six pyrethroid insecticides were achieved. The MISPE method based on the C-MIPs displayed higher extraction recoveries (86.4-96.0%) with RSD values ranging from 2.4 to 7.8% for the six pyrethroid insecticides in aquaculture seawater. After the C-MIP cartridge procedure, the limits of detection and quantification for fenvalerate, deltamethrin, cypermethrin, cyfluthrin, and bifenthrin were in the 16.6-37.0 and 55.3-109.1 ng L⁻¹ ranges, respectively, and 0.68 and 2.26 μg L⁻¹ for phenothrin, respectively. The proposed MISPE method coupled with gas chromatography-electron capture detection was successfully used for the determination of the six pyrethroid insecticides in aquaculture seawater.
Zhou, Qingxiang; Wu, Wei; Xie, Guohong
2013-01-01
The goal of the present study was to investigate the feasibility of silicon dioxide (SiO(2)) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-dichlorodiphenyl-2,2-dichloroethylene (p,p'-DDD) and p,p'-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2-30 ng mL(-1) and the correlation coefficients were in the range of 99.96-99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT, and p,p'-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4-112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment.
Directory of Open Access Journals (Sweden)
Ganesh Muguli
2015-01-01
Full Text Available "Triphalaguggulu0" is an important Ayurvedic formulation comprising of Guggulu, that is, Commiphora wightii (Arn. Bhandari as a base wherein powdered fruits of triphala, that is, Phyllanthus emblica L., Terminalia bellirica (Gaertn. Roxb and Terminalia chebula Retz, along with powdered fruit of Piper longum L. are compounded. This polyherbal preparation has been strongly recommended in chronic inflammation, piles, and fistula. However, due to the complexity of compound formulation standardization of commercial products is challenging. In the present communication marker-based standardization of "Triphalaguggulu" preparation using gallic acid (for triphala, piperine (for P. longum L. and guggulsterones (for guggulu is reported. These compounds of diverse chemistry were successfully separated on a Waters HR-C18 column by isocratic elution with methanol and water (80:20 v/v as mobile phase at the flow rate of 1.0 mL/min coupled with photodiode array detector. These optimal chromatographic conditions were used for simultaneous quantification of gallic acid, guggulsterones (E and Z and piperine in commercial samples by high-performance liquid chromatography-electron spray ionization-mass spectrometry and method was validated as per ICH guidelines.
Shi, Xizhi; Tang, Zigang; Sun, Aili; Zhou, Lei; Zhao, Jian; Li, Dexiang; Chen, Jiong; Pan, Daodong
2014-12-01
A highly efficient and environment-friendly membrane-assisted solvent extraction system combined with gas chromatography-electron capture detector was applied in the simultaneous determination of 17 polychlorinated biphenyls and organochlorine pesticides in seawater samples. Variables affecting extraction efficiency, including extraction solvent used, stirring rate, extraction time, and temperature, were optimized extensively. Under optimal extraction conditions, recoveries between 76.9% and 104.6% in seawater samples were achieved, and relative standard deviation values below 10% were obtained. The limit of detection (signal-to-noise ratio=3) and limit of quantification (signal-to-noise ratio=10) of 17 polychlorinated biphenyls and organochlorine pesticides in seawater ranged from 0.14ngL(-1) to 0.36ngL(-1) and 0.46ngL(-1) to 1.19ngL(-1), respectively. Matrix effects on extraction efficiency were evaluated by comparing with the results obtained using tap water. The extraction effect of developed membrane-assisted solvent extraction method was further demonstrated by gas chromatography-tandem mass spectrometry which can provide structural information of the analytes for more accurate identification, and results identical to those produced by gas chromatography-electron capture detector were obtained. These findings demonstrate the applicability of the developed membrane-assisted solvent extraction determination method for coupling to gas chromatography-electron capture detector or tandem mass spectrometry for determining polychlorinated biphenyls and organochlorine pesticides in seawater samples.
Energy Technology Data Exchange (ETDEWEB)
Hu Jia [Department of Chemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Central China Normal University, Wuhan 430079 (China); Fu Lingyan; Zhao Xinna; Liu Xiujuan [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Central China Normal University, Wuhan 430079 (China); Wang Huili; Wang Xuedong [School of Environmental Science and Public Health, Wenzhou Medical College, Wenzhou 325035 (China); Dai Liyan, E-mail: dailiyan@zju.edu.cn [Department of Chemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China)
2009-04-27
In this article, dispersive liquid-liquid microextraction (DLLME) and gas chromatography-electron capture detection (GC-ECD) were presented for the extraction and determination of five polychlorinated biphenyls (PCBs) in soil samples. Acetone was used as extraction solvent for the extraction of PCBs from soil samples. In DLLME, the target analytes in the extraction solvent were rapidly transferred from the acetone extract to chlorobenzene when the extraction process began. The main advantages of this method are quick speed, high enrichment factor, high recovery and good repeatability. Under the optimum conditions, the method yields a linear calibration curve in the concentration range from 2 to 2000 {mu}g kg{sup -1}for PCB 52, and 0.4 to 400 {mu}g kg{sup -1} for other target analytes. Coefficients of correlation (r{sup 2}) ranged from 0.9993 to 0.9999. The repeatability was tested by spiking soil samples at a concentration level of 10 {mu}g kg{sup -1} for PCBs. The relative standard deviations (RSDs, n = 11) varied between 2.2% and 6.4%. The limits of detection (LODs), based on signal-to-noise (S/N) of 3, were between 0.20 and 0.50 {mu}g kg{sup -1}. The relative recoveries of the five PCBs from soil S1, S2 and S3 at spiking levels of 10, 20 and 50 {mu}g kg{sup -1} were in the range of 88.70-103.8%, 82.50-106.3% and 82.30-113.6%, respectively. Therefore, DLLME combined with GC-ECD can be successfully applied for the determination of trace PCB residues in real soil samples.
Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Varshney, Meenu; Ch, Ratnasekhar; Chauhan, Abhishek; Goyal, Sudhir Kumar; Khan, Haider A; Murthy, R C
2013-04-15
Trichloroethylene (TCE) is a common industrial chemical that has been widely used as metal degreaser and for many industrial purposes. In humans, TCE is metabolized into dichloroacetic acid (DCA), trichloroacetic acid (TCA) and trichloroethanol (TCOH). A simple and rapid method has been developed for the quantitative determination of TCE metabolites. The procedure involves the in situ derivatization of TCE metabolites with methyl chloroformate (MCF) directly in diluted plasma samples followed by extraction and analysis with solid-phase microextraction (SPME) coupled to gas chromatography-electron capture detector (GC-ECD). Factors which can influence the efficiency of derivatization such as amount of MCF and pyridine (PYR), ratio of water/methanol were optimized. The factors which can affect the extraction efficiencies of SPME were screened using 2(7-4) Placket-Burman Design (PBD). A central composite design (CCD) was then applied to further optimize the most significant factors for optimum SPME extraction. The optimum factors for the SPME extraction were found to be 562.5mg of NaCl, pH at 1 and an extraction time of 22 min. Recoveries and detection limits of all three analytes in plasma were found to be in the range of 92.69-97.55% and 0.036-0.068 μg mL(-1) of plasma, respectively. The correlation coefficients were found to be in the range of 0.990-0.995. The intra- and inter-day precisions for TCE metabolites were found to be in the range of 2.37-4.81% and 5.13-7.61%, respectively. The major advantage of this method is that MCF derivatization allows conversion of TCE metabolites into their methyl esters in very short time (≤30 s) at room temperature directly in the plasma samples, thus makes it a solventless analysis. The method developed was successfully applied to the plasma samples of humans exposed to TCE.
Engle, Jonathan
2013-01-01
The spin foam framework provides a way to define the dynamics of canonical loop quantum gravity in a spacetime covariant way, by using a path integral over histories of quantum states which can be interpreted as `quantum space-times'. This chapter provides a basic introduction to spin foams aimed principally at beginning graduate students and, where possible, at broader audiences.
TOPICAL REVIEW: Spin current, spin accumulation and spin Hall effect
Directory of Open Access Journals (Sweden)
Saburo Takahashi and Sadamichi Maekawa
2008-01-01
Full Text Available Nonlocal spin transport in nanostructured devices with ferromagnetic injector (F1 and detector (F2 electrodes connected to a normal conductor (N is studied. We reveal how the spin transport depends on interface resistance, electrode resistance, spin polarization and spin diffusion length, and obtain the conditions for efficient spin injection, spin accumulation and spin current in the device. It is demonstrated that the spin Hall effect is caused by spin–orbit scattering in nonmagnetic conductors and gives rise to the conversion between spin and charge currents in a nonlocal device. A method of evaluating spin–orbit coupling in nonmagnetic metals is proposed.
Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael
2004-01-01
This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...
Directory of Open Access Journals (Sweden)
Luciano Aparecido Xavier
2001-06-01
Full Text Available This article shows the usefulness of a website to explain the concepts, operational events, vacuum system, applications and an experimental sequence of the Fourier Transform Ion Ciclotron Resonance Mass Spectrometry technique (http://143.107.46.113/icr/icrj.html.
Kong, H.; Wang, M.; Venema, K.; Maathuis, A.; Heijden, R. van der; Greef, J. van der; Xu, G.; Hankemeier, T.
2009-01-01
A high-performance liquid chromatography-high resolution Fourier transform ion cyclotron resonance mass spectrometry (HPLC-FTICR-MS) method was developed to investigate the metabolism of ginsenosides in in vitro models of the gastro-intestinal tract. The metabolites were identified by high-resolutio
Wang, Meng; Zhao, Suoqi; Liu, Xuxia; Shi, Quan
2016-10-04
Thiols widely occur in sediments and fossil fuels. However, the molecular composition of these compounds is unclear due to the lack of appropriate analytical methods. In this work, a characterization method for thiols in fossil fuels was developed on the basis of Michael addition reaction derivatization followed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Model thiol compound studies showed that thiols were selectively reacted with phenylvinylsulfone and transformed to sulfones with greater than 98% conversions. This method was applied to a coker naphtha, light and heavy gas oils, and crude oils from various geological sources. The results showed that long alkyl chain thiols are readily present in petroleum, which have up to 30 carbon atoms. Large DBE dispersity of thiols indicates that naphthenic and aromatic thiols are also present in the petroleum. This method is capable of detecting thiol compounds in the part per million range by weight. This method allows characterization of thiols in a complex hydrocarbon matrix, which is complementary to the comprehensive analysis of sulfur compounds in fossil fuels.
Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan
2013-01-01
Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.
Qian, Kuangnan; Mennito, Anthony S; Edwards, Kathleen E; Ferrughelli, Dave T
2008-07-01
Vanadyl (VO) porphyrins and sulfur-containing vanadyl (VOS) porphyrins of a wide carbon number range (C(26) to C(52)) and Z-number range (-28 to -54) were detected and identified in a petroleum asphaltene by atmospheric pressure photonionization (APPI) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). APPI provides soft ionization of asphaltene molecules (including VO and VOS porphyrins), generating primarily molecular ions (M(+.)). The ultra-high mass resolving power (m/Delta m(FWHM) approximately 500 K) of FTICR-MS enabled resolution and positive identification of elemental formulae for the entire family of VO and VOS porphyrins in a complicated asphaltene matrix. Deocophylerythro-etioporphyrin (DPEP) is found to be the most prevalent structure, followed by etioporphyrins (etio)- and rhodo (benzo)-DPEP. The characteristic Z-distribution of VO porphyrins suggests benzene and naphthene increment in the growth of porphyrin ring structures. Bimodal carbon number distributions of VO porphyrins suggest possible different origins of low and high molecular weight species. To our knowledge, the observation of VOS porphyrins in a petroleum product has not previously been reported. The work is also the first direct identification of the entire vanadyl porphyrin family by ultra-high resolution mass spectrometry without chromatographic separation or demetallation.
Carlsohn, Elisabet; Ångström, Jonas; Emmett, Mark R.; Marshall, Alan G.; Nilsson, Carol L.
2004-05-01
Chemical cross-linking of proteins is a well-established method for structural mapping of small protein complexes. When combined with mass spectrometry, cross-linking can reveal protein topology and identify contact sites between the peptide surfaces. When applied to surface-exposed proteins from pathogenic organisms, the method can reveal structural details that are useful in vaccine design. In order to investigate the possibilities of applying cross-linking on larger protein complexes, we selected the urease enzyme from Helicobacter pylori as a model. This membrane-associated protein complex consists of two subunits: [alpha] (26.5 kDa) and [beta] (61.7 kDa). Three ([alpha][beta]) heterodimers form a trimeric ([alpha][beta])3 assembly which further associates into a unique dodecameric 1.1 MDa complex composed of four ([alpha][beta])3 units. Cross-linked peptides from trypsin-digested urease complex were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and molecular modeling. Two potential cross-linked peptides (present in the cross-linked sample but undetectable in [alpha], [beta], and native complex) were assigned. Molecular modeling of urease [alpha][beta] complex and trimeric urease units ([alpha][beta])3 revealed a linkage site between the [alpha]-subunit and the [beta]-subunit, and an internal cross-linkage in the [beta]-subunit.
Han, Fei; Li, Yanting; Mao, Xinjuan; Xu, Rui; Yin, Ran
2016-05-01
In this work, an approach using high-performance liquid chromatography coupled with diode-array detection and Fourier-transform ion cyclotron resonance mass spectrometer (HPLC-FT-ICR MS) for the identification and profiling of chemical constituents in Rhodiola crenulata was developed for the first time. The chromatographic separation was achieved on an Inertsil ODS-3 column (150 mm × 4.6 mm,3 µm) using a gradient elution program, and the detection was performed on a Bruker Solarix 7.0 T mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 48 chemical compounds, including 26 alcohols and their glycosides, 12 flavonoids and their glycosides, 5 flavanols and gallic acid derivatives, 4 organic acids and 1 cyanogenic glycoside were identified or tentatively characterized. The results indicated that the developed HPLC-FT-ICR MS method with ultra-high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents in R. crenulata. And it provides a helpful chemical basis for further research on R. crenulata. Copyright © 2016 John Wiley & Sons, Ltd.
Weinbuch, Daniel; Zölls, Sarah; Wiggenhorn, Michael; Friess, Wolfgang; Winter, Gerhard; Jiskoot, Wim; Hawe, Andrea
2013-07-01
Our study aimed to comparatively evaluate Micro-Flow Imaging (MFI) and the recently introduced technique of resonant mass measurement (Archimedes, RMM) as orthogonal methods for the quantitative differentiation of silicone oil droplets and protein particles. This distinction in the submicron and micron size range is highly relevant for the development of biopharmaceuticals, in particular for products in prefilled syringes. Samples of artificially generated silicone oil droplets and protein particles were quantified individually and in defined mixtures to assess the performance of the two techniques. The built-in MFI software solution proved to be suitable to discriminate between droplets and particles for sizes above 2 μm at moderate droplet/particle ratios (70:30-30:70). A customized filter developed specifically for this study greatly improved the results and enabled reliable discrimination also for more extreme mixing ratios (95:5-15:85). RMM showed highly accurate discrimination in the size range of about 0.5-2 μm independent of the ratio, provided that a sufficient number of particles (>50 counted particles) were counted. We recommend applying both techniques for a comprehensive analysis of biotherapeutics potentially containing silicone oil droplets and protein particles in the submicron and micron size range.
Institute of Scientific and Technical Information of China (English)
Wang Wei; Liu Yingrong; Liu Zelong; Tian Songbai
2015-01-01
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has become a powerful tool for ana-lyzing the detailed composition of petroleum samples. However, the correlation between the numerous peaks obtained by FT-ICR MS and bulk properties of petroleum samples is still a challenge. In this study, the internal standard method was applied for the quantitative analysis of four straight-run vacuum gas oils (VGO) by atmospheric pressure photoionization (APPI) FT-ICR MS. The heteroatom class distribution of these VGO samples turned to be different when the concentration changed. Linear relationship between the normalized abundance and the concentration of VGO samples was identiifed for the total aromatic compounds, aromatic hydrocarbons, S1 and N1 species. The differences of the response factors were also discussed. The sulfur contents of a series of crude oils were proved to be linear with the FT-ICR MS data calibrated by the response factor of S1 species. This study demonstrated the feasibility of the internal standard method in quantitative analysis with APPI FT-ICR MS, and the bulk properties of petroleum samples could be correlated directly with the FT-ICR MS data.
Farenc, Mathilde; Witt, Matthias; Craven, Kirsten; Barrère-Mangote, Caroline; Afonso, Carlos; Giusti, Pierre
2017-01-01
Polyolefins such as polyethylene (PE) and polypropylene (PP) are often characterized from their pyrolysis products by Py-MS. Nowadays the development of plasma-based direct probe atmospheric pressure sources allow the direct analysis of these polymers. These sources operate at atmospheric pressure, which implies a limited control of the ionization conditions. It was shown that side reactions could occur with species present in air, such as O2, which may lead to the formation of oxidized compounds. In this work, ion mobility-mass spectrometry (IM-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR) were used for the exhaustive characterization of the PP and PE pyrolysis ions produced using plasma-based atmospheric pressure ion sources. Both PP and PE yielded distributions of pyrolysis products presenting different amounts of unsaturation but also different numbers of oxygen atoms. In addition, the ions produced from PP presented a lower collision cross-section (CCS) than those produced from PE. In the same way, both PP and PE present repeated patterns separated by 14 m/z in the bidimensional drift time versus m/z plots. Within these plots, several trend lines can be evidenced, which are specific of each polymer investigated. Differences were observed between isotactic and atactic samples concerning the pyrolysis profile relative abundance and collision cross-section.
Classical gravitational spin-spin interaction
Bonnor, W. B.
2002-01-01
I obtain an exact, axially symmetric, stationary solution of Einstein's equations for two massless spinning particles. The term representing the spin-spin interaction agrees with recently published approximate work. The spin-spin force appears to be proportional to the inverse fourth power of the coordinate distance between the particles.
Spin-Orbit induced semiconductor spin guides
Valin-Rodriguez, Manuel; Puente, Antonio; Serra, Llorens
2002-01-01
The tunability of the Rashba spin-orbit coupling allows to build semiconductor heterostructures with space modulated coupling intensities. We show that a wire-shaped spin-orbit modulation in a quantum well can support propagating electronic states inside the wire only for a certain spin orientation and, therefore, it acts as an effective spin transmission guide for this particular spin orientation.
Sun, Qing-feng; Guo, Hong; Wang, Jian
2003-06-27
We propose and investigate a spin-cell device which provides the necessary spin-motive force to drive a spin current for future spintronic circuits. Our spin cell has four basic characteristics: (i) it has two poles so that a spin current flows in from one pole and out from the other pole, and in this way a complete spin circuit can be established; (ii) it has a source of energy to drive the spin current; (iii) it maintains spin coherence so that a sizable spin current can be delivered; (iv) it drives a spin current without a charge current. The proposed spin cell for spin current should be realizable using technologies presently available.
Spin squeezing in nonlinear spin coherent states
Wang, Xiaoguang
2001-01-01
We introduce the nonlinear spin coherent state via its ladder operator formalism and propose a type of nonlinear spin coherent state by the nonlinear time evolution of spin coherent states. By a new version of spectroscopic squeezing criteria we study the spin squeezing in both the spin coherent state and nonlinear spin coherent state. The results show that the spin coherent state is not squeezed in the x, y, and z directions, and the nonlinear spin coherent state may be squeezed in the x and...
Nyakas, Adrien; Han, Jun; Peru, Kerry M; Headley, John V; Borchers, Christoph H
2013-05-07
Oil sands processed water (OSPW) is the main byproduct of the large-scale bitumen extraction activity in the Athabasca oil sands region (Alberta, Canada). We have investigated the acid-extractable fraction (AEF) of OSPW by extraction-only (EO) direct infusion (DI) negative-ion mode electrospray ionization (ESI) on a 12T-Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS), as well as by offline ultrahigh performance liquid chromatography (UHPLC) followed by DI-FTICR-MS. A preliminary offline UHPLC separation into 8 fractions using a reversed-phase C4 column led to approximately twice as many detected peaks and identified compounds (973 peaks versus 2231 peaks, of which 856 and 1734 peaks, respectively, could be assigned to chemical formulas based on accurate mass measurements). Conversion of these masses to the Kendrick mass scale allowed the straightforward recognition of homologues. Naphthenic (CnH2n+zO2) and oxy-naphthenic (CnH2n+zOx) acids represented the largest group of molecules with assigned formulas (64%), followed by sulfur-containing compounds (23%) and nitrogen-containing compounds (8%). Pooling of corresponding fractions from two consecutive offline UHPLC runs prior to MS analysis resulted in ~50% more assignments than a single injection, resulting in 3-fold increase of identifications compared to EO-DI-FTICR-MS using the same volume of starting material. Liquid-liquid extraction followed by offline UHPLC fractionation thus holds enormous potential for a more comprehensive profiling of OSPW, which may provide a deeper understanding of its chemical nature and environmental impact.
Payne, Tristan G; Southam, Andrew D; Arvanitis, Theodoros N; Viant, Mark R
2009-06-01
Direct-infusion electrospray-ionization Fourier transform ion cyclotron resonance mass spectrometry (DI ESI FT-ICR MS) is increasingly being utilized in metabolomics, including the high sensitivity selected ion monitoring (SIM)-stitching approach. Accurate signal quantification and the discrimination of real signals from noise remain major challenges for this approach, with both adversely affected by factors including ion suppression during electrospray, ion-ion interactions in the detector cell, and thermally-induced white noise. This is particularly problematic for complex mixture analysis where hundreds of metabolites are present near the noise level. Here we address relative signal quantification and noise discrimination issues in SIM-stitched DI ESI FT-ICR MS-based metabolomics. Using liver tissue, we first optimized the number of scans (n) acquired per SIM window to address the balance between quantification accuracy versus acquisition time (and thus sample throughput); a minimum of n = 5 is recommended. Secondly, we characterized and computationally-corrected an effect whereby an ion's intensity is dependent upon its location within a SIM window, exhibiting a 3-fold higher intensity at the high m/z end. This resulted in significantly improved quantification accuracy. Finally, we thoroughly characterized a three-stage filter to discriminate noise from real signals, which comprised a signal-to-noise-ratio (SNR) hard threshold, then a "replicate" filter (retaining only peaks in r-out-of-3 replicate analyses), and then a "sample" filter (retaining only peaks in >s% of biological samples). We document the benefits of three-stage filtering versus one- and two-stage filters, and show the importance of selecting filter parameters that balance the confidence that a signal is real versus the total number of peaks detected.
Whitelegge, Julian P.; Zabrouskov, Vlad; Halgand, Frederic; Souda, Puneet; Bassilian, Sara; Yan, Weihong; Wolinsky, Larry; Loo, Joseph A.; Wong, David T. W.; Faull, Kym F.
2007-12-01
Single nucleotide polymorphisms (SNPs) can result in protein-sequence polymorphisms (PSPs) when codon translations are altered. Both top-down and bottom-up proteomics strategies can identify PSPs, but only if databases and software are used with this in mind. A 14,319 Da protein from human saliva was characterized using the top-down approach on a hybrid linear ion-trap Fourier-transform ion cyclotron resonance mass spectrometer equipped for both collisionally activated (CAD) and electron-capture (ECD) dissociation. Sequence tags identified the protein as Cystatin SN, and defined the N-terminal signal peptide cleavage site, as well as two disulfide bonds, in agreement with previous studies. The mass of the intact protein (published gene sequence by 16.031 Da, and, based on CAD and ECD fragment ion assignments, it was concluded that the isoform of the protein analyzed carried a PSP at residue 11 such that the Pro translated from the genome was in fact Leu/Ile. An independently determined SNP (rs2070856) subsequently confirmed the genetic basis of the mass spectral interpretation and defined the residue as Leu. In another example, the PRP3 protein with mass ~10,999 Da was found to be an isomeric/isobaric mixture of the reported sequence with PSPs D4N or D50N (rs1049112). Both CAD and ECD datasets support two phosphorylation sites at residues Ser8 and Ser22, rather than Ser17. In the context of discovery proteomics, previously undefined PSPs and PTMs will only be detected if the logic of data processing strategies considers their presence in an unbiased fashion.
Directory of Open Access Journals (Sweden)
R. M. Dickhut
2008-09-01
Full Text Available Despite the acknowledged relevance of aerosol-derived water-soluble organic carbon (WSOC to climate and biogeochemical cycling, characterization of aerosol WSOC has been limited. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS was utilized in this study to provide detailed molecular level characterization of the high molecular weight (HMW; m/z>223 component of aerosol-derived WSOC collected from rural sites in Virginia and New York, USA. More than 3000 peaks were detected by ESI FT-ICR MS within a m/z range of 223–600 for each sample. Approximately 86% (Virginia and 78% (New York of these peaks were assigned molecular formulas using only carbon (C, hydrogen (H, oxygen (O, nitrogen (N, and sulfur (S as elemental constituents. H/C and O/C molar ratios were plotted on van Krevelen diagrams and indicated a strong contribution of lignin-like and lipid-like compounds to the aerosol-derived WSOC samples. Approximately 1–4% of the peaks in the aerosol-derived WSOC mass spectra were classified as black carbon (BC on the basis of double bond equivalents calculated from the assigned molecular formulas. In addition, several high-magnitude peaks in the mass spectra of samples from both sites corresponded to molecular formulas proposed in previous secondary organic aerosol (SOA laboratory investigations indicating that SOAs are important constituents of the WSOC. Overall, ESI FT-ICR MS provides a level of resolution adequate for detailed compositional and source information of the HMW constituents of aerosol-derived WSOC.
Brahms, N
2010-01-01
The dynamics of a large quantum spin coupled parametrically to an optical resonator is treated in analogy with the motion of a cantilever in cavity optomechanics. New spin optodynamic phenonmena are predicted, such as cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent amplification and damping of spin, and the spin optodynamic squeezing of light.
Priest, A. S.; Wozniak, A. S.; Hatcher, P. G.
2011-12-01
There is strong evidence that suggests emissions from human activities have played a substantial role in changing the chemical composition of the atmosphere, resulting in negative effects on climate and human and environmental health. Theory suggests that the molecular composition of organic aerosols plays a role in the specific impacts; however, due to the lack of suitable analytical methods for characterizing the inherently complex aerosol organic matter (OM), our molecular level understanding of the nature and reactivity of this material has been limited. Ultra-high resolution mass spectrometry has provided molecular formula information for thousands of species present in the water-soluble fraction of organic aerosols. However, fewer studies have examined the water-insoluble fraction, which typically accounts for 30-70% of aerosol OM. Here we employ pyridine, with its high solvating power for natural OM, as a suitable solvent for examining the water-insoluble fraction of field-collected organic aerosols using ultra-high resolution mass spectrometry. The molecular composition of the water-soluble organic matter (WSOM) and pyridine-soluble organic matter (PSOM) of organic aerosols was evaluated using negative ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Ambient aerosol samples were collected from rural sites in New York and Virginia in 2007. The mass spectral distribution of the ions detected using ESI FT-ICR MS allowed for the determination of molecular formulas for the thousands of peaks detected in each extract. Approximately 40% of the aerosol OM was WSOM, and the spectra were dominated by compounds with only carbon, hydrogen and oxygen (~45% of assigned formulas), with relatively smaller contributions from nitrogen- and sulfur-containing formulas. Pyridine, on the other hand, extracts a molecularly unique portion of aerosol OM. Approximately 25% of the formulas are unique to PSOM, and the
Gordon, E F; Mansoori, B A; Carroll, C F; Muddiman, D C
1999-10-01
The number of publications documenting the utility of electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) for the analysis of biological molecules has increased in geometric proportion spanning diverse areas of research. Currently, we are investigating the capabilities of ESI-FTICR to quantify relative molecular ion abundances of biopolymers, an area which has not been explored rigorously. We present here the results of an investigation of a two-component system utilizing equine heart cytochrome c (EH) as the analyte and bovine heart cytochrome c (BH) as a constant concentration internal standard. As these compounds are relatively large ( approximately 12 kDa), they will become multiply charged during the electrospray process. Using appropriate solution and instrument conditions, the 7(+) and 8(+) charge states were enhanced for both cytochrome c species. We report that using the average of the ion abundances for the two charge states observed for each species, the linear curve (intensity ratio vs concentration ratio) had a dynamic range of 0.045-2.348 microM (1.7 orders of magnitude). Linear least-squares regression analysis (LLSRA) of these averaged ion abundances (i.e. [(EH + 7H(+))(7+)/(BH + 7H(+))(7+) + (EH + 8H(+))(8+)/(BH + 8H(+))(8+)]/2) yielded the equation y = 1.005x + 0.027. The slope of the line with its calculated precision, reported as one standard deviation, is 1.005 +/- 0.0150, which is statistically ideal (i.e. equal to unity). However, LLSRA of the ion abundances of the two individual charge states were significantly different (i.e. the slope of the (EH + 7H(+))(7+)/(BH + 7H(+))(7+) peak intensity ratio vs molar ratio data was 0.885 +/- 0.0183 and the slope of the (EH + 8H(+))(8+)/(BH + 8H(+))(8+) data was 1.125 +/- 0.0308). We attribute this difference to the variation in primary amino acid sequence for the two cytochrome c species. Both have 104 amino acids, but there are three residue
Headley, J V; Barrow, M P; Peru, K M; Fahlman, B; Frank, R A; Bickerton, G; McMaster, M E; Parrott, J; Hewitt, L M
2011-07-15
There is a growing need to develop analytical methods that can distinguish compounds found within industrially derived oil sands process water (OSPW) from those derived from natural weathering of oil sands deposits. This is a difficult challenge as possible leakage beyond tailings pond containments will probably be in the form of mixtures of water-soluble organics that may be similar to those leaching naturally into aquatic environments. We have evaluated the potential of negative ion electrospray ionization high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) for comparing oil sands polar organics from tailing ponds, interceptor wells, groundwater, river and lake surface waters. Principal component analysis was performed for all species observed. which included the O(2) class (often assumed to be monocarbxoylic naphthenic acids) along with a wide range of other species including humic substances in the river and lake samples: O(n) where n=1-16; NO(n) and N(2)O(n) where n=1-13; and O(n)S and O(n)S(2) where n=1-10 and 1-8, respectively. A broad range of species was investigated because classical naphthenic acids can be a small fraction of the 'organics' detected in the polar fraction of OSPW, river water and groundwater. Aquatic toxicity and environmental chemistry are attributed to the total organics (not only the classical naphthenic acids). The distributions of the oil sands polar organics, particularly the sulfur-containing species, O(n)S and O(n)S(2), may have potential for distinguishing sources of OSPW. The ratios of species containing O(n) along with nitrogen-containing species: NO(n), and N(2)O(n), were useful for differentiating organic components derived from OSPW from those found in river and lake waters. Further application of the FTICRMS technique for a diverse range of OSPW of varying ages and composition, as well as the surrounding groundwater wells, may be critical in assessing whether leakage from industrial sources
Nepomuceno, Angelito I; Muddiman, David C; Bergen, H Robert; Craighead, James R; Burke, Michael J; Caskey, Patrick E; Allan, Jonathan A
2003-07-15
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has rapidly established a prominent role in proteomics because of its unparalleled resolving power, sensitivity and ability to achieve high mass measurement accuracy (MMA) simultaneously. However, space-charge effects must be quantitatively, routinely, and confidently corrected because they are known to profoundly influence MMA. We argue that the most effective way to account for space-charge effects is to introduce an internal mass calibrant (IMC) using a dual electrospray ionization (ESI) source where the IMC is added from a separate ESI emitter. The major disadvantage of our initial dual ESI source to achieve high MMA, and arguably the only one, was the time required to switch between the analyte emitter and IMC emitter (i.e., >300 ms). While this "switching time" was acceptable for direct infusion experiments, it did not lend itself to high-throughput applications or when conducting on-line liquid separations. In this report, we completely redesigned the dual ESI source and demonstrate several key attributes. First, the new design allows for facile alignment of ESI emitters, undetectable vibration, and the ability to extend to multiple emitters. Second, the switching time was reduced to IMC to be accumulated "simultaneously" in the external ion reservoir and injected as a single ion packet into the ion cyclotron resonance cell, eliminating the need for a separate accumulation and ion injection event for the IMC. Third, by using a high concentration of the IMC, the residence time on this emitter could be reduced to approximately 80 ms, allowing for more time spent accumulating analyte ions of significantly lower concentration. Fourth, multiplexed on-line separations can be carried out providing increased throughput. Specifically, the new dual ESI source has demonstrated its ability to produce a stable ion current over a 45-min time period at 7 T resulting in mass accuracies of 1.08 ppm +/- 0
Institute of Scientific and Technical Information of China (English)
ZHANG Peng-Fei; RUAN Tu-Nan
2001-01-01
A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativistic one, which is called in this paper as moving spin. Further the concept of moving spin is discussed in the quantum field theory. A new is constructed. It is shown that, in virtue of the two operators, problems in quantum field concerned spin can be neatly settled.
Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; Waggoner, Derek C.; Almendros, Gonzalo; González-Vila, Francisco J.; Hatcher, Patrick G.
2016-04-01
Introduction: Fire is one of the most important modulator factors of the environment and the forest. It is able to induce chemical and biological shifts and these, in turn, can alter the physical properties of soil. Generally, fire affects the most reactive fraction, soil organic matter (SOM) (González-Pérez et al., 2004) resulting in changes to several soil properties and functions. To study changes in SOM following a wildfire, researchers can count on several traditional as well as new analytical techniques. One of the most recently employed techniques is Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). This new powerful ultra-high resolution mass spectral technique, together with graphic interpretation tools such as van Krevelen diagrams (Kim et al, 2003), may be used to shed light on alterations caused by the burning of SOM. The objective of this research is to study fire impacts on SOM, using a sandy soil collected under a Cork oak (Quercus suber) in Doñana National Park, Southwest Spain. that was affected by a wildfire in August 2012. Methods: The impact of fire on SOM was studied in various different sieve fractions (coarse, 1-2 mm, and fine, organic matter. The presence of molecular formulas which plot in the aromatic and condensed aromatics regions also indicates that this fraction may have contributions from a second, more recalcitrant, organic carbon pool. The appearance of aromatic and condensed aromatic compounds could suggest that, in this fraction the fire induced condensation processes. In the burnt fine fraction, two different SOM sources of alteration could be identified; i) from microbial origin with high relative intensity of lipid-like and protein-like compounds and ii) fire origin with large amounts of condensed aromatic compounds and a high contribution from the carbohydrate-like compounds region. We suggest that these results indicate both, condensation processes yielding black carbon like materials and additions
Institute of Scientific and Technical Information of China (English)
李树奇; 鲍晓迪; 殷红; 孔祥蕾
2015-01-01
对傅里叶变换离子回旋共振高分辨率质谱仪的发展历程、串联质谱解离技术及最新的应用进行了详细描述，并对其发展趋势进行了展望。%The history and development of Fourier transform ion cyclotron resonance mass spectrometer ( FT ICR MS) is presented in detail. The dissociation technique for tandem mass spectrometry and the latest application are in-troduced. The development trend of FT ICR MS is discussed.
Magnetic Nanostructures Spin Dynamics and Spin Transport
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.
Decoherence dynamics of a single spin versus spin ensemble
Dobrovitski, V.V.; Feiguin, A.E.; Awschalom, D.D.; Hanson, R.
2008-01-01
We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian free-induct
Entangled spins and ghost-spins
Jatkar, Dileep P
2016-01-01
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 arXiv:1602.06505 [hep-th] 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 gho...
Magnons, Spin Current and Spin Seebeck Effect
Maekawa, Sadamichi
2012-02-01
When metals and semiconductors are placed in a temperature gradient, the electric voltage is generated. This mechanism to convert heat into electricity, the so-called Seebeck effect, has attracted much attention recently as the mechanism for utilizing wasted heat energy. [1]. Ferromagnetic insulators are good conductors of spin current, i.e., the flow of electron spins [2]. When they are placed in a temperature gradient, generated are magnons, spin current and the spin voltage [3], i.e., spin accumulation. Once the spin voltage is converted into the electric voltage by inverse spin Hall effect in attached metal films such as Pt, the electric voltage is obtained from heat energy [4-5]. This is called the spin Seebeck effect. Here, we present the linear-response theory of spin Seebeck effect based on the fluctuation-dissipation theorem [6-8] and discuss a variety of the devices. [4pt] [1] S. Maekawa et al, Physics of Transition Metal Oxides (Springer, 2004). [0pt] [2] S. Maekawa: Nature Materials 8, 777 (2009). [0pt] [3] Concept in Spin Electronics, eds. S. Maekawa (Oxford University Press, 2006). [0pt] [4] K. Uchida et al., Nature 455, 778 (2008). [0pt] [5] K. Uchida et al., Nature Materials 9, 894 (2010) [0pt] [6] H. Adachi et al., APL 97, 252506 (2010) and Phys. Rev. B 83, 094410 (2011). [0pt] [7] J. Ohe et al., Phys. Rev. B (2011) [0pt] [8] K. Uchida et al., Appl. Phys. Lett. 97, 104419 (2010).
Spin-polarized spin excitation spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J, E-mail: lothseb@us.ibm.com, E-mail: heinrich@almaden.ibm.com [IBM Research Division, Almaden Research Center, San Jose, CA 95120 (United States)
2010-12-15
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{sub 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.
Shi, Loimeng; Gao, Yuan; Hou, Xiaohong; Zhang, Haijun; Zhang, Yichi; Chen, Jiping
2016-02-01
An analytical method for quantifying short-chain chlorinated paraffins (SCCPs) in ambient air using high-volume sampling combined with high resolution gas chromatography-electron capture negative ion-low resolution mass spectrometry ( HRGC-ECNI-LRMS) was developed. An acidified silica gel column and a basic alumina column were used to optimize the cleanup procedures. The results showed a good linearity (R2>0. 99) between the total response factors and the degree of chlorination of SCCPs in the content range of 58. 1%-63. 3%. The limits of detection (S/N ≥3) and the limits of quantification (S/N ≥ 10) were 4. 2 and 12 µg, respectively. The method detection limit (MDL) for SCCPs was 0. 34 ng/m3 (n = 7). The recoveries of SCCPs in air samples were in the range of 81. 9% to 94. 2%. It is demonstrated that the method is suitable for the quantitative analysis of SCCPs in air samples.
Spin Rotation of Formalism for Spin Tracking
Energy Technology Data Exchange (ETDEWEB)
Luccio,A.
2008-02-01
The problem of which coefficients are adequate to correctly represent the spin rotation in vector spin tracking for polarized proton and deuteron beams in synchrotrons is here re-examined in the light of recent discussions. The main aim of this note is to show where some previous erroneous results originated and how to code spin rotation in a tracking code. Some analysis of a recent experiment is presented that confirm the correctness of the assumptions.
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.
Spin Transport by Collective Spin Excitations
Hammel, P. Chris
We report studies of angular momentum transport in insulating materials. Our measurements reveal efficient spin pumping from high wavevector k spin waves in thin film Y3Fe5O12 (YIG): spin pumping is independent of wavevector up to k ~ 20 μm-1. Optical detection of YIG FMR by NV centers in diamond reveals a role for spin waves in this insulator-to-insulator spin transfer process. Spin transport is typically suppressed by insulating barriers, but we find that fluctuating antiferromagnetic correlations enable efficient spin transport at nm-scale thicknesses in insulating antiferromagnets, even in the absence of long-range order, and that the spin decay length increases with the strength of the antiferromagnetic correlations. This research is supported by the U.S. DOE through Grants DE-FG02-03ER46054 and DE-SC0001304, by the NSF MRSEC program through Grant No. 1420451 and by the Army Research Office through Grant W911NF0910147.
Dynamic nuclear spin polarization
Energy Technology Data Exchange (ETDEWEB)
Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)
1996-11-01
Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.
Arbitrary Spin Galilean Oscillator
Hagen, C R
2014-01-01
The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be extended successfully to the arbitrary spin S case primarily because of the unwieldiness of general spin Lorentz invariant wave equations. It is shown here using the formalism of totally symmetric multispinors that the Dirac oscillator can, however, be made to accommodate spin by incorporating it into the framework of Galilean relativity. This is done explicitly for spin zero and spin one as special cases of the arbitrary spin result. For the general case it is shown that the coefficient of the spin-orbit term has a 1/S behavior by techniques which are virtually identical to those employed in the derivation of the g-factor carried out over four decades ago.
Herniman, Julie M; Bristow, Tony W T; O'Connor, Gavin; Jarvis, Jackie; Langley, G John
2004-01-01
The use of a second electrospray nebuliser has proved to be highly successful for exact mass measurement during high-performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICRMS). Much improved accuracy and precision of mass measurement were afforded by the introduction of the internal calibration solution, thus overcoming space charge issues due to the lack of control over relative ion abundances of the species eluting from the HPLC column. Further, issues of suppression of ionisation, observed when using a T-piece method, are addressed and this simple system has significant benefits over other more elaborate approaches providing data that compares very favourably with these other approaches. The technique is robust, flexible and transferable and can be used in conjunction with HPLC, infusion or flow injection analysis (FIA) to provide constant internal calibration signals to allow routine, accurate and precise mass measurements to be recorded.
