WorldWideScience

Sample records for spin reorientation type

  1. Spinning in the scanner: neural correlates of virtual reorientation.

    Science.gov (United States)

    Sutton, Jennifer E; Joanisse, Marc F; Newcombe, Nora S

    2010-09-01

    Recent studies have used spatial reorientation task paradigms to identify underlying cognitive mechanisms of navigation in children, adults, and a range of animal species. Despite broad interest in this task across disciplines, little is known about the brain bases of reorientation. We used functional magnetic resonance imaging to examine neural activity in adults during a virtual reality version of the reorientation task. Three environments that varied in the cues provided were studied: a rectangular room with 4 identical gray walls (Geometry), a square room with 3 gray walls and 1 red wall (Feature), and a rectangular room with 3 gray walls and 1 red wall (Feature + Geometry). Multiple areas within the medial temporal lobe (MTL) showed increased activation when a feature was present compared with when reorientation was based only on geometric cues. In contrast, reliance on geometric cues significantly activated a number of non-MTL structures, including the prefrontal cortex and inferior temporal gyrus. These results provide neural evidence for processing differences between the 2 types of cue as well as insight into developmental and comparative aspects of reorientation. (c) 2010 APA, all rights reserved).

  2. Magnetooptical studies on spin-reorientation in rare earth orthoferrites

    International Nuclear Information System (INIS)

    Koshizuka, N.; Hayashi, K.; Suzuki, M.; Tsushima, T.

    1976-01-01

    Several types of spin-reorientation (SR) in some of the RFeO 3 are studied by Faraday rotation measurements; rotational SR of GAMMA 4 → GAMMA 2 type in (ErSm)FeO 3 , (Co 2+ , Ti 4+ ) doped YFeO 3 , and abrupt SR of GAMMA 4 → GAMMA 1 type in DyFeO 3 . Observations of SR by Faraday rotation were made in these crystals with incident light parallel to the optical axis. In relation with the decrease of Fe 3+ ion's anisotropy at T/sub SR/, an abrupt decrease of the coercive force are found in these systems. In general, Faraday rotation in RFeO 3 originates from Fe 3+ ions in the visible and near IR regions, while R 3+ ion's contribution to the Faraday rotation was observed for the wavelengths corresponding to the electronic transitions of R 3+ ions in ErFeO 3 and DyFeO 3 at low temperatures. In DyFeO 3 , a large contribution of Dy 3+ ions was observed at approximately 1.2 μm in the Faraday spectrum, and it is confirmed that the Dy 3+ moments are polarized along the c-axis in zero applied field above T/sub SR/. Magnetic field induced SR was also observed in DyFeO 3 , and the temperature dependence of the critical field was obtained as H/sub SR/ varies as absolute value T - T/sub SR/3/4

  3. 57Fe Moessbauer study of (Er1-xYx)2Fe14B spin reorientation

    International Nuclear Information System (INIS)

    Garitaonandia, J.S.; Barandiaran, J.M.; Orue, I.; Plazaola, F.; Ibarra, M.R.; Moral, A. del

    1995-01-01

    The 57 Fe Moessbauer spectra for (Er 1-x Y x ) 2 Fe 14 B compounds have been measured around the spin reorientation temperature and at reference temperature of 331 K, where all the samples have the same easy magnetization direction. This allows us to study the Y dilution and spin reorientation influence on the hyperfine parameters. ((orig.))

  4. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    Science.gov (United States)

    Vaknin, David; Zhang, Qiang; Peterson, Spencer; Dennis, Kevin; Tian, Wei

    2015-03-01

    Structure and complex magnetic properties of CeMnAsO, a parent compound of the ``1111''-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. Whereas there is no structural transition from the P4/nmm tetragonal phase below 420 K, CeMnAsO undergoes a C-type antiferromagnetic order with Mn2+ (S = 5 / 2) moments pointing along the c-axis below a relatively high Néel temperature of TN = 345 K. Below TSR = 35 K, two instantaneous transitions occur where the Mn moments reorient to the ab-plane preserving the C-type magnetic order, and Ce moments undergo long-range AFM ordering with moments in the ab-plane. Another transition to a noncollinear magnetic structure occurs below 7 K. We find that CeMnAsO primarily falls into the category of a local-moment antiferromagnetic insulator in which the nearest-neighbor interaction (J1) is dominant. The spin reorientation transition driven by the coupling between rare earth Ce and transition metal seems to be common to Mn, Fe and Cr ion,but not to Co and Ni ions in the iso-structural oxypnictides. Supported by the Office of Basic Energy Sciences, US-DOE, Number DE-AC02-07CH11358.

  5. Influence of the spin reorientation transition on the hysteresis characteristics of Nd-Fe-B film and bulk magnets

    International Nuclear Information System (INIS)

    Lileev, A.S.; Parilov, A.A.; Reissner, M.; Steiner, W.

    2004-01-01

    A comparison was made of the hysteresis characteristics of hard magnetic films with those of bulk samples based on Nd 2 Fe 14 B in the temperature range between 4.2 and 293 K. In both types of specimens characteristic 'dips' appear below 135 K in the demagnetisation curves which are caused by both the spin reorientation from easy axis to easy cone and the deviation from a perfect texture of the sample

  6. The spin-reorientation transition on Ni/Cu(0 0 1) surface covered with hydrogen

    International Nuclear Information System (INIS)

    Maca, F.; Shick, Alexander B.; Schneider, Guenter; Redinger, Josef

    2004-01-01

    We investigate the effect of an H-adlayer on the magnetic anisotropy energy (MAE) of Ni/Cu(0 0 1) making use of the total energy full-potential linearized augmented plane wave (FP-LAPW) method including spin-orbit coupling, and taking into account crystal structure relaxation effects. We find strong influence of H-adlayer on the surface MAE, providing the reduction of spin-reorientation transition critical thickness, in accordance with the recent experiments

  7. Macroscopic Magnetization Control by Symmetry Breaking of Photoinduced Spin Reorientation with Intense Terahertz Magnetic Near Field

    Science.gov (United States)

    Kurihara, Takayuki; Watanabe, Hiroshi; Nakajima, Makoto; Karube, Shutaro; Oto, Kenichi; Otani, YoshiChika; Suemoto, Tohru

    2018-03-01

    We exploit an intense terahertz magnetic near field combined with femtosecond laser excitation to break the symmetry of photoinduced spin reorientation paths in ErFeO3 . We succeed in aligning macroscopic magnetization reaching up to 80% of total magnetization in the sample to selectable orientations by adjusting the time delay between terahertz and optical pump pulses. The spin dynamics are well reproduced by equations of motion, including time-dependent magnetic potential. We show that the direction of the generated magnetization is determined by the transient direction of spin tilting and the magnetic field at the moment of photoexcitation.

  8. Influence of an electric field on the spin-reorientation transition in Ni/Cu(100)

    Energy Technology Data Exchange (ETDEWEB)

    Gerhard, Lukas [Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Bonell, Frédéric; Suzuki, Yoshishige [CREST, Japan Science Technology, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Wulfhekel, Wulf [Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany)

    2014-10-13

    Magnetoelectric coupling offers the possibility to change the magnetic state of a material by an applied electric field. Over the last few years, metallic systems have come up as simple prototypes for this interaction. While the previous studies focused on Fe and Co thin films or their alloys, here we demonstrate magnetoelectric coupling in a Ni thin film which is close to a spin-reorientation transition. Our magneto-optic Kerr effect measurements on 10 ML of Ni/Cu(100) show a considerable influence of the applied electric field on the magnetism. This rounds off the range of magnetic metals that exhibit magnetoelectric coupling, and it reveals the possibility of an electric field control of a spin-reorientation transition.

  9. Reversal magnetization, spin reorientation, and exchange bias in YCr O3 doped with praseodymium

    Science.gov (United States)

    Durán, A.; Escamilla, R.; Escudero, R.; Morales, F.; Verdín, E.

    2018-01-01

    Crystal structure, thermal properties, and magnetic properties were studied systematically in Y1 -xP rxCr O3 with 0.0 ≤x ≤0.3 compositions. Magnetic susceptibility and specific-heat measurements show an increase in the antiferromagnetic transition temperature (TN) as Pr is substituted in the Y sites and notable magnetic features are observed below TN. Strong coupling between magnetic and crystalline parameters is observed in a small range of Pr compositions. A small perturbation in the lattice parameters by a Pr ion is sufficient to induce a spin-reorientation transition followed by magnetization reversal to finally induce the exchange-bias effect. The spin-reorientation temperature (TSR) is increased from 35 to 149 K for 0.025 ≤x ≤0.1 compositions. It is found that the Cr spin sublattice rotates continuously from TSR to a new spin configuration at lower temperature. In addition, magnetization reversal is observed at T*˜35 K for x =0.05 up to T*˜63 K for x =0.20 composition. The M -H curves show a negative exchange-bias effect induced by Pr ions, which are observed below 100 K and are more intense at 5 K. At 10 K, the magnetic contribution of the specific heat as well as the ZFC magnetization show the rise of a peak with increasing Pr content. The magnetic anomaly could be associated with the freezing of the Pr magnetic moment randomly distributed at the 4 c crystallographic site. A clear correspondence between spin reorientation, magnetization reversal, and exchange-bias anisotropy with the tilting and octahedral distortion is also discussed.

  10. From non-linear magnetoacoustics and spin reorientation transition to magnetoelectric micro/nano-systems

    Science.gov (United States)

    Tiercelin, Nicolas; Preobrazhensky, Vladimir; BouMatar, Olivier; Talbi, Abdelkrim; Giordano, Stefano; Dusch, Yannick; Klimov, Alexey; Mathurin, Théo.; Elmazria, Omar; Hehn, Michel; Pernod, Philippe

    2017-09-01

    The interaction of a strongly nonlinear spin system with a crystalline lattice through magnetoelastic coupling results in significant modifications of the acoustic properties of magnetic materials, especially in the vicinity of magnetic instabilities associated with the spin-reorientation transition (SRT). The magnetoelastic coupling transfers the critical properties of the magnetic subsystem to the elastic one, which leads to a strong decrease of the sound velocity in the vicinity of the SRT, and allows a large control over acoustic nonlinearities. The general principles of the non-linear magneto-acoustics (NMA) will be introduced and illustrated in `bulk' applications such as acoustic wave phase conjugation, multi-phonon coupling, explosive instability of magneto-elastic vibrations, etc. The concept of the SRT coupled to magnetoelastic interaction has been transferred into nanostructured magnetoelastic multilayers with uni-axial anisotropy. The high sensitivity and the non-linear properties have been demonstrated in cantilever type actuators, and phenomena such as magneto-mechanical RF demodulation have been observed. The combination of the magnetic layers with piezoelectric materials also led to stress-mediated magnetoelectric (ME) composites with high ME coefficients, thanks to the SRT. The magnetoacoustic effects of the SRT have also been studied for surface acoustic waves propagating in the magnetoelastic layers and found to be promising for highly sensitive magnetic field sensors working at room temperature. On the other hand, mechanical stress is a very efficient way to control the magnetic subsystem. The principle of a very energy efficient stress-mediated magnetoelectric writing and reading in a magnetic memory is described.

  11. Magnetic stripe domains of [Pt/Co/Cu]10 multilayer near spin reorientation transition

    Directory of Open Access Journals (Sweden)

    L. Sun

    2016-05-01

    Full Text Available The dependence of magnetic anisotropy, magnetic domain patterns and magnetization reversal processes in [Pt/Co(tCo/Cu]10 film stack epitaxied on Cu (111 substrate have been studied as a function of the Co layer thickness tCo, by magneto-optic polar Kerr magnetometry and microscopy. We find the film undergoes spin reorientation transition from out-of-plane to in-plane as tCo increases. The SRT thickness is verified by Rotating-field Magneto-Optic Kerr effect method. The film exhibits the stripe domain structures at remanence with the width decreasing while tCo approaches SRT. As demonstrated by the first order reversal curve measurement, the magnetization reversal process encompasses irreversible domain nucleation, domain annihilation at large field and reversible domain switching near remanence.

  12. The influence of CO and H2 adsorption on the spin reorientation transition in Ni/Cu(001)

    NARCIS (Netherlands)

    van Dijken, S.; Vollmer, R.; Poelsema, Bene; Kirschner, J.

    2000-01-01

    A strong reduction of the critical thickness of the spin reorientation transition in Ni/Cu(0 0 1) has been observed when covered with CO or H2. For uncovered Ni films a critical thickness of 10.5 ML has been found at T=300 K. The critical thickness is reduced by about 3 and 4 ML after adsorption of

  13. Structural changes induced spin-reorientation of ultrathin Mn films grown on Ag(001)

    International Nuclear Information System (INIS)

    Ouarab, N.; Haroun, A.; Baadji, N.

    2016-01-01

    The strained body centered tetragonal (bct) Mn ultrathin film from lattice parameter a=2.89 Å to lattice value of 2.73 Å induces anti-ferromagnetic behavior between Mn layers. The magnetic easy axis of Mn film was demonstrated theoretically to switch from the in-plane to out-of-plane by magneto-optical Kerr effect investigation. By including spin–orbit coupling in full potential linearized augmented plane waves and linearized muffin-tin orbitals methods, manganese ultrathin film displays different magnetic behaviors and the spin-reorientation transition is shown to be correlated to these structural changes. The calculated magnetic moment of manganese planes are enhanced and reach a value of ~4.02 μ B . The polar magneto-optical Kerr effect is calculated for a photon energy range extended to 15 eV. It shows a pronounced peak in visible light. - Highlights: • The applied strain in Mn-bct structure induces anti-ferromagnetic behavior. • The easy magnetization axis is demonstrated to be out-of-plane. • The magnetic moment of Mn-layers are enhanced and reach a value of ~4.02 μ B . • Kerr spectra show significant polar responses for Mn films in the visible range. • The prominent structures in the Kerr spectra have been identified.

  14. Structural changes induced spin-reorientation of ultrathin Mn films grown on Ag(001)

    Energy Technology Data Exchange (ETDEWEB)

    Ouarab, N., E-mail: ouarab_nourdine@yahoo.fr [Quantum Physics and Dynamical Systems Laboratory, Ferhat Abbas University of Sétif (Algeria); Semiconductor Technology Research Center for Energetic-(CRTSE), 02, Bd Frantz Fanon Algiers, BP N° 140 (Algeria); Haroun, A. [Quantum Physics and Dynamical Systems Laboratory, Ferhat Abbas University of Sétif (Algeria); Baadji, N. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2016-12-01

    The strained body centered tetragonal (bct) Mn ultrathin film from lattice parameter a=2.89 Å to lattice value of 2.73 Å induces anti-ferromagnetic behavior between Mn layers. The magnetic easy axis of Mn film was demonstrated theoretically to switch from the in-plane to out-of-plane by magneto-optical Kerr effect investigation. By including spin–orbit coupling in full potential linearized augmented plane waves and linearized muffin-tin orbitals methods, manganese ultrathin film displays different magnetic behaviors and the spin-reorientation transition is shown to be correlated to these structural changes. The calculated magnetic moment of manganese planes are enhanced and reach a value of ~4.02 μ{sub B}. The polar magneto-optical Kerr effect is calculated for a photon energy range extended to 15 eV. It shows a pronounced peak in visible light. - Highlights: • The applied strain in Mn-bct structure induces anti-ferromagnetic behavior. • The easy magnetization axis is demonstrated to be out-of-plane. • The magnetic moment of Mn-layers are enhanced and reach a value of ~4.02 μ{sub B}. • Kerr spectra show significant polar responses for Mn films in the visible range. • The prominent structures in the Kerr spectra have been identified.

  15. Features peculiar to the acoustic properties of intermetallic SmFe2 in the spin reorientation region

    International Nuclear Information System (INIS)

    Artma, E.E.; Zinoveva, G.P.; Korolyov, A.V.; Gaviko, V.S.

    1991-01-01

    In polycrystalline specimens of intermetallic SmFe 2 the temperature dependences are measured of the sound velocity and of the sound absorption coefficients. By contrast with earlier investigations, anomalies are detected in the acoustic properties at two spin-reorientation temperatures rather than at one. The temperature dependences are characterized by a hysteresis. Possible causes of the observed anomalies in the acoustic properties of SmFe 2 are discussed. (orig.)

  16. Visual study of domain structure in the spin reorientation range for (BiTm)3(FeGa)5O15 epitaxial films

    International Nuclear Information System (INIS)

    Belyaeva, A.I.; Antonov, A.V.; Egiazaryan, G.S.; Yur'ev, V.P.

    1980-01-01

    Carried out is visual study of the domain structure of (BiTm) 3 (FeGa) 5 O 12 ferrite-garnet epitaxial film with induced one-axial anisotropy within a wide temperature range of 4.2-400 K. Found is hysteresicless spin-reorientation phase transition, related to anisotropy change (light axis type on the anisotropy of light plane tyre). Intermediade state, connected with this transition, is investigated. It is shown, that double structure within temperature range Tsub(room)>=T>=Tsub(ph.tr) can be considered as thermodynamically equilibrium one

  17. Transport and magnetic study of the spin reorientation transition in the Tb5(Si0.5Ge0.5)4 magnetocaloric compound

    International Nuclear Information System (INIS)

    Araujo, J P; Pereira, A M; Braga, M E; Pinto, R P; Teixeira, J M; Correia, F C; Sousa, J B; Morellon, L; Algarabel, P A; Magen, C; Ibarra, M R

    2005-01-01

    Detailed measurements of the electrical resistivity ρ(T), thermopower S(T) and magnetization of Tb 5 (Si 0.5 Ge 0.5 ) 4 in the vicinity of the spin reorientation transitions observed in this compound are reported. Our results indicate a complex spin reorientation process associated with three different lattice sites occupied by the Tb ions. We identify two critical transition temperatures: one at T SR 1 = 57 K, as previously reported, and a new one at T SR 2 = 40 K. A simple model based on an approximate magnetic anisotropy energy is presented; it gives a satisfactory qualitative description of the main features of the reorientation processes

  18. Detection of unusual spin reorientation induced by magnetic field in DyFeO3

    International Nuclear Information System (INIS)

    Balbashov, A.M.; Marchukov, P.Yu.; Nikolaev, I.V.; Rudashevskij, E.G.

    1988-01-01

    It is detected that in DyFeO 3 the vector of antiferromagnetism reorientates continuously in two mutually perpendicular planes, and transition from one plane into the other one is a first-order phase transformation

  19. Elastic and magnetoelastic properties of intermetallic compound NdCo5 in the spin-reorientation region

    International Nuclear Information System (INIS)

    Deryagin, A.V.; Kvashnin, G.M.; Kapitonov, A.M.

    1984-01-01

    By the ultrasonic method the temperature dependences of elastic constants of the NdCO 5 monocrystal in the temperature range (4.2 ...350) K are determined. In the spontaneous spin-reorientation (SR) region an anomalous behaviour of all NdCO 5 elastic constants is revealed. The dependence of velocities of longitudinal elastic waves propagation along hexagonal axis on the value and orientation of the magnetic field is investigated. The influence of the magnetoelastic interaction on SR boundaries and K 1 anisotropy constant is estimated. Magnetoelastic Bsub(a)sup(theta) and Bsub(c)sup(theta) constants are calculated

  20. Investigation of spin-reorientation phase transitions at surface and in volume of alpha-Fe sub 2 O sub 3 monocrystals

    CERN Document Server

    Kamzin, A S

    2002-01-01

    The magnetic structure of the surface layer and volume and the processes, observed by the spin-reorientation phase transition (SRPT), are studied in the direct comparison of the properties of the thin surface layer and the volume of the hematite (alpha-Fe sub 2 O sub 3) macroscopic crystals. The method of simultaneous gamma, X-ray and electron Moessbauer spectroscopy was used in the studies. The direct data on the existence of the transition layer on the hematite crystals surface are obtained. It is established, that the Morin-type SRPT in the sample volume occurs by a jump (the first-order phase transition). The SRPT in the surface layer as well as in the crystal volume is accompanied by formation of the intermediate state, wherein the low- and high-temperature phases coexist. The obtained experimental data on the SRPT mechanism in the surface layer agree well with the conclusions of the phenomenological theory

  1. Spin reorientation and giant low-temperature magnetostriction of polycrystalline NdFe1.9 compound

    Science.gov (United States)

    Tang, Y. M.; He, Y.; Huang, Y.; Zhang, L.; Tang, S. L.; Du, Y. W.

    2018-04-01

    The spin reorientation and magnetostriction of polycrystalline NdFe1.9 cubic Laves phase compound were investigated. A prominent transition from tetragonal symmetry to orthorhombic symmetry in NdFe1.9 compound was determined by X-ray crystallographic study. Meanwhile, a large spontaneous magnetostriction λ111 of ∼3100 ppm was detected at 15 K, which is larger than the theoretical value of 2000 ppm predicted by single-ion model. NdFe1.9 exhibits larger low-field magnetostriction than PrFe1.9 and TbFe1.9 at 5 K in the magnetic field range of H ≤ 13 kOe, which makes it a promising material for low-temperature applications. The present work might be helpful to discover inexpensive Nd-based high-performance magnetostrictive and even magnetoelectric materials for low-temperature applications.

  2. Spin reorientation and spin-flop transition in multiferroic manganites Y1-xTbxMnO3 (x = 0, 0.1, 0.2) single crystals

    Science.gov (United States)

    Li, H. N.; Huang, J. W.; Xiao, L. X.; Peng, L. P.; Wu, Y. Y.; Du, G. H.; Ouyang, Z. W.; Chen, B. R.; Xia, Z. C.

    2012-04-01

    We investigated the structure and magnetic properties of the multiferroic hexagonal manganite Y1-xTbxMnO3 (x = 0, 0.1, 0.2) single crystals. At 23 K, a Mn spin reorientation transition, which is not reported in the parent compound YMnO3, is observed in Y0.8Tb0.2MnO3. At a lower temperature, another new transition is observed in the doping system, which is attributed to the formation of long range antiferromagntic order of the doped Tb3+ moments. Based on the experimental results, we suggest that the effect of Tb doping is to bring about the increase of the Mn-O-Mn bond angle and the relief of the magnetic frustration. With increasing the doping level, for x = 0.2, when a magnetic field is applied parallel to the c axis, the field induced spin-flop transition is appeared, which indicates the reorientation of the Mn3+ moments along with the field-induced ferromagnetic ordering of the Tb3+ moments. These results suggest that the possibility of the Tb doping can change the magnetic structure and ferroelectricity properties of YMnO3.

  3. Magnetic-field dependence of strongly anisotropic spin reorientation transition in NdFeO3: a terahertz study.

    Science.gov (United States)

    Jiang, Junjie; Song, Gaibei; Wang, Dongyang; Jin, Zuanming; Tian, Zhen; Lin, Xian; Han, Jiaguang; Ma, Guohong; Cao, Shixun; Cheng, Zhenxiang

    2016-03-23

    One of the biggest challenges in spintronics is finding how to switch the magnetization of a material. One way of the spin switching is the spin reorientation transition (SRT), a switching of macroscopic magnetization rotated by 90°. The macroscopic magnetization in a NdFeO3 single crystal rotates from Γ4 to Γ2 via Γ24 as the temperature is decreased from 170 to 100 K, while it can be switched back to Γ4 again by increasing the temperature. However, the precise roles of the magnetic-field induced SRT are still unclear. By using terahertz time-domain spectroscopy (THz-TDS), here, we show that the magnetic-field induced SRT between Γ4 and Γ2 is strongly anisotropic, depending on the direction of the applied magnetic field. Our experimental results are well interpreted by the anisotropy of rare-earth Nd(3+) ion. Furthermore, we find that the critical magnetic-field required for SRT can be modified by changing the temperature. Our study suggests that the anisotropic SRT in NdFeO3 single crystal provides a platform to facilitate the potential applications in robust spin memory devices.

  4. X-ray circular magnetic dichroism as a probe of spin reorientation transitions in Nd2Fe14B and Er2Fe14B systems

    International Nuclear Information System (INIS)

    Chaboy, J.; Marcelli, A.; Garcia, L.M.; Bartolome, J.; Kuz'min, M.D.; Maruyama, H.; Kobayashi, K.; Kawata, H.; Iwazumi, T.

    1995-01-01

    We present the first experimental observation of spin reorientation phase transitions (SRT) with the X-Ray circular magnetic dichroism (XCMD) technique. Both the first-order SRT in Er 2 Fe 14 B and the second-order one in Nd 2 Fe 14 B have been clearly detected, demonstrating the feasibility of this technique for studying SRTs. ((orig.))

  5. Electric field triggering the spin reorientation and controlling the absorption and release of heat in the induced multiferroic compound EuTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Ribeiro, P. O.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; Sousa, V. S. R. de; Lopes, P. H. O.; Oliveira, N. A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro–UERJ, Rua São, Francisco Xavier, 524, 20550-013 Rio de Janeiro, Rio de Janerio (Brazil); Gama, S. [Departamento de Ciências Exatas e da Terra-UNIFESP, Diadema, 09971-270 Sao Paulo (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, Sao Paulo (Brazil)

    2015-12-28

    We report remarkable results due to the coupling between the magnetization and the electric field induced polarization in EuTiO{sub 3}. Using a microscopic model Hamiltonian to describe the three coupled sublattices, Eu-(spin-up), Eu-(spin-down), and Ti-(moment), the spin flop and spin reorientation phase transitions were described with and without the electric-magnetic coupling interaction. The external electric field can be used to tune the temperature of the spin reorientation phase transition T{sub SR} = T{sub SR}(E). When the T{sub SR} is tuned around the EuTiO{sub 3}—Néel temperature (T{sub N} = 5.5 K), an outstanding effect emerges in which EuTiO{sub 3} releases heat under magnetic field change. The electric field controlling the spin reorientation transition and the endo-exothermic processes are discussed through the microscopic interactions model parameters.

  6. Spin reorientation in α-Fe2O3 nanoparticles induced by interparticle exchange interactions in alpha-Fe2O3/NiO nanocomposites

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Lefmann, Kim; Lebech, Bente

    2011-01-01

    We report that the spin structure of alpha-Fe2O3 nanoparticles rotates coherently out of the basal (001) plane at low temperatures when interacting with thin plate-shaped NiO nanoparticles. The observed spin reorientation (up to similar to 70 degrees) in alpha-Fe2O3 nanoparticles has, in appearan......, similarities to the Morin transition in bulk alpha-Fe2O3, but its origin is different-it is caused by exchange coupling between aggregated nanoparticles of alpha-Fe2O3 and NiO with different directions of easy axes of magnetization....

  7. Spin re-orientation in magnetostatically coupled Ni(80)Fe(20) ellipsoidal nanomagnets.

    Science.gov (United States)

    Jain, S; Adeyeye, A O; Singh, N

    2010-07-16

    We investigate the influence of magnetostatic coupling on the spin configurations and magnetization reversal mechanism in a one-dimensional linear chain of densely packed Ni(80)Fe(20) ellipsoidal nanomagnets arranged in two basic configurations (elements coupled along the major or minor axes). Using magnetic force microscopy (MFM) we observed that for geometrically identical ellipsoidal nanomagnets the magnetic states at remanence are strongly dependent on the arrangement of the ellipsoid due to competition between the inherent shape and configuration anisotropies. When the elements are coupled along the major axis, the individual elements adopt a single domain magnetic state at remanence for field applied along the linear chain. This is in contrast with a wide range of magnetic states (single vortex states, double vortex states and modified single domain states) observed for elements coupled along the minor axis and also isolated elements. We have conducted a detailed investigation on the magnetization reversal mechanisms for both configurations and have correlated our experimental results with micromagnetic simulations.

  8. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    OpenAIRE

    Zhang, Qiang; Tian, Wei; Peterson, Spencer G.; Dennis, Kevin W.; Vaknin, David

    2014-01-01

    Structure and magnetic properties of high-quality polycrystlline CeMnAsO, a parent compound of the "1111"-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. We find that CeMnAsO undergoes a C-type antiferromagnetic order with Mn$^{2+}$ ($S=5/2$) moments pointing along the \\textit{c}-axis below a relatively high N\\'{e}el temperature of $T_{\\rm N} = 345$ K. Below $T_{\\rm SR} = 35$ K, two instantaneous transitions occur where the Mn moments...

  9. Micromagnetic analysis of spin-reorientation transitions. The role of magnetic domain structure

    Energy Technology Data Exchange (ETDEWEB)

    Skokov, Konstantin P., E-mail: skokov_k_p@mail.ru [Tver State University, Tver 170100 (Russian Federation); Physics Department, Chelyabinsk State University, Chelyabinsk 454001 (Russian Federation); Pastushenkov, Yury G., E-mail: yupast@mail.ru [Tver State University, Tver 170100 (Russian Federation); Taskaev, Sergey V., E-mail: tsv@csu.ru [Physics Department, Chelyabinsk State University, Chelyabinsk 454001 (Russian Federation); National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation); Rodionova, Valeria V., E-mail: valeriarodionova@gmail.com [National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation); Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation)

    2015-12-01

    A method for calculating micromagnetic state of ferro- or ferrimagnetic single-crystals based on the Néel's method of phases is proposed. The standard Néel technique requires different approaches to calculation of micromagnetic state of samples with different anisotropy types. Furthermore, this technique cannot be used to calculate magnetization curves of materials with a complex anisotropy type, in which the first-order magnetization process (FOMP) occurs. On the contrary, the technique proposed in the present work makes it possible to calculate micromagnetic state of a sample within one unified approach. This technique has no limitations in terms of the anisotropy type as well. In case of the FOMP, the simulation methods that we used show results different from conventional calculation methods. The reason is that the conventional methods imply coherent rotation of magnetization in single domain particle (so-called Stoner–Wohlfarth model). We explain this discrepancy by the fact that a magnetic domain structure appears in the region of the FOMP. In the present work we show that magnetization processes do not occur in a jump under the FOMP but gradually pass though nucleation and new high-field phase growing, which substitutes for the low-field phase.

  10. Micromagnetic analysis of spin-reorientation transitions. The role of magnetic domain structure

    International Nuclear Information System (INIS)

    Skokov, Konstantin P.; Pastushenkov, Yury G.; Taskaev, Sergey V.; Rodionova, Valeria V.

    2015-01-01

    A method for calculating micromagnetic state of ferro- or ferrimagnetic single-crystals based on the Néel's method of phases is proposed. The standard Néel technique requires different approaches to calculation of micromagnetic state of samples with different anisotropy types. Furthermore, this technique cannot be used to calculate magnetization curves of materials with a complex anisotropy type, in which the first-order magnetization process (FOMP) occurs. On the contrary, the technique proposed in the present work makes it possible to calculate micromagnetic state of a sample within one unified approach. This technique has no limitations in terms of the anisotropy type as well. In case of the FOMP, the simulation methods that we used show results different from conventional calculation methods. The reason is that the conventional methods imply coherent rotation of magnetization in single domain particle (so-called Stoner–Wohlfarth model). We explain this discrepancy by the fact that a magnetic domain structure appears in the region of the FOMP. In the present work we show that magnetization processes do not occur in a jump under the FOMP but gradually pass though nucleation and new high-field phase growing, which substitutes for the low-field phase.

  11. Spin reorientation and magnetoelastic properties of ferromagnetic T b1 -xN dxC o2 systems with a morphotropic phase boundary

    Science.gov (United States)

    Murtaza, Adil; Yang, Sen; Chang, Tieyan; Ghani, Awais; Khan, Muhammad Tahir; Zhang, Rui; Zhou, Chao; Song, Xiaoping; Suchomel, Matthew; Ren, Yang

    2018-03-01

    The spin reorientation (SR) and magnetoelastic properties of pseudobinary ferromagnetic T b1 -xN dxC o2 (0 ≤x ≤1.0 ) systems involving a morphotropic phase boundary (MPB) were studied by high-resolution synchrotron x-ray diffraction (XRD), magnetization, and magnetostriction measurements. The easy magnetization direction of the Laves phase lies along the 〈111 〉 axis with x 0.65 below Curie temperature (TC). The temperature-dependent magnetization curves showed SR; this can be explained by a two-sublattice model. Based on the synchrotron (XRD) and magnetization measurements, the SR phase diagram for a MPB composition of T b0.35N d0.65C o2 was obtained. Contrary to previously reported ferromagnetic systems involving MPB, the MPB composition of T b0.35N d0.65C o2 exhibits a low saturation magnetization (MS), indicating a compensation of the Tb and Nd magnetic moments at MPB. The anisotropic magnetostriction (λS) first decreased until x =0.8 and then continuously increased in the negative direction with further increase of Nd concentration. The decrease in magnetostriction can be attributed to the decrease of spontaneous magnetostriction λ111 and increase of λ100 with opposite sign to λ111. This paper indicates an anomalous type of MPB in the ferromagnetic T b1 -xN dxC o2 system and provides an active way to design novel functional materials with exotic properties.

  12. Perpendicular magnetic anisotropy, unconventional magnetization texture and extraordinary gradual spin reorientation transition of cobalt films in contact with graphene (Conference Presentation)

    Science.gov (United States)

    Rougemaille, Nicolas; Vu, Anh Duc; Chen, Gong; N'Diaye, Alpha T.; Schmid, Andreas K.; Coraux, Johann

    2016-10-01

    Owing to its peculiar electronic band structure, high carrier mobility and long spin diffusion length, graphene is a promising two-dimensional material for microelectronics and spintronics. Graphene also shows interesting magnetic properties when in contact with a ferromagnetic metal (FM). For instance, graphene carries a net magnetic moment when deposited on Fe/Ni(111), and a significant spin splitting can be induced in graphene due to proximity with a heavy element. While these results illustrate potential advantages of integrating graphene within a magnetic stack, the influence of graphene on the magnetic properties of a FM is still largely unexplored. In particular, non-magnetic overlayers generally affect the magnetic anisotropy energy (MAE) of thin layers, where interfaces play an important role. We can then wonder how an interface with graphene would influence the MAE of a thin FM film. Using spin-polarized low-energy electron microscopy, we study how a graphene overlayer affects the magnetic properties of atomically flat, nm-thick Co films grown on Ir(111). In this contribution, we report several astonishing magnetic properties of graphene-covered Co films: 1) Perpendicular magnetic anisotropy is favored over an unusually large thickness range, 2) Vectorial magnetic imaging reveals an extraordinarily gradual thickness-dependent spin reorientation transition (SRT), 3) During the SRT, cobalt films are characterized by an unconventional spin texture, 4) Spectroscopy measurements indicate that incident spin-polarized electrons do not suffer substantial spin-dependent collisions a few electron-Volts above the vacuum level. These properties strikingly differ from those of pristine cobalt films and could open new prospects in surface magnetism and spintronics.

  13. Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films

    NARCIS (Netherlands)

    Lisfi, A.; Williams, C.M.; Nguyen, L.T.; Lodder, J.C.; Coleman, A.; Corcoran, H.; Johnson, A.; Chang, P.; Abhishek Kumar, A.K.; Kumar, A.; Morgan, W.

    2007-01-01

    Spin reorientation has been observed in CoFe2O4 thin single crystalline films epitaxially grown on (100) MgO substrate upon varying the film thickness. The critical thickness for such a spin-reorientation transition was estimated to be 300 nm. The reorientation is driven by a structural transition

  14. Magnetotransport evidence for irreversible spin reorientation in the collinear antiferromagnetic state of underdoped Nd2 -xCexCuO4

    Science.gov (United States)

    Dorantes, A.; Alshemi, A.; Huang, Z.; Erb, A.; Helm, T.; Kartsovnik, M. V.

    2018-02-01

    We make use of the strong spin-charge coupling in the electron-doped cuprate Nd2 -xCexCuO4 to probe changes in its spin system via magnetotransport measurements. We present a detailed study of the out-of-plane magnetoresistance in underdoped single crystals of this compound, including the nonsuperconducting, 0.05 ≤x ≤0.115 , and superconducting, 0.12 ≤x ≤0.13 , compositions. Special focus is put on the dependence of the magnetoresistance on the field orientation in the plane of the CuO2 layers. In addition to the kink at the field-induced transition between the noncollinear and collinear antiferromagnetic configurations, a sharp irreversible feature is found in the angle-dependent magnetoresistance of all samples in the high-field regime, at field orientations around the Cu-O-Cu direction. The obtained behavior can be explained in terms of field-induced reorientation of Cu2 + spins within the collinear antiferromagnetic state. It is therefore considered an unambiguous indication of the long-range magnetic order.

  15. Spin relaxation through lateral spin transport in heavily doped n -type silicon

    Science.gov (United States)

    Ishikawa, M.; Oka, T.; Fujita, Y.; Sugiyama, H.; Saito, Y.; Hamaya, K.

    2017-03-01

    We experimentally study temperature-dependent spin relaxation including lateral spin diffusion in heavily doped n -type silicon (n+-Si ) layers by measuring nonlocal magnetoresistance in small-sized CoFe/MgO/Si lateral spin-valve (LSV) devices. Even at room temperature, we observe large spin signals, 50-fold the magnitude of those in previous works on n+-Si . By measuring spin signals in LSVs with various center-to-center distances between contacts, we reliably evaluate the temperature-dependent spin diffusion length (λSi) and spin lifetime (τSi). We find that the temperature dependence of τSi is affected by that of the diffusion constant in the n+-Si layers, meaning that it is important to understand the temperature dependence of the channel mobility. A possible origin of the temperature dependence of τSi is discussed in terms of the recent theories by Dery and co-workers.

  16. Ginzburg-Landau-type theory of nonpolarized spin superconductivity

    Science.gov (United States)

    Lv, Peng; Bao, Zhi-qiang; Guo, Ai-Min; Xie, X. C.; Sun, Qing-Feng

    2017-01-01

    Since the concept of spin superconductor was proposed, all the related studies concentrate on the spin-polarized case. Here, we generalize the study to the spin-non-polarized case. The free energy of nonpolarized spin superconductor is obtained, and Ginzburg-Landau-type equations are derived by using the variational method. These Ginzburg-Landau-type equations can be reduced to the spin-polarized case when the spin direction is fixed. Moreover, the expressions of super linear and angular spin currents inside the superconductor are derived. We demonstrate that the electric field induced by the super spin current is equal to the one induced by an equivalent charge obtained from the second Ginzburg-Landau-type equation, which shows self-consistency of our theory. By applying these Ginzburg-Landau-type equations, the effect of electric field on the superconductor is also studied. These results will help us get a better understanding of the spin superconductor and related topics such as the Bose-Einstein condensate of magnons and spin superfluidity.

  17. Reorientation of the diagonal double-stripe spin structure at Fe1+yTe bulk and thin-film surfaces

    Science.gov (United States)

    Hänke, Torben; Singh, Udai Raj; Cornils, Lasse; Manna, Sujit; Kamlapure, Anand; Bremholm, Martin; Hedegaard, Ellen Marie Jensen; Iversen, Bo Brummerstedt; Hofmann, Philip; Hu, Jin; Mao, Zhiqiang; Wiebe, Jens; Wiesendanger, Roland

    2017-01-01

    Establishing the relation between ubiquitous antiferromagnetism in the parent compounds of unconventional superconductors and their superconducting phase is important for understanding the complex physics in these materials. Going from bulk systems to thin films additionally affects their phase diagram. For Fe1+yTe, the parent compound of Fe1+ySe1-xTex superconductors, bulk-sensitive neutron diffraction revealed an in-plane oriented diagonal double-stripe antiferromagnetic spin structure. Here we show by spin-resolved scanning tunnelling microscopy that the spin direction at the surfaces of bulk Fe1+yTe and thin films grown on the topological insulator Bi2Te3 is canted out of the high-symmetry directions of the surface unit cell resulting in a perpendicular spin component, keeping the diagonal double-stripe order. As the magnetism of the Fe d-orbitals is intertwined with the superconducting pairing in Fe-based materials, our results imply that the superconducting properties at the surface of the related superconducting compounds might be different from the bulk.

  18. Tuning Magnetism of [MnSb4](9-) Cluster in Yb14MnSb11 through Chemical Substitutions on Yb Sites: Appearance and Disappearance of Spin Reorientation.

    Science.gov (United States)

    Hu, Yufei; Chen, Chih-Wei; Cao, Huibo; Makhmudov, F; Grebenkemper, Jason H; Abdusalyamova, M N; Morosan, Emilia; Kauzlarich, Susan M

    2016-09-28

    Single crystals of Yb14-xRExMnSb11 (0 iso-structural with Ca14AlSb11 (I41/acd), and their compositions were determined by wavelength-dispersive spectroscopy. Yb14MnSb11 is described as a partially screened d-metal Kondo system with the isolated [MnSb4](9-) tetrahedral cluster having a d(5) + hole configuration that results in four unpaired electrons measured in the ferromagnetically ordered phase. All of the Yb atoms in Yb14MnSb11 are present as Yb(2+), and the additional RE in Yb14-xRExMnSb11 is trivalent, contributing one additional electron to the structure and altering the magnetic properties. All compounds show ferromagnetic ordering in the range of 39-52 K attributed to the [MnSb4](9-) magnetic moment. Temperature-dependent DC magnetization measurements of Yb14-xPrxMnSb11 (0.44 ≤ x ≤ 0.56) show a sharp downturn right below the ferromagnetic transition temperature. Single-crystal neutron diffraction shows that this downturn is caused by a spin reorientation of the [MnSb4](9-) magnetic moments from the ab-plane to c-axis. The spin reorientation behavior, caused by large anisotropy, is also observed for similar x values of RE = Nd but not for RE = Sm or Gd at any value of x. In Pr-, Nd-, and Sm-substituted crystals, the saturation moments are consistent with ∼4 unpaired electrons attributed to [MnSb4](9-), indicating that local moments of Pr, Nd, and Sm do not contribute to the ferromagnetic order. In the case of RE = Pr, this is confirmed by neutron diffraction. In contrast, the magnetic measurements of RE = Gd show that the moments of Gd ferromagnetically order with the moments of [MnSb4](9-), and reduced screening of moments on Mn(2+) is evident. The sensitive variation of magnetic behavior is attributed to the various RE substitutions resulting in different interactions of the 4f-orbitals with the 3d-orbitals of Mn in the [MnSb4](9-) cluster conducted through 5p-orbitals of Sb.

  19. Spin reorientation transition in the Er.sub.2-x./sub.Fe1.sub.4+2x./sub.Si.sub.3./sub. single-crystal studied by the .sup.57./sup.Fe Mossbauer spectroscopy and magnetic measurements

    Czech Academy of Sciences Publication Activity Database

    Żukrowski, J.; Błachowski, A.; Ruebenbauer, K.; Przewoźnik, J.; Sitko, D.; Kim-Ngan, N.-T.H.; Tarnawski, Z.; Andreev, Alexander V.

    2008-01-01

    Roč. 103, č. 12 (2008), 123910/1-123910/8 ISSN 0021-8979 R&D Projects: GA ČR(CZ) GA202/06/0185 Grant - others:European Community(XE) SPO WKP 1.4.3 Institutional research plan: CEZ:AV0Z10100520 Keywords : spin reorientation * Moessbauer spectroscopy * magnetization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.201, year: 2008

  20. Electric field numerical simulation of disc type electrostatic spinning spinneret

    Science.gov (United States)

    Wei, L.; Deng, ZL; Qin, XH; Liang, ZY

    2018-01-01

    Electrospinning is a new type of free-end spinning built on electric field. Different from traditional single needle spinneret, in this study, a new disc type free surface spinneret is used to produce multiple jets, this will greatly improve production efficiency of nanofiber. The electric-field distribution of spinneret is the crux of the formation and trajectory of jets. In order to probe the electric field intensity of the disc type spinneret, computational software of Ansoft Maxwell 12 is adopted for a precise and intuitive analysis. The results showed that the whole round cambered surface of the spinning solution at edge of each layer of the spinneret with the maximum curvature has the highest electric field intensity, and through the simulation of the electric field distribution of different spinneret parameters such as layer, the height and radius of the spinneret. Influences of various parameters on the electrostatic spinning are obtained.

  1. Hydrostatic pressure effect on the spin reorientation transition of ferromagnetic Sm0.7-xLaxSr0.3MnO3 (x = 0, 0.1) polycrystals

    Science.gov (United States)

    Thiyagarajan, R.; Arumugam, S.; Sivaprakash, P.; Kannan, M.; Saravanan, C.; Yang, Wenge

    2017-06-01

    The hydrostatic pressure effect on the resistivity and magnetization of the narrow band gap manganite Sm0.7-xLaxSr0.3MnO3 (x = 0, 0.1) systems has been investigated. At ambient pressure measurements, the parent compound Sm0.7Sr0.3MnO3 showed a ferromagnetic-insulating nature, whereas the 10% La-doped compound Sm0.6La0.1Sr0.3MnO3 showed a ferromagnetic-metallic nature. Furthermore, both samples showed a spin-reorientation transition (TSR) below Curie temperature, which originated from the Mn sublattice and was supported by an antiferromagnetic Sm(4f)-Mn(3d) interaction. Both samples exhibited a normal and inverse magnetocaloric effect as a result of these two different magnetic transitions. Magnetization measurements on Sm0.7Sr0.3MnO3 under pressure did not show an appreciable change in the Curie temperature, but enhanced TSR, whereas an insulator-metallic transition was observed during resistivity measurements under pressure. On the other hand, for Sm0.6La0.1Sr0.3MnO3, TC increased and TSR reduced upon the application of pressure. The metallic nature which is observed at ambient pressure resistivity measurement was further enhanced with 97% of piezoresistance. The pressure did not change the normal magnetocaloric effect of Sm0.7Sr0.3MnO3, but increased it in Sm0.6La0.1Sr0.3MnO3. However, there was not much change in the inverse magnetocaloric effect of both compounds. These studies were analyzed based on the pressure effect on the activation energy and scattering interaction factors.

  2. Visually induced reorientation illusions

    Science.gov (United States)

    Howard, I. P.; Hu, G.; Oman, C. M. (Principal Investigator)

    2001-01-01

    It is known that rotation of a furnished room around the roll axis of erect subjects produces an illusion of 360 degrees self-rotation in many subjects. Exposure of erect subjects to stationary tilted visual frames or rooms produces only up to 20 degrees of illusory tilt. But, in studies using static tilted rooms, subjects remained erect and the body axis was not aligned with the room. We have revealed a new class of disorientation illusions that occur in many subjects when placed in a 90 degrees or 180 degrees tilted room containing polarised objects (familiar objects with tops and bottoms). For example, supine subjects looking up at a wall of the room feel upright in an upright room and their arms feel weightless when held out from the body. We call this the levitation illusion. We measured the incidence of 90 degrees or 180 degrees reorientation illusions in erect, supine, recumbent, and inverted subjects in a room tilted 90 degrees or 180 degrees. We report that reorientation illusions depend on the displacement of the visual scene rather than of the body. However, illusions are most likely to occur when the visual and body axes are congruent. When the axes are congruent, illusions are least likely to occur when subjects are prone rather than supine, recumbent, or inverted.

  3. Haldane-Shastry spin chains of BCN type

    International Nuclear Information System (INIS)

    Enciso, A.; Finkel, F.; Gonzalez-Lopez, A.; Rodriguez, M.A.

    2005-01-01

    We introduce four types of SU(2M+1) spin chains which can be regarded as the BCN versions of the celebrated Haldane-Shastry chain. These chains depend on two free parameters and, unlike the original Haldane-Shastry chain, their sites need not be equally spaced. We prove that all four chains are solvable by deriving an exact expression for their partition function using Polychronakos's 'freezing trick'. From this expression we deduce several properties of the spectrum, and advance a number of conjectures that hold for a wide range of values of the spin M and the number of particles. In particular, we conjecture that the level density is Gaussian, and provide a heuristic derivation of general formulas for the mean and the standard deviation of the energy

  4. Reorienting Hypnosis Education.

    Science.gov (United States)

    Alter, David S; Sugarman, Laurence Irwin

    2017-01-01

    The legacy model of professional clinical hypnosis training presents a restrictive frame increasingly incompatible with our evolving understanding of psychobiology, health, and care. Emerging science recognizes human experience not as disease and diagnosis, but as manifestations of individual, uniquely-endowed, adaptively self-regulating systems. Hypnosis is a particularly well-suited discipline for effecting beneficial change in this paradigm. Training in clinical hypnosis must progress from the current linearly-structured, diagnosis-based, reductionist model toward a more responsive, naturalistic, and client-centered curriculum in order to remain relevant and accessible to clinicians beginning to integrate it into their practices. To that end, this article extends Hope and Sugarman's (2015) thesis of hypnosis as a skill set for systemic perturbation and reorientation to consider what those skills may be, the principles on which they are based, and how they may be taught. Parsing a clinical vignette reveals how incorporation of novelty and uncertainty results in less restrictive and more naturalistic hypnotic encounters that, in response to client-generated cues, elicit psychophysiological plasticity. This disruptive hypnosis education and training framework extends the utility and benefit of applied clinical hypnosis.

  5. Spin injection in n-type resonant tunneling diodes.

    Science.gov (United States)

    Orsi Gordo, Vanessa; Herval, Leonilson Ks; Galeti, Helder Va; Gobato, Yara Galvão; Brasil, Maria Jsp; Marques, Gilmar E; Henini, Mohamed; Airey, Robert J

    2012-10-25

    We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X-). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to -88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers.

  6. Reorientational dynamics of water confined in zeolites.

    Science.gov (United States)

    Fogarty, Aoife C; Coudert, François-Xavier; Boutin, Anne; Laage, Damien

    2014-02-24

    We present a detailed molecular-dynamics study of water reorientation and hydrogen-bond dynamics in a strong confinement situation, within the narrow pores of an all-silica Linde type A (LTA) zeolite. Two water loadings of the zeolite are compared with the bulk case. Water dynamics are retarded in this extreme hydrophobic confinement and the slowdown is more pronounced at higher water loading. We show that water reorientation proceeds mainly by large-amplitude angular jumps, whose mechanism is similar to that determined in the bulk. The slowdown upon hydrophobic confinement arises predominantly from an excluded-volume effect on the large fraction of water molecules lying at the interface with the zeolite matrix, with an additional minor contribution coming from a structuring effect induced by the confinement. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Tectonic patterns on a reoriented planet - Mars

    International Nuclear Information System (INIS)

    Melosh, H.J.

    1980-01-01

    Both geological and free-air-gravity data suggest that the positive mass anomaly associated with the Tharsis volcanoes may have reoriented Mars' lithosphere by as much as 25 deg. Since Mars is oblate, rotation of the lithosphere over the equatorial bulge by 25 deg produces membrane stresses of several kilobars, large enough to initiate faulting. Plots of the magnitude and direction of stresses in a reoriented planet show that near Tharsis the dominant fault type should be north-south-trending normal faults. This normal fault province is centered at 30 deg N latitude and extends about 45 deg east and west in longitude. Similar faults should occur at the antipodes, north of Hellas Planitia

  8. Reorientation Histories of Mercury, Venus, the Moon, and Mars

    Science.gov (United States)

    Keane, J. T.; Matsuyama, I.

