WorldWideScience

Sample records for monopolar spin orientation

  1. 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.

  2. Determining the Stellar Spin Axis Orientation

    Science.gov (United States)

    Lesage, Anna-Lea; Wiedemann, Gunter

    2015-01-01

    We present an observing method that permits the determination of the absolute stellar spin axis position angle based on spectro-astrometric observations for slowly-rotating late-type stars. This method is complementary to current interferometric observations that determine the orientation of stellar spin axis for early-type fast-rotating stars. Spectro-astrometry enables us to study phenomena below the diffraction limit, at the milli-arcsecond scale. It relies on the wavelength dependent variations of the centroid position of a structured source in a long-slit spectrum. A rotating star has a slight tilt in its spectral lines, which induces a displacement of the photocentre's position. By monitoring the amplitude of the displacement for varying slit orientations, we can infer the absolute position angle of the stellar spin axis. Finally, we present first observational results on Aldebaran obtained with the Thüringer Landesternwarte high resolution spectrograph. We were able to retrieve Aldebaran's position angle with less than 10° errors.

  3. Binary black hole mergers: large kicks for generic spin orientations

    CERN Document Server

    Tichy, W; Tichy, Wolfgang; Marronetti, Pedro

    2007-01-01

    We present results from several simulations of equal mass black holes with spin. The spin magnitudes are $S/m^2=0.8$ in all cases, but we vary the spin orientations arbitrarily, in and outside the orbital plane. We find that in all but one case the final merged black hole acquires a kick of more than 1000 km/s, indicating that kicks of this magnitude are likely to be generic and should be expected for mergers with general spin orientations. The maximum kick velocity we find is 2500 km/s and occurs for initial spins which are anti-aligned in the initial orbital plane.

  4. Optical Orientation and Inverse Spin Hall Effect as Effective Tools to Investigate Spin-Dependent Diffusion

    Directory of Open Access Journals (Sweden)

    Marco Finazzi

    2016-11-01

    Full Text Available In this work we address optical orientation, a process consisting in the excitation of spin polarized electrons across the gap of a semiconductor. We show that the combination of optical orientation with spin-dependent scattering leading to the inverse spin-Hall effect, i.e., to the conversion of a spin current into an electrical signal, represents a powerful tool to generate and detect spin currents in solids. We consider a few examples where these two phenomena together allow addressing the spin-dependent transport properties across homogeneous samples or metal/semiconductor Schottky junctions.

  5. Orientation selective DEER measurements on vinculin tail at X-band frequencies reveal spin label orientations

    Science.gov (United States)

    Abé, Christoph; Klose, Daniel; Dietrich, Franziska; Ziegler, Wolfgang H.; Polyhach, Yevhen; Jeschke, Gunnar; Steinhoff, Heinz-Jürgen

    2012-03-01

    Double electron electron resonance (DEER) spectroscopy has been established as a valuable method to determine distances between spin labels bound to protein molecules. Caused by selective excitation of molecular orientations DEER primary data also depend on the mutual orientation of the spin labels. For a doubly spin labeled variant of the cytoskeletal protein vinculin tail strong orientation selection can be observed already at X-band frequencies, which allows us to reduce the problem to the relative orientation of two molecular axes and the spin-spin axis parameterized by three angles. A full grid search of parameter space reveals that the DEER experiment introduces parameter-space symmetry higher than the symmetry of the spin Hamiltonian. Thus, the number of equivalent parameter sets is twice as large as expected and the relative orientation of the two spin labels is ambiguous. Except for this inherent ambiguity the most probable relative orientation of the two spin labels can be determined with good confidence and moderate uncertainty by global fitting of a set of five DEER experiments at different offsets between pump and observer frequency. The experiment provides restraints on the angles between the z axis of the nitroxide molecular frame and the spin-spin vector and on the dihedral between the two z axes. When using the same type of label at both sites, assignment of the angle restraints is ambiguous and the sign of the dihedral restraint is also ambiguous.

  6. Optically oriented electron spin transmission across ferromagnet/semiconductor interfaces

    Science.gov (United States)

    Taniyama, T.; Suzuki, I.; Wada, E.; Shirahata, Y.; Naito, T.; Itoh, M.; Yamaguchi, M.