Cross, Rod
2013-01-01
Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction…
Saraji, Mohammad; Ghani, Milad
2015-10-30
A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis.
Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Maurya, Shailendra Kumar; Khan, Haider A; Bandyopadhyay, Sanghamitra; Murthy, R C
2012-05-01
A simple and rapid method to determine the cypermethrin (CYP) insecticide in rat tissues (kidney, liver and brain) and blood has been developed for the first time using low density solvent-dispersive liquid-liquid microextraction (LDS-DLLME) followed by gas chromatography-electron capture detector (GC-ECD) analysis. Initially, tissue samples containing CYP were homoginized in acetone. Subsequently, homogenate was mixed with n-hexane (extraction solvent) and the mixture was rapidly injected into water. The upper n-hexane layer was collected in a separate microtube and injected into GC-ECD for analysis. Blood samples were diluted with ultrapure water and subjected to DLLME through similar procedure. Parameters such as type and volume of disperser and extraction solvent, salting out effect and extraction time, which can affect the extraction efficiency of DLLME, were optimized. Method was validated by investigating linearity, precision, recovery, limit of detection (LOD) and quantification (LOQ). LODs in tissue were in the range of 0.043-0.314 ng mg(-1) and for blood it was 8.6 ng mL(-1) with a signal to noise ratio of 3:1. LOQs in tissue were in the range of 0.143-1.03 ng mg(-1) and for blood it was 28.3 ng mL(-1) with a signal to noise ratio of 10:1. Mean recoveries of CYP at three different concentation levels in all the matrices were found to be in the range of 81.6-103.67%. The results show that, LDS-DLLME coupled with GC-ECD offers a simple, rapid and efficient technique for extraction and determination of CYP in rat tissues and blood samples, which in turn would be useful for toxicological studies of CYP.
Inverse spin Hall effect by spin injection
Liu, S. Y.; Horing, Norman J. M.; Lei, X. L.
2007-09-01
Motivated by a recent experiment [S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176 (2006)], the authors present a quantitative microscopic theory to investigate the inverse spin-Hall effect with spin injection into aluminum considering both intrinsic and extrinsic spin-orbit couplings using the orthogonalized-plane-wave method. Their theoretical results are in good agreement with the experimental data. It is also clear that the magnitude of the anomalous Hall resistivity is mainly due to contributions from extrinsic skew scattering.
Spin supplementary conditions for spinning compact binaries
Mikóczi, Balázs
2016-01-01
We consider the different spin supplementary conditions (SSC) for a spinning compact binary with the leading-order spin-orbit (SO) interaction. The Lagrangian of the binary system can be constructed but it is acceleration-dependent in two cases of SSC. We rewrite the generalized Hamiltonian formalism proposed by Ostrogradsky and compute the conservative quantities and the dissipative part of relative motion during the gravitational radiation of each SSCs. We give the orbital elements and observed quantities of the SO dynamics, for instance the energy and the orbital angular momentum losses and waveforms and discuss their SSC dependence.
Mellado, Paula
Spin ice in magnetic pyrochlore oxides is a peculiar magnetic state. Like ordinary water ice, these materials are in apparent violation with the third law of thermodynamics, which dictates that the entropy of a system in thermal equilibrium vanishes as its temperature approaches absolute zero. In ice, a "zero-point" entropy is retained down to low temperatures thanks to a high number of low-energy positions of hydrogen ions associated with the Bernal-Fowler ice-rules. Spins in pyrochlore oxides Ho2Ti 2O7 and Dy2Ti2O7 exhibit a similar degeneracy of ground states and thus also have a sizable zero-point entropy. A recent discovery of excitations carrying magnetic charges in pyrochlore spin ice adds another interesting dimension to these magnets. This thesis is devoted to a theoretical study of a two-dimensional version of spin ice whose spins reside on kagome, a lattice of corner-sharing triangles. It covers two aspects of this frustrated classical spin system: the dynamics of artificial spin ice in a network of magnetic nanowires and the thermodynamics of crystalline spin ice. Magnetization dynamics in artificial spin ice is mediated by the emission, propagation and absorption of domain walls in magnetic nanowires. The dynamics shows signs of self-organized behavior such as avalanches. The theoretical model compares favorably to recent experiments. The thermodynamics of the microscopic version of spin ice on kagome is examined through analytical calculations and numerical simulations. The results show that, in addition to the high-temperature paramagnetic phase and the low-temperature phase with magnetic order, spin ice on kagome may have an intermediate phase with fluctuating spins and ordered magnetic charges. This work is concluded with a calculation of the entropy of kagome spin ice at zero temperature when one of the sublattices is pinned by an applied magnetic field and the system breaks up into independent spin chains, a case of dimensional reduction.
Spinning particles and higher spin field equations
Bastianelli, Fiorenzo; Corradini, Olindo; Latini, Emanuele
2015-01-01
Relativistic particles with higher spin can be described in first quantization using actions with local supersymmetry on the worldline. First, we present a brief review of these actions and their use in first quantization. In a Dirac quantization scheme the field equations emerge as Dirac constraints on the Hilbert space, and we outline how they lead to the description of higher spin fields in terms of the more standard Fronsdal-Labastida equations. Then, we describe how these actions can be extended so that the propagating particle is allowed to take different values of the spin, i.e. carry a reducible representation of the Poincar\\'e group. This way one may identify a four dimensional model that carries the same degrees of freedom of the minimal Vasiliev's interacting higher spin field theory. Extensions to massive particles and to propagation on (A)dS spaces are also briefly commented upon.
Slow spin relaxation in dipolar spin ice.
Orendac, Martin; Sedlakova, Lucia; Orendacova, Alzbeta; Vrabel, Peter; Feher, Alexander; Pajerowski, Daniel M.; Cohen, Justin D.; Meisel, Mark W.; Shirai, Masae; Bramwell, Steven T.
2009-03-01
Spin relaxation in dipolar spin ice Dy2Ti2O7 and Ho2Ti2O7 was investigated using the magnetocaloric effect and susceptibility. The magnetocaloric behavior of Dy2Ti2O7 at temperatures where the orientation of spins is governed by ``ice rules`` (T Tice) revealed thermally activated relaxation; however, the resulting temperature dependence of the relaxation time is more complicated than anticipated by a mere extrapolation of the corresponding high temperature data [1]. A susceptibility study of Ho2Ti2O7 was performed at T > Tice and in high magnetic fields, and the results suggest a slow relaxation of spins analogous to the behavior reported in a highly polarized cooperative paramagnet [2]. [1] J. Snyder et al., Phys. Rev. Lett. 91 (2003) 107201. [2] B. G. Ueland et al., Phys. Rev. Lett. 96 (2006) 027216.
Spin accumulation in the extrinsic spin Hall effect
Tse, Wang-Kong; Fabian, J.; Žutić, I.; Das Sarma, S.
2005-12-01
The drift-diffusion formalism for spin-polarized carrier transport in semiconductors is generalized to include spin-orbit coupling. The theory is applied to treat the extrinsic spin Hall effect using realistic boundary conditions. It is shown that carrier and spin-diffusion lengths are modified by the presence of spin-orbit coupling and that spin accumulation due to the extrinsic spin Hall effect is strongly and qualitatively influenced by boundary conditions. Analytical formulas for the spin-dependent carrier recombination rates and inhomogeneous spin densities and currents are presented.
Henneaux, Marc; Vasiliev, Mikhail A
2017-01-01
Symmetries play a fundamental role in physics. Non-Abelian gauge symmetries are the symmetries behind theories for massless spin-1 particles, while the reparametrization symmetry is behind Einstein's gravity theory for massless spin-2 particles. In supersymmetric theories these particles can be connected also to massless fermionic particles. Does Nature stop at spin-2 or can there also be massless higher spin theories. In the past strong indications have been given that such theories do not exist. However, in recent times ways to evade those constraints have been found and higher spin gauge theories have been constructed. With the advent of the AdS/CFT duality correspondence even stronger indications have been given that higher spin gauge theories play an important role in fundamental physics. All these issues were discussed at an international workshop in Singapore in November 2015 where the leading scientists in the field participated. This volume presents an up-to-date, detailed overview of the theories i...
2015-07-15
Progress Report (ONR Award No. N00014-14-1-0804) Quantum Spin Gyroscope August 2014-July 2015 Report Type: Annual Report Primary Contact E-mail... Quantum Spin Gyroscope Grant/Contract Number: N00014-14-1-0804 Principal Investigator Name: Paola Cappellaro Program Manager: Richard Tommy Willis...required large volumes. Our project aims at overcoming these drawbacks by developing a novel solid-state quantum spin gyro- scope associated with the
Torczynski, John R.
2000-01-01
A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.
Picosecond Spin Seebeck Effect
Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.
2017-02-01
We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal metal /Y3Fe5 O12 bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal metal /Y3Fe5 O12 interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of 108 A m-2 K-1 .
Picosecond spin Seebeck effect
Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.
2016-01-01
We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect driven by an interfacial temperature difference between itinerant electrons and magnons. The measured time-evolution of spin accumulation induced by laser-excitation indicates transfer of angular momentum across Au/Y$_3$Fe$_5$O$_{12}$ and Cu/Y$_3$Fe$_5$O$_{12}$ interfaces on a picosecond time-scale. The product of spin-mixing conductance and interfacial spin Seebeck coefficient determined is...
Wang, Yilin; Ding, Chunguang; Du, Kehe; Xiao, Yao; Wu, Caisheng; Zhang, Jinlan; Qin, Hailin; Du, Guanhua
2009-09-01
Xiao-xu-ming decoction (XXMD) prescription is a traditional Chinese prescription that has been widely used to treat theoplegia and the sequela of theoplegia. Modern pharmacological research has also indicated that the active fraction from XXMD is able to treat cardiovascular diseases and Alzheimer's disease. In the study reported here, high-performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICR-MS) was developed to identify active compounds and their metabolites after oral administration of active fraction from Xiao-xu-ming decoction to rats, using parent mass list triggered data-dependent multiple-stage mass analysis at a resolving power of 100,000 in the external calibration mode. The mass accuracies obtained for full-scan MS were within 2 ppm in most cases. Fifteen constituents were identified in the active fraction from XXMD and the biological samples of rats. The fragmentation behaviors of these constituents were summarized which would be helpful for structural characterization. The profiles of the constituents in the active fraction and biological samples of rats were obtained which provided us with much information for a better understanding of the chemical basis of the pharmacologic actions of XXMD.
Hawkes, N
1999-01-01
RAL is fostering commerical exploitation of its research and facilities in two main ways : spin-out companies exploit work done at the lab, spin-in companies work on site taking advantage of the facilities and the expertise available (1/2 page).
Bahr, Benjamin; Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy
2010-01-01
The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as the main tool. An equivalence relation we impose in the set of the operator spin foams allows to split the faces and the edges of the foams. The consistency with that relation requires introduction of the (familiar for the BF theory) face amplitude. The operator spin foam models are defined quite generally. Imposing a maximal symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with demanding consistency with splitting the edges, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on Spin(4) BF spin foam model is exactly the way we tend to view 4d quantum gravity, starting with the BC model and continuing with the EPRL or FK models. That makes...
Antiferromagnetic spin Seebeck effect.
Energy Technology Data Exchange (ETDEWEB)
Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand
2016-03-03
We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2. A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF2(110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2–80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9T) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.
Antiferromagnetic Spin Seebeck Effect
Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand
2016-03-01
We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2 . A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30 nm )/Pt (4 nm) grown by molecular beam epitaxy on a MgF2 (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2-80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9 T ) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.
Single spin magnetic resonance
Wrachtrup, Jörg; Finkler, Amit
2016-08-01
Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.
DEFF Research Database (Denmark)
Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans
1975-01-01
with increasing temperatures implies that the two-ion coupling is effectively isotropic above ∼ 150 K. We present arguments for concluding that, among the mechanisms which may introduce anisotropic two-ion couplings in the rare-earth metals, the modification of the indirect exchange interaction by the spin......The energies of spin waves propagating in the c direction of Tb have been studied by inelastic neutron scattering, as a function of a magnetic field applied along the easy and hard directions in the basal plane, and as a function of temperature. From a general spin Hamiltonian, consistent...... with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results...
Antiferromagnetic spin Seebeck Effect
Wu, SM; W. Zhang; Kc, A; Borisov, P.; Pearson, JE; Jiang, JS; Lederman, D.; Hoffmann, A.; Bhattacharya, A
2015-01-01
We report on the observation of the spin Seebeck effect in antiferromagnetic MnF_{2}. A device scale on-chip heater is deposited on a bilayer of MnF_{2} (110) (30 nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF_{2} (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF_{2} through the inverse spin Hall effect. The low temperature (2-80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop t...
Fractionalized spin-wave continuum in kagome spin liquids
Mei, Jia-Wei; Wen, Xiao-Gang
Motivated by spin-wave continuum (SWC) observed in recent neutron scattering experiments in Herbertsmithite, we use Gutzwiller-projected wave functions to study dynamic spin structure factor S (q , ω) of spin liquid states on the kagome lattice. Spin-1 excited states in spin liquids are represented by Gutzwiller-projected two-spinon excited wave functions. We investigate three different spin liquid candidates, spinon Fermi-surface spin liquid (FSL), Dirac spin liquid (DSL) and random-flux spin liquid (RSL). FSL and RSL have low energy peaks in S (q , ω) at K points in the extended magnetic Brillouin zone, in contrast to experiments where low energy peaks are found at M points. There is no obviuos contradiction between DSL and neutron scattering measurements. Besides a fractionalized spin (i.e. spin-1/2), spinons in DSL carry a fractionalized crystal momentum which is potentially detectable in SWC in the neutron scattering measurements.
Spin transport at interfaces with spin-orbit coupling: Formalism
Amin, V. P.; Stiles, M. D.
2016-09-01
We generalize magnetoelectronic circuit theory to account for spin transfer to and from the atomic lattice via interfacial spin-orbit coupling. This enables a proper treatment of spin transport at interfaces between a ferromagnet and a heavy-metal nonmagnet. This generalized approach describes spin transport in terms of drops in spin and charge accumulations across the interface (as in the standard approach), but additionally includes the responses from in-plane electric fields and offsets in spin accumulations. A key finding is that in-plane electric fields give rise to spin accumulations and spin currents that can be polarized in any direction, generalizing the Rashba-Edelstein and spin Hall effects. The spin accumulations exert torques on the magnetization at the interface when they are misaligned from the magnetization. The additional out-of-plane spin currents exert torques via the spin-transfer mechanism on the ferromagnetic layer. To account for these phenomena we also describe spin torques within the generalized circuit theory. The additional effects included in this generalized circuit theory suggest modifications in the interpretations of experiments involving spin-orbit torques, spin pumping, spin memory loss, the Rashba-Edelstein effect, and the spin Hall magnetoresistance.
Spin Hall and spin Nernst effects in graphene with intrinsic and Rashba spin-orbit interactions
Institute of Scientific and Technical Information of China (English)
Zhu Guo-Bao
2012-01-01
The spin Hall and spin Nernst effects in graphene are studied based on Green's function formalism.We calculate intrinsic contributions to spin Hall and spin Nernst conductivities in the Kane-Mele model with various structures.When both intrinsic and Rashba spin-orbit interactions are present,their interplay leads to some characteristics of the dependence of spin Hall and spin Nernst conductivities on the Fermi level.When the Rashba spin-orbit interaction is smaller than intrinsic spin-orbit coupling,a weak kink in the conductance appears.The kink disappears and a divergence appears when the Rashba spin-orbit interaction enhances.When the Rashba spin-orbit interaction approaches and is stronger than intrinsic spin-orbit coupling,the divergence becomes more obvious.
Institute of Scientific and Technical Information of China (English)
Tina Boikos
2008-01-01
@@ The alarm has just gone off. Do I really have to get up? I wonder. Originally, signing up for an early-morning spinning class seemed like a good idea; it jump-starts the day with some well-needed exercise.
Hunter, G; Hunter, Geoffrey; Schlifer, Ian
2005-01-01
The recently established existence of spherical harmonic functions, $Y_\\ell^{m}(\\theta,\\phi)$ for half-odd-integer values of $\\ell$ and $m$, allows for the introduction into quantum chemistry of explicit electron spin-coordinates; i.e. spherical polar angles $\\theta_s, \\phi_s$, that specify the orientation of the spin angular momentum vector in space. In this coordinate representation the spin angular momentum operators, $S^2, S_z$, are represented by the usual differential operators in spherical polar coordinates (commonly used for $L^2, L_z$), and their electron-spin eigenfunctions are $\\sqrt{\\sin\\theta_s} \\exp(\\pm\\phi_s/2)$. This eigenfunction representation has the pedagogical advantage over the abstract spin eigenfunctions, $\\alpha, \\beta,$ that ``integration over spin coordinates'' is a true integration (over the angles $\\theta_s, \\phi_s$). In addition they facilitate construction of many electron wavefunctions in which the electron spins are neither parallel nor antiparallel, but inclined at an interme...
SPIN Tutorial: How to Become a SPIN Doctor
Ruys, T.C.; Bosnacki, D.; Leue, S.
2002-01-01
SPIN is a model checker for the verification of software systems. SPIN uses a high level language called PROMELA to specify systems descriptions. The goal of this tutorial is to introduce novice users to both PROMELA and SPIN. The tutorial itself is divided into two parts. The BASIC SPIN part is tar
Representation of Spin Group Spin(p, q)
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The representation (&)(p, q) of spin group Spin(p, q) in any dimensional space is given by induction, and the relation between two representations, which are obtained in two kinds of inductions from Spin(p, q) to Spin(p + 1, q + 1)are studied.
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 transfer torque with spin diffusion in magnetic tunnel junctions
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.
Garcia, Y.; Ksenofontov, V.; Campbell, S. J.; Lord, J. S.; Boland, Y.; Gütlich, P.
2004-12-01
The reversible thermal spin transition which occurs in [Fe(phen)2(NCS)2] around T1/2 177 K has been investigated by muon spin relaxation (μSR) (10-280 K). The depolarisation curves are well described by two Lorentzian lines represent fast and slow components in the decay curves, with the initial asymmetry parameter of the fast component found to track the spin transition in [Fe(phen)2(NCS)2]. Comparison of zero-field and transverse field (20 Oe) μSR measurements shows that diamagnetic muonic species occur over the entire temperature range.
2013-01-01
This book covers all principal aspects of currently investigated frustrated systems, from exactly solved frustrated models to real experimental frustrated systems, going through renormalization group treatment, Monte Carlo investigation of frustrated classical Ising and vector spin models, low-dimensional systems, spin ice and quantum spin glass. The reader can - within a single book - obtain a global view of the current research development in the field of frustrated systems.This new edition is updated with recent theoretical, numerical and experimental developments in the field of frustrated
Energy Technology Data Exchange (ETDEWEB)
Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-01-15
The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
Correlation Functions and Spin
Tyc, T
2000-01-01
The k-electron correlation function of a free chaotic electron beam is derived with the spin degree of freedom taken into account. It is shown that it can be expressed with the help of correlation functions for a polarized electron beam of all orders up to k and the degree of spin polarization. The form of the correlation function suggests that if the electron beam is not highly polarized, observing multi-particle correlations should be difficult. The result can be applied also to chaotic photon beams, the degree of spin polarization being replaced by the degree of polarization.
McWeeny, Roy
2004-01-01
Originally delivered as a series of lectures, this volume systematically traces the evolution of the ""spin"" concept from its role in quantum mechanics to its assimilation into the field of chemistry. Author Roy McWeeny presents an in-depth illustration of the deductive methods of quantum theory and their application to spins in chemistry, following the path from the earliest concepts to the sophisticated physical methods employed in the investigation of molecular structure and properties. Starting with the origin and development of the spin concept, the text advances to an examination of sp
Method for estimating spin-spin interactions from magnetization curves
Tamura, Ryo; Hukushima, Koji
2017-02-01
We develop a method to estimate the spin-spin interactions in the Hamiltonian from the observed magnetization curve by machine learning based on Bayesian inference. In our method, plausible spin-spin interactions are determined by maximizing the posterior distribution, which is the conditional probability of the spin-spin interactions in the Hamiltonian for a given magnetization curve with observation noise. The conditional probability is obtained with the Markov chain Monte Carlo simulations combined with an exchange Monte Carlo method. The efficiency of our method is tested using synthetic magnetization curve data, and the results show that spin-spin interactions are estimated with a high accuracy. In particular, the relevant terms of the spin-spin interactions are successfully selected from the redundant interaction candidates by the l1 regularization in the prior distribution.
Spin pumping and inverse spin Hall effects—Insights for future spin-orbitronics (invited)
Energy Technology Data Exchange (ETDEWEB)
Zhang, Wei, E-mail: zwei@anl.gov; Jungfleisch, Matthias B.; Jiang, Wanjun; Fradin, Frank Y.; Pearson, John E.; Hoffmann, Axel, E-mail: hoffmann@anl.gov [Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States); Sklenar, Joseph; Ketterson, John B. [Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 (United States)
2015-05-07
Quantification of spin-charge interconversion has become increasingly important in the fast-developing field of spin-orbitronics. Pure spin current generated by spin pumping acts as a sensitive probe for many bulk and interface spin-orbit effects, which has been indispensable for the discovery of many promising new spin-orbit materials. We apply spin pumping and inverse spin Hall effect experiments, as a useful metrology, and study spin-orbit effects in a variety of metals and metal interfaces. We quantify the spin Hall effects in Ir and W using the conventional bilayer structures and discuss the self-induced voltage in a single layer of ferromagnetic permalloy. Finally, we extend our discussions to multilayer structures and quantitatively reveal the spin current flow in two consecutive normal metal layers.
ANALYSIS ON THE SPINNING FORCES IN FLEXIBLE SPINNING OF CONES
Institute of Scientific and Technical Information of China (English)
Xia Qinxiang; Susumu Shima
2003-01-01
Flexible spinning is a new type of spinning process where spin-forming is performed without using a mandrel. Combining shearing and rolling processes, the calculation formulas of thespinning forces in flexible spinning of cones is presented. The effects of the main processing parameters, such as gripping force G applied to the blank by the inner roller, the feed rate of rollersfand the roundness radius of outer roller ro, on the spinning forces are analyzed experimentally and theoretically.
International Spin Physics 2014 Summary
Milner, Richard G
2015-01-01
The Stern-Gerlach experiment and the origin of electron spin are described in historical context. SPIN 2014 occurs on the fortieth anniversary of the first International High Energy Spin Physics Symposium at Argonne in 1974. A brief history of the international spin conference series is presented.
On Nonlinear Higher Spin Curvature
Manvelyan, Ruben(Yerevan Physics Institute, Alikhanian Br. St. 2, Yerevan, 0036, Armenia); Mkrtchyan, Karapet; Rühl, Werner; Tovmasyan, Murad
2011-01-01
We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider in detail the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the deWit-Freedman curvature.
On nonlinear higher spin curvature
Energy Technology Data Exchange (ETDEWEB)
Manvelyan, Ruben, E-mail: manvel@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Mkrtchyan, Karapet, E-mail: karapet@yerphi.a [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Ruehl, Werner, E-mail: ruehl@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Tovmasyan, Murad, E-mail: mtovmasyan@ysu.a [Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia)
2011-05-09
We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the de Wit-Freedman curvature.
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)
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.
Directory of Open Access Journals (Sweden)
Hannelore Waska
2016-07-01
Full Text Available In recent years, electrospray-ionization mass spectrometry (ESI-MS has been increasingly used to complement the bulk determination of metal-ligand equilibria, for example via competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV. However, ESI-MS speciation analyses may be impacted by instrumental artefacts such as reduction reactions, fragmentation, and adduct formation at the ESI source, changes in the ionization efficiencies of the detected species in relation to sample matrix, and peak overlaps in response to increasing sample complexity. In our study, equilibria of the known artificial ligands citrate, ethylenediaminetetraacetic acid (EDTA, 1-nitroso-2-naphthol (NN, and salicylaldoxime (SA with iron (Fe and copper (Cu were investigated by ultra-high resolution ESI-MS, Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS, under a variety of sample matrix and ionization settings. The acquired mass spectra were compared with metal-ligand equilibrium data from the literature as well as an adapted speciation model. Overall, the mass spectra produced representative species mentioned in previous reports and predicted by the speciation calculations, such as Fe(Cit, Cu(Cit2, Fe(EDTA, Cu(EDTA, Fe(NN3, and Cu(SA2. The analyses furthermore revealed new species which had been hypothesized but not measured directly using other methods, for example ternary complexes of citrate with Fe and Cu, Cu(SA monomers, and the dimer Fe(SA2. Finally, parallel measurements of a Cu+SA calibration series and a Cu+SA+EDTA competition series indicated that FT-ICR-MS can produce linear responses and low detection limits analogous to those of ACSV. We propose that ultra-high resolution FT-ICR-MS can be used as a representative tool to study interactions of trace metals with artificial as well as natural, unknown ligands at the molecular level.
Kamga, Albert W; Behar, Fancoise; Hatcher, Patrick G
2014-05-01
Long chain fatty acids (LCFAs) are present in various natural samples and are easily detectable using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) in negative ion mode. The capability of the ESI-FT-ICR-MS for quantifying LCFAs was evaluated by performing a standard addition followed by an internal standard methodology to several kerogen extracts using n-C₂₀ fatty acid as standard. As the concentration of the standard increased, the magnitude of its peak (m/z 311.29525) increased linearly but with two separate slopes, leaving the entire mass spectra relatively unchanged, which shows evidence of reproducibility. Response factors of other LCFAs are obtained using a standard addition approach. We employed five LCFA standards (n-C₁₅, n-C₁₉, n-C₂₄, n-C₂₆, and n-C₃₀) with different carbon numbers. This allowed us to determine the response factor of all fatty acids (with carbon number between 15 and 30) by plotting the slope of each standard versus its carbon number. With the observed response factors and use of the internal standard, the concentrations of LCFAs in four kerogen extracts were measured by ESI-FT-ICR-MS and compared with those from GC-FID. The carbon number distribution obtained by ESI-FT-ICR-MS matched well the GC-FID distribution (5%–50%) with the exception of C₁₆ and C₁₈, considering that ESI-FT-ICR-MS does not differentiate between normal and branched LCFAs, whereas GC-FID does. This allows one to quantitatively compare samples with a relatively similar matrix for specific compounds such as LCFAs with no need of time-consuming derivatization procedures. Moreover, the calibration can be extended to higher carbon numbers with ESI-FT-ICR-MS, beyond the capabilities of GC/MS.
Wilson, John C.
1995-01-01
Aerodynamic plates stop litter from spinning during hoisting by helicopter. Features of proposed litter-spinning retarders include convenience of deployment and independence from ground restraint. Retarder plate(s) folded flat against bottom of litter during storage or while litter is loaded. Plate(s) held in storage position by latch that releases manually or automatically as litter is hoisted. Upon release, springs move plates into deployed position.
Spin polarizability of hyperons
Indian Academy of Sciences (India)
K B Vijaya Kumar
2014-11-01
We review the recent progress of the theoretical understanding of spin polarizabilities of the hyperon in the framework of (3) heavy baryon chiral perturbation theory (HBChPT). We present the results of a systematic leading-order calculation of hyperon Compton scattering and extract the forward spin polarizability (0) of hyperons. The results obtained for $_0$ in the case of nucleons agree with the known results of (2) HBChPT when kaon loops are not considered.
Spin transport in nanoscale spin valves and magnetic tunnel junctions
Patibandla, Sridhar
Spintronics or electronics that utilizes the spin degree of freedom of a single charge carrier (or an ensemble of charge carriers) to store, process, sense or communicate data and information is a rapidly burgeoning field in electronics. In spintronic devices, information is encoded in the spin polarization of a single carrier (or multiple carriers) and the spin(s) of these carrier(s) are manipulated for device operation. This strategy could lead to devices with low power consumption. This dissertation investigates spin transport in one dimensional and two dimensional semiconductors, with a view to applications in spintronic devices. This dissertation is arranged as follows: Chapter 1 gives a detailed introduction and necessary background to understand aspects of spin injection into a semiconductor from a spin polarized source such as a ferromagnet, and spin polarized electron transport in the semiconductor. Chapter 2 discusses the nanoporous alumina technique that is employed to fabricate nanowires and nanowire spin valves for the investigation of spin transport in 1D semiconductors. Chapter 3 investigates the spin transport in quasi one-dimensional spin valves with germanium spacer layer. These spin valves with 50nm in diameter and 1 mum length were fabricated using the porous alumina technique. Spin transport in nanoscale germanium spin valves was demonstrated and the spin relaxation lengths and the spin relaxation times were calculated. Chapter 4 discusses spin transport studies conducted in bulk high purity germanium with a view to comparing spin relaxation mechanisms in low mobility nanowires and high mobility bulk structures. Lateral spin valve with tunnel injectors were employed in this study and the spin transport measurements were conducted at various temperatures. The spin relaxation rates were measured as a function of temperature which allowed us to distinguish between two different mechanisms---D'yakonov-Perel' and Elliott-Yafet---that dominate spin
Spin Hall effect induced spin transfer through an insulator
Chen, Wei; Sigrist, Manfred; Manske, Dirk
2016-09-01
When charge current passes through a normal metal that exhibits the spin Hall effect, spin accumulates at the edge of the sample in the transverse direction. We predict that this spin accumulation, or spin voltage, enables quantum tunneling of spin through an insulator or vacuum to reach a ferromagnet without transferring charge. In a normal metal/insulator/ferromagnetic insulator trilayer (such as Pt/oxide/YIG), the quantum tunneling explains the spin-transfer torque and spin pumping that exponentially decay with the thickness of the insulator. In a normal metal/insulator/ferromagnetic metal trilayer (such as Pt/oxide/Co), the spin transfer in general does not decay monotonically with the thickness of the insulator. Combining with the spin Hall magnetoresistance, this tunneling mechanism points to the possibility of a tunneling spectroscopy that can probe the magnon density of states of a ferromagnetic insulator in an all-electrical and noninvasive manner.
Spin photonics and spin-photonic devices with dielectric metasurfaces
Liu, Yachao; Ke, Yougang; Zhou, Xinxing; Luo, Hailu; Wen, Shuangchun
2015-01-01
Dielectric metasurfaces with spatially varying birefringence and high transmission efficiency can exhibit exceptional abilities for controlling the photonic spin states. We present here some of our works on spin photonics and spin-photonic devices with metasurfaces. We develop a hybrid-order Poincare sphere to describe the evolution of spin states of wave propagation in the metasurface. Both the Berry curvature and the Pancharatnam-Berry phase on the hybrid-order Poincare sphere are demonstrated to be proportional to the variation of total angular momentum. Based on the spin-dependent property of Pancharatnam-Berry phase, we find that the photonic spin Hall effect can be observed when breaking the rotational symmetry of metasurfaces. Moreover, we show that the dielectric metasurfaces can provide great flexibility in the design of novel spin-photonic devices such as spin filter and spin-dependent beam splitter.
Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction
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.
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.
Spin Hall and Spin Nernst effect from first principles
Mertig, Ingrid
2013-03-01
Spintronics without magnetic materials is an interesting alternative to the existing spintronics applications. The spin Hall effect creates spin currents in nonmagnetic materials and avoids the problem of spin injection. Future applications of the spin Hall effect require two properties of the materials, a large spin Hall angle and a long spin diffusion length. Ab intio calculations based on density functional theory are a powerful tool to design the desired materials and to get insight into the underlying microscopic processes. We investigated the spin Hall effect in dilute alloys, in particular the intrinsic effect based on the Berry curvature as well as side-jump and the skew-scattering contributions. The results demonstrate that a large extrinsic spin Hall effect is determined by the differences between host and impurity concerning the spin-orbit interaction. It can be caused by light p scatterers as C and N in Au. A comparable large effect is observed for heavy p scatterers as Bi in Cu. An alternative way is to deposit impurities in the adatom position. Furthermore, we predict a spin current perpendicular to a temperature gradient. The phenomenon is called spin Nernst effect. The predicted spin currents can be comparably large as in the case of the spin Hall effect.
Salberger, Olof
2016-01-01
We introduce a new model of interacting spin 1/2. It describes interaction of three nearest neighbors. The Hamiltonian can be expressed in terms of Fredkin gates. The Fredkin gate (also known as the CSWAP gate) is a computational circuit suitable for reversible computing. Our construction generalizes the work of Ramis Movassagh and Peter Shor. Our model can be solved by means of Catalan combinatorics in the form of random walks on the upper half of a square lattice [Dyck walks]. Each Dyck path can be mapped to a wave function of the spins. The ground state is an equally weighted superposition of Dyck walks [instead of Motzkin walks]. We can also express it as a matrix product state. We further construct the model of interacting spins 3/2 and greater half-integer spins. The models with higher spins require coloring of Dyck walks. We construct SU(k) symmetric model [here k is the number of colors]. The leading term of the entanglement entropy is then proportional to the square root of the length of the lattice ...
Noah, M.; Vieth-Hillebrand, A.; Wilkes, H.
2012-04-01
subsequent separation into asphaltenes, aliphatic hydrocarbons, aromatic hydrocarbons, neutral nitrogen, sulphur, oxygen (NSO) compounds and carboxylic acids. The asphaltene fractions are analysed using pyrolysis-GC, all other fractions are analysed by GC-MS. Additionally Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) is used to study the chemical composition of the samples on the molecular level using different ionisation methods.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Yaping [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China); Wang, Yanmin [Department of Clinical Laboratory, Heze Municipal Hospital, Shandong (China); Guo, Shuai; Guo, Yumei; Liu, Hui [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China); Li, Zhili, E-mail: lizhili@ibms.pumc.edu.cn [Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dongdan San Tiao, Beijing 100005 (China)
2013-09-10
Graphical abstract: -- Highlights: •A novel MALDI matrix for the detection of serum free fatty acids is ammonia-treated N-(1-naphthyl) ethylenediamine dihydrochloride. •Multiple point internal standard calibration curves were constructed for nine FFAs, respectively, with excellent correlation coefficients between 0.991 and 0.999. •The MALDI-MS approach was used to rapidly differentiate the patients with and without hyperglycemia and healthy controls. -- Abstract: The blood free fatty acids (FFAs), which provide energy to the cell and act as substrates in the synthesis of fats, lipoproteins, liposaccharides, and eicosanoids, involve in a number of important physiological processes. In the present study, matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) with ammonia-treated N-(1-naphthyl) ethylenediamine dihydrochloride (ATNEDC) as a novel MALDI matrix in a negative ion mode was employed to directly quantify serum FFAs. Multiple point internal standard calibration curves between the concentration ratios of individual fatty acids to internal standard (IS, C{sub 17:0}) versus their corresponding intensity ratios were constructed for C{sub 14:0}, C{sub 16:1}, C{sub 16:0}, C{sub 18:0}, C{sub 18:1}, C{sub 18:2}, C{sub 18:3}, C{sub 20:4}, and C{sub 22:6}, respectively, in their mixture, with correlation coefficients between 0.991 and 0.999 and limits of detection (LODs) between 0.2 and 5.4 μM, along with the linear dynamic range of more than two orders of magnitude. The results indicate that the multiple point internal standard calibration could reduce the impact of ion suppression and improve quantification accuracy in the MALDI mode. The quantitative results of nine FFAs from 339 serum samples, including 161 healthy controls, 118 patients with hyperglycemia and 60 patients without hyperglycemia show that FFAs levels in hyperglycemic patient sera are significantly higher than those in healthy
Spin-Orbit Twisted Spin Waves: Group Velocity Control
Perez, F.; Baboux, F.; Ullrich, C. A.; D'Amico, I.; Vignale, G.; Karczewski, G.; Wojtowicz, T.
2016-09-01
We present a theoretical and experimental study of the interplay between spin-orbit coupling (SOC), Coulomb interaction, and motion of conduction electrons in a magnetized two-dimensional electron gas. Via a transformation of the many-body Hamiltonian we introduce the concept of spin-orbit twisted spin waves, whose energy dispersions and damping rates are obtained by a simple wave-vector shift of the spin waves without SOC. These theoretical predictions are validated by Raman scattering measurements. With optical gating of the density, we vary the strength of the SOC to alter the group velocity of the spin wave. The findings presented here differ from that of spin systems subject to the Dzyaloshinskii-Moriya interaction. Our results pave the way for novel applications in spin-wave routing devices and for the realization of lenses for spin waves.
Quantum spin transistor with a Heisenberg spin chain
Marchukov, O. V.; Volosniev, A. G.; Valiente, M.; Petrosyan, D.; Zinner, N. T.
2016-10-01
Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements.
Semiclassical spin transport in spin-orbit-coupled bands.
Culcer, Dimitrie; Sinova, Jairo; Sinitsyn, N A; Jungwirth, T; MacDonald, A H; Niu, Q
2004-07-23
Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in which the average spin is transported at the wave packet group velocity, the spin current has additional contributions from the wave packet's spin and torque dipole moments. Electric field corrections to the group velocity and carrier spin contribute to the convective term. Summing all terms we obtain an expression for the intrinsic spin-Hall conductivity of a hole-doped semiconductor, which agrees with the Kubo formula prediction for the same quantity. We discuss the calculation of spin accumulation, which illustrates the importance of the torque dipole near the boundary of the system.
Spin filter and spin valve in ferromagnetic graphene
Song, Yu; Dai, Gang
2015-06-01
We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter and a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.
Spin rectification induced by spin Hall magnetoresistance at room temperature
Wang, P.; Jiang, S. W.; Luan, Z. Z.; Zhou, L. F.; Ding, H. F.; Zhou, Y.; Tao, X. D.; Wu, D.
2016-09-01
We have experimentally and theoretically investigated the dc voltage generation in the heterostructure of Pt and yttrium iron garnet under the ferromagnetic resonance. Besides a symmetric Lorenz line shape dc voltage, an antisymmetric Lorenz line shape dc voltage is observed in field scan, which can solely originate from the spin rectification effect due to the spin Hall magnetoresistance. The angular dependence of the dc voltage is theoretically analyzed by taking into account both the spin pumping and the spin rectification effects. We find that the experimental results are in excellent agreement with the theoretical model, further identifying the spin Hall magnetoresistance origin of the spin rectification effect. Moreover, the spin pumping and the spin rectification effects are quantitatively separated by their different angular dependence at particular experimental geometry.
Quantum spin transistor with a Heisenberg spin chain
Marchukov, O. V.; Volosniev, A. G.; Valiente, M.; Petrosyan, D.; Zinner, N. T.
2016-01-01
Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements. PMID:27721438
Miller, Jan D; Hupka, Jan; Aranowski, Robert
2012-11-20
A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.
Alday, Luis F
2013-01-01
We analyze the properly normalized three-point correlator of two protected scalar operators and one higher spin twist-two operator in N=4 super Yang-Mills, in the limit of large spin j. The relevant structure constant can be extracted from the OPE of the four-point correlator of protected scalar operators. We show that crossing symmetry of the four point correlator plus a judicious guess for the perturbative structure of the three-point correlator, allow to make a prediction for the structure constant at all loops in perturbation theory, up to terms that remain finite as the spin becomes large. Furthermore, the expression for the structure constant allows to propose an expression for the all loops four-point correlator G(u,v), in the limit u,v -> 0. Our predictions are in perfect agreement with the large j expansion of results available in the literature.
Rackham, Neil
1995-01-01
True or false? In selling high-value products or services: "closing" increases your chance of success; it is essential to describe the benefits of your product or service to the customer; objection handling is an important skill; and open questions are more effective than closed questions. All false, says Neil Rackham. He and his team studied more than 35,000 sales calls made by 10,000 sales people in 23 countries over 12 years. Their findings revealed that many of the methods developed for selling low-value goods just don't work for major sales. Rackham went on to introduce his SPIN-selling method, where SPIN describes the whole selling process - Situation questions, Problem questions, Implication questions, Need-payoff questions. SPIN-selling provides you with a set of simple and practical techniques which have been tried in many of today's leading companies with dramatic improvements to their sales performance.
DEFF Research Database (Denmark)
Jensen, J.; Houmann, Jens Christian Gylden
1975-01-01
The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been...... explained by Liu as originating from the mixing of the spin states of the conduction electrons due to the spin-orbit coupling. We find that this coupling mechanism introduces interactions which violate the selection rules for a simple ferromagnet. The interactions between the magnons and phonons propagating...... in the c direction of Tb have been studied experimentally by means of inelastic neutron scattering. The magnons are coupled to both the acoustic- and optical-transverse phonons. By studying the behavior of the acoustic-optical coupling, we conclude that it is a spin-mixed-induced coupling as proposed...
Paramagnetic Spin Seebeck Effect
Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand
2015-05-01
We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20 K ), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.