    2017-09-01

    The spins of planets are not constant with time. Impacts, volcanos, and other large geologic features can reorient planets (a process known as true polar wander). True polar wander can have important implications for the climate, volatiles, and tectonics of planets and moons. However, despite its importance, it has been difficult to study true polar wander for objects beyond the Earth. Here we present the results of the first comprehensive, data-driven investigation into the true polar wander histories of Mercury, Venus, the Moon, and Mars. We find that Mercury and the Moon have both reoriented in response to large impacts, while the spins of Mars and Venus are more strongly affected by volcanism. Venus, in particular, has been subject to some very dramatic episodes of true polar wander in the past.

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

    Science.gov (United States)

    Haze, Masahiro; Yoshida, Yasuo; Hasegawa, Yukio

    2017-10-16

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

  10. Continuous reorientation of synchronous terrestrial planets due to mantle convection

    Science.gov (United States)

    Leconte, Jérémy

    2018-02-01

    Many known rocky exoplanets are thought to have been spun down by tidal interactions to a state of synchronous rotation, in which a planet's period of rotation is equal to that of its orbit around its host star. Investigations into atmospheric and surface processes occurring on such exoplanets thus commonly assume that day and night sides are fixed with respect to the surface over geological timescales. Here we use an analytical model to show that true polar wander—where a planetary body's spin axis shifts relative to its surface because of changes in mass distribution—can continuously reorient a synchronous rocky exoplanet. As occurs on Earth, we find that even weak mantle convection in a rocky exoplanet can produce density heterogeneities within the mantle sufficient to reorient the planet. Moreover, we show that this reorientation is made very efficient by the slower rotation rate of a synchronous planet when compared with Earth, which limits the stabilizing effect of rotational and tidal deformations. Furthermore, a relatively weak lithosphere limits its ability to support remnant loads and stabilize against reorientation. Although uncertainties exist regarding the mantle and lithospheric evolution of these worlds, we suggest that the axes of smallest and largest moment of inertia of synchronous exoplanets with active mantle convection change continuously over time, but remain closely aligned with the star-planet and orbital axes, respectively.

  11. Genomic Signals of Reoriented ORFs

    Directory of Open Access Journals (Sweden)

    Paul Dan Cristea

    2004-01-01

    Full Text Available Complex representation of nucleotides is used to convert DNA sequences into complex digital genomic signals. The analysis of the cumulated phase and unwrapped phase of DNA genomic signals reveals large-scale features of eukaryote and prokaryote chromosomes that result from statistical regularities of base and base-pair distributions along DNA strands. By reorienting the chromosome coding regions, a “hidden” linear variation of the cumulated phase has been revealed, along with the conspicuous almost linear variation of the unwrapped phase. A model of chromosome longitudinal structure is inferred on these bases.

  12. Spin-splitting in p-type Ge devices

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, S. N., E-mail: s.holmes@crl.toshiba.co.uk; Newton, P. J.; Llandro, J.; Mansell, R.; Barnes, C. H. W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Morrison, C.; Myronov, M. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-08-28

    Compressively strained Ge quantum well devices have a spin-splitting in applied magnetic field that is entirely consistent with a Zeeman effect in the heavy hole valence band. The spin orientation is determined by the biaxial strain in the quantum well with the relaxed SiGe buffer layers and is quantized in the growth direction perpendicular to the conducting channel. The measured spin-splitting in the resistivity ρ{sub xx} agrees with the predictions of the Zeeman Hamiltonian where the Shubnikov-deHaas effect exhibits a loss of even filling factor minima in the resistivity ρ{sub xx} with hole depletion from a gate field, increasing disorder or increasing temperature. There is no measurable Rashba spin-orbit coupling irrespective of the structural inversion asymmetry of the confining potential in low p-doped or undoped Ge quantum wells from a density of 6 × 10{sup 10} cm{sup −2} in depletion mode to 1.7 × 10{sup 11} cm{sup −2} in enhancement.

  13. Thermocapillary reorientation of Janus drops

    Science.gov (United States)

    Rosales, Rodolfo; Saenz, Pedro

    2017-11-01

    Janus drops, named after the Ancient Roman two-faced god, are liquid drops formed from two immiscible fluids. Experimental observations indicate that a Janus drop may re-orientate in response to an applied external thermal gradient due to the Marangoni effect. Depending on the angle between the interior interface and the direction of the temperature gradient, disparities in the physical properties of the constituent liquids may lead to asymmetries in the thermocapillary flow. As a result, the drop will move along a curved path until a torque-free configuration is achieved, point after which it will continue on a straight trajectory. Here, we present the results of a theoretical investigation of this realignment phenomenon in the Stokes regime and in the limit of non-deformable interfaces. A 3D semi-analytical method in terms of polar spherical harmonics is developed to characterize and rationalize the hydrodynamic response (forces and torques), flow (velocity and temperature distribution) and trajectory of a Janus drop moving during the temperature-driven reorientation process. Furthermore, we discuss how this phenomenon may be exploited to develop dynamically reconfigurable micro-lenses. This work was partially supported by the US National Science Foundation through Grants DMS-1614043 and DMS-1719637.

  14. Spin dynamics in 122-type iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jitae

    2012-07-16

    In this thesis, we present the experimental data on four different iron-based SC materials. It is mainly about the magnetic-dynamics study in the FeSC that is assumed to be among the most crucial ingredients for superconductivity in this system. Thus, the main goal of this thesis is to figure out the exact relationship between spin dynamics and superconductivity, and then further to realize what is the contribution of magnetic fluctuations for superconductivity by providing experimental data for modeling a microscopic mechanism of electron pairing in the FeSC system. In Chap. 2, we first discuss basic characteristics of FeSC, such as crystal structure and electron band-structure by briefly reviewing the relevant literature. Then, an introduction about magnetic and SC phases will follow based on the generic phase diagram. Details about current understanding of magnetic ground state in the parent compounds will be discussed in terms of spin-wave excitations which would be important when we are considering the spin dynamics in doped materials. To study magnetic dynamics in FeSC, we employed the inelastic-neutron-scattering (INS) method which can uniquely probe the underlying spin dynamics in the four dimensional energy and momentum space in a wide range. By taking advantage of the well developed theory for the magnetic neutron-scattering process, one can quantify the imaginary part of spin susceptibility that is an essential physical quantity the description of elementary magnetic excitations and can be compared with theoretical calculations directly. Moreover, the technique's energy-resolving scale spans over the most relevant energy range of magnetic fluctuations (from 0 to 100 meV). For these reasons, neutron scattering is a very powerful technique for magnetism study, and we introduce how neutron-scattering experiment works theoretically and practically in Chap. 3. For a slightly underdoped Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} compound, we report the phase

  15. Spin dynamics in 122-type iron-based superconductors

    International Nuclear Information System (INIS)

    Park, Jitae

    2012-01-01

    In this thesis, we present the experimental data on four different iron-based SC materials. It is mainly about the magnetic-dynamics study in the FeSC that is assumed to be among the most crucial ingredients for superconductivity in this system. Thus, the main goal of this thesis is to figure out the exact relationship between spin dynamics and superconductivity, and then further to realize what is the contribution of magnetic fluctuations for superconductivity by providing experimental data for modeling a microscopic mechanism of electron pairing in the FeSC system. In Chap. 2, we first discuss basic characteristics of FeSC, such as crystal structure and electron band-structure by briefly reviewing the relevant literature. Then, an introduction about magnetic and SC phases will follow based on the generic phase diagram. Details about current understanding of magnetic ground state in the parent compounds will be discussed in terms of spin-wave excitations which would be important when we are considering the spin dynamics in doped materials. To study magnetic dynamics in FeSC, we employed the inelastic-neutron-scattering (INS) method which can uniquely probe the underlying spin dynamics in the four dimensional energy and momentum space in a wide range. By taking advantage of the well developed theory for the magnetic neutron-scattering process, one can quantify the imaginary part of spin susceptibility that is an essential physical quantity the description of elementary magnetic excitations and can be compared with theoretical calculations directly. Moreover, the technique's energy-resolving scale spans over the most relevant energy range of magnetic fluctuations (from 0 to 100 meV). For these reasons, neutron scattering is a very powerful technique for magnetism study, and we introduce how neutron-scattering experiment works theoretically and practically in Chap. 3. For a slightly underdoped Ba 1-x K x Fe 2 As 2 compound, we report the phase separation between

  16. Early-type Galaxy Spin Evolution in the Horizon-AGN Simulation

    Science.gov (United States)

    Choi, Hoseung; Yi, Sukyoung K.; Dubois, Yohan; Kimm, Taysun; Devriendt, Julien. E. G.; Pichon, Christophe

    2018-04-01

    Using the Horizon-AGN simulation data, we study the relative role of mergers and environmental effects in shaping the spin of early-type galaxies (ETGs) after z ≃ 1. We follow the spin evolution of 10,037 color-selected ETGs more massive than {10}10 {M}ȯ that are divided into four groups: cluster centrals (3%), cluster satellites (33%), group centrals (5%), and field ETGs (59%). We find a strong mass dependence of the slow rotator fraction, f SR, and the mean spin of massive ETGs. Although we do not find a clear environmental dependence of f SR, a weak trend is seen in the mean value of the spin parameter driven by the satellite ETGs as they gradually lose their spin as their environment becomes denser. Galaxy mergers appear to be the main cause of total spin changes in 94% of the central ETGs of halos with {M}vir}> {10}12.5 {M}ȯ , but only 22% of satellite and field ETGs. We find that non-merger-induced tidal perturbations better correlate with the galaxy spin down in satellite ETGs than in mergers. Given that the majority of ETGs are not central in dense environments, we conclude that non-merger tidal perturbation effects played a key role in the spin evolution of ETGs observed in the local (z < 1) universe.

  17. Spin Waves in Magnetic Thin Films: New Types of Solitons and Electrical Control

    Science.gov (United States)

    Wang, Zihui

    New types of spin-wave solitons in magnetic thin films and the methods to control spin waves electrically are studied in this thesis. In the first part, the first observation of chaotic spin-wave solitons in yttrium iron garnet (YIG) thin film-based active feedback rings is presented. At some ring gain levels, one observes the self-generation of a single spin-wave soliton pulse in the ring. When the pulse circulates in the ring, its amplitude varies chaotically with time. The excitation of dark spin-wave envelope solitons in YIG thin film strips is also described. The formation of a pair of black solitons with a phase jump of 180° is observed for the first time. The excitation of bright solitons in the case of repulsive nonlinearity is also observed and is reproduced by a numerical simulation based on a high-order nonlinear Schrodinger equation. In the second part, the control of magnetization relaxation in ferromagnetic insulators via interfacial spin scattering is presented. In the experiments nanometer-thick YIG/Pt bi-layered structures are used, with the Pt layer biased by an electric voltage. The bias voltage produces a spin current across the Pt layer thickness due to the spin Hall effect. As this current scatters off the YIG surface, it exerts a torque on the YIG surface spins. This torque can reduce or increase the damping and thereby compress or broaden the ferromagnetic resonance linewidth of the YIG film, depending on the field/current configuration. The control of spin waves in a YIG thin film via interfacial spin scattering is also presented. In the experiments a 4.6-microm-thick YIG film strip with a 20-nm-thick Pt capping layer is used. A DC current pulse is applied to the Pt layer and produced a spin current across the Pt layer. As the spin current scatters off the YIG surface, it can either amplify or attenuate spin-wave pulses that travel in the YIG strip, depending on the current/field configuration.

  18. New-type spin polarized electron source and its applications; Atarashii spin henkyoku denshi sengen to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Saka, T.; Kato, T. [Daido Steel Co. Ltd., Nagoya (Japan); Nakanishi, T.; Okumi, S. [Nagoya University, Nagoya (Japan); Horinaka, H. [Osaka Prefectural University, Osaka (Japan). College of Engineering

    1998-08-20

    This paper reveals that using distorted thin GaAs film can realize high polarization in spin polarized electron ray, and introduces properties of the developed ray source. The paper also touches on the application thereof to property physics. Realization of the high spin polarization is based on use of the `optical polarization method`. With this method, electrons in specific spin state are excited into a conduction band by utilizing the selection law used when valency electrons of zincblende type crystal such as GaAs absorb circular polarization. These electrons are taken out into vacuum and used as polarized electron beams. In order to realize uniformly distorted GaAs film, a method was discussed, with which the thin GaAs films are grown on substrates with different lattice constants, and the films are distorted by means of lattice mismatch. GaAs(1-x)Px was used for the substrates. GaAs(1-x)Px has the lattice constant decrease as the P`s mixed crystal ratio `x` increases. If a thin GaAs film is grown on this substrate, it is possible to obtain GaAs which is subjected to compression stress in the direction parallel with the growing surface, and tensile stress in the vertical direction. 13 refs., 5 figs., 1 tab.

  19. Observations of exciton and carrier spin relaxation in Be doped p-type GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Asaka, Naohiro; Harasawa, Ryo; Tackeuchi, Atsushi, E-mail: atacke@waseda.jp [Department of Applied Physics, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Lu, Shulong; Dai, Pan [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Dushu Lake Higher Education Town, Ruoshui Road 398, Suzhou Industrial Park, Suzhou 215028 (China)

    2014-03-17

    We have investigated the exciton and carrier spin relaxation in Be-doped p-type GaAs. Time-resolved spin-dependent photoluminescence (PL) measurements revealed spin relaxation behaviors between 10 and 100 K. Two PL peaks were observed at 1.511 eV (peak 1) and 1.497 eV (peak 2) at 10 K, and are attributed to the recombination of excitons bound to neutral Be acceptors (peak 1) and the band-to-acceptor transition (peak 2). The spin relaxation times of both PL peaks were measured to be 1.3–3.1 ns at 10–100 K, and found to originate from common electron spin relaxation. The observed existence of a carrier density dependence of the spin relaxation time at 10–77 K indicates that the Bir-Aronov-Pikus process is the dominant spin relaxation mechanism.

  20. Generalized reorientation cross section for cylindrically symmetric velocity distributions

    International Nuclear Information System (INIS)

    Generalized reorientation cross sections are derived for the case of atom--molecule collisions where the molecules initially have a velocity distribution cylindrically symmetric about an axis in the laboratory reference frame. This spatial ordering of the velocity can come about, for instance, by exciting molecular electronic states with a light source whose linewidth is much narrower than the Doppler-broadened absorption line. A simple kinetic theory can be set up in terms of state multipoles that are not completely irreducible; the resulting reorientation cross sections are only slightly more complex than the cross sections occurring in a spherically symmetric velocity field. Two approximations are investigated: a McGuire--Kouri m/sub j/-conserving model and a semiclassical model where the orientation of the rotation plane is conserved. The import of the generalized cross sections for several types of experiment and the applicability of the approximate models are discussed

  1. Coherent Zeeman resonance from electron spin coherence in a mixed-type GaAs/AlAs quantum well.

    Science.gov (United States)

    O'Leary, Shannon; Wang, Hailin; Prineas, John P

    2007-03-01

    Coherent Zeeman resonance from electron spin coherence is demonstrated in a Lambda-type three-level system, coupling electron spin states via trions. The optical control of electron density that is characteristic of a mixed-type quantum-well facilitates the study of trion formation as well as the effects of many-body interactions on the manifestation of electron spin coherence in the nonlinear optical response.

  2. Spin-Orbital Correlated Dynamics in the Spinel-Type Vanadium Oxide MnV2 O4

    Science.gov (United States)

    Matsuura, Keisuke; Sagayama, Hajime; Uehara, Amane; Nii, Yoichi; Kajimoto, Ryoichi; Kamazawa, Kazuya; Ikeuchi, Kazuhiko; Ji, Sungdae; Abe, Nobuyuki; Arima, Taka-hisa

    2017-07-01

    We investigate the magnetic dynamics in the spinel-type vanadium oxide MnV2 O4 . Inelastic neutron scattering around 10 meV and a Heisenberg model analysis have revealed that V3 + spin-wave modes exist at a lower-energy region than previously reported. The scattering around 20 meV cannot be reproduced with the spin-wave analysis. We propose that this scattering could originate from the spin-orbital coupled excitation. This scattering is most likely attributable to V3 + spin-wave modes, entangled with the orbital hybridization between t2 g orbitals.

  3. Spin Structures in Magnetic Nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Brok, Erik; Frandsen, Cathrine

    2013-01-01

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

  4. Design of Spin-Frustrated Monomer-Type C60•− Mott Insulator

    Directory of Open Access Journals (Sweden)

    Akihiro Otsuka

    2018-02-01

    Full Text Available Spin-frustrated monomer-type Mott insulator C60•− solids are discussed in this review article. For the C60•− solids, the interfullerene center-to-center distance (r is the key parameter that controls the competition between covalent bond-formation, itinerancy, and spin frustration. Eight C60•− salts with various compositions and dimensionalities are reviewed. In all of these C60•− salts except one, neither bond-formation nor long-range magnetic ordering was observed down to low temperatures. A plot of Weiss temperature (|ΘCW| against r shows that |ΘCW| grows rapidly below r = 10.0 Å.

  5. The reorientation of spatial planning in Denmark

    DEFF Research Database (Denmark)

    Galland, Daniel

    2011-01-01

    has been reoriented at national, regional and urban/local levels over time. The fundamental objective of the project is hence to explore and examine the history and evolution of Danish spatial planning through three embedded case studies from inception until most recent transformations. Respectively......Danish spatial planning has been celebrated throughout Europe in view of its perceived values, qualities and undertakings. Yet, in essence, the Danish planning domain has been increasingly subjected to profound reorientations within the course of the past two decades. The intrinsic...... comprehensiveness and integration that once characterised planning policies and institutional practices occurring within and across the different administrative levels that constitute the Danish planning system have long since been at stake. Accordingly, the social and welfarist rationales behind spatial planning...

  6. Assessing affective variability in eating disorders: affect spins less in anorexia nervosa of the restrictive type.

    Science.gov (United States)

    Vansteelandt, Kristof; Probst, Michel; Pieters, Guido

    2013-08-01

    Differences in affective variability in eating disorders are examined using an ecological momentary assessment (EMA) protocol. It is hypothesized that restriction serves to pre-empt the activation of affect whereas bulimic behavior serves to cope with overwhelming affect once activated. Therefore, we expect anorexia nervosa (AN) patients of the restricting type (AN-RT) to have lower mean levels of affect and less affective variability than Bulimia Nervosa (BN) patients. Patients' successive affective states over time are represented as different positions in a two-dimensional space defined by the orthogonal dimensions of valence and activation. Affective variability is measured by the within person variance and the new concepts of pulse and spin. Results of this exploratory study suggest that the diagnostic groups have the same mean levels of affect but affect spins less in patients with AN-RT. Using an EMA protocol and measures like pulse and spin may reveal insights in eating disorders that remain hidden with more traditional assessment methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Pelvic reorientation osteotomies and acetabuloplasties in children. Surgical technique.

    Science.gov (United States)

    Sales de Gauzy, J

    2010-11-01

    The objectives of pelvic osteotomies are to improve femoral head coverage and coxofemoral joint stability. The most currently used osteotomies can be divided into reorientation osteotomies (Salter and Pol le Cœur triple osteotomy) and acetabuloplasties (Pemberton and Dega). All these osteotomies share an identical installation on the table and bikini-type incision. The Salter osteotomy uses a single osteotomy line located at the inferior gluteal line. The Pol Le Cœur triple pelvic osteotomy combines innominate osteotomies of the iliopubic and ischiopubic rami via a genitofemoral approach (inguinal). In these two reorientation osteotomies, the acetabulum tilts in retroversion, improving the anterior and lateral coverage but reducing the posterior coverage. In the Pemberton acetabuloplasty, the osteotomy line is incomplete. It begins anteriorly between the iliac spines and ends posteriorly immediately above the triradiate cartilage. The posterior part of the ilium remains intact. The Pemberton acetabuloplasty causes retroversion and plicature of the acetabulum responsible for reducing its diameter. Anterior and lateral coverage of the femoral head is improved and posterior coverage remains unchanged. In the Dega acetabuloplasty, the osteotomy line is incomplete. It begins laterally above the acetabulum and terminates just above the triradiate cartilage. The medial part of the ilium remains intact. The Dega acetabuloplasty reduces the diameter of the acetabulum and improves overall femoral head coverage (anterior, lateral, and posterior). Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  8. Spin-State-Selective Excitation. Application for E.COSY-Type Measurement of JHHCoupling Constants

    Science.gov (United States)

    Meissner, Axel; Duus, Jens ø.; Sørensen, Ole Winneche

    1997-09-01

    A new pulse sequence element, spin-state-selective excitation (S3E), is introduced and combined with E.COSY-type techniques for measurement of1H-1HJcoupling constants. S3E edits the two resonances of a doublet prior to an evolution period of a multidimensional experiment and results in a subspectrum for each resonance. Due to this editing the large heteronuclear one-bond coupling constants normally exploited for separation of submultiplets in E.COSY-type experiments can be suppressed in experiments employing S3E. Hence there is a concomitant effective increase in resolution. Apart from pulse imperfections and relaxation during a delay (4J)-1S3E causes no loss of sensitivity in comparison to conventional experiments. Experimental confirmation is done using the protein RAP 17-97 (N-terminal domain of α2-macroglobulin receptor associated protein).

  9. Curci-Ferrari-type condition in Hamiltonian formalism: A free spinning relativistic particle

    Science.gov (United States)

    Shukla, A.; Bhanja, T.; Malik, R. P.

    2013-03-01

    The Curci-Ferrari (CF)-type restriction emerges in the description of a free spinning relativistic particle within the framework of the Becchi-Rouet-Stora-Tyutin (BRST) formalism when the off-shell nilpotent and absolutely anticommuting (anti-)BRST symmetry transformations for this system are derived from the application of the horizontality condition (HC) and its supersymmetric generalization (SUSY-HC) within the framework of the superfield formalism. We show that the above CF condition, which turns out to be the secondary constraint of our present theory, remains time-evolution invariant within the framework of Hamiltonian formalism. This time-evolution invariance i) physically justifies the imposition of the (anti-)BRST invariant CF-type condition on this system, and ii) mathematically implies the linear independence of BRST and anti-BRST symmetries of our present theory.

  10. Stress induced reorientation of vanadium hydride

    International Nuclear Information System (INIS)

    Beardsley, M.B.

    1977-10-01

    The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180 0 to 280 0 K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch

  11. Reorientation in combined stress induced martensite?

    International Nuclear Information System (INIS)

    Sittner, P.; Tokuda, M.

    1995-01-01

    The thermoelastic martensitic transformation induced by independent external forces has been investigated in combined tension-torsion experiments with Cu-Al-Zn-Mn SMA hollow bar polycrystals. When the nonproportional change of the applied stress (reloading) occurs at low volume fraction of stress induced martensite phase, the shape of the experimental transformation path suggests, that the forward or reverse stress induced martensitic transformations take place, depending whether the mechanical energy is being supplied or released. At higher volume fraction of martensite, the deformation behavior upon reloading becomes more complex, suggesting a possible role of martensite to martensite transformations or reorientation processes. (orig.)

  12. The effect of the single-spin defect on the stability of the in-plane vortex state in 2D magnetic nanodots

    International Nuclear Information System (INIS)

    Mamica, S.; Lévy, J.-C. S.; Depondt, Ph.; Krawczyk, M.

    2011-01-01

    The aim of this study is to analyse the stability of the single in-plane vortex state in two-dimensional magnetic nanodots with a nonmagnetic impurity (single-spin defect) at the centre. Small square and circular dots including up to a few thousand of spins are studied by means of a microscopic theory with nearest-neighbour exchange interactions and dipolar interactions fully taken into account. We calculate the spin-wave frequencies versus the dipolar-to-exchange interaction ratio d to find the values of d for which the assumed state is stable. Transitions to other states and their dependence on d and the vortex size are investigated as well, with two types of transition found: vortex core formation for small d values (strong exchange interactions), and in-plane reorientation of spins for large d values (strong dipolar interactions). Various types of localized spin waves responsible for these transitions are identified.

  13. Spin Resonance in the New-Structure-Type Iron-Based Superconductor CaKFe4As4

    Science.gov (United States)

    Iida, Kazuki; Ishikado, Motoyuki; Nagai, Yuki; Yoshida, Hiroyuki; Christianson, Andrew D.; Murai, Naoki; Kawashima, Kenji; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Iyo, Akira

    2017-09-01

    The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe4As4 was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at Qres = 1.17(1) Å-1, corresponding to the (π ,π ) nesting wave vector in tetragonal notation, evolves below Tc. The characteristic energy of the spin resonance Eres = 12.5 meV is smaller than twice the size of the superconducting gap (2Δ). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations, in which the different superconducting gaps on different Fermi surfaces are taken into account. Our INS and PRA studies demonstrate that the superconducting pairing nature in CaKFe4As4 is the s± symmetry.

  14. Effective Parenting and Socialization for Value Re-Orientation in ...

    African Journals Online (AJOL)

    The paper discusses the meaning/concept and nature of parenting, effective parenting, some problems of parenting in Nigeria, socialization as a medium of value inculcation and value reorientation. The paper believes that value reorientation in Nigeria is a feasible project that can only be attained through the enforcement ...

  15. Pluto followed its heart: reorientation and faulting of Pluto due to volatile loading in Sputnik Planum

    Science.gov (United States)

    Tuttle Keane, James; Matsuyama, Isamu; Kamata, Shunichi; Steckloff, Jordan

    2016-10-01

    The New Horizons flyby of Pluto revealed the dwarf planet to be a strikingly diverse, geologically active world. Perhaps the most intriguing feature on the New Horizons encounter hemisphere is Sputnik Planum—a 1000 km diameter, probable impact basin, filled with several kilometers of actively convecting volatile ices (N2, CH4, CO). One salient characteristic of Sputnik Planum is its curious alignment with the Pluto-Charon tidal axis. The alignment of large geologic features with principal axis of inertia (such as the tidal axis) is the hallmark of global reorientation, i.e. true polar wander. Here we show that the present location of Sputnik Planum is a natural consequence of loading of 1-2 km of volatile ices within the Sputnik Planum basin. Larger volatile ice thicknesses (like those inferred from studies of ice convection within Sputnik Planum) betray an underlying negative gravity anomaly associated with the basin. As Pluto reoriented in response to the loading of volatile ices within Sputnik Planum, stresses accumulated within the lithosphere (as each geographic location experiences a change in tidal/rotational potential). These reorientation stresses, coupled with loading stresses, and stresses from the freezing of a subsurface ocean resulted in the fracturing of Pluto's lithosphere in a characteristic, global pattern of extensional faults. Our predicted pattern of extensional faults due to this reorientation closely replicates the observed distribution of faults on Pluto (more so than global expansion, orbit migration, de-spinning, or loading alone). Sputnik Planum likely formed ~60° northwest of its present location, and was loaded with volatile ices over millions of years due to seasonal volatile transport cycles. This result places Pluto in a truly unique category of planetary bodies where volatiles are not only controlling surface geology and atmospheric processes, but they are also directly controlling the orientation of the entire dwarf planet

  16. Magnetic structure of MgCu2O3 and doping-induced spin reorientation in Mg1-x/2LixCu2-x/2O3

    DEFF Research Database (Denmark)

    Winkelmann, M.; Graf, H.A.; Andersen, N.H.

    1994-01-01

    is similar to the one producing an infinitely degenerate state in antiferromagnetic fcc lattices. Doping experiments with Li clearly demonstrate the importance of spin fluctuations and fluctuations of the local exchange fields for lifting the degeneracy in such a system. A remarkably small amount of Li...... (about 2 mole % Li) is sufficient to disturb the magnetic lattice in such a way that the almost collinear spin arrangement changes into an arrangement where the spins of one sublattice are strongly canted with respect to the spins of the other sublattice....

  17. Charge transport in 2DEG/s-wave superconductor junction with Dresselhaus-type spin-orbit coupling

    International Nuclear Information System (INIS)

    Sawa, Y.; Yokoyama, T.; Tanaka, Y.

    2007-01-01

    We study spin-dependent charge transport in superconducting junctions. We consider ballistic two-dimensional electron gas (2DEG)/s-wave superconductor junctions with Dresselhaus-type spin-orbit coupling (DSOC). We calculate the conductance normalized by that in the normal state of superconductor in order to study the effect of DSOC in 2DEG on conductance, changing the height of insulating barrier. We find the DSOC suppresses the conductance for low insulating barrier, while it can slightly enhance the conductance for high insulating barrier. It has a reentrant dependence on DSOC for middle strength insulating barrier. The effect of DSOC is weaken as the insulating barrier becomes high

  18. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    KAUST Repository

    Gan, Liyong

    2013-09-26

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  19. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-17

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  20. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2011-01-01

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  1. Vortex motion in type II superconductors probed by muon spin rotation and SANS

    Science.gov (United States)

    Forgan, E. M.; Charalambous, D.; Kealey, P. G.; King, P. J. C.; Khasanov, R.; Amato, A.

    2003-02-01

    We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low Tc type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbour FLL direction. This tends to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo technique to observe the energy change of neutrons diffracted by moving flux lines. The μSR technique gives the distribution of values of magnetic field within the FLL. We have recently shown that one can perform μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors.

  2. Vortex motion in type II superconductors probed by muon spin rotation and SANS

    International Nuclear Information System (INIS)

    Forgan, E.M.; Charalambous, D.; Kealey, P.G.; King, P.J.C.; Khasanov, R.; Amato, A.

    2003-01-01

    We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low T c type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbour FLL direction. This tends to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo technique to observe the energy change of neutrons diffracted by moving flux lines. The μSR technique gives the distribution of values of magnetic field within the FLL. We have recently shown that one can perform μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors

  3. Comparative Design, Scaling, and Control of Appendages for Inertial Reorientation

    OpenAIRE

    Libby, Thomas; Johnson, Aaron M.; Chang-Siu, Evan; Full, Robert J.; Koditschek, D. E.

    2015-01-01

    This paper develops a comparative framework for the design of actuated inertial appendages for planar, aerial reorientation. We define the Inertial Reorientation template, the simplest model of this behavior, and leverage its linear dynamics to reveal the design constraints linking a task with the body designs capable of completing it. As practicable inertial appendage designs lead to morphology that is generally more complex, we advance a notion of "anchoring" whereby a judicious choice of p...

  4. Impact of dopant concentrations on emitter formation with spin on dopant source in n-type crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Singha, Bandana; Solanki, Chetan Singh [Department of Energy Science and Technology, Indian Institute of Technology, Bombay Mumbai-400076, Maharashtra (India)

    2016-05-06

    Use of a suitable dopant source for emitter formation is an essential requirement in n-type crystalline silicon solar cells. Boron spin on dopant source, used as alternative to mostly used BBr{sub 3} liquid source, can yield an emitter with less diffusion induced defects under controlled conditions. Different concentrations of commercially available spin on dopant source is used and optimized in this work for sheet resistance values of the emitter ranging from 30 Ω/□ to 70 Ω/□ with emitter doping concentrations suitable for ohmic contacts. The dopant concentrations diluted with different ratios improves the carrier lifetime and thus improves the emitter performance. Hence use of suitable dopant source is essential in forming emitters in n-type crystalline silicon solar cells.

  5. Direct and two-phonon Orbach-Aminov type spin-lattice relaxation in molecular magnet V15

    Science.gov (United States)

    Tarantul, Alex; Tsukerblat, Boris

    2011-10-01

    In this article we propose a model of spin-phonon relaxation in K6[VIV 15As6O42(H2O)]-8H2O, the so called V15 cluster exhibiting the unique layered magnetic structure. The work is motivated by the recent observation of the Rabi oscillation [1] in this system and aimed to elucidate the role of spin-phonon interaction as a source of decoherence. The spin-phonon coupling is assumed to appear as a result of the modulation of the isotropic and antisymmetric (Dzyaloshinsky-Moriya) exchange interactions in the central triangular layer of vanadium ions by the acoustic lattice vibrations. The relaxation rates are estimated within the Debye model for the lattice vibrations. Within the pseudo-angular momentum representation the selection rules for the direct (one-phonon) transitions between Zeeman levels are derived and a special role of the antisymmetric exchange is underlined. The probabilities of the two-phonon Orbach-Aminov type processes are evaluated as well, while the Raman type relaxation is shown to have a negligible importance at low temperatures at which the Rabi oscillations have been detected.

  6. Investigation of Landau level spin reversal in (110) oriented p-type GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Nebile

    2009-09-01

    In this thesis, the Landau level crossing or anticrossing of hole levels has been investigated in p-type GaAs 400 Aa wide quantum wells. In magneto-transport measurements, this is evidenced with the presence of an anomalous peak in the longitudinal resistance measurements at {nu}=1. In the transversal resistance measurements, no signature of this anomalous peak is observed. By increasing the hole density in the quantum well by applying a top gate voltage, the position of the anomalous peak shifts to higher magnetic fields. At very high densities, anomalous peak disappears. By applying a back gate voltage, the electric field in the quantum well is tuned. A consequence is that the geometry of the quantum well is tuned from square to triangular. The anomalous peak position is shown to depend also on the back gate voltage applied. Temperature dependence of the peak height is consistent with thermal activation energy gap ({delta}/2= 135 {mu}eV). The activation energy gap as a function of the magnetic field has a parabolic like dependence, with the minimum of 135 {mu}eV at 4 T. The peak magnitude is observed to decrease with increasing temperature. An additional peak is observed at {nu}=2 minimum. This additional peak at {nu}=2 might be due to the higher Landau level crossing. The p-type quantum wells have been investigated by photoluminescence spectroscopy, as a function of the magnetic field. The polarization of the emitted light has been analyzed in order to distinguish between the transitions related to spin of electron {+-} 1/2 and spin of hole -+ 3/2. The transition energies of the lowest electron Landau levels with spin {+-} 1/2 and hole Landau levels with spin -+ 3/2 versus magnetic field show crossing at 4 T. The heavy hole Landau levels with spins {+-} 3/2 are obtained by the substraction of transition energies from the sum of lowest electron Landau level energy and the energy gap of GaAs. The heavy hole Landau levels show a crossing at 4 T. However, due to the

  7. Exchange coupled pairs of dangling bond spins as a new type of paramagnetic defects in nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Osipov, V. Yu., E-mail: osipov@mail.ioffe.r [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation); Faculty of Electronics, St. Petersburg State Electrotechnical University (LETI), 197376 (Russian Federation); Shames, A.I. [Department of Physics, Ben-Gurion University of the Negev, 84105 Be' er-Sheva (Israel); Vul' , A. Ya. [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation)

    2009-12-15

    EPR in detonation nanodiamonds (DND) reveals two different signals associated with intrinsic carbon inherited paramagnetic defects. Main carbon inherited EPR signal is narrow intensive Lorentzian-like singlet with g=2.0028 and spin concentration N{sub s}=(6-7)x10{sup 19} spin/g that yields on average 13-15 spins per each DND particle. Additional chemical treatment of DND powder allows practically complete removal of trace amounts of transition metal impurities that reveals a new doublet EPR signal consisting of two relatively narrow lines within the half-field region (gapprox4) separated by a distance of 10.4 mT. The intensity of the doublet signal is five orders of magnitude lower than that of the main singlet signal. The former signal has been observed in a wide variety of DND samples disregarding of the impurity level reached and thus may be attributed to some intrinsic defects in DND particles. Such half-field EPR signals correspond to 'forbidden' DELTAM{sub s}=2 transitions within thermally populated triplet (S=1) levels observed in polycrystalline samples containing exchange dimers-antiferromagnetically coupled spin pairs. Estimates suggest that the concentration of such defects is about one dimer per hundreds DND particles.

  8. Wald type analysis for spin-one fields in three dimensions

    Science.gov (United States)

    Bera, Nabarun; Das, Suchetan; Ezhuthachan, Bobby

    2017-04-01

    We revisit Wald's analysis of [5] in the context of spin-one fields in three dimensions. A key technical difference from Wald's is the role played by the three dimensional completely antisymmetric tensor. We show how this changes the analysis as well as the result from that of [5].

  9. Floating Characteristics of Rudders and Elevators in Spinning Attitudes as Determined From Hinge-Moment-Coefficient Data With Application to Personal-Owner-Type Airplanes

    National Research Council Canada - National Science Library

    Bihrle, William

    1950-01-01

    A study was made of available rudder and elevator hinge-moment-coefficient-coefficient data in order to determine the floating characteristics of various types of rudders and elevators in spinning attitudes...

  10. Sex differences and the effect of instruction on reorientation abilities by humans.

    Science.gov (United States)

    Siemens, Megan N; Kelly, Debbie M

    2017-12-27

    This study examined whether differences in the amount of information provided to men and women, in the form of verbal instruction, influenced their encoding during a reorientation task. When a navigator needs to orient, featural (e.g., colour or texture) and geometry (e.g., metric information) are used to determine which direction to begin traveling. The current study used a spatial reorientation task to examine how men and women use featural and geometric cues and whether the content of the task's instructions influenced how these cues were used. Participants were trained to find a target location in a rectangular room with distinctive objects situated at each corner. Once the participants were accurately locating the target, various tests manipulating the spatial information were conducted. We found both men and women encoded the featural cues, and even though the features provided reliable information, participants generally showed an encoding of geometry. However, when participants were not provided with any information about the spatial aspects of the task in the instructions, they failed to encode geometry. We also found that women used distant featural cues as landmarks when the featural cue closest to the target was removed, whereas men did not. Yet, when the two types of cues were placed in conflict, both sexes weighed featural cues more heavily than geometric cues. The content of the task instructions also influenced how cues were relied upon in this conflict situation. Our results have important implications for our understanding of how spatial cues are used for reorientation.

  11. Planar reorientation maneuvers of space multibody systems using internal controls

    Science.gov (United States)

    Reyhanoglu, Mahmut; Mcclamroch, N. H.

    1992-01-01

    In this paper a reorientation maneuvering strategy for an interconnection of planar rigid bodies in space is developed. It is assumed that there are no exogeneous torques, and torques generated by joint motors are used as means of control so that the total angular momentum of the multibody system is a constant, assumed to be zero in this paper. The maneuver strategy uses the nonintegrability of the expression for the angular momentum. We demonstrate that large-angle maneuvers can be designed to achieve an arbitrary reorientation of the multibody system with respect to an inertial frame. The theoretical background for carrying out the required maneuvers is briefly summarized. Specifications and computer simulations of a specific reorientation maneuver, and the corresponding control strategies, are described.

  12. Biomechanical performances of trees in the phase of active reorientation

    Directory of Open Access Journals (Sweden)

    Jana Dlouhá

    2008-01-01

    Full Text Available The purpose of the present paper was to investigate the accumulation of growth stresses in a cross section of a tree in active reorientation process and its biomechanical performances i.e. up-righting efficiency and stem flexibility. Effect of two factors was analysed in details: occurrence of juvenile wood and viscoelasticity of wood tissues. In a phase of active reorientation, wood tissues close to the pith are submitted to significant levels of compressive stresses. Production of juvenile wood in earlier stage of a tree life seems to increase the stem flexibility during active reorientation for both softwoods as well as hardwoods. Concerning the viscoelasticity of wood tissues, only minor effect has been observed in softwoods while an important positive impact has been pointed out in hardwoods. Set of simulations with increasing level of maturation strains in reaction tissues indicated possible trade-off between the stem flexibility and the up-righting efficiency.

  13. Spin model for nontrivial types of magnetic order in inverse-perovskite antiferromagnets

    Science.gov (United States)

    Mochizuki, Masahito; Kobayashi, Masaya; Okabe, Reoya; Yamamoto, Daisuke

    2018-02-01

    Nontrivial magnetic orders in the inverse-perovskite manganese nitrides are theoretically studied by constructing a classical spin model describing the magnetic anisotropy and frustrated exchange interactions inherent in specific crystal and electronic structures of these materials. With a replica-exchange Monte Carlo technique, a theoretical analysis of this model reproduces the experimentally observed triangular Γ5 g and Γ4 g spin-ordered patterns and the systematic evolution of magnetic orders. Our Rapid Communication solves a 40-year-old problem of nontrivial magnetism for the inverse-perovskite manganese nitrides and provides a firm basis for clarifying the magnetism-driven negative thermal expansion phenomenon discovered in this class of materials.

  14. Voltage-driven beam bistability in a reorientational uniaxial dielectric

    Directory of Open Access Journals (Sweden)

    Armando Piccardi

    2016-04-01

    Full Text Available We report on voltage controlled bistability of optical beams propagating in a nonlocal reorientational uniaxial dielectric, namely, nematic liquid crystals. In the nonlinear regime where spatial solitons can be generated, two stable states are accessible to a beam of given power in a finite interval of applied voltages, one state corresponding to linear diffraction and the other to self-confinement. We observe such a first-order transition and the associated hysteresis in a configuration when both the beam and the voltage reorientate the molecules beyond a threshold.

  15. Reorientation of scroll rings in an advective field

    Science.gov (United States)

    Luengviriya, Chaiya; Müller, Stefan C.; Hauser, Marcus J. B.

    2008-01-01

    When scroll rings in the excitable Belousov-Zhabotinsky reaction are subjected to an applied electrical current, a reorientation of the scroll ring is induced which is accompanied by a linear drift towards the cathode. The findings can be explained using a modified theory of local filament dynamics under parameter gradients. Numerical simulations using the Oregonator model with an additional advective term accounting for the applied electric field reproduce the experimental results and provide insights into the deformation of the structure of the filament during the reorientation.

  16. Spin Seebeck effect in Y-type hexagonal ferrite thin films

    Czech Academy of Sciences Publication Activity Database

    Hirschner, Jan; Maryško, Miroslav; Hejtmánek, Jiří; Uhrecký, Róbert; Soroka, Miroslav; Buršík, Josef; Anadón, P.; Aguirre, M.H.; Knížek, Karel

    2017-01-01

    Roč. 96, č. 6 (2017), s. 1-8, č. článku 064428. ISSN 2469-9950 R&D Projects: GA ČR(CZ) GA14-18392S Institutional support: RVO:68378271 ; RVO:61388980 Keywords : hexagonal ferrites * spin Seebeck effect * thin films * magnetization * ferrimagnetic ferrites Subject RIV: BM - Solid Matter Physics ; Magnetism; CA - Inorganic Chemistry (UACH-T) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Inorganic and nuclear chemistry (UACH-T) Impact factor: 3.836, year: 2016

  17. Language and Spatial Reorientation: Evidence from Severe Aphasia

    Science.gov (United States)

    Bek, Judith; Blades, Mark; Siegal, Michael; Varley, Rosemary

    2010-01-01

    Investigating spatial cognition in individuals with acquired language impairments can inform our understanding of how components of language are involved in spatial representation. Using the reorientation paradigm of Hermer-Vazquez, Spelke, and Katsnelson (1999), we examined spatial cue integration (landmark-geometry conjunctions) in individuals…

  18. Stategic reorientation of industrial R&D towards commercial objectives.

    NARCIS (Netherlands)

    Brook, Jacques W.; de Bruijn, E.J.; McDonough III, Edward F.; Kaynak, E.; Harcar, T.D.

    2007-01-01

    In an effort to leverage R&D knowledge asset and to create more value from industrial R&D in today’s increasing liberalized and globalising business environments, some corporations adopt a strategic reorientation of their industrial R&D organisation towards commercial objectives. This study suggests

  19. Reorientation of lineation in the Central Crystalline Zone, Munsiari ...

    Indian Academy of Sciences (India)

    During large scale ductile shear deformation, linear features of the rocks tend to be reoriented towards the direction of bulk shear. This is demonstrated in a crustal scale shear zone of the Himalaya, the. Main Central Thrust (MCT), typically exposed in the Munsiari–Milam area of eastern Kumaun Greater. Himalaya.

  20. Educating Academic Staff to Reorient Curricula in ESD

    Science.gov (United States)

    Biasutti, Michele; Makrakis, Vassilios; Concina, Eleonora; Frate, Sara

    2018-01-01

    Purpose: The purpose of this paper is to present a professional development experience for higher education academic staff within the framework of an international Tempus project focused on reorienting university curricula to address sustainability. The project included revising curricula to phase sustainable development principles into university…

  1. Spin to Charge Conversion at Room Temperature by Spin Pumping into a New Type of Topological Insulator: α-Sn Films.

    Science.gov (United States)

    Rojas-Sánchez, J-C; Oyarzún, S; Fu, Y; Marty, A; Vergnaud, C; Gambarelli, S; Vila, L; Jamet, M; Ohtsubo, Y; Taleb-Ibrahimi, A; Le Fèvre, P; Bertran, F; Reyren, N; George, J-M; Fert, A

    2016-03-04

    We present results on spin to charge current conversion in experiments of resonant spin pumping into the Dirac cone with helical spin polarization of the elemental topological insulator (TI) α-Sn. By angle-resolved photoelectron spectroscopy (ARPES), we first check that the Dirac cone (DC) at the α-Sn (0 0 1) surface subsists after covering Sn with Ag. Then we show that resonant spin pumping at room temperature from Fe through Ag into α-Sn layers induces a lateral charge current that can be ascribed to the inverse Edelstein effect by the DC states. Our observation of an inverse Edelstein effect length much longer than those generally found for Rashba interfaces demonstrates the potential of TIs for the conversion between spin and charge in spintronic devices. By comparing our results with data on the relaxation time of TI free surface states from time-resolved ARPES, we can anticipate the ultimate potential of the TI for spin to charge conversion and the conditions to reach it.

  2. Formation and partial melting of two types of spin-cluster glass behavior in vanadate spinel

    International Nuclear Information System (INIS)

    Huang Yuanjie; Pi Li; Tan Shun; Zhang Yuheng; Yang Zhaorong

    2012-01-01

    We report the doping effect on the various properties of spinels Co 1-x Zn x V 2 O 4 (0 ≤ x ≤ 0.2). For the parent compounds, the rise in magnetization, the valley in thermal conductance, the transition from the ferromagnetic arrangement to non-collinear alignment indicated by the specific heat for the V sublattice, especially the frequency dependence of AC susceptibility around T 1 = 59 K, verify the occurrence of the transition at T 1 besides the ferrimagnetic transition at T C . The ferrimagnetic transition at T C induces the spin-cluster glass behavior and the transition at T 1 yields the new spin-cluster glass (NSCG) behavior. As the Zn 2+ -doped content increases, the above phenomena are gradually weakening to vanishing, but the glassy behavior at T C still exists for all samples. Through the fourth-order perturbation theory, we discuss the reasons for the gradual vanishing of the transition at T 1 . (paper)

  3. Spinning worlds

    NARCIS (Netherlands)

    Schwarz, H.

    2017-01-01

    The thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants, with orbital periods as long as thousands of years. The thesis is based on near-infrared observations of 1

  4. Reorientation and Swimming Stability in Sea Urchin Larvae

    Science.gov (United States)

    Wheeler, J.; Chan, K. Y. K.; Anderson, E.; Helfrich, K. R.; Mullineaux, L. S.; Sengupta, A.; Stocker, R.

    2016-02-01

    Many benthic marine invertebrates have two-phase life histories, relying on planktonic larval stages for dispersal and exchange of individuals between adult populations. The dispersal of planktonic larvae is determined by two factors: passive advection by the ambient flow and active motility. By modifying dispersal and ultimately settlement, larval motility influences where and when individuals recruit into benthic communities. Despite its ecological relevance, our understanding of larval motility and behavior in the plankton remains limited, especially regarding the interactions of larval motility and ambient turbulence. As most larvae are smaller than the Kolmogorov scale, they experience ocean turbulence in part as a time-changing viscous torque produced by local fluid shear. This torque causes larval reorientation, impacting swimming direction and potentially dispersal at the macroscale. It is therefore paramount to understand the mechanisms of larval reorientation and the stability of larvae against reorientation. Here we report on the larval reorientation behavior of the sea urchins Arbacia punctulata and Heliocidaris crassispina. Both species have life histories characterized by ontogenetic changes to internal density structure and morphology, which we hypothesized to impact stability. To test this hypothesis, we performed "flip chamber" experiments, in which larvae swim freely in a small chamber that is intermittently inverted, mimicking the overturning experienced by larvae in turbulence. We investigated the role of larval age, body size, species, morphology (number of arms), and motility (live versus dead) on the reorientation dynamics. Our work contributes to a more mechanistic understanding of the role of hydrodynamics in the motility and transport of planktonic larvae.

  5. An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide.

    Science.gov (United States)

    Istomin, S Ya; Tyablikov, O A; Kazakov, S M; Antipov, E V; Kurbakov, A I; Tsirlin, A A; Hollmann, N; Chin, Y Y; Lin, H-J; Chen, C T; Tanaka, A; Tjeng, L H; Hu, Z

    2015-06-21

    The crystal and magnetic structures of brownmillerite-like Sr(2)Co(1.2)Ga(0.8)O(5) with a stable Co(3+) oxidation state at both octahedral and tetrahedral sites are refined using neutron powder diffraction data collected at 2 K (S.G. Icmm, a = 5.6148(6) Å, b = 15.702(2) Å, c = 5.4543(6) Å; R(wp) = 0.0339, R(p) = 0.0443, χ(2) = 0.775). The very large tetragonal distortion of CoO(6) octahedra (1.9591(4) Å for Co-O(eq) and 2.257(6) Å for Co-O(ax)) could be beneficial for the stabilization of the long-sought intermediate-spin state of Co(3+) in perovskite-type oxides. However, the large magnetic moment of octahedral Co(3+) (3.82(7)μ(B)) indicates the conventional high-spin state of Co(3+) ions, which is further supported by the results of a combined theoretical and experimental soft X-ray absorption spectroscopy study at the Co-L(2,3) edges on Sr(2)Co(1.2)Ga(0.8)O(5). A high-spin ground state of Co(3+) in Sr(2)Co(1.2)Ga(0.8)O(5) resulted in much lower in comparison with a LaCoO(3) linear thermal expansion coefficient of 13.1 ppm K(-1) (298-1073 K) determined from high-temperature X-ray powder diffraction data collected in air.