    2011-10-01

    Electron spin transmission across ferromagnetic metal/semiconductor interfaces with different ferromagnetic contacts, i.e., Fe and FeGa, is studied using optical spin orientation method. The bias dependence of spin dependent photocurrent, which is the difference between the photocurrents excited with left- and right- handed circularly polarized lights, is found to show a dip-like feature at -0.058 and 0.021 V for Fe and FeGa contacts, respectively. The origin of the bias dependence of the spin dependent photocurrent is discussed on the basis of the Breit-Wigner type resonant tunneling process via interface resonant states, comparing the results for the both contacts. The results also indicate that the control of interface states is crucial to achieve efficient spin filtering effect at the ferromagnet/semiconductor interfaces.

  7. A new spin-oriented nuclei facility: POLAREX

    Directory of Open Access Journals (Sweden)

    Etilé A.

    2014-03-01

    Full Text Available Using the On-Line Nuclear Orientation method, POLAREX (POLARization of EXotic nuclei is a new facility allowing to study the anisotropic decay of spin-oriented nuclei. Based on the combination of on-line implantation of radioactive nuclei with Low Temperature Nuclear Orientation technique and Nuclear Magnetic Resonance, POLAREX allows to measure nuclear electromagnetic moments and ground-state spins, in the aim to get information about the wave function composition of the nuclear state. Polarized nuclei can also be used to study fundamental interactions involving nuclear β-decay asymmetries. The POLAREX infrastructure will be installed at Accélérateur Linéaire auprés du Tandem d’Orsay in order to study neutron-rich nuclei, some of which have not been studied yet. Will be presented here, all the possibilities of this new facility and a non exhaustive scientific program.

  8. Spin Flips - II. Evolution of dark matter halo spin orientation, and its correlation with major mergers

    CERN Document Server

    Bett, Philip E

    2015-01-01

    We expand our previous study on the relationship between changes in the orientation of the angular momentum vector of dark matter haloes ("spin flips") and changes in their mass (Bett & Frenk 2012), to cover the full range of halo masses in a simulation cube of length 100 $h^{-1}$ Mpc. Since strong disturbances to a halo (such as might be indicated by a large change in the spin direction) are likely also to disturb the galaxy evolving within, spin flips could be a mechanism for galaxy morphological transformation without involving major mergers. We find that 35% of haloes have, at some point in their lifetimes, had a spin flip of at least $45\\deg$ that does not coincide with a major merger. Over 75% of large spin flips coincide with non-major mergers; only a quarter coincide with major mergers. We find a similar picture for changes to the inner-halo spin orientation, although here there is an increased likelihood of a flip occurring. Changes in halo angular momentum orientation, and other such measures of...

  9. Spin orientation in solid solution hematite-ilmenite

    DEFF Research Database (Denmark)

    Brok, Erik; Frandsen, Cathrine; Lefmann, Kim

    2017-01-01

    The spin orientation in synthetic hematite-ilmenite samples and in a sample of natural hematite was studied from room temperature to above the antiferromagnetic-paramagnetic phase transition (the Néel temperature; TN ≈ 600–950 K) by neutron powder diffraction and at room temperature by Mössbauer ...... in understanding of one of the two main mineral systems responsible for rock magnetism....

  10. Spatial Orientation of Spin Vectors of Blue-shifted Galaxies

    CERN Document Server

    Yadav, S N; Saurer, W

    2016-01-01

    We present the analysis of the spin vector orientation of 5$\\,$987 SDSS galaxies having negative redshift from $-$87.6 to $-$0.3 km$\\,$s$^{-1}$. Two dimensional observed parameters are used to compute three dimensional galaxy rotation axes by applying `position angle--inclination' method. We aim to examine the non-random effects in the spatial orientation of blue-shifted galaxies. We generate 5$\\times$10$^6$ virtual galaxies to find expected isotropic distributions by performing numerical simulations. We have written MATLAB program to facilitate the simulation process and eliminate the manual errors in the process. Chi-square, auto-correlation, and the Fourier tests are used to examine non-random effects in the polar and azimuthal angle distributions of the galaxy rotation axes. In general, blue-shifted galaxies show no preferred alignments of galaxy rotation axes. Our results support Hierarchy model, which suggests a random orientation of angular momentum vectors of galaxies. However, local effects are noted...