Contucci, Pierluigi
2013-01-01
Presenting and developing the theory of spin glasses as a prototype for complex systems, this book is a rigorous and up-to-date introduction to their properties. The book combines a mathematical description with a physical insight of spin glass models. Topics covered include the physical origins of those models and their treatment with replica theory; mathematical properties like correlation inequalities and their use in the thermodynamic limit theory; main exact solutions of the mean field models and their probabilistic structures; and the theory of the structural properties of the spin glass phase such as stochastic stability and the overlap identities. Finally, a detailed account is given of the recent numerical simulation results and properties, including overlap equivalence, ultrametricity and decay of correlations. The book is ideal for mathematical physicists and probabilists working in disordered systems.
Ganichev, Sergey D.; Bel'Kov, Vasily V.; Tarasenko, Sergey A.; Danilov, Sergey N.; Giglberger, Stephan; Hoffmann, Christoph; Ivchenko, Eougenious L.; Weiss, Dieter; Wegscheider, Werner; Gerl, Christian; Schuh, Dieter; Stahl, Joachim; de Boeck, Jo; Borghs, Gustaaf; Prettl, Wilhelm
2006-09-01
The generation, manipulation and detection of spin-polarized electrons in low-dimensional semiconductors are at the heart of spintronics. Pure spin currents, that is, fluxes of magnetization without charge current, are quite attractive in this respect. A paradigmatic example is the spin Hall effect, where an electrical current drives a transverse spin current and causes a non-equilibrium spin accumulation observed near the sample boundary. Here we provide evidence for an another effect causing spin currents which is fundamentally different from the spin Hall effect. In contrast to the spin Hall effect, it does not require an electric current to flow: without bias the spin separation is achieved by spin-dependent scattering of electrons in media with suitable symmetry. We show, by free-carrier absorption of terahertz (THz) radiation, that spin currents flow in a wide range of temperatures. Moreover, the experimental results provide evidence that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy-relaxation processes.
Chao, Alexander W.; Courant, Ernest D.
2007-01-01
As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency Δνspin of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time τ between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference-overlap effect and a spin echo effect. This paper is to address these two effects. The interference-overlap effect occurs when Δνspin is too small, or when τ is too short, to complete the smearing process. In this case, the two resonance crossings overlap each other, and the final polarization exhibits constructive or destructive interference patterns depending on the exact value of τ. Typically, the beam’s energy spread is large and this interference-overlap effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time τ after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when τ is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving an analysis
Energy Technology Data Exchange (ETDEWEB)
Chao, Alexander W.; /SLAC; Courant, Ernest D.; /Brookhaven
2006-12-01
As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency {Delta}{nu}{sub spin} of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time {tau} between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference effect and a spin echo effect. This paper is to address these two effects. The interference effect occurs when {Delta}{nu}{sub spin} is too small, or when {tau} is too short, to complete the smearing process. In this case, the two resonance crossings interfere with each other, and the final polarization exhibits constructive or destructive patterns depending on the exact value of {tau}. Typically, the beam's energy spread is large and this interference effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time {tau} after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when {tau} is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving
2008-01-01
This book presents recent scientific achievements in the investigation of magnetization dynamics in confined magnetic systems. Introduced by Bloch as plane waves of magnetization in unconfined ferromagnets, spin waves currently play an important role in the description of very small magnetic systems ranging from microelements, which form the basis of magnetic sensors, to magnetic nano-contacts. The spin wave confinement effect was experimentally discovered in the 1990s in permalloy microstripes. The diversity of systems where this effect is observed has been steadily growing since then, and
Obukhov, Y N
2001-01-08
The gravitational effects in the relativistic quantum mechanics are investigated. The exact Foldy-Wouthuysen transformation is constructed for the Dirac particle coupled to the static spacetime metric. As a direct application, we analyze the nonrelativistic limit of the theory. The new term describing the specific spin (gravitational moment) interaction effect is recovered in the Hamiltonian. The comparison of the true gravitational coupling with the purely inertial case demonstrates that the spin relativistic effects do not violate the equivalence principle for the Dirac fermions.
Artru, X
2002-01-01
Contents : 1. Pre-history 2. Transversity versus helicity 3. The massless limit. "Cardan" and "see-saw" transformations 4. Transversity distribution delta q(x). The diquark spectator model 5. Soffer inequality 6. Tensor charge sum rule 7. t-channel analysis 8. Selection rules for delta q(x) measurements 9. Evolution with Q squared 10. Quark polarimetry. The sheared-jet (Collins) effect 11. Single-spin asymmetries in inclusive experiments 12. Quark distribution dependent on both spin and transverse momentum 13. First evidence of quark transversity
Coherent spin mixing dynamics in thermal $^{87}$Rb spin-1 and spin-2 gases
He, Xiaodong; Li, Xiaoke; Wang, Fudong; Xu, Zhifang; Wang, Dajun
2015-01-01
We study the non-equilibrium coherent spin mixing dynamics in ferromagnetic spin-1 and antiferromagnetic spin-2 thermal gases of ultracold $^{87}$Rb atoms. Long lasting spin population oscillations with magnetic field dependent resonances are observed in both cases. Our observations are well reproduced by Boltzmann equations of the Wigner distribution function. Compared to the equation of motion of spinor Bose-Einstein condensates, the only difference here is a factor of two increase in the spin-dependent interaction, which is confirmed directly in the spin-2 case by measuring the relation between the oscillation amplitude and the sample's density.
Spin current swapping and spin hall effect in disordered metals
Saidaoui, Hamed; Pauyac, Christian; Manchon, Aurelien
2015-03-01
The conversion of charge currents into spin currents via the spin Hall effect has attracted intense experimental and theoretical efforts lately, providing an efficient means to generate electric signals and manipulate the magnetization of single layers. More recently, it was proposed that spin-dependent scattering induced by spin-orbit coupled impurities also produces a so-called spin swapping, i.e. an exchange between the spin angular momentum and linear momentum of itinerant electrons. In this work, we investigate the nature of spin swapping and its interplay with extrinsic spin Hall effect and spin relaxation in finite size normal metals. We use two complementary methods based on non-equilibrium Green's function technique. The first method consists in rigorously deriving the drift-diffusion equation of the spin accumulation in the presence of spin-orbit coupled impurities from quantum kinetics using Wigner expansion. The second method is the real-space tight binding modeling of a finite system in the presence of spin-orbit coupled disorder.
Spin Caloritronic Phenomena Driven by Spin-orbit Coupling
Chen, Y.-T.
2014-01-01
In this thesis, we report several effects in spintronics and spin caloritronics related to relativistic spin-orbit coupling. In Chapter 2, we discuss the relativistic spin caloritronicHall effects in terms of a semiclassical theory for anomalous thermoelectric effects in ferromagnetic metals due to
Peskin, Michael E
1994-01-01
This is a broad-brush introduction to the theory of spin in quantum field theory, presented at the 1993 SLAC Summer Institute. It may be useful for beginning students. (text only; complete paper with figures available by anonymous ftp from preprint.slac.stanford.edu, in the directory pub/preprints/hep-ph/9405)
Urdampilleta, M.; Klyatskaya, S.; Cleuziou, J.-P.; Ruben, M.; Wernsdorfer, W.
2011-07-01
Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc2 single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.
Hamp, James; Dutton, Sian; Mourigal, Martin; Mukherjee, Paromita; Paddison, Joseph; Ong, Harapan; Castelnovo, Claudio
Spin ice materials provide a rare instance of emergent gauge symmetry and fractionalisation in three dimensions: the effective degrees of freedom of the system are emergent magnetic monopoles, and the extensively many `ice rule' ground states are those devoid of monopole excitations. Two-dimensional (kagome) analogues of spin ice have also been shown to display a similarly rich behaviour. In kagome ice however the ground-state `ice rule' condition implies the presence everywhere of magnetic charges. As temperature is lowered, an Ising transition occurs to a charge-ordered state, which can be mapped to a dimer covering of the dual honeycomb lattice. A second transition, of Kosterlitz-Thouless or three-state Potts type, occurs to a spin-ordered state at yet lower temperatures, due to small residual energy differences between charge-ordered states. Inspired by recent experimental capabilities in growing spin ice samples with selective (layered) substitution of non-magnetic ions, in this work we investigate the fate of the two ordering transitions when individual kagome layers are brought together to form a three-dimensional pyrochlore structure coupled by long range dipolar interactions. We also consider the response to substitutional disorder and applied magnetic fields.
TRANSVERSITY SINGLE SPIN ASYMMETRIES.
Energy Technology Data Exchange (ETDEWEB)
BOER,D.
2001-04-27
The theoretical aspects of two leading twist transversity single spin asymmetries, one arising from the Collins effect and one from the interference fragmentation functions, are reviewed. Issues of factorization, evolution and Sudakov factors for the relevant observables are discussed. These theoretical considerations pinpoint the most realistic scenarios towards measurements of transversity.
Antiferromagnetic spin-orbitronics
Manchon, Aurelien
2015-05-01
Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.
Polyoxometalates as spin qubits
Gaita-Ariño, A.; Aldamen, M.; Clemente-Juan, J.-M.; Coronado, E.; Lehmann, J.; Loss, D.; Stamp, P.
2008-03-01
Polyoxometalates (POMs) are discrete fragments of metal oxides, clusters of regular MOn polyhedra. POMs show a remarkable flexibility in composition, structure and charge state, and thus can be designed according to specific electric and magnetic needs. The two localized spins with S = 1/2 on the V atoms in [PMo12O40(VO)2]^q- can be coupled through the delocalized electrons of the central core. This system was recently used for a theoretical scheme involving two-qubit gates and readout: the electrical manipulation of the molecular redox potential changes the charge of the core and thus the effective magnetic exchange between the qubits. Polyoxometalates can encapsulate magnetic ions, protecting them by a diamagnetic shell of controlled geometry. A great potential of POMs as spin qubits is that they can be constructed using only even elements, such as O, W, Mo and/or Si. Thus, there is a high abundance of polyoxometalate molecules without any nuclear spin, which could result in unusually low decoherence rates. There is currently an effort involving highly anisotropic, high magnetic moment, lanthanide@polyoxometalate molecules acting as spin qubits.
Spin Injection in Indium Arsenide
Directory of Open Access Journals (Sweden)
Mark eJohnson
2015-08-01
Full Text Available In a two dimensional electron system (2DES, coherent spin precession of a ballistic spin polarized current, controlled by the Rashba spin orbit interaction, is a remarkable phenomenon that’s been observed only recently. Datta and Das predicted this precession would manifest as an oscillation in the source-drain conductance of the channel in a spin-injected field effect transistor (Spin FET. The indium arsenide single quantum well materials system has proven to be ideal for experimental confirmation. The 2DES carriers have high mobility, low sheet resistance, and high spin orbit interaction. Techniques for electrical injection and detection of spin polarized carriers were developed over the last two decades. Adapting the proposed Spin FET to the Johnson-Silsbee nonlocal geometry was a key to the first experimental demonstration of gate voltage controlled coherent spin precession. More recently, a new technique measured the oscillation as a function of channel length. This article gives an overview of the experimental phenomenology of the spin injection technique. We then review details of the application of the technique to InAs single quantum well (SQW devices. The effective magnetic field associated with Rashba spin-orbit coupling is described, and a heuristic model of coherent spin precession is presented. The two successful empirical demonstrations of the Datta Das conductance oscillation are then described and discussed.
Spin Transport in Semiconductor heterostructures
Energy Technology Data Exchange (ETDEWEB)
Domnita Catalina Marinescu
2011-02-22
The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.
Mechanical generation of spin current
Directory of Open Access Journals (Sweden)
Mamoru eMatsuo
2015-07-01
Full Text Available We focus the recent results on spin-current generation from mechanical motion such as rigid rotation and elastic deformations. Spin transport theory in accelerating frames is constructed by using the low energy expansion of the generally covariant Dirac equation. Related issues on spin-manipulation by mechanical rotation are also discussed.
Spin transport in graphene nanostructures
Guimaraes, M. H. D.; van den Berg, J. J.; Vera-Marun, I. J.; Zomer, P. J.; van Wees, B. J.
2014-01-01
Graphene is an interesting material for spintronics, showing long spin relaxation lengths even at room temperature. For future spintronic devices it is important to understand the behavior of the spins and the limitations for spin transport in structures where the dimensions are smaller than the spi
Spin-sensitive atom mirror via spin-orbit interaction
Zhou, Lu; Zheng, Ren-Fei; Zhang, Weiping
2016-11-01
Based on the spin-orbit coupling recently implemented in a neutral cold-atom gas, we propose a scheme to realize spin-dependent scattering of cold atoms. In particular we consider a matter wave packet of cold-atom gas impinging upon a step potential created by the optical light field, inside of which the atoms are subject to spin-orbit interaction. We show that the proposed system can act as a spin polarizer or spin-selective atom mirror for the incident atomic beam. The principle and the operating parameter regime of the system are carefully discussed.
Inertial effect on spin-orbit coupling and spin transport
Basu, B.; Chowdhury, Debashree
2013-08-01
We theoretically study the renormalization of inertial effects on the spin dependent transport of conduction electrons in a semiconductor by taking into account the interband mixing on the basis of k→ṡp→ perturbation theory. In our analysis, for the generation of spin current we have used the extended Drude model where the spin-orbit coupling plays an important role. We predict enhancement of the spin current resulting from the renormalized spin-orbit coupling effective in our model in cubic and non-cubic crystals. Attention has been paid to clarify the importance of gauge fields in the spin transport of this inertial system. A theoretical proposition of a perfect spin filter has been done through the Aharonov-Casher like phase corresponding to this inertial system. For a time dependent acceleration, effect of k→ ṡp→ perturbation on the spin current and spin polarization has also been addressed. Furthermore, achievement of a tunable source of polarized spin current through the non uniformity of the inertial spin-orbit coupling strength has also been discussed.
Thermal creation of a spin current by Seebeck spin tunneling
Jansen, R.; Le Breton, J. C.; Deac, A. M.; Saito, H.; Yuasa, S.
2013-09-01
The thermoelectric analog of spin-polarized tunneling, namely Seebeck spin tunneling, is a recently discovered phenomenon that arises from the spin-dependent Seebeck coefficient of a magnetic tunnel contact. In a tunnel junction with one ferromagnetic electrode and one non-magnetic electrode, a temperature difference between the two electrodes creates a spin current across the contact. Here, the basic principle and the observation of Seebeck spin tunneling are described. It is shown how it can be used to create a spin accumulation in silicon driven by a heat flow across a magnetic tunnel contact, without a charge tunnel current. The sign of the spin current depends on the direction of the heat flow, whereas its magnitude is anisotropic, i.e., dependent on the absolute orientation of the magnetization of the ferromagnet. The connection between Seebeck spin tunneling and the tunnel magneto-Seebeck effect, observed in metal magnetic tunnel junctions, is also clarified. Seebeck spin tunneling may be used to convert waste heat into useful thermal spin currents that aid or replace electrical spin current, and thereby improve the energy efficiency of spintronic devices and technologies.
Spin anisotropy and slow dynamics in spin glasses.
Bert, F; Dupuis, V; Vincent, E; Hammann, J; Bouchaud, J-P
2004-04-23
We report on an extensive study of the influence of spin anisotropy on spin glass aging dynamics. New temperature cycle experiments allow us to compare quantitatively the memory effect in four Heisenberg spin glasses with various degrees of random anisotropy and one Ising spin glass. The sharpness of the memory effect appears to decrease continuously with the spin anisotropy. Besides, the spin glass coherence length is determined by magnetic field change experiments for the first time in the Ising sample. For three representative samples, from Heisenberg to Ising spin glasses, we can consistently account for both sets of experiments (temperature cycle and magnetic field change) using a single expression for the growth of the coherence length with time.
Spin-transfer torque induced spin waves in antiferromagnetic insulators
Daniels, Matthew; Guo, Wei; Stocks, G. Malcolm; Xiao, Di; Xiao, Jiang
2015-03-01
We explore the possibility of exciting spin waves in insulating antiferromagnetic films by injecting spin current at the surface. We analyze both magnetically compensated and uncompensated interfaces. We find that the spin current induced spin-transfer torque can excite spin waves in insulating antiferromagnetic materials and that the chirality of the excited spin wave is determined by the polarization of the injected spin current. Furthermore, the presence of magnetic surface anisotropy can greatly increase the accessibility of these excitations. Supported by NSF EFRI-1433496 (M.W.D), U.S. DOE Office of Basic Energy Sciences, Materials Sciences and Engineering (D.X. & G.M.S.), Major State Basic Research Project of China and National Natural Science Foundation of China (W.G. and J.X.).
Spin-optical metamaterial route to spin-controlled photonics.
Shitrit, Nir; Yulevich, Igor; Maguid, Elhanan; Ozeri, Dror; Veksler, Dekel; Kleiner, Vladimir; Hasman, Erez
2013-05-10
Spin optics provides a route to control light, whereby the photon helicity (spin angular momentum) degeneracy is removed due to a geometric gradient onto a metasurface. The alliance of spin optics and metamaterials offers the dispersion engineering of a structured matter in a polarization helicity-dependent manner. We show that polarization-controlled optical modes of metamaterials arise where the spatial inversion symmetry is violated. The emerged spin-split dispersion of spontaneous emission originates from the spin-orbit interaction of light, generating a selection rule based on symmetry restrictions in a spin-optical metamaterial. The inversion asymmetric metasurface is obtained via anisotropic optical antenna patterns. This type of metamaterial provides a route for spin-controlled nanophotonic applications based on the design of the metasurface symmetry properties.
Spin-Currents and Spin-Pumping Forces for Spintronics
Directory of Open Access Journals (Sweden)
Henri-Jean Drouhin
2011-01-01
Full Text Available A general definition of the Spintronics concept of spin-pumping is proposed as generalized forces conjugated to the spin degrees of freedom in the framework of the theory of mesoscopic non-equilibrium thermodynamics. It is shown that at least three different kinds of spin-pumping forces and associated spin-currents can be defined in the most simple spintronics system: the Ferromagnetic/Non-Ferromagnetic metal interface. Furthermore, the generalized force associated with the ferromagnetic collective variable is also introduced on an equal footing to describe the coexistence of the spin of the conduction electrons (paramagnetic spins attached to s-band electrons and the ferromagnetic-order parameter. The dynamical coupling between these two kinds of magnetic degrees of freedom is presented and interpreted in terms of spin-transfer effects.
Spin-disordered superfluid state for spin-1 bosons with fractional spin and statistics
2002-01-01
We study a strongly correlated spin-1 Bose gas in 2D space by using the projective construction. A spin-disordered superfluid state is constructed and proposed as a candidate competing with the conventional polar condensate when interaction is antiferromagnetic. This novel state has a non-trivial topological order whose low energy excitations carry fractional spin, charge, and statistics. The spin excitations become gapless only at the edge and are described by level-1 SU(2) Kac-Moody algebra...
Energy Technology Data Exchange (ETDEWEB)
Bhattacharya, Aniruddha; Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: pkb@umich.edu [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2016-01-25
We report the measurement of diffusive electronic spin transport characteristics in an epitaxial wurtzite GaN lateral spin valve at room temperature. Hanle spin precession and non-local spin accumulation measurements have been performed with the spin valves fabricated with FeCo/MgO spin contacts. Electron spin relaxation length and spin-flip lifetime of 176 nm and 37 ps, respectively, are derived from analysis of results obtained from four-terminal Hanle spin precession measurements at 300 K. The role of dislocations and defects in bulk GaN has also been examined in the context of electronic spin relaxation dynamics.
Bhattacharya, Aniruddha; Baten, Md Zunaid; Bhattacharya, Pallab
2016-01-01
We report the measurement of diffusive electronic spin transport characteristics in an epitaxial wurtzite GaN lateral spin valve at room temperature. Hanle spin precession and non-local spin accumulation measurements have been performed with the spin valves fabricated with FeCo/MgO spin contacts. Electron spin relaxation length and spin-flip lifetime of 176 nm and 37 ps, respectively, are derived from analysis of results obtained from four-terminal Hanle spin precession measurements at 300 K. The role of dislocations and defects in bulk GaN has also been examined in the context of electronic spin relaxation dynamics.
Spin injection and spin accumulation in all-metal mesoscopic spin valves
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
Spin Structures in Magnetic Nanoparticles
DEFF Research Database (Denmark)
Mørup, Steen; Brok, Erik; Frandsen, Cathrine
2013-01-01
canting and hence a reduced magnetization. Moreover, relaxation between almost degenerate canted spin states can lead to anomalous temperature dependences of the magnetization at low temperatures. In ensembles of nanoparticles, interparticle exchange interactions can also result in spin reorientation......Spin structures in nanoparticles of ferrimagnetic materials may deviate locally in a nontrivial way from ideal collinear spin structures. For instance, magnetic frustration due to the reduced numbers of magnetic neighbors at the particle surface or around defects in the interior can lead to spin...
Thermodynamic equivalence of spin systems
Energy Technology Data Exchange (ETDEWEB)
Beltman, J.M. (Katholieke Universiteit Nijmegen (Netherlands))
1975-01-01
The thermodynamic equilibrium properties of systems composed of classical spin /sup 1///sub 2/ particles (Ising spins) are studied. Given an interaction pattern between the Ising spins the main problem is to calculate the equilibrium state(s) of the system. The point put forward here is the existence of many thermodynamical equivalent spin coordinate systems. As a consequence of this phenomenon the interaction pattern of a system may be very intricate when described with respect to one spin coordinate system whereas it may become simple with respect to another one and vice versa. A systematic investigation of this phenomenon is made. (FR)
Lorcé, Cédric
2014-01-01
The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.
Efficient spin transport through polyaniline
Mendes, J. B. S.; Alves Santos, O.; Gomes, J. P.; Assis, H. S.; Felix, J. F.; Rodríguez-Suárez, R. L.; Rezende, S. M.; Azevedo, A.
2017-01-01
By using the spin pumping process, we show that it is possible to transport a pure spin current across layers of conducting polyaniline (PANI) with several hundred nanometers sandwiched between a film of the ferrimagnetic insulator yttrium iron garnet (YIG) and a thin layer of platinum. The spin current generated by microwave-driven ferromagnetic resonance of the YIG film, injected through the YIG/PANI interface, crosses the whole PANI layer and then is injected into the Pt layer. By means of the inverse spin Hall effect in the Pt, the spin current is converted into charge current and electrically detected as a dc voltage. We measured a spin diffusion length in PANI of 590 ± 40 nm, which is very large compared with normal metals, demonstrating that PANI can be used as an efficient spin current conductor and poor charge current conductor, opening the path towards spintronics applications based in this very attractive material.
Rinaldi, C.; Bertoli, S.; Asa, M.; Baldrati, L.; Manzoni, C.; Marangoni, M.; Cerullo, G.; Bianchi, M.; Sordan, R.; Bertacco, R.; Cantoni, M.
2016-10-01
The measurement of the spin diffusion length and/or lifetime in semiconductors is a key issue for the realisation of spintronic devices, exploiting the spin degree of freedom of carriers for storing and manipulating information. In this paper, we address such parameters in germanium (0 0 1) at room temperature (RT) by three different measurement methods. Exploiting optical spin orientation in the semiconductor and spin filtering across an insulating MgO barrier, the dependence of the resistivity on the spin of photo-excited carriers in Fe/MgO/Ge spin photodiodes (spin-PDs) was electrically detected. A spin diffusion length of 0.9 ± 0.2 µm was obtained by fitting the photon energy dependence of the spin signal by a mathematical model. Electrical techniques, comprising non-local four-terminal and Hanle measurements performed on CoFeB/MgO/Ge lateral devices, led to spin diffusion lengths of 1.3 ± 0.2 µm and 1.3 ± 0.08 µm, respectively. Despite minor differences due to experimental details, the order of magnitude of the spin diffusion length is the same for the three techniques. Although standard electrical methods are the most employed in semiconductor spintronics for spin diffusion length measurements, here we demonstrate optical spin orientation as a viable alternative for the determination of the spin diffusion length in semiconductors allowing for optical spin orientation.
Spin Funneling for Enhanced Spin Injection into Ferromagnets
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.
Florakis, Ioannis; Tsulaia, Mirian
2014-01-01
We consider the Sp(2n) invariant formulation of higher spin fields on flat and curved backgrounds of constant curvature.In this formulation an infinite number of higher spin fields are packed into single scalar and spinor master fields (hyperfields) propagating on extended spaces, to be called hyperspaces, parametrized by tensorial coordinates.We show that the free field equations on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation of the scalar and spinor master fields. We compute the four--point functions on a flat hyperspace for both scalar and spinor master fields, thus extending the two-- and three--point function results of arXiv:hep-th/0312244. Then using the generalized conformal transformation we derive two--, three-- and four--point functions on AdS--like hyperspace from the corresponding correlators on the flat hyperspace.
Whitfield, J D; Biamonte, J D
2012-01-01
Designing and optimizing cost functions and energy landscapes is a problem encountered in many fields of science and engineering. These landscapes and cost functions can be embedded and annealed in experimentally controllable spin Hamiltonians. Using an approach based on group theory and symmetries, we examine the embedding of Boolean logic gates into the ground state subspace of such spin systems. We describe parameterized families of diagonal Hamiltonians and symmetry operations which preserve the ground state subspace encoding the truth tables of Boolean formulas. The ground state embeddings of adder circuits are used to illustrate how gates are combined and simplified using symmetry. Our work is relevant for experimental demonstrations of ground state embeddings found in both classical optimization as well as adiabatic quantum optimization.
Friedrich, Jan Michael
2006-01-01
Results for the spin structure of the nucleon from the COMPASS data taking periods 2002 to 2004 are presented. The quark contribution to the nucleon spin, following from a QCD fit to the new data, turns out to be significantly larger than it was derived from the previous world data. The new data favour, on the other side, a comparatively small gluon polarisation in the range $x_{g} \\approx$ 0.1. In the data taken with the deuteron target polarised transversely, the related asymmetries are found to be small on the level of accuracy reached so far, indicating a cancellation of the proton and neutron contributions. This is in agreement, for both the Collins and the Sivers asymmetry, with recent theoretical calculations. Also, a step towards the understanding of angular momentum contributions with COMPASS is taken by the evaluation of asymmetries in exclusive vector meson production.
Large Spin Perturbation Theory
Alday, Luis F
2016-01-01
We consider conformal field theories around points of large twist degeneracy. Examples of this are theories with weakly broken higher spin symmetry and perturbations around generalised free fields. At the degenerate point we introduce twist conformal blocks. These are eigenfunctions of certain quartic operators and encode the contribution, to a given four-point correlator, of the whole tower of intermediate operators with a given twist. As we perturb around the degenerate point, the twist degeneracy is lifted. In many situations this breaking is controlled by inverse powers of the spin. In such cases the twist conformal blocks can be decomposed into a sequence of functions which we systematically construct. Decomposing the four-point correlator in this basis turns crossing symmetry into an algebraic problem. Our method can be applied to a wide spectrum of conformal field theories in any number of dimensions and at any order in the breaking parameter. As an example, we compute the spectrum of various theories ...
Immirzi, Giorgio
2016-01-01
I discuss how to impose causality on spin-foam models, separating forward and backward propagation, turning a given triangulation to a 'causal set', and giving asymptotically the exponential of the Regge action, not a cosine. I show the equivalence of the prescriptions which have been proposed to achieve this. Essential to the argument is the closure condition for the 4-simplices, all made of space-like tetrahedra.
Harrington, James, Jr.
2000-01-01
Current goals are to: (1) Strengthen the science and engineering capabilities of MU-SPIN institutions in research and education via computer networks; (2) Involve and prepare minority institutions and principal investigators to successfully participate in competitive research and education processes via computer networks; and (3) Develop training and education mechanisms to support, sustain and evolve the institutional network infrastructure, thereby generating a better, prepared pool of candidates to contribute to NASA's missions.
Gukov, S G
1997-01-01
The evidently supersymmetric four-dimensional Wess-Zumino model with quenched disorder is considered at the one-loop level. The infrared fixed points of a beta-function form the moduli space $M = RP^2$ where two types of phases were found: with and without replica symmetry. While the former phase possesses only a trivial fixed point, this point become unstable in the latter phase which may be interpreted as a spin glass phase.
Lord, Michael D; Mandel, Stanley W; Wager, Jeffrey D
2002-06-01
Spinouts rarely take off; most, in fact, fall into one or more of four traps that doom them from the start. Some companies spin out ventures that are too close to the core of their businesses, in effect selling off their crown jewels. Sometimes, a parent company uses the spinout primarily to pawn off debt or expenses or to quickly raise external capital for itself. Other times, a company may try to spin out an area of its business that lacks one or more of the critical legs of a successful company--a coherent business model, say, or a solid financial base. And in many cases, parent companies can't bring themselves to sever their ownership ties and give up control of their spinouts. R.J. Reynolds, the tobacco giant, managed to avoid these traps when it successfully spun out a most unlikely venture, the pharmaceutical company Targacept. As the story illustrates, the problem with spinouts is similar to the problem of rich children. Their parents have the wherewithal to spoil them or shelter them or cling to them, but what they need is tough love and discipline--much the same discipline that characterizes successful start-ups. R.J. Reynolds recognized that it didn't know that much about the pharmaceutical business and couldn't merely try to spin out a small clone of itself. It had to treat the venture as if it were essentially starting from scratch, with a passionate entrepreneurial leader, a solid business plan, help from outside partners in the industry, and ultimately substantial venture backing. That these lessons are less obvious to executives contemplating spinning out ventures closer to their core businesses may be why so many spinouts fail.
One-dimensional spinon spin currents
Hirobe, Daichi; Sato, Masahiro; Kawamata, Takayuki; Shiomi, Yuki; Uchida, Ken-Ichi; Iguchi, Ryo; Koike, Yoji; Maekawa, Sadamichi; Saitoh, Eiji
2017-01-01
Quantum spin fluctuation in a low-dimensional or frustrated magnet breaks magnetic ordering while keeping spin correlation. Such fluctuation has been a central topic in magnetism because of its relevance to high-Tc superconductivity and topological states. However, utilizing such spin states has been quite difficult. In a one-dimensional spin-1/2 chain, a particle-like excitation called a spinon is known to be responsible for spin fluctuation in a paramagnetic state. Spinons behave as a Tomonaga-Luttinger liquid at low energy, and the spin system is often called a quantum spin chain. Here we show that a quantum spin chain generates and carries spin current, which is attributed to spinon spin current. This is demonstrated by observing an anisotropic negative spin Seebeck effect along the spin chains in Sr2CuO3. The results show that spin current can flow even in an atomic channel owing to long-range spin fluctuation.
Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect.
Chen, Wei; Sigrist, Manfred; Sinova, Jairo; Manske, Dirk
2015-11-20
In the normal-metal-ferromagnetic-insulator bilayer (such as Pt/Y_{3}Fe_{5}O_{12}) and the normal-metal-ferromagnetic-metal-oxide trilayer (such as Pt/Co/AlO_{x}) where spin injection and ejection are achieved by the spin Hall effect in the normal metal, we propose a minimal model based on quantum tunneling of spins to explain the spin-transfer torque and spin pumping caused by the spin Hall effect. The ratio of their dampinglike to fieldlike component depends on the tunneling wave function that is strongly influenced by generic material properties such as interface s-d coupling, insulating gap, and layer thickness, yet the spin relaxation plays a minor role. The quantified result renders our minimal model an inexpensive tool for searching for appropriate materials.
Bell's inequality for n spin-s particles
Cabello, A
2002-01-01
Mermin's inequality for n spin-1/2 particles and two dichotomic observables [Phys. Rev. Lett. 65, 1838 (1990)] is generalized to n spin-s particles and two maximal observables. It is shown that some multiparty multilevel Greenberger-Horne-Zeilinger states [A. Cabello, Phys. Rev. A 63, 022104 (2001)] maximally violate this inequality for any s. For a fixed n, the magnitude of violation is constant for any s, which provides a simple demonstration of the conclusion reached by Gisin and Peres for two spin-s particles in the singlet state [Phys. Lett. A 162, 15 (1992)]. For a fixed s, the violation grows exponentially with n, which provides a generalization to any s of Mermin's conclusion for n spin-1/2 particles.
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.
Diffusion equation and spin drag in spin-polarized transport
DEFF Research Database (Denmark)
Flensberg, Karsten; Jensen, Thomas Stibius; Mortensen, Asger
2001-01-01
We study the role of electron-electron interactions for spin-polarized transport using the Boltzmann equation, and derive a set of coupled transport equations. For spin-polarized transport the electron-electron interactions are important, because they tend to equilibrate the momentum of the two-spin...... species. This "spin drag" effect enhances the resistivity of the system. The enhancement is stronger the lower the dimension is, and should be measurable in, for example, a two-dimensional electron gas with ferromagnetic contacts. We also include spin-flip scattering, which has two effects......: it equilibrates the spin density imbalance and, provided it has a non-s-wave component, also a current imbalance....
Spinning particle approach to higher spin field theory
Energy Technology Data Exchange (ETDEWEB)
Corradini, Olindo, E-mail: Olindo.Corradini@bo.infn.it [Centro de Estudios en Fisica y Matematicas Basicas y Aplicadas Universidad Autonoma de Chiapas, Tuxtla Gutierrez, Chiapas (Mexico); Dipartimento di Fisica, Universita di Bologna via Irnerio 46, I-40126 Bologna (Italy); INFN, Sezione di Bologna via Irnerio 46, I-40126 Bologna (Italy)
2011-04-01
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.
Low-spin models for higher-spin Lagrangians
Francia, Dario
2011-01-01
Higher-spin theories are most commonly modelled on the example of spin 2. While this is appropriate for the description of free irreducible spin-s particles, alternative options could be equally interesting. In particular Maxwell's equations provide the effective model for maximally reducible theories of higher spins inspired by the tensionless limit of the open string. For both options, as well as for their fermionic counterparts, one can extend the analogy beyond the equations for the gauge potentials, formulating the corresponding Lagrangians in terms of higher-spin curvatures. The associated non-localities are effectively due to the elimination of auxiliary fields and do not modify the spectrum. Massive deformations of these theories are also possible, and in particular in this contribution we propose a generalisation of the Proca Lagrangian for the Maxwell-inspired geometric theories.
Quantum annealing with manufactured spins.
Johnson, M W; Amin, M H S; Gildert, S; Lanting, T; Hamze, F; Dickson, N; Harris, R; Berkley, A J; Johansson, J; Bunyk, P; Chapple, E M; Enderud, C; Hilton, J P; Karimi, K; Ladizinsky, E; Ladizinsky, N; Oh, T; Perminov, I; Rich, C; Thom, M C; Tolkacheva, E; Truncik, C J S; Uchaikin, S; Wang, J; Wilson, B; Rose, G
2011-05-12
Many interesting but practically intractable problems can be reduced to that of finding the ground state of a system of interacting spins; however, finding such a ground state remains computationally difficult. It is believed that the ground state of some naturally occurring spin systems can be effectively attained through a process called quantum annealing. If it could be harnessed, quantum annealing might improve on known methods for solving certain types of problem. However, physical investigation of quantum annealing has been largely confined to microscopic spins in condensed-matter systems. Here we use quantum annealing to find the ground state of an artificial Ising spin system comprising an array of eight superconducting flux quantum bits with programmable spin-spin couplings. We observe a clear signature of quantum annealing, distinguishable from classical thermal annealing through the temperature dependence of the time at which the system dynamics freezes. Our implementation can be configured in situ to realize a wide variety of different spin networks, each of which can be monitored as it moves towards a low-energy configuration. This programmable artificial spin network bridges the gap between the theoretical study of ideal isolated spin networks and the experimental investigation of bulk magnetic samples. Moreover, with an increased number of spins, such a system may provide a practical physical means to implement a quantum algorithm, possibly allowing more-effective approaches to solving certain classes of hard combinatorial optimization problems.
Spin-flip noise in a multiterminal spin valve
Belzig, Wolfgang; Zareyan, Malek
2004-01-01
We study shot noise and cross-correlations in a four terminal spin-valve geometry using a Boltzmann-Langevin approach. The Fano factor (shot noise to current ratio) depends on the magnetic configuration of the leads and the spin-flip processes in the normal metal. In a four-terminal geometry, spin-flip processes are particularly prominent in the cross-correlations between terminals with opposite magnetization.
CP observables with spin spin correlations in chargino production
Bartl, A.; Hohenwarter-Sodek, K.; Kernreiter, T.; Kittel, O.; Terwort, M.
2008-10-01
We study the CP-violating terms of the spin-spin correlations in chargino production ee→χ˜1±χ˜2∓, and their subsequent two-body decays into sneutrinos plus leptons. We propose novel CP-sensitive observables with the help of T-odd products of the spin-spin terms. These terms depend on the polarizations of both charginos, with one polarization perpendicular to the production plane. We identify two classes of CP-sensitive observables; one requires the reconstruction of the production plane, the other not. Our framework is the Minimal Supersymmetric Standard Model with complex parameters.
High-field spin dynamics of antiferromagnetic quantum spin chains
DEFF Research Database (Denmark)
Enderle, M.; Regnault, L.P.; Broholm, C.;
2000-01-01
The characteristic internal order of macroscopic quantum ground states in one-dimensional spin systems is usually not directly accessible, but reflected in the spin dynamics and the field dependence of the magnetic excitations. In high magnetic fields quantum phase transitions are expected. We...... present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights...
Spin-seebeck effect: a phonon driven spin distribution.
Jaworski, C M; Yang, J; Mack, S; Awschalom, D D; Myers, R C; Heremans, J P
2011-05-06
Here we report on measurements of the spin-Seebeck effect in GaMnAs over an extended temperature range alongside the thermal conductivity, specific heat, magnetization, and thermoelectric power. The amplitude of the spin-Seebeck effect in GaMnAs scales with the thermal conductivity of the GaAs substrate and the phonon-drag contribution to the thermoelectric power of the GaMnAs, demonstrating that phonons drive the spin redistribution. A phenomenological model involving phonon-magnon drag explains the spatial and temperature dependence of the measured spin distribution.
Quantum Cryptography in Spin Networks
Institute of Scientific and Technical Information of China (English)
DENG Hong-Liang; FANG Xi-Ming
2007-01-01
In this paper we propose a new scheme of long-distance quantum cryptography based on spin networks with qubits stored in electron spins of quantum dots. By conditional Faraday rotation, single photon polarization measurement, and quantum state transfer, maximal-entangled Bell states for quantum cryptography between two long-distance parties are created. Meanwhile, efficient quantum state transfer over arbitrary distances is obtained in a spin chain by a proper choice of coupling strengths and using spin memory technique improved. We also analyse the security of the scheme against the cloning-based attack which can be also implemented in spin network and discover that this spin network cloning coincides with the optimal fidelity achieved by an eavesdropper for entanglement-based cryptography.
Accurate ab initio spin densities
Boguslawski, Katharina; Legeza, Örs; Reiher, Markus
2012-01-01
We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys. 2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CA...
BRST theory for continuous spin
Bengtsson, Anders K. H.
2013-10-01
Some puzzling aspects of higher spin field theory in Minkowski space-time, such as the tracelessness constraints and the search for an underlying physical principle, are discussed. A connecting idea might be provided by the recently much researched continuous spin representations of the Poincaré group. The Wigner equations, treated as first class constraints, yields to a four-constraint BRST formulation. The resulting field theory, generalizing free higher spin field theory, is one among a set of higher spin theories that can be related to previous work on unconstrained formulations. In particular, it is conjectured that the unconstrained higher spin theory of Francia and Sagnotti is a limit of a continuous spin theory. Furthermore, a simple analysis of the constraint structure reveals a hint of a physical rationale behind the trace constraints.
BRST Theory for Continuous Spin
Bengtsson, Anders K H
2013-01-01
Some puzzling aspects of higher spin field theory in Minkowski space-time, such as the tracelessness constraints and the search for an underlying physical principle, are discussed. A connecting idea might be provided by the recently much researched continuous spin representations of the Poincar\\'e group. The Wigner equations, treated as first class constraints, yields to a four-constraint BRST formulation. The resulting field theory, generalizing free higher spin field theory, is one among a set of higher spin theories that can be related to previous work on unconstrained formulations. In particular, it is conjectured that the unconstrained higher spin theory of Francia and Sagnotti is a limit of a continuous spin theory. Furthermore, a simple analysis of the constraint structure reveals a hint of a physical rationale behind the trace constraints.
Spin currents in metallic nanostructures
Energy Technology Data Exchange (ETDEWEB)
Czeschka, Franz Dominik
2011-09-05
A pure spin current, i.e., a flow of angular momentum without accompanying net charge current, is a key ingredient in the field of spintronics. In this thesis, we experimentally investigated two different concepts for pure spin current sources suggested by theory. The first is based on a time-dependent magnetization precession which ''pumps'' a pure spin current into an adjacent non-magnetic conductor. Our experiments quantitatively corroborated important predictions expected theoretically for this approach, including the dependence of the spin current on the sample geometry and the microwave power. Even more important, we could show for the first time that the spin pumping concept is viable in a large variety of ferromagnetic materials and that it only depends on the magnetization damping. Therefore, our experiments established spin pumping as generic phenomenon and demonstrated that it is a powerful way to generate pure spin currents. The second theoretical concept is based on the conversion of charge currents into spin currents in non-magnetic nanostructures via the spin Hall effect. We experimentally investigated this approach in H-shaped, metallic nanodevices, and found that the predictions are linked to requirements not realizable with the present experimental techniques, neither in sample fabrication nor in measurement technique. Indeed, our experimental data could be consistently understood by a spin-independent transport model describing the transition from diffusive to ballistic transport. In addition, the implementation of advanced fabrication and measurement techniques allowed to discover a new non-local phenomenon, the non-local anisotropic magnetoresistance. Finally, we also studied spin-polarized supercurrents carried by spin-triplet Cooper pairs. We found that low resistance interfaces are a key requirement for further experiments in this direction. (orig.)