  6. Study on spin and charge fluctuations in {tau} -type organic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Hirohito [Institute of Physics, Kanagawa University, Yokohama 221-8686 (Japan); Kuroki, Kazuhiko [Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan)

    2012-05-15

    We theoretically study the possibility of the ferromagnetic behavior in a quasi-two-dimensional organic conductor, {tau} -(EDO-S,S -DMEDT-TTF){sub 2}(AuBr{sub 2}){sub 1+y} with y {approx} 0.875. We adopt a two-band extended Hubbard model, whose band dispersion nicely reproduces the ab initio band structure. We consider both on-site and nearest neighbor off-site repulsive interactions. By applying the random phase approximation, we find that both spin and charge susceptibilities are maximized at Q = (0, 0). Although this can be an indication of pure antiferromagnetism since two sites are present in a unit cell, the divergence of the susceptibilities at the origin of the k -space can also be related to the ferromagnetic behavior observed in this organic conductor. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Spin transition of ferric iron in the calcium-ferrite type aluminous phase: Fe 3+ Spin Transition in the CF Phase

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ye [School of Science, Wuhan University of Technology, Wuhan China; Qin, Fei [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, and School of Earth and Space Sciences, Peking University, Beijing China; Wu, Xiang [State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan China; Huang, Haijun [School of Science, Wuhan University of Technology, Wuhan China; McCammon, Catherine A. [Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth Germany; Yoshino, Takashi [Institute for Planetary Materials, Okayama University, Misasa Japan; Zhai, Shuangmeng [Key Laboratory of High-temperature and High-pressure Study of the Earth' s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang China; Xiao, Yuming [HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne Illinois USA; Prakapenka, Vitali B. [GeoSoilEnviroCARS, University of Chicago, Chicago Illinois USA

    2017-08-01

    We investigated Fe-free and Fe-bearing CF phases using nuclear forward scattering and X-ray diffraction coupled with diamond anvil cells up to 80 GPa at room temperature. Octahedral Fe3+ ions in the Fe-bearing CF phase undergo a high-spin to low-spin transition at 25–35 GPa, accompanied by a volume reduction of ~2.0% and a softening of bulk sound velocity up to 17.6%. Based on the results of this study and our previous studies, both the NAL and CF phases, which account for 10–30 vol % of subducted MORB in the lower mantle, are predicted to undergo a spin transition of octahedral Fe3+ at lower mantle pressures. Spin transitions in these two aluminous phases result in an increase of density of 0.24% and a pronounced softening of bulk sound velocity up to 2.3% for subducted MORB at 25–60 GPa and 300 K. The anomalous elasticity region expands and moves to 30–75 GPa at 1200 K and the maximum of the VΦ reduction decreases to ~1.8%. This anomalous elastic behavior of Fe-bearing aluminous phases across spin transition zones may be relevant in understanding the observed seismic signatures in the lower mantle.

  8. HfMnSb{sub 2}: a metal-ordered NiAs-type pnictide with a conical spin order

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Taito; Yamamoto, Takafumi; Tassel, Cedric; Takatsu, Hiroshi; Ajiro, Yoshitami; Kageyama, Hiroshi [Graduate School of Engineering, Kyoto University, Kyoto, 615-8510 (Japan); Ritter, Clemens [Institut Laue-Langevin, 6, rue Jules Horowitz, Grenoble, 38000 (France)

    2016-08-16

    The NiAs-type structure is one of the most common structures in solids, but metal order has been almost exclusively limited to chalcogenides. The synthesis of HfMnSb{sub 2} is reported with a novel metal-ordered NiAs-type structure. HfMnSb{sub 2} undergoes a conical spin order below 270 K, in marked contrast to conventional magnetic order observed in NiAs-type pnictides. We argue that the layered arrangement of Hf and Mn makes it a quasi 2D magnet, where the Mn layers with localized magnetic moments (Mn{sup 2+}; S=5/2) can interact only through RKKY interactions, instead of metal-metal bonding that is otherwise dominant for typical NiAs-type pnictides. This result suggests that controlling order-disorder in NiAs-type pnictides enables a study of 2D-to-3D crossover behavior in itinerant magnetic system. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. ORNL Interim Progress Report on Hydride Reorientation CIRFT Tests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yan, Yong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-28

    A systematic study of H. B. Robinson (HBR) high burnup spent nuclear fuel (SNF) vibration integrity was performed in Phase I project under simulated transportation environments, using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) hot cell testing technology developed at Oak Ridge National Laboratory in 2013–14. The data analysis on the as-irradiated HBR SNF rods demonstrated that the load amplitude is the dominant factor that controls the fatigue life of bending rods. However, previous studies have shown that the hydrogen content and hydride morphology has an important effect on zirconium alloy mechanical properties. To address the effect of radial hydrides in SNF rods, in Phase II a test procedure was developed to simulate the effects of elevated temperatures, pressures, and stresses during transfer-drying operations. Pressurized and sealed fuel segments were heated to the target temperature for a preset hold time and slow-cooled at a controlled rate. The procedure was applied to both non-irradiated/prehydrided and high-burnup Zircaloy-4 fueled cladding segments using the Nuclear Regulatory Commission-recommended 400°C maximum temperature limit at various cooling rates. Before testing high-burnup cladding, four out-of-cell tests were conducted to optimize the hydride reorientation (R) test condition with pre-hydride Zircaloy-4 cladding, which has the same geometry as the high burnup fuel samples. Test HR-HBR#1 was conducted at the maximum hoop stress of 145 MPa, at a 400°C maximum temperature and a 5°C/h cooling rate. On the other hand, thermal cycling was performed for tests HR-HBR#2, HR-HBR#3, and HR-HBR#4 to generate more radial hydrides. It is clear that thermal cycling increases the ratio of the radial hydride to circumferential hydrides. The internal pressure also has a significant effect on the radial hydride morphology. This report describes a procedure and experimental results of the four out-of-cell hydride reorientation tests of

  10. Effect of silver nanoparticles on photo-induced reorientation of azo groups in polymer films

    International Nuclear Information System (INIS)

    Zhou Jingli; Yang Jianjun; Sun Youyi; Zhang Douguo; Shen Jing; Zhang Qijin; Wang Keyi

    2007-01-01

    A series of polymer films containing azo groups and silver nanoparticles were prepared. Photo-induced reorientation of the film was conducted under irradiation of polarized light with wavelength at 365 nm, 442 nm and 532 nm, respectively. The influence of the concentration of dopant silver on the reorientation of the azo groups was studied. An enhancement of about 50% for the reorientation rate and about 70% for the reorientation amplitude was achieved. From a comparison of the enhancement obtained by irradiating with three different light sources, it was realized that the mechanism for enhancement of reorientation of azo groups is due to plasmon resonance of silver nanoparticles doped in the polymer films

  11. Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

    International Nuclear Information System (INIS)

    Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeda, T.

    2005-01-01

    We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does include only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed

  12. Comparison effects and electron spin resonance studies of α-Fe2O4 spinel type ferrite nanoparticles.

    Science.gov (United States)

    Bayrakdar, H; Yalçın, O; Cengiz, U; Özüm, S; Anigi, E; Topel, O

    2014-11-11

    α-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of α-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different α-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for α-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Forced convection in nanoparticles doped nematics without reorientation

    International Nuclear Information System (INIS)

    Hakobyan, M.R.; Hakobyan, R.S.

    2016-01-01

    The problem of forced convection in the cell of nanoparticles doped nematic liquid crystal with both boundaries being free, plane and isotherm is discussed. These boundary conditions (offered by Rayleigh) allow to get simple and exact solution for boundary-value problem, from which its most important peculiarities can be clearly seen. Particularly, there appears a possibility to induce convection without reorientation of liquid crystal director. It was shown that nanoparticles could have significant influence on the convection

  14. The energy barrier to reorientational motion of the trifluoromethyl group in lithium trifluoromethanesulphonate and its complex with poly(ethylene oxide): a comparison between modelling and NMR relaxation measurements

    Science.gov (United States)

    Moore, Elaine A.; Mortimer, Michael; Wigglesworth, Christopher; Williams, Martin A. K.

    1999-07-01

    Molecular modelling is used to calculate the barrier heights to reorientation for the trifluoromethyl group, CF 3, in both lithium trifluoromethanesulphonate, LiCF 3SO 3, and the crystalline complex of this salt with poly(ethylene oxide), PEO. The calculated barrier heights are compared with those determined from 19F spin-lattice relaxation studies. In the case of LiCF 3SO 3, fluorine-fluorine non-bonded interactions are shown to play a dominant role in determining the barrier height to CF 3 group reorientation and optimised Lennard-Jones parameters for this interaction are determined. In the crystalline complex, PEO 3·LiCF 3SO 3, it is suggested that CF 3 group reorientation is strongly influenced by segmental motions of the PEO chain.

  15. Erratum : Critical Properties of Spin-1 Antiferromagnetic Heisenberg Chains with Bond Alternation and Uniaxial Single-Ion-Type Anisotropy (vol 69, pg 237, 2000)

    OpenAIRE

    Chen, Wei; 飛田, 和男; Sanctuary, Bryan C.

    2008-01-01

    Original Paper :Critical Properties of Spin-1 Antiferromagnetic Heisenberg Chains with Bond Alternation and Uniaxial Single-Ion-Type AnisotropyWei Chen, Kazuo Hida and Bryan Clifford Sanctuary Journal of the Physical Society of Japan 69 (2000) pp.237-241

  16. Voltage- and Light-Controlled Spin Properties of a Two-Dimensional Hole Gas in p-Type GaAs/AlAs Resonant Tunneling Diodes

    Science.gov (United States)

    Galeti, H. V. A.; Galvão Gobato, Y.; Brasil, M. J. S. P.; Taylor, D.; Henini, M.

    2018-03-01

    We have investigated the spin properties of a two-dimensional hole gas (2DHG) formed at the contact layer of a p-type GaAs/AlAs resonant tunneling diode (RTD). We have measured the polarized-resolved photoluminescence of the RTD as a function of bias voltage, laser intensity and external magnetic field up to 15T. By tuning the voltage and the laser intensity, we are able to change the spin-splitting from the 2DHG from almost 0 meV to 5 meV and its polarization degree from - 40% to + 50% at 15T. These results are attributed to changes of the local electric field applied to the two-dimensional gas which affects the valence band and the hole Rashba spin-orbit effect.

  17. Experiences with Reorienting Teacher Education to Address Sustainability

    Directory of Open Access Journals (Sweden)

    Jana Dlouhá

    2014-11-01

    Full Text Available The 8th Biennial Meeting of the International Network of Teacher Education Institutions (INTEI associated with the UNESCO Chair on Reorienting Teacher Education to Address Sustainability was held in the Japanese town of Okayama on 14-17 November 2014. The meeting was hosted by the City of Okayama and the Japanese government. Themes discussed during the meeting focused education for sustainable development (ESD in teacher education, biodiversity education, and ESD’s contributions to a quality education etc. The overall aim was to explore the roles that the INTEI will play in the new Global Action Program on ESD (GAP.

  18. A new type of massive spin-one boson: And its relation with Maxwell equations

    International Nuclear Information System (INIS)

    Ahluwalia, D.V.

    1995-01-01

    First, the author showed that in the (1, 0) circle-plus (0, 1) representation space there exist not one but two theories for charged particles. In the Weinberg construct, the boson and its antiboson carry same relative intrinsic parity, whereas in the author's construct the relative intrinsic parities of the boson and its antiboson are opposite. These results originate from the commutativity of the operations of Charge conjugation and Parity in Weinberg's theory, and from the anti-commutativity of the operations of Charge conjugation and Parity in the author's theory. The author thus claims that he has constructed a first non-trivial quantum theory of fields for the Wigner-type particles. Second, the massless limit of both theories seems formally identical and suggests a fundamental modification of Maxwell equations. At its simplest level, the modification to Maxwell equations enters via additional boundary condition(s)

  19. Young children reorient by computing layout geometry, not by matching images of the environment.

    Science.gov (United States)

    Lee, Sang Ah; Spelke, Elizabeth S

    2011-02-01

    Disoriented animals from ants to humans reorient in accord with the shape of the surrounding surface layout: a behavioral pattern long taken as evidence for sensitivity to layout geometry. Recent computational models suggest, however, that the reorientation process may not depend on geometrical analyses but instead on the matching of brightness contours in 2D images of the environment. Here we test this suggestion by investigating young children's reorientation in enclosed environments. Children reoriented by extremely subtle geometric properties of the 3D layout: bumps and ridges that protruded only slightly off the floor, producing edges with low contrast. Moreover, children failed to reorient by prominent brightness contours in continuous layouts with no distinctive 3D structure. The findings provide evidence that geometric layout representations support children's reorientation.

  20. Arousal and attention re-orienting in autism spectrum disorders: evidence from auditory event-related potentials

    Directory of Open Access Journals (Sweden)

    Elena V Orekhova

    2014-02-01

    Full Text Available The extended phenotype of autism spectrum disorders (ASD includes a combination of arousal regulation problems, sensory modulation difficulties, and attention re-orienting deficit. A slow and inefficient re-orienting to stimuli that appear outside of the attended sensory stream is thought to be especially detrimental for social functioning. Event-related potentials (ERPs and magnetic fields (ERFs may help to reveal which processing stages underlying brain response to unattended but salient sensory event are affected in individuals with ASD. Previous research focusing on two sequential stages of the brain response - automatic detection of physical changes in auditory stream, indexed by mismatch negativity (MMN, and evaluation of stimulus novelty, indexed by P3a component, - found in individuals with ASD either increased, decreased or normal processing of deviance and novelty. The review examines these apparently conflicting results, notes gaps in previous findings, and suggests a potentially unifying hypothesis relating the dampened responses to unattended sensory events to the deficit in rapid arousal process. Specifically, ‘sensory gating’ studies focused on pre-attentive arousal consistently demonstrated that brain response to unattended and temporally novel sound in ASD is already affected at around 100 ms after stimulus onset. We hypothesize that abnormalities in nicotinic cholinergic arousal pathways, previously reported in individuals with ASD, may contribute to these ERP/ERF aberrations and result in attention re-orienting deficit. Such cholinergic dysfunction may be present in individuals with ASD early in life and can influence both sensory processing and attention re-orienting behavior. Identification of early neurophysiological biomarkers for cholinergic deficit would help to detect infants at risk who can potentially benefit from particular types of therapies or interventions.

  1. Size dependence of vortex-type spin torque oscillation in a Co2Fe0.4Mn0.6Si Heusler alloy disk

    Science.gov (United States)

    Seki, T.; Kubota, T.; Yamamoto, T.; Takanashi, K.

    2018-02-01

    This paper reports the systematic investigation of vortex-type spin torque oscillation in circular disks of highly spin-polarized Co2Fe0.4Mn0.6Si (CFMS) Heusler alloys. We fabricated the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices with various disk diameters (D) using the layer stack of CFMS/Ag3Mg/CFMS. The gyrotropic motion of the vortex core was successfully excited for the CFMS circular disks with 0.2 µm  ⩽  D  ⩽  0.3 µm. The CPP-GMR device with D  =  0.2 µm exhibited the Q factor of more than 5000 and the large output power of 0.4 nW owing to the high coherency of vortex dynamics and the high spin-polarization of CFMS. However, the Q factor was remarkably decreased as D was reduced from 0.2 µm to 0.14 µm. The comparison with the calculated resonance frequencies suggested that this degradation of the Q factor was due to the transition of the oscillation mode from the vortex mode to other modes such as the low-coherent out-of-plane precession mode. The present experimental results also suggest that there exists an adequate disk size for the enhanced Q factor of the vortex-type spin torque oscillation.

  2. Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

    KAUST Repository

    Ortiz Pauyac, Christian

    2016-06-19

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

  3. Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto.

    Science.gov (United States)

    Nimmo, F; Hamilton, D P; McKinnon, W B; Schenk, P M; Binzel, R P; Bierson, C J; Beyer, R A; Moore, J M; Stern, S A; Weaver, H A; Olkin, C B; Young, L A; Smith, K E

    2016-12-01

    The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto's tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin's present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.

  4. A new twist on old ideas: How sitting reorients crawlers

    Science.gov (United States)

    Soska, Kasey C.; Robinson, Scott R.; Adolph, Karen E.

    2014-01-01

    Traditionally, crawling and sitting are considered distinct motor behaviors with different postures and functions. Ten- to 12-month-old infants were observed in the laboratory or in their homes while being coaxed to crawl continuously over long, straight walkways (Study 1; N = 20) and during spontaneous crawling during free play (Study 2; N = 20). In every context, infants stopped crawling to sit 3-6 times per minute. Transitions from crawling to sitting frequently turned infants’ bodies away from the direction of heading; subsequent transitions back to crawling were offset by as much as 180° from the original direction of heading. Apparently, body reorientations result from the biomechanics of transitioning between crawling and sitting. Findings indicate that sustained, linear crawling is likely an epiphenomenon of how gait is studied in standard paradigms. Postural transitions between crawling and sitting are ubiquitous and can represent a functional unit of action. These transitions and the accompanying body reorientations likely have cascading effects for infants’ exploration, visual perception, and spatial cognition. PMID:25041056

  5. Nuclear reorientation in static and radio-frequency electro-magnetic fields

    International Nuclear Information System (INIS)

    Dubbers, D.

    1976-01-01

    Nuclear reorientation by external electromagnetic fields is treated using Fano's irreducible tensor formulation of the problem. Although the main purpose of this paper is the description of the effects of nuclear magnetic resonance (NMR) on an ensemble of oriented nuclei in the presence of a crystal electric field gradient (efg), the results are applicable to all types of nuclear or atomic orientation or angular correlation work. The theory is applied to a number of exemplary cases: magnetic field dependence of nuclear orientation in the presence of quadrupole interactions; sign determination in electric quadrupole coupling; line shapes of nuclear acoustic resonance (NAR) signals; quadrupole splitting and multiquantum transitions in NMR with oriented nuclei. (orig./WBU) [de

  6. Renal SPECT with 99m Tc-Dmsa. Reorientation and processing

    International Nuclear Information System (INIS)

    Rodriguez, J.L.; Perera, A.; Fraxedas, R.

    1998-01-01

    For the study of different renal affections with repercussion in the parenchyma is widely used the plane gammagraphy wit 99m Tc-Dmsa though not in the same way the SPECT technique. In general, the different inclination and orientation of the longitudinal axes of both kidneys in the patients entail aid to high variability in the detection of the different types of defects which leads to a possible mistaken diagnostic. With a view to this,it was developed in our centre a methodology for the automated reorientation of the different renal volumes obtained by SPECT and its posterior processing, obtaining as result a software with a high grade of independence from the operator. In this way, it is obtained a procedure standardization and so it let us with major rigor to realize evolutive studies of the patients. (Author)

  7. Reorientation of molecules in a Cl3P/Dirac h/NCCl2CF3 crystal according to NQR data

    International Nuclear Information System (INIS)

    Kyuntsel', I.A.; Mokeeva, V.A.; Soifer, G.B.

    1988-01-01

    The structural-dynamic inequivalence of the molecules in solid Cl 3 P/Dirac h/NCCl 2 CF 3 has been established, and their rotational mobility has been studied with the aid of the temperature dependence of the resonance frequency and of the spin-lattice relaxation time of the 35 Cl nuclei. The observed motion has been interpreted with consideration of the molecular structure as reorientation between unequal potential wells in the crystal lattice, and the corresponding activation parameters have been determined from the 35 Cl NQR data

  8. Spin current

    CERN Document Server

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

    2012-01-01

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

  9. Spin reorientation in the vicinity of the edge of ultrathin magnetic films and nanowires

    Czech Academy of Sciences Publication Activity Database

    Polyakova, T.; Kisielewski, M.; Maziewski, A.; Zablotskyy, Vitaliy A.

    2008-01-01

    Roč. 103, č. 7 (2008), 073912/1-073912/4 ISSN 0021-8979 Grant - others:NANOMAG-LAB(PL) 2004-003177; Spanish Ministry of Education and Science(ES) SAB2006-0120 Institutional research plan: CEZ:AV0Z10100520 Keywords : nanomagnets * magnetic anisotropy * magnetisation distributions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.201, year: 2008

  10. Spin reorientation in HoIG investigated by means of Faraday effect

    International Nuclear Information System (INIS)

    Balanda, M.; Niziol, S.

    1979-01-01

    Faraday rotation measurements in pulsed magnetic fields up to 160 kOe and in low dc fields are carried out for Ho 3 Fe 5 O 12 near the compensation point. Transition to the canted phase is observed and the temperature dependence of the critical field determined. From the holmium sublattice magnetization and Hsub(cr) versus. T gradient, values of the two molecular field coefficients are determined. (author)

  11. Nuclear paramagnetic spin relaxation theory. Paramagnetic spin probes in homogeneous and micro-heterogeneous solutions

    International Nuclear Information System (INIS)

    Westlund, P.O.

    1994-01-01

    Specific mechanisms of relaxation encountered in paramagnetic systems are described: the T1-NMRD curve and the paramagnetically enhanced nuclear spin relaxation (PER) are first discussed and a general theory of PER is proposed (nuclear paramagnetic spin relaxation theory, lattice operators, decomposition approximation, general expression of dipolar correlation functions for slow tumbling complexes, low-field approach). Numerically calculated NMRD curves are described (reorientation model, pseudo-rotation models, vibration models). Experimental studies are then analyzed: NMRD studies of paramagnetic species in an aqueous system, paramagnetic hydrated metal ions in poly-electrolytes and biochemical systems, lyotropic liquid crystalline phases, polymer solutions. 19 fig., 60 ref

  12. Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment

    Science.gov (United States)

    Shamirzaev, T. S.; Rautert, J.; Yakovlev, D. R.; Debus, J.; Gornov, A. Yu.; Glazov, M. M.; Ivchenko, E. L.; Bayer, M.

    2017-07-01

    The exciton spin dynamics are investigated both experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect band gap and a type-II band alignment. The magnetic field induced circular polarization of photoluminescence Pc is studied as function of the magnetic field strength and direction as well as sample temperature. The observed nonmonotonic behavior of these functions is provided by the interplay of bright and dark exciton states contributing to the emission. To interpret the experiment, we have developed a kinetic master equation model which accounts for the dynamics of the spin states in this exciton quartet, radiative and nonradiative recombination processes, and redistribution of excitons between these states as result of spin relaxation. The model offers quantitative agreement with experiment and allows us to evaluate, for the studied structure, the heavy-hole g factor, gh h=+3.5 , and the spin relaxation times of electron, τs e=33 μ s , and hole, τs h=3 μ s , bound in the exciton.

  13. Electrical tuning of the band alignment and magnetoconductance in an n-type ferromagnetic semiconductor (In,Fe)As-based spin-Esaki diode

    Science.gov (United States)

    Anh, Le Duc; Hai, Pham Nam; Tanaka, Masaaki

    2018-03-01

    We report a strong bias dependence of the magnetoconductance (MC) of a spin-Esaki diode composed of n+-type ferromagnetic semiconductor (FMS) (In,Fe)As and p+-type Be doped InAs grown on a p+-InAs (001) substrate by molecular beam epitaxy. When the bias voltage V is increased above 450 mV in the forward bias, we found that the MC, measured at 3.5 K under a magnetic field H of 1 T in the in-plane [110] direction, changes its sign from positive to negative and its magnitude rises rapidly from 0.5% at V fluid model, we explain both the magnitude and the anisotropy of the MC based on the evolution of the spin-Esaki diode's band profile with V. This analysis provides insights into the density of states and spin-polarization of the conduction band and the Fe-related impurity band in n-type FMS (In,Fe)As.

  14. Managerial strategies to reorient hospitals towards health promotion: lessons from organisational theory.

    Science.gov (United States)

    Röthlin, Florian

    2013-01-01

    Reorienting health services towards health promotion is one of the major health promotion strategies stipulated by the Ottawa Charter). Important contradictions, tensions and barriers to health promotion implementation associated with organisational structures have, thus far, been underexposed in the hospital health promotion discourse. This paper aims at identifying risks and the chances for hospital management to strategically and sustainably reorient their hospitals towards health promotion. The paper combines theories and findings from organisational science and management studies as well as from capacity development in the form of a narrative literature review. The aim is to focus on the conditions hospitals, as organisational systems with a highly professionalised workforce, provide for a strategically managed reorientation towards health promotion. Models and principles helping managers to navigate the difficulties and complexities of health promotion reorientation will be suggested. Hospital managers have to deal with genuine obstacles in the complexity and structural formation of hospital organisations. Against this background, continuous management support, a transformative leadership style, participative strategic management and expert governance can be considered important organisational capacities for the reorientation towards a new concept such as health promotion. This paper discusses managerial strategies, effective structural transformations and important organisational capacities that can contribute to a sustainable reorientation of hospitals towards health promotion. It supports hospital managers in exploring their chances of facilitating and effectively supporting a sustainable health promotion reorientation of their hospitals. The paper provides an innovative approach where the focus is on enhanced possibilities for hospital managers to strategically manage the reorientation towards health promotion.

  15. A magnetic relaxation study on anisotropic reorientation in aqueous polyelectrolyte solutions

    International Nuclear Information System (INIS)

    Mulder, C.W.R.

    1984-01-01

    The present thesis proposes a study on anisotropic reorientation of aqueous polyelectrolyte solutions. In particular, it is directed to the question to what extent information may be obtained on anisotropic reorientation by nuclear magnetic relaxation experiments. The polymethacrylic acid/water system has been chosen as probe system. (Auth.)

  16. The reorientation of spatial planning systems and policies

    DEFF Research Database (Denmark)

    Galland, Daniel; Enemark, Stig

    2012-01-01

    the implementation of a structural reform that changed the political and administrative structure in the country. Most importantly, the reform abolished the county level, which caused that planning policies, functions and responsibilities were re-scaled to municipal and national levels. This situation brought about......Danish spatial planning has been increasingly subjected to profound reorientations over the past two decades. The comprehensive frame wherein planning policies and practices operated across different levels of administration has become significantly altered. This has been particularly evident after...... radical shifts in terms of the scope of planning policies, the implementation of land-use tasks as well as the performance of the institutional arrangements operating within and beyond the planning system. Based on an in-depth analysis concerned with these changes, the paper endeavours into discussing how...

  17. Understanding the reorientations and roles of spatial planning

    DEFF Research Database (Denmark)

    Galland, Daniel

    2012-01-01

    Spatial planning commonly adopts a diversity of functions and logics in contributing to handle growth and development. Being influenced by an array of contextual driving forces that result in specific institutional practices and policy agendas, spatial planning seems to be constantly reoriented...... in terms of its purposes and reasoning. This article sets out to explore the diverse orientations and roles that spatial planning has assumed in Denmark over a 50-year period. In doing so, the article examines the evolution of national planning policy by means of a multi-disciplinary framework comprised...... by analytical concepts drawn from planning theory, state spatial theory and discourse analysis. Based on an in-depth study, the article then attempts to qualify, illustrate and synthesise the diverse roles that spatial planning has taken in Denmark throughout that time frame. The article concludes that spatial...

  18. Tidal reorientation and the fracturing of Jupiter's moon Europa

    Science.gov (United States)

    McEwen, A.S.

    1986-01-01

    The most striking characteristic of Europa is the network of long linear albedo markings over the surface, suggestive of global-scale tectonic processes. Various explanations for the fractures have been proposed: Freezing and expansion of an early liquid water ocean1, planetary expansion due to dehydration of hydrated silicates2, localization by weak points in the crust generated by impacts3, and a combination of stresses due to planetary volume change and tidal distortions from orbital recession and orbital eccentricity4,5. Calculations by Yoder6 and Greenberg and Weidenschilling7 have shown that Europa may rotate slightly more rapidly than the synchronous rate, with a rotation period (reorientation through 360??) ranging from 20 to >103 yr if a liquid mantle is present, or up to 1010 yr if the satellite is essentially solid7. Helfen-stein and Parmentier8 modelled the stresses due to nonsynchronous rotation, and concluded that this could explain the long fractures in part of the anti-jovian hemisphere. In this note, I present a global map of lineaments with long arc lengths (>20?? or 550 km), and compare the lineament orientations to the tensile stress trajectories due to tidal distortions (changes in the lengths of three principal semiaxes) and to nonsynchronous rotation (longitudinal reorientation of two of the principal semiaxes). An excellent orthogonal fit to the lineaments is achieved by the stresses due to nonsynchronous rotation with the axis radial to Jupiter located 25?? east of its present position. This fit suggests that nonsynchronous rotation occurred at some time in Europa's history. ?? 1986 Nature Publishing Group.

  19. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Spin tunnelling; spin path integrals; discrete phase integral method; diabolical points. ... technologies. Our purpose in this article is rather different. The molecular systems have total spin of the order of 10, and magnetocrystalline anisotropies of few tens of Kelvin ...... The point С' is of this new type, and here it may be said to.

  20. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    tunnel junctions were introduced as memory elements in new types of non-volatile magnetic memories (MRAM). A first 4Mbit product was launched by Freescale in July 2006. Future generations of memories are being developed by academic groups or companies. the combination of magnetic elements with CMOS components opens a whole new paradigm in hybrid electronic components which can change the common conception of the architecture of complex electronic components with a much tighter integration of logic and memory. the steady magnetic excitations stimulated by spin-transfer might be used in a variety of microwave components provided the output power can be increased. Intense research and development efforts are being aimed at increasing this power by the synchronization of oscillators. The articles compiled in this special issue of Journal of Physics: Condensed Matter, devoted to spin electronics, review these recent developments. All the contributors are greatly acknowledged.

  1. Time course and auxin sensitivity of cortical microtubule reorientation in maize roots

    Science.gov (United States)

    Blancaflor, E. B.; Hasenstein, K. H.

    1995-01-01

    The kinetics of MT [microtubule] reorientation in primary roots of Zea mays cv. Merit, were examined 15, 30, 45, and 60 min after horizontal positioning. Confocal microscopy of longitudinal tissue sections showed no change in MT orientation 15 and 30 min after horizontal placement. However, after 45 and 60 min, MTs of the outer 4-5 cortical cell layers along the lower side were reoriented. In order to test whether MT reorientation during graviresponse is caused by an auxin gradient, we examined the organization of MTs in roots that were incubated for 1 h in solutions containing 10(-9) to 10(-6) M IAA. IAA treatment at 10(-8) M or less showed no major or consistent changes but 10(-7) M IAA resulted in MT reorientation in the cortex. The auxin effect does not appear to be acid-induced since benzoic acid (10(-5) M) did not cause MT reorientation. The region closest to the maturation zone was most sensitive to IAA. The data indicate that early stages of gravity induced curvature occur in the absence of MT reorientation but sustained curvature leads to reoriented MTs in the outer cortex. Growth inhibition along the lower side of graviresponding roots appears to result from asymmetric distribution of auxin following gravistimulation.

  2. Polar phonons and spin excitations coupling in multiferroic BiFeO3 crystals

    OpenAIRE

    Rovillain, P.; Cazayous, M.; Gallais, Y.; Sacuto, A.; Lobo, R. P. S. M.; Lebeugle, D.; Colson, D.

    2009-01-01

    Raman scattering measurements on BiFeO3 single crystals show an important coupling between the magnetic order and lattice vibrations. The temperature evolution of phonons shows that the lowest energy E and A1 phonon modes are coupled to the spin order up to the Neel temperature. Furthermore, low temperature anomalies associated with the spin re-orientation are observed simultaneously in both the E phonon and the magnon. These results suggest that magnetostriction plays an important role in Bi...

  3. Engineered spin-valve type magnetoresistance in Fe$_3$O$_4$-CoFe$_2$O$_4$ core-shell nanoparticles

    OpenAIRE

    Kumar, P. Anil; Ray, Sugata; Chakraverty, S.; Sarma, D. D.

    2013-01-01

    Naturally occurring spin-valve-type magnetoresistance (SVMR), recently observed in Sr2FeMoO6 samples, suggests the possibility of decoupling the maximal resistance from the coercivity of the sample. Here we present the evidence that SVMR can be engineered in specifically designed and fabricated core-shell nanoparticle systems, realized here in terms of soft magnetic Fe3O4 as the core and hard magnetic insulator CoFe2O4 as the shell materials. We show that this provides a magnetically switchab...

  4. Switching of bacterial adhesion to a glycosylated surface by reversible reorientation of the carbohydrate ligand

    DEFF Research Database (Denmark)

    Weber, Theresa; Chrasekaran, Vijayan; Stamer, Insa

    2014-01-01

    The surface recognition in many biological systems is guided by the interaction of carbohydrate-specific proteins (lectins) with carbohydrate epitopes (ligands) located within the unordered glycoconjugate layer (glycocalyx) of cells. Thus, for recognition, the respective ligand has to reorient...

  5. Drawing the straight line : social movements and hierarchies of evidence in sexual reorientation therapy debates

    OpenAIRE

    Waidzunas, Thomas John

    2010-01-01

    This dissertation examines the construction of scientific knowledge about "sexual orientation," as it has emerged within debates over reorientation therapies in the United States from the 1950s to the present. Experts struggling over reorientation in this context have been preoccupied with the sexualities of white men, and consequently, have constructed sexual subjectivities intertwined with particular notions of white American masculinity. Drawing on science studies, sexuality studies, and s...

  6. Measurement of vortex motion in a type-II superconductor: A novel use of the neutron spin-echo technique

    Science.gov (United States)

    Forgan; Kealey; Johnson; Pautrat; Simon; Lee; Aegerter; Cubitt; Farago; Schleger

    2000-10-16

    We have used the neutron spin-echo technique to measure the small energy change of neutrons which are diffracted by a moving vortex lattice in a low-pinning Nb-Ta superconducting sample. A transport current was passed in the mixed state to cause flux line movement. In the case of uniform motion, the flux velocity v(L) was given as expected by the values of electric and magnetic fields, via E = -v(L)wedgeB. We show that with a nonuniformly moving vortex lattice, one can measure the dispersion of the velocities, opening up new possibilities for investigating moving vortex lines.

  7. Reorienting land degradation towards sustainable land management: linking sustainable livelihoods with ecosystem services in rangeland systems.

    Science.gov (United States)

    Reed, M S; Stringer, L C; Dougill, A J; Perkins, J S; Atlhopheng, J R; Mulale, K; Favretto, N

    2015-03-15

    This paper identifies new ways of moving from land degradation towards sustainable land management through the development of economic mechanisms. It identifies new mechanisms to tackle land degradation based on retaining critical levels of natural capital whilst basing livelihoods on a wider range of ecosystem services. This is achieved through a case study analysis of the Kalahari rangelands in southwest Botswana. The paper first describes the socio-economic and ecological characteristics of the Kalahari rangelands and the types of land degradation taking place. It then focuses on bush encroachment as a way of exploring new economic instruments (e.g. Payments for Ecosystem Services) designed to enhance the flow of ecosystem services that support livelihoods in rangeland systems. It does this by evaluating the likely impacts of bush encroachment, one of the key forms of rangeland degradation, on a range of ecosystem services in three land tenure types (private fenced ranches, communal grazing areas and Wildlife Management Areas), before considering options for more sustainable land management in these systems. We argue that with adequate policy support, economic mechanisms could help reorient degraded rangelands towards more sustainable land management. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. A Role for Attentional Reorienting During Approximate Multiplication and Division

    Directory of Open Access Journals (Sweden)

    Curren Katz

    2017-12-01

    Full Text Available When asked to estimate the outcome of arithmetic problems, participants overestimate for addition problems and underestimate for subtraction problems, both in symbolic and non-symbolic format. This bias is referred to as operational momentum effect (OM. The attentional shifts account holds that during computation of the outcome participants are propelled too far along a spatial number representation. OM was observed in non-symbolic multiplication and division while being absent in symbolic multiplication and division. Here, we investigate whether (a the absence of the OM in symbolic multiplication and division was due to the presentation of the correct outcome amongst the response alternatives, putatively triggering verbally mediated fact retrieval, and whether (b OM is correlated with attentional parameters, as stipulated by the attentional account. Participants were presented with symbolic and non-symbolic multiplication and division problems. Among seven incorrect response alternatives participants selected the most plausible result. Participants were also presented with a Posner task, with valid (70%, invalid (15% and neutral (15% cues pointing to the position at which a subsequent target would appear. While no OM was observed in symbolic format, non-symbolic problems were subject to OM. The non-symbolic OM was positively correlated with reorienting after invalid cues. These results provide further evidence for a functional association between spatial attention and approximate arithmetic, as stipulated by the attentional shifts account of OM. They also suggest that the cognitive processes underlying multiplication and division are less prone to spatial biases compared to addition and subtraction, further underlining the involvement of differential cognitive processes.

  9. Spin current

    CERN Document Server

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

    2017-01-01

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

  10. Guest Induced Strong Cooperative One- and Two-Step Spin Transitions in Highly Porous Iron(II) Hofmann-Type Metal-Organic Frameworks.

    Science.gov (United States)

    Piñeiro-López, Lucı A; Valverde-Muñoz, Francisco Javier; Seredyuk, Maksym; Muñoz, M Carmen; Haukka, Matti; Real, José Antonio

    2017-06-19

    The synthesis, crystal structure, magnetic, calorimetric, and Mössbauer studies of a series of new Hofmann-type spin crossover (SCO) metal-organic frameworks (MOFs) is reported. The new SCO-MOFs arise from self-assembly of Fe II , bis(4-pyridyl)butadiyne (bpb), and [Ag(CN) 2 ] - or [M II (CN) 4 ] 2- (M II = Ni, Pd). Interpenetration of four identical 3D networks with α-Po topology are obtained for {Fe(bpb)[Ag I (CN) 2 ] 2 } due to the length of the rod-like bismonodentate bpb and [Ag(CN) 2 ] - ligands. The four networks are tightly packed and organized in two subsets orthogonally interpenetrated, while the networks in each subset display parallel interpenetration. This nonporous material undergoes a very incomplete SCO, which is rationalized from its intricate structure. In contrast, the single network Hofmann-type MOFs {Fe(bpb)[M II (CN) 4 ]}·nGuest (M II = Ni, Pd) feature enhanced porosity and display complete one-step or two-step cooperative SCO behaviors when the pores are filled with two molecules of nitrobenzene or naphthalene that interact strongly with the pyridyl and cyano moieties of the bpb ligands via π-π stacking. The lack of these guest molecules favors stabilization of the high-spin state in the whole range of temperatures. However, application of hydrostatic pressure induces one- and two-step SCO.

  11. Spin Electronics

    Science.gov (United States)

    2003-08-01

    applications, a ferromagnetic metal may be used as a source of spin-polarized electronics to be injected into a semiconductor, a superconductor or a...physical phenomena in II-VI and III-V semiconductors. In II-VI systems, the Mn2+ ions act to boost the electron spin precession up to terahertz ...conductors, proximity effect between ferromagnets and superconductors , and the effects of spin injection on the physical properties of the

  12. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  13. Hardy's argument and successive spin-s measurements

    International Nuclear Information System (INIS)

    Ahanj, Ali

    2010-01-01

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

  14. The relationship between reorientational molecular motions and phase transitions in [Mg(H{sub 2}O){sub 6}](BF{sub 4}){sub 2}, studied with the use of {sup 1}H and {sup 19}F NMR and FT-MIR

    Energy Technology Data Exchange (ETDEWEB)

    Mikuli, Edward, E-mail: mikuli@chemia.uj.edu.pl; Hetmańczyk, Joanna [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Grad, Bartłomiej [Department of Forest Pathology, Faculty of Forestry, Agricultural University of Cracow, Aleja 29 listopada 46, 31-425 Kraków (Poland); Kozak, Asja; Wąsicki, Jan W.; Bilski, Paweł; Hołderna-Natkaniec, Krystyna [Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Medycki, Wojciech [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań (Poland)

    2015-02-14

    A {sup 1}H and {sup 19}F nuclear magnetic resonance study of [Mg(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} has confirmed the existence of two phase transitions at T{sub c1} ≈ 257 K and T{sub c2} ≈ 142 K, detected earlier by the DSC method. These transitions were reflected by changes in the temperature dependences of both proton and fluorine of second moments M{sub 2}{sup H} and M{sub 2}{sup F} and of spin-lattice relaxation times T{sub 1}{sup H} and T{sub 1}{sup F}. The study revealed anisotropic reorientations of whole [Mg(H{sub 2}O){sub 6}]{sup 2+} cations, reorientations by 180° jumps of H{sub 2}O ligands, and aniso- and isotropic reorientations of BF{sub 4}{sup −} anions. The activation parameters for these motions were obtained. It was found that the phase transition at T{sub c1} is associated with the reorientation of the cation as a whole unit around the C{sub 3} axis and that at T{sub c2} with isotropic reorientation of the BF{sub 4}{sup −} anions. The temperature dependence of the full width at half maximum value of the infrared band of ρ{sub t}(H{sub 2}O) mode (at ∼596 cm{sup −1}) indicated that in phases I and II, all H{sub 2}O ligands in [Mg(H{sub 2}O){sub 6}]{sup 2+} perform fast reorientational motions (180° jumps) with a mean value of activation energy equal to ca 10 kJ mole{sup −1}, what is fully consistent with NMR results. The phase transition at T{sub c1} is associated with a sudden change of speed of fast (τ{sub R} ≈ 10{sup −12} s) reorientational motions of H{sub 2}O ligands. Below T{sub c2} (in phase III), the reorientations of certain part of the H{sub 2}O ligands significantly slow down, while others continue their fast reorientation with an activation energy of ca 2 kJ mole{sup −1}. This fast reorientation cannot be evidenced in NMR relaxation experiments. Splitting of certain IR bands connected with H{sub 2}O ligands at the observed phase transitions suggests a reduction of the symmetry of the octahedral [Mg(H{sub 2}O

  15. Preparation and Adsorption Property of Imido-acetic Acid Type Chelating Nano-fibers by Electro-spinning Technique

    Science.gov (United States)

    Yang, Jiali; Lu, Lansi; Zhang, Zhu; Liao, Minhui; He, Huirong; Li, Lingxing; Chen, Jida; Chen, Shijin

    2017-12-01

    A novel nano-fibrous adsorbent from imino-acetic acid (IDA) and polyvinyl alcohol (PVA) mixture solution was prepared by electro-spinning technique. The nano-fibrous adsorbents with imino-acetic acid functional groups were characterized and demonstrated by fourier transform infrared spectrometry (FT-IR) and the scanning electron microscopy (SEM). The effect of the adsorbents to remove heavy metals such as lead (Pb) and copper (Cu) ions from the aqueous solution was studied. The maximum adsorption percentage (SP) of the metal ions can reach 93.08% for Cu (II) and 96.69% for Pb(II), respectively. Furthermore, it shows that the adsorption procedure of the adsorbents is spontaneous and endothermic, and adsorption rate fits well with pseudo-second-order kinetic model. Most importantly, the reusability of the nanofibers for removal of metal ions was also demonstrated to be used at least five times.

  16. Analysis of state-of-the-art single-thruster attitude control techniques for spinning penetrator

    Science.gov (United States)

    Raus, Robin; Gao, Yang; Wu, Yunhua; Watt, Mark

    2012-07-01

    The attitude dynamics and manoeuvre survey in this paper is performed for a mission scenario involving a penetrator-type spacecraft: an axisymmetric prolate spacecraft spinning around its minor axis of inertia performing a 90° spin axis reorientation manoeuvre. In contrast to most existing spacecraft only one attitude control thruster is available, providing a control torque perpendicular to the spin axis. Having only one attitude thruster on a spinning spacecraft could be preferred for spacecraft simplicity (lower mass, lower power consumption etc.), or it could be imposed in the context of redundancy/contingency operations. This constraint does yield restrictions on the thruster timings, depending on the ratio of minor to major moments of inertia among other parameters. The Japanese Lunar-A penetrator spacecraft proposal is a good example of such a single-thruster spin-stabilised prolate spacecraft. The attitude dynamics of a spinning rigid body are first investigated analytically, then expanded for the specific case of a prolate and axisymmetric rigid body and finally a cursory exploration of non-rigid body dynamics is made. Next two well-known techniques for manoeuvring a spin-stabilised spacecraft, the Half-cone/Multiple Half-cone and the Rhumb line slew, are compared with two new techniques, the Sector-Arc Slew developed by Astrium Satellites and the Dual-cone developed at Surrey Space Centre. Each technique is introduced and characterised by means of simulation results and illustrations based on the penetrator mission scenario and a brief robustness analysis is performed against errors in moments of inertia and spin rate. Also, the relative benefits of each slew algorithm are discussed in terms of slew accuracy, energy (propellant) efficiency and time efficiency. For example, a sequence of half-cone manoeuvres (a Multi-half-cone manoeuvre) tends to be more energy-efficient than one half-cone for the same final slew angle, but more time-consuming. As another

  17. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  18. 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.

  19. Quantum spin transport in semiconductor nanostructures

    International Nuclear Information System (INIS)

    Schindler, Christoph

    2012-01-01

    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.

  20. Neutron diffraction study of the BiFeO₃ spin cycloid at low temperature.

    Science.gov (United States)

    Herrero-Albillos, Julia; Catalan, Gustau; Rodriguez-Velamazan, José Alberto; Viret, Michel; Colson, Dorothée; Scott, James F

    2010-06-30

    The reported observation of two anomalies in the intensity of the magnon Raman peaks of BiFeO₃ at 140 and 200 K (Singh et al 2008 J. Phys.: Condens. Mater 20 252203; Cazayous et al 2008 Phys. Rev. Lett. 101 037601) led to the hypothesis that such anomalies might originate from a spin reorientation transition. In order to test this hypothesis, we have used temperature-dependent neutron diffraction to track the evolution of the magnetic configuration in single crystals of BiFeO₃. Our results indicate that there is no average reorientation of the spins. This suggests that the magnon anomalies may instead be related to the freezing of modes that do not alter the average projection of the spins over the plane of the cycloid, as also reported for multiferroic TbMnO₃ (Senff et al 2006 J. Phys.: Condens. Mater 18 2069).

  1. Engineered spin-valve type magnetoresistance in Fe3O4-CoFe2O4 core-shell nanoparticles

    Science.gov (United States)

    Anil Kumar, P.; Ray, Sugata; Chakraverty, S.; Sarma, D. D.

    2013-09-01

    Naturally occurring spin-valve-type magnetoresistance (SVMR), recently observed in Sr2FeMoO6 samples, suggests the possibility of decoupling the maximal resistance from the coercivity of the sample. Here we present the evidence that SVMR can be engineered in specifically designed and fabricated core-shell nanoparticle systems, realized here in terms of soft magnetic Fe3O4 as the core and hard magnetic insulator CoFe2O4 as the shell materials. We show that this provides a magnetically switchable tunnel barrier that controls the magnetoresistance of the system, instead of the magnetic properties of the magnetic grain material, Fe3O4, and thus establishing the feasibility of engineered SVMR structures.

  2. Synthesis and characterization of Ba0.5Pb0.5TiO3 perovskite - type thin films deposited by spin coating at low temperatures

    International Nuclear Information System (INIS)

    Wermuth, T.B.; Wiederkehr, N.A.; Alves, A.K.; Bergmann, C.P.

    2014-01-01

    In this paper we present a non-aqueous sol-gel route for the obtention of solid compounds and thin films of oxide type- perovskite ABO 3 , such as Ba 0.5 Pb 0.5 TiO 3 , synthesized by sol - gel route with subsequent heat treatment. The solid compounds were characterized by X-ray diffraction (XRD) techniques and thermal analysis (TGA / DTA). The thin film was obtained by using spin-coating techniques at low temperatures onto commercial substrates of polymethylmethacrylate (PMMA) and characterized by contact angle, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that the films present microstructures and roughness directly related to annealing temperatures, characterized by the formation of crystalline nanostructures with surface regularity and transparency. (author)

  3. 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.

  4. Reorientation response of magnetic microspheres attached to gold electrodes under an applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    De Los Santos Valladares, L.; Reeve, R.M.; Mitrelias, T.; Langford, R.M.; Barnes, C.H.W., E-mail: luis_d_v@hotmail.com [Cavendish Laboratory, Department of Physics, University of Cambridge Materials and Structures Laboratory (United Kingdom); Bustamante Dominguez, A. [Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, Lima (Peru); Aguiar, J. Albino [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Fisica; Azuma, Y. [Materials and Structures Laboratory, Tokyo Institute of Technology, Midori-ku, Yokohama (Japan); Majima, Y. [CREST, Japan Science and Technology Agency (JST), Midori-ku, Yokohama (Japan)

    2013-08-15

    In this work, we report the mechanical reorientation of thiolated ferromagnetic microspheres bridging a pair of gold electrodes under an external magnetic field. When an external magnetic field (7 kG) is applied during the measurement of the current-voltage characteristics of a carboxyl ferromagnetic microsphere (4 μm diameter) attached to two gold electrodes by self-assembled monolayers (SAMs) of octane dithiol (C{sub 8}H{sub 18}S{sub 2}), the current signal is distorted. Rather than due to magnetoresistance, this effect is caused by a mechanical reorientation of the ferromagnetic sphere, which alters the number of SAMs between the sphere and the electrodes and therefore affects conduction. To study the physical reorientation of the ferromagnetic particles, we measure their hysteresis loops while suspended in a liquid solution. (author)

  5. Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field.

    Science.gov (United States)

    García-García, Amanda; Vergaz, Ricardo; Algorri, José F; Zito, Gianluigi; Cacace, Teresa; Marino, Antigone; Otón, José M; Geday, Morten A

    2016-01-01

    Single-wall carbon nanotubes (SWCNT) are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules.

  6. Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

    Directory of Open Access Journals (Sweden)

    Amanda García-García

    2016-06-01

    Full Text Available Single-wall carbon nanotubes (SWCNT are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules.

  7. 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.

  8. Inverse spin Hall effect induced by spin pumping into semiconducting ZnO

    International Nuclear Information System (INIS)

    Lee, Jung-Chuan; Huang, Leng-Wei; Hung, Dung-Shing; Chiang, Tung-Han; Huang, J. C. A.; Liang, Jun-Zhi; Lee, Shang-Fan

    2014-01-01

    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

  9. Spin electronics

    CERN Document Server

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

    2004-01-01

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

  10. Spin glasses

    International Nuclear Information System (INIS)

    Fischer, K.H.; Hertz, J.A.

    1993-01-01

    Spin glasses, simply defined by the authors as a collection of spins (i.e., magnetic moments) whose low-temperature state is a frozen disordered one, represent one of the fascinating new fields of study in condensed matter physics, and this book is the first to offer a comprehensive account of the subject. Included are discussions of the most important developments in theory, experimental work, and computer modeling of spin glasses, all of which have taken place essentially within the last two decades. The first part of the book gives a general introduction to the basic concepts and a discussion of mean field theory, while the second half concentrates on experimental results, scaling theory, and computer simulation of the structure of spin glasses

  11. Temperature dependence of spin photocurrent spectra induced by Rashba- and Dresselhaus-type circular photogalvanic effect at inter-band excitation in InGaAs/AlGaAs quantum wells.

    Science.gov (United States)

    Yu, Jinling; Cheng, Shuying; Lai, Yunfeng; Zheng, Qiao; Zhu, Laipan; Chen, Yonghai; Ren, Jun

    2015-10-19

    Spin photocurrent spectra induced by Rashba- and Dresselhaus-type circular photogalvanic effect (CPGE) at inter-band excitation have been experimentally investigated in InGaAs/AlGaAs quantum wells at a temperature range of 80 to 290 K. It is found that, the sign of Rashba-type current reverses at low temperatures, while that of Dresselhaus-type remains unchanged. The temperature dependence of ratio of Rashba and Dresselhaus spin-orbit coupling parameters, increasing from -6.7 to 17.9, is obtained, and the possible reasons are discussed. We also develop a model to extract the Rashba-type effective electric field at different temperatures. It is demonstrated that excitonic effect will significantly influence the Rashba-type CPGE, while it has little effect on Dresselhaus-type CPGE.