PHENIX Spin Program, Recent Results
Bazilevsky, A; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, Alberto; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Yu A; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S R; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Büsching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; D'Enterria, D G; Dávid, G; Delagrange, H; Denisov, A; Deshpande, Abhay A; Desmond, E J; Devismes, A; Dietzsch, O; Drapier, O; Drees, A; Drees, K A; Du Rietz, R; Durum, A; Dutta, D; Efremenko, Yu V; El-Chenawi, K F; Enokizono, A; Enyo, H; Esumi, S; Ewell, L A; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Zeev; Frantz, J E; Franz, A; Frawley, A D; Fung, S Y; Garpman, S; Ghosh, K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse-Perdekamp, M; Guryn, W; Gustafsson, Hans Åke; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G B; Kim, H J; Kistenev, E P; Kiyomichi, A; Kiyoyama, K; Klein-Bösing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V P; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A G; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Man'ko, V I; Mao, Y; Martínez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E A; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Muhlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V A; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Saitô, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sørensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarjan, P; Tepe, J D; Thomas, T L; Tojo, J; Torie, H A; Towell, R S; Tserruya, Itzhak; Tsuruoka, H; Tuli, S K; Tydesjo, H; Tyurin, N; van Hecke, H W; Velkovska, J; Velkovsky, M; Veszpremi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E A; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zhou, S J; Zolin, L S; Adler, S S; Bazilevsky, Alexander
2005-01-01
Acceleration of polarized protons in Relativistic Heavy Ion Collider (RHIC) provides unique tool to study the spin structure of the nucleon. We give a brief overview of the PHENIX program to investigate poorly known gluon and flavor decomposed see quark polarization in the proton, utilizing polarized proton collisions at RHIC. We report PHENIX first results on transverse single-spin asymmetry in pi0 and charged hadron production and longitudinal double-spin asymmetry in pi0 production at mid-rapidity.
Exploring the proton spin structure
Lorcé, Cédric
2015-01-01
Understanding the spin structure of the proton is one of the main challenges in hadronic physics. While the concepts of spin and orbital angular momentum are pretty clear in the context of non-relativistic quantum mechanics, the generalization of these concepts to quantum field theory encounters serious difficulties. It is however possible to define meaningful decompositions of the proton spin that are (in principle) measurable. We propose a summary of the present situation including recent developments and prospects of future developments.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Spinning. 23.221 Section 23.221 Aeronautics... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Spinning § 23.221 Spinning. (a...-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn...
Isoscalar spin transition in nuclei
Energy Technology Data Exchange (ETDEWEB)
Tomasi-Gustafsson, E. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France); Morlet, M.; Willis, A.; Marty, N. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Baker, F.T. [Georgia Univ., Athens, GA (United States); Beatty, D.; Edwards, G.W.R.; Glashausser, C. [Rutgers--the State Univ., Piscataway, NJ (United States); Djalali, C. [South Carolina Univ., Columbia, SC (United States). Dept. of Physics and Astronomy; Duchazeaubeneix, J.C. [Laboratoire National Saturne - Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)
1992-12-31
The study of the nuclear spin response gives a very deep insight in the magnetic properties of a nucleus. The spin-flip probability measured in inelastic scattering is a robust variable rich of information on the spin response. A study of the inelastic deuteron scattering is presented, where the isoscalar spin component of the nuclear response has been isolated for the first time. This has been possible with the 400 MeV polarized deuteron beam of Saturne and the measurement of the polarization of the outgoing deuteron with the polarimeter POMME. (author) 6 refs.; 7 figs.
DEFF Research Database (Denmark)
Bruun, Georg
2011-01-01
We examine spin diffusion in a two-component homogeneous Fermi gas in the normal phase. Using a variational approach, analytical results are presented for the spin diffusion coefficient and the related spin relaxation time as a function of temperature and interaction strength. For low temperatures......, strong correlation effects are included through the Landau parameters which we extract from Monte Carlo results. We show that the spin diffusion coefficient has a minimum for a temperature somewhat below the Fermi temperature with a value that approaches the quantum limit ~/m in the unitarity regime...
Biswas, Ayan K; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo
2015-07-17
In artificial neural networks, neurons are usually implemented with highly dissipative CMOS-based operational amplifiers. A more energy-efficient implementation is a 'spin-neuron' realized with a magneto-tunneling junction (MTJ) that is switched with a spin-polarized current (representing weighted sum of input currents) that either delivers a spin transfer torque or induces domain wall motion in the soft layer of the MTJ to mimic neuron firing. Here, we propose and analyze a different type of spin-neuron in which the soft layer of the MTJ is switched with mechanical strain generated by a voltage (representing weighted sum of input voltages) and term it straintronic spin-neuron. It dissipates orders of magnitude less energy in threshold operations than the traditional current-driven spin neuron at 0 K temperature and may even be faster. We have also studied the room-temperature firing behaviors of both types of spin neurons and find that thermal noise degrades the performance of both types, but the current-driven type is degraded much more than the straintronic type if both are optimized for maximum energy-efficiency. On the other hand, if both are designed to have the same level of thermal degradation, then the current-driven version will dissipate orders of magnitude more energy than the straintronic version. Thus, the straintronic spin-neuron is superior to current-driven spin neurons.
Yanson, I K; Naidyuk, Yu G; Fisun, V V; Konovalenko, A; Balkashin, O P; Triputen, L Yu; Korenivski, V
2007-04-01
We report an observation of spin-valve-like hysteresis within a few atomic layers at a ferromagnetic interface. We use phonon spectroscopy of nanometer-sized point contacts as an in situ probe to study the mechanism of the effect. Distinctive energy phonon peaks for contacts with dissimilar nonmagnetic outer electrodes allow localizing the observed spin switching to the top or bottom interfaces for nanometer thin ferromagnetic layers. The mechanism consistent with our data is energetically distinct atomically thin surface spin layers that can form current- or field-driven surface spin-valves within a single ferromagnetic film.
Towards spin injection into silicon
Energy Technology Data Exchange (ETDEWEB)
Dash, S.P.
2007-08-15
Si has been studied for the purpose of spin injection extensively in this thesis. Three different concepts for spin injection into Si have been addressed: (1) spin injection through a ferromagnet-Si Schottky contact, (2) spin injection using MgO tunnel barriers in between the ferromagnet and Si, and (3) spin injection from Mn-doped Si (DMS) as spin aligner. (1) FM-Si Schottky contact for spin injection: To be able to improve the interface qualities one needs to understand the atomic processes involved in the formation of silicide phases. In order to obtain more detailed insight into the formation of such phases the initial stages of growth of Co and Fe were studied in situ by HRBS with monolayer depth resolution.(2) MgO tunnel barrier for spin injection into Si: The fabrication and characterization of ultra-thin crystalline MgO tunnel barriers on Si (100) was presented. (3) Mn doped Si for spin injection: Si-based diluted magnetic semiconductor samples were prepared by doping Si with Mn by two different methods i) by Mn ion implantation and ii) by in-diffusion of Mn atoms (solid state growth). (orig.)
Spin manipulation in nanoscale superconductors.
Beckmann, D
2016-04-27
The interplay of superconductivity and magnetism in nanoscale structures has attracted considerable attention in recent years due to the exciting new physics created by the competition of these antagonistic ordering phenomena, and the prospect of exploiting this competition for superconducting spintronics devices. While much of the attention is focused on spin-polarized supercurrents created by the triplet proximity effect, the recent discovery of long range quasiparticle spin transport in high-field superconductors has rekindled interest in spin-dependent nonequilibrium properties of superconductors. In this review, the experimental situation on nonequilibrium spin injection into superconductors is discussed, and open questions and possible future directions of the field are outlined.
Spin precession in anisotropic media
Raes, B.; Cummings, A. W.; Bonell, F.; Costache, M. V.; Sierra, J. F.; Roche, S.; Valenzuela, S. O.
2017-02-01
We generalize the diffusive model for spin injection and detection in nonlocal spin structures to account for spin precession under an applied magnetic field in an anisotropic medium, for which the spin lifetime is not unique and depends on the spin orientation. We demonstrate that the spin precession (Hanle) line shape is strongly dependent on the degree of anisotropy and on the orientation of the magnetic field. In particular, we show that the anisotropy of the spin lifetime can be extracted from the measured spin signal, after dephasing in an oblique magnetic field, by using an analytical formula with a single fitting parameter. Alternatively, after identifying the fingerprints associated with the anisotropy, we propose a simple scaling of the Hanle line shapes at specific magnetic field orientations that results in a universal curve only in the isotropic case. The deviation from the universal curve can be used as a complementary means of quantifying the anisotropy by direct comparison with the solution of our generalized model. Finally, we applied our model to graphene devices and find that the spin relaxation for graphene on silicon oxide is isotropic within our experimental resolution.
Spinning particles coupled to gravity
Hojman, Sergio A
2016-01-01
Recent experimental work has determined that free falling $^{87}$Rb atoms on Earth, with vertically aligned spins, follow geodesics, thus apparently ruling out spin--gravitation interactions. It is showed that while some spinning matter models coupled to gravitation referenced to in that work seem to be ruled out by the experiment, those same experimental results confirm theoretical results derived from a Lagrangian description of spinning particles coupled to gravity constructed over forty years ago. A proposal to carry out (similar but) different experiments which will help to test the validity of the Universality of Free Fall as opposed to the correctness of the aforementioned Lagrangian theory, is presented.
Spin-Hall effect and spin-Coulomb drag in doped semiconductors
Energy Technology Data Exchange (ETDEWEB)
Hankiewicz, E M [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg, D-97074 Wuerzburg (Germany); Vignale, G [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)
2009-06-24
In this review, we describe in detail two important spin-transport phenomena: the extrinsic spin-Hall effect (coming from spin-orbit interactions between electrons and impurities) and the spin-Coulomb drag. The interplay of these two phenomena is analyzed. In particular, we discuss the influence of scattering between electrons with opposite spins on the spin current and the spin accumulation produced by the spin-Hall effect. Future challenges and open questions are briefly discussed. (topical review)
Spin Resonance Strength Calculations
Courant, E. D.
2009-08-01
In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Spin resonance strength calculations
Energy Technology Data Exchange (ETDEWEB)
Courant,E.D.
2008-10-06
In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Coherent manipulation of nuclear spins using spin injection from a half-metallic spin source
Uemura, Tetsuya; Akiho, Takafumi; Ebina, Yuya; Yamamoto, Masafumi
2016-10-01
We have developed a novel nuclear magnetic resonance (NMR) system that uses spin injection from a highly polarized spin source. Efficient spin injection into GaAs from a half-metallic spin source of Mn-rich Co2MnSi enabled an efficient dynamic nuclear polarization of Ga and As nuclei in GaAs and a sensitive detection of NMR signals. Moreover, coherent control of nuclear spins, or the Rabi oscillation between two quantum levels formed at Ga nuclei, induced by a pulsed NMR has been demonstrated at a relatively low magnetic field of ˜0.1 T. This provides a novel all-electrical solid-state NMR system with the high spatial resolution and high sensitivity needed to implement scalable nuclear-spin based qubits.
Angular dependence of spin-orbit spin-transfer torques
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.
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...
Spin-SILC: CMB polarisation component separation with spin wavelets
Rogers, Keir K.; Peiris, Hiranya V.; Leistedt, Boris; McEwen, Jason D.; Pontzen, Andrew
2016-08-01
We present Spin-SILC, a new foreground component separation method that accurately extracts the cosmic microwave background (CMB) polarisation E and B modes from raw multifrequency Stokes Q and U measurements of the microwave sky. Spin-SILC is an internal linear combination method that uses spin wavelets to analyse the spin-2 polarisation signal P = Q + iU. The wavelets are additionally directional (non-axisymmetric). This allows different morphologies of signals to be separated and therefore the cleaning algorithm is localised using an additional domain of information. The advantage of spin wavelets over standard scalar wavelets is to simultaneously and self-consistently probe scales and directions in the polarisation signal P = Q + iU and in the underlying E and B modes, therefore providing the ability to perform component separation and E-B decomposition concurrently for the first time. We test Spin-SILC on full-mission Planck simulations and data and show the capacity to correctly recover the underlying cosmological E and B modes. We also demonstrate a strong consistency of our CMB maps with those derived from existing component separation methods. Spin-SILC can be combined with the pseudo- and pure E-B spin wavelet estimators presented in a companion paper to reliably extract the cosmological signal in the presence of complicated sky cuts and noise. Therefore, it will provide a computationally-efficient method to accurately extract the CMB E and B modes for future polarisation experiments.
Unconventional spin texture in a noncentrosymmetric quantum spin Hall insulator
Mera Acosta, C.; Babilonia, O.; Abdalla, L.; Fazzio, A.
2016-07-01
We propose that the simultaneous presence of both Rashba and band inversion can lead to a Rashba-like spin splitting formed by two bands with the same in-plane helical spin texture. Because of this unconventional spin texture, the backscattering is forbidden in edge and bulk conductivity channels. We propose a noncentrosymmetric honeycomb-lattice quantum spin Hall (QSH) insulator family formed by the IV, V, and VII elements with this property. The system formed by Bi, Pb, and I atoms is mechanically stable and has both a large Rashba spin splitting of 60 meV and a large nontrivial band gap of 0.14 eV. Since the edge and the bulk states are protected by the time-reversal (TR) symmetry, contrary to what happens in most doped QSH insulators, the bulk states do not contribute to the backscattering in the electronic transport, allowing the construction of a spintronic device with less energy loss.
Harding; Contopoulos; Kazanas
1999-11-10
We examine the effects of a relativistic wind on the spin-down of a neutron star and apply our results to the study of soft gamma repeaters (SGRs), which are thought to be neutron stars with magnetic fields greater than 1014 G. We derive a spin-down formula that includes torques from both dipole radiation and episodic or continuous particle winds. We find that if SGR 1806-20 puts out a continuous particle wind of 1037 ergs s-1, then the pulsar age is consistent with that of the supernova remnant, but the derived surface dipole magnetic field is only 3x1013 G, in the range of normal radio pulsars. If instead the particle wind flows are episodic with small duty cycle, then the observed period derivatives imply magnetar-strength fields, while still allowing characteristic ages within a factor of 2 of the estimated supernova remnant age. Close monitoring of the periods of SGRs will allow us to establish or place limits on the wind duty cycle and thus the magnetic field and age of the neutron star.
Harding, A K; Kazanas, D; Harding, Alice K.; Contopoulos, Ioannis; Kazanas, Demosthenes
1999-01-01
We examine the effects of a relativistic wind on the spin down of a neutron star and apply our results to the study of Soft Gamma Repeaters (SGRs), thought to be neutron stars with magnetic fields > 10^{14} G. We derive a spin-down formula that includes torques from both dipole radiation and episodic or continuous particle winds. We find that if a continuous particle wind powers the plerionic nebula surrounding SGR1806-20, then the pulsar age is consistent with that of the supernova remnant, but the derived surface dipole magnetic field is only 3 \\times 10^{13} G, in the range of normal radio pulsars. If instead, the particle wind flows are episodic with small duty cycle, then the observed period derivatives imply magnetar-strength fields, while still allowing characteristic ages within a factor of two of the estimated supernova remnant age. Close monitoring of the periods of SGRs will be able to establish or place limits on the wind duty cycle and thus the magnetic field and age of the neutron star.
Energy Technology Data Exchange (ETDEWEB)
Lee, S.Y.
1990-06-18
The generalized snake configuration offers advantages of either shorter total snake length and smaller orbit displacement in the compact configuration or the multi-functions in the split configuration. We found that the compact configuration can save about 10% of the total length of a snake. On other hand, the spilt snake configuration can be used both as a snake and as a spin rotator for the helicity state. Using the orbit compensation dipoles, the spilt snake configuration can be located at any distance on both sides of the interaction point of a collider provided that there is no net dipole rotation between two halves of the snake. The generalized configuration is then applied to the partial snake excitation. Simple formula have been obtained to understand the behavior of the partial snake. Similar principle can also be applied to the spin rotators. We also estimate the possible snake imperfections are due to various construction errors of the dipole magnets. Accuracy of field error of better than 10{sup {minus}4} will be significant. 2 refs., 5 figs.
Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions
Dellis, A. T.; Loulakis, M.; Kominis, I. K.
2014-09-01
The physics of spin-exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise resonances overlap. The underlying physical mechanism is the two-species spin-noise correlation induced by spin-exchange collisions.
Spin transport in p-type germanium.
Rortais, F; Oyarzún, S; Bottegoni, F; Rojas-Sánchez, J-C; Laczkowski, P; Ferrari, A; Vergnaud, C; Ducruet, C; Beigné, C; Reyren, N; Marty, A; Attané, J-P; Vila, L; Gambarelli, S; Widiez, J; Ciccacci, F; Jaffrès, H; George, J-M; Jamet, M
2016-04-27
We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle θ(SHE) in Ge-p (6-7 x 10(-4) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering.
DEFF Research Database (Denmark)
Flindt, Christian; Sørensen, A. S.; Lukin, M. D.;
2007-01-01
We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control of t...
Erlingsson, S.I.
2003-01-01
The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis, stro
Decoherence in quantum spin systems
De Raedt, H; Dobrovitski, VV; Landau, DP; Lewis, SP; Schuttler, HB
2003-01-01
Computer simulations of decoherence in quantum spin systems require the solution of the time-dependent Schrodinger equation for interacting quantum spin systems over extended periods of time. We use exact diagonalization, the Chebyshev polynomial technique, four Suzuki-formula algorithms, and the sh
Some recent developments in spin glasses
Indian Academy of Sciences (India)
A P Young
2005-06-01
I give some experimental and theoretical background to spin glasses, and then discuss the nature of the phase transition in spin glasses with vector spins. Results of Monte Carlo simulations of the Heisenberg spin glass model in three dimensions are presented. A finite-size scaling analysis of the correlation length of the spins and chiralities shows that there is a single, finite-temperature transition at which both spins and chiralities order.
Modulated spin polarization in nanostructures
Energy Technology Data Exchange (ETDEWEB)
Wedekind, Sebastian; Oka, Hirofumi; Rodary, Guillemin; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)
2009-07-01
Deposition of 0.7 ML Co onto the clean Cu(111) surface at room temperature leads to the formation of triangular two atomic layers high Co islands. We study the electronic properties of these nano islands by scanning tunneling microscopy (STM) and spectroscopy (STS) at 7 K. We observe pronounced spatial modulation patterns in the local density of states (LDOS) within the islands due to electron confinement. We explore the magnetic properties of the very same islands by spin-polarized STM and STS in a magnetic field of up to 4 T. Our spin-polarized measurements in field clearly identify the parallel and anti-parallel spin orientation states of tip and sample. This enables us to measure the spatial distribution of the spin polarization within single Co islands. We find that the spin polarization is spatially modulated. Our results are discussed in view of recent theoretical predictions.
Spin Foams and Canonical Quantization
Alexandrov, Sergei; Noui, Karim
2011-01-01
This review is devoted to the analysis of the mutual consistency of the spin foam and canonical loop quantizations in three and four spacetime dimensions. In the three-dimensional context, where the two approaches are in good agreement, we show how the canonical quantization \\`a la Witten of Riemannian gravity with a positive cosmological constant is related to the Turaev-Viro spin foam model, and how the Ponzano-Regge amplitudes are related to the physical scalar product of Riemannian loop quantum gravity without cosmological constant. In the four-dimensional case, we recall a Lorentz-covariant formulation of loop quantum gravity using projected spin networks, compare it with the new spin foam models, and identify interesting relations and their pitfalls. Finally, we discuss the properties which a spin foam model is expected to possess in order to be consistent with the canonical quantization, and suggest a new model illustrating these results.
Transverse spin with coupled plasmons
Mukherjee, Samyobrata
2016-01-01
We study theoretically the transverse spin associated with the eigenmodes of a thin metal film embedded in a dielectric. We show that the transverse spin has a direct dependence on the nature and strength of the coupling leading to two distinct branches for the long- and short- range modes. We show that the short-range mode exhibits larger extraordinary spin because of its more 'structured' nature due to higher decay in propagation. In contrast to some of the earlier studies, calculations are performed retaining the full lossy character of the metal. In the limit of vanishing losses we present analytical results for the extraordinary spin for both the coupled modes. The results can have direct implications for enhancing the elusive transverse spin exploiting the coupled plasmon structures.
Stern-Gerlach Experiment with Higher Spins
Tekin, Bayram
2015-01-01
We analyze idealized sequential Stern-Gerlach experiments with higher spin particles. This analysis serves at least two purposes: The widely discussed spin-1/2 case leads to some misunderstandings which hopefully is removed by the higher spin discussion. Secondly, Wigner rotation matrices for generic spins become conceptually more transparent with this physical example. We also give compact formulas for the probabilities in terms of the angle between the sequential SG apparatuses for generic spins. We work out the spin-$1/2$, spin-$1$ and spin-$2$ cases explicitly. Since there are some confusing issues regarding the actual experiment, we also compile a "facts and fiction" section on the SG experiments.
Theory of the spin Seebeck effect.
Adachi, Hiroto; Uchida, Ken-ichi; Saitoh, Eiji; Maekawa, Sadamichi
2013-03-01
The spin Seebeck effect refers to the generation of a spin voltage caused by a temperature gradient in a ferromagnet, which enables the thermal injection of spin currents from the ferromagnet into an attached nonmagnetic metal over a macroscopic scale of several millimeters. The inverse spin Hall effect converts the injected spin current into a transverse charge voltage, thereby producing electromotive force as in the conventional charge Seebeck device. Recent theoretical and experimental efforts have shown that the magnon and phonon degrees of freedom play crucial roles in the spin Seebeck effect. In this paper, we present the theoretical basis for understanding the spin Seebeck effect and briefly discuss other thermal spin effects.
Spin Orbit Interaction Engineering for beyond Spin Transfer Torque memory
Wang, Kang L.
Spin transfer torque memory uses electron current to transfer the spin torque of electrons to switch a magnetic free layer. This talk will address an alternative approach to energy efficient non-volatile spintronics through engineering of spin orbit interaction (SOC) and the use of spin orbit torque (SOT) by the use of electric field to improve further the energy efficiency of switching. I will first discuss the engineering of interface SOC, which results in the electric field control of magnetic moment or magneto-electric (ME) effect. Magnetic memory bits based on this ME effect, referred to as magnetoelectric RAM (MeRAM), is shown to have orders of magnitude lower energy dissipation compared with spin transfer torque memory (STTRAM). Likewise, interests in spin Hall as a result of SOC have led to many advances. Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures have been shown to arise from the large SOC. The large SOC is also shown to give rise to the large SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. In particular, we will show the magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT is shown to come from the spin-momentum locked surface states of TI, which may further lead to innovative low power applications. I will also describe other related physics of SOC at the interface of anti-ferromagnetism/ferromagnetic structure and show the control exchange bias by electric field for high speed memory switching. The work was in part supported by ERFC-SHINES, NSF, ARO, TANMS, and FAME.
SpinS: Extending LTSmin with Promela through SpinJa
Berg, van der Freark; Laarman, Alfons; Heljanko, K.; Knottenbelt, W.J.
2012-01-01
We show how PROMELA can be supported by the high-performance generic model checking tools of LTSMIN. The success of the SPIN model checker has made PROMELA an important modeling language. SPINJA was created as a Java implementation of SPIN, in an effort to make the model checker easily extendible an
Spin Injection and Spin Accumulation in Permalloy–Copper Mesoscopic Spin Valves
Jedema, F.J.; Filip, A.T.; Wees, B.J. van
2002-01-01
We study the electrical injection and detection of spin currents in a lateral spin valve device, using permalloy (Py) as ferromagnetic injecting and detecting electrodes and copper (Cu) as nonmagnetic metal. Our multiterminal geometry allows us to experimentally distinguish different magnetoresistan
Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect
Jiao, H.; Bauer, G.E.W.
2013-01-01
The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE).
Directory of Open Access Journals (Sweden)
V.M. Loktev
2008-09-01
Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.
Energy Technology Data Exchange (ETDEWEB)
Prosen, Tomaz [Physics Department, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana (Slovenia)]. E-mail: prosen@fiz.uni-lj.si; Seligman, Thomas H. [Centro de Ciencias Fisicas, University of Mexico (UNAM), Cuernavaca (Mexico)]. E-mail: seligman@fis.unam.mx
2002-06-07
We define a quantity, the so-called purity fidelity, which measures the rate of dynamical irreversibility due to decoherence, observed e.g. in echo experiments, in the presence of an arbitrary small perturbation of the total (system + environment) Hamiltonian. We derive a linear response formula for the purity fidelity in terms of integrated time correlation functions of the perturbation. Our relation predicts, similar to the case of fidelity decay, that the faster the decay of purity fidelity the slower is the decay of time correlations. In particular, we find exponential decay in quantum mixing regime and faster, initially quadratic and later typically Gaussian decay in the regime of non-ergodic, e.g. integrable quantum dynamics. We illustrate our approach by an analytical calculation and numerical experiments in the Ising spin 1/2 chain kicked with tilted homogeneous magnetic field where part of the chain is interpreted as a system under observation and part as an environment. (author)
Topologically Massive Spin-1 Particles and Spin-Dependent Potentials
Ferreira, F A Gomes; Ospedal, L P R; Helayël-Neto, J A
2014-01-01
We investigate the role played by particular representations of an intermediate massive spin-1 boson in the context of spin-dependent potentials between fermionic sources in the limit of low momentum transfer. A comparison between the well-known Proca case and that of a rank-2 tensor gauge potential coupled to a 4-vector gauge field is investigated in order to extract spin- as well as velocity-dependent profiles of the interparticle potentials. Bounds on some of the coupling parameters are derived and we discuss possible applications.
Spin waves and spin instabilities in quantum plasmas
Andreev, P A
2014-01-01
We describe main ideas of method of many-particle quantum hydrodynamics allows to derive equations for description of quantum plasma evolution. We also present definitions of collective quantum variables suitable for quantum plasmas. We show that evolution of magnetic moments (spins) in quantum plasmas leads to several new branches of wave dispersion: spin-electromagnetic plasma waves and self-consistent spin waves. Propagation of neutron beams through quantum plasmas is also considered. Instabilities appearing due to interaction of magnetic moments of neutrons with plasma are described.
Confined spin wave spectra of Kagome artificial spin ice arrays
Panagiotopoulos, I.
2017-01-01
The spin wave modes of elongated magnetic islands arranged in Kagome artificial spin-ice arrays are micromagnetically simulated in the frequency regime between 3 and 16 GHz. The edge modes are more suitable in order to detect the signatures of various types of local order of the spin-ice lattice as they are much more sensitive to the magnetic configurations of neighboring elements. The spectra of arrays consisting up to 30 elements can be decomposed to those originating from local magnetic states of their vertices.
The continuous spin limit of higher spin field equations
Energy Technology Data Exchange (ETDEWEB)
Bekaert, Xavier [Institut des Hautes Etudes Scientifiques, Le Bois-Marie, 35 route de Chartres, 91440 Bures-sur-Yvette (France); Mourad, Jihad [APC, Universite Paris VII, 2 place Jussieu, 75251 Paris Cedex 05 (France); LPT, Bat. 210, Universite Paris XI, 91405 Orsay Cedex (France)
2006-01-15
We show that the Wigner equations describing the continuous spin representations can be obtained as a limit of massive higher-spin field equations. The limit involves a suitable scaling of the wave function, the mass going to zero and the spin to infinity with their product being fixed. The result allows to transform the Wigner equations to a gauge invariant Fronsdal-like form. We also give the generalisation of the Wigner equations to higher dimensions with fields belonging to arbitrary representations of the massless little group.
Coarse graining methods for spin net and spin foam models
Dittrich, Bianca; Martin-Benito, Mercedes
2011-01-01
We undertake first steps in making a class of discrete models of quantum gravity, spin foams, accessible to a large scale analysis by numerical and computational methods. In particular, we apply Migdal-Kadanoff and Tensor Network Renormalization schemes to spin net and spin foam models based on finite Abelian groups and introduce `cutoff models' to probe the fate of gauge symmetries under various such approximated renormalization group flows. For the Tensor Network Renormalization analysis, a new Gauss constraint preserving algorithm is introduced to improve numerical stability and aid physical interpretation. We also describe the fixed point structure and establish an equivalence of certain models.
Electronic structure of spin systems
Energy Technology Data Exchange (ETDEWEB)
Saha-Dasgupta, Tanusri
2016-04-15
Highlights: • We review the theoretical modeling of quantum spin systems. • We apply the Nth order muffin-tin orbital electronic structure method. • The method shows the importance of chemistry in the modeling. • CuTe{sub 2}O{sub 5} showed a 2-dimensional coupled spin dimer behavior. • Ti substituted Zn{sub 2}VO(PO{sub 4}){sub 2} showed spin gap behavior. - Abstract: Low-dimensional quantum spin systems, characterized by their unconventional magnetic properties, have attracted much attention. Synthesis of materials appropriate to various classes within these systems has made this field very attractive and a site of many activities. The experimental results like susceptibility data are fitted with the theoretical model to derive the underlying spin Hamiltonian. However, often such a fitting procedure which requires correct guess of the assumed spin Hamiltonian leads to ambiguity in deciding the representative model. In this review article, we will describe how electronic structure calculation within the framework of Nth order muffin-tin orbital (NMTO) based Wannier function technique can be utilized to identify the underlying spin model for a large number of such compounds. We will show examples from compounds belonging to vanadates and cuprates.
Quantum spin liquids: a review
Savary, Lucile; Balents, Leon
2017-01-01
Quantum spin liquids may be considered ‘quantum disordered’ ground states of spin systems, in which zero-point fluctuations are so strong that they prevent conventional magnetic long-range order. More interestingly, quantum spin liquids are prototypical examples of ground states with massive many-body entanglement, which is of a degree sufficient to render these states distinct phases of matter. Their highly entangled nature imbues quantum spin liquids with unique physical aspects, such as non-local excitations, topological properties, and more. In this review, we discuss the nature of such phases and their properties based on paradigmatic models and general arguments, and introduce theoretical technology such as gauge theory and partons, which are conveniently used in the study of quantum spin liquids. An overview is given of the different types of quantum spin liquids and the models and theories used to describe them. We also provide a guide to the current status of experiments in relation to study quantum spin liquids, and to the diverse probes used therein.
Topologically massive spin-1 particles and spin-dependent potentials
Energy Technology Data Exchange (ETDEWEB)
Ferreira, F.A.G.; Malta, P.C.; Ospedal, L.P.R.; Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro (Brazil)
2015-05-15
We investigate the role played by particular field representations of an intermediate massive spin-1 boson in the context of spin-dependent interparticle potentials between fermionic sources in the limit of low momentum transfer. The comparison between the well-known case of the Proca field and that of an exchanged spin-1 boson (with gauge-invariant mass) described by a 2-form potential mixed with a 4-vector gauge field is established in order to pursue an analysis of spin- as well as velocity-dependent profiles of the interparticle potentials. We discuss possible applications and derive an upper bound on the product of vector and pseudo-tensor coupling constants. (orig.)
CP observables with spin-spin correlations in chargino production
Energy Technology Data Exchange (ETDEWEB)
Bartl, A. [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); AHEP Group, Institut de Fisica Corpuscular-C.S.I.C., Universitat de Valencia, Edifici Instituts d' Investigacio, Apt. 22085, E-46071 Valencia (Spain); Hohenwarter-Sodek, K. [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Kernreiter, T. [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria)], E-mail: tkern@hephy.oeaw.ac.at; Kittel, O. [Physikalisches Institut der Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Terwort, M. [Institut fuer Experimentalphysik, Universitaet Hamburg, Notkestrasse 85, D-22607 Hamburg (Germany)
2008-10-11
We study the CP-violating terms of the spin-spin correlations in chargino production e{sup +}e{sup -}{yields}{chi}-tilde{sub 1}{sup {+-}}{chi}-tilde{sub 2}{sup {+-}}, and their subsequent two-body decays into sneutrinos plus leptons. We propose novel CP-sensitive observables with the help of T-odd products of the spin-spin terms. These terms depend on the polarizations of both charginos, with one polarization perpendicular to the production plane. We identify two classes of CP-sensitive observables; one requires the reconstruction of the production plane, the other not. Our framework is the Minimal Supersymmetric Standard Model with complex parameters.
CP observables with spin-spin correlations in chargino production
Bartl, Alfred; Kernreiter, T; Kittel, O; Terwort, M
2008-01-01
We study the CP-violating terms of the spin-spin correlations in chargino production e+e- -> chi^+/-_1 chi^-/+_2, and their subsequent two-body decays into sneutrinos plus leptons. We propose novel CP-sensitive observables with the help of T-odd products of the spin-spin terms. These terms depend on the polarizations of both charginos, with one polarization perpendicular to the production plane. We identify two classes of CP-sensitive observables; one requires the reconstruction of the production plane, the other not. Our framework is the Minimal Supersymmetric Standard Model with complex parameters. We also calculate the statistical significances to which our CP-sensitive observables can be determined to be non-zero.
Spin Hall effect-driven spin torque in magnetic textures
Manchon, Aurelien
2011-07-13
Current-induced spin torque and magnetization dynamics in the presence of spin Hall effect in magnetic textures is studied theoretically. The local deviation of the charge current gives rise to a current-induced spin torque of the form (1 - ΒM) × [(u 0 + αH u 0 M) ∇] M, where u0 is the direction of the injected current, H is the Hall angle and is the non-adiabaticity parameter due to spin relaxation. Since αH and ×can have a comparable order of magnitude, we show that this torque can significantly modify the current-induced dynamics of both transverse and vortex walls. © 2011 American Institute of Physics.
Spin precession in anisotropic cosmologies
Energy Technology Data Exchange (ETDEWEB)
Kamenshchik, A.Yu. [Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); L. D. Landau Institute for Theoretical Physics, Moscow (Russian Federation); INFN, Bologna (Italy); Teryaev, O.V. [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation); Lomonosov Moscow State University, Moscow (Russian Federation)
2016-05-15
We consider the precession of a Dirac particle spin in some anisotropic Bianchi universes. This effect is present already in the Bianchi-I universe. We discuss in some detail the geodesics and the spin precession for both the Kasner and the Heckmann-Schucking solutions. In the Bianchi-IX universe the spin precession acquires the chaotic character due to the stochasticity of the oscillatory approach to the cosmological singularity. The related helicity flip of fermions in the very early universe may produce the sterile particles contributing to dark matter. (orig.)
Spin squeezing and quantum correlations
Indian Academy of Sciences (India)
K S Mallesh; Swarnamala Sirsi; Mahmoud A A Sbaih; P N Deepak; G Ramachandran
2002-08-01
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin- states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin- states using 2 spinors oriented along different axes. Taking the case of = 1, we show that the `non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.
Spinning fluids in general relativity
Ray, J. R.; Smalley, L. L.
1982-01-01
General relativity field equations are employed to examine a continuous medium with internal spin. A variational principle formerly applied in the special relativity case is extended to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. An energy-momentum tensor is subsequently defined for a spinning fluid. The equations of motion of the fluid are suggested to be useful in analytical studies of galaxies, for anisotropic Bianchi universes, and for turbulent eddies.
Pairing Correlations at High Spins
Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.
The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.
Heteronuclear dipolar coupling in spin-1 NQR pulsed spin locking
Malone, M. W.; Sauer, K. L.
2014-01-01
We investigate theoretically and experimentally the role of broadening due to heteronuclear dipolar coupling in spin-1 nuclear quadrupole resonance pulsed spin locking. We find the experimental conditions where heteronuclear dipolar coupling is refocused by a standard multipulse sequence. This experimental condition allows us to extend our previously reported ability to measure the homonuclear dipolar coupling of powder samples to include substances that have heteronuclear coupling. These results are useful for designing substance detection algorithms, and for performing sample characterization.
Electrical Spin-Injection into Silicon and Spin FET
2010-02-18
MgO/silicon tunneling emitter NPN bipolar transistors . Device simulations revealed that the NDTC was the consequence of an inversion layer at...2009. He is now a research engineer at Intel Semiconductor Company. The aim of the project was to explore a tunneling emitter bipolar transistor as a...possible spin injector into silicon, and we have succeeded in that goal. The transistor has a metallic emitter that as a spin-injector will be a 1
Spin flips and quantum information for anti-parallel spins
Gisin, Nicolas
1999-01-01
We consider two different ways to encode quantum information, by parallel or anti-parallel pairs of spins. We find that there is more information in the anti-parallel ones. This purely quantum mechanical effect is due to entanglement, not of the states but occuring in the course of the measuring process. We also introduce a range of quantum information processing machines, such as spin-flip and anti-cloning.
Spin voltage generation through optical excitation of complementary spin populations
Bottegoni, Federico; Celebrano, Michele; Bollani, Monica; Biagioni, Paolo; Isella, Giovanni; Ciccacci, Franco; Finazzi, Marco
2014-08-01
By exploiting the spin degree of freedom of carriers inside electronic devices, spintronics has a huge potential for quantum computation and dissipationless interconnects. Pure spin currents in spintronic devices should be driven by a spin voltage generator, able to drive the spin distribution out of equilibrium without inducing charge currents. Ideally, such a generator should operate at room temperature, be highly integrable with existing semiconductor technology, and not interfere with other spintronic building blocks that make use of ferromagnetic materials. Here we demonstrate a device that matches these requirements by realizing the spintronic equivalent of a photovoltaic generator. Whereas a photovoltaic generator spatially separates photoexcited electrons and holes, our device exploits circularly polarized light to produce two spatially well-defined electron populations with opposite in-plane spin projections. This is achieved by modulating the phase and amplitude of the light wavefronts entering a semiconductor (germanium) with a patterned metal overlayer (platinum). The resulting light diffraction pattern features a spatially modulated chirality inside the semiconductor, which locally excites spin-polarized electrons thanks to electric dipole selection rules.
Spin-SILC: CMB polarisation component separation with spin wavelets
Rogers, Keir K; Leistedt, Boris; McEwen, Jason D; Pontzen, Andrew
2016-01-01
We present Spin-SILC, a new foreground component separation method that accurately extracts the cosmic microwave background (CMB) polarisation $E$ and $B$ modes from raw multifrequency Stokes $Q$ and $U$ measurements of the microwave sky. Spin-SILC is an internal linear combination method that uses spin wavelets to analyse the spin-2 polarisation signal $P = Q + iU$. The wavelets are additionally directional (non-axisymmetric). This allows different morphologies of signals to be separated and therefore the cleaning algorithm is localised using an additional domain of information. The advantage of spin wavelets over standard scalar wavelets is to simultaneously and self-consistently probe scales and directions in the polarisation signal $P = Q + iU$ and in the underlying $E$ and $B$ modes, therefore providing the ability to perform component separation and $E$-$B$ decomposition concurrently for the first time. We test Spin-SILC on full-mission Planck simulations and data and show the capacity to correctly reco...
Exploring the limits of spin transport efficiency for spin ejection in spin photodiodes
Simon, K. P.; Belkadi, A.; Isakovic, A. F.
2012-02-01
We examine several factors that affect the efficiency of the transport of optically excited, spin-polarized carriers in ferromagnet-semiconductor heterostructures. The process of optical excitation leads to the creation of the population of spin carriers in a III-V semiconductor [1], which faces a number of obstacles on its way out of the semiconductor. This poster addresses a hierarchy of problems that need to be addressed in order to improve the efficiency of spin ejection, with the goal of bringing it up to the efficiency level of the opposite process, the spin injection. Our approach is based on modeling the existing spin ejection data, in order to understand several spin relaxation processes and the transport across the interface between a semiconductor and a ferromagnet or other metal. Our results are based in part on Schokley-Queisser [2] approach for photodiodes efficiency. Our investigation shows that there is a considerable space for improvement of spin ejection transport efficiency, which opens up possibility of designing novel spintronics devices. [4pt] [1] A. F. Isakovic, D. M. Carr, J. Strand, et al., Phys. Rev. B 64 161304.[0pt] [2] W. Schokley, H. J. Queisser, J. Appl. Phys. 32 (3), 510.
Squeezing of Collective Excitations in Spin Ensembles
DEFF Research Database (Denmark)
Kraglund Andersen, Christian; Mølmer, Klaus
2012-01-01
We analyse the possibility to create two-mode spin squeezed states of two separate spin ensembles by inverting the spins in one ensemble and allowing spin exchange between the ensembles via a near resonant cavity field. We investigate the dynamics of the system using a combination of numerical an...
RESEARCH PLAN FOR SPIN PHYSICS AT RHIC.
Energy Technology Data Exchange (ETDEWEB)
AIDALA, C.; BUNCE, G.; ET AL.
2005-02-01
In this report we present the research plan for the RHIC spin program. The report covers (1) the science of the RHIC spin program in a world-wide context; (2) the collider performance requirements for the RHIC spin program; (3) the detector upgrades required, including timelines; (4) time evolution of the spin program.
Multichannel Exchange-Scattering Spin Polarimetry.
Ji, Fuhao; Shi, Tan; Ye, Mao; Wan, Weishi; Liu, Zhen; Wang, Jiajia; Xu, Tao; Qiao, Shan
2016-04-29
Electron spin plays important roles in determining the physical and chemical properties of matter. However, measurements of electron spin are of poor quality, impeding the development of material sciences, because the spin polarimeter has a low efficiency. Here, we show an imaging-type exchange-scattering spin polarimeter with 6786 channels and an 8.5×10^{-3} single channel efficiency. As a demonstration, the fine spin structure of the electronic states in bismuth (111) is investigated, for which strong Rashba-type spin splitting behavior is seen in both the bulk and surface states. This improvement paves the way to study novel spin related phenomena with unprecedented accuracy.
Spin transport in half-metallic ferromagnets
Ohnuma, Y.; Matsuo, M.; Maekawa, S.
2016-11-01
We theoretically investigate spin transport in half-metallic ferromagnets at finite temperatures. The side-jump and skew-scattering contributions to spin Hall conductivity are derived using the Kubo formula. The electron-magnon interaction causes a finite density of states in the energy gap of the minority-spin band and induces spin Hall conductivity. We show that spin Hall conductivity is proportional to T3 /2, with T being temperature, and is sensitive to T . We propose that spin Hall conductivity may be a tool to study the minority-spin state.
Spin gap in a spiral staircase model
Energy Technology Data Exchange (ETDEWEB)
Kiselev, M.N. [Institut fuer Theoretische Physik und Astrophysik, Wuerzburg Universitaet, Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: kiselev@physik.uni-wuerzburg.de; Aristov, D.N. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Kikoin, K. [Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)
2005-04-30
We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden symmetries. We introduce a new class of Hamiltonians for description of spin staircases-the spin systems intermediate between 2-leg ladders and S=1 spin chains. The spin exchange anisotropy along legs is described by the angle of spiral twist. The properties of a special case of spin rotator chain (SRC) corresponding to a flat 1-leg ladder is considered by means of fermionization approach based on Jordan-Wigner transformation. The influence of dynamical hidden symmetries on the scaling properties of the spin gap is discussed.
Colloquium: Persistent spin textures in semiconductor nanostructures
Schliemann, John
2017-01-01
Device concepts in semiconductor spintronics make long spin lifetimes desirable, and the requirements put on spin control by proposals for quantum information processing are even more demanding. Unfortunately, due to spin-orbit coupling electron spins in semiconductors are generically subject to rather fast decoherence. In two-dimensional quantum wells made of zinc-blende semiconductors, however, the spin-orbit interaction can be engineered to produce persistent spin structures with extraordinarily long spin lifetimes even in the presence of disorder and imperfections. Experimental and theoretical developments on this subject for both n -doped and p -doped structures are reviewed and possible device applications are discussed.
Babichev, Eugeny; Raidal, Martti; Schmidt-May, Angnis; Urban, Federico; Veermäe, Hardi; von Strauss, Mikael
2016-01-01
We provide further details on a recent proposal addressing the nature of the dark sectors in cosmology and demonstrate that all current observations related to Dark Matter can be explained by the presence of a heavy spin-2 particle. Massive spin-2 fields and their gravitational interactions are uniquely described by ghost-free bimetric theory, which is a minimal and natural extension of General Relativity. In this setup, the largeness of the physical Planck mass is naturally related to extremely weak couplings of the heavy spin-2 field to baryonic matter and therefore explains the absence of signals in experiments dedicated to Dark Matter searches. It also ensures the phenomenological viability of our model as we confirm by comparing it with cosmological and local tests of gravity. At the same time, the spin-2 field possesses standard gravitational interactions and it decays universally into all Standard Model fields but not into massless gravitons. Matching the measured DM abundance together with the require...
Baillie, C F; Johnston, D A; Plechác, P
1995-01-01
In a recent paper we found strong evidence from simulations that the Ising antiferromagnet on ``thin'' random graphs - Feynman diagrams - displayed a mean-field spin glass transition. The intrinsic interest of considering such random graphs is that they give mean field results without long range interactions or the drawbacks, arising from boundary problems, of the Bethe lattice. In this paper we reprise the saddle point calculations for the Ising and Potts ferromagnet, antiferromagnet and spin glass on Feynman diagrams. We use standard results from bifurcation theory that enable us to treat an arbitrary number of replicas and any quenched bond distribution. We note the agreement between the ferromagnetic and spin glass transition temperatures thus calculated and those derived by analogy with the Bethe lattice, or in previous replica calculations. We then investigate numerically spin glasses with a plus or minus J bond distribution fo rthe Ising and Q=3,3,10,50 state Potts models, paying particular attention t...
Experimenting with a Spinning Disk
Cross, Rod
2015-01-01
Almost everyone will have observed a spinning coin fall to a shuddering stop. How and why does it do that? Several experiments are described, suitable for a student project, to help motivate an understanding of the rotational dynamics involved.
Magnetoelectric control of spin currents
Gómez, J. E.; Vargas, J. M.; Avilés-Félix, L.; Butera, A.
2016-06-01
The ability to control the spin current injection has been explored on a hybrid magnetoelectric system consisting of a (011)-cut ferroelectric lead magnesium niobate-lead titanate (PMNT) single crystal, a ferromagnetic FePt alloy, and a metallic Pt. With this PMNT/FePt/Pt structure we have been able to control the magnetic field position or the microwave excitation frequency at which the spin pumping phenomenon between FePt and Pt occurs. We demonstrate that the magnetoelectric heterostructure operating in the L-T (longitudinal magnetized-transverse polarized) mode couples the PMNT crystal to the magnetostrictive FePt/Pt bilayer, displaying a strong magnetoelectric coefficient of ˜140 Oe cm kV-1. Our results show that this mechanism can be effectively exploited as a tunable spin current intensity emitter and open the possibility to create an oscillating or a bistable switch to effectively manipulate spin currents.
Monsma, Douwe Johannes
1998-01-01
High density magnetic recording, magnetic random access memories, displacement and current detection, contactless switching and electronic compass applications all require magnetic field sensors with unprecedented sensitivity. The spin-valve effect (giant magnetoresistance) found in 1988 in magnetic
Proton spin: A topological invariant
Tiwari, S. C.
2016-11-01
Proton spin problem is given a new perspective with the proposition that spin is a topological invariant represented by a de Rham 3-period. The idea is developed generalizing Finkelstein-Rubinstein theory for Skyrmions/kinks to topological defects, and using non-Abelian de Rham theorems. Two kinds of de Rham theorems are discussed applicable to matrix-valued differential forms, and traces. Physical and mathematical interpretations of de Rham periods are presented. It is suggested that Wilson lines and loop operators probe the local properties of the topology, and spin as a topological invariant in pDIS measurements could appear with any value from 0 to ℏ 2, i.e. proton spin decomposition has no meaning in this approach.
Spintronics: Silicon takes a spin
Jansen, Ron
2007-01-01
An efficient way to transport electron spins from a ferromagnet into silicon essentially makes silicon magnetic, and provides an exciting step towards integration of magnetism and mainstream semiconductor electronics.
Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect
Jiao, HuJun; Bauer, Gerrit E. W.
2013-05-01
The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE). Here we compute ac ISHE voltages much larger than the dc signals for various material combinations and discuss optimal conditions to observe the effect. The backflow of spin is shown to be essential to distill parameters from measured ISHE voltages for both dc and ac configurations.
Spin Hall effect by surface roughness
Zhou, Lingjun
2015-01-08
The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.
Analytic definition of spin structure
Avetisyan, Zhirayr; Saveliev, Nikolai; Vassiliev, Dmitri
2016-01-01
We work on a parallelizable time-orientable Lorentzian 4-manifold and prove that in this case the notion of spin structure can be equivalently defined in a purely analytic fashion. Our analytic definition relies on the use of the concept of a non-degenerate two-by-two formally self-adjoint first order linear differential operator and gauge transformations of such operators. We also give an analytic definition of spin structure for the 3-dimensional Riemannian case.
Spin caloritronics, origin and outlook
Yu, Haiming; Brechet, Sylvain D.; Ansermet, Jean-Philippe
2017-03-01
Spin caloritronics refers to research efforts in spintronics when a heat current plays a role. In this review, we start out by reviewing the predictions that can be drawn from the thermodynamics of irreversible processes. This serves as a conceptual framework in which to analyze the interplay of charge, spin and heat transport. This formalism predicts tensorial relations between vectorial quantities such as currents and gradients of chemical potentials or of temperature. Transverse effects such as the Nernst or Hall effects are predicted on the basis that these tensors can include an anti-symmetric contribution, which can be written with a vectorial cross-product. The local symmetry of the system may determine the direction of the vector defining such transverse effects, such as the surface of an isotropic medium. By including magnetization as state field in the thermodynamic description, spin currents appear naturally from the continuity equation for the magnetization, and dissipative spin torques are derived, which are charge-driven or heat-driven. Thermodynamics does not give the strength of these effects, but may provide relationships between them. Based on this framework, the review proceeds by showing how these effects have been observed in various systems. Spintronics has become a vast field of research, and the experiments highlighted in this review pertain only to heat effects on transport and magnetization dynamics, such as magneto-thermoelectric power, or the spin-dependence of the Seebeck effect, the spin-dependence of the Peltier effect, the spin Seebeck effect, the magnetic Seebeck effect, or the Nernst effect. The review concludes by pointing out predicted effects that are yet to be verified experimentally, and in what novel materials the standard thermal spin effects could be investigated.
Random Fields and Spin Glasses
De Dominicis, Cirano; Giardina, Irene
2010-06-01
1. A brief introduction; 2. The Random Field Ising model; 3. The dynamical approach; 4. The p=2 spherical model; 5. Mean field spin glasses: one-step RSB; 6. The Sherrington-Kirkpatrick model; 7. Mean field via TAP equations; 8. Spin glass above D=6; 9. Propagators, mostly replicon; 10. Ward-Takahashi identities and Goldstone modes; 11. Alternative approaches and conclusions; Appendices; Index.
Measurement of Spin of Projectiles
Directory of Open Access Journals (Sweden)
S. R. Verma
1989-01-01
Full Text Available Hitherto the spin of the projectile has been measured with the help of spin loop method (for magnetised projectiles and Multishot Ballistic Synchro method (for magnetised and non-magnetised projectiles. This paper discusses the method of measurement of spinwith a single ballistic synchro picture; the advantage of this method is that it dispenses with elaborate and precise optical alignment, required for Multishot Ballistic Synchro method.
Spin coherence time analytical estimations
Orlov, Yuri
2015-01-01
Section I presents a variety of analytical estimations related to spin coherence time (SCT) in a purely electric frozen-spin ring. The main result is that, in the case of m > 0 and vertical oscillations only, the kinetic energy equilibrium shift equals zero, that is, SCT does not depend on these oscillations. Section II contains additional information on this case concerning terminology, electric field definition and vertical oscillations.
Spin photocurrents in quantum wells
Ganichev, S D
2003-01-01
Spin photocurrents generated by homogeneous optical excitation with circularly polarized radiation in quantum wells (QWs) are reviewed. The absorption of circularly polarized light results in optical spin orientation due to the transfer of the angular momentum of photons to electrons of a two-dimensional electron gas. It is shown that in QWs belonging to one of the gyrotropic crystal classes a non-equilibrium spin polarization of uniformly distributed electrons causes a directed motion of electrons in the plane of the QW. A characteristic feature of this electric current, which occurs in unbiased samples, is that it reverses its direction upon changing the radiation helicity from left-handed to right-handed and vice versa. Two microscopic mechanisms are responsible for the occurrence of an electric current linked to a uniform spin polarization in a QW: the spin polarization-induced circular photogalvanic effect and the spin-galvanic effect. In both effects the current flow is driven by an asymmetric distribut...
Experimental Realization of a Quantum Spin Pump
DEFF Research Database (Denmark)
Watson, Susan; Potok, R.; M. Marcus, C.;
2003-01-01
We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin......-dependent by the application of an in-plane Zeeman field. Spin currents are measured by placing the pump in a focusing geometry with a spin-selective collector....
Spin selective filtering of polariton condensate flow
Energy Technology Data Exchange (ETDEWEB)
Gao, T. [FORTH-IESL, P.O. Box 1385, 71110 Heraklion, Crete (Greece); Department of Materials Science and Technology, University of Crete, 71003 Heraklion, Crete (Greece); Antón, C.; Martín, M. D. [Departamento de Física de Materiales, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Instituto de Ciencia de Materiales “Nicolás Cabrera,” Universidad Autónoma de Madrid, Madrid 28049 (Spain); Liew, T. C. H. [School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Hatzopoulos, Z. [FORTH-IESL, P.O. Box 1385, 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, 71003 Heraklion, Crete (Greece); Viña, L. [Departamento de Física de Materiales, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Instituto de Ciencia de Materiales “Nicolás Cabrera,” Universidad Autónoma de Madrid, Madrid 28049 (Spain); Instituto de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Eldridge, P. S., E-mail: eldridge@udel.edu [FORTH-IESL, P.O. Box 1385, 71110 Heraklion, Crete (Greece); Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (United States); Savvidis, P. G., E-mail: psav@materials.uoc.gr [FORTH-IESL, P.O. Box 1385, 71110 Heraklion, Crete (Greece); Department of Materials Science and Technology, University of Crete, 71003 Heraklion, Crete (Greece); Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)
2015-07-06
Spin-selective spatial filtering of propagating polariton condensates, using a controllable spin-dependent gating barrier, in a one-dimensional semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization.
Quantum spin transport in semiconductor nanostructures
Energy Technology Data Exchange (ETDEWEB)
Schindler, Christoph
2012-05-15
In this work, we study and quantitatively predict the quantum spin Hall effect, the spin-orbit interaction induced intrinsic spin-Hall effect, spin-orbit induced magnetizations, and spin-polarized electric currents in nanostructured two-dimensional electron or hole gases with and without the presence of magnetic fields. We propose concrete device geometries for the generation, detection, and manipulation of spin polarization and spin-polarized currents. To this end a novel multi-band quantum transport theory, that we termed the multi-scattering Buettiker probe model, is developed. The method treats quantum interference and coherence in open quantum devices on the same footing as incoherent scattering and incorporates inhomogeneous magnetic fields in a gauge-invariant and nonperturbative manner. The spin-orbit interaction parameters that control effects such as band energy spin splittings, g-factors, and spin relaxations are calculated microscopically in terms of an atomistic relativistic tight-binding model. We calculate the transverse electron focusing in external magnetic and electric fields. We have performed detailed studies of the intrinsic spin-Hall effect and its inverse effect in various material systems and geometries. We find a geometry dependent threshold value for the spin-orbit interaction for the inverse intrinsic spin-Hall effect that cannot be met by n-type GaAs structures. We propose geometries that spin polarize electric current in zero magnetic field and analyze the out-of-plane spin polarization by all electrical means. We predict unexpectedly large spin-orbit induced spin-polarization effects in zero magnetic fields that are caused by resonant enhancements of the spin-orbit interaction in specially band engineered and geometrically designed p-type nanostructures. We propose a concrete realization of a spin transistor in HgTe quantum wells, that employs the helical edge channel in the quantum spin Hall effect.
Nonhydrodynamic spin transport in superfluid 3He
Bunkov, Yu. M.; Dmitriev, V. V.; Markelov, A. V.; Mukharskii, Yu. M.; Einzel, D.
1990-08-01
We report the observation of two kinds of novel nonhydrodynamic spin-transport phenomena of quasiparticles in superfluid 3B. We find a drastic low-temperature depression of the transverse quasiparticle spin-diffusion coefficient. In addition, we have done the first measurements of the Leggett-Takagi spin-relaxation time far outside the hydrodynamic regime. The observations of spin diffusion are shown to be in quantitative agreement with a kinetic-equation approach to quasiparticle spin dynamics.
Persistent spin current in nanodevices and definition of the spin current
Sun, Qing-Feng; Xie, X. C.; Wang, Jian
2008-01-01
We investigate two closely related subjects: (i) the existence of a pure persistent spin current without an accompanying charge current in a semiconducting mesoscopic device with a spin-orbit interaction (SOI) and (ii) the definition of the spin current in the presence of SOI. Through physical argument from four physical pictures in different aspects, we provide strong evidences that the equilibrium persistent spin current does exist in a device with SOI in the absence of any magnetic field or magnetic materials. This persistent spin current is an analog of the persistent charge current in a mesoscopic ring threaded by a magnetic flux, and it describes the real spin motion and can be measured experimentally. We then investigate the definition of the spin current. We point out that (i) the nonzero spin current in the equilibrium SOI device is the persistent spin current, (ii) the spin current is, in general, not conserved, and (iii) the Onsager relation is violated for the spin transport no matter what definition of the spin current is used. These issues, the nonzero spin current in the equilibrium case, the nonconserved spin current, and the violation of the Onsager relation, are intrinsic properties of spin transport. We note that the conventional definition of the spin current has very clear physical intuition and describes the spin motion very well. Therefore, we feel that the conventional definition of the spin current makes physical sense, and there is no need to modify it. (Note that this conclusion is not in contradiction with the opinions in our previous papers). In addition, the relationship between the persistent spin current and transport spin current, the persistent linear and angular spin currents in the SOI region of the hybrid ring, and the measurement of the persistent spin current are discussed. Finally, we show that if the spin-spin interaction is included into the Hamiltonian, the persistent spin current is automatically conserved using the
The calculation of indirect nuclear spin-spin coupling constants in large molecules.
Watson, Mark A; Sałek, Paweł; Macak, Peter; Jaszuński, Michał; Helgaker, Trygve
2004-09-20
We present calculations of indirect nuclear spin-spin coupling constants in large molecular systems, performed using density functional theory. Such calculations, which have become possible because of the use of linear-scaling techniques in the evaluation of the Coulomb and exchange-correlation contributions to the electronic energy, allow us to study indirect spin-spin couplings in molecules of biological interest, without having to construct artificial model systems. In addition to presenting a statistical analysis of the large number of short-range coupling constants in large molecular systems, we analyse the asymptotic dependence of the indirect nuclear spin-spin coupling constants on the internuclear separation. In particular, we demonstrate that, in a sufficiently large one-electron basis set, the indirect spin-spin coupling constants become proportional to the inverse cube of the internuclear separation, even though the diamagnetic and paramagnetic spin-orbit contributions to the spin-spin coupling constants separately decay as the inverse square of this separation. By contrast, the triplet Fermi contact and spin-dipole contributions to the indirect spin-spin coupling constants decay exponentially and as the inverse cube of the internuclear separation, respectively. Thus, whereas short-range indirect spin-spin coupling constants are usually dominated by the Fermi contact contribution, long-range coupling constants are always dominated by the negative diamagnetic spin-orbit contribution and by the positive paramagnetic spin-orbit contribution, with small spin-dipole and negligible Fermi contact contributions.
Spin-inversion in nanoscale graphene sheets with a Rashba spin-orbit barrier
Directory of Open Access Journals (Sweden)
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.
Suppression of spin-orbit effects in 1D system
Entin, M. V.; Magarill, L. I.
2004-01-01
We report the absence of spin effects such as spin-galvanic effect, spin polarization and spin current under static electric field and inter-spin-subband absorption in 1D system with spin-orbit interaction of arbitrary form. It was also shown that the accounting for the direct interaction of electron spin with magnetic field violates this statement.
Spin-transfer torque in spin filter tunnel junctions
Ortiz Pauyac, Christian
2014-12-08
Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green\\'s function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.
Spin-dependent quantum transport through an Aharonov-Bohm structure spin splitter
Institute of Scientific and Technical Information of China (English)
Li Yu-Xian
2008-01-01
Using the tight-binding model approximation, this paper investigates theoretically spin-dependent quantum trans-port through an Aharonov-Bohm (AB) interferometer. An external magnetic field is applied to produce the spin-polarization and spin current. The AB interferometer, acting as a spin splitter, separates the opposite spin polarization current. By adjusting the energy and the direction of the magnetic field, large spin-polarized current can be obtained.
Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions
Dellis, A. T.; Loulakis, M.; Kominis, I. K.
2013-01-01
The physics of spin exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We here report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin-noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise ...
Directory of Open Access Journals (Sweden)
Yu.A. Kruglyak
2015-12-01
Full Text Available Spin transport with the NEGF method in the spinor representation, in particular, spin valve, rotating magnetic contacts, spin precession and rotating spins, Zeeman and Rashba spin Hamiltonians, quantum spin Hall effect, calculation the spin potential, and four-component description of transport are discussed in the frame of the «bottom – up» approach of modern nanoelectronics.
Classical spin and quantum-mechanical descriptions of geometric spin frustration.
Dai, Dadi; Whangbo, Myung-Hwan
2004-07-08
Geometric spin frustration (GSF) in isolated plaquettes with local spin s, i.e., an equilateral-triangle spin trimer and a regular-tetrahedron spin tetramer, was examined on the basis of classical spin and quantum-mechanical descriptions to clarify their differences and similarities. An analytical proof was given for how the state degeneracy and the total spin S of their ground states depend on the local spin s. The quantum-mechanical conditions for the occurrence of GSF in isolated plaquettes were clarified, and their implications were explored. Corner sharing between plaquettes and how it affects GSF in the resulting spin systems was examined.
Spin transport in benzofurane bithiophene based organic spin valves
Directory of Open Access Journals (Sweden)
Mathieu Palosse
2014-01-01
Full Text Available In this paper we present spin transport in organic spin-valves using benzofurane bithiophene (BF3 as spacer layer between NiFe and Co ferromagnetic electrodes. The use of an AlOx buffer layer between the top electrode and the organic layer is discussed in terms of improvements of stacking topology, electrical transport and oxygen contamination of the BF3 layer. A study of magnetic hysteresis cycles evidences spin-valve behaviour. Transport properties are indicative of unshorted devices with non-linear I-V characteristics. Finally we report a magnetoresistance of 3% at 40 K and 10 mV in a sample with a 50 nm thick spacer layer, using an AlOx buffer layer.
Spin transport in benzofurane bithiophene based organic spin valves
Energy Technology Data Exchange (ETDEWEB)
Palosse, Mathieu; Séguy, Isabelle; Bedel-Pereira, Élena [CNRS, LAAS, 7 avenue du Colonel Roche, F-31400 Toulouse (France); Université de Toulouse (France); UPS, INSA, INP, ISAE (France); LAAS (France); CEMES, F-31077 Toulouse (France); Villeneuve-Faure, Christina [Université de Toulouse (France); UPS, INSA, INP, ISAE (France); LAAS (France); CEMES, F-31077 Toulouse (France); LAPLACE, Université Paul Sabatier, 118, route de Narbonne 31062 Toulouse Cedex 9 (France); Mallet, Charlotte; Frère, Pierre [MOLTECH-Anjou, UMR CNRS 6200, Université d’Angers, 2 Bd Lavoisier 49045 ANGERS Cedex (France); Warot-Fonrose, Bénédicte; Biziere, Nicolas [Université de Toulouse (France); UPS, INSA, INP, ISAE (France); LAAS (France); CEMES, F-31077 Toulouse (France); CNRS, CEMES-CNRS UPR 8011, 29 rue Jeanne Marvig, BP 94347, FR-31055 Toulouse Cedex 4 (France); Bobo, Jean-François, E-mail: jfbobo@cemes.fr [Université de Toulouse (France); UPS, INSA, INP, ISAE (France); LAAS (France); CEMES, F-31077 Toulouse (France); CNRS, CEMES-ONERA, NMH, 2 avenue Edouard Belin, FR-31055 Toulouse Cedex 4 (France)
2014-01-15
In this paper we present spin transport in organic spin-valves using benzofurane bithiophene (BF3) as spacer layer between NiFe and Co ferromagnetic electrodes. The use of an AlO{sub x} buffer layer between the top electrode and the organic layer is discussed in terms of improvements of stacking topology, electrical transport and oxygen contamination of the BF3 layer. A study of magnetic hysteresis cycles evidences spin-valve behaviour. Transport properties are indicative of unshorted devices with non-linear I-V characteristics. Finally we report a magnetoresistance of 3% at 40 K and 10 mV in a sample with a 50 nm thick spacer layer, using an AlO{sub x} buffer layer.
Energy Technology Data Exchange (ETDEWEB)
Babichev, Eugeny [Laboratoire de Physique Théorique, CNRS, Univ. Paris-Sud, Université Paris-Saclay,91405 Orsay (France); UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, GReCO,98bis boulevard Arago, F-75014 Paris (France); Marzola, Luca; Raidal, Martti [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Laboratory of Theoretical Physics, Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Schmidt-May, Angnis [Institut für Theoretische Physik, Eidgenössische Technische Hochschule Zürich,Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland); Urban, Federico; Veermäe, Hardi [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Strauss, Mikael von [UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, GReCO,98bis boulevard Arago, F-75014 Paris (France)
2016-09-12
We provide further details on a recent proposal addressing the nature of the dark sectors in cosmology and demonstrate that all current observations related to Dark Matter can be explained by the presence of a heavy spin-2 particle. Massive spin-2 fields and their gravitational interactions are uniquely described by ghost-free bimetric theory, which is a minimal and natural extension of General Relativity. In this setup, the largeness of the physical Planck mass is naturally related to extremely weak couplings of the heavy spin-2 field to baryonic matter and therefore explains the absence of signals in experiments dedicated to Dark Matter searches. It also ensures the phenomenological viability of our model as we confirm by comparing it with cosmological and local tests of gravity. At the same time, the spin-2 field possesses standard gravitational interactions and it decays universally into all Standard Model fields but not into massless gravitons. Matching the measured DM abundance together with the requirement of stability constrains the spin-2 mass to be in the 1 to 100 TeV range.
Daly, Ruth A
2009-01-01
Beam powers and black hole masses of 48 extended radio sources are combined to obtain lower bounds on the spins and magnetic field strengths of supermassive black holes. This is done in the context of the models of Blandford & Znajek (1977) (the 'BZ' model) and Meier (1999); a parameterization for bounds in the context of other models is suggested. The bounds obtained for very powerful classical double radio sources in the BZ model are consistent with black hole spins of order unity for sources at high redshift. The black hole spins are largest for the highest redshift sources and decrease for sources at lower redshift; the sources studied have redshifts between zero and two. Lower power radio sources associated with central dominant galaxies may have black hole spins that are significantly less than one. Combining this analysis with other results suggests that the maximum values of black hole spin associated with powerful radio galaxies decline from values of order unity at a redshift of 2 to values of o...
Oprea, Corneliu I.; Rinkevicius, Zilvinas; Vahtras, Olav; Ågren, Hans; Ruud, Kenneth
2005-07-01
This work outlines the calculation of indirect nuclear spin-spin coupling constants with spin-orbit corrections using density functional response theory. The nonrelativistic indirect nuclear spin-spin couplings are evaluated using the linear response method, whereas the relativistic spin-orbit corrections are computed using quadratic response theory. The formalism is applied to the homologous systems H2X (X=O,S,Se,Te) and XH4 (X =C,Si,Ge,Sn,Pb) to calculate the indirect nuclear spin-spin coupling constants between the protons. The results confirm that spin-orbit corrections are important for compounds of the H2X series, for which the electronic structure allows for an efficient coupling between the nuclei mediated by the spin-orbit interaction, whereas in the case of the XH4 series the opposite situation is encountered and the spin-orbit corrections are negligible for all compounds of this series. In addition we analyze the performance of the density functional theory in the calculations of nonrelativistic indirect nuclear spin-spin coupling constants.
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.)
Spin-Orbit Coupling and Spin Textures in Optical Superlattices
Li, Junru; Shteynas, Boris; Burchesky, Sean; Top, Furkan Cagri; Su, Edward; Lee, Jeongwon; Jamison, Alan O; Ketterle, Wolfgang
2016-01-01
We proposed and demonstrated a new approach for realizing spin orbit coupling with ultracold atoms. We use orbital levels in a double well potential as pseudospin states. Two-photon Raman transitions between left and right wells induce spin-orbit coupling. This scheme does not require near resonant light, features adjustable interactions by shaping the double well potential, and does not depend on special properties of the atoms. A pseudospinor Bose-Einstein condensate spontaneously acquires an antiferromagnetic pseudospin texture which breaks the lattice symmetry similar to a supersolid.
Second post-Newtonian Lagrangian dynamics of spinning compact binaries
Energy Technology Data Exchange (ETDEWEB)
Huang, Li; Wu, Xin [Nanchang University, Department of Physics and Institute of Astronomy, Nanchang (China); Ma, DaZhu [Hubei University for Nationalities, School of Science, Enshi (China)
2016-09-15
The leading-order spin-orbit coupling is included in a post-Newtonian Lagrangian formulation of spinning compact binaries, which consists of the Newtonian term, first post-Newtonian (1PN) and 2PN non-spin terms and 2PN spin-spin coupling. This leads to a 3PN spin-spin coupling occurring in the derived Hamiltonian. The spin-spin couplings are mainly responsible for chaos in the Hamiltonians. However, the 3PN spin-spin Hamiltonian is small and has different signs, compared with the 2PN spin-spin Hamiltonian equivalent to the 2PN spin-spin Lagrangian. As a result, the probability of the occurrence of chaos in the Lagrangian formulation without the spin-orbit coupling is larger than that in the Lagrangian formulation with the spin-orbit coupling. Numerical evidences support this claim. (orig.)
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.
Joule heating in spin Hall geometry
Taniguchi, Tomohiro
2016-07-01
The theoretical formula for the entropy production rate in the presence of spin current is derived using the spin-dependent transport equation and thermodynamics. This theory is applicable regardless of the source of the spin current, for example, an electric field, a temperature gradient, or the Hall effect. It reproduces the result in a previous work on the dissipation formula when the relaxation time approximation is applied to the spin relaxation rate. By using the developed theory, it is found that the dissipation in the spin Hall geometry has a contribution proportional to the square of the spin Hall angle.
DEFF Research Database (Denmark)
Clausen, Kurt Nørgaard; Lebech, Bente
1980-01-01
Spin wave excitations in a single crystal of Ho2Co17 have been studied at 4.8 and 78 K. The results are discussed in terms of a linear spin wave model. At 78 K both ground state and excited state spin waves are observed.......Spin wave excitations in a single crystal of Ho2Co17 have been studied at 4.8 and 78 K. The results are discussed in terms of a linear spin wave model. At 78 K both ground state and excited state spin waves are observed....
Thermal Spin Dynamics of Yttrium Iron Garnet
Barker, Joseph; Bauer, Gerrit E. W.
2016-11-01
The magnetic insulator yttrium iron garnet can be grown with near perfection and is therefore and ideal conduit for spin currents. It is a complex material with 20 magnetic moments in the unit cell. In spite of being a ferrimagnet, YIG is almost always modeled as a simple ferromagnet with a single spin wave mode. We use the method of atomistic spin dynamics to study the temperature evolution of the full spin wave spectrum, in quantitative agreement with neutron scattering experiments. The antiferromagnetic or optical mode is found to suppress the spin Seebeck effect at room temperature and beyond due to thermally pumped spin currents with opposite polarization to the ferromagnetic mode.
Spin flipping a stored polarized proton beam
Caussyn, D. D.; Derbenev, Ya. S.; Ellison, T. J.; Lee, S. Y.; Rinckel, T.; Schwandt, P.; Sperisen, F.; Stephenson, E. J.; von Przewoski, B.; Blinov, B. B.; Chu, C. M.; Courant, E. D.; Crandell, D. A.; Kaufman, W. A.; Krisch, A. D.; Nurushev, T. S.; Phelps, R. A.; Ratner, L. G.; Wong, V. K.; Ohmori, C.
1994-11-01
We recently studied the spin flipping of a vertically polarized, stored 139-MeV proton beam. To flip the spin, we induced an rf depolarizing resonance by sweeping our rf solenoid magnet's frequency through the resonance frequency. With multiple spin flips, we found a polarization loss of 0.0000+/-0.0005 per spin flip under the best conditions; this loss increased significantly for small changes in the conditions. Minimizing the depolarization during each spin flip is especially important because frequent spin flipping could significantly reduce the systematic errors in stored polarized-beam experiments.
Spin gravitational resonance and graviton detection
Quach, James Q
2016-01-01
We develop a gravitational analogue of spin magnetic resonance, called spin gravitational resonance, whereby a gravitational wave interacts with a magnetic field to produce a spin transition. In particular, an external magnetic field separates the energy spin states of a spin-1/2 particle, and the presence of the gravitational wave produces a perturbation in the components of the magnetic field orthogonal to the gravitational wave propagation. In this framework we test Dyson's conjecture that individual gravitons cannot be detected. Although we find no fundamental laws preventing single gravitons being detected with spin gravitational resonance, we show that it cannot be used in practice, in support of Dyson's conjecture.
Spin rotators and split Siberian Snakes
Energy Technology Data Exchange (ETDEWEB)
Roser, Thomas
1994-03-01
The study of spin effects in the collision of polarized high energy beams requires flexible and compact spin rotators to manipulate the beam polarization direction. Design criteria and specific examples are presented for high energy, orbit transparent spin rotators ranging from small angle rotators to be used for the excitation of spin resonances to large angle rotators to be used as Siberian Snakes. It is shown that all the requirements for spin rotators can be met with a simple 6-magnet spin rotator design, for which a complete continuous solution is presented.
Spin rotators and split Siberian Snakes
Energy Technology Data Exchange (ETDEWEB)
Roser, T. (Brookhaven National Lab., Upton, NY (United States))
1994-03-22
The study of spin effects in the collision of polarized high energy beams requires flexible and compact spin rotators to manipulate the beam polarization direction. Design criteria and specific examples are presented for high energy, orbit transparent spin rotators ranging from small angle rotators to be used for the excitation of spin resonances to large angle rotators to be used as Siberian Snakes. It is shown that all the requirements for spin rotators can be met with a simple 6-magnet spin rotator design, for which a complete continuous solution is presented. (orig.)
Armour, R S
2003-01-01
Requiring covariance of Maxwell's equations without {\\it a priori} imposing charge invariance allows for both spin-1 and spin-1/2 transformations of the complete Maxwell field and current. The spin-1/2 case yields new transformation rules, with new invariants, for all traditional Maxwell field and source quantities. The accompanying spin-1/2 representations of the Lorentz group employ the Lorentz metric, and consequently the primary invariants of the spin-1/2 Maxwell field are also spin-1 invariants, for example, $\\Phi^2 - {\\bf A}^2$, ${\\bf E}^2 - {\\bf B}^2 + 2i {\\bf E} \\bm{\\cdot} {\\bf B} - ({\\partial}_{0}{\\Phi} + {\\bm{\
Geometry of Spin: Clifford Algebraic Approach
Indian Academy of Sciences (India)
Rukhsan-Ul-Haq
2016-12-01
Spin is a fundamental degree of freedom of matter and radiation.In quantum theory, spin is represented by Pauli matrices.Then the various algebraic properties of Pauli matricesare studied as properties of matrix algebra. What has beenshown in this article is that Pauli matrices are a representationof Clifford algebra of spin and hence all the propertiesof Pauli matrices follow from the underlying algebra. Cliffordalgebraic approach provides a geometrical and henceintuitive way to understand quantum theory of spin, and isa natural formalism to study spin. Clifford algebraic formalismhas lot of applications in every field where spin plays animportant role.
Effect of isoscalar spin-triplet pairings on spin-isospin responses in $sd-$ shell nuclei
Sagawa, H; Sasano, M
2016-01-01
The spin magnetic dipole transitions and the neutron-proton spin-spin correlations in $sd-$shell even-even nuclei with $N=Z$ are investigated using shell model wave functions. The isoscalar spin-triplet pairing correlation provides a substantial quenching effect on the spin magnetic dipole transitions, especially the isovector (IV) ones. Consequently, an enhanced isoscalar spin-triplet pairing interaction influences the proton-neutron spin-spin correlation deduced from the difference between the isoscalar (IS) and the IV sum rule strengths. The effect of the $\\Delta$ ($\\Delta_{33}$ resonance)-hole coupling is examined in the IV spin transition and the spin-spin correlations of the ground states.
Analytic bootstrap at large spin
Kaviraj, Apratim; Sinha, Aninda
2015-01-01
We use analytic conformal bootstrap methods to determine the anomalous dimensions and OPE coefficients for large spin operators in general conformal field theories in four dimensions containing a scalar operator of conformal dimension $\\Delta_\\phi$. It is known that such theories will contain an infinite sequence of large spin operators with twists approaching $2\\Delta_\\phi+2n$ for each integer $n$. By considering the case where such operators are separated by a twist gap from other operators at large spin, we analytically determine the $n$, $\\Delta_\\phi$ dependence of the anomalous dimensions. We find that for all $n$, the anomalous dimensions are negative for $\\Delta_\\phi$ satisfying the unitarity bound, thus extending the Nachtmann theorem to non-zero $n$. In the limit when $n$ is large, we find agreement with the AdS/CFT prediction corresponding to the Eikonal limit of a 2-2 scattering with dominant graviton exchange.
Spin-orbit-coupled superconductivity.
Lo, Shun-Tsung; Lin, Shih-Wei; Wang, Yi-Ting; Lin, Sheng-Di; Liang, C-T
2014-06-25
Superconductivity and spin-orbit (SO) interaction have been two separate emerging fields until very recently that the correlation between them seemed to be observed. However, previous experiments concerning SO coupling are performed far beyond the superconducting state and thus a direct demonstration of how SO coupling affects superconductivity remains elusive. Here we investigate the SO coupling in the critical region of superconducting transition on Al nanofilms, in which the strength of disorder and spin relaxation by SO coupling are changed by varying the film thickness. At temperatures T sufficiently above the superconducting critical temperature T(c), clear signature of SO coupling reveals itself in showing a magneto-resistivity peak. When T superconductivity. By studying such magneto-resistivity peaks under different strength of spin relaxation, we highlight the important effects of SO interaction on superconductivity.
Rojas-Sánchez, J-C; Reyren, N; Laczkowski, P; Savero, W; Attané, J-P; Deranlot, C; Jamet, M; George, J-M; Vila, L; Jaffrès, H
2014-03-14
Through combined ferromagnetic resonance, spin pumping, and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of ℓsfPt=3.4±0.4 nm and θSHEPt=0.056±0.010 for the respective spin diffusion length and spin Hall angle for Pt. Our data and model emphasize the partial depolarization of the spin current at each interface due to spin-memory loss. Our model reconciles the previously published spin Hall angle values and explains the different scaling lengths for the ferromagnetic damping and the spin Hall effect induced voltage.
Spin waves in exchange-coupled double layers in the presence of spin torques
Baláž, Pavel; Barnaś, Józef
2015-03-01
Spin-wave spectra of a double magnetic layer are calculated theoretically in the macroscopic limit. Magnetic dynamics is described in terms of the Landau-Lifshitz-Gilbert equation, and both static (of the Ruderman-Kittel-Kasuya-Yosida type) and dynamic (via spin pumping) interlayer couplings are taken into account. The influence of spin pumping and spin transfer torque on the spin-wave spectra (frequency and damping factor) has been studied for both parallel and antiparallel magnetic configurations. The spin-wave spectrum in the parallel magnetic state is reciprocal, while in the antiparallel configuration it is nonreciprocal. In both cases, a substantial reduction of the spin-wave lifetimes due to spin pumping to the nonmagnetic metallic layers has been found. In the parallel configuration, this reduction appears mainly for optical modes, while in the antiparallel configuration, it is remarkable for all modes. In turn, the spin torque due to spin current flowing from a metallic layer, created for instance by the spin Hall effect, gives rise to significant changes in the damping factors as well, but these modifications depend on the sign of spin current. For one spin current orientation, the spin-wave damping becomes reduced and may disappear for some modes at a specific threshold value of the spin current, indicating magnetic instability in the system due to spin transfer torque. For the opposite spin current, the damping is enhanced, which indicates stabilization of the corresponding magnetic state.
Ballistic spin transport in exciton gases
Kavokin, A. V.; Vladimirova, M.; Jouault, B.; Liew, T. C. H.; Leonard, J. R.; Butov, L. V.