  12. The gut microbiota elicits a profound metabolic reorientation in the mouse jejunal mucosa during conventionalisation.

    Science.gov (United States)

    El Aidy, Sahar; Merrifield, Claire A; Derrien, Muriel; van Baarlen, Peter; Hooiveld, Guido; Levenez, Florence; Doré, Joel; Dekker, Jan; Holmes, Elaine; Claus, Sandrine P; Reijngoud, Dirk-Jan; Kleerebezem, Michiel

    2013-09-01

    Proper interactions between the intestinal mucosa, gut microbiota and nutrient flow are required to establish homoeostasis of the host. Since the proximal part of the small intestine is the first region where these interactions occur, and since most of the nutrient absorption occurs in the jejunum, it is important to understand the dynamics of metabolic responses of the mucosa in this intestinal region. Germ-free mice aged 8-10 weeks were conventionalised with faecal microbiota, and responses of the jejunal mucosa to bacterial colonisation were followed over a 30-day time course. Combined transcriptome, histology, (1)H NMR metabonomics and microbiota phylogenetic profiling analyses were used. The jejunal mucosa showed a two-phase response to the colonising microbiota. The acute-phase response, which had already started 1 day after conventionalisation, involved repression of the cell cycle and parts of the basal metabolism. The secondary-phase response, which was consolidated during conventionalisation (days 4-30), was characterised by a metabolic shift from an oxidative energy supply to anabolic metabolism, as inferred from the tissue transcriptome and metabonome changes. Detailed transcriptome analysis identified tissue transcriptional signatures for the dynamic control of the metabolic reorientation in the jejunum. The molecular components identified in the response signatures have known roles in human metabolic disorders, including insulin sensitivity and type 2 diabetes mellitus. This study elucidates the dynamic jejunal response to the microbiota and supports a prominent role for the jejunum in metabolic control, including glucose and energy homoeostasis. The molecular signatures of this process may help to find risk markers in the declining insulin sensitivity seen in human type 2 diabetes mellitus, for instance.

  13. Non-spherical voids and lattice reorientation patterning in a shock-loaded Al single crystal

    DEFF Research Database (Denmark)

    Hong, Chuanshi; Fæster, Søren; Hansen, Niels

    2017-01-01

    An Al single crystal shock loaded in the direction and captured at incipient spallation was examined by combining X-ray tomography, electron backscatter diffraction on a scanning electron microscope, and transmission electron microscopy (TEM). Octahedral voids with {1 1 1} faces were...... of the observed reorientation patterns based on active slip systems rationalizes the key features observed and suggests that the systematic reorientation patterns result from the dominance of a single slip system in each individual zone. Microstructures revealed by TEM in the spall region show formation...

  14. Mean-field theory of photoinduced molecular reorientation in azobenzene liquid crystalline side-chain polymers

    DEFF Research Database (Denmark)

    Pedersen, T.G.; Johansen, P.M.

    1997-01-01

    . The theory provides an explanation for the high long-term stability of the photoinduced anisotropy as well as a theoretical prediction of the temporal behavior of photoinduced birefringence. The theoretical results agree favorably with measurements in the entire range of writing intensities used......A novel mean-field theory of photoinduced reorientation and optical anisotropy in liquid crystalline side-chain polymers is presented and compared with experiments, The reorientation mechanism is based on photoinduced trans cis isomerization and a multidomain model of the material is introduced...

  15. Molecular reorientation in cross polarization gratings formed in thin photoreactive-polymer-liquid-crystal films

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Hiroshi [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan)], E-mail: onoh@nagaokaut.ac.jp; Hatayama, Akira; Emoto, Akira [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan); Kawatsuki, Nobuhiro [Department of Materials Science and Chemistry, Himeji Institute of Technology, 2167 Shosha, Himeji 671-2201 (Japan)

    2008-04-30

    We present the results from some experimental and theoretical studies aimed at revealing the mechanism leading to the diffraction properties of two-dimensional cross polarization gratings in photocrosslinkable polymer liquid crystals. Although the polarization gratings are overwritten at the same place, each polarization grating works independently in our material system. The above-mentioned characteristic of our cross polarization gratings originates in the grating formation mechanism in the photocrosslinkable polymer liquid crystals, in which the molecules in the solid-state polymeric materials are not reoriented during exposure and reorientation is generated during the annealing process after multiple exposure.

  16. Effects of various grading types of gallium-ion contents on the properties of Cu(In,Ga)Se2 films prepared via the spin coating method

    Science.gov (United States)

    Wu, Chung-Hsien; Chen, Fu-Shan; Lin, Shin-Hom; Ou, Chang-Ying; Lu, Chung-Hsin

    2018-02-01

    Copper indium gallium diselenide (Cu(In,Ga)Se2) films with different gallium-ion contents were prepared via a spin coating method followed by a selenization process. Increasing the gallium-ion contents of the prepared films decreased the lattice constants and increased the band gaps. Secondary ion mass spectroscopy analysis revealed that Cu(In,Ga)Se2 films with different band gap grading types were successfully fabricated. Increasing the contents of gallium ions near the substrate resulted in an increase in the short-circuit current density. On the other hand, increasing in the contents of gallium ions near the surface of the Cu(In,Ga)Se2 films significantly increased open-circuit voltage V oc. By combining a normal and a reverse grading of gallium-ion contents, Cu(In,Ga)Se2 films with double grading types of gallium-ions contents exhibited superior electrical properties. The conversion efficiency and fill factor of solar cells with a double grading type of gallium-ion contents reached 6% and 58.7%, respectively.

  17. Spin Currents and Spin Orbit Torques in Ferromagnets and Antiferromagnets

    Science.gov (United States)

    Hung, Yu-Ming

    This thesis focuses on the interactions of spin currents and materials with magnetic order, e.g., ferromagnetic and antiferromagnetic thin films. The spin current is generated in two ways. First by spin-polarized conduction-electrons associated with the spin Hall effect in heavy metals (HMs) and, second, by exciting spin-waves in ferrimagnetic insulators using a microwave frequency magnetic field. A conduction-electron spin current can be generated by spin-orbit coupling in a heavy non-magnetic metal and transfer its spin angular momentum to a ferromagnet, providing a means of reversing the magnetization of perpendicularly magnetized ultrathin films with currents that flow in the plane of the layers. The torques on the magnetization are known as spin-orbit torques (SOT). In the first part of my thesis project I investigated and contrasted the quasistatic (slowly swept current) and pulsed current-induced switching characteristics of micrometer scale Hall crosses consisting of very thin (thesis project studies and considers applications of SOT-driven domain wall (DW) motion in a perpendicularly magnetized ultrathin ferromagnet sandwiched between a heavy metal and an oxide. My experiment results demonstrate that the DW motion can be explained by a combination of the spin Hall effect, which generates a SOT, and Dzyaloshinskii-Moriya interaction, which stabilizes chiral Neel-type DW. Based on SOT-driven DW motion and magnetic coupling between electrically isolated ferromagnetic elements, I proposed a new type of spin logic devices. I then demonstrate the device operation by using micromagnetic modeling which involves studying the magnetic coupling induced by fringe fields from chiral DWs in perpendicularly magnetized nanowires. The last part of my thesis project reports spin transport and spin-Hall magnetoresistance (SMR) in yttrium iron garnet Y3Fe5O 12 (YIG)/NiO/Pt trilayers with varied NiO thickness. To characterize the spin transport through NiO we excite

  18. Sodium and potassium doped P-type ZnO films by sol-gel spin-coating technique

    Science.gov (United States)

    Au, Benedict Wen-Cheun; Chan, Kah-Yoong

    2017-07-01

    Zinc oxide (ZnO) is a promising material in a variety of applications including sensors, transistors and solar cells. Many researchers studied N-type ZnO films and reported enhanced properties. On the other hand, P-type ZnO films were rarely attempted due to the self-compensation effect. Success in achieving P-type ZnO films is important as it will pave the way for more advanced complementary devices. In this work, P-type sodium and potassium doped ZnO films were fabricated on glass substrates with doping concentration between 0 and 25 at.%. The influences of doping concentration on surface morphology, structural, optical and electrical properties were investigated using atomic force microscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometer, photoluminescence spectroscopy and Hall-effect electrical transport measurement system. The distinctive behavior of P-type ZnO films with different doping concentrations will be discussed.

  19. Dynamic-angle spinning and double rotation of quadrupolar nuclei

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-07-01

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

  20. Dynamic-angle spinning and double rotation of quadrupolar nuclei

    International Nuclear Information System (INIS)

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

    1991-07-01

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

  1. Effect of Rashba type spin-orbit interaction on the electronic spectrum of graphene in the presence of a hydrogenic impurity

    Science.gov (United States)

    Gökçek, N.

    2018-01-01

    The effect of Rashba spin-orbit interaction on the electronic spectrum of gapped graphene with a hydrogenic impurity in the presence of topological defects is analyzed analytically. Degenerate perturbation theory is used to investigate the dependence of electronic spectrum of gapped graphene on the strengths of impurity and Rashba spin-orbit coupling. The results show that, as the strength of Rashba spin-orbit coupling increases, pseudo-Zeeman splitting of energy levels induced by topological defects is enhanced. Therefore, it is possible to tune this pseudo-Zeeman splitting through the strength of Rashba spin-orbit coupling and of the strength of hydrogenic impurity.

  2. Executive Succession, Strategic Reorientation and Performance Growth: A Longitudinal Study in the U.S. Cement Industry

    OpenAIRE

    Michael L. Tushman; Lori Rosenkopf

    1996-01-01

    This research explores the performance consequences of CEO succession, executive team change, and strategic reorientation in different contexts. Based on team demography and organization learning ideas, we argue that CEO succession or executive team change enhances incremental organization change, while either strategic reorientation or the combination of CEO succession with executive team change triggers discontinuous organization change. We hypothesize that these contrasting intervention mo...

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

    Science.gov (United States)

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

    2014-09-01

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

  4. Spin photocurrent spectra induced by Rashba- and Dresselhaus-type circular photogalvanic effect at inter-band excitation in InGaAs/GaAs/AlGaAs step quantum wells.

    Science.gov (United States)

    Yu, Jinling; Cheng, Shuying; Lai, Yunfeng; Zheng, Qiao; Chen, Yonghai

    2014-03-19

    : Spin photocurrent spectra induced by Rashba- and Dresselhaus-type circular photogalvanic effect (CPGE) at inter-band excitation have been experimentally investigated in InGaAs/GaAs/AlGaAs step quantum wells (QWs) at room temperature. The Rashba- and Dresselhaus-induced CPGE spectra are quite similar with each other during the spectral region corresponding to the transition of the excitonic state 1H1E (the first valence subband of heavy hole to the first conduction subband of electrons). The ratio of Rashba- and Dresselhaus-induced CPGE current for the transition 1H1E is estimated to be 8.8±0.1, much larger than that obtained in symmetric QWs (4.95). Compared to symmetric QWs, the reduced well width enhances the Dresselhaus-type spin splitting, but the Rashba-type spin splitting increases more rapidly in the step QWs. Since the degree of the segregation effect of indium atoms and the intensity of build-in field in the step QWs are comparable to those in symmetric QWs, as proved by reflectance difference and photoreflectance spectra, respectively, the larger Rashba-type spin splitting is mainly induced by the additional interface introduced by step structures.

  5. Optical and magneto-optical properties of spin coated films of novel trinuclear bis(oxamato) and bis(oxamidato) type complexes

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmalic, Mohammad A. [Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Chemie, Straße der Nationen 62, D-09111 Chemnitz (Germany); Fronk, Michael [Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Physik, Reichenhainer Straße 70, D-09107 Chemnitz (Germany); Bräuer, Björn [Stanford Institute of Materials and Energy Science, Stanford University, Stanford, CA 94025 (United States); Zahn, Dietrich R.T. [Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Physik, Reichenhainer Straße 70, D-09107 Chemnitz (Germany); Salvan, Georgeta, E-mail: salvan@physik.tu-chemnitz.de [Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Physik, Reichenhainer Straße 70, D-09107 Chemnitz (Germany); Eya' ane Meva, Francois [Department of Pharmaceutical Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, BP 2701 (Cameroon); and others

    2016-12-01

    This work reports the first example of the spectroscopic measurements of the Magneto-Optical Kerr Effect (MOKE) of films being composed of trinuclear transition metal complexes on a non-transparent substrate at room temperature. The thin films of the tailor-made trinuclear bis(oxamidato) type complex 5 ([Cu{sub 3}(opbo{sup n}Pr{sub 2})(tmcd){sub 2}(NO{sub 3}){sub 2}], opbo{sup n}Pr{sub 2} = o-phenylenebis(N’-{sup n}propyloxamido, tmcd=trans-(1 R,2 R)-N,N,N′,N′-tetramethyl-cyclohexanediamine) and of the bis(oxamato) type complexes 11 ([Cu{sub 2}Ni(opbaCF{sub 3})(pmdta){sub 2}(NO{sub 3}){sub 2}], opbaCF{sub 3} = 4-trifluoromethyl-o-phenylenebis(oxamato), pmdta = N,N,N,′N″,N″-pentamethyldiethylenetriamine) and 12 ([Cu{sub 3}(opba)(bppe){sub 2}(NO{sub 3}){sub 2}] (opba = o-phenylenebis(oxamato), bppe = S-N,N-bis(2-picolyl)−1-phenylethylamine) were fabricated by spin-coating and their thicknesses in the range between 0.5 µm and 2 µm was determined by spectroscopic ellipsometry. Based on the spectroscopic ellipsometry results it was also possible to determine the optical constants of the film and compare them with the absorption of the complexes in solution in order to confirm the complex integrity after the film deposition. The fabrication of high-quality films which exhibit Kerr rotation up to 0.2 mrad (11.5 mdeg) was only possible due to tailor-made synthesis, which allows circumventing intermolecular interactions of the trinuclear complexes during the film formation. - Highlights: • Tailor-made trinuclear bis(oxamidato) and bis(oxamato) type complexes were synthesized. • Thin films (between 0.5 µm and 2 µm) were fabricated by spin-coating. • The film optical constants indicate the complex integrity after the deposition. • Film quality enabled first spectroscopic MOKE measurements of multi-nuclear complexes. • Magneto-optical Kerr rotation up to 11.5 mdeg was observed at RT (in 1.7 T).

  6. Antiferromagnetic ordering in spin-chain multiferroic Gd{sub 2}BaNiO{sub 5} studied by electronic spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. M.; Ruan, M. Y.; Cheng, J. J.; Sun, Y. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ouyang, Z. W., E-mail: zwouyang@mail.hust.edu.cn; Xia, Z. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Rao, G. H. [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-06-14

    High-field electron spin resonance (ESR) has been employed to study the antiferromagnetic (AFM) ordering state (T < T{sub N} = 55 K) of spin-chain multiferroic Gd{sub 2}BaNiO{sub 5}. The spin reorientation at T{sub SR} = 24 K is well characterized by the temperature-dependent ESR spectra. The magnetization data evidence a field-induced spin-flop transition at 2 K. The frequency-field relationship of the ESR data can be explained by conventional AFM resonance theory with uniaxial anisotropy, in good agreement with magnetization data. Related discussion on zero-field spin gap is presented.

  7. Dynamic behaviors of spin-1/2 bilayer system within Glauber-type stochastic dynamics based on the effective-field theory

    International Nuclear Information System (INIS)

    Ertaş, Mehmet; Kantar, Ersin; Keskin, Mustafa

    2014-01-01

    The dynamic phase transitions (DPTs) and dynamic phase diagrams of the kinetic spin-1/2 bilayer system in the presence of a time-dependent oscillating external magnetic field are studied by using Glauber-type stochastic dynamics based on the effective-field theory with correlations for the ferromagnetic/ferromagnetic (FM/FM), antiferromagnetic/ferromagnetic (AFM/FM) and antiferromagnetic/antiferromagnetic (AFM/AFM) interactions. The time variations of average magnetizations and the temperature dependence of the dynamic magnetizations are investigated. The dynamic phase diagrams for the amplitude of the oscillating field versus temperature were presented. The results are compared with the results of the same system within Glauber-type stochastic dynamics based on the mean-field theory. - Highlights: • The Ising bilayer system is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a re-entrant behavior

  8. Dynamic behaviors of spin-1/2 bilayer system within Glauber-type stochastic dynamics based on the effective-field theory

    Energy Technology Data Exchange (ETDEWEB)

    Ertaş, Mehmet; Kantar, Ersin, E-mail: ersinkantar@erciyes.edu.tr; Keskin, Mustafa

    2014-05-01

    The dynamic phase transitions (DPTs) and dynamic phase diagrams of the kinetic spin-1/2 bilayer system in the presence of a time-dependent oscillating external magnetic field are studied by using Glauber-type stochastic dynamics based on the effective-field theory with correlations for the ferromagnetic/ferromagnetic (FM/FM), antiferromagnetic/ferromagnetic (AFM/FM) and antiferromagnetic/antiferromagnetic (AFM/AFM) interactions. The time variations of average magnetizations and the temperature dependence of the dynamic magnetizations are investigated. The dynamic phase diagrams for the amplitude of the oscillating field versus temperature were presented. The results are compared with the results of the same system within Glauber-type stochastic dynamics based on the mean-field theory. - Highlights: • The Ising bilayer system is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a re-entrant behavior.

  9. Cross-point-type spin-transfer-torque magnetoresistive random access memory cell with multi-pillar vertical body channel MOSFET

    Science.gov (United States)

    Sasaki, Taro; Endoh, Tetsuo

    2018-04-01

    In this paper, from the viewpoint of cell size and sensing margin, the impact of a novel cross-point-type one transistor and one magnetic tunnel junction (1T–1MTJ) spin-transfer-torque magnetoresistive random access memory (STT-MRAM) cell with a multi-pillar vertical body channel (BC) MOSFET is shown for high density and wide sensing margin STT-MRAM, with a 10 ns writing period and 1.2 V V DD. For that purpose, all combinations of n/p-type MOSFETs and bottom/top-pin MTJs are compared, where the diameter of MTJ (D MTJ) is scaled down from 55 to 15 nm and the tunnel magnetoresistance (TMR) ratio is increased from 100 to 200%. The results show that, benefiting from the proposed STT-MRAM cell with no back bias effect, the MTJ with a high TMR ratio (200%) can be used in the design of smaller STT-MRAM cells (over 72.6% cell size reduction), which is a difficult task for conventional planar MOSFET based design.

  10. Taking the road less taken: reorienting the state for periurban water security

    NARCIS (Netherlands)

    Narain, Vishal; Ranjan, Pranay; Vij, S.; Dewan, Aman

    2017-01-01

    This paper describes the intervention strategy to improve water security in Sultanpur, a village in periurban Gurgaon, India. Most approaches to improving natural resource management in periurban contexts focus on mobilising the community; little attention is paid to reorienting the state or

  11. Practicalities and challenges in re-orienting the health system in Zambia for treating chronic conditions.

    NARCIS (Netherlands)

    Aantjes, C.J.; Quinlan, T.K.C.; Bunders-Aelen, J.G.F.

    2014-01-01

    Background: The rapid evolution in disease burdens in low- and middle income countries is forcing policy makers to re-orient their health system towards a system which has the capability to simultaneously address infectious and non-communicable diseases. This paper draws on two different but

  12. Social reorientation in adolescence : neurobiological changes and individual differences in empathic concern

    NARCIS (Netherlands)

    Overgaauw, Sandy

    2015-01-01

    One of the most prominent changes in adolescence is social reorientation. In other words, adolescents develop more intimate relationships with peers, they discover what it is like to be involved in a romantic relationship, and they take (social) risks by for example showing risky driving in the

  13. Use of Geometric Properties of Landmark Arrays for Reorientation Relative to Remote Cities and Local Objects

    Science.gov (United States)

    Mou, Weimin; Nankoo, Jean-François; Zhou, Ruojing; Spetch, Marcia L.

    2014-01-01

    Five experiments investigated how human adults use landmark arrays in the immediate environment to reorient relative to the local environment and relative to remote cities. Participants learned targets' directions with the presence of a proximal 4 poles forming a rectangular shape and an array of more distal poles forming a rectangular shape. Then…

  14. Cometary spin-down

    Science.gov (United States)

    Agarwal, Jessica

    2018-01-01

    The rotation rate of a comet more than halved in two months -- a much greater change than has previously been observed. This suggests that the comet is in a distinct evolutionary state and might soon reorient itself.

  15. Time-dependent solution for reorientation of rotating tidally deformed visco-elastic bodies

    Science.gov (United States)

    Hu, Haiyang; van der Wal, Wouter; Vermeersen, Bert

    2017-04-01

    Many icy satellites or planets contain features which suggest a (past) reorientation of the body, such as the tiger stripes on Enceladus and the heart-shaped Sputnik Planum on Pluto. Most of these icy bodies are tidally locked and this creates a large tidal bulge which is about three times of its centrifugal (equatorial) bulge. To study the reorientation of such rotating tidally deformed body is complicated and most previous studies apply the so-called fluid limit method. The fluid limit approach ignores the viscous response of the body and assumes that it immediately reaches its fluid limit when simulating the reorientation due to a changing load. As a result, this method can only simulate cases when the change in the load is much slower than the dominant viscous modes of the body. For other kinds of load, for instance, a Heaviside load due to an impact which creates an instant relocation of mass, it does not give us a prediction of how the reorientation is accomplished (e.g. How fast? Along which path?). We establish a new method which can give an accurate time-dependent solution for reorientation of rotating tidally deformed bodies. Our method can be applied both semi-analytically or numerically (with finite element method) to include features such as lateral heterogeneity or non-linear material. We also present an extension of our method to simulate the effect of a fossil bulge. With our method, we show that reorientation of a tidally deformed body driven by a positive mass anomaly near the poles has a preference for rotating around the tidal axis instead of towards it, contrary to predictions in previous studies. References Hu, H., W. van der Wal and L.L.A. Vermeersen (2017). A numerical method for reorientation of rotating tidally deformed visco-elastic bodies. Journal of Geophysical Research: Planets, doi:10.1002/2016JE005114, 2016JE005114. Matsuyama, I. and Nimmo, F. (2007). Rotational stability of tidally deformed planetary bodies. Journal of Geophysical

  16. Zero field spin splitting in asymmetric quantum wells

    International Nuclear Information System (INIS)

    Hao Yafei

    2012-01-01

    Spin splitting of asymmetric quantum wells is theoretically investigated in the absence of any electric field, including the contribution of interface-related Rashba spin-orbit interaction as well as linear and cubic Dresselhaus spin-orbit interaction. The effect of interface asymmetry on three types of spin-orbit interaction is discussed. The results show that interface-related Rashba and linear Dresselhaus spin-orbit interaction can be increased and cubic Dresselhaus spin-orbit interaction can be decreased by well structure design. For wide quantum wells, the cubic Dresselhaus spin-orbit interaction dominates under certain conditions, resulting in decreased spin relaxation time.

  17. Use of geometric properties of landmark arrays for reorientation relative to remote cities and local objects.

    Science.gov (United States)

    Mou, Weimin; Nankoo, Jean-François; Zhou, Ruojing; Spetch, Marcia L

    2014-03-01

    Five experiments investigated how human adults use landmark arrays in the immediate environment to reorient relative to the local environment and relative to remote cities. Participants learned targets' directions with the presence of a proximal 4 poles forming a rectangular shape and an array of more distal poles forming a rectangular shape. Then participants were disoriented and pointed to targets with the presence of the proximal poles or the distal poles. Participants' orientation was estimated by the mean of their pointing error across targets. The targets could be 7 objects in the immediate local environment in which the poles were located or 7 cities around Edmonton (Alberta, Canada) where the experiments occurred. The directions of the 7 cities could be learned from reading a map first and then from pointing to the cities when the poles were presented. The directions of the 7 cities could also be learned from viewing labels of cities moving back and forth in the specific direction in the immediate local environment in which the poles were located. The shape of the array of the distal poles varied in salience by changing the number of poles on each edge of the rectangle (2 vs. 34). The results showed that participants regained their orientation relative to local objects using the distal poles with 2 poles on each edge; participants could not reorient relative to cities using the distal pole array with 2 poles on each edge but could reorient relative to cities using the distal pole array with 34 poles on each edge. These results indicate that use of cues in reorientation depends not only on the cue salience but also on which environment people need to reorient to.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  19. Interference Spins

    DEFF Research Database (Denmark)

    Popovski, Petar; Simeone, Osvaldo; Nielsen, Jimmy Jessen

    2015-01-01

    on traffic load and interference condition leads to performance gains. In this letter, a general network of multiple interfering two-way links is studied under the assumption of a balanced load in the two directions for each link. Using the notion of interference spin, we introduce an algebraic framework...

  20. Differential Gene Expression in Brassica rapa Roots After Reorientation and Clinorotation.

    Science.gov (United States)

    Edge, Andrea; Hasenstein, Karl H.

    Seedlings align their growth axes parallel to the gravity vector. Any growth adjustment affects genes. We examined these changes in Brassica rapa roots that were reoriented and clinorotated. Gene expression levels related to the actin cytoskeleton (ACT7 and ADK1) and auxin transport (IAA5, PIN1, PIN3, AGR1, ARG1) were assessed in roots grown for 42 hours and then either reoriented to 90° for 15 min, 1, 2 and 3 hours or clinorotated vertically or horizontally for 42 hrs at 2 rpm. After these treatments, roots from 20 seedlings were divided into three sections, the root tip, elongation zone, and maturation zone. The samples from corresponding treatments were combined for RNA extraction, reverse transcription and analysis by quantitative PCR. The results show that gene expression changes in response to duration of reorientation and orientation during clinorotation. All genes, except PIN1 and AGR1 were upregulated in the tip after 2 hours of reorientation. Expression of genes also varied between the root sections except for PIN1, which was uniformly expressed. ADK1 was the only gene that showed consistent down-regulation in all three root regions in vertically and horizontally clinorotated roots (ca 30% of controls). In contrast, ADK1 was upregulated (more than 150 fold) in the tip of roots that were reoriented for 2 hours but little upregulation after one hour (less than 2 fold compared to controls). Our results indicate that gene expression during the gravitropic response changes over time with the tip region being the most dynamic tissue in the root. The large upregulation of ADK1 at 2 h after reorientation may be related to the persistence of the gravitropic response. Because of the variability of the expression profiles, analyses that are based on the entire root miss tissue specific changes in gene expression. Differences in gene expression after vertical and horizontal clinorotation indicates that the graviresponse system is sensitive not just to the magnitude

  1. Photoinduced reorientation and polarization holography in a new photopolymer with 4-methoxy-N-benzylideneaniline side groups

    Directory of Open Access Journals (Sweden)

    Nobuhiro Kawatsuki

    2013-08-01

    Full Text Available The photoinduced reorientation and surface relief (SR formation behaviors of a novel photosensitive polymer, which was transparent in visible region, were investigated using linearly polarized-313-nm light and holographic exposure with a 325-nm He-Cd laser. The polymer was comprised of photosensitive 4-methoxy-N-benzylideneaniline side groups, and exhibited a sufficient photoinduced molecular reorientation with a birefringence of 0.11. Holographic exposure generated a SR structure, which had a periodical molecular reorientation that depended on the polarization of the interference beams. The generated SR height was ∼212 nm, and the inscription of a double holographic exposure yielded a two-dimensional SR structure.

  2. In situ neutron diffraction study of twin reorientation and pseudoplastic strain in Ni-Mn-Ga single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, Alexandru Dan [ORNL

    2011-01-01

    Twin variant reorientation in single-crystal Ni-Mn-Ga during quasi-static mechanical compression was studied using in situ neutron diffraction. The volume fraction of reoriented twin variants for different stress amplitudes were obtained from the changes in integrated intensities of high-order neutron diffraction peaks. It is shown that, during compressive loading, {approx}85% of the twins were reoriented parallel to the loading direction resulting in a maximum pseudoplasticstrain of {approx}5.5%, which is in agreement with measured macroscopic strain.

  3. In situ neutron diffraction study of twin reorientation and pseudoplastic strain in Ni-Mn-Ga single crystals

    International Nuclear Information System (INIS)

    Pramanick, A.; An, K.; Stoica, A.D.; Wang, X.-L.

    2011-01-01

    Twin variant reorientation in single-crystal Ni-Mn-Ga during quasi-static mechanical compression was studied using in situ neutron diffraction. The volume fraction of reoriented twin variants for different stress amplitudes were obtained from the changes in integrated intensities of high-order neutron diffraction peaks. It is shown that, during compressive loading, ∼85% of the twins were reoriented parallel to the loading direction resulting in a maximum pseudoplastic strain of ∼5.5%, which is in agreement with measured macroscopic strain.

  4. Spin glass type behaviour in quasi 1D insulating compounds with impurities: FeMg2BO5, FeMgBO4

    International Nuclear Information System (INIS)

    Wiedenmann, A.; Chevalier, R.

    1978-01-01

    In a first part structural and chemical characteristics are recalled. In a second part experimental results are given, showing that magnetic behaviour is similar to the behaviour of spin glasses but are not metallic [fr

  5. Cerebral Hemodynamic and White Matter Changes of Type 2 Diabetes Revealed by Multi-TI Arterial Spin Labeling and Double Inversion Recovery Sequence

    Directory of Open Access Journals (Sweden)

    Yelong Shen

    2017-12-01

    Full Text Available Diabetes has been reported to affect the microvasculature and lead to cerebral small vessel disease (SVD. Past studies using arterial spin labeling (ASL at single post-labeling delay reported reduced cerebral blood flow (CBF in patients with type 2 diabetes. The purpose of this study was to characterize cerebral hemodynamic changes of type 2 diabetes using a multi-inversion-time 3D GRASE pulsed ASL (PASL sequence to simultaneously measure CBF and bolus arrival time (BAT. Thirty-six patients with type 2 diabetes (43–71 years, 17 male and 36 gender- and age-matched control subjects underwent MRI scans at 3 T. Mean CBF/BAT values were computed for gray and white matter (GM and WM of each subject, while a voxel-wise analysis was performed for comparison of regional CBF and BAT between the two groups. In addition, white matter hyperintensities (WMHs were detected by a double inversion recovery (DIR sequence with relatively high sensitivity and spatial resolution. Mean CBF of the WM, but not GM, of the diabetes group was significantly lower than that of the control group (p < 0.0001. Regional CBF decreases were detected in the left middle occipital gyrus (p = 0.0075, but failed to reach significance after correction of partial volume effects. BAT increases were observed in the right calcarine fissure (p < 0.0001, left middle occipital gyrus (p < 0.0001, and right middle occipital gyrus (p = 0.0011. Within the group of diabetic patients, BAT in the right middle occipital gyrus was positively correlated with the disease duration (r = 0.501, p = 0.002, BAT in the left middle occipital gyrus was negatively correlated with the binocular visual acuity (r = −0.408, p = 0.014. Diabetic patients also had more WMHs than the control group (p = 0.0039. Significant differences in CBF, BAT, and more WMHs were observed in patients with diabetes, which may be related to impaired vision and risk of SVD of type 2 diabetes.

  6. In a spin at Brookhaven spin physics

    CERN Document Server

    Makdisi, Y I

    2003-01-01

    The mysterious quantity that is spin took centre stage at Brookhaven for the SPIN2002 meeting last September. The 15th biennial International Spin Physics Symposium (SPIN2002) was held at Brookhaven National Laboratory on 9-14 September 2002. Some 250 spin enthusiasts attended, including experimenters and theorists in both nuclear and high-energy physics, as well as accelerator physicists and polarized target and polarized source experts. The six-day symposium included 23 plenary talks and 150 parallel talks. SPIN2002 was preceded by a one-day spin physics tutorial for students, postdocs, and anyone else who felt the need for a refresher course. (2 refs).

  7. Development and test of model apparatus of non-contact spin processor for photo mask production applying radial-type superconducting magnetic bearing

    International Nuclear Information System (INIS)

    Saito, Kimiyo; Fukui, Satoshi; Maezawa, Masaru; Ogawa, Jun; Oka, Tetsuo; Sato, Takao

    2013-01-01

    Highlights: ► We develop test spinner for non-contact spinning process in photo mask production. ► This test spinner shows improved spinning ability compared with our previous one. ► Large vertical movement of turn table still occurs during acceleration. ► Method to control vertical movement of turn table should be developed in next step. -- Abstract: In semiconductor devices, miniaturization of circuit patterning on wafers is required for higher integrations of circuit elements. Therefore, very high tolerance and quality are also required for patterning of microstructures of photo masks. The deposition of particulate dusts generated from mechanical bearings of the spin processor in the patterns of the photo mask is one of main causes of the deterioration of pattern preciseness. In our R and D, application of magnetic bearing utilizing bulk high temperature superconductors to the spin processors has been proposed. In this study, we develop a test spinner for the non-contact spinning process in the photo mask production system. The rotation test by using this test spinner shows that this test spinner accomplishes the improvement of the spinning ability compared with the test spinner developed in our previous study. This paper describes the rotation test results of the new test spinner applying the magnetic bearing with bulk high temperature superconductors

  8. Spin-Circuit Representation of Spin Pumping

    Science.gov (United States)

    Roy, Kuntal

    2017-07-01

    Circuit theory has been tremendously successful in translating physical equations into circuit elements in an organized form for further analysis and proposing creative designs for applications. With the advent of new materials and phenomena in the field of spintronics and nanomagnetics, it is imperative to construct the spin-circuit representations for different materials and phenomena. Spin pumping is a phenomenon by which a pure spin current can be injected into the adjacent layers. If the adjacent layer is a material with a high spin-orbit coupling, a considerable amount of charge voltage can be generated via the inverse spin Hall effect allowing spin detection. Here we develop the spin-circuit representation of spin pumping. We then combine it with the spin-circuit representation for the materials having spin Hall effect to show that it reproduces the standard results as in the literature. We further show how complex multilayers can be analyzed by simply writing a netlist.

  9. Hydride reorientation in Zircaloy-4 examined by in situ synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Weekes, H.E. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Jones, N.G. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Lindley, T.C. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Dye, D., E-mail: david.dye@imperial.ac.uk [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom)

    2016-09-15

    The phenomenon of stress-reorientation has been investigated using in situ X-ray diffraction during the thermomechanical cycling of hydrided Zircaloy-4 tensile specimens. Results have shown that loading along a sample’s transverse direction (TD) leads to a greater degree of hydride reorientation when compared to rolling direction (RD)-aligned samples. The elastic lattice micro-strains associated with radially oriented hydrides have been revealed to be greater than those oriented circumferentially, a consequence of strain accommodation. Evidence of hydride redistribution after cycling, to α-Zr grains oriented in a more favourable orientation when under an applied stress, has also been observed and its behaviour has been found to be highly dependent on the loading axis. Finally, thermomechanical loading across multiple cycles has been shown to reduce the difference in terminal solid solubility of hydrogen during dissolution (TSS{sub D,H}) and precipitation (TSS{sub P,H}).

  10. A 3D finite strain phenomenological constitutive model for shape memory alloys considering martensite reorientation

    Science.gov (United States)

    Arghavani, J.; Auricchio, F.; Naghdabadi, R.; Reali, A.; Sohrabpour, S.

    2010-06-01

    Most devices based on shape memory alloys experience both finite deformations and non-proportional loading conditions in engineering applications. This motivates the development of constitutive models considering finite strain as well as martensite variant reorientation. To this end, in the present article, based on the principles of continuum thermodynamics with internal variables, a three-dimensional finite strain phenomenological constitutive model is proposed taking its basis from the recent model in the small strain regime proposed by Panico and Brinson (J Mech Phys Solids 55:2491-2511, 2007). In the finite strain constitutive model derivation, a multiplicative decomposition of the deformation gradient into elastic and inelastic parts, together with an additive decomposition of the inelastic strain rate tensor into transformation and reorientation parts is adopted. Moreover, it is shown that, when linearized, the proposed model reduces exactly to the original small strain model.

  11. Modularity as a fish (Xenotoca eiseni) views it: conjoining geometric and nongeometric information for spatial reorientation.

    Science.gov (United States)

    Sovrano, Valeria Anna; Bisazza, Angelo; Vallortigara, Giorgio

    2003-07-01

    When disoriented in a closed rectangular tank, fish (Xenotoca eiseni) reoriented in accord with the large-scale shape of the environment, but they were also able to conjoin geometric information with nongeometric properties such as the color of a wall or the features provided by panels located at the corners of the tank. Fish encoded geometric information even when featural information sufficed to solve the spatial task. When tested after transformations that altered the original arrangement of the panels, fish were more affected by those transformations that modified the geometric relationship between the target and the shape of the environment. Finally, fish appeared unable to use nongeometric information provided by distant panels. These findings show that a reorientation mechanism based on geometry is widespread among vertebrates, though the joint use of geometric and nongeometric cues by fish suggest that the degree of information encapsulation of the mechanism varies considerably between species.

  12. Assessing human reorientation ability inside virtual reality environments: the effects of retention interval and landmark characteristics.

    Science.gov (United States)

    Bosco, Andrea; Picucci, Luciana; Caffò, Alessandro O; Lancioni, Giulio E; Gyselinck, Valérie

    2008-12-01

    The purpose of the present study was to assess the navigational behaviour of adult humans following a disorientation procedure that perturbed their egocentric frame of reference. The assessment was carried out in a virtual reality (VR) environment by manipulating the disorientation procedure, the retention interval, the relative positions of target and landmark. The results of experiment I demonstrated that adding a physical rotation to a virtual disorientation procedure did not yield an additional decrease in searching performance. The results of experiment II showed that shortening the delay between study and test phase decreased the errors more markedly for geometric than landmark ones. An orientation specificity effect due to the manipulation of the relative position between target and landmark was discussed across the experiments. In conclusion, VR seemed to be a valuable method for studying human reorientation. Moreover, the virtual experimental setting involved here promoted knowledge of the relationship between working memory and spatial reorientation paradigm.

  13. Spin Coherence in Semiconductor Nanostructures

    National Research Council Canada - National Science Library

    Flatte, Michael E

    2006-01-01

    ... dots, tuning of spin coherence times for electron spin, tuning of dipolar magnetic fields for nuclear spin, spontaneous spin polarization generation and new designs for spin-based teleportation and spin transistors...

  14. Spinning Disk Confocal System

    Science.gov (United States)

    2006-06-01

    high temporal resolution. An instrument has been developed for exactly this type of live-cell imaging. This new instrument scans 1000 microbeams across...Imaging System. Instead of scanning a single laser beam across the cell, this new instrument scans 1000 microbeams simultaneously using a spinning...multipoint-excitation, multipoint- emission characteristics of UltraView RS, which confers three main advantages over traditional beam scanning LSCMs for

  15. Communication: On the origin of the non-Arrhenius behavior in water reorientation dynamics

    OpenAIRE

    Stirnemann, Guillaume; Laage, Damien

    2012-01-01

    International audience; We combine molecular dynamics simulations and analytic modeling to determine the origin of the non-Arrhenius temperature dependence of liquid water's reorientation and hydrogen-bond dynamics between 235 K and 350 K. We present a quantitative model connecting hydrogen-bond exchange dynamics to local structural fluctuations, measured by the asphericity of Voronoi cells associated with each water molecule. For a fixed local structure the regular Arrhenius behavior is reco...

  16. Practicalities and challenges in re-orienting the health system in Zambia for treating chronic conditions

    OpenAIRE

    Aantjes, Carolien J; Quinlan, Tim KC; Bunders, Joske FG

    2014-01-01

    Background The rapid evolution in disease burdens in low- and middle income countries is forcing policy makers to re-orient their health system towards a system which has the capability to simultaneously address infectious and non-communicable diseases. This paper draws on two different but overlapping studies which examined how actors in the Zambian health system are re-directing their policies, strategies and service structures to include the provision of health care for people with chronic...

  17. Social reorientation in adolescence: neurobiological changes and individual differences in empathic concern

    OpenAIRE

    Overgaauw, Sandy

    2015-01-01

    One of the most prominent changes in adolescence is social reorientation. In other words, adolescents develop more intimate relationships with peers, they discover what it is like to be involved in a romantic relationship, and they take (social) risks by for example showing risky driving in the presence of friends. Given that social networks with peers become central elements in the adolescent’s life, investigating the role of individual differences related to the development of social reorie...

  18. Reorientation of Magnetic Graphene Oxide Nanosheets in Crosslinked Quaternized Polyvinyl Alcohol as Effective Solid Electrolyte

    OpenAIRE

    Jia-Shuin Lin; Wei-Ting Ma; Chao-Ming Shih; Bor-Chern Yu; Li-Wei Teng; Yi-Chun Wang; Kong-Wei Cheng; Fang-Chyou Chiu; Shingjiang Jessie Lue

    2016-01-01

    This work aims to clarify the effect of magnetic graphene oxide (GO) reorientation in a polymer matrix on the ionic conduction and methanol barrier properties of nanocomposite membrane electrolytes. Magnetic iron oxide (Fe3O4) nanoparticles were prepared and dispersed on GO nanosheets (GO-Fe3O4). The magnetic GO-Fe3O4 was imbedded into a quaternized polyvinyl alcohol (QPVA) matrix and crosslinked (CL-) with glutaraldehyde (GA) to obtain a polymeric nanocomposite. A magnetic field was applied ...

  19. Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia.

    Science.gov (United States)

    Keane, James T; Matsuyama, Isamu; Kamata, Shunichi; Steckloff, Jordan K

    2016-12-01

    Pluto is an astoundingly diverse, geologically dynamic world. The dominant feature is Sputnik Planitia-a tear-drop-shaped topographic depression approximately 1,000 kilometres in diameter possibly representing an ancient impact basin. The interior of Sputnik Planitia is characterized by a smooth, craterless plain three to four kilometres beneath the surrounding rugged uplands, and represents the surface of a massive unit of actively convecting volatile ices (N 2 , CH 4 and CO) several kilometres thick. This large feature is very near the Pluto-Charon tidal axis. Here we report that the location of Sputnik Planitia is the natural consequence of the sequestration of volatile ices within the basin and the resulting reorientation (true polar wander) of Pluto. Loading of volatile ices within a basin the size of Sputnik Planitia can substantially alter Pluto's inertia tensor, resulting in a reorientation of the dwarf planet of around 60 degrees with respect to the rotational and tidal axes. The combination of this reorientation, loading and global expansion due to the freezing of a possible subsurface ocean generates stresses within the planet's lithosphere, resulting in a global network of extensional faults that closely replicate the observed fault networks on Pluto. Sputnik Planitia probably formed northwest of its present location, and was loaded with volatiles over million-year timescales as a result of volatile transport cycles on Pluto. Pluto's past, present and future orientation is controlled by feedbacks between volatile sublimation and condensation, changing insolation conditions and Pluto's interior structure.

  20. Stable panoramic views facilitate snap-shot like memories for spatial reorientation in homing pigeons.

    Directory of Open Access Journals (Sweden)

    Tommaso Pecchia

    Full Text Available Following spatial disorientation, animals can reorient themselves by relying on geometric cues (metric and sense specified both by the macroscopic surface layout of an enclosed space and prominent visual landmarks in arrays. Whether spatial reorientation in arrays of landmarks is based on explicit representation of the geometric cues is a matter of debate. Here we trained homing pigeons (Columba livia to locate a food-reward in a rectangular array of four identical or differently coloured pipes provided with four openings, only one of which allowed the birds to have access to the reward. Pigeons were trained either with a stable or a variable position of the opening on pipes, so that they could view the array either from the same or a variable perspective. Explicit mapping of configural geometry would predict successful reorientation irrespective of access condition. In contrast, we found that a stable view of the array facilitated spatial learning in homing pigeons, likely through the formation of snapshot-like memories.

  1. Spatial reorientation decline in aging: the combination of geometry and landmarks.

    Science.gov (United States)

    Caffò, Alessandro O; Lopez, Antonella; Spano, Giuseppina; Serino, Silvia; Cipresso, Pietro; Stasolla, Fabrizio; Savino, Michelina; Lancioni, Giulio E; Riva, Giuseppe; Bosco, Andrea

    2017-07-20

    The study is focused on the assessment of reorientation skills in a sample of community-dwelling elderly people, manipulating landmarks and geometric (layout) information. A neuropsychological assessment was administered to 286 elderly participants, divided into six groups (healthy controls, HC; four subgroups of participants with mild cognitive impairment, MCI; participants with probable dementia, Prob_D) and tested with the Virtual Reorientation Test (VReoT). VReoT manipulated different spatial cues: geometry and landmarks (proximal and distal). Compared with HC, participants with MCI and Prob_D showed to be impaired in tasks involving geometry, landmarks and a combination of them. Both single and multiple domain impairment in MCI had an impact on reorientation performance. Moreover, VReoT was marginally able to discriminate between amnesic and non-amnesic MCI. The occurrence of getting lost events seemed to be associated to learning of geometric information. The associative strength between landmark and target plays an important role in affecting spatial orientation performance of cognitively impaired participants. Geometry significantly supports landmark information and becomes helpful with the increase of cognitive impairment which is linked to a decrement in landmark encoding. VReoT seems to represent a reliable evaluation supplement for spatial orientation deficits in prodromal stages of dementia.

  2. Spin transport and relaxation in graphene

    International Nuclear Information System (INIS)

    Han Wei; McCreary, K.M.; Pi, K.; Wang, W.H.; Li Yan; Wen, H.; Chen, J.R.; Kawakami, R.K.

    2012-01-01

    We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for

  3. Spin flexoelectricity and chiral spin structures in magnetic films

    International Nuclear Information System (INIS)

    Pyatakov, A.P.; Sergeev, A.S.; Mikailzade, F.A.; Zvezdin, A.K.

    2015-01-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism are discussed. The phenomenological arguments based on the geometrical idea of curvature-induced effects are supported by analysis of the microscopic mechanisms of spin flexoelectricity based on three-site ion indirect exchange and twisted RKKY interaction models. - Highlights: • Magnetic structure formation in thin films is analogous to flexoelectric phenomena in crystals. • The microscopic mechanism of spin flexoelectricity is the antisymmetric exchange. • Spin cycloid in thin film of metals can be the result of Rashba interaction in 2DEG. • The chirality-dependent Néel-type magnetic domain wall motion is observed in electric field

  4. Spin flexoelectricity and chiral spin structures in magnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Pyatakov, A.P., E-mail: pyatakov@physics.msu.ru [M.V. Lomonosov Moscow State University, Leninskie gori, Moscow 119991 (Russian Federation); Sergeev, A.S. [M.V. Lomonosov Moscow State University, Leninskie gori, Moscow 119991 (Russian Federation); Mikailzade, F.A. [Department of Physics, Gebze Technical University, Gebze, 41400 Kocaeli (Turkey); Zvezdin, A.K. [A.M. Prokhorov General Physics Institute, Vavilova St., 38, Moscow 119991 (Russian Federation)

    2015-06-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism are discussed. The phenomenological arguments based on the geometrical idea of curvature-induced effects are supported by analysis of the microscopic mechanisms of spin flexoelectricity based on three-site ion indirect exchange and twisted RKKY interaction models. - Highlights: • Magnetic structure formation in thin films is analogous to flexoelectric phenomena in crystals. • The microscopic mechanism of spin flexoelectricity is the antisymmetric exchange. • Spin cycloid in thin film of metals can be the result of Rashba interaction in 2DEG. • The chirality-dependent Néel-type magnetic domain wall motion is observed in electric field.

  5. Oxidation-decomposition facilitated reorientation of nanoparticles in reactively sintered (Ni{sub 0.33}Co{sub 0.67}){sub 1-{delta}}O polycrystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.-Y.; Shen Pouyan; Hwang, S.-L

    2003-02-25

    (Ni{sub 0.33}Co{sub 0.67}){sub 1-{delta}}O polycrystals with rock salt structure and a bimodal size distribution due to reactive sintering at 1000 deg. C were subject to annealing at 720 deg. C for 2-72 h in air and studied by analytical electron microscopy with regard to the effect of oxidation decomposition on the reorientation of nanoparticles in host grains. Upon annealing, the nanoparticles rapidly oxidized as spinel structure progressively Co-richer, whereas the host protoxide grains with rock salt-type structure progressively Ni-richer. The spinel particles less than 100 nm in size readily detached from grain boundaries and fell into parallel epitaxial relationship with respect to the host protoxide grains sharing a coherent interface. Such a Brownian-type reorientation process, in terms of anchorage release at interphase interface and driven by epitaxy energy cusp, at a rather low apparent homologous temperature (T/T{sub m}=0.45) was facilitated by oxidation decomposition process and nanometer-size effect.

  6. Digital operation and eye diagrams in spin-lasers

    International Nuclear Information System (INIS)

    Wasner, Evan; Bearden, Sean; Žutić, Igor; Lee, Jeongsu

    2015-01-01

    Digital operation of lasers with injected spin-polarized carriers provides an improved operation over their conventional counterparts with spin-unpolarized carriers. Such spin-lasers can attain much higher bit rates, crucial for optical communication systems. The overall quality of a digital signal in these two types of lasers is compared using eye diagrams and quantified by improved Q-factors and bit-error-rates in spin-lasers. Surprisingly, an optimal performance of spin-lasers requires finite, not infinite, spin-relaxation times, giving a guidance for the design of future spin-lasers

  7. Dynamical transition in molecular glasses and proteins observed by spin relaxation of nitroxide spin probes and labels

    Science.gov (United States)

    Golysheva, Elena A.; Shevelev, Georgiy Yu.; Dzuba, Sergei A.

    2017-08-01

    In glassy substances and biological media, dynamical transitions are observed in neutron scattering that manifests itself as deviations of the translational mean-squared displacement, , of hydrogen atoms from harmonic dynamics. In biological media, the deviation occurs at two temperature intervals, at ˜100-150 K and at ˜170-230 K, and it is attributed to the motion of methyl groups in the former case and to the transition from harmonic to anharmonic or diffusive motions in the latter case. In this work, electron spin echo (ESE) spectroscopy—a pulsed version of electron paramagnetic resonance—is applied to study the spin relaxation of nitroxide spin probes and labels introduced in molecular glass former o-terphenyl and in protein lysozyme. The anisotropic contribution to the rate of the two-pulse ESE decay, ΔW, is induced by spin relaxation appearing because of restricted orientational stochastic molecular motion; it is proportional to τc, where is the mean-squared angle of reorientation of the nitroxide molecule around the equilibrium position and τc is the correlation time of reorientation. The ESE time window allows us to study motions with τc τc temperature dependence shows a transition near 240 K, which is in agreement with the literature data on . For spin probes of essentially different size, the obtained data were found to be close, which evidences that motion is cooperative, involving a nanocluster of several neighboring molecules. For the dry lysozyme, the τc values below 260 K were found to linearly depend on the temperature in the same way as it was observed in neutron scattering for . As spin relaxation is influenced only by stochastic motion, the harmonic motions seen in ESE must be overdamped. In the hydrated lysozyme, ESE data show transitions near 130 K for all nitroxides, near 160 K for the probe located in the hydration layer, and near 180 K for the label in the protein interior. For this system, the two latter transitions are not

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

    KAUST Repository

    Wang, Xuhui

    2014-02-07

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

  9. Heat and spin interconversion

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  10. Vibrations and reorientations of H2O molecules in [Sr(H2O)6]Cl2 studied by Raman light scattering, incoherent inelastic neutron scattering and proton magnetic resonance.