2013-11-01
Traditional spintronics relies on spin transport by charge carriers, such as electrons in semiconductor crystals. The challenges for the realization of long-range electron spin transport include rapid spin relaxation due to electron scattering. Scattering and, in turn, spin relaxation can be effectively suppressed in excitonic devices where the spin currents are carried by electrically neutral bosonic quasiparticles: excitons or exciton-polaritons. They can form coherent quantum liquids that carry spins over macroscopic distances. The price to pay is a finite lifetime of the bosonic spin carriers. We present the theory of exciton ballistic spin transport which may be applied to a range of systems supporting bosonic spin transport, in particular to indirect excitons in coupled quantum wells. We describe the effect of spin-orbit interaction for the electron and the hole on the exciton spin, account for the Zeeman effect induced by external magnetic fields and long-range and short-range exchange splittings of the exciton resonances. We also consider exciton transport in the nonlinear regime and discuss the definitions of the exciton spin current, polarization current, and spin conductivity.
Extrinsic spin Hall effect in graphene
Rappoport, Tatiana
The intrinsic spin-orbit coupling in graphene is extremely weak, making it a promising spin conductor for spintronic devices. In addition, many applications also require the generation of spin currents in graphene. Theoretical predictions and recent experimental results suggest one can engineer the spin Hall effect in graphene by greatly enhancing the spin-orbit coupling in the vicinity of an impurity. The extrinsic spin Hall effect then results from the spin-dependent skew scattering of electrons by impurities in the presence of spin-orbit interaction. This effect can be used to efficiently convert charge currents into spin-polarized currents. I will discuss recent experimental results on spin Hall effect in graphene decorated with adatoms and metallic cluster and show that a large spin Hall effect can appear due to skew scattering. While this spin-orbit coupling is small if compared with what it is found in metals, the effect is strongly enhanced in the presence of resonant scattering, giving rise to robust spin Hall angles. I will present our single impurity scattering calculations done with exact partial-wave expansions and complement the analysis with numerical results from a novel real-space implementation of the Kubo formalism for tight-binding Hamiltonians. The author acknowledges the Brazilian agencies CNPq, CAPES, FAPERJ and INCT de Nanoestruturas de Carbono for financial support.
Spin-flip reflection at the normal metal-spin superconductor interface
Lv, Peng; Guo, Ai-Min; Li, Huaiyu; Liu, Chunxiao; Xie, X. C.; Sun, Qing-Feng
2017-03-01
We study spin transport through a normal metal-spin superconductor junction. A spin-flip reflection is demonstrated at the interface, where a spin-up electron incident from the normal metal can be reflected as a spin-down electron and the spin 2 ×ℏ /2 will be injected into the spin superconductor. When the (spin) voltage is smaller than the gap of the spin superconductor, the spin-flip reflection determines the transport properties of the junction. We consider both graphene-based (linear-dispersion-relation) and quadratic-dispersion-relation normal metal-spin superconductor junctions in detail. For the two-dimensional graphene-based junction, the spin-flip reflected electron can be along the specular direction (retro-direction) when the incident and reflected electron locates in the same band (different bands). A perfect spin-flip reflection can occur when the incident electron is normal to the interface, and the reflection coefficient is slightly suppressed for the oblique incident case. As a comparison, for the one-dimensional quadratic-dispersion-relation junction, the spin-flip reflection coefficient can reach 1 at certain incident energies. In addition, both the charge current and the spin current under a charge (spin) voltage are studied. The spin conductance is proportional to the spin-flip reflection coefficient when the spin voltage is less than the gap of the spin superconductor. These results will help us get a better understanding of spin transport through the normal metal-spin superconductor junction.
Quantum crystals and spin chains
Energy Technology Data Exchange (ETDEWEB)
Dijkgraaf, Robbert [KdV Institute for Mathematics, University of Amsterdam, Plantage Muidergracht 24, 1018 TV Amsterdam (Netherlands); Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands); Orlando, Domenico [Institut de Physique, Universite de Neuchatel, Rue Breguet 1, CH-2000 Neuchatel (Switzerland); Reffert, Susanne [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)], E-mail: sreffert@gmail.com
2009-04-21
In this article, we discuss the quantum version of the melting crystal corner in one, two, and three dimensions, generalizing the treatment for the quantum dimer model. Using a mapping to spin chains we find that the two-dimensional case (growth of random partitions) is integrable and leads directly to the Hamiltonian of the Heisenberg XXZ ferromagnet. The three-dimensional case of the melting crystal corner is described in terms of a system of coupled XXZ spin chains. We give a conjecture for its mass gap and analyze the system numerically.
Quantum crystals and spin chains
Dijkgraaf, Robbert; Orlando, Domenico; Reffert, Susanne
2009-04-01
In this article, we discuss the quantum version of the melting crystal corner in one, two, and three dimensions, generalizing the treatment for the quantum dimer model. Using a mapping to spin chains we find that the two-dimensional case (growth of random partitions) is integrable and leads directly to the Hamiltonian of the Heisenberg XXZ ferromagnet. The three-dimensional case of the melting crystal corner is described in terms of a system of coupled XXZ spin chains. We give a conjecture for its mass gap and analyze the system numerically.
Stigloher, J.; Decker, M.; Körner, H. S.; Tanabe, K.; Moriyama, T.; Taniguchi, T.; Hata, H.; Madami, M.; Gubbiotti, G.; Kobayashi, K.; Ono, T.; Back, C. H.
2016-07-01
We report the experimental observation of Snell's law for magnetostatic spin waves in thin ferromagnetic Permalloy films by imaging incident, refracted, and reflected waves. We use a thickness step as the interface between two media with different dispersion relations. Since the dispersion relation for magnetostatic waves in thin ferromagnetic films is anisotropic, deviations from the isotropic Snell's law known in optics are observed for incidence angles larger than 25 ° with respect to the interface normal between the two magnetic media. Furthermore, we can show that the thickness step modifies the wavelength and the amplitude of the incident waves. Our findings open up a new way of spin wave steering for magnonic applications.
Spin structures in antiferromagnetic nanoparticles
DEFF Research Database (Denmark)
Brok, Erik
in aqueous suspension was controlled by a hydrothermal treatment and by changing the ionic strenght of the suspension. Interestingly addition of NaCl to the suspension resulted in the particles aggregating in long linear chains, with neighbouring particles aligned along a common [001] axis of the hexagonal......, proposed to explain the unusual magnetic properties of the mineral. In summary the thesis have demonstrated methods for investigation of spin structures in magnetic nanoparticles. In particular, the classical model of the temperature dependence of canted spin structures sucessfully explains many...
Scalar spin of elementary fermions
Energy Technology Data Exchange (ETDEWEB)
Jourjine, A., E-mail: jourjine@pks.mpg.de
2014-01-20
We show that, using the experimentally observed values of CKM and PMNS mixing matrices, all known elementary fermions can be assigned a new quantum number, the scalar spin, in a unique way. This is achieved without introduction of new degrees of freedom. The assignment implies that tau-neutrino should be an anti-Dirac spinor, while mu–tau leptons and charm–top, strange–bottom quarks form Dirac–anti-Dirac scalar spin doublets. The electron and its neutrino remain as originally described by Dirac.
Spin tunnelling in mesoscopic systems
Indian Academy of Sciences (India)
Anupam Garg
2001-02-01
We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic ﬁeld, vanishing completely at special points in the space of magnetic ﬁelds, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.
Skein spaces and spin structures
Barrett, John W
1995-01-01
This paper relates skein spaces based on the Kauffman bracket and spin structures. A spin structure on an oriented 3-manifold provides an isomorphism between the skein space for parameter A and the skein space for parameter -A. There is an application to Penrose's binor calculus, which is related to the tensor calculus of representations of SU(2). The perspective developed here is that this tensor calculus is actually a calculus of spinors on the plane, and the matrices a re determined by a t...
Spin-Up/Spin-Down models for Type Ia Supernovae
Di Stefano, R; Claeys, J S W
2011-01-01
In the single degenerate scenario for Type Ia supernova (SNeIa), a white dwarf (WD) must gain a significant amount of matter from a companion star. Because the accreted mass carries angular momentum, the WD is likely to achieve fast spin periods, which can increase the critical mass, $M_{crit}$, needed for explosion. When $M_{crit}$ is higher than the maximum mass achieved by the WD, the WD must spin down before it can explode. This introduces a delay between the time at which the WD has completed its epoch of mass gain and the time of the explosion. Matter ejected from the binary during mass transfer therefore has a chance to become diffuse, and the explosion occurs in a medium with a density similar to that of typical regions of the interstellar medium. Also, either by the end of the WD's mass increase or else by the time of explosion, the donor may exhaust its stellar envelope and become a WD. This alters, generally diminishing, explosion signatures related to the donor star. Nevertheless, the spin-up/spin...
Spin-spin correlations of magnetic adatoms on graphene
Güçlü, A. D.; Bulut, Nejat
2015-03-01
We study the interaction between two magnetic adatom impurities in graphene using the Anderson model. The two-impurity Anderson Hamiltonian is solved numerically by using the quantum Monte Carlo technique. We find that the interimpurity spin susceptibility is strongly enhanced at low temperatures, significantly diverging from the well-known Ruderman-Kittel-Kasuya-Yoshida result which decays as R-3.
Long-range spin Seebeck effect and acoustic spin pumping.
Uchida, K; Adachi, H; An, T; Ota, T; Toda, M; Hillebrands, B; Maekawa, S; Saitoh, E
2011-10-01
Imagine that a metallic wire is attached to a part of a large insulator, which itself exhibits no magnetization. It seems impossible for electrons in the wire to register where the wire is positioned on the insulator. Here we found that, using a Ni₈₁Fe₁₉/Pt bilayer wire on an insulating sapphire plate, electrons in the wire recognize their position on the sapphire. Under a temperature gradient in the sapphire, surprisingly, the voltage generated in the Pt layer is shown to reflect the wire position, although the wire is isolated both electrically and magnetically. This non-local voltage is due to the coupling of spins and phonons: the only possible carrier of information in this system. We demonstrate this coupling by directly injecting sound waves, which realizes the acoustic spin pumping. Our finding provides a persuasive answer to the long-range nature of the spin Seebeck effect, and it opens the door to 'acoustic spintronics' in which sound waves are exploited for constructing spin-based devices.
Spin-orbit interactions of light
Bliokh, K Y; Nori, F; Zayats, A V
2015-01-01
Light carries spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Modern nano-optics, photonics, and plasmonics, tend to explore subwavelength scales and additional degrees of freedom of structured, i.e., spatially-inhomogeneous, optical fields. In such fields, spin and orbital properties become strongly coupled with each other. We overview the fundamental origins and important applications of the main spin-orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces), as well as robust spin-directional coupling via evanescent near fields. We show that spin-orbit interactions are inherent in all basic optical processes, and they play a crucial role at subwavelength scales and structures in modern optics.
Scattering theory of the Johnson spin transistor
Geux, Linda S.; Brataas, Arne; Bauer, Gerrit E. W.
1999-01-01
We discuss a simple, semiclassical scattering theory for spin-dependent transport in a many-terminal formulation, with special attention to the four terminal device of Johnson referred to as spin transistor
Wavefunctions for Particles with Arbitrary Spin
Institute of Scientific and Technical Information of China (English)
HUANG Shi-Zhong; RUAN Tu-Nan; WU Ning; ZHENG Zhi-Peng
2002-01-01
By solving rigorously the relativistic wave equations derived bom Bargmann-Wigner equation for arbitrary spin, the relativistic w avefunctions in momentum representation for particles with arbitrary spin are deduced.
Stern-Gerlach experiment with higher spins
Tekin, Bayram
2016-05-01
We analyze idealized sequential Stern-Gerlach (SG) experiments with higher spin particles. This analysis serves at least two purposes: the widely discussed spin-1/2 case leads to some misunderstandings since the probabilities are always evenly distributed for the sequential orthogonal magnets, which does not generalize to higher spins. A detailed discussion of the higher spin case, as is done here, is highly useful. Secondly, the Wigner rotation matrices for generic spins become conceptually more transparent with this physical example. We also give compact formulas for the probabilities in terms of the angle between the sequential SG apparatus for generic spins. We work out the spin-1/2, spin-1 cases explicitly. Since there are some confusing issues regarding the actual experiment, we also compile a ‘facts and fiction’ section on the SG experiments.
Spin flipping in rings with Siberian Snakes
Energy Technology Data Exchange (ETDEWEB)
Mane, S.R. [Convergent Computing Inc., P.O. Box 561, Shoreham, NY 11786 (United States)], E-mail: srmane@optonline.net
2009-07-01
I display numerical spin tracking simulations for spin flippers in model storage rings with full or nearly full Siberian Snakes. In many cases, the results differ from the predictions using the Froissart-Stora formula.
Universal Spin-Momentum Locked Optical Forces
Kalhor, Farid; Jacob, Zubin
2015-01-01
Evanescent electromagnetic waves possess spin-momentum locking, where the direction of propagation (momentum) is locked to the inherent polarization of the wave (transverse spin). We study the optical forces arising from this universal phenomenon and show that the fundamental origin of recently reported non-trivial optical chiral forces is spin-momentum locking. For evanescent waves, we show that the direction of energy flow, direction of decay, and direction of spin follow a right hand rule for three different cases of total internal reflection, surface plasmon polaritons, and $HE_{11}$ mode of an optical fiber. Furthermore, we explain how the recently reported phenomena of lateral optical force on chiral and achiral particles is caused by the transverse spin of the evanescent field and the spin-momentum locking phenomenon. Finally, we propose an experiment to identify the unique lateral forces arising from the transverse spin in the optical fiber and point to fundamental differences of the spin density from...
Entanglement Enhancement in an XY Spin Chain
Institute of Scientific and Technical Information of China (English)
SU Xiao-Qiang
2011-01-01
We study evolution of entanglement in an XY-type spin channel and find that the entanglement can be enhanced by the spin channel. The parameter regions of the initial states for different numbers of sites are obtained.Furthermore, we consider a common spin environment coupling to the spin chains and find that the entanglement enhancement can also be implemented only for the chains with the odd numbers of sites.%@@ We study evolution of entanglement in an XY-type spin channel and find that the entanglement can be enhanced by the spin channel.The parameter regions of the initial states for different numbers of sites are obtained.Furthermore,we consider a common spin environment coupling to the spin chains and find that the entanglement enhancement can also be implemented only for the chains with the odd numbers of sites.
Quantum limited heterodyne detection of spin noise
Cronenberger, S.; Scalbert, D.
2016-09-01
Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. In this article, we propose an extension of this technique based on optical heterodyne detection of spin noise, which provides several key advantages compared to conventional spin noise spectroscopy: detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers, quantum limited sensitivity even in case of very weak probe power, and possible amplification of the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-doped GaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution of g-factors, Δg/g = 0.49%.
Bubbfil spinning for mass-production of nanofibers
Directory of Open Access Journals (Sweden)
Chen Rou-Xi
2014-01-01
Full Text Available Bubbfil spinning is a generalized bubble electrospinning, including bubble spinning, blown-bubble spinning, and membrane spinning, for mass production of nanofiber. This paper shows small bubbles in liquid membrane are the best candidate for uniform nanofibers.
Squeezing in the Real and Imaginary Spin Coherent States
Institute of Scientific and Technical Information of China (English)
YAN Dong; WANG Xiao-Guang; WU Ling-An
2005-01-01
@@ We study spin squeezing properties in the real and imaginary spin coherent states. We obtain analytical expressions of two spin squeezing parameters via a novel ladder operator formalism of the spin coherent state and the generation function method.
The proton spin structure; La structure en spin du proton
Energy Technology Data Exchange (ETDEWEB)
Breton, V.
1996-05-13
The author presents first the theoretical frame of the nucleon spin structure study carried out through the deep inelastic scattering of polarised leptons on a polarised target. The interest of the lepton scattering reaction to study the hadronic structure is discussed and the formalism of the inclusive inelastic scattering presented. If the target and the beam are both polarised, the formalism enables to connect the experimentally measured asymmetries to the contribution of quarks to the spin of nucleon. The recent knowledge about the nucleon spin structure is also presented. The Bjorken sum rule is then discussed: it correlates the difference of spin structure between proton and neutron to the neutron lifetime. Then, the author mentions the experimental results of SMC (CERN) and E142, E143 (SLAC). The transition from rough asymmetry to the g sub 1 structure function integral is discussed as well as the main causes of uncertainty. Compared to theoretical data, the measurements confirm the reliability of the Bjorken sum rule. They also confirm the deficit of the quark contribution with respect to the naive unpolarized strange sea model. The possible origins of this discrepancy and the contributions of the current and planned experiments are also discussed. Finally, the author brings up the next major step for nucleon spin studies: the estimation of the gluon contribution. He discusses the experimental knowledge about the polarised gluon distribution function with regard to the multiple existing parameter set. Concerning the experimental determination of this distribution function, outlooks are proposed with respect to feasibility on current experimental facilities. (N.T.). 134 refs.
Magnus effects on spinning transonic missiles
Seginer, A.; Rosenwasser, I.
1983-01-01
Magnus forces and moments were measured on a basic-finner model spinning in transonic flow. Spin was induced by canted fins or by full-span or semi-span, outboard and inboard roll controls. Magnus force and moment reversals were caused by Mach number, reduced spin rate, and angle of attack variations. Magnus center of pressure was found to be independent of the angle of attack but varied with the Mach number and model configuration or reduced spin rate.
Spin and charge necklaces at commensurate filling
Energy Technology Data Exchange (ETDEWEB)
Kikoin, K [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Kiselev, M N, E-mail: konstk@post.tau.ac.i [The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste (Italy)
2009-03-01
The charge and spin properties of spin chains decorated with dimers and closed trimers (equilateral triangles) with commensurate partial filling (1/4 and 1/3, respectively) are considered. It is shown that due to the charge separation both systems prefer the ground state with even occupation per elementary cell, where the spin spectrum possesses the Haldane gap for negative spin exchange and magnon-like for positive coupling. The charge spectrum is always gapped.
Origin of the spin Seebeck effect
Kehlberger, Andreas
2015-01-01
Der Spin Seebeck Effekt repräsentiert einen neuartigen Spin kalorischen Effekt mit vorteilhaften und aussichtsreichen Eigenschaften für Anwendungen in den Gebieten der Spintronik und Thermoelektrik.rnIn dieser Arbeit präsentieren wir eine umfangreiche Untersuchung des Spin Seebeck Effekts in isolierenden, magnetischen Granaten und geben Antworten zum kontrovers diskutierten Ursprung des Effekts. Um dieses Ziel zu erreichen, haben wir die Abhängigkeit des Spin Seebeck Effekts von der Dicke des...
Applications of Neural Networks in Spinning Prediction
Institute of Scientific and Technical Information of China (English)
程文红; 陆凯
2003-01-01
The neural network spinning prediction model (BP and RBF Networks) trained by data from the mill can predict yarn qualities and spinning performance. The input parameters of the model are as follows: yarn count, diameter, hauteur, bundle strength, spinning draft, spinning speed, traveler number and twist.And the output parameters are: yarn evenness, thin places, tenacity and elongation, ends-down.Predicting results match the testing data well.
Electrical spin injection and accumulation at room temperature in an all-metal mesoscopic spin valve
Jedema, F.J.; Filip, A.T.; Wees, B.J. van
2001-01-01
Finding a means to generate, control and use spin-polarized currents represents an important challenge for spin-based electronics, or `spintronics'. Spin currents and the associated phenomenon of spin accumulation can be realized by driving a current from a ferromagnetic electrode into a non-magneti
Thermal spin pumping and magnon-phonon-mediated spin-Seebeck effect
Uchida, K.; Ota, T.; Adachi, H.; Xiao, J.; Nonaka, T.; Kajiwara, Y.; Bauer, G.E.W.; Maekawa, S.; Saitoh, E.
2012-01-01
The spin-Seebeck effect (SSE) in ferromagnetic metals and insulators has been investigated systematically by means of the inverse spin-Hall effect (ISHE) in paramagnetic metals. The SSE generates a spin voltage as a result of a temperature gradient in a ferromagnet, which injects a spin current into
Spin-flux phase in the Kondo lattice model with classical localized spins
Agterberg, DF; Yunoki, S
2000-01-01
We provide numerical evidence that a spin-flux phase exists as a ground state of the Kondo lattice model with classical local spins on a square lattice. This state manifests itself as a double-e magnetic order in the classical spins with spin density at both (0, pi) and (pi ,0) and further exhibits
High-spin nuclear spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Diamond, R.M.
1986-07-01
High-spin spectroscopy is the study of the changes in nuclear structure, properties, and behavior with increasing angular momentum. It involves the complex interplay between collective and single-particle motion, between shape and deformation changes, particle alignments, and changes in the pairing correlations. A review of progress in theory, experimentation, and instrumentation in this field is given. (DWL)
Energy Technology Data Exchange (ETDEWEB)
Switzner, Nathan; Henry, Dick
2009-03-20
In a second development order, spin-forming equipment was again evaluated using the test shape, a hemispherical shell. In this second development order, pure vanadium and alloy titanium (Ti-6Al-4V) were spin-formed, as well as additional copper and 21-6-9 stainless. In the first development order the following materials had been spin-formed: copper (alloy C11000 ETP), 6061 aluminum, 304L stainless steel, 21-6-9 stainless steel, and tantalum-2.5% tungsten. Significant challenges included properly adjusting the rotations-per-minute (RPM), cracking at un-beveled edges and laser marks, redressing of notches, surface cracking, non-uniform temperature evolution in the titanium, and cracking of the tailstock. Lessons learned were that 300 RPM worked better than 600 RPM for most materials (at the feed rate of 800 mm/min); beveling the edges to lower the stress reduces edge cracking; notches, laser marks, or edge defects in the preform doom the process to cracking and failure; coolant is required for vanadium spin-forming; increasing the number of passes to nine or more eliminates surface cracking for vanadium; titanium develops a hot zone in front of the rollers; and the tailstock should be redesigned to eliminate the cylindrical stress concentrator in the center.
Spin Physics through QCD Instantons
Qian, Yachao
2015-01-01
We review some aspects of spin physics where QCD instantons play an important role. In particular, their large contributions in semi-inclusive deep-inelastic scattering and polarized proton on proton scattering. We also review their possible contribution in the $\\mathcal{P}$-odd pion azimuthal charge correlations in peripheral $AA$ scattering at collider energies.
Spin Correlation in Binary Systems
Farbiash, N; Farbiash, Netzach; Steinitz, Raphael
2004-01-01
We examine the correlation of projected rotational velocities in binary systems. It is an extension of previous work (Steinitz and Pyper, 1970; Levato, 1974). An enlarged data basis and new tests enable us to conclude that there is indeed correlation between the projected rotational velocities of components of binaries. In fact we suggest that spins are already correlated.
Spin Chains and Gustafson's Integrals
Derkachov, S E
2016-01-01
The Gustafson's integrals are the multidimensional generalization of the classical Mellin--Barnes integrals. We show that some of these integrals arise from relations between matrix elements in the Sklyanin's representation of Separated Variables in the spin chain models. We also present several new integrals.
Spin networks for noncompact groups
Freidel, Laurent; Livine, Etera R.
2003-03-01
Spin networks are a natural generalization of Wilson loop functionals. They have been extensively studied in the case where the gauge group is compact and it has been shown that they naturally form a basis of gauge invariant observables. Physically the restriction to compact gauge groups is enough for the study of Yang-Mills theories, however it is well known that noncompact groups naturally arise as internal gauge groups for Lorentzian gravity models. In this context, a proper construction of gauge invariant observables is needed. The purpose of the present work is to define the notion of spin network states for noncompact groups. We first build, by a careful gauge fixing procedure, a natural measure and a Hilbert space structure on the space of gauge invariant graph connections. Spin networks are then defined as generalized eigenvectors of a complete set of hermitic commuting operators. We show how the delicate issue of taking the quotient of a space by noncompact groups can be address in term of algebraic geometry. We finally construct the full Hilbert space containing all spin network states. Having in mind applications to gravity, we illustrate our results for the groups SL(2,R) and SL(2,C).
Spin glasses and neural networks
Energy Technology Data Exchange (ETDEWEB)
Parga, N. (Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche; Universidad Nacional de Cuyo, San Carlos de Bariloche (Argentina). Inst. Balseiro)
1989-07-01
The mean-field theory of spin glass models has been used as a prototype of systems with frustration and disorder. One of the most interesting related systems are models of associative memories. In these lectures we review the main concepts developed to solve the Sherrington-Kirkpatrick model and its application to neural networks. (orig.).
Spin-orbit ferromagnetic resonance
Ferguson, Andrew
2013-03-01
In conventional magnetic resonance techniques the magnitude and direction of the oscillatory magnetic field are (at least approximately) known. This oscillatory field is used to probe the properties of a spin ensemble. Here, I will describe experiments that do the inverse. I will discuss how we use a magnetic resonance technique to map out the current-induced effective magnetic fields in the ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P). These current-induced fields have their origin in the spin-orbit interaction. Effective magnetic fields are observed with symmetries which resemble the Dresselhaus and Rashba spin-orbit interactions and which depend on the diagonal and off-diagonal strain respectively. Ferromagnetic semiconductor materials of different strains, annealing conditions and concentrations are studied and the results compared with theoretical calculations. Our original study measured the rectification voltage coming from the product of the oscillatory magnetoresistance, during magnetisation precession, and the alternating current. More recently we have developed an impedance matching technique which enables us to extract microwave voltages from these high resistance (10 k Ω) samples. In this way we measure the microwave voltage coming from the product of the oscillating magneto-resistance and a direct current. The direct current is observed to affect the magnetisation precession, indicating that anti-damping as well as field-like torques can originate from the spin-orbit interaction.
Rahman, Rakibur
2013-01-01
These notes comprise a part of the introductory lectures on Higher Spin Theory presented in the Eighth Modave Summer School in Mathematical Physics. We construct free higher-spin theories and turn on interactions to find that inconsistencies show up in general. Interacting massless fields in flat space are in tension with gauge invariance and this leads to various no-go theorems. While massive fields exhibit superluminal propagation, appropriate non-minimal terms may cure such pathologies as they do in String Theory -- a fact that we demonstrate. Given that any interacting massive higher-spin particle is described by an effective field theory, we compute a model independent upper bound on the ultraviolet cutoff in the case of electromagnetic coupling in flat space and discuss its implications. Finally, we consider various possibilities of evading the no-go theorems for massless fields, among which Vasiliev's higher-spin gauge theory is one. We work out a simple example of a higher-derivative cubic coupling in...
Spin observables in hyperon production
Maggiora, M; Bedfer, Y; Bertini, R; Bland, L C; Brochard, F; Bussa, M P; Chalyshev, V; Choi, S; Debowski, M; Dzemidzic, M; Faivre, Jean-Claude; Falomkin, I V; Fava, L; Ferrero, L; Foryciarz, J; Frolov, V; Fröhlich, I; Garfagnini, R; Gill, D; Grasso, A; Heinz, S; Ivanov, V V; Jacobs, W W; Kühn, W; Maggiora, A; Manara, A; Panzieri, D; Pfaff, H W; Piragino, G; Pontecorvo, G B; Popov, A; Ritman, J; Salabura, P; Tosello, F; Vigdor, S E; Zosi, G
2000-01-01
The first exclusive measurements of the spin transfer parameter D sub N sub N in the reaction p-vectorp->pK sup +LAMBDA-vector has been performed at Saturne with the polarized beam and with the DISTO spectrometer. The results suggest an OBE mechanism dominated by kaon exchange.
2013-09-01
switches (ITW series 65 model 401000 over travel switch) that inhibit SpinSat from powering up until it is deployed from the Cyclops. These switches...the uplink at about 450 MHz and downlink at about 401 MHz. The transceiver cannot switch between the two frequencies due to the range of the VCO
Direct spinning of fiber supercapacitor.
Xu, Tong; Ding, Xiaoteng; Liang, Yuan; Zhao, Yang; Chen, Nan; Qu, Liangti
2016-06-16
A direct wet spinning approach is demonstrated for facile and continuous fabrication of a whole fiber supercapacitor using a microfluidic spinneret. The resulting fiber supercapacitor shows good electrochemical properties and possesses high flexibility and mechanical stability. This strategy paves the way for large-scale continuous production of fiber supercapacitors for weavable electronics.
Transverse Spin Physics at HERMES
Elschenbroich, U; Seidl, R
2004-01-01
Single-spin asymmetries in semi-inclusive pion production are measured by the HERMES experiment for the first time, with a transversely polarised hydrogen target. Two different sine-dependencies are extracted which can be related to the quark distributions transversity h_1(x) and the Sivers function f_1T^perp(x).
Spin current and polarization in impure two-dimensional electron systems with spin-orbit coupling.
Mishchenko, E G; Shytov, A V; Halperin, B I
2004-11-26
We derive the transport equations for two-dimensional electron systems with Rashba spin-orbit interaction and short-range spin-independent disorder. In the limit of slow spatial variations, we obtain coupled diffusion equations for the electron density and spin. Using these equations we calculate electric-field induced spin accumulation and spin current in a finite-size sample for an arbitrary ratio between spin-orbit energy splitting Delta and elastic scattering rate tau(-1). We demonstrate that the spin-Hall conductivity vanishes in an infinite system independent of this ratio.
Inverse spin Hall effect induced by spin pumping into semiconducting ZnO
Energy Technology Data Exchange (ETDEWEB)
Lee, Jung-Chuan [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Huang, Leng-Wei [Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China); Hung, Dung-Shing, E-mail: dshung@mail.mcu.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Information and Telecommunications Engineering, Ming Chuan University, Taipei 111, Taiwan (China); Chiang, Tung-Han [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Huang, J. C. A., E-mail: jcahuang@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Liang, Jun-Zhi [Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Physics, Fu Jen Catholic University, Taipei 242, Taiwan (China); Lee, Shang-Fan, E-mail: leesf@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China)
2014-02-03
The inverse spin Hall effect (ISHE) of n-type semiconductor ZnO thin films with weak spin-orbit coupling has been observed by utilizing the spin pumping method. In the ferromagnetic resonance condition, the spin pumping driven by the dynamical exchange interaction of a permalloy film injects a pure spin current into the adjacent ZnO layer. This spin current gives rise to a DC voltage through the ISHE in the ZnO layer, and the DC voltage is proportional to the microwave excitation power. The effect is sizeable even when the spin backflow is considered.
Persistent Spin Current in a Quantum Wire with Weak Rashba Spin-Orbit Coupling
Institute of Scientific and Technical Information of China (English)
WANG Yi; SHENG Wei; ZHOU Guang-Hui
2006-01-01
@@ We theoretically investigate the spin current for a parabolically confined semiconductor heterojunction quantum wire with weak Rashba spin-orbit coupling by means of the perturbation method. By analytical calculation, it is found that only two components off spin current density is non-zero in the equilibrium case. Numerical examples have demonstrated that the spin current of electron transverse motion is 10-3 times that off electron longitudinal motion. However, the former one is much more sensitive to the strength of Rashba spin-orbit coupling. These results may suggest an approach to the spin storage device and to the measurement of spin current through its induced electric field.
Geometric Integrators for Classical Spin Systems
Frank, J.E.; Huang, W.; Leimkuhler, B.J.
1997-01-01
Practical, structure-preserving methods for integrating classical Heisenberg spin systems are discussed. Two new integrators are derived and compared, including (1) a symmetric energy and spin-length preserving integrator based on a Red-Black splitting of the spin sites combined with a staggered tim
Simple classical approach to spin resonance phenomena
DEFF Research Database (Denmark)
Gordon, R A
1977-01-01
A simple classical method of describing spin resonance in terms of the average power absorbed by a spin system is discussed. The method has several advantages over more conventional treatments, and a number of important spin resonance phenomena, not normally considered at the introductory level...
Two spinning ways for precession dynamo.
Cappanera, L; Guermond, J-L; Léorat, J; Nore, C
2016-04-01
It is numerically demonstrated by means of a magnetohydrodynamic code that precession can trigger dynamo action in a cylindrical container. Fixing the angle between the spin and the precession axis to be 1/2π, two limit configurations of the spinning axis are explored: either the symmetry axis of the cylinder is parallel to the spin axis (this configuration is henceforth referred to as the axial spin case), or it is perpendicular to the spin axis (this configuration is referred to as the equatorial spin case). In both cases, the centro-symmetry of the flow breaks when the kinetic Reynolds number increases. Equatorial spinning is found to be more efficient in breaking the centro-symmetry of the flow. In both cases, the average flow in the reference frame of the mantle converges to a counter-rotation with respect to the spin axis as the Reynolds number grows. We find a scaling law for the average kinetic energy in term of the Reynolds number in the axial spin case. In the equatorial spin case, the unsteady asymmetric flow is shown to be capable of sustaining dynamo action in the linear and nonlinear regimes. The magnetic field is mainly dipolar in the equatorial spin case, while it is is mainly quadrupolar in the axial spin case.
Gravitational waves and spinning test particles
Mohseni, M
2000-01-01
The motion of a classical spinning test particle in the field of a weak plane gravitational wave is studied. It is found that the characteristic dimensions of the particle's orbit is sensitive to the ratio of the spin to the mass of the particle. The results are compared with the corresponding motion of a particle without spin.
Spinning particles in scalar-tensor gravity
Energy Technology Data Exchange (ETDEWEB)
Burton, D.A. [Department of Physics, Lancaster University (United Kingdom); Cockcroft Institute (United Kingdom)], E-mail: d.burton@lancaster.ac.uk; Tucker, R.W. [Department of Physics, Lancaster University (United Kingdom); Cockcroft Institute (United Kingdom); Wang, C.H. [Department of Physics, National Central University, Taiwan (China)
2008-04-28
We develop a new model of a spinning particle in Brans-Dicke spacetime using a metric-compatible connection with torsion. The particle's spin vector is shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline (an autoparallel of the metric-compatible connection) when neglecting spin-curvature coupling.
Spinning particles in scalar-tensor gravity
Burton, D. A.; Tucker, R. W.; Wang, C. H.
2007-01-01
We develop a new model of a spinning particle in Brans-Dicke spacetime using a metric-compatible connection with torsion. The particle's spin vector is shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline (an autoparallel of the metric-compatible connection) when neglecting spin-curvature coupling.
Spinning particles in scalar-tensor gravity
Burton, D. A.; Tucker, R. W.; Wang, C. H.
2008-04-01
We develop a new model of a spinning particle in Brans-Dicke spacetime using a metric-compatible connection with torsion. The particle's spin vector is shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline (an autoparallel of the metric-compatible connection) when neglecting spin-curvature coupling.
Feynman diagrammatic approach to spin foams
Kisielowski, Marcin; Puchta, Jacek
2011-01-01
"The Spin Foams for People Without the 3d/4d Imagination" could be an alternative title of our work. We derive spin foams from operator spin network diagrams} we introduce. Our diagrams are the spin network analogy of the Feynman diagrams. Their framework is compatible with the framework of Loop Quantum Gravity. For every operator spin network diagram we construct a corresponding operator spin foam. Admitting all the spin networks of LQG and all possible diagrams leads to a clearly defined large class of operator spin foams. In this way our framework provides a proposal for a class of 2-cell complexes that should be used in the spin foam theories of LQG. Within this class, our diagrams are just equivalent to the spin foams. The advantage, however, in the diagram framework is, that it is self contained, all the amplitudes can be calculated directly from the diagrams without explicit visualization of the corresponding spin foams. The spin network diagram operators and amplitudes are consistently defined on thei...
Dressed Quarks and PROTON’S Spin
Yang, Xin-Hua; Wong, Chun Wa; Chu, Keh-Cheng
The effect on the proton spin of mixing gluon and sea quark configurations is studied in a perturbative treatment based on the MIT bag model. As little as 29% of the proton spin is found to remain as the intrinsic spin of quarks when they are “dressed” by gluons.
Observation of the spin Seebeck effect.
Uchida, K; Takahashi, S; Harii, K; Ieda, J; Koshibae, W; Ando, K; Maekawa, S; Saitoh, E
2008-10-09
The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be exploited, for example, in thermal electric-power generators and for temperature sensing, by connecting two conductors with different Seebeck coefficients, a device called a thermocouple. Here we report the observation of the thermal generation of driving power, or voltage, for electron spin: the spin Seebeck effect. Using a recently developed spin-detection technique that involves the spin Hall effect, we measure the spin voltage generated from a temperature gradient in a metallic magnet. This thermally induced spin voltage persists even at distances far from the sample ends, and spins can be extracted from every position on the magnet simply by attaching a metal. The spin Seebeck effect observed here is directly applicable to the production of spin-voltage generators, which are crucial for driving spintronic devices. The spin Seebeck effect allows us to pass a pure spin current, a flow of electron spins without electric currents, over a long distance. These innovative capabilities will invigorate spintronics research.
Energy Technology Data Exchange (ETDEWEB)
Bai,M.; Ptitsyn, V.; Roser, T.
2008-10-01
To keep the spin tune in the spin depolarizing resonance free region is required for accelerating polarized protons to high energy. In RHIC, two snakes are located at the opposite side of each accelerator. They are configured to yield a spin tune of 1/2. Two pairs of spin rotators are located at either side of two detectors in each ring in RHIC to provide longitudinal polarization for the experiments. Since the spin rotation from vertical to longitudinal is localized between the two rotators, the spin rotators do not change the spin tune. However, due to the imperfection of the orbits around the snakes and rotators, the spin tune can be shifted. This note presents the impact of the horizontal orbital angle between the two snakes on the spin tune, as well as the effect of the vertical orbital angle between two rotators at either side of the collision point on the spin tune.
Spin Chern number and topological phase transition on the Lieb lattice with spin-orbit coupling
Chen, Rui; Zhou, Bin
2017-03-01
We propose that quantum anomalous Hall effect may occur in the Lieb lattice, when Rashba spin-orbit coupling, spin-independent and spin-dependent staggered potentials are introduced into the lattice. It is found that spin Chern numbers of two degenerate flat bands change from 0 to ±2 due to Rashba spin-orbit coupling effect. The inclusion of Rashba spin-orbit coupling and two kinds of staggered potentials opens a gap between the two flat bands. The topological property of the gap is determined by the amplitudes of Rashba spin-orbit coupling and staggered potentials, and thus the topological phase transition from quantum anomalous Hall effect to normal insulator can occur. Finally, the topological phase transition from quantum spin Hall state to normal insulator is discussed when Rashba spin-orbit coupling and intrinsic spin-orbit coupling coexist in the Lieb lattice.
Singh, Simranjeet; Katoch, Jyoti; Xu, Jinsong; Tan, Cheng; Zhu, Tiancong; Amamou, Walid; Hone, James; Kawakami, Roland
2016-09-01
We present an experimental study of spin transport in single layer graphene using atomic sheets of hexagonal boron nitride (h-BN) as a tunnel barrier for spin injection. While h-BN is expected to be favorable for spin injection, previous experimental studies have been unable to achieve spin relaxation times in the nanosecond regime, suggesting potential problems originating from the contacts. Here, we investigate spin relaxation in graphene spin valves with h-BN barriers and observe room temperature spin lifetimes in excess of a nanosecond, which provides experimental confirmation that h-BN is indeed a good barrier material for spin injection into graphene. By carrying out measurements with different thicknesses of h-BN, we show that few layer h-BN is a better choice than monolayer for achieving high non-local spin signals and longer spin relaxation times in graphene.
Spin transport through quantum dots
Energy Technology Data Exchange (ETDEWEB)
Lima, A.T. da Cunha; Anda, Enrique V. [Pontificia Univ. Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil)
2003-07-01
Full text: We investigate the spin polarized transport properties of a nanoscopic device constituted by a quantum dot connected to two leads. The electrical current circulates with a spin polarization that is modulated via a gate potential that controls the intensity of the spin-orbit coupling, the Rashba effect. We study a polarized field-effect transistor when one of its parts is constituted by a small quantum dot, which energies are controlled by another gate potential operating inside the confined region. The high confinement and correlation suffered by the charges inside the dot gives rise to novel phenomena. We show that through the manipulation of the gate potential applied to the dot it is possible to control, in a very efficient way, the intensity and polarization of the current that goes along the system. Other crucial parameters to be varied in order to understand the behavior of this system are the intensity of the external applied electric and magnetic field. The system is represented by the Anderson Impurity Hamiltonian summed to a spin-orbit interaction, which describes the Rashba effect. To obtain the current of this out-of-equilibrium system we use the Keldysh formalism.The solution of the Green function are compatible with the Coulomb blockade regime. We show that under the effect of a external magnetic field, if the dot is small enough the device operates as a complete spin filter that can be controlled by the gate potential. The behavior of this device when it is injected into it a polarized current and modulated by the Rashba effect is as well studied. (author)
Spin injection in spin FETs using a step-doping profile
Shen, Min; Saikin, Semion; Cheng, Ming-Cheng
2004-01-01
We investigate effect of a step-doping profile on the spin injection from a ferromagnetic metal contact into a semiconductor quantum well (QW) in spin FETs using a Monte Carlo model. The considered scheme uses a heavily doped layer at the metal/semiconductor interface to vary the Schottky barrier shape and enhance the tunneling current. It is found that spin flux (spin current density) is enhanced proportionally to the total current, and the variation of current spin polarization does not exc...
Persistent spin current in nano-devices and definition of the spin current
Sun, Qing-feng; Xie, X. C.; WANG Jian
2008-01-01
We investigate two closely related subjects: (i) existence of a pure persistent spin current in semiconducting mesoscopic device with a spin-orbit interaction's (SOI), and (ii) the definition of the spin current in the presence of SOI. Through physical argument from four physical pictures in different aspects, we provide strong evidences that the persistent spin current does exist in a device with SOI in the absence of any magnetic materials. This persistent spin current is an analog of the p...
Thermal spin pumping and magnon-phonon-mediated spin-Seebeck effect
Uchida, K.; Ota, T.; Adachi, H; Xiao, J.; Nonaka, T.; Kajiwara, Y; Bauer, G. E. W.; Maekawa, S.; Saitoh, E.
2011-01-01
The spin-Seebeck effect (SSE) in ferromagnetic metals and insulators has been investigated systematically by means of the inverse spin-Hall effect (ISHE) in paramagnetic metals. The SSE generates a spin voltage as a result of a temperature gradient in a ferromagnet, which injects a spin current into an attached paramagnetic metal. In the paramagnet, this spin current is converted into an electric field due to the ISHE, enabling the electric detection of the SSE. The observation of the SSE is ...
Comparative aspects of spin-dependent interaction potentials for spin-1/2 and spin-1 matter fields
Malta, P C; Veiga, K; Helayël-Neto, J A
2015-01-01
This paper sets out to establish a comparative study between classes of spin- and velocity-dependent current-current interaction potentials for spin-1/2 and spin-1 matter sources in the non-relativistic regime. Both (neutral massive) scalar and vector particles are considered to mediate the interactions between scalar, pseudo-scalar, vector and pseudo-vector matter currents. 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 to the comparison between 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.
Nonlocal Spin Diffusion Driven by Giant Spin Hall Effect at Oxide Heterointerfaces.
Jin, Mi-Jin; Moon, Seon Young; Park, Jungmin; Modepalli, Vijayakumar; Jo, Junhyeon; Kim, Shin-Ik; Koo, Hyun Cheol; Min, Byoung-Chul; Lee, Hyun-Woo; Baek, Seung-Hyub; Yoo, Jung-Woo
2017-01-11
A two-dimensional electron gas emerged at a LaAlO3/SrTiO3 interface is an ideal system for "spin-orbitronics" as the structure itself strongly couple the spin and orbital degree of freedom through the Rashba spin-orbit interaction. One of core experiments toward this direction is the nonlocal spin transport measurement, which has remained elusive due to the low spin injection efficiency to this system. Here we bypass the problem by generating a spin current not through the spin injection from outside but instead through the inherent spin Hall effect and demonstrate the nonlocal spin transport. The analysis on the nonlocal spin voltage, confirmed by the signature of a Larmor spin precession and its length dependence, displays that both D'yakonov-Perel' and Elliott-Yafet mechanisms involve in the spin relaxation at low temperature. Our results show that the oxide heterointerface is highly efficient in spin-charge conversion with exceptionally strong spin Hall coefficient γ ∼ 0.15 ± 0.05 and could be an outstanding platform for the study of coupled charge and spin transport phenomena and their electronic applications.
Electrical detection of spin coherence in silicon.
Boehme, Christoph; Lips, Klaus
2003-12-12
Experimental evidence is presented showing that photocurrents in silicon can be used as highly sensitive readout probes for coherent spin states of localized electrons, the prime candidates for quantum bits in various semiconductor based quantum computer concepts. Conduction electrons are subjected to fast Rabi oscillation induced by means of pulsed electron spin resonance. The collective spin motion of the charge carrier ensemble is reflected by a spin-dependent recombination rate and therefore by the sample conductivity. Because of inhomogeneities, the Rabi oscillation dephases rapidly. However, a microwave induced rephasing is possible causing an echo effect whose intensity contains information about the charge carrier spin state and the coherence decay.
Thermodynamics of strongly disordered spin ladders
Yusuf, Eddy; Yang, Kun
2002-01-01
We study antiferromagnetic two-leg spin-1/2 ladders with strong bond randomness, using the real space renormalization group method. We find the low-temperature spin susceptibility of the system follows non-universal power laws, and the ground state spin-spin correlation is short-ranged. Our results suggest that there is no phase transition when the bond randomness increases from zero; for strong enough randomness the system is in a Griffith region with divergent spin susceptibility and short-...
Superadiabatic quantum state transfer in spin chains
Agundez, R. R.; Hill, C. D.; Hollenberg, L. C. L.; Rogge, S.; Blaauboer, M.
2017-01-01
In this paper we propose a superadiabatic protocol where quantum state transfer can be achieved with arbitrarily high accuracy and minimal control across long spin chains with an odd number of spins. The quantum state transfer protocol only requires the control of the couplings between the qubits on the edge and the spin chain. We predict fidelities above 0.99 for an evolution of nanoseconds using typical spin-exchange coupling values of μ eV . Furthermore, by building a superadiabatic formalism on top of this protocol, we propose an effective superadiabatic protocol that retains the minimal control over the spin chain and further improves the fidelity.
Reconfigurable heat-induced spin wave lenses
Dzyapko, O.; Borisenko, I. V.; Demidov, V. E.; Pernice, W.; Demokritov, S. O.
2016-12-01
We study the control and manipulation of propagating spin waves in yttrium iron garnet films using a local laser-induced heating. We show that, due to the refraction of spin waves in the thermal gradients, the heated region acts as a defocusing lens for Damon-Eshbach spin waves and as a focusing lens for backward volume waves enabling collimation of spin-wave beams in the latter case. In addition to the focusing/defocusing functionality, the local heating allows one to manipulate the propagation direction of the spin-wave beams and to efficiently suppress their diffraction spreading by utilizing caustic effects.
Leviatan, A
2000-01-01
We use the empirical evidence that F-spin multiplets exist in nuclei for only selected states as an indication that F spin can be regarded as a partial symmetry. We show that there is a class of non-F-scalar IBM-2 Hamiltonians with partial F-spin symmetry, which reproduce the known systematics of collective bands in nuclei. These Hamiltonians predict that the scissors states have good F-spin and form F-spin multiplets, which is supported by the existing data. (22 refs).
Leviatan, A
2000-01-01
We use the empirical evidence that F-spin multiplets exist in nuclei for only selected states as an indication that F-spin can be regarded as a partial symmetry. We show that there is a class of non-F-scalar IBM-2 Hamiltonians with partial F-spin symmetry, which reproduce the known systematics of collective bands in nuclei. These Hamiltonians predict that the scissors states have good F-spin and form F-spin multiplets, which is supported by the existing data.
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904, (Israel); Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Institute for Nuclear Theory, University of Washington, Box 351550, Seattle, Washington 98195 (United States); Ginocchio, J. N. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2000-02-01
We use the empirical evidence that F-spin multiplets exist in nuclei for only selected states as an indication that F spin can be regarded as a partial symmetry. We show that there is a class of non-F-scalar IBM-2 Hamiltonians with partial F-spin symmetry, which reproduce the known systematics of collective bands in nuclei. These Hamiltonians predict that the scissors states have good F-spin and form F-spin multiplets, which is supported by the existing data. (c) 2000 The American Physical Society.
Spin, Isospin and Strong Interaction Dynamics
Directory of Open Access Journals (Sweden)
Comay E.
2011-10-01
Full Text Available The structure of spin and isospin is analyzed. Although both spin and isospin are related to the same SU(2 group, they represent different dynamical effects. The Wigner-Racah algebra is used for providing a description of bound states of several Dirac particles in general and of the proton state in particular. Isospin states of the four ∆ (1232 baryons are discussed. The work explains the small contribution of quarks spin to the overall proton spin (the proton spin crisis. It is also proved that the addition of QCD’s color is not required for a construction of an antisymmetric state for the ∆ ++ (1232 baryon.
Spin Particle in an Absorbing Environment
Amooshahi, M.
2015-10-01
The quantum dynamics of a localized spin Particle interacting with an absorbing environment is investigated. The quantum Langevin-Schrödinger equation for spin is obtained. The susceptibility function of the environment is calculated in terms of the coupling function of the spin and the environment. it is shown that the susceptibility function satisfies the Kramers-Kronig relations. Spontaneous emission and the shift frequency of the spin is obtained in terms of the imaginary part of the susceptibility function in frequency domain. Some transition probabilities between the spin states are calculated when the absorbing environment is in the thermal state.
Nonequilibrium thermodynamics of the spin Seebeck and spin Peltier effects
Basso, Vittorio; Ferraro, Elena; Magni, Alessandro; Sola, Alessandro; Kuepferling, Michaela; Pasquale, Massimo
2016-05-01
We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and spin Peltier effects. By focusing on the specific geometry with one Y3Fe5O12 (YIG) layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length lM˜0.4 μ m and the absolute thermomagnetic power coefficient ɛM˜10-2TK-1 .
Spin supersolid in an anisotropic spin-one Heisenberg chain.
Sengupta, P; Batista, C D
2007-11-23
We consider an S=1 Heisenberg chain with strong exchange (Delta=J(z)/J(perpendicular)) and single-ion uniaxial anisotropy (D) in a magnetic field (B) along the symmetry axis. The low-energy spectrum is described by an effective S=1/2 XXZ model that acts on two different low-energy sectors for a finite range of fields. The vacuum of each sector exhibits Ising-like antiferromagnetic ordering coexisting with the finite spin stiffness obtained from the exact solution of the XXZ model. In this way, we demonstrate the existence of a spin supersolid phase. We also compute the full Delta-B quantum phase diagram using a quantum Monte Carlo method.
Chaotic spin-spin entanglement on a recursive lattice.
Chakhmakhchyan, Levon; Guérin, Stéphane; Leroy, Claude
2015-08-01
We propose an exactly solvable multisite interaction spin-1/2 Ising-Heisenberg model on a triangulated Husimi lattice for the rigorous studies of chaotic entanglement. By making use of the generalized star-triangle transformation, we map the initial model onto an effective Ising one on a Husimi lattice, which we solve then exactly by applying the recursive method. Expressing the entanglement of the Heisenberg spins, that we quantify by means of the concurrence, in terms of the magnetic quantities of the system, we demonstrate its bifurcation and chaotic behavior. Furthermore, we show that the underlying chaos may slightly enhance the amount of the entanglement and present on the phase diagram the transition lines from the uniform to periodic and from the periodic to chaotic regimes.
Spin-Spin Coupling in the Solar System
Batygin, Konstantin
2015-01-01
The richness of dynamical behavior exhibited by the rotational states of various solar system objects has driven significant advances in the theoretical understanding of their evolutionary histories. An important factor that determines whether a given object is prone to exhibiting non-trivial rotational evolution is the extent to which such an object can maintain a permanent aspheroidal shape, meaning that exotic behavior is far more common among the small body populations of the solar system. Gravitationally bound binary objects constitute a substantial fraction of asteroidal and TNO populations, comprising systems of triaxial satellites that orbit permanently deformed central bodies. In this work, we explore the rotational evolution of such systems with specific emphasis on quadrupole-quadrupole interactions, and show that for closely orbiting, highly deformed objects, both prograde and retrograde spin-spin resonances naturally arise. Subsequently, we derive capture probabilities for leading order commensur...
Electric probe for spin transition and fluctuation
Qiu, Zhiyong; Li, Jia; Hou, Dazhi; Arenholz, Elke; N'diaye, Alpha T.; Tan, Ali; Uchida, Ken-Ichi; Sato, Koji; Tserkovnyak, Yaroslov; Qiu, Z. Q.; Saitoh, Eiji
Spin fluctuation and transition have always been one of central topics of magnetism and condense matter science. To probe them, neutron scatterings have been used as powerful tools. A part of neutrons injected into a sample is scattered by spin fluctuation inside the sample. This process transcribes the spin fluctuation onto scattering intensity, which is commonly represented by dynamical magnetic susceptibility of the sample and is maximized at magnetic phase transitions. Importantly, a neutron carries spin without electric charge, and it thus can bring spin into a sample without being disturbed by electric energy: an advantage of neutrons, although large facilities such as a nuclear reactor is necessary. Here we show that spin pumping, frequently used in nanoscale spintronic devices, provides a desktop micro probe for spin fluctuation and transition; not only a neutron beam, spin current is also a flux of spin without an electric charge and its transport reflects spin fluctuation in a sample. We demonstrate detection of anti-ferromagnetic transition in ultra-thin CoO films via frequency dependent spin-current transmission measurements.
Spin-crossover molecule based thermoelectric junction
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Dibyajyoti [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Parida, Prakash [Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg (Germany); Pati, Swapan K. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)
2015-05-11
Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.
Free spin quantum computation with semiconductor nanostructures
Zhang, W M; Soo, C; Zhang, Wei-Min; Wu, Yin-Zhong; Soo, Chopin
2005-01-01
Taking the excess electron spin in a unit cell of semiconductor multiple quantum-dot structure as a qubit, we can implement scalable quantum computation without resorting to spin-spin interactions. The technique of single electron tunnelings and the structure of quantum-dot cellular automata (QCA) are used to create a charge entangled state of two electrons which is then converted into spin entanglement states by using single spin rotations. Deterministic two-qubit quantum gates can also be manipulated using only single spin rotations with help of QCA. A single-short read-out of spin states can be realized by coupling the unit cell to a quantum point contact.
The Spin Structure of the Proton
Ma, B Q
2000-01-01
It is shown that the proton "spin crisis'' or "spin puzzle" can be understood by the relativistic effect of quark transversal motions due to the Melosh-Wigner rotation. The quark helicity $\\Delta q$ measured in polarized deep inelastic scattering is actually the quark spin in the infinite momentum frame or in the light-cone formalism, and it is different from the quark spin in the nucleon rest frame or in the quark model. The flavor asymmetry of the Melosh-Wigner effect for the valence $u$ and $d$ quarks and the intrinsic sea $q \\bar{q}$ pairs are also the important ingredients in a SU(6) quark-spectator-diquark model framework to understand the "spin puzzle". Such a picture of the spin structure can be tested by use of several simple relations to measure the quark spin distributions in the quark model.
Thermal imaging of spin Peltier effect
Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-Ichi
2016-12-01
The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The `spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed.
Prospects for Neutrino Spin Coherence in Supernovae
Tian, James
2016-01-01
We present neutrino bulb model simulations of majorana neutrino coherent spin transformation (i.e., neutrino-antineutrino transformation) for conditions corresponding to the neutronization burst epoch of an O-Ne-Mg core collapse supernova. Significant neutrino spin transformation, in e.g. the neutronization burst, could alter the fluence of neutrinos and antineutrinos in a way which is potentially detectable for a galactic core collapse supernova. Our calculations for the first time treat geometric dilution in the spin evolution of the neutrinos and combine two-flavor and three-flavor neutrino flavor evolution with spin mixing physics. We find that significant spin transformations can occur, but only with an electron fraction profile which facilitates adiabatic conditions for the spin-channel resonance. Using our adopted parameters of neutrino energy spectra, luminosity, density and electron fraction profiles, our calculations require an unrealistically large neutrino rest mass to sustain the spin transformat...
Charge and spin transport in mesoscopic superconductors
Directory of Open Access Journals (Sweden)
M. J. Wolf
2014-02-01
Full Text Available Background: Non-equilibrium charge transport in superconductors has been investigated intensely in the 1970s and 1980s, mostly in the vicinity of the critical temperature. Much less attention has been paid to low temperatures and the role of the quasiparticle spin.Results: We report here on nonlocal transport in superconductor hybrid structures at very low temperatures. By comparing the nonlocal conductance obtained by using ferromagnetic and normal-metal detectors, we discriminate charge and spin degrees of freedom. We observe spin injection and long-range transport of pure, chargeless spin currents in the regime of large Zeeman splitting. We elucidate charge and spin transport by comparison to theoretical models.Conclusion: The observed long-range chargeless spin transport opens a new path to manipulate and utilize the quasiparticle spin in superconductor nanostructures.
High spin isomer beam line at RIKEN
Energy Technology Data Exchange (ETDEWEB)
Kishida, T.; Ideguchi, E.; Wu, H.Y. [Institute of Physical and Chemical Research, Saitama (Japan)] [and others
1996-12-31
Nuclear high spin states have been the subject of extensive experimental and theoretical studies. For the production of high spin states, fusion reactions are usually used. The orbital angular momentum brought in the reaction is changed into the nuclear spin of the compound nucleus. However, the maximum induced angular momentum is limited in this mechanism by the maximum impact parameter of the fusion reaction and by the competition with fission reactions. It is, therefore, difficult to populate very high spin states, and as a result, large {gamma}-detector arrays have been developed in order to detect subtle signals from such very high spin states. The use of high spin isomers in the fusion reactions can break this limitation because the high spin isomers have their intrinsic angular momentum, which can bring the additional angular momentum without increasing the excitation energy. There are two methods to use the high spin isomers for secondary reactions: the use of the high spin isomers as a target and that as a beam. A high spin isomer target has already been developed and used for several experiments. But this method has an inevitable shortcoming that only {open_quotes}long-lived{close_quotes} isomers can be used for a target: {sup 178}Hf{sup m2} (16{sup +}) with a half-life of 31 years in the present case. By developing a high spin isomer beam, the authors can utilize various short-lived isomers with a short half-life around 1 {mu}s. The high spin isomer beam line of RIKEN Accelerator Facility is a unique apparatus in the world which provides a high spin isomer as a secondary beam. The combination of fusion-evaporation reaction and inverse kinematics are used to produce high spin isomer beams; in particular, the adoption of `inverse kinematics` is essential to use short-lived isomers as a beam.
Nonreciprocal Transverse Photonic Spin and Magnetization-Induced Electromagnetic Spin-Orbit Coupling
Levy, Miguel; Karki, Dolendra
2017-01-01
We present a formulation of electromagnetic spin-orbit coupling in magneto-optic media, and propose an alternative source of spin-orbit coupling to non-paraxial optics vortices. Our treatment puts forth a formulation of nonreciprocal transverse-spin angular-momentum-density shifts for evanescent waves in magneto-optic waveguide media. It shows that magnetization-induced electromagnetic spin-orbit coupling is possible, and that it leads to unequal spin to orbital angular momentum conversion in magneto-optic media evanescent waves in opposite propagation-directions. Generation of free-space helicoidal beams based on this conversion is shown to be spin-helicity- and magnetization-dependent. We show that transverse-spin to orbital angular momentum coupling into magneto-optic waveguide media engenders spin-helicity-dependent unidirectional propagation. This unidirectional effect produces different orbital angular momenta in opposite directions upon excitation-spin-helicity reversals.
Hojem, A.; Wesenberg, D.; Zink, B. L.
2016-07-01
We present measurements of thermal and electrical spin injection in nanoscale metallic nonlocal spin valve structures. Informed by measurements of the Seebeck coefficient and thermal conductivity of representative films made using a micromachined Si-N thermal isolation platform, we use simple analytical and finite-element thermal models to determine limits on the thermal gradient driving thermal spin injection and calculate the spin-dependent Seebeck coefficient to be -0.5 μ V /K >Ss>-1.6 μ V /K . This is comparable in terms of the fraction of the absolute Seebeck coefficient to previous results, despite dramatically smaller electrical spin injection signals. Since the small electrical spin signals are likely caused by interfacial effects, we conclude that thermal spin injection is less sensitive to the ferromagnetic/nonmagnetic interface, and possibly benefits from the presence of oxidized ferromagnets, which further stimulates interest in thermal spin injection for applications in sensors and pure spin current sources.
Dynamical picture of spin Hall effect based on quantum spin vorticity theory
Directory of Open Access Journals (Sweden)
Masahiro Fukuda
2016-02-01
Full Text Available It is proposed that the dynamical picture of the spin Hall effect can be explained as the generation of the spin vorticity by the applied electric field on the basis of the “quantum spin vorticity theory”, which describes the equation of motion of local spin and the vorticity of spin in the framework of quantum field theory. Similarly, it is proposed that the dynamical picture of the inverse spin Hall effect can be explained as the acceleration of the electron by the rotation of the spin torque density as driving force accompanying the generation of the spin vorticity. These explanations may help us to understand spin phenomena in condensed matter and molecular systems from a unified viewpoint.
Jain, Abhinav; Rojas-Sanchez, Juan-Carlos; Cubukcu, Murat; Peiro, Julian; Le Breton, Jean-Christophe; Vergnaud, Céline; Augendre, Emmanuel; Vila, Laurent; Attané, Jean-Philippe; Gambarelli, Serge; Jaffrès, Henri; George, Jean-Marie; Jamet, Matthieu
2013-04-01
Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the electrical spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. Here we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Si and n-Ge using a CoFeB/MgO tunnel contact. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from approximately 150 K up to room temperature. In this regime, the spin signal is reduced down to a value compatible with the standard spin diffusion model. More interestingly, in the case of germanium, we demonstrate a significant modulation of the spin signal by applying a back-gate voltage to the conduction channel. We also observe the inverse spin Hall effect in Ge by spin pumping from the CoFeB electrode. Both observations are consistent with spin accumulation in the Ge conduction band.
Toward spinning artificial spider silk.
Rising, Anna; Johansson, Jan
2015-05-01
Spider silk is strong and extensible but still biodegradable and well tolerated when implanted, making it the ultimate biomaterial. Shortcomings that arise in replicating spider silk are due to the use of recombinant spider silk proteins (spidroins) that lack native domains, the use of denaturing conditions under purification and spinning and the fact that the understanding of how spiders control silk formation is incomplete. Recent progress has unraveled the molecular mechanisms of the spidroin N- and C-terminal nonrepetitive domains (NTs and CTs) and revealed the pH and ion gradients in spiders' silk glands, clarifying how spidroin solubility is maintained and how silk is formed in a fraction of a second. Protons and CO2, generated by carbonic anhydrase, affect the stability and structures of the NT and CT in different ways. These insights should allow the design of conditions and devices for the spinning of recombinant spidroins into native-like silk.
Baillie, C F; Kownacki, J P
1994-01-01
The Ising model on ``thin'' graphs (standard Feynman diagrams) displays several interesting properties. For ferromagnetic couplings there is a mean field phase transition at the corresponding Bethe lattice transition point. For antiferromagnetic couplings the replica trick gives some evidence for a spin glass phase. In this paper we investigate both the ferromagnetic and antiferromagnetic models with the aid of simulations. We confirm the Bethe lattice values of the critical points for the ferromagnetic model on \\phi^3 and \\phi^4 graphs and examine the putative spin glass phase in the antiferromagnetic model by looking at the overlap between replicas in a quenched ensemble of graphs. We also compare the Ising results with those for higher state Potts models and Ising models on ``fat'' graphs, such as those used in 2D gravity simulations.
Spin chains and string theory.
Kruczenski, Martin
2004-10-15
Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit.
Spin physics highlights from STAR
Directory of Open Access Journals (Sweden)
Gibson A.
2015-01-01
Full Text Available As the world’s only polarized proton collider, the Relativistic Heavy Ion Collider (RHIC at Brookhaven plays an important role in understanding the spin structure of the proton. The STAR detector, with its large acceptance for calorimetry and tracking, has been used to study polarized proton collisions for more than a decade with a range of jet, meson, and boson probes. We will discuss jets, neutral pions, and W bosons as probes of the proton’s helicity structure. Here STAR measurements have significant impact on global fits of sea quark polarizations and have provided the first firm evidence of non-zero gluon polarization within the proton. We will discuss W/Z bosons, jets, pions, and pion-jet correlations as probes of the transverse spin structure of the proton, and we will use the example of a proposed dijet measurement with an upgraded STAR detector to peer into the future.
ENHANCING PROFITABILITY OF A SPINNING
Directory of Open Access Journals (Sweden)
MARSAL Feliu
2014-05-01
Full Text Available Systematic control of the rheological behavior of the ravings in an installation facility dynamometer constant elongation gradient is proposed in this paper. It is an application for all types of spinning both shortfibers as long fibers. Industrial experiments conducted show that this control drawing of the spinning frame is optimized, getting more regular yarns mass with greater industrial profitability. This work is applied to a spinning worsted manufactures fine yarns with high quality requirement The fundamental thesis of our work is that the rheological control of the roving, output from roving frame, either torsional or friction, helps to increase the profitability of the spinning frame and get higher quality yarns. Rheology is the science of movement of the fibers within a fibrous vein, is a sliver or roving from the graph tribocharging-elongation another fundamental concept appears in our analysis: the isocarric elongation. Empirically, we defined this elongation as the difference between the elongation percentage corresponding to half the determined maximum tribocharge on the ascending and descending branches of the tribo-charging elongation curve. The application of these techniques to former machines to roving frame in conventional wool process also allows us to adjust the machines with more speed, reducing the time and product (waste required a change in manufacturing. To increase, for example, the feed of a gill, increase the difficult y for drafting in the following step. These difficulties are directly related to the value of the doubling and drafting that applies: the more doubling and drafting, the greater the difficulty in later steps.
Interfering with the neutron spin
Indian Academy of Sciences (India)
Apoorva G Wagh; Veer Chand Rakhecha
2004-07-01
Charge neutrality, a spin $\\dfrac{1}{2}$ and an associated magnetic moment of the neutron make it an ideal probe of quantal spinor evolutions. Polarized neutron interferometry in magnetic field Hamiltonians has thus scored several firsts such as direct verification of Pauli anticommutation, experimental separation of geometric and dynamical phases and observation of non-cyclic amplitudes and phases. This paper provides a flavour of the physics learnt from such experiments.
Demand Response Spinning Reserve Demonstration
Energy Technology Data Exchange (ETDEWEB)
Eto, Joseph H.; Nelson-Hoffman, Janine; Torres, Carlos; Hirth,Scott; Yinger, Bob; Kueck, John; Kirby, Brendan; Bernier, Clark; Wright,Roger; Barat, A.; Watson, David S.
2007-05-01
The Demand Response Spinning Reserve project is a pioneeringdemonstration of how existing utility load-management assets can providean important electricity system reliability resource known as spinningreserve. Using aggregated demand-side resources to provide spinningreserve will give grid operators at the California Independent SystemOperator (CAISO) and Southern California Edison (SCE) a powerful, newtool to improve system reliability, prevent rolling blackouts, and lowersystem operating costs.
Maurand, R.; Jehl, X.; Kotekar-Patil, D.; Corna, A.; Bohuslavskyi, H.; Laviéville, R.; Hutin, L.; Barraud, S.; Vinet, M.; Sanquer, M.; de Franceschi, S.
2016-11-01
Silicon, the main constituent of microprocessor chips, is emerging as a promising material for the realization of future quantum processors. Leveraging its well-established complementary metal-oxide-semiconductor (CMOS) technology would be a clear asset to the development of scalable quantum computing architectures and to their co-integration with classical control hardware. Here we report a silicon quantum bit (qubit) device made with an industry-standard fabrication process. The device consists of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot encoding a hole spin qubit, the second one a quantum dot used for the qubit read-out. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate. The demonstrated qubit functionality in a basic transistor-like device constitutes a promising step towards the elaboration of scalable spin qubit geometries in a readily exploitable CMOS platform.
On higher spin partition functions
Beccaria, M
2015-01-01
We observe that the partition function of the set of all free massless higher spins s=0,1,2,3,... in flat space is equal to one: the ghost determinants cancel against the "physical" ones or, equivalently, the (regularized) total number of degrees of freedom vanishes. This reflects large underlying gauge symmetry and suggests analogy with supersymmetric or topological theory. The Z=1 property extends also to the AdS background, i.e. the 1-loop vacuum partition function of Vasiliev theory is equal to 1 (assuming a particular regularization of the sum over spins); this was noticed earlier as a consistency requirement for the vectorial AdS/CFT duality. We find that Z=1 is also true in the conformal higher spin theory (with higher-derivative d^{2s} kinetic terms) expanded near flat or conformally flat S^4 background. We also consider the partition function of free conformal theory of symmetric traceless rank s tensor field which has 2-derivative kinetic term but only scalar gauge invariance in flat space. This non...
Persistent spin current in a quantum wire with weak Dresselhaus spin-orbit coupling
Institute of Scientific and Technical Information of China (English)
Sheng Wei; Wang Yi; Zhou Guang-Hui
2007-01-01
The spin current in a parabolically confined semiconductor heterojunction quantum wire with Dresselhaus spinorbit coupling is theoretically studied by using the perturbation method. The formulae of the elements for linear and angular spin current densities are derived by using the recent definition for spin current based on spin continuity equation. It is found that the spin current in this Dresselhaus spin-orbit coupling quantum wire is antisymmetrical,which is different from that in R ashba model due to the difference in symmetry between these two models. Some numerical examples for the result are also demonstrated and discussed.
Directory of Open Access Journals (Sweden)
Marco Finazzi
2016-11-01
Full Text Available In this work we address optical orientation, a process consisting in the excitation of spin polarized electrons across the gap of a semiconductor. We show that the combination of optical orientation with spin-dependent scattering leading to the inverse spin-Hall effect, i.e., to the conversion of a spin current into an electrical signal, represents a powerful tool to generate and detect spin currents in solids. We consider a few examples where these two phenomena together allow addressing the spin-dependent transport properties across homogeneous samples or metal/semiconductor Schottky junctions.
Spin-torque switching of a nano-magnet using giant spin hall effect
Directory of Open Access Journals (Sweden)
Ashish V. Penumatcha
2015-10-01
Full Text Available The Giant Spin Hall Effect(GSHE in metals with high spin-orbit coupling is an efficient way to convert charge currents to spin currents, making it well-suited for writing information into magnets in non-volatile magnetic memory as well as spin-logic devices. We demonstrate the switching of an in-plane CoFeB magnet using a combination of GSHE and an external magnetic field. The magnetic field dependence of the critical current is used to estimate the spin hall angle with the help of a thermal activation model for spin-transfer torque switching of a nanomagnet.
Spin torque on the surface of graphene in the presence of spin orbit splitting
Directory of Open Access Journals (Sweden)
Ji Chen
2013-06-01
Full Text Available We study theoretically the spin transfer torque of a ferromagnetic layer coupled to (deposited onto a graphene surface in the presence of the Rashba spin orbit coupling (RSOC. We show that the RSOC induces an effective magnetic field, which will result in the spin precession of conduction electrons. We derive correspondingly the generalized Landau-Lifshitz-Gilbert (LLG equation, which describes the precessional motion of local magnetization under the influence of the spin orbit effect. Our theoretical estimate indicates that the spin orbit spin torque may have significant effect on the magnetization dynamics of the ferromagnetic layer coupled to the graphene surface.
Spin-orbit coupling, spin currents and emergent gauge fields in solids
Energy Technology Data Exchange (ETDEWEB)
Sa, Debanand [Department of Physics, Banaras Hindu University, Varanasi -221005 (India)
2012-07-23
The role of spin-orbit interaction has been exploited to construct an emergent gauge theory in solids. It has been shown that the charge and spin currents in such a solid form a SU(2) Multiplication-Sign U(1) gauge theory. The lack of gauge symmetry in the SU(2) sector and as a consequence, the non-conservation of spin is spelled out. The phenomenon of spin motive force and spin Hall effect is discussed. The importance of such force in the mesoscopic transport as well as Aharonov-Casher effect is outlined. It is shown that the spin currents in such a theory become the source of electric field.
Spin-orbit coupling, spin currents and emergent gauge fields in solids
Sa, Debanand
2012-07-01
The role of spin-orbit interaction has been exploited to construct an emergent gauge theory in solids. It has been shown that the charge and spin currents in such a solid form a SU(2)×U(1) gauge theory. The lack of gauge symmetry in the SU(2) sector and as a consequence, the non-conservation of spin is spelled out. The phenomenon of spin motive force and spin Hall effect is discussed. The importance of such force in the mesoscopic transport as well as Aharonov-Casher effect is outlined. It is shown that the spin currents in such a theory become the source of electric field.
Numerical simulation study on spin resonant depolarization due to spin-orbit coupling
Institute of Scientific and Technical Information of China (English)
Lan Jie-Qin; Xu Hong-Liang
2012-01-01
The spin polarization phenomenon in lepton circular accelerators had been known for many years.It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orbit coupling,such as spin resonances.We use numerical simulation to study the features of spin under the modulation of orbital motion in an electron storage ring.The various cases of depolarization due to spin-orbit coupling through an emitting photon and misalignment of magnets in the ring are discussed.
Interfacial spin Hall current in a Josephson junction with Rashba spin-orbit coupling
Institute of Scientific and Technical Information of China (English)
Yang Zhi-Hong; Yang Yong-Hong; Wang Jun
2012-01-01
We theoretically investigate the spin transport properties of the Cooper pairs in a conventional Josephson junction with Rashba spin orbit coupling considered in one of the superconducting leads.It is found that an angle-resolved spin supercurrent flows through the junction and a nonzero interfacial spin Hall current driven by the superconducting phase difference also appears at the interface.The physical origin of this is that the Rashba spin-orbit coupling can indnce a triplet order parameter in the s-wave superconductor.The interfacial spin Hall current dependences on the system parameters are also discussed.
Room temperature spin relaxation length in spin light-emitting diodes
Soldat, Henning; Li, Mingyuan; Gerhardt, Nils C.; Hofmann, Martin R.; Ludwig, Arne; Ebbing, Astrid; Reuter, Dirk; Wieck, Andreas D.; Stromberg, Frank; Keune, Werner; Wende, Heiko
2011-08-01
We investigate the spin relaxation length in GaAs spin light-emitting diode devices under drift transport at room temperature. The spin-polarised electrons are injected through a MgO tunnel barrier from a Fe/Tb multilayer in magnetic remanence. The decrease in circular polarization with increasing injection path length is investigated and found to be exponential, supporting drift-based transport. The spin relaxation length in our samples is 26 nm, and a lower bound for the spin injection efficiency at the spin injector/GaAs interface is estimated to be 25 ± 2%.
Fourier transform ion cyclotron resonance mass spectrometry: a primer.
Marshall, A G; Hendrickson, C L; Jackson, G S
1998-01-01
This review offers an introduction to the principles and generic applications of FT-ICR mass spectrometry, directed to readers with no prior experience with the technique. We are able to explain the fundamental FT-ICR phenomena from a simplified theoretical treatment of ion behavior in idealized magnetic and electric fields. The effects of trapping voltage, trap size and shape, and other nonidealities are manifested mainly as perturbations that preserve the idealized ion behavior modified by appropriate numerical correction factors. Topics include: effect of ion mass, charge, magnetic field, and trapping voltage on ion cyclotron frequency; excitation and detection of ICR signals; mass calibration; mass resolving power and mass accuracy; upper mass limit(s); dynamic range; detection limit, strategies for mass and energy selection for MSn; ion axialization, cooling, and remeasurement; and means for guiding externally formed ions into the ion trap. The relation of FT-ICR MS to other types of Fourier transform spectroscopy and to the Paul (quadrupole) ion trap is described. The article concludes with selected applications, an appendix listing accurate fundamental constants needed for ultrahigh-precision analysis, and an annotated list of selected reviews and primary source publications that describe in further detail various FT-ICR MS techniques and applications.
Baryonic Resonances Mass Spectrum from a Modified Perturbative QCD
Cabo-Montes de Oca, Alejandro; Oca, Alejandro Cabo Montes de; Madrazo, Marcos Rigol
2001-01-01
A recently proposed modified perturbation expansion for QCD incorporating gluon condensation effects is employed to evaluate the quark self-energy in the simplest approximation. One of the solutions of the modified mass shell predicts mass values which increases monotonically with the corresponding Lagrangian mass for each kind of flavour. The mass spectrum of the ground states within the various groups of hadronic resonances and a class of mesonic ones is well predicted by the simple addition of the calculated constituent quark masses. These results suggest the gluon condensate nature of many baryonic resonances and the possibility of their description by a modified perturbative theory. Finally, it is conjectured that this procedure, after also introducing quark condensates in a same token as the gluonic ones, could predict the Lagrangian quark masses as well as the non-colored fermion (leptons and neutrinos) mass spectrum, through higher order radiative correction. Such a picture, if verified, would furnish...
Processing Chip for Thin Film Bulk Acoustic Resonator Mass Sensor
Directory of Open Access Journals (Sweden)
Pengcheng Jin
2012-01-01
Full Text Available Aimed at portable application, a new integrated process chip for thin film bulk acoustic resonator (FBAR mass sensor is proposed and verified with 0.18 um CMOS processing in this paper. The longitudinal mode FBAR with back-etched structure is fabricated, which has resonant frequency 1.878 GHz and factor 1200. The FBAR oscillator, based on the current-reuse structure, is designed with Modified Butterworth Van Dyke (MBVD model. The result shows that the FBAR oscillator operates at 1.878 GHz with a phase noise of −107 dBc/Hz and −135 dBc/Hz at 10 KHz and 100 KHz frequency offset, respectively. The whole process chip size with pads is 1300 μm × 950 μm. The FBAR and process chip are bonded together to sense tiny mass. The measurement results show that this chip precision is 1 KHz with the FBAR frequency gap from 25 kHz to 25 MHz.
A review of process advancement of novel metal spinning
Xia, Q.; Xiao, G; Van Long, H.; Cheng, X; X. Sheng
2014-01-01
Metal spinning technology has seen a rapid development in recent years. Novel spinning processes, such as non-axisymmetrical spinning, non-circular cross-section spinning and tooth-shaped spinning, are being developed. This has challenged the limitation of traditional spinning technology being used for manufacturing axisymmetrical, circular cross-section, and uniform wall-thickness parts. In this paper, the classification of the traditional spinning processes is proposed based on the material...
Spin pumping with coherent elastic waves
Weiler, M.; Huebl, H.; Goerg, F. S.; Czeschka, F. D.; Gross, R.; Goennenwein, S. T. B.
2012-02-01
The generation and detection of pure spin currents is an important topic for spintronic applications. Spin currents may be generated, e.g., via spin pumping. In this approach, a precessing magnetization relaxes via the emission of a spin current. Conventionally, electromagnetic waves, i.e. microwave photons, are used to drive the magnetization precession. We here show that a spin current can also be pumped by means of an acoustic wave, i.e. microwave phonons. In the experiments, coherent surface acoustic wave (SAW) phonons with a frequency of 1.55 GHz traverse a ferromagnetic thin film/normal metal (Co/Pt) bilayer. The SAW phonons drive the resonant magnetization precession via magnetoelastic coupling [1]. We use the inverse spin Hall voltage in the Pt film as a measure for the generated spin current and record its evolution as a function of time and external magnetic field magnitude and orientation. Our experiments show that a spin current is generated in the exclusive presence of a resonant elastic excitation. This establishes acoustic spin pumping as a resonant analogue to the spin Seebeck effect and opens intriguing perspectives for applications in, e.g., micromechanical resonators. [4pt] [1] M. Weiler et al., Phys. Rev. Lett. 106, 117601 (2011)
Giant magnetoresistance in organic spin-valves.
Xiong, Z H; Wu, Di; Vardeny, Z Valy; Shi, Jing
2004-02-26
A spin valve is a layered structure of magnetic and non-magnetic (spacer) materials whose electrical resistance depends on the spin state of electrons passing through the device and so can be controlled by an external magnetic field. The discoveries of giant magnetoresistance and tunnelling magnetoresistance in metallic spin valves have revolutionized applications such as magnetic recording and memory, and launched the new field of spin electronics--'spintronics'. Intense research efforts are now devoted to extending these spin-dependent effects to semiconductor materials. But while there have been noteworthy advances in spin injection and detection using inorganic semiconductors, spin-valve devices with semiconducting spacers have not yet been demonstrated. pi-conjugated organic semiconductors may offer a promising alternative approach to semiconductor spintronics, by virtue of their relatively strong electron-phonon coupling and large spin coherence. Here we report the injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.
Moderate positive spin Hall angle in uranium
Energy Technology Data Exchange (ETDEWEB)
Singh, Simranjeet; Anguera, Marta; Barco, Enrique del, E-mail: delbarco@ucf.edu, E-mail: cwmsch@rit.edu [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Springell, Ross [H. H. Will Laboratory, University of Bristol, Bristol BS2 8BS (United Kingdom); Miller, Casey W., E-mail: delbarco@ucf.edu, E-mail: cwmsch@rit.edu [School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, New York 14623 (United States)
2015-12-07
We report measurements of spin pumping and the inverse spin Hall effect in Ni{sub 80}Fe{sub 20}/uranium bilayers designed to study the efficiency of spin-charge interconversion in a super-heavy element. We employ broad-band ferromagnetic resonance on extended films to inject a spin current from the Ni{sub 80}Fe{sub 20} (permalloy) into the uranium layer, which is then converted into an electric field by the inverse spin Hall effect. Surprisingly, our results suggest a spin mixing conductance of order 2 × 10{sup 19} m{sup −2} and a positive spin Hall angle of 0.004, which are both merely comparable with those of several transition metals. These results thus support the idea that the electronic configuration may be at least as important as the atomic number in governing spin pumping across interfaces and subsequent spin Hall effects. In fact, given that both the magnitude and the sign are unexpected based on trends in d-electron systems, materials with unfilled f-electron orbitals may hold additional exploration avenues for spin physics.