    Science.gov (United States)

    Hetmańczyk, Joanna; Hetmańczyk, Lukasz; Migdał-Mikuli, Anna; Mikuli, Edward; Florek-Wojciechowska, Małgorzata; Harańczyk, Hubert

    2014-04-24

    Vibrational-reorientational dynamics of H2O ligands in the high- and low-temperature phases of [Sr(H2O)6]Cl2 was investigated by Raman Spectroscopy (RS), proton magnetic resonance ((1)H NMR), quasielastic and inelastic incoherent Neutron Scattering (QENS and IINS) methods. Neutron powder diffraction (NPD) measurements, performed simultaneously with QENS, did not indicated a change of the crystal structure at the phase transition (detected earlier by differential scanning calorimetry (DSC) at TC(h)=252.9 K (on heating) and at TC(c)=226.5K (on cooling)). Temperature dependence of the full-width at half-maximum (FWHM) of νs(OH) band at ca. 3248 cm(-1) in the RS spectra indicated small discontinuity in the vicinity of phase transition temperature, what suggests that the observed phase transition may be associated with a change of the H2O reorientational dynamics. However, an activation energy value (Ea) for the reorientational motions of H2O ligands in both phases is nearly the same and equals to ca. 8 kJ mol(-1). The QENS peaks, registered for low temperature phase do not show any broadening. However, in the high temperature phase a small QENS broadening is clearly visible, what implies that the reorientational dynamics of H2O ligands undergoes a change at the phase transition. (1)H NMR line is a superposition of two powder Pake doublets, differentiated by a dipolar broadening, suggesting that there are two types of the water molecules in the crystal lattice of [Sr(H2O)6]Cl2 which are structurally not equivalent average distances between the interacting protons are: 1.39 and 1.18 Å. However, their reorientational dynamics is very similar (τc=3.3⋅10(-10) s). Activation energies for the reorientational motion of these both kinds of H2O ligands have nearly the same values in an experimental error limit: and equal to ca. 40 kJ mole(-1). The phase transition is not seen in the (1)H NMR spectra temperature dependencies. Infrared (IR), Raman (RS) and inelastic

  11. Nuclear spin pumping and electron spin susceptibilities

    NARCIS (Netherlands)

    Danon, J.; Nazarov, Y.V.

    2011-01-01

    In this work we present a new formalism to evaluate the nuclear spin dynamics driven by hyperfine interaction with nonequilibrium electron spins. To describe the dynamics up to second order in the hyperfine coupling it suffices to evaluate the susceptibility and fluctuations of the electron spin.

  12. Resting-state functional connectivity of ventral parietal regions associated with attention reorienting and episodic recollection

    Directory of Open Access Journals (Sweden)

    Sander M Daselaar

    2013-02-01

    Full Text Available In functional neuroimaging studies, ventral parietal cortex (VPC is recruited by very different cognitive tasks. Explaining the contributions VPC to these tasks has become a topic of intense study and lively debate. Perception studies frequently find VPC activations during tasks involving attention-reorienting, and memory studies frequently find them during tasks involving episodic recollection. According to the Attention to Memory (AtoM model, both phenomena can be explained by the same VPC function: bottom-up attention. Yet, a recent functional MRI (fMRI meta-analysis suggested that attention-reorienting activations are more frequent in anterior VPC, whereas recollection activations are more frequent in posterior VPC. Also, there is evidence that anterior and posterior VPC regions have different functional connectivity patterns. To investigate these issues, we conducted a resting-state functional connectivity analysis using as seeds the center-of-mass of attention-reorienting and recollection activations in the meta-analysis, which were located in the supramarginal gyrus (SMG, around the temporo-parietal junction—TPJ and in the angular gyrus (AG, respectively. The SMG seed showed stronger connectivity with ventrolateral prefrontal cortex (VLPFC and occipito-temporal cortex, whereas the AG seed showed stronger connectivity with the hippocampus and default network regions. To investigate whether these connectivity differences were graded or sharp, VLPFC and hippocampal connectivity was measured in VPC regions traversing through the SMG and AG seeds. The results showed a graded pattern: VLPFC connectivity gradually decreases from SMG to AG, whereas hippocampal connectivity gradually increases from SMG to AG. Importantly, both gradients showed an abrupt break when extended beyond VPC borders. This finding suggests that functional differences between SMG and AG are more subtle than previously thought. These connectivity differences can be

  13. Reorientation of Magnetic Graphene Oxide Nanosheets in Crosslinked Quaternized Polyvinyl Alcohol as Effective Solid Electrolyte

    Directory of Open Access Journals (Sweden)

    Jia-Shuin Lin

    2016-11-01

    Full Text Available This work aims to clarify the effect of magnetic graphene oxide (GO reorientation in a polymer matrix on the ionic conduction and methanol barrier properties of nanocomposite membrane electrolytes. Magnetic iron oxide (Fe3O4 nanoparticles were prepared and dispersed on GO nanosheets (GO-Fe3O4. The magnetic GO-Fe3O4 was imbedded into a quaternized polyvinyl alcohol (QPVA matrix and crosslinked (CL- with glutaraldehyde (GA to obtain a polymeric nanocomposite. A magnetic field was applied in the through-plane direction during the drying and film formation steps. The CL-QPVA/GO-Fe3O4 nanocomposite membranes were doped with an alkali to obtain hydroxide-conducting electrolytes for direct methanol alkaline fuel cell (DMAFC applications. The magnetic field-reoriented CL-QPVA/GO-Fe3O4 electrolyte demonstrated higher conductivity and lower methanol permeability than the unoriented CL-QPVA/GO-Fe3O4 membrane or the CL-QPVA film. The reoriented CL-QPVA/GO-Fe3O4 nanocomposite was used as the electrolyte in a DMAFC and resulted in a maximum power density of 55.4 mW·cm−2 at 60 °C, which is 73.7% higher than that of the composite without the magnetic field treatment (31.9 mW·cm−2. In contrast, the DMAFC using the CL-QPVA electrolyte generated only 22.4 mW·cm−2. This research proved the surprising benefits of magnetic-field-assisted orientation of GO-Fe3O4 in facilitating the ion conduction of a polymeric electrolyte.

  14. Progressive freezing of interacting spins in isolated finite magnetic ensembles

    Science.gov (United States)

    Bhattacharya, Kakoli; Dupuis, Veronique; Le-Roy, Damien; Deb, Pritam

    2017-02-01

    Self-organization of magnetic nanoparticles into secondary nanostructures provides an innovative way for designing functional nanomaterials with novel properties, different from the constituent primary nanoparticles as well as their bulk counterparts. Collective magnetic properties of such complex closed packing of magnetic nanoparticles makes them more appealing than the individual magnetic nanoparticles in many technological applications. This work reports the collective magnetic behaviour of magnetic ensembles comprising of single domain Fe3O4 nanoparticles. The present work reveals that the ensemble formation is based on the re-orientation and attachment of the nanoparticles in an iso-oriented fashion at the mesoscale regime. Comprehensive dc magnetic measurements show the prevalence of strong interparticle interactions in the ensembles. Due to the close range organization of primary Fe3O4 nanoparticles in the ensemble, the spins of the individual nanoparticles interact through dipolar interactions as realized from remnant magnetization measurements. Signature of super spin glass like behaviour in the ensembles is observed in the memory studies carried out in field cooled conditions. Progressive freezing of spins in the ensembles is corroborated from the Vogel-Fulcher fit of the susceptibility data. Dynamic scaling of relaxation reasserted slow spin dynamics substantiating cluster spin glass like behaviour in the ensembles.

  15. QNS study of uniaxial molecular reorientation in solid t-cyanobutane

    International Nuclear Information System (INIS)

    Urban, S.; Nawrocik, W.

    1977-01-01

    The results of a quasielastic neutron scattering (QNS) investigation on a t-cyanobutane, (CH 3 ) 3 CCN, sample jn three solid phases are presented. It was found there is a fast uniaxial reorientation of the t-cyanobutane molecules in phase 1, characterized by correlation times of the order of several picoseconds and an activation barrier ΔE= (0.5 +- 0.2) kcal/mole. The lack of quasielastic broadening in the neutron spectra of lower-temperature phases implies that molecular rotation then is much slower or completely hindered. (author)

  16. Conoscopic observation of director reorientation during Poiseuille flow of a nematic liquid crystal

    Science.gov (United States)

    Holmes, C. J.; Cornford, S. L.; Sambles, J. R.

    2009-10-01

    Director reorientation under pressure driven (Poiseuille) flow is observed conoscopically for the liquid crystal 5CB aligned at an azimuthal angle of 45° to the direction of flow. A polyimide surface treatment (AL 1254) is used to promote planar homogeneous alignment and rubbed to produce an initial azimuthal alignment angle ϕ0. Conoscopic interference figure rotation is documented as a function of flow rate and compared to that produced from numerical models using Leslie-Ericksen-Parodi theory. Model and data show excellent agreement.

  17. Dynamic Isovector Reorientation of Deuteron as a Probe to Nuclear Symmetry Energy.

    Science.gov (United States)

    Ou, Li; Xiao, Zhigang; Yi, Han; Wang, Ning; Liu, Min; Tian, Junlong

    2015-11-20

    We present the calculations on a novel reorientation effect of deuteron attributed to isovector interaction in the nuclear field of heavy target nuclei. The correlation angle determined by the relative momentum vector of the proton and the neutron originating from the breakup deuteron, which is experimentally detectable, exhibits significant dependence on the isovector nuclear potential but is robust against the variation of the isoscaler sector. In terms of sensitivity and cleanness, the breakup reactions induced by the polarized deuteron beam at about 100 MeV/u provide a more stringent constraint to the symmetry energy at subsaturation densities.

  18. Reaction and reorientation of electronically excited H2(B)

    Energy Technology Data Exchange (ETDEWEB)

    Pibel, Charles David [Univ. of California, Berkeley, CA (United States)

    1992-09-01

    The room temperature rate (TR) constants for fluorescence quenching fluorescence of H2, HD, and D2 B 1Σ$+\\atop{u}$ by 4He were measured as a function of the initially excited rotational and vibrational level of the hydrogen molecule, and the RT rate constants for molecular angular momentum reorientation of H2, HD and D2 (B 1Σ$+\\atop{u}$. v'=0, J'=1, MJ=0) in collisions with He, Ne, Ar and H2(X 1Σ$+\\atop{g}$ ) were also measured. Vibrational state dependence of the quenching cross sections fits a vibrationally adiabatic model of the quenching process. From the vibrational state dependence of the quenching cross section, the barrier height for the quenching reaction is found to be 250±40 cm-1, and the difference in the H-H stretching frequencies between H2(B) and the H2-He complex at the barrier to reaction is 140±80 cm-1. The effective cross sections for angular momentum reorientation in collisions of H2, HD, D2 with He and Ne were found to be about 30 Å2 and were nearly the same for each isotope and with He and Ne as collision partners. Cross sections forreorientation of HD and D2 in collisions with Ar were 10.6±2.0 and 13.9±3.0 Å2, respectively. Reorientation of D2(B) in collisions with room temperature H2(X) occurs with a 7.6±3.4 Å2 cross section. Calculated cross sections using semiclassical and quantum close coupled methods give cross sections for reorientation of H2(B) and D2(B) in collisions with He that agree quantitatively with experiment. Discrepancy between the calculated and experimental cross sections for HD(B)-HE are likely due to rotational relaxation in HD a Turbo PASCAL version of the data-taking program is included.

  19. Reaction and reorientation of electronically excited H[sub 2](B)

    Energy Technology Data Exchange (ETDEWEB)

    Pibel, C.D.

    1992-09-01

    The room temperature rate (TR) constants for fluorescence quenching fluorescence of H[sub 2], HD, and D[sub 2] B [sup 1][Sigma][sub u][sup +] by [sup 4]He were measured as a function of the initially excited rotational and vibrational level of the hydrogen molecule, and the RT rate constants for molecular angular momentum reorientation of H[sub 2], HD and D[sub 2] (B [sup 1][Sigma][sub u][sup +]. v[prime]=0, J[prime]=1, M[sub J]=0) in collisions with He, Ne, Ar and H[sub 2](X [sup 1][Sigma][sub g][sup +]) were also measured. Vibrational state dependence of the quenching cross sections fits a vibrationally adiabatic model of the quenching process. From the vibrational state dependence of the quenching cross section, the barrier height for the quenching reaction is found to be 250[plus minus]40 cm[sup [minus]1], and the difference in the H-H stretching frequencies between H[sub 2](B) and the H[sub 2]-He complex at the barrier to reaction is 140[plus minus]80 cm[sup [minus]1]. The effective cross sections for angular momentum reorientation in collisions of H[sub 2], HD, D[sub 2] with He and Ne were found to be about 30 [Angstrom][sup 2] and were nearly the same for each isotope and with He and Ne as collision partners. Cross sections forreorientation of HD and D[sub 2] in collisions with Ar were 10.6[plus minus]2.0 and 13.9[plus minus]3.0 [Angstrom][sup 2], respectively. Reorientation of D[sub 2](B) in collisions with room temperature H[sub 2](X) occurs with a 7.6[plus minus]3.4 [Angstrom][sup 2] cross section. Calculated cross sections using semiclassical and quantum close coupled methods give cross sections for reorientation of H[sub 2](B) and D[sub 2](B) in collisions with He that agree quantitatively with experiment. Discrepancy between the calculated and experimental cross sections for HD(B)-HE are likely due to rotational relaxation in HD a Turbo PASCAL version of the data-taking program is included.

  20. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

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

  1. Multiple spin-flop phase diagram of BaCu{sub 2}Si{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Glazkov, V N; Zheludev, A [Laboratorium fuer Festkoerperphysik, ETH Zurich, 8093 Zuerich (Switzerland); Dhalenne, G; Revcolevschi, A, E-mail: glazkov@kapitza.ras.ru [Laboratoire de Physico-Chimie de l' Etat Solide, Universite Paris-Sud, 91405 Orsay Cedex (France)

    2011-03-02

    The quasi-one-dimensional compound BaCu{sub 2}Si{sub 2}O{sub 7} demonstrates numerous spin-reorientation transitions both for a magnetic field applied along the easy axis of magnetization and a magnetic field applied perpendicular to it. The magnetic phase diagram for all three principal orientations is obtained by magnetization and specific heat measurements. Values of all critical fields and low-temperature values of magnetization jumps are determined for all transitions.

  2. Spin Hall effects in metallic antiferromagnets – perspectives for future spin-orbitronics

    Directory of Open Access Journals (Sweden)

    Joseph Sklenar

    2016-05-01

    Full Text Available We investigate angular dependent spin-orbit torques from the spin Hall effect in a metallic antiferromagnet using the spin-torque ferromagnetic resonance technique. The large spin Hall effect exists in PtMn, a prototypical CuAu-I-type metallic antiferromagnet. By applying epitaxial growth, we previously reported an appreciable difference in spin-orbit torques for c- and a-axis orientated samples, implying anisotropic effects in magnetically ordered materials. In this work we demonstrate through bipolar-magnetic-field experiments a small but noticeable asymmetric behavior in the spin-transfer-torque that appears as a hysteresis effect. We also suggest that metallic antiferromagnets may be good candidates for the investigation of various unidirectional effects related to novel spin-orbitronics phenomena.

  3. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    Science.gov (United States)

    Aleksandrova, Olga

    2015-04-01

    with different polarity. As shown by the spin labeling ESR experiment, molecules modeling SDZ were promptly bound to non-hydrolysable network of soil organic matter only via the aromatic amines that was accompanied by a prompt enlargement of humic particles binding aromatic amines, whereas binding of decomposition products of SDZ to humic acids of soil via the aliphatic amines was not observable. The ESR spectra obviously showed a single-phase process of covalent binding of the aromatic amines. Repeated washouts of labeled soil samples using distil water and ultrafiltration through the membrane of 5000 MWCO PES confirmed irreversible binding of the aromatic amines, and showed that via the aliphatic amines, binding of SDZ or decomposition products of SDZ to soil might also occur but reversibly and only to small soil molecules, which don't enter into the composition of non-hydrolysable part of soil organic matter. SL ESR experiments of different soils at the presence of Laccase highlighted that covalent binding of the aromatic amines to humic particles occurred in the specific hydrophobic areas of soil found as depleted in oxygen. All measured data evidenced that first, SDZ might be decomposed that allowed for measuring the same change of a paramagnetic signal of soil organic matter influenced by both aromatic and aliphatic amines as in the experiment of the interaction of soil with SDZ. Second, a decomposition product of SDZ with the aromatic amine might be bound to non-hydrolysable parts of soil organic matter under specific anaerobic conditions only via 1,4 - nucleophilic addition, Michael-type addition. Gulkowska, A., Thalmann, B., D., Hollender, J., & Krauss, M. (2014). Chemosphere, 107, 366 - 372. Müller, T., Rosendahl, I., Focks, A., Siemens, J., Klasmeier, J., & Matthies. (2013). Environmental Pollution, 172,180 - 185. Nowak, K.M., Miltner, A., Gehre, M., Schaeffer, A., & Kaestner, M. (2011). Environmental Science & Technology 45, 999 - 1006. Weber, E.J., Spidle

  4. Intragranular twinning, detwinning, and twinning-like lattice reorientation in magnesium alloys

    International Nuclear Information System (INIS)

    Wu, Wei; Gao, Yanfei; Li, Nan; Parish, Chad M.; Liu, Wenjun; Liaw, Peter K.; An, Ke

    2016-01-01

    Deformation twinning plays a critical role on improving metals or alloys ductility, especially for hexagonal close-packed materials with low symmetry crystal structure. A rolled Mg alloy was selected as a model system to investigate the extension twinning behaviors and characteristics of parent-twin interactions by nondestructive in situ 3D synchrotron X-ray microbeam diffraction. Besides twinning-detwinning process, the “twinning-like” lattice reorientation process was captured within an individual grain inside a bulk material during the strain reversal. The distributions of parent, twin, and reorientated grains and sub-micron level strain variation across the twin boundary are revealed. A theoretical calculation of the lattice strain confirms that the internal strain distribution in parent and twinned grains correlates with the experimental setup, grain orientation of parent, twin, and surrounding grains, as well as the strain path changes. The study suggests a novel deformation mechanism within the hexagonal close-packed structure that cannot be determined from surface-based characterization methods.

  5. Polarization Sensitive Measurements of Molecular Reorientation in a Glass Capacitor Cell

    Science.gov (United States)

    Cooper, Nathan; Lawhead, Carlos; Anderson, Josiah; Shiver, Tegan; Prayaga, Chandra; Ujj, Laszlo

    2014-03-01

    It is well known that molecules having a permanent dipole moment tend to orient in the direction of the electric field at room temperature. The reorientation can be probed with the help of linear spectroscopy methods such as fluorescence anisotropy measurements. We have used nonlinear polarization sensitive Raman scattering spectroscopy to quantify the orientation effect of the dipoles. Vibrational spectra of the molecules has been recorded as a function of the external electric field. The polarization changes observed during the measurement are directly linked to the molecular reorientation rearrangement. Spectra has been recorded with a laser spectrometer comprised of a Nd:YAG laser and an optical parametric oscillator and an imaging spectrometer with a CCD detector. In order to make this measurement we have constructed a glass capacitor cell coated in TiO and applied a significant electric field (0-3 kV/mm) to the sample. Our measurements showed that the orientation effect is most significant for liquid crystals as observed previously with non-polarization sensitive CARS spectroscopy.

  6. Reorientation-effect measurement of the first 2+ state in 12C: Confirmation of oblate deformation

    Science.gov (United States)

    Kumar Raju, M.; Orce, J. N.; Navrátil, P.; Ball, G. C.; Drake, T. E.; Triambak, S.; Hackman, G.; Pearson, C. J.; Abrahams, K. J.; Akakpo, E. H.; Al Falou, H.; Churchman, R.; Cross, D. S.; Djongolov, M. K.; Erasmus, N.; Finlay, P.; Garnsworthy, A. B.; Garrett, P. E.; Jenkins, D. G.; Kshetri, R.; Leach, K. G.; Masango, S.; Mavela, D. L.; Mehl, C. V.; Mokgolobotho, M. J.; Ngwetsheni, C.; O'Neill, G. G.; Rand, E. T.; Sjue, S. K. L.; Sumithrarachchi, C. S.; Svensson, C. E.; Tardiff, E. R.; Williams, S. J.; Wong, J.

    2018-02-01

    A Coulomb-excitation reorientation-effect measurement using the TIGRESS γ-ray spectrometer at the TRIUMF/ISAC II facility has permitted the determination of the 〈 21+ ‖ E 2 ˆ ‖21+ 〉 diagonal matrix element in 12C from particle-γ coincidence data and state-of-the-art no-core shell model calculations of the nuclear polarizability. The nuclear polarizability for the ground and first-excited (21+) states in 12C have been calculated using chiral NN N4LO500 and NN+3NF350 interactions, which show convergence and agreement with photo-absorption cross-section data. Predictions show a change in the nuclear polarizability with a substantial increase between the ground state and first excited 21+ state at 4.439 MeV. The polarizability of the 21+ state is introduced into the current and previous Coulomb-excitation reorientation-effect analyses of 12C. Spectroscopic quadrupole moments of QS (21+) = + 0.053 (44) eb and QS (21+) = + 0.08 (3) eb are determined, respectively, yielding a weighted average of QS (21+) = + 0.071 (25) eb, in agreement with recent ab initio calculations. The present measurement confirms that the 21+ state of 12C is oblate and emphasizes the important role played by the nuclear polarizability in Coulomb-excitation studies of light nuclei.

  7. Target berthing and base reorientation of free-floating space robotic system after capturing

    Science.gov (United States)

    Xu, Wenfu; Li, Cheng; Liang, Bin; Xu, Yangsheng; Liu, Yu; Qiang, Wenyi

    2009-01-01

    Space robots are playing an increasingly important role in on-orbital servicing, including repairing, refueling, or de-orbiting the satellite. The target must be captured and berthed before the servicing task starts. However, the attitude of the base may lean much and needs re-orientating after capturing. In this paper, a method is proposed to berth the target, and re-orientate the base at the same time, using manipulator motion only. Firstly, the system state is formed of the attitude quaternion and joint variables, and the joint paths are parameterized by sinusoidal functions. Then, the trajectory planning is transformed to an optimization problem. The cost function, defined according to the accuracy requirements of system variables, is the function of the parameters to be determined. Finally, we solve the parameters using the particle swarm optimization algorithm. Two typical cases of the spacecraft with a 6-DOF manipulator are dynamically simulated, one is that the variation of base attitude is limited; the other is that both the base attitude and the joint rates are constrained. The simulation results verify the presented method.

  8. Light-induced electric field generated by photovoltaic substrates investigated through liquid crystal reorientation

    Science.gov (United States)

    Lucchetti, L.; Kushnir, K.; Reshetnyak, V.; Ciciulla, F.; Zaltron, A.; Sada, C.; Simoni, F.

    2017-11-01

    Liquid crystal reorientation is exploited to analyze the electric field generated by light irradiation in iron-doped lithium niobate crystals. The evaluation of the strength of this light-induced field is based on the measurement of the phase shift induced in a probe light beam by a liquid crystal cell built with two z-cut iron-doped lithium niobate crystals as substrates. Then, the field profile has been determined starting from a Gaussian-like surface charge density following the model described in the text. The director profile corresponding to the modelled electric field is in good agreement with the director reorientation evaluated experimentally by means of the light-induced phase shift. This investigation gives a new approach to study the effects based on the photovoltaic response of lithium niobate crystals. Moreover, the characterization of the electric field optically generated inside the LC layer is highly desirable in view of the realization of new all-optical devices to be integrated in optofluidic platforms.

  9. Reorienting a paediatric oral health service towards prevention: lessons from a qualitative study of dental professionals.

    Science.gov (United States)

    Cashmore, Aaron W; Noller, Jennifer; Ritchie, Jan; Johnson, Bronwyn; Blinkhorn, Anthony S

    2011-04-01

    Reorienting primary care dental services towards prevention is a priority for improving the oral health of Australian children with extensive dental caries. We explored the attitudes and beliefs of dental staff about the factors that helped or hindered the establishment and implementation of a hospital-based parent counselling program to manage existing, and prevent new, carious lesions in children. A further aim was to explore the influence of the program on the hospital's reorientation to prevention. Eight of nine program staff participated in two focus group interviews, and two co-ordinating staff participated in semi-structured interviews. Interviews were audio-recorded and transcribed. Interview recordings and transcripts were analysed by qualitative thematic analysis. The participants identified a number of factors that they felt influenced the establishment and implementation of the program, including the dental team's support of the initiative, the advantages of building on existing clinic infrastructure and procedures, the utility of harnessing dental assistants as a resource for oral health promotion, and the confidence of dental professionals to provide parent counselling. Efforts to establish a preventive program in a public paediatric dental service should ensure that all members of the dental team are engaged during all phases of the program, that dental assistants are trained and supported to deliver parent counselling, and that interprofessional partnerships with services such as dietetics are fostered.

  10. Decoherence dynamics of a single spin versus spin ensemble

    NARCIS (Netherlands)

    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

  11. Large spin relaxation anisotropy and valley-Zeeman spin-orbit coupling in WSe2/graphene/h -BN heterostructures

    Science.gov (United States)

    Zihlmann, Simon; Cummings, Aron W.; Garcia, Jose H.; Kedves, Máté; Watanabe, Kenji; Taniguchi, Takashi; Schönenberger, Christian; Makk, Péter

    2018-02-01

    Large spin-orbital proximity effects have been predicted in graphene interfaced with a transition-metal dichalcogenide layer. Whereas clear evidence for an enhanced spin-orbit coupling has been found at large carrier densities, the type of spin-orbit coupling and its relaxation mechanism remained unknown. We show an increased spin-orbit coupling close to the charge neutrality point in graphene, where topological states are expected to appear. Single-layer graphene encapsulated between the transition-metal dichalcogenide WSe2 and h -BN is found to exhibit exceptional quality with mobilities as high as 1 ×105 cm2 V-1 s-1. At the same time clear weak antilocalization indicates strong spin-orbit coupling, and a large spin relaxation anisotropy due to the presence of a dominating symmetric spin-orbit coupling is found. Doping-dependent measurements show that the spin relaxation of the in-plane spins is largely dominated by a valley-Zeeman spin-orbit coupling and that the intrinsic spin-orbit coupling plays a minor role in spin relaxation. The strong spin-valley coupling opens new possibilities in exploring spin and valley degree of freedom in graphene with the realization of new concepts in spin manipulation.

  12. Spin-polarized spin excitation spectroscopy

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  13. Magnons, Spin Current and Spin Seebeck Effect

    Science.gov (United States)

    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).

  14. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2014-05-28

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  15. Spin-transfer torque generated by a topological insulator

    KAUST Repository

    Mellnik, A. R.

    2014-07-23

    Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. There has been considerable recent progress in this effort; in particular, it has been discovered that spin-orbit interactions in heavy-metal/ferromagnet bilayers can produce strong current-driven torques on the magnetic layer, via the spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the ferromagnet. In the search for materials to provide even more efficient spin-orbit-induced torques, some proposals have suggested topological insulators, which possess a surface state in which the effects of spin-orbit coupling are maximal in the sense that an electron\\' s spin orientation is fixed relative to its propagation direction. Here we report experiments showing that charge current flowing in-plane in a thin film of the topological insulator bismuth selenide (Bi2Se3) at room temperature can indeed exert a strong spin-transfer torque on an adjacent ferromagnetic permalloy (Ni81Fe19) thin film, with a direction consistent with that expected from the topological surface state. We find that the strength of the torque per unit charge current density in Bi 2Se3 is greater than for any source of spin-transfer torque measured so far, even for non-ideal topological insulator films in which the surface states coexist with bulk conduction. Our data suggest that topological insulators could enable very efficient electrical manipulation of magnetic materials at room temperature, for memory and logic applications. © 2014 Macmillan Publishers Limited. All rights reserved.

  16. Tunnelling reorientation of the V- and Vsub(Li) centers in MgO at liquid helium temperatures

    International Nuclear Information System (INIS)

    Rius, G.; Herve, A.; Picard, R.; Santier, C.

    1972-01-01

    E.P.R. under uniaxial stress, E.P.R. in an electric field and ELDOR experiments show that the V - and Vsub(lithium) trapped hole centres in MgO reorientate at liquid-helium temperatures. The elastic and electric dipole moments of the V - centre were measured at 77K. The temperature variation of the reorientation time of the V - centre, 25+-5ms at 4.2K and 60+-10ms at 2.1K, shows that the orientation process is a one phonon assisted tunnelling process [fr

  17. Renal SPECT with {sup 99m} Tc-Dmsa. Reorientation and processing; SPECT renal con {sup 99m} Tc-Dmsa. Reorientacion y procesamiento

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.L.; Perera, A.; Fraxedas, R. [Centro de InvestigacionesClinicas 34 no.4501 e/45 y 47 Kohly, Playa C. Habana (Cuba)

    1998-12-31

    For the study of different renal affections with repercussion in the parenchyma is widely used the plane gammagraphy wit {sup 99m} Tc-Dmsa though not in the same way the SPECT technique. In general, the different inclination and orientation of the longitudinal axes of both kidneys in the patients entail aid to high variability in the detection of the different types of defects which leads to a possible mistaken diagnostic. With a view to this,it was developed in our centre a methodology for the automated reorientation of the different renal volumes obtained by SPECT and its posterior processing, obtaining as result a software with a high grade of independence from the operator. In this way, it is obtained a procedure standardization and so it let us with major rigor to realize evolutive studies of the patients. (Author)

  18. Perovskite-Type InCoO3 with Low-Spin Co3+: Effect of In-O Covalency on Structural Stabilization in Comparison with Rare-Earth Series.

    Science.gov (United States)

    Fujita, Koji; Kawamoto, Takahiro; Yamada, Ikuya; Hernandez, Olivier; Akamatsu, Hirofumi; Kumagai, Yu; Oba, Fumiyasu; Manuel, Pascal; Fujikawa, Ryo; Yoshida, Suguru; Fukuda, Masayuki; Tanaka, Katsuhisa

    2017-09-18

    Perovskite rare-earth cobaltites ACoO 3 (A = Sc, Y, La-Lu) have been of enduring interest for decades due to their unusual structural and physical properties associated with the spin-state transitions of low-spin Co 3+ ions. Herein, we have synthesized a non-rare-earth perovskite cobaltite, InCoO 3 , at 15 GPa and 1400 °C and investigated its crystal structure and magnetic ground state. Under the same high-pressure and high-temperature conditions, we also prepared a perovskite-type ScCoO 3 with an improved cation stoichiometry in comparison to that in a previous study, where synthesis at 6 GPa and 1297 °C yielded a perovskite cobaltite with cation mixing on the A-site, (Sc 0.95 Co 0.05 )CoO 3 . The two perovskite phases have nearly stoichiometric cation compositions, crystallizing in the orthorhombic Pnma space group. In the present investigation, comprehensive studies on newly developed and well-known Pnma ACoO 3 perovskites (A = In, Sc, Y, Pr-Lu) show that InCoO 3 does not fulfill the general evolution of crystal metrics with A-site cation size, indicating that InCoO 3 and rare-earth counterparts have different chemistry for stabilizing the Pnma structures. Detailed structural analyses combined with first-principles calculations reveal that the origin of the anomaly for InCoO 3 is ascribed to the A-site cation displacements that accompany octahedral tilts; despite the highly tilted CoO 6 network, the In-O covalency makes In 3+ ions reluctant to move from their ideal cubic-symmetry position, leading to less orthorhombic distortion than would be expected from electrostatic/ionic size mismatch effects. Magnetic studies demonstrate that InCoO 3 and ScCoO 3 are diamagnetic with a low-spin state of Co 3+ below 300 K, in contrast to the case of (Sc 0.95 Co 0.05 )CoO 3 , where the high-spin Co 3+ ions on the A-site generate a large paramagnetic moment. The present work extends the accessible composition range of the low-spin orthocobaltite series and thus should help

  19. Spin-Mechatronics

    Science.gov (United States)

    Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

    2017-01-01

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

  20. A geometrical approach to determine reorientation start and continuation conditions in ferromagnetic shape memory alloys considering the effects of loading history

    International Nuclear Information System (INIS)

    Shirani, M; Kadkhodaei, M

    2014-01-01

    Ferromagnetic shape memory alloys (FSMAs) and magnetic shape memory alloys (MSMAs) are metallic alloys that can undergo inelastic responses when exposed to magnetic fields. Several constitutive models have been proposed so far to model the behaviors of FSMAs. In this work, the effects of loading history on reorientation start conditions are considered, and it is shown that reorientation start conditions are not fixed values; rather, they change with respect to the amount of loading history. To consider the effects of loading history on reorientation start conditions, an available phase diagram in stress-field space is generalized to reorientation surfaces in stress-field-loading history space. Correspondingly, kinetic laws are derived in a continuum framework to be used with the reorientation surfaces to determine the amount of the martensitic variant 2 volume fraction. Based on the geometry of the reorientation surfaces, conditions that must be satisfied to ensure the continuation of reorientations are obtained. Available experimental findings validate the proposed model and the reorientation surfaces. (paper)

  1. Two-dimensional spin diffusion in multiterminal lateral spin valves

    Science.gov (United States)

    Saha, D.; Basu, D.; Holub, M.; Bhattacharya, P.

    2008-01-01

    The effects of two-dimensional spin diffusion on spin extraction in lateral semiconductor spin valves have been investigated experimentally and theoretically. A ferromagnetic collector terminal of variable size is placed between the ferromagnetic electron spin injector and detector of a conventional lateral spin valve for spin extraction. It is observed that transverse spin diffusion beneath the collector terminal plays an important role along with the conventional longitudinal spin diffusion in describing the overall transport of spin carriers. Two-dimensional spin diffusion reduces the perturbation of the channel electrochemical potentials and improves spin extraction.

  2. Communication: On the origin of the non-Arrhenius behavior in water reorientation dynamics.

    Science.gov (United States)

    Stirnemann, Guillaume; Laage, Damien

    2012-07-21

    We combine molecular dynamics simulations and analytic modeling to determine the origin of the non-Arrhenius temperature dependence of liquid water's reorientation and hydrogen-bond dynamics between 235 K and 350 K. We present a quantitative model connecting hydrogen-bond exchange dynamics to local structural fluctuations, measured by the asphericity of Voronoi cells associated with each water molecule. For a fixed local structure the regular Arrhenius behavior is recovered, and the global anomalous temperature dependence is demonstrated to essentially result from a continuous shift in the unimodal structure distribution upon cooling. The non-Arrhenius behavior can thus be explained without invoking an equilibrium between distinct structures. In addition, the large width of the homogeneous structural distribution is shown to cause a growing dynamical heterogeneity and a non-exponential relaxation at low temperature.

  3. Generalized reorientation cross sections. II. Scattering frame transformations and propensity rules

    International Nuclear Information System (INIS)

    The generalized molecular reorientation cross sections derived in the first paper of this series are reformulated using an unsophisticated version of the internal angular momentum coupling scheme introduced by the Wisconsin school. In particular, we consider the transformation from quantization axes that diagonalize the wave amplitude in the magnetic rotational angular momentum indices to space-fixed quantization axes in either the center of mass or laboratory frames. The reformulated coupling scheme makes it apparent that these transformations bias the cross sections toward orientation conserving propensity rules. This is advanced as the reason why the self-same, close-coupled calculations have been used to support orientation and j/sub z/ conserving propensity rules

  4. Using Personification and Agency Reorientation to Reduce Mental-Health Clinicians’ Stigmatizing Attitudes Toward Patients

    Science.gov (United States)

    Lebowitz, Matthew S.; Ahn, Woo-kyoung

    2015-01-01

    People with mental disorders are strongly stigmatized. Among mental-health professionals, stigmatizing attitudes often manifest as desire for social distance from people with mental disorders. Currently ascendant biomedical conceptualizations of psychopathology could exacerbate this problem by engendering dehumanization, which is linked to prejudice. Given the clinical implications of such an occurrence, the present research tested a possible mitigation strategy. In an online study of 216 U.S. mental-health clinicians, two strategies for mitigating dehumanization in healthcare were tested—personification, highlighting personal traits of people with mental disorders rather than presenting them as malfunctioning brains, and agency reorientation, underscoring people’s ability to make choices and decisions. This approach yielded significantly less desire for social distance, among clinicians, from a person with depression whose symptoms were explained biologically. These findings may suggest an avenue for decreasing stigma in clinical practice. PMID:27766309

  5. Solid triphenylmethanol: A molecular material that undergoes multiple internal reorientational processes on different timescales

    International Nuclear Information System (INIS)

    Kitchin, Simon J.; Xu Mingcan; Serrano-Gonzalez, Heliodoro; Coates, Laura J.; Zaka Ahmed, S.; Glidewell, Christopher; Harris, Kenneth D.M.

    2006-01-01

    In solid triphenylmethanol, the molecules are arranged in hydrogen-bonded tetramers, and it is already well established that the hydrogen bonding in this material undergoes a dynamic switching process between different hydrogen bonding arrangements. In addition to this motion, we show here, from solid-state 2 H NMR studies of the deuterated material (C 6 D 5 ) 3 COH, that each phenyl ring in this material undergoes a 180 deg.-jump reorientation about the C 6 D 5 -C(OH) bond, with an activation energy of ca. 50 kJ mol -1 . The timescale for the phenyl ring dynamics is several orders of magnitude longer than the timescale for the hydrogen bond dynamics in this material, and is uncorrelated with the dynamics of the hydrogen bonding arrangement

  6. Subsidies to energy in the world: their extent, their efficiency and their necessary reorientation

    International Nuclear Information System (INIS)

    Finon, D.

    2010-10-01

    This report aims at analyzing the extent of subsidies to energy in the world, at assessing theoretical and practical arguments against different forms of subsidy, and at synthesizing reflections on reforms of subsidies to energy, mainly in developing countries. In the first part, the author recalls the theoretical and practical backgrounds of subsidies to energy, indicates the different forms of support to energy production and consumption, and discusses the existing assessments in the world and in some regions while specifying subsidies to fuels in the transport sector. In a second part, he addresses theoretical and practical critics of subsidies (notably in terms of environmental and economical inefficiency), assessments of economical and environmental benefits of their withdrawal, and ways of reorienting subsidies for fossil fuels in developing countries

  7. Spacecraft reorientation control in presence of attitude constraint considering input saturation and stochastic disturbance

    Science.gov (United States)

    Cheng, Yu; Ye, Dong; Sun, Zhaowei; Zhang, Shijie

    2018-03-01

    This paper proposes a novel feedback control law for spacecraft to deal with attitude constraint, input saturation, and stochastic disturbance during the attitude reorientation maneuver process. Applying the parameter selection method to improving the existence conditions for the repulsive potential function, the universality of the potential-function-based algorithm is enhanced. Moreover, utilizing the auxiliary system driven by the difference between saturated torque and command torque, a backstepping control law, which satisfies the input saturation constraint and guarantees the spacecraft stability, is presented. Unlike some methods that passively rely on the inherent characteristic of the existing controller to stabilize the adverse effects of external stochastic disturbance, this paper puts forward a nonlinear disturbance observer to compensate the disturbance in real-time, which achieves a better performance of robustness. The simulation results validate the effectiveness, reliability, and universality of the proposed control law.

  8. Nonlinear continuous-wave optical propagation in nematic liquid crystals: Interplay between reorientational and thermal effects.

    Science.gov (United States)

    Alberucci, Alessandro; Laudyn, Urszula A; Piccardi, Armando; Kwasny, Michał; Klus, Bartlomiej; Karpierz, Mirosław A; Assanto, Gaetano

    2017-07-01

    We investigate nonlinear optical propagation of continuous-wave (CW) beams in bulk nematic liquid crystals. We thoroughly analyze the competing roles of reorientational and thermal nonlinearity with reference to self-focusing/defocusing and, eventually, the formation of nonlinear diffraction-free wavepackets, the so-called spatial optical solitons. To this extent we refer to dye-doped nematic liquid crystals in planar cells excited by a single CW beam in the highly nonlocal limit. To adjust the relative weight between the two nonlinear responses, we employ two distinct wavelengths, inside and outside the absorption band of the dye, respectively. Different concentrations of the dye are considered in order to enhance the thermal effect. The theoretical analysis is complemented by numerical simulations in the highly nonlocal approximation based on a semi-analytic approach. Theoretical results are finally compared to experimental results in the Nematic Liquid Crystals (NLC) 4-trans-4'-n-hexylcyclohexylisothiocyanatobenzene (6CHBT) doped with Sudan Blue dye.

  9. Cyclic stretch induces cell reorientation on substrates by destabilizing catch bonds in focal adhesions.

    Directory of Open Access Journals (Sweden)

    Bin Chen

    Full Text Available A minimal model of cellular mechanosensing system that consists of a single stress fiber adhering on a substrate via two focal adhesions made of catch bonds is adopted to investigate the phenomena of cell reorientation on substrates induced by an applied uniaxial cyclic stretch. The model indicates that the catch bonds in the focal adhesions experience a periodically oscillating internal force with amplitude and frequency controlled by two intrinsic clocks of the stress fiber, one associated with localized activation and the other with homogeneous activation of sarcomere units along the stress fiber. It is shown that this oscillating force due to cyclic stretch tends to destabilize focal adhesions by reducing the lifetime of catch bonds. The resulting slide or relocation of focal adhesions then causes the associated stress fiber to shorten and rotate to configurations nearly perpendicular to the stretching direction. These predicted behaviors from our model are consistent with a wide range of experimental observations.

  10. Studying Dynamic Myofiber Aggregate Reorientation in Dilated Cardiomyopathy Using In Vivo Magnetic Resonance Diffusion Tensor Imaging.

    Science.gov (United States)

    von Deuster, Constantin; Sammut, Eva; Asner, Liya; Nordsletten, David; Lamata, Pablo; Stoeck, Christian T; Kozerke, Sebastian; Razavi, Reza

    2016-10-01

    The objective of this study is to assess the dynamic alterations of myocardial microstructure and strain between diastole and systole in patients with dilated cardiomyopathy relative to healthy controls using the magnetic resonance diffusion tensor imaging, myocardial tagging, and biomechanical modeling. Dual heart-phase diffusion tensor imaging was successfully performed in 9 patients and 9 controls. Tagging data were acquired for the diffusion tensor strain correction and cardiac motion analysis. Mean diffusivity, fractional anisotropy, and myocyte aggregate orientations were compared between both cohorts. Cardiac function was assessed by left ventricular ejection fraction, torsion, and strain. Computational modeling was used to study the impact of cardiac shape on fiber reorientation and how fiber orientations affect strain. In patients with dilated cardiomyopathy, a more longitudinal orientation of diastolic myofiber aggregates was measured compared with controls. Although a significant steepening of helix angles (HAs) during contraction was found in the controls, consistent change in HAs during contraction was absent in patients. Left ventricular ejection fraction, cardiac torsion, and strain were significantly lower in the patients compared with controls. Computational modeling revealed that the dilated heart results in reduced HA changes compared with a normal heart. Reduced torsion was found to be exacerbated by steeper HAs. Diffusion tensor imaging revealed reduced reorientation of myofiber aggregates during cardiac contraction in patients with dilated cardiomyopathy relative to controls. Left ventricular remodeling seems to be an important factor in the changes to myocyte orientation. Steeper HAs are coupled with a worsening in strain and torsion. Overall, the findings provide new insights into the structural alterations in patients with dilated cardiomyopathy. © 2016 The Authors.

  11. Re-orienting a remote acute care model towards a primary health care approach: key enablers.

    Science.gov (United States)

    Carroll, Vicki; Reeve, Carole A; Humphreys, John S; Wakerman, John; Carter, Maureen

    2015-01-01

    The objective of this study was to identify the key enablers of change in re-orienting a remote acute care model to comprehensive primary healthcare delivery. The setting of the study was a 12-bed hospital in Fitzroy Crossing, Western Australia. Individual key informant, in-depth interviews were completed with five of six identified senior leaders involved in the development of the Fitzroy Valley Health Partnership. Interviews were recorded and transcripts were thematically analysed by two investigators for shared views about the enabling factors strengthening primary healthcare delivery in a remote region of Australia. Participants described theestablishment of a culturally relevant primary healthcare service, using a community-driven, 'bottom up' approach characterised by extensive community participation. The formal partnership across the government and community controlled health services was essential, both to enable change to occur and to provide sustainability in the longer term. A hierarchy of major themes emerged. These included community participation, community readiness and desire for self-determination; linkages in the form of a government community controlled health service partnership; leadership; adequate infrastructure; enhanced workforce supply; supportive policy; and primary healthcare funding. The strong united leadership shown by the community and the health service enabled barriers to be overcome and it maximised the opportunities provided by government policy changes. The concurrent alignment around a common vision enabled implementation of change. The key principle learnt from this study is the importance of community and health service relationships and local leadership around a shared vision for the re-orientation of community health services.

  12. Practicalities and challenges in re-orienting the health system in Zambia for treating chronic conditions.

    Science.gov (United States)

    Aantjes, Carolien J; Quinlan, Tim K C; Bunders, Joske F G

    2014-07-08

    The rapid evolution in disease burdens in low- and middle income countries is forcing policy makers to re-orient their health system towards a system which has the capability to simultaneously address infectious and non-communicable diseases. This paper draws on two different but overlapping studies which examined how actors in the Zambian health system are re-directing their policies, strategies and service structures to include the provision of health care for people with chronic conditions. Study methods in both studies included semi-structured interviews with government health officials at national level, and governmental and non-governmental health practitioners operating from community-, primary health care to hospital facility level. Focus group discussions were conducted with staff, stakeholders and caregivers of programmes providing care and support at community- and household levels. Study settings included urban and rural sites. A series of adaptations transformed the HIV programme from an emergency response into the first large chronic care programme in the country. There are clear indications that the Zambian government is intending to expand this reach to patients with non-communicable diseases. Challenges to do this effectively include a lack of proper NCD prevalence data for planning, a concentration of technology and skills to detect and treat NCDs at secondary and tertiary levels in the health system and limited interest by donor agencies to support this transition. The reorientation of Zambia's health system is in full swing and uses the foundation of a decentralised health system and presence of local models for HIV chronic care which actively involve community partners, patients and their families. There are early warning signs which could cause this transition to stall, one of which is the financial capability to resource this process.

  13. 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.

  14. The impact of reorienting cone-beam computed tomographic images in varied head positions on the coordinates of anatomical landmarks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Hun; Jeong, Ho Gul; Hwang, Jae Joon; Lee, Jung Hee; Han, Sang Sun [Dept. of Oral and Maxillofacial Radiology, Yonsei University, College of Dentistry, Seoul (Korea, Republic of)

    2016-06-15

    The aim of this study was to compare the coordinates of anatomical landmarks on cone-beam computed tomographic (CBCT) images in varied head positions before and after reorientation using image analysis software. CBCT images were taken in a normal position and four varied head positions using a dry skull marked with 3 points where gutta percha was fixed. In each of the five radiographic images, reference points were set, 20 anatomical landmarks were identified, and each set of coordinates was calculated. Coordinates in the images from the normally positioned head were compared with those in the images obtained from varied head positions using statistical methods. Post-reorientation coordinates calculated using a three-dimensional image analysis program were also compared to the reference coordinates. In the original images, statistically significant differences were found between coordinates in the normal-position and varied-position images. However, post-reorientation, no statistically significant differences were found between coordinates in the normal-position and varied-position images. The changes in head position impacted the coordinates of the anatomical landmarks in three-dimensional images. However, reorientation using image analysis software allowed accurate superimposition onto the reference positions.

  15. Stress-induced martensite variant reorientation in magnetic shape memory Ni–Mn–Ga single crystal studied by neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Molnár, Peter; Šittner, Petr; Lukáš, Petr; Hannula, S.-P.; Heczko, Oleg

    2008-01-01

    Roč. 17, č. 3 (2008), 035014/1-035014/4 ISSN 0964-1726 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10480505 Keywords : NiMnGa single crystal * neutron diffraction * stress induced martensite reorientation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.743, year: 2008

  16. Flux line lattice reorientation in the borocarbide superconductors with ¤H¤ parallel to ¤a¤

    DEFF Research Database (Denmark)

    Eskildsen, M.R.; Abrahamsen, A.B.; Lopez, D.

    2001-01-01

    Small angle neutron scattering studies of the flux line lattice in LuNi2B2C and ErNi2B2C induced by a held parallel to the a axis reveal a first order flux Line lattice reorientation transition. Below the transition the Bur line lattice nearest neighbor direction is parallel to the b axis...

  17. Interface-specific reorientation of embedded tetragonal ZrO{sub 2} particles in Ni{sub 1-x}O polycrystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.-Y. [Institute of Materials Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Shen Pouyan [Institute of Materials Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan (China)]. E-mail: pshen@mail.nsysu.edu.tw

    2005-05-25

    ZrO{sub 2}/Ni{sub 1-x}O (1:9 in molar ratio) composites were sintered and then annealed at 1650deg. C for 24 and 100h in air to study Ni{sub 1-x}O surface-controlled reorientation of the tetragonal (t-) ZrO{sub 2} particles, which transformed into monoclinic (m-) twin variants upon cooling. Transmission electron microscopy indicated that the ZrO{sub 2} particles fell into three topotaxial relationships with respect to the host Ni{sub 1-x}O grains: (1) parallel topotaxy (2) ''eutectic'' topotaxy, i.e. [100]{sub Z}//[111]{sub N}, [010]{sub Z}//[01-bar 1]{sub N} and (3) ''occasional'' topotaxy [100]{sub Z}//[111]{sub N}, [011-bar ]{sub Z}//[01-bar 1]{sub N}. The parallel topotaxy has a beneficial low energy for the family of {l_brace}100{r_brace}{sub Z,N} and {l_brace}111{r_brace}{sub Z,N} interfaces. The change from the occasional topotaxy to an energetically more favorable eutectic topotaxy was likely achieved by a rotation of the ZrO{sub 2} particles over a specific (100){sub Z}/(111){sub N} interface. Brownian-type rotation is probable for the embedded t-ZrO{sub 2} particles in terms of anchorage release at the interphase interface with the Ni{sub 1-x}O host. Detachment or bypassing of grain boundaries could also cause reorientation and shape change of intergranular ZrO{sub 2} particles.

  18. Spin at Lausanne

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    From 25 September to 1 October, some 150 spin enthusiasts gathered in Lausanne for the 1980 International Symposium on High Energy Physics with Polarized Beams and Polarized Targets. The programme was densely packed, covering physics interests with spin as well as the accelerator and target techniques which make spin physics possible

  19. Spin-torque transistor

    NARCIS (Netherlands)

    Bauer, G.E.W.; Brataas, A.; Tserkovnyak, Y.; Van Wees, B.J.

    2003-01-01

    A magnetoelectronic thin-film transistor is proposed that can display negative differential resistance and gain. The working principle is the modulation of the soure–drain current in a spin valve by the magnetization of a third electrode, which is rotated by the spin-torque created by a control spin

  20. Phase transitions and thermal entanglement of the distorted Ising-Heisenberg spin chain: topology of multiple-spin exchange interactions in spin ladders

    Science.gov (United States)

    Arian Zad, Hamid; Ananikian, Nerses

    2017-11-01

    We consider a symmetric spin-1/2 Ising-XXZ double sawtooth spin ladder obtained from distorting a spin chain, with the XXZ interaction between the interstitial Heisenberg dimers (which are connected to the spins based on the legs via an Ising-type interaction), the Ising coupling between nearest-neighbor spins of the legs and rungs spins, respectively, and additional cyclic four-spin exchange (ring exchange) in the square plaquette of each block. The presented analysis supplemented by results of the exact solution of the model with infinite periodic boundary implies a rich ground state phase diagram. As well as the quantum phase transitions, the characteristics of some of the thermodynamic parameters such as heat capacity, magnetization and magnetic susceptibility are investigated. We prove here that among the considered thermodynamic and thermal parameters, solely heat capacity is sensitive versus the changes of the cyclic four-spin exchange interaction. By using the heat capacity function, we obtain a singularity relation between the cyclic four-spin exchange interaction and the exchange coupling between pair spins on each rung of the spin ladder. All thermal and thermodynamic quantities under consideration should be investigated by regarding those points which satisfy the singularity relation. The thermal entanglement within the Heisenberg spin dimers is investigated by using the concurrence, which is calculated from a relevant reduced density operator in the thermodynamic limit.

  1. A new biomarker to examine the role of hippocampal function in the development of spatial reorientation in children: a review.

    Science.gov (United States)

    Vieites, Vanessa; Nazareth, Alina; Reeb-Sutherland, Bethany C; Pruden, Shannon M

    2015-01-01

    Spatial navigation is an adaptive skill that involves determining the route to a particular goal or location, and then traveling that path. A major component of spatial navigation is spatial reorientation, or the ability to reestablish a sense of direction after being disoriented. The hippocampus is known to be critical for navigating, and has more recently been implicated in reorienting in adults, but relatively little is known about the development of the hippocampus in relation to these large-scale spatial abilities in children. It has been established that, compared to school-aged children, preschool children tend to perform poorly on certain spatial reorientation tasks, suggesting that their hippocampi may not be mature enough to process the demands of such a task. Currently, common techniques used to examine underlying brain activity, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), are not suitable for examining hippocampal development in young children. In the present paper, we argue instead for the use of eyeblink conditioning (EBC), a relatively under-utilized, inexpensive, and safe method that is easy to implement in developing populations. In addition, EBC has a well defined neural circuitry, which includes the hippocampus, making it an ideal tool to indirectly measure hippocampal functioning in young children. In this review, we will evaluate the literature on EBC and its relation to hippocampal development, and discuss the possibility of using EBC as an objective measure of associative learning in relation to large-scale spatial skills. We support the use of EBC as a way to indirectly access hippocampal function in typical and atypical populations in order to characterize the neural substrates associated with the development of spatial reorientation abilities in early childhood. As such, EBC is a potential, simple biomarker for success in tasks that require the hippocampus, including spatial reorientation.

  2. A New Biomarker to Examine the Role of Hippocampal Function in the Development of Spatial Reorientation in Children: A Review

    Directory of Open Access Journals (Sweden)

    Vanessa eVieites

    2015-04-01

    Full Text Available Spatial navigation is an adaptive skill that involves determining the route to a particular goal or location, and then travelling that path. A major component of spatial navigation is spatial reorientation, or the ability to reestablish a sense of direction after being disoriented. The hippocampus is known to be critical for navigating, and has more recently been implicated in reorienting in adults, but relatively little is known about the development of the hippocampus in relation to these large-scale spatial abilities in children. It has been established that, compared to school-aged children, preschool children tend to perform poorly on certain spatial reorientation tasks, suggesting that their hippocampi may not be mature enough to process the demands of such a task. Currently, common techniques used to examine underlying brain activity, such as electroencephalography (EEG and functional magnetic resonance imaging (fMRI, are not suitable for examining hippocampal development in young children. In the present paper, we argue for the use of eyeblink conditioning (EBC, a relatively under-utilized, inexpensive, and safe method that is easy to implement in developing populations. In addition, EBC has a well defined neural circuitry, which includes the hippocampus, making it an ideal tool to indirectly measure hippocampal functioning in young children. In this review, we will evaluate the literature on EBC and its relation to hippocampal development, and discuss the possibility of using EBC as an objective measure of associative learning in relation to large-scale spatial skills. We support the use of EBC as a way to indirectly access hippocampal function in typical and atypical populations in order to characterize the neural substrates associated with the development of spatial reorientation abilities in early childhood. Thus, we advocate for EBC as a simple biomarker for success in various tasks that require the hippocampus, including spatial

  3. Utility of two types of MR cisternography for patency evaluation of aqueduct and third ventriculostomy site: Three dimentsional sagittal fast spin echo sequence and steady-state coherent fast gradient echo sequence

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Hyun; Kim, Eun Hee; Park, Jong Bin; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheol Kyu; Bae, Yun Jung; Lee, Kyung Mi [Dept. of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2015-07-15

    We aimed to evaluate the utility of two types of MR cisternography [fast spin echo sequence and steady-state coherent gradient echo (GRE) sequence] in addition to phase contrast-cine imaging (PC-cine), for assessing patency at the aqueduct and third ventriculostomy site. 43 patients (35 patients with suspected aqueductal stenosis and 8 patients with third ventriculostomy) were retrospectively analyzed. PC-cine, 3 dimensional sagittal fast spin echo sequence [driven-equilibrium imaging (DRIVE) or volumetric isotrophic T2-weighted acquisition (T2 VISTA)] and steady-state coherent fast GRE sequence (balanced turbo field echo; bTFE) imaging were performed in all patients. The patency of the aqueduct or third ventriculostomy site was scored. Some pitfalls of each sequence were also analyzed in individual cases. 93% of all cases showed consistent scores in PC-cine, DRIVE/T2 VISTA, and bTFE imaging. DRIVE/T2 VISTA imaging provided functional information of cerebrospinal fluid flow with flow-related artifacts, while bTFE imaging allowed direct visualization of the aqueduct or ventriculostomy site. However, evaluation of anatomical structures was difficult in three cases with strong flow-related artifacts on DRIVE/T2 VISTA and in 2 cases with susceptibility artifacts on bTFE. Both DRIVE/T2 VISTA and bTFE imaging have complementary roles in evaluating the patency of the aqueduct and 3rd ventriculostomy site.

  4. Spin asymmetries in inclusive cross sections

    International Nuclear Information System (INIS)

    Shima, T.

    1981-01-01

    Using the now closed Argonne ZGS polarized-proton beam, and the Michigan polarized-proton target, we have studied the one-spin and two-spin asymmetries of pion and proton production in the inclusive reactions p up arrow + p up arrow → p + Anything, and p up arrow + p up arrow → pi/sup +/ + Anything at P/sub lab/ = 6, 11.75, and 12.75 GeV/c. We observed experimental one-spin and two-spin asymmetries by scattering the polarized-proton beam from our polarized-proton target in each of the four possible initial spin states. These inclusive one-spin and two-spin asymmetries were calculated using the measured experimental spin asymmetries and three types of background measurements taken at P/sub lab/ = 6 and 11.75 GeV/c. We varied the transverse momentum P/sub perpendicular/) of the outgoing pion or proton from 0.71 to 1.55 GeV/c, and Feynman x variable from -0.08 to 0.67

  5. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  6. Experiences of ex-ex-gay individuals in sexual reorientation therapy: reasons for seeking treatment, perceived helpfulness and harmfulness of treatment, and post-treatment identification.

    Science.gov (United States)

    Flentje, Annesa; Heck, Nicholas C; Cochran, Bryan N

    2014-01-01

    Therapy meant to change someone's sexual orientation, or reorientation therapy, is still in practice despite statements from the major mental health organizations of its potential for harm. This qualitative study used an inductive content analysis strategy (Patton, 2002) to examine the experiences of thirty-eight individuals (31 males and seven females) who have been through a total of 113 episodes of reorientation therapy and currently identify as gay or lesbian. Religious beliefs were frequently cited as the reason for seeking reorientation therapy. Frequently endorsed themes of helpful components of reorientation therapy included connecting with others and feeling accepted. Harmful aspects of reorientation therapy included experiences of shame and negative impacts on mental health. Common reasons for identifying as LGB after the therapy included self-acceptance and coming to believe that sexual orientation change was not possible. The findings of this study were consistent with recommendations by the American Psychological Association Task Force on Appropriate Therapeutic Responses to Sexual Orientation (2009), which concluded that helpful aspects of reorientation therapy could be achieved through affirmative treatment methods while avoiding potential harms that may be associated with reorientation therapy. Limitations of the findings, including a small, self-selected sample, are discussed.

  7. Coherent collisional spin dynamics in optical lattices.

    Science.gov (United States)

    Widera, Artur; Gerbier, Fabrice; Fölling, Simon; Gericke, Tatjana; Mandel, Olaf; Bloch, Immanuel

    2005-11-04

    We report on the observation of coherent, purely collisionally driven spin dynamics of neutral atoms in an optical lattice. For high lattice depths, atom pairs confined to the same lattice site show weakly damped Rabi-type oscillations between two-particle Zeeman states of equal magnetization, induced by spin-changing collisions. Moreover, measurement of the oscillation frequency allows for precise determination of the spin-changing collisional coupling strengths, which are directly related to fundamental scattering lengths describing interatomic collisions at ultracold temperatures.

  8. Fast gaze reorientations by combined movements of the eye, head, trunk and lower extremities.

    Science.gov (United States)

    Anastasopoulos, Dimitri; Naushahi, J; Sklavos, Sokratis; Bronstein, Adolfo M

    2015-05-01

    Large reorientations of the line of sight, involving combined rotations of the eyes, head, trunk and lower extremities, are executed either as fast single-step or as slow multiple-step gaze transfers. In order to obtain more insight into the mechanisms of gaze and multisegmental movement control, we have investigated time-optimal gaze shifts (i.e. with the instruction to move as fast as possible) during voluntary whole-body rotations to remembered targets up to 180° eccentricity performed by standing healthy humans in darkness. Fast, accurate, single-step movement patterns occurred in approximately 70 % of trials, i.e. considerably more frequently than in previous studies with the instruction to turn at freely chosen speed (30 %). Head-in-space velocity in these cases was significantly higher than during multiple-step transfers and displayed a conspicuously regular bell-shaped profile, increasing smoothly to a peak and then decreasing slowly until realignment with the target. Head-in-space acceleration was on average not different during reorientations to the different target eccentricities. In contrast, head-in-space velocity increased with target eccentricity due to the longer duration of the acceleration phase implemented during trials to more distant targets. Eye saccade amplitude approached the eye-in-orbit mechanical limit and was unrelated to eye/head velocity, duration or target eccentricity. Overall, the combined movement was stereotyped such that the first two principal components accounted for data variance almost up to gaze shift end, suggesting that the three mechanical degrees of freedom under consideration (eye-in-orbit, head-on-trunk and trunk-in-space) are on average reduced to two kinematic degrees of freedom (i.e. eye, head-in-space). Synchronous EMG activity in the anterior tibial and gastrocnemius muscles preceded the onset of eye rotation. Since the magnitude and timing of peak head-in-space velocity were scaled with target eccentricity and

  9. Muon spin relaxation in random spin systems

    International Nuclear Information System (INIS)

    Toshimitsu Yamazaki

    1981-01-01

    The longitudinal relaxation function Gsub(z)(t) of the positive muon can reflect dynamical characters of local field in a unique way even when the correlation time is longer than the Larmor period of local field. This method has been applied to studies of spin dynamics in spin glass systems, revealing sharp but continuous temperature dependence of the correlation time. Its principle and applications are reviewed. (author)

  10. Cosmological model with macroscopic spin fluid

    OpenAIRE

    Szydlowski, Marek; Krawiec, Adam

    2003-01-01

    We consider a Friedmann-Robertson-Walker cosmological model with some exotic perfect fluid with spin known as the Weyssenhoff fluid. The possibility that the dark energy may be described in part by the Weyssenhoff fluid is discussed. The observational constraint coming from supernovae type Ia observations is established. This result indicates that, whereas the cosmological constant is still needed to explain current observations, the model with spin fluid is admissible. For high redshifts $z ...

  11. The susceptibilities in the spin-S Ising model

    International Nuclear Information System (INIS)

    Ainane, A.; Saber, M.

    1995-08-01

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

  12. Evidence of water reorientation on model electrocatalytic surfaces from nanosecond-laser-pulsed experiments.

    Science.gov (United States)

    García-Aráez, Nuria; Climent, Víctor; Feliu, Juan M

    2008-03-26

    The behavior of water at the interface formed between a quasi-perfect Pt(111) single-crystal electrode and an aqueous electrolyte solution is studied by means of the laser-induced temperature jump method. This method is based on the use of nanosecond laser pulses to suddenly increase the temperature at the interface. The measurement of the response of the interface toward the laser heating under coulostatic conditions provides evidence on the net orientation of water at the interface. Especially interesting is the study of the effect on the interfacial water caused by the selective deposition of foreign metal adatoms, because these bimetallic systems usually exhibit appealing electrocatalytic properties. The T-jump methodology shows that the surface composition strongly affects the interaction of water with the surface. The most representative parameter to characterize this interaction is the potential where water reorientation occurs; this potential shifts in different directions, depending on the relative values of the electronegativity of the adatom and the substrate. These results are discussed in the light of available information about the effect of adatom deposition on the work function and the surface potential of the modified surface. Finally, some implications on the enhancement of the electrocatalytic activity are briefly discussed.

  13. Embodiment and self in reorientation to everyday life following severe traumatic brain injury.

    Science.gov (United States)

    Sivertsen, Marianne; Normann, Britt

    2015-03-01

    People with severe traumatic brain injury (sTBI) are often young and need long-term follow-up as many suffer complex motor, sensory, perceptual and cognitive impairments. This paper aims to introduce phenomenological notions of embodiment and self as a framework to help understand how people with sTBI experience reorientation to everyday life, and to inform clinical practice in neurological physiotherapy. The impairments caused by the sTBI may lead to a sense of alienation of one's own body and changes in operative intentionality and in turn disrupt the reorganization of self, identity, everyday life and integration/co-construction of meaning with others. Applying a first-person conception of the body may extend insights into the importance of an adapted and individualized approach to strengthen the sensory, perceptual and motor body functions, which underpin the pre-reflective and reflective aspects of the self. It seems important to integrate these aspects, while also paying attention to optimizing co-construction of meaning for the person with sTBI in the treatment context. This requires understanding the patient as an experiencing and expressive body, a lived body (body-as-subject) and not just the body-as-object as is favored in more traditional frameworks of physiotherapy.

  14. Higher spin gauge theories

    CERN Document Server

    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...

  15. Spin caloritronics in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Angsula; Frota, H. O. [Department of Physics, Federal University of Amazonas, Av. Rodrigo Octavio 3000-Japiim, 69077-000 Manaus, AM (Brazil)

    2015-06-14

    Spin caloritronics, the combination of spintronics with thermoelectrics, exploiting both the intrinsic spin of the electron and its associated magnetic moment in addition to its fundamental electronic charge and temperature, is an emerging technology mainly in the development of low-power-consumption technology. In this work, we study the thermoelectric properties of a Rashba dot attached to two single layer/bilayer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current, which depends on the temperature and chemical potential. We demonstrate that the Rashba dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature, and also the Rashba term have been observed.

  16. Spin caloritronics in graphene

    Science.gov (United States)

    Frota, H. O.; Ghosh, Angsula

    2014-08-01

    Spin caloritronics, the combination of spintronics with thermoelectrics, based on spin and heat transport has attracted a great attention mainly in the development of low-power-consumption technology. In this work we study the thermoelectric properties of a quantum dot attached to two single layer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current which depends on the temperature and chemical potential. We demonstrate that the quantum dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature and also the Coulomb repulsion due to the double occupancy of an energy level have been observed.

  17. Spin and Maximal Acceleration

    Directory of Open Access Journals (Sweden)

    Giorgio Papini

    2017-12-01

    Full Text Available We study the spin current tensor of a Dirac particle at accelerations close to the upper limit introduced by Caianiello. Continual interchange between particle spin and angular momentum is possible only when the acceleration is time-dependent. This represents a stringent limit on the effect that maximal acceleration may have on spin physics in astrophysical applications. We also investigate some dynamical consequences of maximal acceleration.

  18. Spin Hall effect devices

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Wunderlich, Joerg; Olejník, Kamil

    2012-01-01

    Roč. 11, č. 5 (2012), s. 382-390 ISSN 1476-1122 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 35.749, year: 2012

  19. Spin coating apparatus

    Science.gov (United States)

    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.

  20. Pumped double quantum dot with spin-orbit coupling

    Directory of Open Access Journals (Sweden)

    Sherman Eugene

    2011-01-01

    Full Text Available Abstract We study driven by an external electric field quantum orbital and spin dynamics of electron in a one-dimensional double quantum dot with spin-orbit coupling. Two types of external perturbation are considered: a periodic field at the Zeeman frequency and a single half-period pulse. Spin-orbit coupling leads to a nontrivial evolution in the spin and orbital channels and to a strongly spin- dependent probability density distribution. Both the interdot tunneling and the driven motion contribute into the spin evolution. These results can be important for the design of the spin manipulation schemes in semiconductor nanostructures. PACS numbers: 73.63.Kv,72.25.Dc,72.25.Pn

  1. Ghost-spin chains, entanglement, and b c -ghost CFTs

    Science.gov (United States)

    Jatkar, Dileep P.; Narayan, K.

    2017-11-01

    We study one-dimensional chains of ghost-spins with nearest neighbor interactions amongst them, developing further the study of ghost-spins in previous work, defined as 2-state spin variables with indefinite norm. First we study finite ghost-spin chains with Ising-like nearest neighbor interactions: this helps organize and clarify the study of entanglement earlier, and we develop this further. Then we study a family of infinite ghost-spin chains with a different Hamiltonian containing nearest neighbor hopping-type interactions. By defining fermionic ghost-spin variables through a Jordan-Wigner transformation, we argue that these ghost-spin chains lead in the continuum limit to the b c -ghost conformal field theories.

  2. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  3. Quantum spin Hall phases

    International Nuclear Information System (INIS)

    Murakami, Shuichi

    2009-01-01

    We review our recent theoretical works on the quantum spin Hall effect. First we compare edge states in various 2D systems, and see whether they are robust or fragile against perturbations. Through the comparisons we see the robust nature of edge states in 2D quantum spin Hall phases. We see how it is protected by the Z 2 topological number, and reveal the nature of the Z 2 topological number by studying the phase transition between the quantum spin Hall and insulator phases. We also review our theoretical proposal of the ultrathin bismuth film as a candidate to the 2D quantum spin Hall system. (author)

  4. Local Noncollinear Spin Analysis.

    Science.gov (United States)

    Abate, Bayileyegn A; Joshi, Rajendra P; Peralta, Juan E

    2017-12-12

    In this work, we generalize the local spin analysis of Clark and Davidson [J. Chem. Phys. 2001 115 (16), 7382] for the partitioning of the expectation value of the molecular spin square operator, ⟨Ŝ 2 ⟩, into atomic contributions, ⟨Ŝ A ·Ŝ B ⟩, to the noncollinear spin case in the framework of density functional theory (DFT). We derive the working equations, and we show applications to the analysis of the noncollinear spin solutions of typical spin-frustrated systems and to the calculation of magnetic exchange couplings. In the former case, we employ the triangular H 3 He 3 test molecule and a Mn 3 complex to show that the local spin analysis provides additional information that complements the standard one-particle spin population analysis. For the calculation of magnetic exchange couplings, J AB , we employ the local spin partitioning to extract ⟨Ŝ A ·Ŝ B ⟩ as a function of the interatomic spin orientation given by the angle θ. This, combined with the dependence of the electronic energy with θ, provides a methodology to extract J AB from DFT calculations that, in contrast to conventional energy differences based methods, does not require the use of ad hoc S A and S B values.

  5. Spin glasses (II)

    International Nuclear Information System (INIS)

    Fischer, K.H.

    1985-01-01

    Experimental results of spin glass studies are reviewed and related to existing theories. Investigations of spin glasses are concentrated on atomic structure, metallurgical treatment, and high-temperature susceptibility of alloys, on magnetic properties at low temperature and near the freezing temperature, on anisotropy behaviour measured by ESR, NMR and torque, on specific heat, Moessbauer effect, neutron scattering and muon-spin depolarization experiments, ultrasound and transport properties. Some new theories of spin glasses are discussed which have been developed since Part I appeared

  6. Stationary and moving solitons in spin-orbit-coupled spin-1 Bose-Einstein condensates

    Science.gov (United States)

    Li, Yu-E.; Xue, Ju-Kui

    2018-04-01

    We investigate the matter-wave solitons in a spin-orbit-coupled spin-1 Bose-Einstein condensate using a multiscale perturbation method. Beginning with the one-dimensional spin-orbit-coupled threecomponent Gross-Pitaevskii equations, we derive a single nonlinear Schrödinger equation, which allows determination of the analytical soliton solutions of the system. Stationary and moving solitons in the system are derived. In particular, a parameter space for different existing soliton types is provided. It is shown that there exist only dark or bright solitons when the spin-orbit coupling is weak, with the solitons depending on the atomic interactions. However, when the spin-orbit coupling is strong, both dark and bright solitons exist, being determined by the Raman coupling. Our analytical solutions are confirmed by direct numerical simulations.

  7. Noise in tunneling spin current across coupled quantum spin chains

    OpenAIRE

    Aftergood, Joshua; Takei, So

    2017-01-01

    We theoretically study the spin current and its dc noise generated between two spin-1/2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a conc...

  8. High resolution incoherent quasielastic neutron scattering study of molecular reorientations of trimethylacetic acid (CH3) 3CCOOD in its low-temperature phase

    OpenAIRE

    Bée , M.; Poinsignon , C.; Longueville , W.; Amoureux , J.P.

    1983-01-01

    Using the incoherent quasielastic neutron scattering technique, we have studied the molecular reorientations of partially deuterated trimethylacetic acid (CH3)3CCOOD in its low temperature phase. The measurements were carried out with a sample temperature in the range from 80 K to 254 K, using an incoming neutron wavelength λ = 6.28 Å. The observed quasielastic spectra are consistent with a model allowing a combination of 120°-reorientations of the methyl and t-butyl groups.

  9. Effect of spin rotation coupling on spin transport

    International Nuclear Information System (INIS)

    Chowdhury, Debashree; Basu, B.

    2013-01-01

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

  10. Tunnel magnetoresistance in double spin filter junctions

    International Nuclear Information System (INIS)

    Saffarzadeh, Alireza

    2003-01-01

    We consider a new type of magnetic tunnel junction, which consists of two ferromagnetic tunnel barriers acting as spin filters (SFs), separated by a nonmagnetic metal (NM) layer. Using the transfer matrix method and the free-electron approximation, the dependence of the tunnel magnetoresistance (TMR) on the thickness of the central NM layer, bias voltage and temperature in the double SF junction are studied theoretically. It is shown that the TMR and electron-spin polarization in this structure can reach very large values under suitable conditions. The highest value of the TMR can reach 99%. By an appropriate choice of the thickness of the central NM layer, the degree of spin polarization in this structure will be higher than that of the single SF junctions. These results may be useful in designing future spin-polarized tunnelling devices

  11. Reorientation Timescales and Pattern Dynamics for Titan's Dunes: Does the Tail Wag the Dog or the Dragon?

    Science.gov (United States)

    Hayes, A. G.; Ewing, R. C.; Cassini Radar Science Team, T.

    2011-12-01

    Fields of bedform patterns persist across many orders of magnitude, from cm-scale sub-aqueous current ripples to km-scale aeolian dunes, and form with surprisingly little difference in expression despite a range of formative environments. Because of the remarkable similarity between and among patterns, extracting information about climate and environment from these patterns is a challenge. For example, crest orientation is not diagnostic of a particular flow regime; similar patterns form under many different flow configurations. On Titan, these challenges have played out with many attempts to reconcile dune-field patterns with modeled and expected wind regimes. We propose that thinking about the change in dune orientation, rather than the orientation itself, can provide new insights on the long-term stability of the dune-field patterns and the formative wind regime. In this work, we apply the re-orientation model presented by Werner and Kocurek [Geology, 1997] to the equatorial dune fields of Titan. We measure variations in pattern parameters (crest spacing, crest length and defect density, which is the number of defect pairs per total crest length) both within and between Titan's dune fields to describe pattern maturity and identify areas where changes in dune orientation are likely to occur (or may already be occurring). Measured defect densities are similar to Earth's largest linear dune fields, such as the Namib Sand Sea and the Simpson Desert. We use measured defect densities in the Werner and Kocurek model to estimate crestline reorientation rates. We find reorientation timescales varying from ten to a hundred thousand times the average migration timescale (time to migrate a bedform one meter, ~1 Titan year according to Tokano (Aeolian Research, 2010)). Well organized patterns have the longest reorientation time scales (~10^5 migration timescales), while the topographically or spatially isolated patches of dunes show the shortest reorientation times (~10

  12. Spin labels. Applications in biology

    International Nuclear Information System (INIS)

    Frangopol, T.P.; Frangopol, M.; Ionescu, S.M.; Pop, I.V.; Benga, G.

    1980-11-01

    The main applications of spin labels in the study of biomembranes, enzymes, nucleic acids, in pharmacology, spin immunoassay are reviewed along with the fundamentals of the spin label method. 137 references. (author)

  13. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  14. Re-orienting crop improvement for the changing climatic conditions of the 21st century

    Directory of Open Access Journals (Sweden)

    Mba Chikelu

    2012-06-01

    Full Text Available Abstract A 70% increase in food production is required over the next four decades to feed an ever-increasing population. The inherent difficulties in achieving this unprecedented increase are exacerbated by the yield-depressing consequences of climate change and variations and by the pressures on food supply by other competing demographic and socioeconomic demands. With the dwindling or stagnant agricultural land and water resources, the sought-after increases will therefore be attained mainly through the enhancement of crop productivity under eco-efficient crop production systems. ‘Smart’ crop varieties that yield more with fewer inputs will be pivotal to success. Plant breeding must be re-oriented in order to generate these ‘smart’ crop varieties. This paper highlights some of the scientific and technological tools that ought to be the staple of all breeding programs. We also make the case that plant breeding must be enabled by adequate policies, including those that spur innovation and investments. To arrest and reverse the worrisome trend of declining capacities for crop improvement, a new generation of plant breeders must also be trained. Equally important, winning partnerships, including public-private sector synergies, are needed for 21st century plant breeding to bear fruits. We also urge the adoption of the continuum approach to the management of plant genetic resources for food and agriculture as means to improved cohesion of the components of its value chain. Compellingly also, the National Agricultural Research and Extension System of developing countries require comprehensive overhauling and strengthening as crop improvement and other interventions require a sustained platform to be effective. The development of a suite of actionable policy interventions to be packaged for assisting countries in developing result-oriented breeding programs is also called for.

  15. Attentional reorienting triggers spatial asymmetries in a search task with cross-modal spatial cueing.

    Directory of Open Access Journals (Sweden)

    Rebecca E Paladini

    visual attention has to be reoriented towards the left hemifield.

  16. Reversible spin texture in ferroelectric Hf O2

    Science.gov (United States)

    Tao, L. L.; Paudel, Tula R.; Kovalev, Alexey A.; Tsymbal, Evgeny Y.

    2017-06-01

    Spin-orbit coupling effects occurring in noncentrosymmetric materials are known to be responsible for nontrivial spin configurations and a number of emergent physical phenomena. Ferroelectric materials may be especially interesting in this regard due to reversible spontaneous polarization making possible a nonvolatile electrical control of the spin degrees of freedom. Here, we explore a technologically relevant oxide material, Hf O2 , which has been shown to exhibit robust ferroelectricity in a noncentrosymmetric orthorhombic phase. Using theoretical modelling based on density-functional theory, we investigate the spin-dependent electronic structure of the ferroelectric Hf O2 and demonstrate the appearance of chiral spin textures driven by spin-orbit coupling. We analyze these spin configurations in terms of the Rashba and Dresselhaus effects within the k .p Hamiltonian model and find that the Rashba-type spin texture dominates around the valence-band maximum, while the Dresselhaus-type spin texture prevails around the conduction band minimum. The latter is characterized by a very large Dresselhaus constant λD= 0.578 eV Å, which allows using this material as a tunnel barrier to produce tunneling anomalous and spin Hall effects that are reversible by ferroelectric polarization.

  17. Spin, mass, and symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E. [Stanford Univ., CA (United States)

    1994-12-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.

  18. Physics lab in spin

    CERN Multimedia

    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).

  19. More spinoff from spin

    International Nuclear Information System (INIS)

    Masaike, Akira

    1993-01-01

    Despite playing a major role in today's Standard Model, spin - the intrinsic angular momentum carried by particles - is sometimes dismissed as an inessential complication. However several major spin questions with important implications for the Standard Model remain unanswered, and recent results and new technological developments made the 10th International Symposium on High Energy Spin Physics, held in Nagoya, Japan, in November, highly topical. The symposium covered a wide range of physics, reflecting the diversity of spin effects, however four main themes were - the spin content of the nucleon, tests of symmetries and physics beyond standard models, intermediate energy physics, and spin technologies. Opening the meeting, T. Kinoshita reviewed the status of measurements of the anomalous magnetic moment (g-2) of the electron and the muon. The forthcoming experiment at Brookhaven (September 1991, page 23) will probe beyond the energy ranges open to existing electronpositron colliders. For example muon substructure will be opened up to 5 TeV and Ws to 2 TeV. R.L. Jaffe classified quark-parton distributions in terms of their spin dependence, pointing out their leftright attributes, and emphasized the importance of measuring transverse spin distributions through lepton pair production

  20. Spin Hall noise

    NARCIS (Netherlands)

    Kamra, A.; Witek, F.P.; Meyer, S.; Huebl, H.; Geprägs, S.; Gross, R.; Bauer, G.E.W.; Goennenwein, S.T.B.

    2014-01-01

    We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle ? between the magnetization and the transport direction. The results are consistent

  1. 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.

  2. Spin, mass, and symmetry

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1994-01-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics

  3. Reorientation Timescales and Pattern Dynamics for Titan's Dunes: Does the Tail Wag the Dog or the Dragon?

    Science.gov (United States)

    Ewing, R. C.; Hayes, A. G.; McCormick, C.; Ballard, C.; Troy, S. A.

    2012-04-01

    Fields of bedform patterns persist across many orders of magnitude, from cm-scale sub-aqueous current ripples to km-scale aeolian dunes, and form with surprisingly little difference in expression despite a range of formative environments. Because of the remarkable similarity among bedform patterns, extracting information about climate and environment from these patterns is a challenge. For example, crestline orientation is not diagnostic of a particular flow regime; similar patterns form under many different flow configurations. On Titan, these challenges have played out with many attempts to reconcile dune crestline orientation with modeled and expected wind regimes. We propose that thinking about the time-scale of the change in dune orientation, rather than the orientation itself, can provide new insights on the long-term stability of the dune-field patterns and the formative wind regime. In this work, we apply the crestline re-orientation model developed by Werner and Kocurek [Geology, 1997] to the equatorial dune fields of Titan. We use Cassini Synthetic Aperture Radar images processed through a de-noising algorithm recently developed by Lucas et al. [LPSC, 2012] to measure variations in pattern parameters (crest spacing, crest length and defect density, which is the number of defect pairs per total crest length) both within and between Titan's dune fields to describe pattern maturity and identify areas where changes in dune orientation are likely to occur (or may already be occurring). Measured defect densities are similar to Earth's largest linear dune fields, such as the Namib Sand Sea and the Simpson Desert. We use measured defect densities in the Werner and Kocurek model to estimate crestline reorientation rates. We find reorientation timescales varying from ten to a hundred thousand times the average migration timescale (time to migrate a bedform one meter, ~1 Titan year according to Tokano (Aeolian Research, 2010)). Well-organized patterns have the

  4. Ising-type anisotropy and spin state transitions in GdBaCo2O5.5 from first-principles calculations

    International Nuclear Information System (INIS)

    Pardo, V.; Baldomir, D.; Castro, J.; Iglesias, M.; Arias, J.E.

    2007-01-01

    Ising-type behaviour of GdBaCo 2 O 5.5 is analyzed from first principles calculations of the electronic structure of the material. The variations in its magnetic anisotropy properties in the different possible magnetic configurations is analyzed. A possible metallic phase is studied and an analysis of the electronic structure of the Co 3+ ions in that phase is presented

  5. Spin Waves in Terbium

    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...

  6. ISOTROPIC HEATING OF GALAXY CLUSTER CORES VIA RAPIDLY REORIENTING ACTIVE GALACTIC NUCLEUS JETS

    International Nuclear Information System (INIS)

    Babul, Arif; Sharma, Prateek; Reynolds, Christopher S.

    2013-01-01

    Active galactic nucleus (AGN) jets carry more than sufficient energy to stave off catastrophic cooling of the intracluster medium (ICM) in the cores of cool-core clusters. However, in order to prevent catastrophic cooling, the ICM must be heated in a near-isotropic fashion and narrow bipolar jets with P jet = 10 44–45 erg s –1 , typical of radio AGNs at cluster centers, are inefficient in heating the gas in the transverse direction to the jets. We argue that due to existent conditions in cluster cores, the supermassive black holes (SMBHs) will, in addition to accreting gas via radiatively inefficient flows, experience short stochastic episodes of enhanced accretion via thin disks. In general, the orientation of these accretion disks will be misaligned with the spin axis of the black holes (BHs) and the ensuing torques will cause the BH's spin axis (and therefore the jet axis) to slew and rapidly change direction. This model not only explains recent observations showing successive generations of jet-lobes-bubbles in individual cool-core clusters that are offset from each other in the angular direction with respect to the cluster center, but also shows that AGN jets can heat the cluster core nearly isotropically on the gas cooling timescale. Our model does require that the SMBHs at the centers of cool-core clusters be spinning relatively slowly. Torques from individual misaligned disks are ineffective at tilting rapidly spinning BHs by more than a few degrees. Additionally, since SMBHs that host thin accretion disks will manifest as quasars, we predict that roughly 1-2 rich clusters within z < 0.5 should have quasars at their centers.

  7. Spin Hall and spin swapping torques in diffusive ferromagnets

    KAUST Repository

    Pauyac, C. O.

    2017-12-08

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

  8. Orbital and spin moments in the ferromagnetic superconductor URhGe by x-ray magnetic circular dichroism

    Science.gov (United States)

    Wilhelm, F.; Sanchez, J. P.; Brison, J.-P.; Aoki, D.; Shick, A. B.; Rogalev, A.

    2017-06-01

    The ferromagnetic superconductor URhGe has been investigated by high field magnetic circular dichroism (XMCD) at the U M4 ,5, Rh L2 ,3, and Ge K edges at 2.1 K and at applied fields up to 17 T. The XMCD performed at the M4 ,5 absorption edges allows us to determine the spectroscopic branching ratio and the 5 f electron contribution to the valence spin-orbit interaction. Combination with polarized neutron diffraction results allows us to derive the individual U orbital and spin moments and the magnetic-dipole contribution . There is no evidence for any change of the orbital-to-spin moment ratios across the spin reorientation transition at HR=12 T , when the field is applied along the initial hard b axis. We also confirm that the magnetism of URhGe is dominated by U , with the contribution of Rh representing only about 10 % of the macroscopic moment. The orbital and spin moments at the Rh site are found to be parallel to each other and parallel to the macroscopic magnetization, but an unexpectedly large orbital-to-spin moment ratio is observed. The XMCD at the Ge K edge reveals the presence of a small induced Ge 4 p orbital moment, parallel to the macroscopic magnetization. The results are discussed against predictions of the electronic band structure calculations by the density functional theory plus Coulomb U , including spin-orbit coupling (DFT +U +SOC ) .

  9. Spin diffusion and1H spin-lattice relaxation in Cs2(HSO4)(H2PO4) containing a small amount of ammonium ions.

    Science.gov (United States)

    Hayashi, Shigenobu; Jimura, Keiko

    2017-11-01

    Inorganic solid acid salts with hydrogen bond networks frequently show very long spin-lattice relaxation times even for 1 H because the hydrogen bonds suppress motions. In the present work, the 1 H spin-lattice relaxation in Cs 2 (HSO 4 )(H 2 PO 4 ) containing a small amount of ammonium ions were studied in detail by use of the effect of magic angle spinning (MAS) on the relaxation. The 1 H spin-lattice relaxation times of the acid protons decrease with increase in the content of ammonium ions. Reorientation of the NH 4 group fluctuates the dipole-dipole interaction and relaxes the ammonium protons as well as the acid protons. The 1 H relaxation times of the acid protons are a little bit longer than those of the ammonium protons at the MAS rate of 8 kHz. The spinning at 50 kHz makes the relaxation times of the acid protons longer and those of the ammonium protons shorter. Spin diffusion between the acid and the ammonium protons averages partially the 1 H relaxation of the acid and the ammonium protons at the MAS rate of 8 kHz. The spin diffusion is suppressed completely at the MAS rate of 50 kHz. Spin diffusion between the acid protons is not suppressed at the MAS rate of 50 kHz. The acid protons always show the same relaxation times. The intrinsic relaxation times not affected by spin diffusion are evaluated quantitatively for both the acid and the ammonium protons. Those values are independent of the ammonium content. Contribution of the spin diffusion between the acid and the ammonium protons to the relaxation is estimated quantitatively. Using those parameters, the effect of ammonium ions on the 1 H spin-lattice relaxation can be predicted. The 1 H spin-lattice relaxation is a sensitive tool to study the distribution of ammonium ions in solids. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet with √{3} × √{3} -Type Distortion — Behavior around the Boundaries of the Intermediate Phase

    Science.gov (United States)

    Shimada, Alisa; Nakano, Hiroki; Sakai, Tôru; Yoshimura, Kazuyoshi

    2018-03-01

    The S = 1/2 triangular-lattice Heisenberg antiferromagnet with distortion is investigated by the numerical-diagonalization method. The examined distortion type is √{3} × √{3} . We study the case when the distortion connects the undistorted triangular lattice and the dice lattice. For the intermediate phase reported previously in this system, we obtain results of the boundaries of the intermediate phase for a larger system than those in the previous report and examine the system size dependence of the boundaries in detail. We also report the specific heat of this system, which shows a marked peak structure related to the appearance of the intermediate state.

  11. Magnetic, ferroelectric, and spin phonon coupling studies of Sr{sub 3}Co{sub 2}Fe{sub 24}O{sub 41} multiferroic Z-type hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Raju, N.; Shravan Kumar Reddy, S.; Ramesh, J.; Gopal Reddy, Ch.; Yadagiri Reddy, P., E-mail: yadagirireddy@yahoo.com; Rama Reddy, K. [Department of Physics, Osmania University, Hyderabad-500007 (India); Sathe, V. G.; Raghavendra Reddy, V. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001 (India)

    2016-08-07

    The magnetic, Raman, ferroelectric, and in-field {sup 57}Fe Mössbauer studies of polycrystalline multiferroic Sr{sub 3}Co{sub 2}Fe{sub 24}O{sub 41} are reported in this paper. From the magnetization studies, it is observed that the sample is soft magnetic in nature with low temperature magnetic spin transitions like longitudinal to transverse conical structure around 130 K and change in magnetic crystalline anisotropy from conical to planar structure at 250 K. Ferroelectric studies of the sample exhibit the spontaneous polarization at low temperature. Strong spin phonon and spin lattice coupling is observed through low temperature Raman spectroscopy. From the in-field {sup 57}Fe Mössbauer spectroscopy, spin up and spin down site occupations of Fe ions are calculated in the unit cell.

  12. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  13. Nuclear spins in nanostructures

    International Nuclear Information System (INIS)

    Coish, W.A.; Baugh, J.

    2009-01-01

    We review recent theoretical and experimental advances toward understanding the effects of nuclear spins in confined nanostructures. These systems, which include quantum dots, defect centers, and molecular magnets, are particularly interesting for their importance in quantum information processing devices, which aim to coherently manipulate single electron spins with high precision. On one hand, interactions between confined electron spins and a nuclear-spin environment provide a decoherence source for the electron, and on the other, a strong effective magnetic field that can be used to execute local coherent rotations. A great deal of effort has been directed toward understanding the details of the relevant decoherence processes and to find new methods to manipulate the coupled electron-nuclear system. A sequence of spectacular new results have provided understanding of spin-bath decoherence, nuclear spin diffusion, and preparation of the nuclear state through dynamic polarization and more general manipulation of the nuclear-spin density matrix through ''state narrowing.'' These results demonstrate the richness of this physical system and promise many new mysteries for the future. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  14. Spin drift and spin diffusion currents in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-09-15

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

  15. 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.

  16. Spin drift and spin diffusion currents in semiconductors

    International Nuclear Information System (INIS)

    Idrish Miah, M

    2008-01-01

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

  17. Higher spins and holography

    Science.gov (United States)

    Kraus, Per; Ross, Simon F.

    2013-05-01

    The principles of quantum mechanics and relativity impose rigid constraints on theories of massless particles with nonzero spin. Indeed, Yang-Mills theory and General Relativity are the unique solution in the case of spin-1 and spin-2. In asymptotically flat spacetime, there are fundamental obstacles to formulating fully consistent interacting theories of particles of spin greater than 2. However, indications are that such theories are just barely possible in asymptotically anti-de Sitter or de Sitter spacetimes, where the non-existence of an S-matrix provides an escape from the theorems restricting theories in Minkowski spacetime. These higher spin gravity theories are therefore of great intrinsic interest, since they, along with supergravity, provide the only known field theories generalizing the local invariance principles of Yang-Mills theory and General Relativity. While work on higher spin gravity goes back several decades, the subject has gained broader appeal in recent years due to its appearance in the AdS/CFT correspondence. In three and four spacetime dimensions, there exist duality proposals linking higher spin gravity theories to specific conformal field theories living in two and three dimensions respectively. The enlarged symmetry algebra of the conformal field theories renders them exactly soluble, which makes them excellent laboratories for understanding in detail the holographic mechanism behind AdS/CFT duality. Steady progress is also being made on better understanding the space of possible higher spin gravity theories and their physical content. This work includes classifying the possible field multiplets and their interactions, constructing exact solutions of the nonlinear field equations, and relating higher spin theories to string theory. A full understanding of these theories will involve coming to grips with the novel symmetry principles that enlarge those of General Relativity and Yang-Mills theory, and one can hope that this will provide

  18. Spin transfer torque with spin diffusion in magnetic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2012-08-09

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

  19. Electron spin and nuclear spin manipulation in semiconductor nanosystems

    International Nuclear Information System (INIS)

    Hirayama, Yoshiro; Yusa, Go; Sasaki, Satoshi

    2006-01-01

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

  20. Spins in chemistry

    CERN Document Server

    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

  1. Frustrated spin systems

    CERN Document Server

    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

  2. Spin Hall effect transistor

    Czech Academy of Sciences Publication Activity Database

    Wunderlich, Joerg; Park, B.G.; Irvine, A.C.; Zarbo, Liviu; Rozkotová, E.; Němec, P.; Novák, Vít; Sinova, Jairo; Jungwirth, Tomáš

    2010-01-01

    Roč. 330, č. 6012 (2010), s. 1801-1804 ISSN 0036-8075 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 31.364, year: 2010

  3. Spin tracking in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luccio, A.U. [Brookhaven National Lab., Upton, NY (United States); Katayama, T. [Univ. of Tokyo (Japan); Wu, H. [Riken Inst., Tokyo (Japan)

    1997-07-01

    In the acceleration of polarized protons in RHIC many spin depolarizing resonances are encountered. Helical Siberian snakes will be used to overcome depolarizing effects. The behavior of polarization can be studied by numerical tracking in a model accelerator. That allows one to check the strength of the resonances, to study the effect of snakes, to find safe lattice tune regions, and finally to study the operation of special devices like spin flippers. In this paper the authors describe numerical spin tracking. Results show that, for the design corrected distorted orbit and the design beam emittance, the polarization of the beam will be preserved in the whole range of proton energies in RHIC.

  4. SPINning parallel systems software

    International Nuclear Information System (INIS)

    Matlin, O.S.; Lusk, E.; McCune, W.

    2002-01-01

    We describe our experiences in using Spin to verify parts of the Multi Purpose Daemon (MPD) parallel process management system. MPD is a distributed collection of processes connected by Unix network sockets. MPD is dynamic processes and connections among them are created and destroyed as MPD is initialized, runs user processes, recovers from faults, and terminates. This dynamic nature is easily expressible in the Spin/Promela framework but poses performance and scalability challenges. We present here the results of expressing some of the parallel algorithms of MPD and executing both simulation and verification runs with Spin

  5. FY 2016 Status Report: CIRFT Testing on Spent Nuclear Fuels and Hydride Reorientation Study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Yan, Yong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Bevard, Bruce B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Scaglione, John M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2016-08-04

    This report provides a detailed description of the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) testing conducted on spent nuclear fuel (SNF) rods in FY 2016, including hydride reorientation test results. Contact-based measurement, or three-LVDT-based curvature measurement, of SNF rods has proven to be quite reliable in CIRFT testing. However, how the linear variable differential transformer (LVDT) head contacts the SNF rod may have a significant effect on the curvature measurement, depending on the magnitude and direction of rod curvature. To correct such contact/curvature issues, sensor spacing, defined as the amount of separation between the three LVDT probes, is a critical measurement that can be used to calculate rod curvature once the deflections are obtained. Recently developed CIRFT data analyses procedures were integrated into FY 2016 CIRFT testing results for the curvature measurements. The variations in fatigue life are provided in terms of moment, equivalent stress, curvature, and equivalent strain for the tested SNFs. The equivalent stress plot collapsed the data points from all of the SNFs into a single zone. A detailed examination revealed that, at same stress level, fatigue lives display a descending order as follows: H. B. Robinson Nuclear Power Station (HBR), Limerick Nuclear Power Station (LMK), mixed uranium-plutonium oxide (MOX). If looking at the strain, then LMK fuel has a slightly longer fatigue life than HBR fuel, but the difference is subtle. The knee point of endurance limit in the curve of moment and curvature or equivalent quantities is more clearly defined for LMK and HBR fuels. The treatment affects the fatigue life of specimens. Both a drop of 12 in. and radial hydride treatment (RHT) have a negative impact on fatigue life. The effect of thermal annealing on MOX fuel rods was relatively small at higher amplitude but became significant at low amplitude of moment. Thermal annealing tended to extend the fatigue life of

  6. FY 2016 Status Report: Documentation of All CIRFT Data including Hydride Reorientation Tests (Draft M2)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Jiang, Hao [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Yan, Yong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Bevard, Bruce B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Scaglione, John M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2016-09-04

    The first portion of this report provides a detailed description of fiscal year (FY) 2015 test result corrections and analysis updates based on FY 2016 updates to the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) program methodology, which is used to evaluate the vibration integrity of spent nuclear fuel (SNF) under normal conditions of transport (NCT). The CIRFT consists of a U-frame test setup and a real-time curvature measurement method. The three-component U-frame setup of the CIRFT has two rigid arms and linkages connecting to a universal testing machine. The curvature SNF rod bending is obtained through a three-point deflection measurement method. Three linear variable differential transformers (LVDTs) are clamped to the side connecting plates of the U-frame and used to capture deformation of the rod. The second portion of this report provides the latest CIRFT data, including data for the hydride reorientation test. The variations in fatigue life are provided in terms of moment, equivalent stress, curvature, and equivalent strain for the tested SNFs. The equivalent stress plot collapsed the data points from all of the SNF samples into a single zone. A detailed examination revealed that, at the same stress level, fatigue lives display a descending order as follows: H. B. Robinson Nuclear Power Station (HBR), LMK, and mixed uranium-plutonium oxide (MOX). Just looking at the strain, LMK fuel has a slightly longer fatigue life than HBR fuel, but the difference is subtle. The third portion of this report provides finite element analysis (FEA) dynamic deformation simulation of SNF assemblies . In a horizontal layout under NCT, the fuel assembly’s skeleton, which is formed by guide tubes and spacer grids, is the primary load bearing apparatus carrying and transferring vibration loads within an SNF assembly. These vibration loads include interaction forces between the SNF assembly and the canister basket walls. Therefore, the integrity of the guide

  7. Statistical methods of spin assignment in compound nuclear reactions

    International Nuclear Information System (INIS)

    Mach, H.; Johns, M.W.

    1984-01-01

    Spin assignment to nuclear levels can be obtained from standard in-beam gamma-ray spectroscopy techniques and in the case of compound nuclear reactions can be complemented by statistical methods. These are based on a correlation pattern between level spin and gamma-ray intensities feeding low-lying levels. Three types of intensity and level spin correlations are found suitable for spin assignment: shapes of the excitation functions, ratio of intensity at two beam energies or populated in two different reactions, and feeding distributions. Various empirical attempts are examined and the range of applicability of these methods as well as the limitations associated with them are given. 12 references

  8. Statistical methods of spin assignment in compound nuclear reactions

    International Nuclear Information System (INIS)

    Mach, H.; Johns, M.W.