Spin Interference in Rashba 2DEG Systems
Nitta, Junsaku
The gate controllable SOI provides useful information about spin interference.1 Spin interference effects are studied in two different interference loop structures. It is known that sample specific conductance fluctuations affect the conductance in the interference loop. By using array of many interference loops, we carefully pick up TRS Altshuler-Aronov-Spivak (AAS)-type oscillation which is not sample specific and depends on the spin phase. The experimentally obtained gate voltage dependence of AAS oscillations indicates that the spin precession angle can be controlled by the gate voltage.2 We demonstrate the time reversal Aharonov-Casher (AC) effect in small arrays of mesoscopic rings.3 By using an electrostatic gate we can control the spin precession angle rate and follow the AC phase over several interference periods. We also see the second harmonic of the AC interference, oscillating with half the period. The spin interference is still visible after more than 20π precession angle. We have proposed a Stern-Gerlach type spin filter based on the Rashba SOI.4 A spatial gradient of effective magnetic field due to the nonuniform SOI separates spin up and down electrons. This spin filter works even without any external magnetic fields and ferromagnetic contacts. We show the semiconductor/ferromagnet hybrid structure is an effective way to detect magnetization process of submicron magnets. The problem of the spin injection from ferromagnetic contact into 2DEG is also disicussed. Note from Publisher: This article contains the abstract only.
Paramagnetic and Antiferromagnetic Spin Seebeck Effect
Wu, Stephen
We report on the observation of the longitudinal spin Seebeck effect in both antiferromagnetic and paramagnetic insulators. By using a microscale on-chip local heater, it is possible to generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. This technique allows us to easily access low temperatures (200 mK) and high magnetic fields (14 T) through conventional dilution refrigeration and superconducting magnet setups. By exploring this regime, we detect the spin Seebeck effect through the spin-flop transition in antiferromagnetic MnF2 when a large magnetic field (>9 T) is applied along the easy axis direction. Using the same technique, we are also able to resolve a spin Seebeck effect from the paramagnetic phase of geometrically frustrated antiferromagnet Gd3Ga5O12 (gadolinium gallium garnet) and antiferromagnetic DyScO3 (DSO). Since these measurements occur above the ordering temperatures of these two materials, short-range magnetic order is implicated as the cause of the spin Seebeck effect in these systems. The discovery of the spin Seebeck effect in these two materials classes suggest that both antiferromagnetic spin waves and spin excitations from short range magnetic order may be used to generate spin current from insulators and that the spin wave spectra of individual materials are highly important to the specifics of the longitudinal spin Seebeck effect. Since insulating antiferromagnets and paramagnets are far more common than the typical insulating ferrimagnetic materials used in spin Seebeck experiments, this discovery opens up a large new class of materials for use in spin caloritronic devices. All authors acknowledge support of the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. The use of facilities at the Center for Nanoscale Materials, was supported by the U.S. DOE, BES under Contract No. DE-AC02-06CH11357.
Noguchi, Ryo; Kuroda, Kenta; Yaji, K.; Kobayashi, K.; Sakano, M.; Harasawa, A.; Kondo, Takeshi; Komori, F.; Shin, S.
2017-01-01
We use spin- and angle-resolved photoemission spectroscopy (SARPES) combined with a polarization-variable laser and investigate the spin-orbit coupling effect under interband hybridization of Rashba spin-split states for the surface alloys Bi/Ag(111) and Bi/Cu(111). In addition to the conventional band mapping of photoemission for Rashba spin splitting, the different orbital and spin parts of the surface wave function are directly imaged into energy-momentum space. It is unambiguously revealed that the interband spin-orbit coupling modifies the spin and orbital character of the Rashba surface states leading to the enriched spin-orbital entanglement and the pronounced momentum dependence of the spin polarization. The hybridization thus strongly deviates the spin and orbital characters from the standard Rashba model. The complex spin texture under interband spin-orbit hybridization proposed by first-principles calculation is experimentally unraveled by SARPES with a combination of p - and s -polarized light.
Spin transfer torques and spin dynamics in point contacts and spin-flop tunnel junctions
Konovalenko, Alexander
2008-01-01
The first part of this thesis is an experimental study of the spin-dependent transport in magnetic point contacts. Nano-contacts are produced micromechanically, by bringing a sharpened non-magnetic (N) tip into contact with a ferromagnetic (F) film. The magnetic and magneto-transport properties of such N/F nanocontacts are studied using transport spectroscopy, spanning the ballistic, diffusive, and thermal transport regimes. Single N/F interfaces can exhibit current driven magnetic excitation...
Spin pumping and spin-orbit effects in Ge (Conference Presentation)
Oyarzún, Simón; Nandy, Ashis Kumar; Rortais, Fabien; Rojas-Sánchez, Juan Carlos; Laczkowski, Piotr; Pouget, Stephanie; Okuno, Hanako; Vila, Laurent; Vergnaud, Céline; Beigne, Cyrille; Marty, Alain; Attané, Jean Philippe; Gambarelli, Serge; George, Jean Marie; Jaffres, Henri; Blügel, Stefan; Jamet, Matthieu
2016-10-01
The field of spintronics is based on the manipulation of the spin degree of freedom. It uses the carrier spin angular momentum as a basic functional unit in addition to the charge. The first requirement of a semiconductor-based spintronic technology is the efficient generation of spin-polarized carriers into the device heterostructure made of Si or Ge (the materials of mainstream microelectronics) at room temperature. In this presentation, we focus on the generation of a sizeable spin population into Ge by spin pumping. Spin pumping corresponds to the generation of a pure spin current in the Ge film by exciting the ferromagnetic resonance of an adjacent ferromagnetic electrode with microwaves. The pure spin current is then detected using spin-orbit based effects. Our aim is to understand the basic mechanisms of spin pumping into Ge as well as the spin-to-charge conversion by inverse spin Hall effect (ISHE, bulk effect) [1-4] and Rashba-Edelstein effect (interface effect) [5]. The influence of interface states is clearly demonstrated. Moreover, using the spin-split Rashba sub-surface states of the Ge(111) surface, we succeeded in demonstrating a giant conversion of a spin current generated by spin pumping into a charge current by the Rashba-Edelstein effect [6,7]. Our experimental findings are supported by ab-initio calculations. 1. Rojas-Sánchez, J.-C. et al. Spin pumping and inverse spin Hall effect in germanium. Phys. Rev. B 88, (2013). 2. Kato, Y. K., Myers, R. C., Gossard, A. C. and Awschalom, D. D. Observation of the spin Hall effect in semiconductors. Science 306, 1910-1913 (2004). 3. Valenzuela, S. O. and Tinkham, M. Direct electronic measurement of the spin Hall effect. Nature 442, 176-179 (2006). 4. Saitoh, E., Ueda, M., Miyajima, H. and Tatara, G. Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect. Appl Phys Lett 88, 2509 (2006). 5. Bychkov, Y. A. and Rashba, E. I. Oscillatory effects and the magnetic
Shen, SQ; Ma, X.; Hu, L.; R. Tao
2004-01-01
In a two-dimensional electron gas with Rashba spin-orbit coupling, the external electric field may cause a spin Hall current in the direction perpendicular to the electric field. This effect was called the intrinsic spin Hall effect. In this paper, we investigate the influences of spin accumulation on this intrinsic spin Hall effect. We show that due to the existence of boundaries in a real sample, the spin Hall current generated by the intrinsic spin Hall effect will cause spin accumulation ...
Cavity cooling of an ensemble spin system.
Wood, Christopher J; Borneman, Troy W; Cory, David G
2014-02-07
We describe how sideband cooling techniques may be applied to large spin ensembles in magnetic resonance. Using the Tavis-Cummings model in the presence of a Rabi drive, we solve a Markovian master equation describing the joint spin-cavity dynamics to derive cooling rates as a function of ensemble size. Our calculations indicate that the coupled angular momentum subspaces of a spin ensemble containing roughly 10(11) electron spins may be polarized in a time many orders of magnitude shorter than the typical thermal relaxation time. The described techniques should permit efficient removal of entropy for spin-based quantum information processors and fast polarization of spin samples. The proposed application of a standard technique in quantum optics to magnetic resonance also serves to reinforce the connection between the two fields, which has recently begun to be explored in further detail due to the development of hybrid designs for manufacturing noise-resilient quantum devices.
Anisotropic Spin Splitting in Step Quantum Wells
Institute of Scientific and Technical Information of China (English)
HAO Ya-Fei; CHEN Yong-Hai; HAO Guo-Dong; WANG Zhan-Guo
2009-01-01
By the method of finite difference,the anisotropic spin splitting of the Alx Ga1-x As/GaAs/Aly Ga1-y As/Alx Ga1-x As step quantum wells (QWs) are theoretically investigated considering the interplay of the bulk inversion asymmetry and structure inversion asymmetry induced by step quantum well structure and external electric field.We demonstrate that the anisotropy of the total spin splitting can be controlled by the shape of the QWs and the external electric field.The interface related Rashba effect plays an important effect on the anisotropic spin splitting by influencing the magnitude of the spin splitting and the direction of electron spin.The Rashba spin splitting presents in the step quantum wells due to the interface related Rashba effect even without external electric field or magnetic field.
Spin dynamics in driven composite multiferroics
Energy Technology Data Exchange (ETDEWEB)
Wang, Zidong, E-mail: Zidong.Wang@auckland.ac.nz; Grimson, Malcolm J. [Department of Physics, The University of Auckland, Auckland 1010 (New Zealand)
2015-09-28
A spin dynamics approach has been used to study the behavior of the magnetic spins and the electric pseudo-spins in a 1-D composite multiferroic chain with a linear magneto-electric coupling at the interface. The response is investigated with either external magnetic or electric fields driving the system. The spin dynamics is based on the Landau-Lifshitz-Gilbert equation. A Gaussian white noise is later added into the dynamic process to include the thermal effects. The interface requires a closer inspection of the magneto-electric effects. Thus, we construct a 2-D ladder model to describe the behavior of the magnetic spins and the electric pseudo-spins with different magneto-electric couplings.
Photonic spin Hall effect in topological insulators
Zhou, Xinxing; Ling, Xiaohui; Chen, Shizhen; Luo, Hailu; Wen, Shuangchun
2013-01-01
In this paper we theoretically investigate the photonic spin Hall effect (SHE) of a Gaussian beam reflected from the interface between air and topological insulators (TIs). The photonic SHE is attributed to spin-orbit coupling and manifests itself as in-plane and transverse spin-dependent splitting. We reveal that the spin-orbit coupling effect in TIs can be routed by adjusting the axion angle variations. Unlike the transverse spin-dependent splitting, we find that the in-plane one is sensitive to the axion angle. It is shown that the polarization structure in magneto-optical Kerr effect is significantly altered due to the spin-dependent splitting in photonic SHE. We theoretically propose a weak measurement method to determine the strength of axion coupling by probing the in-plane splitting of photonic SHE.
Magnetizing and heating quantum spin ladders
Indian Academy of Sciences (India)
Andrey Zheludev
2008-11-01
Quasi-one-dimensional quantum spin liquids, such as weakly coupled even-legged S=1/2 spin ladders or spin tubes, have a singlet non-magnetic ground state and gap in the excitation spectrum. Their low-temperature properties can be described in terms of triplet massive quasiparticles. These magnons possess some unique features due to the peculiar topology of one dimension. For example, two-particle interactions totally destroy single-particle states for certain energy and momentum transfers, resulting in the so-called termination of the magnon spectrum. At high field a Bose–Einstein condensation of these magnons produces a `quantum spin solid' phase, where `conventional` antiferromagnetic order coexists with excitations that are totally outside conventional spin wave theory. At finite temperatures strong repulsion between quasiparticles leads to a universal renormalization of their masses and lifetimes. These diverse phenomena are best probed by neutron scattering experiments that directly measure the spin correlation functions and excitation spectra.
Transformation of spin current by antiferromagnetic insulators
Khymyn, Roman; Lisenkov, Ivan; Tiberkevich, Vasil S.; Slavin, Andrei N.; Ivanov, Boris A.
2016-06-01
It is demonstrated theoretically that a thin layer of an anisotropic antiferromagnetic (AFM) insulator can effectively conduct spin current through the excitation of a pair of evanescent AFM spin wave modes. The spin current flowing through the AFM is not conserved due to the interaction between the excited AFM modes and the AFM lattice and, depending on the excitation conditions, can be either attenuated or enhanced. When the phase difference between the excited evanescent modes is close to π /2 , there is an optimum AFM thickness for which the output spin current reaches a maximum, which can significantly exceed the magnitude of the input spin current. The spin current transfer through the AFM depends on the ambient temperature and increases substantially when temperature approaches the Néel temperature of the AFM layer.
Theory of electron spin echoes in solids
Asadullina, N Y; Asadullin, Y Y
2002-01-01
We propose modified Bloch equations (MBEs) with specific power-dependent relaxation and dispersion parameters characteristic for two-pulse excitation and when the magnetic dipole-dipole interactions in the electron spin system control the dephasing. We discriminate between the 'active' (excited by both pulses) and 'passive' (excited by the second pulse only) spins: it is shown that the 'active' spins participate in a new effect, an active spin frequency modulation effect giving rise to the power-dependent dispersion and multiple electron spin echoes (ESEs); the 'passive' spins contribute to the power-dependent relaxation. The MBEs are solved and a general expression for the two-pulse ESEs is obtained. Detailed numerical analysis of this expression gives results in good quantitative agreement with the recent experiments on the two-pulse ESEs at conventional low applied fields. The developed theory is applied also to high field ESEs, which are promising for future investigations. On the basis of published resul...
Exploring frustrated magnetism with artificial spin ice
Gilbert, Ian; Ilic, B. Robert
2016-10-01
Nanomagnet arrays known as artificial spin ice provide insight into the microscopic details of frustrated magnetism because, unlike natural frustrated magnets, the individual moments can be experimentally resolved and the lattice geometry can be easily tuned. Most studies of artificial spin ice focus on two lattice geometries, the square and the kagome lattices, due to their direct correspondence to natural spin ice materials such as Dy2Ti2O7. In this work, we review experiments on these more unusual lattice geometries and introduce a new type of nanomagnet array, artificial spin glass. Artificial spin glass is a two-dimensional array of nanomagnets with random locations and orientations and is designed to elucidate the more complex frustration found in spin glass materials.
Tidal deformations of a spinning compact object
Pani, Paolo; Maselli, Andrea; Ferrari, Valeria
2015-01-01
The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...
Theory of Spin Loss at Metallic Interfaces
Belashchenko, K. D.; Kovalev, Alexey A.; van Schilfgaarde, M.
2016-11-01
Interfacial spin-flip scattering plays an important role in magnetoelectronic devices. Spin loss at metallic interfaces is usually quantified by matching the magnetoresistance data for multilayers to the Valet-Fert model, while treating each interface as a fictitious bulk layer whose thickness is δ times the spin-diffusion length. By employing the properly generalized circuit theory and the scattering matrix approaches, we derive the relation of the parameter δ to the spin-flip transmission and reflection probabilities at an individual interface. It is found that δ is proportional to the square root of the probability of spin-flip scattering. We calculate the spin-flip scattering probabilities for flat and rough Cu /Pd interfaces using the Landauer-Büttiker method based on the first-principles electronic structure and find δ to be in reasonable agreement with experiment.
Cross relaxation in nitroxide spin labels
Marsh, Derek
2016-11-01
Cross relaxation, and mI -dependence of the intrinsic electron spin-lattice relaxation rate We , are incorporated explicitly into the rate equations for the electron-spin population differences that govern the saturation behaviour of 14N- and 15N-nitroxide spin labels. Both prove important in spin-label EPR and ELDOR, particularly for saturation recovery studies. Neither for saturation recovery, nor for CW-saturation EPR and CW-ELDOR, can cross relaxation be described simply by increasing the value of We , the intrinsic spin-lattice relaxation rate. Independence of the saturation recovery rates from the hyperfine line pumped or observed follows directly from solution of the rate equations including cross relaxation, even when the intrinsic spin-lattice relaxation rate We is mI -dependent.
Spin-Valley Beam Splitter in Graphene
Song, Yu; Shi, Zhi-Gui; Li, Shun; Zhang, Jian
2016-01-01
The fourfold spin-valley degenerate degrees of freedom in bulk graphene can support rich physics and novel applications associated with multicomponent quantum Hall effects and linear conductance filtering. In this work, we study how to break the spin-valley degeneracy of electron beams spatially. We propose a spin-valley beam splitter in a gated ferromagnetic/pristine/strained graphene structure. We demonstrate that, in a full resonant tunneling regime for all spin-valley beam components, the formation of quasi-standing waves can lead four giant lateral Goos-H\\"{a}nchen shifts as large as the transverse beam width, while the interplay of the two modulated regions can lead difference of resonant angles or energies for the four spin-valley flavors, manifesting an effective spin-valley beam splitting effect. The beam splitting effect is found to be controllable by the gating and strain.
Directional spin wavelets on the sphere
McEwen, Jason D; Büttner, Martin; Peiris, Hiranya V; Wiaux, Yves
2015-01-01
We construct a directional spin wavelet framework on the sphere by generalising the scalar scale-discretised wavelet transform to signals of arbitrary spin. The resulting framework is the only wavelet framework defined natively on the sphere that is able to probe the directional intensity of spin signals. Furthermore, directional spin scale-discretised wavelets support the exact synthesis of a signal on the sphere from its wavelet coefficients and satisfy excellent localisation and uncorrelation properties. Consequently, directional spin scale-discretised wavelets are likely to be of use in a wide range of applications and in particular for the analysis of the polarisation of the cosmic microwave background (CMB). We develop new algorithms to compute (scalar and spin) forward and inverse wavelet transforms exactly and efficiently for very large data-sets containing tens of millions of samples on the sphere. By leveraging a novel sampling theorem on the rotation group developed in a companion article, only hal...
Spin Dynamics in Confined Magnetic Structures III
Hillebrands, Burkard
2006-01-01
This third volume of Spin Dynamics in Confined Magnetic Structures addresses central aspects of spin-dynamic phenomena, including recent new developments, on a tutorial level. Researchers will find a comprehensive compilation of the current work in the field. Introductory chapters help newcomers to understand the basic concepts. The more advanced chapters give the current state of the art of spin dynamic issues ranging from the femtosecond to the microsecond regime. This volume concentrates on new experimental techniques such as ferromagnetic-resonance-force microscopy and two-photon photoemission, as well as on aspects of precessional switching, spin-wave excitation, vortex dynamics, spin relaxation, domain-wall dynamics in nanowires and their applications to magnetic logic devices. An important chapter is devoted to the presently very hot subject of the spin-transfer torque, combining the physics of electronic transport and micromagnetics. The comprehensive presentation of these developments makes this volu...
Spin control of light with hyperbolic metasurfaces
Yermakov, Oleh Y; Bogdanov, Andrey A; Iorsh, Ivan V; Bliokh, Konstantin Y; Kivshar, Yuri S
2016-01-01
Transverse spin angular momentum is an inherent feature of evanescent waves which may have applications in nanoscale optomechanics, spintronics, and quantum information technology due to the robust spin-directional coupling. Here we analyze a local spin angular momentum density of hybrid surface waves propagating along anisotropic hyperbolic metasurfaces. We reveal that, in contrast to bulk plane waves and conventional surface plasmons at isotropic interfaces, the spin of the hybrid surface waves can be engineered to have an arbitrary angle with the propagation direction. This property allows to tailor directivity of surface waves via the magnetic control of the spin projection of quantum emitters, and it can be useful for optically controlled spin transfer.
Nuclear spin polarized H and D by means of spin-exchange optical pumping
Stenger, Jörn; Grosshauser, Carsten; Kilian, Wolfgang; Nagengast, Wolfgang; Ranzenberger, Bernd; Rith, Klaus; Schmidt, Frank
1998-01-01
Optically pumped spin-exchange sources for polarized hydrogen and deuterium atoms have been demonstrated to yield high atomic flow and high electron spin polarization. For maximum nuclear polarization the source has to be operated in spin temperature equilibrium, which has already been demonstrated for hydrogen. In spin temperature equilibrium the nuclear spin polarization PI equals the electron spin polarization PS for hydrogen and is even larger than PS for deuterium. We discuss the general properties of spin temperature equilibrium for a sample of deuterium atoms. One result are the equations PI=4PS/(3+PS2) and Pzz=PSṡPI, where Pzz is the nuclear tensor polarization. Furthermore we demonstrate that the deuterium atoms from our source are in spin temperature equilibrium within the experimental accuracy.
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.
Energy Technology Data Exchange (ETDEWEB)
Tatara, Gen, E-mail: gen.tatara@riken.jp [RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198 Japan (Japan); Nakabayashi, Noriyuki [RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198 Japan (Japan); Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 Japan (Japan)
2014-05-07
Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.
Distinct spin liquids and their transitions in spin-1/2 XXZ kagome antiferromagnets.
He, Yin-Chen; Chen, Yan
2015-01-23
By using the density matrix renormalization group approach, we study spin-liquid phases of spin-1/2 XXZ kagome antiferromagnets. We find that the emergence of the spin-liquid phase is independent of the anisotropy of the XXZ interaction. In particular, the two extreme limits-the Ising (a strong S^{z} interaction) and the XY (zero S^{z} interaction)-host the same spin-liquid phases as the isotropic Heisenberg model. Both a time-reversal-invariant spin liquid and a chiral spin liquid with spontaneous time-reversal symmetry breaking are obtained. We show that they evolve continuously into each other by tuning the second- and the third-neighbor interactions. And last, we discuss possible implications of our results for the nature of spin liquid in nearest-neighbor XXZ kagome antiferromagnets, including the nearest-neighbor spin-1/2 kagome antiferromagnetic Heisenberg model.
Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure
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.
Strong spin-orbit fields and Dyakonov-Perel spin dephasing in supported metallic films
Long, Nguyen H.; Mavropoulos, Phivos; Bauer, David S. G.; Zimmermann, Bernd; Mokrousov, Yuriy; Blügel, Stefan
2016-11-01
Spin dephasing by the Dyakonov-Perel mechanism in metallic films deposited on insulating substrates is revealed, and quantitatively examined by means of density functional calculations combined with a kinetic equation. The surface-to-substrate asymmetry, probed by the metal wave functions in thin films, is found to produce strong spin-orbit fields and a fast Larmor precession, giving a dominant contribution to spin decay over the Elliott-Yafet spin relaxation up to a thickness of 70 nm. The spin dephasing is oscillatory in time with a rapid (subpicosecond) initial decay. However, parts of the Fermi surface act as spin traps, causing a persistent tail signal lasting 1000 times longer than the initial decay time. It is also found that the decay depends on the direction of the initial spin polarization, resulting in a spin-dephasing anisotropy of 200% in the examined cases.
Frecus, Bogdan; Rinkevicius, Zilvinas; Murugan, N Arul; Vahtras, Olav; Kongsted, Jacob; Ågren, Hans
2013-02-21
Encapsulation of spin-labels into "host" compounds, like cucurbit[n]urils or cyclodextrins, in solutions has profound effects on the EPR spin Hamiltonian parameters of the spin-labels. In this work we study the microscopic origin of the EPR spin Hamiltonian parameters of spin-labels enclosed in hydrophobic cavities. We focus on the dependence of the EPR properties of encapsulated spin-labels on the hydrogen bonding topologies that occur upon encapsulation, and quantize various contributions to these parameters according to specific hydrogen bonding patterns. The obtained results provide refined insight into the role of the hydrogen bonding induced encapsulation shifts of EPR spin Hamiltonian parameters in solvated "spin-label@host compound" complexes.
A Calculus for Higher Spin Interactions
Joung, Euihun; Waldron, Andrew
2013-01-01
Higher spin theories can be efficiently described in terms of auxiliary St\\"uckelberg or projective space field multiplets. By considering how higher spin models couple to scale, these approaches can be unified in a conformal geometry/tractor calculus framework. We review these methods and apply them to higher spin vertices to obtain a generating function for massless, massive and partially massless three-point interactions.
Spin Forming of Aluminum Metal Matrix Composites
Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)
2001-01-01
An exploratory effort between NASA-Marshall Space Flight Center (MSFC) and SpinCraft, Inc., to experimentally spin form cylinders and concentric parts from small and thin sheets of aluminum Metal Matrix Composites (MMC), successfully yielded good microstructure data and forming parameters. MSFC and SpinCraft will collaborate on the recent technical findings and develop strategy to implement this technology for NASA's advanced propulsion and airframe applications such as pressure bulkheads, combustion liner assemblies, propellant tank domes, and nose cone assemblies.
Melix, Patrick; Rüger, Robert; Heine, Thomas
2016-01-01
We evaluate the performance of spin-polarized DFTB within the SCC-DFTB (also known as DFTB2) model. The method has been implemented in the ADF modeling suite. We briefly review how spin polarization is incorporated into the DFTB2 method and validate the method in terms of structural parameters and energy using the GMTKN30 test set, from which we used 288 spin-polarized systems.
Thermal imaging of spin Peltier effect
Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-ichi
2016-01-01
When a charge current is applied to a junction comprising two different conductors, its temperature increases or decreases depending on the direction of the charge current. This phenomenon is called the Peltier effect, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The "spin Peltier effect" modulates the temperature of a magnetic junction depending on the direction of a spin c...
Geometric Photonic Spin Hall Effect with Metapolarization
2014-01-01
We develop a geometric photonic spin Hall effect (PSHE) which manifests as spin-dependent shift in momentum space. It originates from an effective space-variant Pancharatnam-Berry (PB) phase created by artificially engineering the polarization distribution of the incident light. Unlikely the previously reported PSHE involving the light-matter interaction, the resulting spin-dependent splitting in the geometric PSHE is purely geometrically depend upon the polarization distribution of light whi...
Correlated spin networks in frustrated systems
Stone, Thomas E.; McKay, Susan R.
2010-08-01
We introduce a network model for frustrated spin systems based on highly correlated spin fluctuations, to quantify and visualize their ordering. This model shows that networks of strongly correlated but non-contiguous spins exist at low temperatures on a triangular Ising lattice with competing nearest-neighbor interactions. This finding is consistent with chaotic renormalization-group trajectories previously reported for frustrated hierarchical lattices.
The nucleon spin structure at short distance
Seidl, Ralf
2008-10-01
The spin structure of the nucleon has been the basis of several surprises in the past. After the EMC experiment showed that the quark spin contribution to the nucleon spin was small, several experiments were performed to further investigate this ``spin crisis.'' Deep inelastic scattering (DIS) experiments at CERN, SLAC, and DESY successfully confirmed the low quark spin contribution to the nucleon. Using semi-inclusive DIS, SMC, HERMES and COMPASS were also able to obtain flavor separated quark polarizations. DIS experiments are only sensitive to gluon polarization at NLO via the QCD evolution of the structure function g1, or through di-jet/hadron production in photon-gluon fusion processes. Proton-proton collisions are sensitive to the gluon polarization at leading order. The RHIC experiments PHENIX and STAR have measured inclusive pion and jet asymmetries which exclude huge gluon polarizations but a substantial contribution to the spin of the nucleon is still possible. Another aspect of spin measurements are transverse spin phenomena. Once deemed to be vanishing in perturbative QCD recent nonzero transverse single spin asymmetries observed at RHIC and HERMES could be explained in the framework of transverse momentum dependent (TMD) distribution and fragmentation functions. One is the so-called Sivers function which requires a nonzero parton orbital angular momentum. Early global analysises were able to combine the data obtained at RHIC, COMPASS and HERMES. Another TMD function is the Collins fragmentation function, first measured at BELLE, which serves as a transverse spin analyzer to extract the quark transverse spin distribution from the SIDIS experiments. Also here a first global analysis of SIDIS and BELLE data has been successfully performed. An overview on recent spin related measurements at short distance, performed at PHENIX, STAR, BRAHMS, HERMES, COMPASS and Belle will be given.
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The previous works for high spins states of 86Sr were very scarce. In the past, the spin of highest level of 86Sr was 13 found by the reaction 84Kr(α, 2nγ)86Sr in 28 MeV. The current work updates the level scheme of 86Sr to get more information about high spin states in 86Sr.
Spin state switching in iron coordination compounds
Directory of Open Access Journals (Sweden)
Philipp Gütlich
2013-02-01
Full Text Available The article deals with coordination compounds of iron(II that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors as well as optical devices.The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the chemical nature that is important for the occurrence of spin crossover will be made. A subsequent section describes the molecular consequences of spin crossover and the variety of physical techniques usually applied for their characterization. The effects of light irradiation (LIESST and application of pressure are subjects of two separate sections. The major part of this account concentrates on selected spin crossover compounds of iron(II, with particular emphasis on the chemical and physical influences on the spin crossover behavior. The vast variety of compounds exhibiting this fascinating switching phenomenon encompasses mono-, oligo- and polynuclear iron(II complexes and cages, polymeric 1D, 2D and 3D systems, nanomaterials, and polyfunctional materials that combine spin crossover with another physical or chemical property.
Spin-Seebeck effect in a strongly interacting Fermi gas
Wong, C.H.; Stoof, H.T.C.; Duine, R.A.
2012-01-01
We study the spin-Seebeck effect in a strongly interacting, two-component Fermi gas and propose an experiment to measure this effect by relatively displacing spin-up and spin-down atomic clouds in a trap using spin-dependent temperature gradients. We compute the spin-Seebeck coefficient and related
Experimental Test of the Spin Mixing Interface Conductivity Concept
Weiler, M.; Althammer, M.; Schreier, M.; Lotze, J.; Pernpeintner, M.; Meyer, S.; Huebl, H.; Gross, R.; Kamra, A.; Xiao, J.; Chen, Y.T.; Jiao, H.J.; Bauer, G.E.W.; Goennenwein, S.T.B.
2013-01-01
We perform a quantitative, comparative study of the spin pumping, spin Seebeck, and spin Hall magnetoresistance effects, all detected via the inverse spin Hall effect in a series of over 20 yttrium iron garnet/Pt samples. Our experimental results fully support present, exclusively spin current-ba
Introduction of Spin-Orbit Interaction into Graphene with Hydrogenation
Nakamura, Taketomo; Haruyama, Junji; Katsumoto, Shingo
2016-10-01
The introduction of the spin-orbit interaction (SOI) into graphene with weak hydrogenation (˜0.1%) by the dissociation of hydrogen silsesquioxane resist has been confirmed through the appearance of the inverse spin Hall effect. The spin current was produced by spin injection from permalloy electrodes excluding a non-spin-related experimental artifact.
Spin transfer in antiferromagnets (Conference Presentation)
Moriyama, Takahiro
2016-10-01
Since antiferromagnets (AFMs) have no spontaneous magnetization unlike ferromagnetic materials, it is not easy to manipulate the magnetic moments in AFMs by external magnetic field. However, recent theoretical studies suggest that it is possible to manipulate the magnetization in AFMs by spin-transfer-torque in a similar manner to ferromagnetic materials. In this study, we perform spin-toque ferromagnetic resonance (ST-FMR) measurements on FeNi/NiO/Pt multilayers to experimentally investigate the interaction between the spin current and the magnetic moments of antiferromagnetic NiO. The spin current is injected to the NiO by the spin Hall effect in Pt. The monotonous change in the FMR linewidth of this system with respect to the spin current can be interpreted in a way that the spin current is transferred through the NiO and interacts with the FeNi. This intriguing spin current transport can be explained by the angular momentum transfer mediated by the antiferromagnetic magnons. The results assure that the spin current exerts a torque on the NiO magnetic moments and excites their dynamics. In the talk, recent results will be also discussed.
Universal spin-momentum locked optical forces
Kalhor, Farid; Thundat, Thomas; Jacob, Zubin
2016-02-01
Evanescent electromagnetic waves possess spin-momentum locking, where the direction of propagation (momentum) is locked to the inherent polarization of the wave (transverse spin). We study the optical forces arising from this universal phenomenon and show that the fundamental origin of recently reported non-trivial optical chiral forces is spin-momentum locking. For evanescent waves, we show that the direction of energy flow, the direction of decay, and the direction of spin follow a right hand rule for three different cases of total internal reflection, surface plasmon polaritons, and HE11 mode of an optical fiber. Furthermore, we explain how the recently reported phenomena of lateral optical force on chiral and achiral particles are caused by the transverse spin of the evanescent field and the spin-momentum locking phenomenon. Finally, we propose an experiment to identify the unique lateral forces arising from the transverse spin in the optical fiber and point to fundamental differences of the spin density from the well-known orbital angular momentum of light. Our work presents a unified view on spin-momentum locking and how it affects optical forces on chiral and achiral particles.
Doppler effect induced spin relaxation boom
Zhao, Xinyu; Huang, Peihao; Hu, Xuedong
2016-03-01
We study an electron spin qubit confined in a moving quantum dot (QD), with our attention on both spin relaxation, and the product of spin relaxation, the emitted phonons. We find that Doppler effect leads to several interesting phenomena. In particular, spin relaxation rate peaks when the QD motion is in the transonic regime, which we term a spin relaxation boom in analogy to the classical sonic boom. This peak indicates that a moving spin qubit may have even lower relaxation rate than a static qubit, pointing at the possibility of coherence-preserving transport for a spin qubit. We also find that the emitted phonons become strongly directional and narrow in their frequency range as the qubit reaches the supersonic regime, similar to Cherenkov radiation. In other words, fast moving excited spin qubits can act as a source of non-classical phonons. Compared to classical Cherenkov radiation, we show that quantum dot confinement produces a small but important correction on the Cherenkov angle. Taking together, these results have important implications to both spin-based quantum information processing and coherent phonon dynamics in semiconductor nanostructures.
Spin-crossover materials properties and applications
Halcrow, Malcolm A
2013-01-01
The phenomenon of spin-crossover has a large impact on the physical properties of a solid material, including its colour, magnetic moment, and electrical resistance. Some materials also show a structural phase change during the transition. Several practical applications of spin-crossover materials have been demonstrated including display and memory devices, electrical and electroluminescent devices, and MRI contrast agents. Switchable liquid crystals, nanoparticles, and thin films of spin-crossover materials have also been achieved. Spin-Crossover Materials: Properties and Applicat
Handbook of spin transport and magnetism
Tsymbal, Evgeny Y
2011-01-01
In the past several decades, the research on spin transport and magnetism has led to remarkable scientific and technological breakthroughs, including Albert Fert and Peter Grünberg's Nobel Prize-winning discovery of giant magnetoresistance (GMR) in magnetic metallic multilayers. Handbook of Spin Transport and Magnetism provides a comprehensive, balanced account of the state of the art in the field known as spin electronics or spintronics. It reveals how key phenomena first discovered in one class of materials, such as spin injection in metals, have been revisited decades later in other materia
Observation of a Hybrid Spin Resonance
Bai, M.; Allgower, C.; Ahrens, L.; Alessi, J.; Brown, K.; Bunce, G.; Cameron, P.; Chu, C. M.; Courant, E. D.; Glenn, J. W.; Huang, H.; Jeon, D.; Kponou, A. E.; Krueger, K.; Luccio, A.; Makdisi, Y. I.; Lee, S. Y.; Ratner, L.; Reece, K.; Roser, T.; Spinka, H.; Syphers, M. J.; Tsoupas, N.; Underwood, D. G.; van Asselt, W.; Williams, N.; Yokosawa, A.
2000-02-01
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This ``hybrid'' spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors.
Long-range spin transport in superconductors
Energy Technology Data Exchange (ETDEWEB)
Beckmann, Detlef; Wolf, Michael J. [Institut fuer Nanotechnologie, Karlsruher Institut fuer Technologie (Germany); Huebler, Florian [Institut fuer Festkoerperphysik, Karlsruher Institut fuer Technologie (Germany); Loehneysen, Hilbert von [Institut fuer Festkoerperphysik, Karlsruher Institut fuer Technologie (Germany); Physikalisches Institut, Karlsruher Institut fuer Technologie (Germany)
2012-07-01
Recently, there has been some controversy about spin-polarized quasiparticle transport and relaxation in superconductors, with reports of both anomalously short or anomalously long relaxation times as compared to the normal state. Here, we report on non-local transport in multiterminal superconductor-ferromagnet structures. We find signatures of spin transport over distances much larger than the normal-state spin-diffusion length in the presence of a large Zeeman splitting of the quasiparticle states. The relaxation length shows a nearly linear increase with magnetic field, hinting at a freeze-out of spin relaxation by the Zeeman splitting.
Blockspin Cluster Algorithms for Quantum Spin Systems
Wiese, U J
1992-01-01
Cluster algorithms are developed for simulating quantum spin systems like the one- and two-dimensional Heisenberg ferro- and anti-ferromagnets. The corresponding two- and three-dimensional classical spin models with four-spin couplings are maped to blockspin models with two-blockspin interactions. Clusters of blockspins are updated collectively. The efficiency of the method is investigated in detail for one-dimensional spin chains. Then in most cases the new algorithms solve the problems of slowing down from which standard algorithms are suffering.
Observation of the spin Peltier effect
Flipse, J.; Dejene, F. K.; Wagenaar, D.; Bauer, G. E. W.; Youssef, J. Ben; van Wees, B. J.
2013-01-01
We report the observation of the spin Peltier effect (SPE) in the ferrimagnetic insulator Yttrium Iron Garnet (YIG), i.e. a heat current generated by a spin current flowing through a Platinum (Pt)|YIG interface. The effect can be explained by the spin torque that transforms the spin current in the Pt into a magnon current in the YIG. Via magnon-phonon interactions the magnetic fluctuations modulate the phonon temperature that is detected by a thermopile close to the interface. By finite-eleme...
Exact diagonalization of quantum-spin models
Lin, H. Q.
1990-10-01
We have developed a technique to replace hashing in implementing the Lanczös method for exact diagonalization of quantum-spin models that enables us to carry out numerical studies on substantially larger lattices than previously studied. We describe the algorithm in detail and present results for the ground-state energy, the first-excited-state energy, and the spin-spin correlations on various finite lattices for spins S=1/2, 1, 3/2, and 2. Results for an infinite system are obtained by extrapolation. We also discuss the generalization of our method to other models.
Synchronous Spin-Exchange Optical Pumping
Korver, Anna; Bulatowicz, Mike; Walker, Thad
2015-01-01
We describe a new approach to precision NMR with hyperpolarized gases designed to mitigate NMR frequency shifts due to the alkali spin exchange field. The electronic spin polarization of optically pumped alkali atoms is square-wave modulated at the noble-gas NMR frequency and oriented transverse to the DC Fourier component of the NMR bias field. Noble gas NMR is driven by spin-exchange collisions with the oscillating electron spins. On resonance, the time-average torque from the oscillating spin-exchange field produced by the alkali spins is zero. Implementing the NMR bias field as a sequence of alkali 2$ \\pi $-pulses enables synchronization of the alkali and noble gas spins despite a 1000-fold discrepancy in gyromagnetic ratio. We demonstrate this method with Rb and Xe, and observe novel NMR broadening effects due to the transverse oscillating spin exchange field. When uncompensated, the spin-exchange field at high density broadens the NMR linewidth by an order of magnitude, with an even more dramatic suppre...
21st International Symposium on Spin Physics
Ma, Bo-Qiang; SPIN 2014; SPIN2014
2016-01-01
This special volume collected important papers written by leading experts, highlighting the latest research findings in various topics of spin phenomena in particle and nuclear physics. The contents are originated from the plenary talks at the latest symposium of the Spin Physics series (SPIN2014) which was held in Beijing, China, October 20-24, 2014.The volume also comprises a special collection of contributions in memory of the late Professor Michel Borghini, an outstanding physicist well remembered for his great contributions to the progress of high energy spin physics.
Circuit quantum electrodynamics with a spin qubit.
Petersson, K D; McFaul, L W; Schroer, M D; Jung, M; Taylor, J M; Houck, A A; Petta, J R
2012-10-18
Electron spins trapped in quantum dots have been proposed as basic building blocks of a future quantum processor. Although fast, 180-picosecond, two-quantum-bit (two-qubit) operations can be realized using nearest-neighbour exchange coupling, a scalable, spin-based quantum computing architecture will almost certainly require long-range qubit interactions. Circuit quantum electrodynamics (cQED) allows spatially separated superconducting qubits to interact via a superconducting microwave cavity that acts as a 'quantum bus', making possible two-qubit entanglement and the implementation of simple quantum algorithms. Here we combine the cQED architecture with spin qubits by coupling an indium arsenide nanowire double quantum dot to a superconducting cavity. The architecture allows us to achieve a charge-cavity coupling rate of about 30 megahertz, consistent with coupling rates obtained in gallium arsenide quantum dots. Furthermore, the strong spin-orbit interaction of indium arsenide allows us to drive spin rotations electrically with a local gate electrode, and the charge-cavity interaction provides a measurement of the resulting spin dynamics. Our results demonstrate how the cQED architecture can be used as a sensitive probe of single-spin physics and that a spin-cavity coupling rate of about one megahertz is feasible, presenting the possibility of long-range spin coupling via superconducting microwave cavities.