    1985-01-01

    Spin assignment to nuclear levels can be obtained from standard in-beam gamma-ray spectroscopy techniques and in the case of compound nuclear reactions can be complemented by statistical methods. These are based on a correlation pattern between level spin and gamma-ray intensities feeding low-lying levels. Three types of intensity and level spin correlations are found suitable for spin assignment: shapes of the excitation functions, ratio of intensity at two beam energies or populated in two different reactions, and feeding distributions. Various empirical attempts are examined and the range of applicability of these methods as well as the limitations associated with them are given

  9. Quantum communication and state transfer in spin chains

    International Nuclear Information System (INIS)

    Van der Jeugt, Joris

    2011-01-01

    We investigate the time evolution of a single spin excitation state in certain linear spin chains, as a model for quantum communication. We consider first the simplest possible spin chain, where the spin chain data (the nearest neighbour interaction strengths and the magnetic field strengths) are constant throughout the chain. The time evolution of a single spin state is determined, and this time evolution is illustrated by means of an animation. Some years ago it was discovered that when the spin chain data are of a special form so-called perfect state transfer takes place. These special spin chain data can be linked to the Jacobi matrix entries of Krawtchouk polynomials or dual Hahn polynomials. We discuss here the case related to Krawtchouk polynomials, and illustrate the possibility of perfect state transfer by an animation showing the time evolution of the spin chain from an initial single spin state. Very recently, these ideas were extended to discrete orthogonal polynomials of q-hypergeometric type. Here, a remarkable result is a new analytic model where perfect state transfer is achieved: this is when the spin chain data are related to the Jacobi matrix of q-Krawtchouk polynomials. This case is discussed here, and again illustrated by means of an animation.

  10. Lithium ion diffusion measurements on a garnet-type solid conductor Li6.6La3Zr1.6Ta0.4O12 by using a pulsed-gradient spin-echo NMR method.

    Science.gov (United States)

    Hayamizu, Kikuko; Matsuda, Yasuaki; Matsui, Masaki; Imanishi, Nobuyuki

    2015-09-01

    The garnet-type solid conductor Li7-xLa3Zr2-xTaxO12 is known to have high ionic conductivity. We synthesized a series of compositions of this conductor and found that cubic Li6.6La3Zr1.6Ta0.4O12 (LLZO-Ta) has a high ionic conductivity of 3.7×10(-4)Scm(-1) at room temperature. The (7)Li NMR spectrum of LLZO-Ta was composed of narrow and broad components, and the linewidth of the narrow component varied from 0.69kHz (300K) to 0.32kHz (400K). We carried out lithium ion diffusion measurements using pulsed-field spin-echo (PGSE) NMR spectroscopy and found that echo signals were observed at T≥313K with reasonable sensitivity. The lithium diffusion behavior was measured by varying the observation time and pulsed-field gradient (PFG) strength between 313 and 384K. We found that lithium diffusion depended significantly on the observation time and strength of the PFG, which is quite different from lithium ion diffusion in liquids. It was shown that lithium ion migration in the solid conductor was distributed widely in both time and space. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    2 states. A coherent spin-s state. (CSS) θ φ can then be thought of as having no quantum correlations as the constituent. 2s elementary spins point in the same direction ˆn(θ φ) which is the mean spin direction. 2. State classification and squeezing. In order to discuss squeezing, we begin with the squeezing condition itself.

  12. Geometry of spin coherent states

    Science.gov (United States)

    Chryssomalakos, C.; Guzmán-González, E.; Serrano-Ensástiga, E.

    2018-04-01

    Spin states of maximal projection along some direction in space are called (spin) coherent, and are, in many respects, the ‘most classical’ available. For any spin s, the spin coherent states form a 2-sphere in the projective Hilbert space \

  13. Ballistic spin filtering across the ferromagnetic-semiconductor interface

    Directory of Open Access Journals (Sweden)

    Y.H. Li

    2012-03-01

    Full Text Available The ballistic spin-filter effect from a ferromagnetic metal into a semiconductor has theoretically been studied with an intention of detecting the spin polarizability of density of states in FM layer at a higher energy level. The physical model for the ballistic spin filtering across the interface between ferromagnetic metals and semiconductor superlattice is developed by exciting the spin polarized electrons into n-type AlAs/GaAs superlattice layer at a much higher energy level and then ballistically tunneling through the barrier into the ferromagnetic film. Since both the helicity-modulated and static photocurrent responses are experimentally measurable quantities, the physical quantity of interest, the relative asymmetry of spin-polarized tunneling conductance, could be extracted experimentally in a more straightforward way, as compared with previous models. The present physical model serves guidance for studying spin detection with advanced performance in the future.

  14. Towards a spin-ensemble quantum memory for superconducting qubits

    Science.gov (United States)

    Grezes, Cécile; Kubo, Yuimaru; Julsgaard, Brian; Umeda, Takahide; Isoya, Junichi; Sumiya, Hitoshi; Abe, Hiroshi; Onoda, Shinobu; Ohshima, Takeshi; Nakamura, Kazuo; Diniz, Igor; Auffeves, Alexia; Jacques, Vincent; Roch, Jean-François; Vion, Denis; Esteve, Daniel; Moelmer, Klaus; Bertet, Patrice

    2016-08-01

    This article reviews efforts to build a new type of quantum device, which combines an ensemble of electronic spins with long coherence times, and a small-scale superconducting quantum processor. The goal is to store over long times arbitrary qubit states in orthogonal collective modes of the spin-ensemble, and to retrieve them on-demand. We first present the protocol devised for such a multi-mode quantum memory. We then describe a series of experimental results using NV (as in nitrogen vacancy) center spins in diamond, which demonstrate its main building blocks: the transfer of arbitrary quantum states from a qubit into the spin ensemble, and the multi-mode retrieval of classical microwave pulses down to the single-photon level with a Hahn-echo like sequence. A reset of the spin memory is implemented in-between two successive sequences using optical repumping of the spins. xml:lang="fr"

  15. Reorientational optical nonlinearity of nematic liquid-crystal cells near the nematic-isotropic phase transition temperature.

    Science.gov (United States)

    Tsai, Ming-Shan; Jiang, I-Min; Huang, Chi-Yen; Shih, Chia-Chi

    2003-12-01

    We address the reorientational optical nonlinearity of homogeneously aligned neamtic liquid-crystal (NLC) cells. The propagation of light in NLC cells depend strongly on temperature. At a temperature approaching the clearing point, an undulating beam and multifocal points are observed in the NLC cell by use of a polarizing optical microscope. Using a conoscopic technique, we observed novel consecutive concentric and parabolic patterns projected onto a screen. Optical energy is considered to compete with thermal energy to affect NLC's orientation and to generate singularities in the steady state. A model of the configuration of the liquid crystal's orientation is proposed.

  16. Reorientational optical nonlinearity of nematic liquid-crystal cells near the nematic-isotropic phase transition temperature

    Science.gov (United States)

    Tsai, Ming-Shan; Jiang, I.-Min; Huang, Chi-Yen; Shih, Chia-Chi

    2003-12-01

    We address the reorientational optical nonlinearity of homogeneously aligned neamtic liquid-crystal (NLC) cells. The propagation of light in NLC cells depend strongly on temperature. At a temperature approaching the clearing point, an undulating beam and multifocal points are observed in the NLC cell by use of a polarizing optical microscope. Using a conoscopic technique, we observed novel consecutive concentric and parabolic patterns projected onto a screen. Optical energy is considered to compete with thermal energy to affect NLC's orientation and to generate singularities in the steady state. A model of the configuration of the liquid crystal's orientation is proposed.

  17. Spin Hall effect and spin swapping in diffusive superconductors

    Science.gov (United States)

    Espedal, Camilla; Lange, Peter; Sadjina, Severin; Mal'shukov, A. G.; Brataas, Arne

    2017-02-01

    We consider the spin-orbit-induced spin Hall effect and spin swapping in diffusive superconductors. By employing the nonequilibrium Keldysh Green's function technique in the quasiclassical approximation, we derive coupled transport equations for the spectral spin and particle distributions and for the energy density in the elastic scattering regime. We compute four contributions to the spin Hall conductivity, namely, skew scattering, side jump, anomalous velocity, and the Yafet contribution. The reduced density of states in the superconductor causes a renormalization of the spin Hall angle. We demonstrate that all four of these contributions to the spin Hall conductivity are renormalized in the same way in the superconducting state. In its simplest manifestation, spin swapping transforms a primary spin current into a secondary spin current with swapped current and polarization directions. We find that the spin-swapping coefficient is not explicitly but only implicitly affected by the superconducting gap through the renormalized diffusion coefficients. We discuss experimental consequences for measurements of the (inverse) spin Hall effect and spin swapping in four-terminal geometries. In our geometry, below the superconducting transition temperature, the spin-swapping signal is increased an order of magnitude while changes in the (inverse) spin Hall signal are moderate.

  18. 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.

  19. Spin-polarized scanning tunneling microscopy of magnetic nanostructures at the example of bcc-Co/Fe(110), Fe/Mo(110), and copper phthalocyanine/Fe(1110); Spinpolarisierte Rastertunnelmikroskopie magnetischer Nanostrukturen am Beispiel von bcc-Co/Fe(110), Fe/Mo(110) und Kupfer-Phthalocyanin/Fe(110)

    Energy Technology Data Exchange (ETDEWEB)

    Methfessel, Torsten

    2010-12-09

    This thesis provides an introduction into the technique of spin-polarized scanning tunnelling microscopy and spectroscopy as an experimental method for the investigation of magnetic nanostructures. Experimental results for the spin polarized electronic structure depending on the crystal structure of ultrathin Co layers, and depending on the direction of the magnetization for ultrathin Fe layers are presented. High-resolution measurements show the position-dependent spin polarization on a single copper-phthalocyanine molecule deposited on a ferromagnetic surface. Co was deposited by molecular beam epitaxy on the (110) surface of the bodycentered cubic metals Cr and Fe. In contrast to previous reports in the literature only two layers of Co can be stabilized in the body-centered cubic (bcc) structure. The bcc-Co films on the Fe(110) surface show no signs of epitaxial distortions. Thicker layers reconstruct into a closed-packed structure (hcp / fcc). The bcc structure increases the spin-polarization of Co to P=62 % in comparison to hcp-Co (P=45 %). The temperature-dependent spin-reorientation of ultrathin Fe/Mo(110) films was investigated by spin-polarized spectroscopy. A reorientation of the magnetic easy axis from the [110] direction along the surface normal to the in-plane [001] axis is observed at T (13.2{+-}0.5) K. This process can be identified as a discontinuous reorientation transition, revealing two simultaneous minima of the free energy in a certain temperature range. The electronic structure of mono- and double-layer Fe/Mo(110) shows a variation with the reorientation of the magnetic easy axis and with the direction of the magnetization. The investigation of the spin-polarized charge transport through a copper-phthalocyanine molecule on the Fe/Mo(110) surface provides an essential contribution to the understanding of spin-transport at the interface between metal and organic molecule. Due to the interaction with the surface of the metal the HOMO-LUMO energy

  20. Higher Spins & Strings

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The conjectured relation between higher spin theories on anti de-Sitter (AdS) spaces and weakly coupled conformal field theories is reviewed. I shall then outline the evidence in favour of a concrete duality of this kind, relating a specific higher spin theory on AdS3 to a family of 2d minimal model CFTs. Finally, I shall explain how this relation fits into the framework of the familiar stringy AdS/CFT correspondence.

  1. Quantum spin quadrumer

    Science.gov (United States)

    Khatua, Subhankar; Shankar, R.; Ganesh, R.

    2018-02-01

    A fundamental motif in frustrated magnetism is the fully mutually coupled cluster of N spins, with each spin coupled to every other spin. Clusters with N =2 and 3 have been extensively studied as building blocks of square and triangular lattice antiferromagnets. In both cases, large-S semiclassical descriptions have been fruitfully constructed, providing insights into the physics of macroscopic magnetic systems. Here, we develop a semiclassical theory for the N =4 cluster. This problem has rich mathematical structure with a ground-state space that has nontrivial topology. We show that ground states are appropriately parametrized by a unit vector order parameter and a rotation matrix. Remarkably, in the low-energy description, the physics of the cluster reduces to that of an emergent free spin-S spin and a rigid rotor. This successfully explains the spectrum of the quadrumer and its associated degeneracies. However, this mapping does not hold in the vicinity of collinear ground states due to a subtle effect that arises from the nonmanifold nature of the ground-state space. We demonstrate this by an analysis of soft fluctuations, showing that collinear states have a larger number of soft modes. Nevertheless, as these singularities only occur on a subset of measure zero, the mapping to a spin and a rotor provides a good description of the quadrumer. We interpret thermodynamic properties of the quadrumer that are accessible in molecular magnets, in terms of the rotor and spin degrees of freedom. Our study paves the way for field theoretic descriptions of systems such as pyrochlore magnets.

  2. Spider Spinning for Dummies

    Science.gov (United States)

    Bird, Richard S.

    Spider spinning is a snappy name for the problem of listing the ideals of a totally acyclic poset in such a way that each ideal is computed from its predecessor in constant time. Such an algorithm is said to be loopless. Our aim in these lectures is to show how to calculate a loopless algorithm for spider spinning. The calculation makes use of the fundamental laws of functional programming and the real purpose of the exercise is to show these laws in action.

  3. Quantum decoration transformation for spin models

    International Nuclear Information System (INIS)

    Braz, F.F.; Rodrigues, F.C.; Souza, S.M. de; Rojas, Onofre

    2016-01-01

    It is quite relevant the extension of decoration transformation for quantum spin models since most of the real materials could be well described by Heisenberg type models. Here we propose an exact quantum decoration transformation and also showing interesting properties such as the persistence of symmetry and the symmetry breaking during this transformation. Although the proposed transformation, in principle, cannot be used to map exactly a quantum spin lattice model into another quantum spin lattice model, since the operators are non-commutative. However, it is possible the mapping in the “classical” limit, establishing an equivalence between both quantum spin lattice models. To study the validity of this approach for quantum spin lattice model, we use the Zassenhaus formula, and we verify how the correction could influence the decoration transformation. But this correction could be useless to improve the quantum decoration transformation because it involves the second-nearest-neighbor and further nearest neighbor couplings, which leads into a cumbersome task to establish the equivalence between both lattice models. This correction also gives us valuable information about its contribution, for most of the Heisenberg type models, this correction could be irrelevant at least up to the third order term of Zassenhaus formula. This transformation is applied to a finite size Heisenberg chain, comparing with the exact numerical results, our result is consistent for weak xy-anisotropy coupling. We also apply to bond-alternating Ising–Heisenberg chain model, obtaining an accurate result in the limit of the quasi-Ising chain.

  4. Spin-engineered quantum dots

    OpenAIRE

    Fleurov, V.; Ivanov, V. A.; Peeters, F. M.; Vagner, I. D.

    2001-01-01

    Spatially nonhomogeneously spin polarized nuclei are proposed as a new mechanism to monitor electron states in a nanostructure, or as a means to createn and, if necessary, reshape such nanostructures in the course of the experiment. We found that a polarization of nulear spins may lift the spin polarization of the electron states in a nanostructure and, if sufficiently strong, leads to a polarization of the electron spins. Polarized nuclear spins may form an energy landscape capable of bindin...

  5. Theory of spin Hall effect

    OpenAIRE

    Chudnovsky, Eugene M.

    2007-01-01

    An extension of Drude model is proposed that accounts for spin and spin-orbit interaction of charge carriers. Spin currents appear due to combined action of the external electric field, crystal field and scattering of charge carriers. The expression for spin Hall conductivity is derived for metals and semiconductors that is independent of the scattering mechanism. In cubic metals, spin Hall conductivity $\\sigma_s$ and charge conductivity $\\sigma_c$ are related through $\\sigma_s = [2 \\pi \\hbar...

  6. Spin-Current and Spin-Splitting in Helicoidal Molecules Due to Spin-Orbit Coupling

    Science.gov (United States)

    Caetano, R. A.

    2016-03-01

    The use of organic materials in spintronic devices has been seriously considered after recent experimental works have shown unexpected spin-dependent electrical properties. The basis for the confection of any spintronic device is ability of selecting the appropriated spin polarization. In this direction, DNA has been pointed out as a potential candidate for spin selection due to the spin-orbit coupling originating from the electric field generated by accumulated electrical charges along the helix. Here, we demonstrate that spin-orbit coupling is the minimum ingredient necessary to promote a spatial spin separation and the generation of spin-current. We show that the up and down spin components have different velocities that give rise to a spin-current. By using a simple situation where spin-orbit coupling is present, we provide qualitative justifications to our results that clearly point to helicoidal molecules as serious candidates to integrate spintronic devices.

  7. Microresonators for electron spin qubits

    International Nuclear Information System (INIS)

    Suter, D.; Stonies, R.; Voges, E.

    2005-01-01

    Full text: The traditional high-Q EPR resonators are optimized for large samples. For small samples and individual qubits, it is possible to design different resonators that have much better power handling properties, create less interference with other peripheral lines and, if they are used for detection, have better sensitivity. Other parameters being equal, the sensitivity of the resonator can be increased by minimizing its size and thus increasing the filling factor. In contrast to cavity type resonators, microcoils can be made much smaller than the operation wavelength. For this type of resonator, it has been established theoretically and experimentally that the sensitivity varies inversely with its linear dimensions. Moreover, the planar coil geometry is ideal to be manufactured in a small size by means of standard microtechnology. It also offers advantages for the excitation of electron spins in prototype quantum computer systems. High microwave power to the magnetic field conversion factor of the microresonator allows to achieve 24 ns L/2 - pulses with less than 20 mW of incident power. Within the QIPDDF-ROSES project, we are using such resonators to measure the EPR parameters of monolayer molecular films of N at C60 and for excitation of the single electron spin in a defect center in diamond. The microresonator prototypes consisting of a 200 μm planar microcoil tuned and matched at 14 GHz with distributed elements have been fabricated on Si substrate. The sensitivity tests with a DPPH samples resulted in the sensitivity value 10E9 spins/G/Hz1/2 at 300 K. The designed layouts of the microresonator can be scaled down up to a tens of micrometers, and with a different microwave coupling approach hundreds of nanometers could be achieved, allowing the operation frequency up to 100 THz (author)

  8. Spinning particles in Schwarzschild space time

    International Nuclear Information System (INIS)

    Holten, J.W. van; Rietdijk, R.H.

    1992-01-01

    The motion of pseudo-classical spinning particles in a static, spherically symmetric space-time (as described by the Schwarzschild coordinate system) is analysed. The constants of motion are derived and the full set of first integrals of motion is obtained. Various types of orbits are discussed. The exact solution for planar orbits is given. (author). 13 refs.; 6 figs

  9. Where Do Spin-Offs Come From?

    DEFF Research Database (Denmark)

    Rocha, Vera; Carneiro, Anabela; Varum, Celeste

    2015-01-01

    is twofold. First, this study aims to add to our knowledge on the relationship between spin-off type and firm survival using a comprehensive matched employer-employee dataset from Portugal. After controlling for their different start-up conditions—namely regarding initial hiring schemes, business...

  10. Spin-flip transitions in magneto-optics and magneto-transport

    International Nuclear Information System (INIS)

    Zawadzki, W.

    1978-01-01

    Three-level model for InSb- and HgTe-type semiconductors is used to describe recent observations of spin-flip magnetophonon oscillations, spin-flip scattering in Shubnikov-de Haas effect, phonon- and impurity-assisted magnetooptical resonances, and resonant spin-optic-phonon interaction. (Auth.)

  11. Zeta Function Expression of Spin Partition Functions on Thermal AdS3

    Directory of Open Access Journals (Sweden)

    Floyd L.Williams

    2015-07-01

    Full Text Available We find a Selberg zeta function expression of certain one-loop spin partition functions on three-dimensional thermal anti-de Sitter space. Of particular interest is the partition function of higher spin fermionic particles. We also set up, in the presence of spin, a Patterson-type formula involving the logarithmic derivative of zeta.

  12. Genetic algorithm for minimizing the energy costs for the reorientation of the plane of the spacecraft orbit

    Directory of Open Access Journals (Sweden)

    Pankratov I.A.

    2017-09-01

    Full Text Available In the quaternion formulation, the problem of optimal reorientation of the orbital plane of a spacecraft (SC is considered. The control (acceleration from the vector of the jet thrust orthogonal to the plane of the orbit is limited in magnitude. It is necessary to minimize energy costs for the reorientation of the plane of the spacecraft orbit. An actual special case of a problem when the spacecraft orbit is circular, and control assumes constant values in certain sections of the active motion of the spacecraft is considered. An original genetic algorithm for finding the trajectories of optimal spacecraft flights is constructed. No information about the unknown initial values of the conjugate variables is required when we apply this method. Examples of the numerical solution of the problem are given for the case when the difference between the initial and final orientations of the spacecraft orbit equals to a few degrees in angular measure. In this case, the final orientation of the plane of the spacecraft orbit corresponds to the orientation of the orbital plane of the satellites of the Russian GLONASS orbital grouping.

  13. ATP-dependent Conformational Changes Trigger Substrate Capture and Release by an ECF-type Biotin Transporter.

    Science.gov (United States)

    Finkenwirth, Friedrich; Sippach, Michael; Landmesser, Heidi; Kirsch, Franziska; Ogienko, Anastasia; Grunzel, Miriam; Kiesler, Cornelia; Steinhoff, Heinz-Jürgen; Schneider, Erwin; Eitinger, Thomas

    2015-07-03

    Energy-coupling factor (ECF) transporters for vitamins and metal ions in prokaryotes consist of two ATP-binding cassette-type ATPases, a substrate-specific transmembrane protein (S component) and a transmembrane protein (T component) that physically interacts with the ATPases and the S component. The mechanism of ECF transporters was analyzed upon reconstitution of a bacterial biotin transporter into phospholipid bilayer nanodiscs. ATPase activity was not stimulated by biotin and was only moderately reduced by vanadate. A non-hydrolyzable ATP analog was a competitive inhibitor. As evidenced by cross-linking of monocysteine variants and by site-specific spin labeling of the Q-helix followed by EPR-based interspin distance analyses, closure and reopening of the ATPase dimer (BioM2) was a consequence of ATP binding and hydrolysis, respectively. A previously suggested role of a stretch of small hydrophobic amino acid residues within the first transmembrane segment of the S units for S unit/T unit interactions was structurally and functionally confirmed for the biotin transporter. Cross-linking of this segment in BioY (S) using homobifunctional thiol-reactive reagents to a coupling helix of BioN (T) indicated a reorientation rather than a disruption of the BioY/BioN interface during catalysis. Fluorescence emission of BioY labeled with an environmentally sensitive fluorophore was compatible with an ATP-induced reorientation and consistent with a hypothesized toppling mechanism. As demonstrated by [(3)H]biotin capture assays, ATP binding stimulated substrate capture by the transporter, and subsequent ATP hydrolysis led to substrate release. Our study represents the first experimental insight into the individual steps during the catalytic cycle of an ECF transporter in a lipid environment. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Optical spin generation/detection and spin transport lifetimes

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2011-01-01

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

  15. Optical spin generation/detection and spin transport lifetimes

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-02-25

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

  16. Spin Valve Systems for Angle Sensor Applications

    OpenAIRE

    Johnson, Andrew

    2004-01-01

    A contact-less sensor with the ability to measure over a 360° range has been long sought after in the automotive industry. Such a sensor could be realized by utilizing the angle dependence of the Giant Magneto Resistance (GMR) Effect in a special type of magnetic multilayer called a spin valve arranged in a wheatstone bridge circuit [Spo96]. A spin valve consists of two ferromagnetic layers separated by nonmagnetic spacer layer where the magnetization of one of the ferromagnetic layers is pin...

  17. Spin wave theory of ferrimagnetic double perovskites

    International Nuclear Information System (INIS)

    Jackeli, G.

    2004-01-01

    We present a theoretical study of magnetic properties of metallic double perovskite ferrimagnets such as Sr 2 FeMoO 6 and Sr 2 FeReO 6 . The analysis is based on the Kondo-type Hamiltonian in which charge carriers are constrained to be antiparallel to Fe local moments with spin S. The spectrum of spin wave excitations is derived based on the model Hamiltonian within the 1/S expansion. The ground state phase diagram as a function of carrier density is also discussed

  18. Thermoelectric spin voltage in graphene.

    Science.gov (United States)

    Sierra, Juan F; Neumann, Ingmar; Cuppens, Jo; Raes, Bart; Costache, Marius V; Valenzuela, Sergio O

    2018-02-01

    In recent years, new spin-dependent thermal effects have been discovered in ferromagnets, stimulating a growing interest in spin caloritronics, a field that exploits the interaction between spin and heat currents 1,2 . Amongst the most intriguing phenomena is the spin Seebeck effect 3-5 , in which a thermal gradient gives rise to spin currents that are detected through the inverse spin Hall effect 6-8 . Non-magnetic materials such as graphene are also relevant for spin caloritronics, thanks to efficient spin transport 9-11 , energy-dependent carrier mobility and unique density of states 12,13 . Here, we propose and demonstrate that a carrier thermal gradient in a graphene lateral spin valve can lead to a large increase of the spin voltage near to the graphene charge neutrality point. Such an increase results from a thermoelectric spin voltage, which is analogous to the voltage in a thermocouple and that can be enhanced by the presence of hot carriers generated by an applied current 14-17 . These results could prove crucial to drive graphene spintronic devices and, in particular, to sustain pure spin signals with thermal gradients and to tune the remote spin accumulation by varying the spin-injection bias.

  19. Electron spin-lattice relaxation in fractals

    International Nuclear Information System (INIS)

    Shrivastava, K.N.

    1986-08-01

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

  20. How does human capital affect the performance of academic spin-offs?

    OpenAIRE

    Rimestad, Mari Haga; Bjerkholt, Frøydis Folvik; Seeland, Ole Jørgen

    2014-01-01

    Article 1: Investigates the field of academic spin-offs. This type of spin-offs commercialize research results from research institutions and are believed to be a source of wealth creation. Even though academic spin-offs have high survival rates they rarely grow into high performing ventures. Furthermore, performance of young academic spin-offs is closely linked to their human capital as they often have limited resources. Through a structured literature search we investigated how different ty...

  1. Noise in tunneling spin current across coupled quantum spin chains

    Science.gov (United States)

    Aftergood, Joshua; Takei, So

    2018-01-01

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

  2. Overview of spin physics

    Energy Technology Data Exchange (ETDEWEB)

    Yokosawa, A.

    1992-12-23

    Spin physics activities at medium and high energies became significantly active when polarized targets and polarized beams became accessible for hadron-hadron scattering experiments. My overview of spin physics will be inclined to the study of strong interaction using facilities at Argonne ZGS, Brookhaven AGS (including RHIC), CERN, Fermilab, LAMPF, an SATURNE. In 1960 accelerator physicists had already been convinced that the ZGS could be unique in accelerating a polarized beam; polarized beams were being accelerated through linear accelerators elsewhere at that time. However, there was much concern about going ahead with the construction of a polarized beam because (i) the source intensity was not high enough to accelerate in the accelerator, (ii) the use of the accelerator would be limited to only polarized-beam physics, that is, proton-proton interaction, and (iii) p-p elastic scattering was not the most popular topic in high-energy physics. In fact, within spin physics, [pi]-nucleon physics looked attractive, since the determination of spin and parity of possible [pi]p resonances attracted much attention. To proceed we needed more data beside total cross sections and elastic differential cross sections; measurements of polarization and other parameters were urgently needed. Polarization measurements had traditionally been performed by analyzing the spin of recoil protons. The drawbacks of this technique are: (i) it involves double scattering, resulting in poor accuracy of the data, and (ii) a carbon analyzer can only be used for a limited region of energy.

  3. Storing quantum information in spins and high-sensitivity ESR

    Science.gov (United States)

    Morton, John J. L.; Bertet, Patrice

    2018-02-01

    Quantum information, encoded within the states of quantum systems, represents a novel and rich form of information which has inspired new types of computers and communications systems. Many diverse electron spin systems have been studied with a view to storing quantum information, including molecular radicals, point defects and impurities in inorganic systems, and quantum dots in semiconductor devices. In these systems, spin coherence times can exceed seconds, single spins can be addressed through electrical and optical methods, and new spin systems with advantageous properties continue to be identified. Spin ensembles strongly coupled to microwave resonators can, in principle, be used to store the coherent states of single microwave photons, enabling so-called microwave quantum memories. We discuss key requirements in realising such memories, including considerations for superconducting resonators whose frequency can be tuned onto resonance with the spins. Finally, progress towards microwave quantum memories and other developments in the field of superconducting quantum devices are being used to push the limits of sensitivity of inductively-detected electron spin resonance. The state-of-the-art currently stands at around 65 spins per √{ Hz } , with prospects to scale down to even fewer spins.

  4. Photonic spin Hall effect in metasurfaces: a brief review

    Directory of Open Access Journals (Sweden)

    Liu Yachao

    2016-07-01

    Full Text Available The photonic spin Hall effect (SHE originates from the interplay between the photon-spin (polarization and the trajectory (extrinsic orbital angular momentum of light, i.e. the spin-orbit interaction. Metasurfaces, metamaterials with a reduced dimensionality, exhibit exceptional abilities for controlling the spin-orbit interaction and thereby manipulating the photonic SHE. Spin-redirection phase and Pancharatnam-Berry phase are the manifestations of spin-orbit interaction. The former is related to the evolution of the propagation direction and the latter to the manipulation with polarization state. Two distinct forms of splitting based on these two types of geometric phases can be induced by the photonic SHE in metasurfaces: the spin-dependent splitting in position space and in momentum space. The introduction of Pacharatnam-Berry phases, through space-variant polarization manipulations with metasurfaces, enables new approaches for fabricating the spin-Hall devices. Here, we present a short review of photonic SHE in metasurfaces and outline the opportunities in spin photonics.

  5. Storing quantum information in spins and high-sensitivity ESR.

    Science.gov (United States)

    Morton, John J L; Bertet, Patrice

    2018-02-01

    Quantum information, encoded within the states of quantum systems, represents a novel and rich form of information which has inspired new types of computers and communications systems. Many diverse electron spin systems have been studied with a view to storing quantum information, including molecular radicals, point defects and impurities in inorganic systems, and quantum dots in semiconductor devices. In these systems, spin coherence times can exceed seconds, single spins can be addressed through electrical and optical methods, and new spin systems with advantageous properties continue to be identified. Spin ensembles strongly coupled to microwave resonators can, in principle, be used to store the coherent states of single microwave photons, enabling so-called microwave quantum memories. We discuss key requirements in realising such memories, including considerations for superconducting resonators whose frequency can be tuned onto resonance with the spins. Finally, progress towards microwave quantum memories and other developments in the field of superconducting quantum devices are being used to push the limits of sensitivity of inductively-detected electron spin resonance. The state-of-the-art currently stands at around 65 spins per Hz, with prospects to scale down to even fewer spins. Copyright © 2017. Published by Elsevier Inc.

  6. Dizziness and Balance Problems in Kids: Spinning Sensations and Unsteadiness

    Science.gov (United States)

    ... is spinning or moving—a condition known as vertigo. Other symptoms can include blurred vision, vomiting, diarrhea, ... Are Proteins in Formula Linked to Type 1 Diabetes? Sound Health Reducing Children’s Chances of Asthma Wise ...

  7. Quantum spin transistor with a Heisenberg spin chain

    Science.gov (United States)

    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

  8. Spinning fluids reactor

    Science.gov (United States)

    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.

  9. Spin gating electrical current

    Science.gov (United States)

    Ciccarelli, C.; Zârbo, L. P.; Irvine, A. C.; Campion, R. P.; Gallagher, B. L.; Wunderlich, J.; Jungwirth, T.; Ferguson, A. J.

    2012-09-01

    The level of the chemical potential is a fundamental parameter of the electronic structure of a physical system, which consequently plays an important role in defining the properties of active electrical devices. We directly measure the chemical potential shift in the relativistic band structure of the ferromagnetic semiconductor (Ga,Mn)As, controlled by changes in its magnetic order parameter. Our device comprises a non-magnetic aluminum single electron channel capacitively coupled to the (Ga,Mn)As gate electrode. The chemical potential shifts of the gate are directly read out from the shifts in the Coulomb blockade oscillations of the single electron transistor. The experiments introduce a concept of spin gating electrical current. In our spin transistor spin manipulation is completely removed from the electrical current carrying channel.

  10. SPIN-selling

    CERN Document Server

    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.

  11. Chiral higher spin gravity

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2017-06-01

    We construct a candidate for the most general chiral higher spin theory with AdS3 boundary conditions. In the Chern-Simons language, on the left it has the Drinfeld-Sokolov reduced form, but on the right all charges and chemical potentials are turned on. Altogether (for the spin-3 case) these are 19 functions. Despite this, we show that the resulting metric has the form of the "most general" AdS3 boundary conditions discussed by Grumiller and Riegler. The asymptotic symmetry algebra is a product of a W3 algebra on the left and an affine s l (3 )k current algebra on the right, as desired. The metric and higher spin fields depend on all the 19 functions. We compare our work with previous results in the literature.

  12. Spin Waves in Terbium

    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...

  13. A review on organic spintronic materials and devices: II. Magnetoresistance in organic spin valves and spin organic light emitting diodes

    Directory of Open Access Journals (Sweden)

    Rugang Geng

    2016-09-01

    Full Text Available In the preceding review paper, Paper I [Journal of Science: Advanced Materials and Devices 1 (2016 128–140], we showed the major experimental and theoretical studies on the first organic spintronic subject, namely organic magnetoresistance (OMAR in organic light emitting diodes (OLEDs. The topic has recently been of renewed interest as a result of a demonstration of the magneto-conductance (MC that exceeds 1000% at room temperature using a certain type of organic compounds and device operating condition. In this report, we will review two additional organic spintronic devices, namely organic spin valves (OSVs where only spin polarized holes exist to cause magnetoresistance (MR, and spin organic light emitting diodes (spin-OLEDs where both spin polarized holes and electrons are injected into the organic emissive layer to form a magneto-electroluminescence (MEL hysteretic loop. First, we outline the major advances in OSV studies for understanding the underlying physics of the spin transport mechanism in organic semiconductors (OSCs and the spin injection/detection at the organic/ferromagnet interface (spinterface. We also highlight some of outstanding challenges in this promising research field. Second, the first successful demonstration of spin-OLEDs is reviewed. We also discuss challenges to achieve the high performance devices. Finally, we suggest an outlook on the future of organic spintronics by using organic single crystals and aligned polymers for the spin transport layer, and a self-assembled monolayer to achieve more controllability for the spinterface.

  14. Spin flexoelectricity and chiral spin structures in magnetic films

    OpenAIRE

    Pyatakov, A. P.; Sergeev, A. S.; Mikailzade, F. A.; Zvezdin, A. K.

    2015-01-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism is discussed. The phenomenological arguments bas...

  15. Spinning geodesic Witten diagrams

    International Nuclear Information System (INIS)

    Dyer, Ethan; Freedman, Daniel Z.; Massachusetts Institute of Technology; Massachusetts Institute of Technology; Sully, James; McGill University, Montreal, QC

    2017-01-01

    We present an expression for the four-point conformal blocks of symmetric traceless operators of arbitrary spin as an integral over a pair of geodesics in Anti-de Sitter space, generalizing the geodesic Witten diagram formalism of Hijano et al. to arbitrary spin. As an intermediate step in the derivation, we identify a convenient basis of bulk threepoint interaction vertices which give rise to all possible boundary three point structures. Lastly, we highlight a direct connection between the representation of the conformal block as geodesic Witten diagram and the shadow operator formalism.

  16. Spin gating electrical current

    Czech Academy of Sciences Publication Activity Database

    Ciccarelli, C.; Zarbo, Liviu; Irvine, A.C.; Campion, R. P.; Gallagher, B. L.; Wunderlich, Joerg; Jungwirth, Tomáš; Ferguson, A.J.

    2012-01-01

    Roč. 101, č. 12 (2012), , , "122411-1"-"122411-4" ISSN 0003-6951 R&D Projects: GA AV ČR KJB100100802; GA AV ČR KAN400100652 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic resonance * spin-orbit coupling * nanodevices Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.794, year: 2012 http://arxiv.org/abs/1203.2439

  17. Spin echo in synchrotrons

    Directory of Open Access Journals (Sweden)

    Alexander W. Chao

    2007-01-01

    Full Text Available 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 Δν_{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 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 Δν_{spin} 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

  18. Spin, gravity, and inertia.

    Science.gov (United States)

    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.

  19. Measurement of the spin asymmetry of the beam in the polarized virtual Compton scattering on the proton. Study of the nucleon's energy spectra through the QCD-type potential model; Mesure de l'asymetrie de spin de faisceau en diffusion compton virtuelle polarisee sur le proton. Etude du spectre d'energie du nucleon par le modele de potentiel de type QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bensafa, I.K

    2006-05-15

    The first part of this work presents the analysis and results of the VCS-SSA (virtual Compton scattering - single spin asymmetry) experiment at MAMI (Mainz). It was carried out with beam energy 883 MeV and longitudinal polarization (about 80%), at virtual photon four-momentum transfer squared (Q{sup 2} = 0.35 GeV{sup 2}) to measure the beam asymmetry in the ep {yields} ep{gamma} and ep {yields} ep{pi}{sup 0} reactions. The asymmetry obtained in photon (resp. pion) electro-production is between 0-15% (resp. 0-2%). The dispersion relation model for virtual Compton scattering and MAID model (for {pi}{sup 0}) reproduce the amplitude globally but not completely the shape of the asymmetry. Perhaps this discrepancy is due to an imperfect parameterization of some pion production multipoles ({gamma}{sup *}N {yields} {pi}N). The second part is dedicated to the study of the nucleon energy spectrum in ground-state L=0 and excited-state L=1 in the quark model, using the Coulomb + linear potential type (CL) and a relativistic correction. The hyperfine correction is applied to discriminate the nucleon masses. The values of the mass found for the proton and the {delta}(1232) are respectively equal to (968 MeV, 1168 MeV), and the masses of the excited states are between 1564 - 1607 MeV. This part is completed by an application of the CL model to an approximate calculation of generalized polarizabilities of the proton. (author)

  20. Classical description of dynamical many-body systems with central forces, spin-orbit forces and spin-spin forces

    International Nuclear Information System (INIS)

    Goepfert, A.

    1994-01-01

    This thesis develops a new model, and related numerical methods, to describe classical time-dependent many-body systems interacting through central forces, spin-orbit forces and spin-spin forces. The model is based on two-particle interactions. The two-body forces consist of attractive and repulsive parts. In this model the investigated multi-particle systems are self-bound. Also the total potential of the whole ensemble is derived from the two-particle potential and is not imposed 'from outside'. Each particle has the three degrees of freedom of its centre-of-mass motion and the spin degree of freedom. The model allows for the particles to be either charged or uncharged. Furthermore, each particle has an angular momentum, an intrinsic spin, and a magnetic dipole moment. Through the electromagnetic forces between these charges and moments there arise dynamical couplings between them. The internal interactions between the charges and moments are well described by electromagnetic coupling mechanisms. In fact, compared to conventional classical molecular dynamics calculations in van der Waals clusters, which have no spin degrees of freedom, or for Heisenberg spin Systems, which have no orbital degrees of freedom, the model presented here contains both types of degrees of freedom with a highly non-trivial coupling. The model allows to study the fundamental effects resulting from the dynamical coupling of the spin and the orbital-motion sub-systems. In particular, the dynamics of the particle mass points show a behaviour basically different from the one of particles in a potential with only central forces. Furthermore, a special type of quenching procedure was invented, which tends to drive the multi-particle Systems into states with highly periodic, non-ergodic behaviour. Application of the model to cluster simulations has provided evidence that the model can also be used to investigate items like solid-to-liquid phase transitions (melting), isomerism and specific heat

  1. A stochastic picture of spin

    International Nuclear Information System (INIS)

    Faris, W.G.

    1981-01-01

    Dankel has shown how to incorporate spin into stochastic mechanics. The resulting non-local hidden variable theory gives an appealing picture of spin correlation experiments in which Bell's inequality is violated. (orig.)

  2. Polarization of emission from asymmetric rotors. II. Vector reorientation through intramolecular coupling and inelastic collisions

    Science.gov (United States)

    Truhins, Kaspars; McCaffery, Anthony J.; Alwahabi, Zeyad T.; Rawi, Zaid

    1997-07-01

    We report measurements of the linear and circular polarization ratios from fully resolved rotational levels of the asymmetric rotor NH2 populated by collisions with H atoms. The results compare well with a theoretical model that includes the depolarizing effects of intramolecular coupling of rotational angular momentum N to nuclear and to electron spin. These have a very significant influence on fluorescence polarization. The model also incorporates the tilting of the N vector in the molecule frame that occurs when inter-k stack transitions take place. Changes in N vector orientation are described with the aid of the angular momentum sphere, a classical representation of the motion of the N vector in a molecule fixed frame. The theoretical treatment assumes the classically impulsive limit for the collisional interaction with conservation of the m quantum number along the kinematic apse. This description of the fate of the N vector under the influence of intra- and intermolecular interactions allows stereodynamical conclusions to be drawn from experimental observations of fluorescence polarization.

  3. Antiferromagnetic spin-orbitronics

    KAUST Repository

    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.

  4. " The Story of Spin

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 11. The Story of Spin - From Spectroscopy to Relativistic Quantum Mechanics. N Mukunda. Book Review Volume 3 Issue 11 November 1998 pp 89-90. Fulltext. Click here to view fulltext PDF. Permanent link:

  5. Spin and isospin modes

    International Nuclear Information System (INIS)

    Suzuki, T.; Sagawa, H.

    2000-01-01

    Complete text of publication follows. Spin and isospin modes in nuclei are investigated. We discuss some of the following topics. 1. Spin-dipole excitations in 12 C and 16 O are studied (1). Effects of tensor and spin-orbit interactions on the distribution of the strengths are investigated, and neutral current neutrino scattering cross sections in 16 O are obtained for heavy-flavor neutrinos from the supernovae. 2. Gamow-Teller (GT) and spin-dipole (SD) modes in 208 Bi are investigated. Quenching and fragmentation of the GT strength are discussed (2). SD excitations and electric dipole (E1) transitions between the GT and SD states are studied (3). Calculated E1 strengths are compared with the sum rule values obtained within the 1p-1h and 1p-1h + 2p-2h configuration spaces. 3. Coulomb displacement energy (CDE) of the IAS of 14 Be is calculated, and the effects of the halo on the CDE and the configuration of the halo state are investigated. 4. Spreading width of IAS and isospin dependence of the width are investigated (4). Our formula for the width explains very well the observed isospin dependence (5). (author)

  6. On "spinning" membrane models

    NARCIS (Netherlands)

    Bergshoeff, E.; Sezgin, E.; Townsend, P.K.

    1988-01-01

    Several alternative actions for a bosonic membrane have recently been proposed. We show that a linearly realized locally world-volume-supersymmetric (spinning membrane) extension of any of these actions implies an analogous extension of the standard Dirac membrane action. We further show that a

  7. Nuclear spin-off

    International Nuclear Information System (INIS)

    1981-11-01

    This booklet gives examples of 'nuclear spin off', from research programmes carried out for the UKAEA, under the following headings; non destructive testing; tribology; environmental protection; flow measurement; material sciences; mechanical engineering; marine services; biochemical technology; electronic instrumentation. (U.K.)

  8. The invariance of spin

    International Nuclear Information System (INIS)

    Bramson, B.D.

    1978-01-01

    An isolated system in general relativity makes a transition between stationary states. It is shown that the spin vectors of the system, long before and long after the emission of radiation, are supertranslation invariant and, hence, independent of the choice of Minkowski observation space. (author)

  9. [The Rockefeller Foundation and its efforts toward a reorientation of German medicine and public health in the 1950s].

    Science.gov (United States)

    Schleiermacher, Sabine

    2010-01-01

    The Rockefeller Foundation invested substantial funds into promoting the development of public health as a discipline and a re-orientation of medical training in West Germany to support the democratization of German society. Not limiting itself to the simple provision of literature, the Foundation pursued a two-pronged strategy. Firstly, the Foundation organized a program for German university physicians and public health officers to visit various universities and teaching hospitals in the USA and Canada. A second aim was to establish training institutes for postgraduate physicians. However, rather than simply imposing the US model, the Foundation intended to adapt it to the German context, in the form of a postgraduate course for physicians that integrated practical experience with a university setting. My research to date shows that the Foundation's activities did not meet with much enthusiasm from German medical professionals. Intellectual, cultural, cognitive and political differences impaired constructive collaboration between the Foundation's staff and local practitioners and academics.

  10. A Framework for the Development of Automatic DFA Method to Minimize the Number of Components and Assembly Reorientations

    Science.gov (United States)

    Alfadhlani; Samadhi, T. M. A. Ari; Ma’ruf, Anas; Setiasyah Toha, Isa

    2018-03-01

    Assembly is a part of manufacturing processes that must be considered at the product design stage. Design for Assembly (DFA) is a method to evaluate product design in order to make it simpler, easier and quicker to assemble, so that assembly cost is reduced. This article discusses a framework for developing a computer-based DFA method. The method is expected to aid product designer to extract data, evaluate assembly process, and provide recommendation for the product design improvement. These three things are desirable to be performed without interactive process or user intervention, so product design evaluation process could be done automatically. Input for the proposed framework is a 3D solid engineering drawing. Product design evaluation is performed by: minimizing the number of components; generating assembly sequence alternatives; selecting the best assembly sequence based on the minimum number of assembly reorientations; and providing suggestion for design improvement.

  11. Implementation of a Basic Package of Oral Care: towards a reorientation of dental Ngos and their volunteers.

    Science.gov (United States)

    Helderman, Wim van Palenstein; Benzian, Habib

    2006-02-01

    Dental NGOs and volunteers working in disadvantaged communities around the world do so with the best of intentions and with high motivation. Regrettably, the impact of this engagement on oral health at the population level remains rather low. This is mainly due to the choice of inappropriate approaches, the failure to integrate their projects within existing health care systems and the lack of sustainability. This paper proposes the concept of the Basic Package of Oral Care (BPOC) as a guiding framework for dental NGO and volunteer activities. The main components of the BPOC (Oral Urgent Treatment, Affordable Fluoride Toothpaste, Atraumatic Restorative Treatment) offer many opportunities for effective, affordable and sustainable activities that aim to improve oral health on the community and population level. Only through a reorientation of dental volunteer services and NGOs towards new roles and activities can a sustained impact on global oral health be possible. Recommendations are given that could help dental NGOs and volunteers in this process of change.

  12. Nematicons and Their Electro-Optic Control: Light Localization and Signal Readdressing via Reorientation in Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Armando Piccardi

    2013-10-01

    Full Text Available Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely “nematicons”. Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

  13. Nematicons and their electro-optic control: light localization and signal readdressing via reorientation in liquid crystals.

    Science.gov (United States)

    Piccardi, Armando; Alberucci, Alessandro; Assanto, Gaetano

    2013-10-08

    Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely "nematicons". Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

  14. Tunneling reorientation and stress and electric field induced alignment of the V- center in MgO

    International Nuclear Information System (INIS)

    Rius, G.; Herve, A.

    1975-01-01

    Stress and electric field induced alignments of the V - center in MgO were measured in the range 2.1 to 77K by observing the changes in intensity of the ESR lines. A preferential alignment is produced parallel to the applied stress or electric field, showing that the defect reorientates between the different distorted configurations even at liquid helium temperature. The elastic dipole moment μ and the electric dipole moment p were measured at 77K for stresses up to 1500kg/cm 2 and fields up to 200kV.cm -1 : μ=(9.6+-0.4)10 -3 K kg -1 cm 2 and p=(3.7+-0.1)10 -4 K V -1 cm, that is p=3.2+-0.1eA (symbol A is for Angstroems) [fr

  15. 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.

  16. Spin transport in graphene nanostructures

    NARCIS (Netherlands)

    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

  17. Spin Transport in Bose Gases

    NARCIS (Netherlands)

    van Driel, H.J.

    2012-01-01

    In this Thesis, we show that in a rotating two-component Bose mixture, the spin drag between the two different spin species shows a Hall effect. This spin drag Hall effect can be observed experimentally by studying the out-of-phase dipole mode of the mixture. We determine the damping of this mode

  18. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    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.

  19. Spin mapping at the nanoscale and atomic scale

    Science.gov (United States)

    Wiesendanger, Roland

    2009-10-01

    The direct observation of spin structures with atomic-scale resolution, a long-time dream in condensed matter research, recently became a reality based on the development of spin-sensitive scanning probe methods, such as spin-polarized scanning-tunneling microscopy (SP-STM) and magnetic exchange force microscopy (MExFM). This article reviews the basic principles and methods of SP-STM and MExFM and describes recently achieved milestones in the application of these techniques to metallic and electrically insulating magnetic nanostructures. Discoveries of novel types of magnetic order at the nanoscale are presented as well as challenges for the future, including studies of local spin excitations based on spin-resolved inelastic tunneling spectroscopy and measurements of damping forces in MExFM experiments.

  20. Spinning Them Off: Entrepreneuring Practices in Corporate Spin-Offs

    Directory of Open Access Journals (Sweden)

    Katja Maria Hydle

    2016-01-01

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

  1. Spin flexoelectricity and chiral spin structures in magnetic films

    Science.gov (United States)

    Pyatakov, A. P.; Sergeev, A. S.; Mikailzade, F. A.; Zvezdin, A. K.

    2015-06-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism are discussed. The phenomenological arguments based on the geometrical idea of curvature-induced effects are supported by analysis of the microscopic mechanisms of spin flexoelectricity based on three-site ion indirect exchange and twisted RKKY interaction models.

  2. Modeling the effects of structure and dynamics of the nitroxide side chain on the ESR spectra of spin-labeled proteins.

    Science.gov (United States)

    Tombolato, Fabio; Ferrarini, Alberta; Freed, Jack H

    2006-12-28

    In the companion paper (J. Phys. Chem. B 2006, 110, jp0629487), a study of the conformational dynamics of methanethiosulfonate spin probes linked at a surface-exposed alpha-helix has been presented. Here, on the basis of this analysis, X-band ESR spectra of these spin labels are simulated within the framework of the Stochastic Liouville equation (SLE) methodology. Slow reorientations of the whole protein are superimposed on fast chain motions, which have been identified with conformational jumps and fluctuations in the minima of the chain torsional potential. Fast chain motions are introduced in the SLE for the protein reorientations through partially averaged magnetic tensors and relaxation times calculated according to the motional narrowing theory. The 72R1 and 72R2 mutants of T4 lysozyme, which bear the spin label at a solvent-exposed helix site, have been taken as test systems. For the side chain of the R2 spin label, only a few noninterconverting conformers are possible, whose mobility is limited to torsional fluctuations, yielding almost identical spectra, typical of slightly mobile nitroxides. In the case of R1, more complex spectra result from the simultaneous presence of constrained and mobile chain conformers, with relative weights that can depend on the local environment. The model provides an explanation for the experimentally observed dependence of the spectral line shapes on temperature, solvent, and pattern of substituents in the pyrroline ring. The relatively simple methodology presented here allows the introduction of realistic features of the spin probe dynamics into the simulation of ESR spectra of spin-labeled proteins; moreover, it provides suggestions for a proper account of such dynamics in more sophisticated approaches.

  3. Spin-diffusions and diffusive molecular dynamics

    Science.gov (United States)

    Farmer, Brittan; Luskin, Mitchell; Plecháč, Petr; Simpson, Gideon

    2017-12-01

    Metastable configurations in condensed matter typically fluctuate about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of classical molecular dynamics (MD) methods and has spurned the development of a host of approximate algorithms. One recently proposed method is diffusive MD which aims at integrating a system of ordinary differential equations describing the likelihood of occupancy by one of two species, in the case of a binary alloy, while quasistatically evolving the locations of the atoms. While diffusive MD has shown itself to be efficient and provide agreement with observations, it is fundamentally a model, with unclear connections to classical MD. In this work, we formulate a spin-diffusion stochastic process and show how it can be connected to diffusive MD. The spin-diffusion model couples a classical overdamped Langevin equation to a kinetic Monte Carlo model for exchange amongst the species of a binary alloy. Under suitable assumptions and approximations, spin-diffusion can be shown to lead to diffusive MD type models. The key assumptions and approximations include a well-defined time scale separation, a choice of spin-exchange rates, a low temperature approximation, and a mean field type approximation. We derive several models from different assumptions and show their relationship to diffusive MD. Differences and similarities amongst the models are explored in a simple test problem.

  4. Spin Superfluidity and Magnone BEC in He-3

    Science.gov (United States)

    Bunkov, Yury

    2011-03-01

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

  5. Excitation of coherent propagating spin waves by pure spin currents.

    Science.gov (United States)

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

    2016-01-28

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

  6. Spin-wave-induced spin torque in Rashba ferromagnets

    Science.gov (United States)

    Umetsu, Nobuyuki; Miura, Daisuke; Sakuma, Akimasa

    2015-05-01

    We study the effects of Rashba spin-orbit coupling on the spin torque induced by spin waves, which are the plane-wave dynamics of magnetization. The spin torque is derived from linear-response theory, and we calculate the dynamic spin torque by considering the impurity-ladder-sum vertex corrections. This dynamic spin torque is divided into three terms: a damping term, a distortion term, and a correction term for the equation of motion. The distorting torque describes a phenomenon unique to the Rashba spin-orbit coupling system, where the distorted motion of magnetization precession is subjected to the anisotropic force from the Rashba coupling. The oscillation mode of the precession exhibits an elliptical trajectory, and the ellipticity depends on the strength of the nesting effects, which could be reduced by decreasing the electron lifetime.

  7. Reorientational motion of a cross-link junction in a poly(dimethylsiloxane) network measured by time-resolved fluorescence depolarization

    International Nuclear Information System (INIS)

    Stein, A.D.; Hoffman, D.A.; Frank, C.W.; Fayer, M.D.

    1992-01-01

    The reorientational dynamics of a cross-link junction in poly(dimethylsiloxane) networks, measured by the fluorescence anisotropy decay of a chromophore tagged to the cross-link, have been investigated over a range of temperatures from T g +75 to T g +150. The probe chromophore, 1-dimethylamino-5-sulfonylnaphthalene amide (dansyl amide), is pendant to a trifunctional silane that acts as a cross-linking molecule. In cyclohexanol, the fluorescence anisotropy decay is in agreement with Debye--Stokes--Einstein hydrodynamic theory (rotational diffusion) demonstrating that the cross-linker can be used as a probe of orientational relaxation. The fluorescence anisotropy decays at a rapid rate in an end-linked poly(dimethyl siloxane) network reflecting fast reorientational motion of the cross-link junction. This reorientation appears diffusive and has a temperature dependence in accord with the Williams--Landel--Ferry equation. A model is proposed that suggests that reorientation and translational motion of the cross-link occur simultaneously and are both coupled to fluctuations of the polymer chain ends

  8. Electron probe X-ray microanalysis studies on the distribution change of intra- and extracellular calcium in the elongation zone of horizontally reoriented soybean roots

    International Nuclear Information System (INIS)

    Hayatsu, Manabu; Suzuki, Suechika

    2015-01-01

    To clarify the contribution of Ca to the gravitropic response, quantitative X-ray microanalyses were performed on cryosections of roots of soybean seedlings reoriented horizontally from their original vertical orientation. After reorientation, the roots bent gradually toward the ground at the elongation zone. The concentrations of Ca in the cell walls, cytoplasmic matrices and central vacuoles of cortical cells were measured in the upper and lower halves of the elongation zone at 0, 30, 60 and 120 min after reorientation. The Ca concentration did not significantly change in the cytoplasmic matrices or vacuoles. Additionally, the Ca concentration did not change significantly in cell walls at 30 min after reorientation; however, beyond 30 min, this concentration significantly increased gradually in the lower half of the elongation zone and decreased in the upper half of the elongation zone, indicating a typical asymmetrical distribution of Ca. These results suggest that Ca moves apoplastically in soybean roots to produce an asymmetrical Ca distribution in the elongation zone, which contributes to root curvature. The possible role of Ca in accelerating or repressing the effect of auxin is also discussed in this study. (author)

  9. Three-electron spin qubits

    Science.gov (United States)

    Russ, Maximilian; Burkard, Guido

    2017-10-01

    The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby completing the list of requirements for quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange

  10. Determination of the spin diffusion length in germanium by spin optical orientation and electrical spin injection

    Science.gov (United States)

    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.

  11. Spin diffusion length of Permalloy using spin absorption in lateral spin valves

    Science.gov (United States)

    Sagasta, Edurne; Omori, Yasutomo; Isasa, Miren; Otani, YoshiChika; Hueso, Luis E.; Casanova, Fèlix

    2017-08-01

    We employ the spin absorption technique in lateral spin valves to extract the spin diffusion length of Permalloy (Py) as a function of temperature and resistivity. A linear dependence of the spin diffusion length with the conductivity of Py is observed, evidencing that the Elliott-Yafet mechanism is the dominant spin relaxation mechanism in Permalloy. Completing the dataset with additional data found in the literature, we obtain λPy = (0.91 ± 0.04) (fΩm2)/ρPy.

  12. Muon spin rotation studies

    Science.gov (United States)

    1984-01-01

    The bulk of the muon spin rotation research work centered around the development of the muon spin rotation facility at the Alternating Gradient Synchrotron (AGS) of Brookhaven National Laboratory (BNL). The collimation system was both designed and fabricated at Virginia State University. This improved collimation system, plus improvements in detectors and electronics enabled the acquisition of spectra free of background out to 15 microseconds. There were two runs at Brookhaven in 1984, one run was devoted primarily to beam development and the other run allowed several successful experiments to be performed. The effect of uniaxial strain on an Fe(Si) crystal at elevated temperature (360K) was measured and the results are incorporated herein. A complete analysis of Fe pulling data taken earlier is included.

  13. Spin and Madelung fluid

    International Nuclear Information System (INIS)

    Salesi, G.

    1995-07-01

    Starting from the Pauli current the decomposition of the non-relativistic local velocity has been obtained in two parts (in the ordinary tensorial language): one parallel and the other orthogonal to the impulse. The former is recognized to be the classical part, that is, the center-of-mass (CM) velocity, and the latter the quantum one, that is, the velocity of the motion in the CM frame (namely, the internal spin motion or Zitterbewegung). Inserting this complete, composite expression of the velocity into the kinetic energy term of the classical non-relativistic (i.e. Newtonian) Lagrangian, the author straightforwardly get the appearance of the so called quantum potential associates as it is known, to the Madelung fluid. In such a way, the quantum mechanical behaviour of particles appears to be strictly correlated to the existence of spin and Zitterbewegung

  14. Relaxations in spin glasses: Similarities and differences from ordinary glasses

    International Nuclear Information System (INIS)

    Ngai, K.L.; Rajagopal, A.K.; Huang, C.Y.

    1984-01-01

    Relaxation phenomena have become a major concern in the physics of spin glasses. There are certain resemblances of these relaxation properties to those of ordinary glasses. In this work, we compare the relaxation properties of spin glasses near the freezing temperature with those of glasses near the glass transition temperature. There are similarities between the two types of glasses. Moreover, the relaxation properties of many glasses and spin glasses are in conformity with two coupled ''universality'' relations predicted by a recent model of relaxations in condensed matter

  15. Markov chain analysis of single spin flip Ising simulations

    International Nuclear Information System (INIS)

    Hennecke, M.

    1997-01-01

    The Markov processes defined by random and loop-based schemes for single spin flip attempts in Monte Carlo simulations of the 2D Ising model are investigated, by explicitly constructing their transition matrices. Their analysis reveals that loops over all lattice sites using a Metropolis-type single spin flip probability often do not define ergodic Markov chains, and have distorted dynamical properties even if they are ergodic. The transition matrices also enable a comparison of the dynamics of random versus loop spin selection and Glauber versus Metropolis probabilities

  16. Pangaea, She No Spin

    Science.gov (United States)

    McDowell, M.

    2002-12-01

    Looking at lopsided Pangaea, shown imaginatively on many illustrated proposals, I wondered what would happen if the configuration were put in high relief on a globe and spun on axis. Then I wondered if the present configuration of land masses would itself balance as a spinning top. So I got two Replogle globes, two boxes of colored modeling clay sticks, and two fat knitting needles, to fit through the capped holes at the poles of the globes. The clay sticks I cut up into 3 mm. (1/8") slices, using a different color for each continent, and applied to the first globe, assuming the extreme exaggeration above the geoid, no matter how crude, would tell the story. Inserting one needle through the globe and securing it, I balanced the globe on the point of the needle and twirled it like a top. Result: Wobbly! Top end of needle gyrated unevenly, and here it was supposed to make a smooth precessional cone. Oh boy. For the second globe, I used a Scotese "free stuff" interpretation of Pangaea, which I had to augment considerably using USGS, DuToit, Irving and other references, fitting it on the globe and applying identical clay color slices to what I judged generally accepted land surfaces. Result: the thing would hardly stand up, let alone spin. Conclusion: Although a refinement of application on the "today" globe might eliminate nutation, creating a smoother spin, there is no way any refinement of Pangaea on the same size globe can come close. While the concept of a supercontinent may be viable, I theorize that it had to have evolved on a far smaller globe, where land mass could balance, and the "breakup" would not have caused us to wildly gyrate on our axis. Because Pangaea, she no spin.

  17. Spin Hall effect

    Czech Academy of Sciences Publication Activity Database

    Sinova, Jairo; Valenzuela, O.V.; Wunderlich, Joerg; Back, C.H.; Jungwirth, Tomáš

    2015-01-01

    Roč. 87, č. 4 (2015), s. 1213-1259 ISSN 0034-6861 R&D Projects: GA MŠk(CZ) LM2011026; GA ČR GB14-37427G EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : spin Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 33.177, year: 2015

  18. Spin and gravitation

    Science.gov (United States)

    Ray, J. R.

    1982-01-01

    The fundamental variational principle for a perfect fluid in general relativity is extended so that it applies to the metric-torsion Einstein-Cartan theory. Field equations for a perfect fluid in the Einstein-Cartan theory are deduced. In addition, the equations of motion for a fluid with intrinsic spin in general relativity are deduced from a special relativistic variational principle. The theory is a direct extension of the theory of nonspinning fluids in special relativity.

  19. Spinning out a star.

    Science.gov (United States)

    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.

  20. Spin Propensities of Octahedral Complexes From Density Functional Theory

    DEFF Research Database (Denmark)

    Mortensen, Sara R.; Kepp, Kasper Planeta

    2015-01-01

    The fundamental balance between high- and low-spin states of transition metal systems depends on both the metal ion and the ligands surrounding it, as often visualized by the spectrochemical series. Most density functionals do not reproduce this balance, and real spin state propensities depend...... on orbital pairing and vibrational entropies absent in the spectrochemical series. Thus, we systematically computed the tendency toward high or low spin of "text-book" octahedral metal complexes versus ligand and metal type, using eight density functionals. Dispersion effects were generally ... assessment of spin state propensities versus ligand and metal type and reveal, e.g., that CN- is consistently weaker than CO for M(II) but stronger than CO for M(III) and SCN- and NCS- change order in M(II) versus M(III) complexes. Contrary to expectation based on the spectrochemical series, Cl- and Br...

  1. Spinning geometry = Twisted geometry

    International Nuclear Information System (INIS)

    Freidel, Laurent; Ziprick, Jonathan

    2014-01-01

    It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space. (paper)

  2. Spin Foam Models

    CERN Document Server

    Krasnov, K V

    1999-01-01

    The term ‘spin foam models’ was invented only a couple years ago by Baez to refer to a new approach to quantization of general relativity that appeared as an offsping of loop quantum gravity. Although this new approach was motivated, both logically and historically, by loop quantum gravity, it became clear by now that the two approaches are rather independent. While loop quantum gravity attempts to give a canonical quantization of general relativity, spin foam model approach is set to make sense of the path integral for gravity. Eventually, the two approaches will probably be shown to be equivalent, but no rigorous result to this effect exists as for now. In this thesis I develop the spin foam quantization of gravity from scratch, referring to results from loop quantum gravity only for comparison. I start from a review of 2 + 1 gravity and discuss different roots to quantize it. While some of them, as, for example, using Chern-Simons theory, only exist in 2 + 1, others can be generalized t...

  3. Nonadiabatic generation of spin currents in a quantum ring with Rashba and Dresselhaus spin-orbit interactions

    International Nuclear Information System (INIS)

    Niţa, Marian; Ostahie, Bogdan; Marinescu, D C; Manolescu, Andrei; Gudmundsson, Vidar

    2012-01-01

    When subjected to a linearly polarized terahertz pulse, a mesoscopic ring endowed with spin-orbit interaction (SOI) of the Rashba-Dresselhaus type exhibits non-uniform azimuthal charge and spin distributions. Both types of SOI couplings are considered linear in the electron momentum. Our results are obtained within a formalism based on the equation of motion satisfied by the density operator which is solved numerically for different values of the angle φ, the angle determining the polarization direction of the laser pulse. Solutions thus obtained are later employed in determining the time-dependent charge and spin currents, whose values are calculated in the stationary limit. Both these currents exhibit an oscillatory behavior complicated in the case of the spin current by a beating pattern. We explain this occurrence on account of the two spin-orbit interactions which force the electron spin to oscillate between the two spin quantization axes corresponding to Rashba and Dresselhaus interactions. The oscillation frequencies are explained using the single particle spectrum.

  4. Fermi Liquid Instabilities in the Spin Channel

    International Nuclear Information System (INIS)

    Wu, Congjun

    2010-01-01

    We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F l a (l > 0)). The ordered phases are classified into two classes, dubbed the α and β-phases by analogy to the superfluid 3 He-A and B-phases. The Fermi surfaces in the α-phases exhibit spontaneous anisotropic distortions, while those in the β-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the α-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the α and β-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel β-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.

  5. Fermi Liquid Instabilities in the Spin Channel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Congjun; /Santa Barbara, KITP; Sun, Kai; Fradkin, Eduardo; /Illinois U., Urbana; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-16

    We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F{sub l}{sup a} (l > 0)). The ordered phases are classified into two classes, dubbed the {alpha} and {beta}-phases by analogy to the superfluid {sup 3}He-A and B-phases. The Fermi surfaces in the {alpha}-phases exhibit spontaneous anisotropic distortions, while those in the {beta}-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the {alpha}-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the {alpha} and {beta}-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel {beta}-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.

  6. Shape distortions in fabric reinforced composite products due to processing induced fibre reorientation

    NARCIS (Netherlands)

    Lamers, E.A.D.

    2004-01-01

    Woven fabric reinforced composite materials are typically applied in plate or shell structures, such as ribs, stiffeners and skins. Products of these types can be produced with several production processes. A few examples are diaphragm forming, matched metal die forming and rubber press forming.

  7. Spinning particle approach to higher spin field theory

    International Nuclear Information System (INIS)

    Corradini, Olindo

    2011-01-01

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

  8. Entanglement entropy in random quantum spin-S chains

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  9. Spin current through quantum-dot spin valves

    International Nuclear Information System (INIS)

    Wang, J; Xing, D Y

    2006-01-01

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

  10. Spin Transfer Torque in Graphene

    Science.gov (United States)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  11. A cluster expansion for interacting spin-flip processes

    Directory of Open Access Journals (Sweden)

    Campanino Massimo

    2017-01-01

    Full Text Available We consider a system of spin flip processes, one-for each point of ℤ${\\mathbb Z}$, interacting through an Ising type interaction. We construct a cluster expansion and prove that it is convergent when the intensity h of the spin-flip processes is sufficiently high. The system is relevant in the study of the ground state of a quantum Ising process with transverse magnetic field.

  12. Spin waves and spin instabilities in quantum plasmas

    OpenAIRE

    Andreev, P. A.; Kuz'menkov, L. S.

    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. Inst...

  13. Spin transport in spin filtering magnetic tunneling junctions.

    Science.gov (United States)

    Li, Yun; Lee, Eok Kyun

    2007-11-01

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

  14. 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 based...... on a combination of the spin-orbit coupling and the mutual long-ranged Coulomb interaction. Compared to existing schemes using the exchange coupling, the spin-orbit induced coupling is less sensitive to random electrical fluctuations in the electrodes defining the quantum dots....

  15. High-field spin dynamics of antiferromagnetic quantum spin chains

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  16. Visualizing spin states using the spin coherent state representation

    Science.gov (United States)

    Lee Loh, Yen; Kim, Monica

    2015-01-01

    Orbital angular momentum eigenfunctions are readily understood in terms of spherical harmonics. However, the quantum mechanical phenomenon of spin is often said to be mysterious and hard to visualize, with no classical analog. Many textbooks give a heuristic and somewhat unsatisfying picture of a precessing spin vector. Here, we show that the spin-coherent-state representation is a striking, elegant, and mathematically meaningful tool for visualizing spin states. We also demonstrate that cartographic projections such as the Hammer projection are useful for visualizing functions defined on spherical surfaces.

  17. QED approach to the nuclear spin-spin coupling tensor

    International Nuclear Information System (INIS)

    Romero, Rodolfo H.; Aucar, Gustavo A.

    2002-01-01

    A quantum electrodynamical approach for the calculation of the nuclear spin-spin coupling tensor of nuclear-magnetic-resonance spectroscopy is given. Quantization of radiation fields within the molecule is considered and expressions for the magnetic field in the neighborhood of a nucleus are calculated. Using a generalization of time-dependent response theory, an effective spin-spin interaction is obtained from the coupling of nuclear magnetic moments to a virtual quantized magnetic field. The energy-dependent operators obtained reduce to usual classical-field expressions at suitable limits

  18. Traditional Birth Attendant reorientation and Motherpacks incentive's effect on health facility delivery uptake in Narok County, Kenya: An impact analysis.

    Science.gov (United States)

    Kitui, John Emmanuel; Dutton, Vaughan; Bester, Dirk; Ndirangu, Rachel; Wangai, Susan; Ngugi, Stephen

    2017-04-21

    A community health programme in Narok County in Kenya aimed to improve skilled birth assistance during childbirth through two demand side interventions. First, traditional birth attendants (TBAs) were co-opted into using their influence to promote use of skilled birth attendants (SBAs) at health facilities during delivery, and to accompany pregnant women to health facilities in return for a Ksh500 (Approximately USD5 as of August 2016) cash incentive for each pregnant mother they accompanied. Secondly, a free Motherpack consisting of a range of baby care items was given to each mother after delivering at a health facility. This paper estimates the impact of these two interventions on trends of facility deliveries over a 36-month period here. Dependency or inferred causality was estimated between reorientation of TBAs and provision of Motherpacks with changes in facility delivery numbers. The outcome variable consists of monthly facility delivery data from 28 health facilities starting from January 2013 to December 2015 obtained from the District Health Information Systems 2 (DHIS2). Data were collected on the 13th, 14th or 15th of each month, resulting in a total of 35 collections, over 35 months. The intervention data consisted of the starting month for each of the two interventions at each of the 28 facilities. A negative binomial generalized linear model framework is applied to model the relationship as all variables were measured as count data and were overdispersed. All analyses were conducted using R software. During the 35 months considered, a total of 9095 health facility deliveries took place, a total of 408 TBAs were reached, and 2181 Motherpacks were distributed. The reorientation of TBAs was significant (p = 0.009), as was the provision of Motherpacks (p = .0001). The number of months that passed since the start of the intervention was also found to be significant (p = 0.033). The introduction of Motherpacks had the greatest effect on the

  19. ac spin-Hall effect

    International Nuclear Information System (INIS)

    Entin-Wohlman, O.

    2005-01-01

    Full Text:The spin-Hall effect is described. The Rashba and Dresselhaus spin-orbit interactions are both shown to yield the low temperature spin-Hall effect for strongly localized electrons coupled to phonons. A frequency-dependent electric field E(ω) generates a spin-polarization current, normal to E, due to interference of hopping paths. At zero temperature the corresponding spin-Hall conductivity is real and is proportional to ω 2 . At non-zero temperatures the coupling to the phonons yields an imaginary term proportional to ω. The interference also yields persistent spin currents at thermal equilibrium, at E = 0. The contributions from the Dresselhaus and Rashba interactions to the interference oppose each other

  20. Observation of the spin Nernst effect

    Science.gov (United States)

    Meyer, S.; Chen, Y.-T.; Wimmer, S.; Althammer, M.; Wimmer, T.; Schlitz, R.; Geprägs, S.; Huebl, H.; Ködderitzsch, D.; Ebert, H.; Bauer, G. E. W.; Gross, R.; Goennenwein, S. T. B.

    2017-10-01

    The observation of the spin Hall effect triggered intense research on pure spin current transport. With the spin Hall effect, the spin Seebeck effect and the spin Peltier effect already observed, our picture of pure spin current transport is almost complete. The only missing piece is the spin Nernst (-Ettingshausen) effect, which so far has been discussed only on theoretical grounds. Here, we report the observation of the spin Nernst effect. By applying a longitudinal temperature gradient, we generate a pure transverse spin current in a Pt thin film. For readout, we exploit the magnetization-orientation-dependent spin transfer to an adjacent yttrium iron garnet layer, converting the spin Nernst current in Pt into a controlled change of the longitudinal and transverse thermopower voltage. Our experiments show that the spin Nernst and the spin Hall effect in Pt are of comparable magnitude, but differ in sign, as corroborated by first-principles calculations.

  1. Symplectic integrators for spin systems

    Science.gov (United States)

    McLachlan, Robert I.; Modin, Klas; Verdier, Olivier

    2014-06-01

    We present a symplectic integrator, based on the implicit midpoint method, for classical spin systems where each spin is a unit vector in R3. Unlike splitting methods, it is defined for all Hamiltonians and is O (3)-equivariant, i.e., coordinate-independent. It is a rare example of a generating function for symplectic maps of a noncanonical phase space. It yields a new integrable discretization of the spinning top.

  2. Asymptotics of relativistic spin networks

    International Nuclear Information System (INIS)

    Barrett, John W; Steele, Christopher M

    2003-01-01

    The stationary phase technique is used to calculate asymptotic formulae for SO(4) relativistic spin networks. For the tetrahedral spin network this gives the square of the Ponzano-Regge asymptotic formula for the SU(2) 6j-symbol. For the 4-simplex (10j-symbol) the asymptotic formula is compared with numerical calculations of the spin network evaluation. Finally, we discuss the asymptotics of the SO(3, 1) 10j-symbol

  3. 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.)

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

    Science.gov (United States)

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

    2018-04-11

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

  5. 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.)

  6. Spin-photon entangling diode

    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 the diode bias and local gating allow for the generation of single photons that are entangled with a robust quantum memory based on the electron spins. Practical performance of this approach to controlled spin-photon entanglement is analyzed....

  7. Spin diffusion in Fermi gases

    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...

  8. Continuum model for chiral induced spin selectivity in helical molecules

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Ernesto [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); González-Arraga, Luis A. [IMDEA Nanoscience, Cantoblanco, 28049 Madrid (Spain); Finkelstein-Shapiro, Daniel; Mujica, Vladimiro [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Berche, Bertrand [Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of); Groupe de Physique Statistique, Institut Jean Lamour, Université de Lorraine, 54506 Vandoeuvre-les-Nancy Cedex (France)

    2015-05-21

    A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented p{sub z} type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the spin-orbit coupling (SOC) opens up an effective π{sub z} − π{sub z} coupling via interbase p{sub x,y} − p{sub z} hopping, introducing spin coupled transport. The resulting continuum model spectrum shows two Kramers doublet transport channels with a gap proportional to the SOC. Each doubly degenerate channel satisfies time reversal symmetry; nevertheless, a bias chooses a transport direction and thus selects for spin orientation. The model predicts (i) which spin orientation is selected depending on chirality and bias, (ii) changes in spin preference as a function of input Fermi level and (iii) back-scattering suppression protected by the SO gap. We compute the spin current with a definite helicity and find it to be proportional to the torsion of the chiral structure and the non-adiabatic Aharonov-Anandan phase. To describe room temperature transport, we assume that the total transmission is the result of a product of coherent steps.

  9. Dependence of the Efficiency of Spin Hall Torque on the Transparency of Pt-Ferromagnetic Layer Interfaces

    OpenAIRE

    Pai, Chi-Feng; Ou, Yongxi; Ralph, D. C.; Buhrman, R. A.

    2014-01-01

    We report that spin current transport across Pt-ferromagnet (FM) interfaces is strongly dependent on the type and the thickness of the FM layer and on post-deposition processing protocols. By employing both harmonic voltage measurements and spin-torque ferromagnetic resonance measurements, we find that the efficiency of the Pt spin Hall effect in exerting a damping-like spin torque on the FM ranges from 0.10 under different interfacial conditions. We also show that the temperature...

  10. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength

    OpenAIRE

    Savochkin, I. V.; J?ckl, M.; Belotelov, V. I.; Akimov, I. A.; Kozhaev, M. A.; Sylgacheva, D. A.; Chernov, A. I.; Shaposhnikov, A. N.; Prokopov, A. R.; Berzhansky, V. N.; Yakovlev, D. R.; Zvezdin, A. K.; Bayer, M.

    2017-01-01

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with ...

  11. Electron spin resonance

    International Nuclear Information System (INIS)

    Wasson, J.R.; Salinas, J.E.

    1980-01-01

    Published literature concerning electron spin resonance (ESR) from July 1977 to July 1979 is reviewed. The 108 literature sources cited were chosen from literally thousands and are intended to serve as a guide to the current literature and to provide an eclectic selection of publications cited for their contributions to the advance and/or applications of ESR spectroscopy. 40 of the sources are reviews, and a table is included to indicate the topic(s) mainly covered in each review. Other divisions of the material reviewed are apparatus and spectral analysis, analytical applications, and selected paramagnetic materials

  12. New possibilities in diagnosis of diseases of the vertebral column and reorientation of diagnostic approach via CT of spine

    International Nuclear Information System (INIS)

    Fenzl, G.; Rath, M.; Steinhoff, H.; Matzen, K.A.

    1984-01-01

    During the last three years (from May 1981 to March 1984) we performed 1368 CT examinations of the spine, 447 of the cervical, 264 of the thoracic and 657 of the lumbar vertebral column. 30% of the CT examinations of the lumbar spine revealed a prolapse of an intervertebral disk. In 38% of the cases involving the thoracic spine metastases were seen. We diagnosed fractures in 10% of the cervical spine and 11% of the thoracic spine examinations. Posttraumatic or postoperative intravertebral haemorrhage was hardly ever diagnosed in our patients (1.9% of the cases). Spinal trauma: The anterior-posterior and lateral plain films continue to be the mainstay of radiographic screening in spinal injury. Nevertheless, the degree of injury is underestimated in a significant number of patients with spinal trauma if conventional radiography is the only diagnostic approach. For further clarification CT proved to be the fastest and best method to recognise the causes and extent of compression of the vertebral canal. CT has attained a high degree of accuracy in the diagnosis of prolapse of intervertebral disks, replacing myelography if the findings are unequivocally established. CT should also be preferred to myelography in suspected recurrent prolapse. Localisation, shape and density are criteria for differentiating between scarification and prolapse via CT. The results show that CT has opened up new possibilities in the diagnosis of spinal diseases and has resulted in a reorientation of the diagnostic approach. (orig.) [de

  13. Angular dependence of spin-orbit spin-transfer torques

    KAUST Repository

    Lee, Ki-Seung

    2015-04-06

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

  14. 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-s...

  15. Acoustically induced spin transport in (110)GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Couto, Odilon D.D. Jr.

    2008-09-29

    In this work, we employ surface acoustic waves (SAWs) to transport and manipulate optically generated spin ensembles in (110) GaAs quantum wells (QWs). The strong carrier confinement into the SAW piezoelectric potential allows for the transport of spin-polarized carrier packets along well-defined channels with the propagation velocity of the acoustic wave. In this way, spin transport over distances exceeding 60 m is achieved, corresponding to spin lifetimes longer than 20 ns. The demonstration of such extremely long spin lifetimes is enabled by three main factors: (i) Suppression of the D'yakonov-Perel' spin relaxation mechanism for z-oriented spins in (110) IIIV QWs; (ii) Suppression of the Bir-Aronov-Pikus spin relaxation mechanism caused by the type-II SAW piezoelectric potential; (iii) Suppression of spin relaxation induced by the mesoscopic carrier confinement into narrow stripes along the SAW wave front direction. A spin transport anisotropy under external magnetic fields (B{sub ext}) is demonstrated for the first time. Employing the well-defined average carrier momentum impinged by the SAW, we analyze the spin dephasing dynamics during transport along the [001] and [1 anti 10] in-plane directions. For transport along [001], fluctuations of the internal magnetic field (B{sub int}), which arises from the spin-orbit interaction associated with the bulk inversion asymmetry of the crystal, lead to decoherence within 2 ns as the spins precess around B{sub ext}. In contrast, for transport along the [1 anti 10] direction, the z-component of the spin polarization is maintained for times one order of magnitude longer due to the non-zero average value of B{sub int}. The dephasing anisotropy between the two directions is fully understood in terms of the dependence of the spin-orbit coupling on carrier momentum direction, as predicted by the D'yakonov-Perel' mechanism for the (110) system. (orig.)

  16. Quasi-two-dimensional spin correlations in the triangular lattice bilayer spin glass LuCoGaO4

    Science.gov (United States)

    Fritsch, K.; Ross, K. A.; Granroth, G. E.; Ehlers, G.; Noad, H. M. L.; Dabkowska, H. A.; Gaulin, B. D.

    2017-09-01

    We present a single-crystal time-of-flight neutron scattering study of the static and dynamic spin correlations in LuCoGaO4, a quasi-two-dimensional dilute triangular lattice antiferromagnetic spin-glass material. This system is based on Co2 + ions that are randomly distributed on triangular bilayers within the YbFe2O4 -type, hexagonal crystal structure. Antiferromagnetic short-range two-dimensional correlations at wave vectors Q =(" close=")1 /3 ,1 /3 ,L )">1 /3 ,1 /3 ,L develop within the bilayers at temperatures as high as | ΘCW|˜100 K and extend over roughly five unit cells at temperatures below Tg=19 K. These two-dimensional static correlations are observed as diffuse rods of neutron scattering intensity along c* and display a continuous spin freezing process in their energy dependence. Aside from exhibiting these typical spin-glass characteristics, this insulating material reveals a novel gapped magnetic resonant spin excitation at Δ E ˜12 meV localized around Q. The temperature dependence of the spin gap associated with this two-dimensional excitation correlates with the evolution of the static correlations into the spin-glass state ground state. We associate it with the effect of the staggered exchange field acting on the Seff=1 /2 Ising-like doublet of the Co2 + moments.

  17. Dynamic arrest in a liquid of symmetric dumbbells: reorientational hopping for small molecular elongations.

    Science.gov (United States)

    Moreno, Angel J; Chong, Song-Ho; Kob, Walter; Sciortino, Francesco

    2005-11-22

    We present extensive equilibrium and out-of-equilibrium molecular-dynamics simulations of a liquid of symmetric dumbbell molecules, for constant packing fraction, as a function of temperature and molecular elongation. We compute diffusion constants as well as odd and even orientational correlators. The notations odd and even refer to the parity of the order l of the corresponding Legendre l polynomial, evaluated for the orientation of the molecular axis relative to its initial position. Rotational degrees of freedom of order l are arrested if, in the long-time limit, the corresponding orientational l correlator does not decay to zero. It is found that for large elongations translational and rotational degrees of freedom freeze at the same temperature. For small elongations only the even rotational degrees of freedom remain coupled to translational motions and arrest at a finite common temperature. On the contrary, the odd rotational degrees of freedom remain ergodic at all investigated temperatures. Hence, in the translationally arrested state, each molecule remains trapped in the cage formed by its neighboring molecules, but is able to perform 180 degrees rotations, which lead to relaxation only for the odd orientational correlators. The temperature dependence of the characteristic time of these residual rotations is well described by an Arrhenius law. Finally, we discuss the evidence in favor of the presence of the type-A transition for the odd rotational degrees of freedom, as predicted by mode-coupling theory for small molecular elongations. This transition is distinct from the type-B transition, associated with the arrest of the translational and even rotational degrees of freedom for small elongations, and with all degrees of freedom for large elongations. Odd orientational correlators are computed for small elongations at very low temperatures in the translationally arrested state. The obtained results suggest that hopping events restore the ergodicity of

  18. Spin caloritronics, origin and outlook

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Haiming, E-mail: haiming.yu@buaa.edu.cn [Fert Beijing Institute, School of Electronic and Information Engineering, BDBC, Beihang University (China); Brechet, Sylvain D. [Institute of Physics, station 3, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne-EPFL (Switzerland); Ansermet, Jean-Philippe, E-mail: jean-philippe.ansermet@epfl.ch [Institute of Physics, station 3, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne-EPFL (Switzerland)

    2017-03-03

    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. - Highlights: • Thermodynamic description of transport: three-current model. • Magneto-thermoelectric power and spin-dependent Peltier effects. • Thermal

  19. Nuclear Spin-Spin Coupling in HD, HT, and DT

    Science.gov (United States)

    Puchalski, Mariusz; Komasa, Jacek; Pachucki, Krzysztof

    2018-02-01

    The interaction between nuclear spins in a molecule is exceptionally sensitive to the physics beyond the standard model. However, all present calculations of the nuclear spin-spin coupling constant J are burdened by computational difficulties, which hinders the comparison to experimental results. Here, we present a variational approach and calculate the constant J in the hydrogen molecule with the controlled numerical precision, using the adiabatic approximation. The apparent discrepancy with experimental result is removed by an analysis of nonadiabatic effects based on the experimental values of the J constant for HD, HT, and DT molecules. This study significantly improves the reliability of the NMR theory for searching new physics in the spin-spin coupling.

  20. On spin dependence of relativistic acoustic geometry

    International Nuclear Information System (INIS)

    Pu, Hung-Yi; Chang, Hsiang-Kuang; Maity, Ishita; Das, Tapas Kumar

    2012-01-01

    This work makes the first ever attempt to understand the influence of the black hole background spacetime in determining the fundamental properties of the embedded relativistic acoustic geometry. To accomplish such task, we investigate the role of the spin angular momentum of the astrophysical black hole (the Kerr parameter a—a representative feature of the background black hole metric) in estimating the value of the acoustic surface gravity (the representative feature of the corresponding analogue spacetime). Since almost all astrophysical black holes are supposed to posses some degree of intrinsic rotation, the influence of the Kerr parameter on classical analogue models is very important to understand. We study the general relativistic, axially symmetric, non-self-gravitating inflow of the hydrodynamic fluid onto a rotating astrophysical black hole from the dynamical systems point of view. In this work the location of the acoustic horizon inside such fluid flow is identified and the associated acoustic surface gravity is estimated. We study the dependence of such surface gravity as a function of the Kerr parameter as well as with other dynamical and thermodynamic variables governing the fluid flow under strong gravity, and demonstrate that for retrograde flow, the surface gravity (and hence the associated analogue Hawking temperature) correlates with the black hole spin in general, whereas for the prograde flow, the surface gravity as well as the analogue temperature correlates with the black hole spin for slow to moderately rotating holes, but anti-correlates with the spin for fast to extremely rotating holes. We found that for certain values of the initial boundary conditions, more than one acoustic horizons, namely two black hole types and one white hole type, may form, and the surface gravity may become formally infinite at the acoustic white hole. We discuss the possible connection between the corresponding analogue Hawking temperature and astrophysically

  1. Snakes and spin rotators

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1990-01-01

    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 -4 will be significant. 2 refs., 5 figs

  2. Role of coherence in transport through engineered atomic spin devices

    Science.gov (United States)

    Shakirov, Alexey M.; Shchadilova, Yulia E.; Rubtsov, Alexey N.; Ribeiro, Pedro

    2016-12-01

    We give a further step in the quantum mechanical description of engineered atomic spin structures by deriving a master equation of the Redfield type that governs the dynamics of the atomic spin density matrix. By generalizing this approach to charge-specific density matrices, we are able to describe magnetic transport quantities, such as the average inelastic current and the shot noise, accessible by tunneling spectroscopy. Our method suitably describes moderate lead-atom coupling regimes where quantum coherence effects cannot be disregarded. We contrast our approach with the existing descriptions in terms of rate equations and show examples where coherence effects are crucial to understand the physics of spin-polarized tunnel current through spin structures.

  3. The transverse spin

    Energy Technology Data Exchange (ETDEWEB)

    Artru, X. [Institut de Physique Nucleaire de Lyon, IN2P3-CNRS, Universite Claude Bernard, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France)

    2002-07-01

    The aim of this introduction, which is far from exhaustive, was to give an overview on the richness of transverse spin quantity and its differences in comparison with helicity. From the experimental point of view, the physics of quark transversity in deep inelastic reaction is still practically unexplored. This situation will certainly change rapidly, with planned experiments at DESY (HERMES), Brookhaven (RHIC) and CERN (COMPAS), but there is a long way before knowing the transversity distribution, {delta}q(x), as precisely as the helicity distribution, {delta}q(x), now. Unless polarized anti-proton beams become feasible, experiments probing quark transversity will rely mainly on 'quark polarimeters', like {lambda}'s or the Collins effect. These polarimeters will have to be calibrated at e{sup +}e{sup -} colliders. The Collins polarimeter will by the way allow the flavor decomposition of {delta}q(x), using mesons of various charging and strangeness. Quark polarimetry is by itself an interesting topic of non-perturbative QCD, and may teach us something about the breaking of chiral symmetry. Let us recall that, if chiral symmetry were unbroken, transversity would be undefined. The transversity physics program is not at all a 'remake' of the helicity one. Helicity and transversity probe rather different aspects of the hadron structure. Differences between {delta}q(x) and {delta}q(x) will reveal non-relativistic effects in the baryon wave function. Also {delta}q(x) does not couples to gluon distributions, thus it is free from anomaly. In that respect it is a more clean probe than {delta}q(x). In fact, the combination of helicity and transversity measurements will perhaps be the most interesting. Polarized parton densities taking only the helicity degree of freedom are almost 'classical'. Quantum aspects of spin correlations, like violation of Bell's inequality, can be found only when varying the spin quantification axis

  4. Training Level Does Not Affect Auditory Perception of The Magnitude of Ball Spin in Table Tennis.

    Science.gov (United States)

    Santos, Daniel P R; Barbosa, Roberto N; Vieira, Luiz H P; Santiago, Paulo R P; Zagatto, Alessandro M; Gomes, Matheus M

    2017-01-01

    Identifying the trajectory and spin of the ball with speed and accuracy is critical for good performance in table tennis. The aim of this study was to analyze the ability of table tennis players presenting different levels of training/experience to identify the magnitude of the ball spin from the sound produced when the racket hit the ball. Four types of "forehand" contact sounds were collected in the laboratory, defined as: Fast Spin (spinning ball forward at 140 r/s); Medium Spin (105 r/s); Slow Spin (84 r/s); and Flat Hit (less than 60 r/s). Thirty-four table tennis players of both sexes (24 men and 10 women) aged 18-40 years listened to the sounds and tried to identify the magnitude of the ball spin. The results revealed that in 50.9% of the cases the table tennis players were able to identify the ball spin and the observed number of correct answers (10.2) was significantly higher (χ 2 = 270.4, p ball spin. This indicates that auditory information contributes to identification of the magnitude of the ball spin, however, it also reveals that, in table tennis, the level of training does not interfere with the auditory perception of the ball spin.

  5. Spin transfer matrix formulation and snake resonances for polarized proton beams

    International Nuclear Information System (INIS)

    Tepikian, S.

    1986-01-01

    The polarization of a spin polarized proton beam in a circular accelerator is described by a spin transfer matrix. Using this method, they investigate three problems: (1) the crossing of multiple spin resonances, (2) resonance jumping and (3) an accelerator with Siberian snakes. When crossing two (or more) spin resonances, there are no analytic solutions available. However, they can obtain analytic expressions if the two spin resonances are well separated (nonoverlapping) or very close together (overlapping). Between these two extremes they resort to numerical solution of the spin equations. Resonance jumping can be studied using the tools developed for analyzing the cross of multiple spin resonances. These theoretical results compare favorably with experimental results obtained from the AGS at Brookhaven. For large accelerators, resonance jumping becomes impractical and other methods such as Siberian snakes must be used to keep the beam spin polarized. An accelerator with Siberian snakes and isolated spin resonances can be described with a spin transfer matrix. From this, they find a new type of spin depolarizing resonance, called snake resonances

  6. Hippocampal-dependent familiar area map supports corrective re-orientation following navigational error during pigeon homing: a GPS-tracking study.

    Science.gov (United States)

    Gagliardo, Anna; Ioalè, Paolo; Savini, Maria; Dell'Omo, Giacomo; Bingman, Verner P

    2009-06-01

    It is hypothesized that a central role of the vertebrate hippocampal formation (HF) in behavior is the learning and operation of a map-like representation of familiar landmarks and landscape features. One critical property of a map is that it should enable an individual to re-orient towards a goal location following a navigational error. To test this prediction on a spatial scale consistent with their naturally occurring behavior, control and HF-lesioned homing pigeons were trained from two locations and then subsequently released, while carrying portable GPS-tracking devices, following a phase-shift treatment. Analyses revealed that the HF-lesioned pigeons were less successful than control pigeons in re-orienting homewards following the phase-shift-induced error in their initial orientation. Furthermore, the observation that HF-lesioned pigeons were found to routinely ignore a land-sea landscape boundary when returning home from one of the release sites suggests that coarse landscape features may be an underappreciated source of navigational information for homing pigeons. The data demonstrate that, on a scale of tens of kilometers, homing pigeons are able to learn a hippocampal-dependent, map-like representation of familiar landmarks/landscape features that can support corrective re-orientation following a navigational error.

  7. Tunneling conductance of a two-dimensional electron gas with Dresselhaus spin-orbit coupling

    International Nuclear Information System (INIS)

    Srisongmuang, B.; Ka-oey, A.

    2012-01-01

    We theoretically studied the spin-dependent charge transport in a two-dimensional electron gas with Dresselhaus spin-orbit coupling (DSOC) and metal junctions. It is shown that the DSOC energy can be directly measured from the tunneling conductance spectrum. We found that spin polarization of the conductance in the propagation direction can be obtained by injecting from the DSOC system. We also considered the effect of the interfacial scattering barrier (both spin-flip and non-spin-flip scattering) on the overall conductance and the spin polarization of the conductance. It is found that the increase of spin-flip scattering can enhance the conductance under certain conditions. Moreover, both types of scattering can increase the spin polarization below the branches crossing of the energy band. - Highlights: → DSOC energy can be directly measured from tunneling conductance spectrum. → Spin polarization of conductance in the propagation direction can be obtained by injecting from DSOC system. → Both types of scattering can increase spin polarization.

  8. Superconductive analogue of spin glasses

    International Nuclear Information System (INIS)

    Feigel'man, M.; Ioffe, L.; Vinokur, V.; Larkin, A.

    1987-07-01

    The properties of granular superconductors in magnetic fields, namely the existence of a new superconductive state analogue of the low-temperature superconductive state in spin glasses are discussed in the frame of the infinite-range model and the finite-range models. Experiments for elucidation of spin-glass superconductive state in real systems are suggested. 30 refs

  9. Spinning top—the question

    Science.gov (United States)

    Featonby, David

    2017-11-01

    The motion of a spinning top can be mystifying at times until some basic principles are understood. In this question the key to understanding what happens is the nature of the bottom tip of the top in contact with the surface on which it spins.

  10. Decoherence in Quantum Spin Systems

    NARCIS (Netherlands)

    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

  11. Nuclear Spins in Quantum Dots

    NARCIS (Netherlands)

    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,

  12. Black Hole Spin Measurement Uncertainty

    Science.gov (United States)

    Salvesen, Greg; Begelman, Mitchell C.

    2018-01-01

    Angular momentum, or spin, is one of only two fundamental properties of astrophysical black holes, and measuring its value has numerous applications. For instance, obtaining reliable spin measurements could constrain the growth history of supermassive black holes and reveal whether relativistic jets are powered by tapping into the black hole spin reservoir. The two well-established techniques for measuring black hole spin can both be applied to X-ray binaries, but are in disagreement for cases of non-maximal spin. This discrepancy must be resolved if either technique is to be deemed robust. We show that the technique based on disc continuum fitting is sensitive to uncertainties regarding the disc atmosphere, which are observationally unconstrained. By incorporating reasonable uncertainties into black hole spin probability density functions, we demonstrate that the spin measured by disc continuum fitting can become highly uncertain. Future work toward understanding how the observed disc continuum is altered by atmospheric physics, particularly magnetic fields, will further strengthen black hole spin measurement techniques.

  13. SPIN PHYSICS: Lasers at work

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Lasers are now an everyday tool in particle physics, particularly for the spin polarization of beams, targets, and even short-lived particles. Development has been boosted in recent years by the availability of reliable multiwatt tunable lasers to select spin in an experimentally useful sample

  14. Josephson spin current in triplet superconductor junctions

    OpenAIRE

    Asano, Yasuhiro

    2006-01-01

    This paper theoretically discusses the spin current in spin-triplet superconductor / insulator / spin-triplet superconductor junctions. At low temperatures, a midgap Andreev resonant state anomalously enhances not only the charge current but also the spin current. The coupling between the Cooper pairs and the electromagnetic fields leads to the Frounhofer pattern in the direct current spin flow in magnetic fields and the alternative spin current under applied bias-voltages.

  15. Large spin-valve effect in a lateral spin-valve device based on ferromagnetic semiconductor GaMnAs

    Science.gov (United States)

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

    2018-03-01

    We investigate the spin-dependent transport properties of a lateral spin-valve device based on the ferromagnetic semiconductor GaMnAs. This device is composed of a GaMnAs channel layer grown on GaAs with a narrow trench across the channel. Its current-voltage characteristics show tunneling behavior. Large magnetoresistance (MR) ratios of more than ˜10% are obtained. These values are much larger than those (˜0.1%) reported for lateral-type spin metal-oxide-semiconductor field-effect transistors. The magnetic field direction dependence of the MR curve differs from that of the anisotropic magnetoresistance of GaMnAs, which confirms that the MR signal originates from the spin-valve effect between the GaMnAs electrodes.

  16. High efficiency spin-valve and spin-filter in a doped rhombic graphene quantum dot device

    Science.gov (United States)

    Silva, P. V.; Saraiva-Souza, A.; Maia, D. W.; Souza, F. M.; Filho, A. G. Souza; Meunier, V.; Girão, E. C.

    2018-04-01

    Spin-polarized transport through a rhombic graphene quantum dot (rGQD) attached to armchair graphene nanoribbon (AGNR) electrodes is investigated by means of the Green's function technique combined with single-band tight-binding (TB) approach including a Hubbard-like term. The Hubbard repulsion was included within the mean-field approximation. Compared to anti-ferromagnetic (AFM), we show that the ferromagnetic (FM) ordering of the rGQD corresponds to a smaller bandgap, thus resulting in an efficient spin injector. As a consequence, the electron transport spectrum reveals a spin valve effect, which is controlled by doping with B/N atoms creating a p-n-type junction. The calculations point out that such systems can be used as spin-filter devices with efficiency close to a 100 % .

  17. Disorder and Quantum Spin Ice

    Science.gov (United States)

    Martin, N.; Bonville, P.; Lhotel, E.; Guitteny, S.; Wildes, A.; Decorse, C.; Ciomaga Hatnean, M.; Balakrishnan, G.; Mirebeau, I.; Petit, S.

    2017-10-01

    We report on diffuse neutron scattering experiments providing evidence for the presence of random strains in the quantum spin-ice candidate Pr2Zr2O7 . Since Pr3 + is a non-Kramers ion, the strain deeply modifies the picture of Ising magnetic moments governing the low-temperature properties of this material. It is shown that the derived strain distribution accounts for the temperature dependence of the specific heat and of the spin-excitation spectra. Taking advantage of mean-field and spin-dynamics simulations, we argue that the randomness in Pr2Zr2O7 promotes a new state of matter, which is disordered yet characterized by short-range antiferroquadrupolar correlations, and from which emerge spin-ice-like excitations. Thus, this study gives an original research route in the field of quantum spin ice.

  18. Disorder and Quantum Spin Ice

    Directory of Open Access Journals (Sweden)

    N. Martin

    2017-10-01

    Full Text Available We report on diffuse neutron scattering experiments providing evidence for the presence of random strains in the quantum spin-ice candidate Pr_{2}Zr_{2}O_{7}. Since Pr^{3+} is a non-Kramers ion, the strain deeply modifies the picture of Ising magnetic moments governing the low-temperature properties of this material. It is shown that the derived strain distribution accounts for the temperature dependence of the specific heat and of the spin-excitation spectra. Taking advantage of mean-field and spin-dynamics simulations, we argue that the randomness in Pr_{2}Zr_{2}O_{7} promotes a new state of matter, which is disordered yet characterized by short-range antiferroquadrupolar correlations, and from which emerge spin-ice-like excitations. Thus, this study gives an original research route in the field of quantum spin ice.

  19. Dependence of the Spin Transfer Torque Switching Current Density on the Exchange Stiffness Constant

    OpenAIRE

    You, Chun-Yeol

    2012-01-01

    We investigate the dependence of the switching current density on the exchange stiffness constant in the spin transfer torque magnetic tunneling junction structure with micromagnetic simulations. Since the widely accepted analytic expression of the switching current density is based on the macro-spin model, there is no dependence of the exchange stiffness constant. When the switching is occurred, however, the spin configuration forms C-, S-type, or complicated domain structures. Since the spi...

  20. Theory for spin and orbital orderings in high temperature phase in $YVO_3$

    OpenAIRE

    De Silva, Theja N.; Joshi, Anuvrat; Ma, Michael; Zhang, Fu Chun

    2003-01-01

    Motivated by the recent neutron diffraction experiment on $YVO_3$, we consider a microscopic model where each $V^{3+}$ ion is occupied by two 3d electrons of parallel spins with two fold degenerate orbital configurations. The mean field classical solutions of the spin-orbital superexchange model predicts an antiferro-orbital ordering at a higher temperature followed by a C-type antiferromagnetic spin ordering at a lower temperature. Our results are qualitatively consistent with the observed o...