  11. The Feynman propagator for quantum gravity: spin foams, proper time, orientation, causality and timeless-ordering

    CERN Document Server

    Oriti, D

    2004-01-01

    We discuss the notion of causality in Quantum Gravity in the context of sum-over-histories approaches, in the absence therefore of any background time parameter. In the spin foam formulation of Quantum Gravity, we identify the appropriate causal structure in the orientation of the spin foam 2-complex and the data that characterize it; we construct a generalised version of spin foam models introducing an extra variable with the interpretation of proper time and show that different ranges of integration for this proper time give two separate classes of spin foam models: one corresponds to the spin foam models currently studied, that are independent of the underlying orientation/causal structure and are therefore interpreted as a-causal transition amplitudes; the second corresponds to a general definition of causal or orientation dependent spin foam models, interpreted as causal transition amplitudes or as the Quantum Gravity analogue of the Feynman propagator of field theory, implying a notion of ''timeless ord...

  12. Ferrimagnetic spin-1/2 chain of alternating Ising and Heisenberg spins in arbitrarily oriented magnetic field

    Directory of Open Access Journals (Sweden)

    J. Strečka

    2012-12-01

    Full Text Available The ferrimagnetic spin-1/2 chain composed of alternating Ising and Heisenberg spins in an arbitrarily oriented magnetic field is exactly solved using the spin-rotation transformation and the transfer-matrix method. It is shown that the low-temperature magnetization process depends basically on a spatial orientation of the magnetic field. A sharp stepwise magnetization curve with a marked intermediate plateau, which emerges for the magnetic field applied along the easy-axis direction of the Ising spins, becomes smoother and the intermediate plateau shrinks if the external field is tilted from the easy-axis direction. The magnetization curve of a polycrystalline system is also calculated by performing powder averaging of the derived magnetization formula. The proposed spin-chain model brings an insight into high-field magnetization data of 3d-4f bimetallic polymeric compound Dy(NO3(DMSO2Cu(opba(DMSO2, which provides an interesting experimental realization of the ferrimagnetic chain composed of two different but regularly alternating spin-1/2 magnetic ions Dy3+ and Cu2+ that are reasonably approximated by the notion of Ising and Heisenberg spins, respectively.

  13. Zero-mass limit of a Dirac spinor with general spin orientation

    CERN Document Server

    Sahin, I

    2016-01-01

    The helicity eigenstates which describe the fermions with a special spin orientation (parallel or antiparallel to the direction of momentum) provide considerable simplification in calculations. Hence, it is generally preferred to use helicity basis during the calculations in Relativistic Quantum Mechanics or Quantum Field Theory. Possibly because of the above reason, the Dirac spinors describing a general spin orientation have been ignored in many textbooks. Although the helicity eigenstates give almost complete understanding of the behavior of the free Dirac solutions, the zero-mass limit is one of its exception. It is well known that the helicity eigenstates converge to the chirality eigenstates in the zero-mass limit. It is very common to assume that this result is not specific to helicity eigenstates, but valid in general. On the contrary, the free spinor with general spin orientation does not converge to one of the chirality eigenstate or equivalently is not described by one of the Weyl equations, in the...

  14. Spin orientation driven static and dynamic magnetic process in amorphous FeCoBSi thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Peiheng; Luo, Xiaojia; Zhang, Li; Lu, Haipeng; Xie, Jianliang; Deng, Longjiang [State Key Laboratory of Electronic Thin Film and Integrated Devices, National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-06-07

    The spin orientation dependence of magnetic hysteresis and microwave ferromagnetic resonance data are investigated in FeCoBSi amorphous thin films. Demagnetization effect allows the weak interface-rooted out-of-plane anisotropy to build up local spin orientation domains under the dominant in-plane anisotropy. As a result, two phase magnetization reversal and double-peak ferromagnetic resonance traces with varying damping behavior are observed. Due to the distribution of in-plane and out-of-plane spin orientations, the ferromagnetic resonance bandwidth has been extensively expanded with the full width at half maximum increased from 1.2 GHz to 3.5 GHz.

  15. Control of Spin Helix Symmetry in Semiconductor Quantum Wells by Crystal Orientation

    Science.gov (United States)

    Kammermeier, Michael; Wenk, Paul; Schliemann, John

    2016-12-01

    We investigate the possibility of spin-preserving symmetries due to the interplay of Rashba and Dresselhaus spin-orbit coupling in n -doped zinc-blende semiconductor quantum wells of general crystal orientation. It is shown that a conserved spin operator can be realized if and only if at least two growth direction Miller indices agree in modulus. The according spin-orbit field has in general both in-plane and out-of-plane components and is always perpendicular to the shift vector of the corresponding persistent spin helix. We also analyze higher-order effects arising from the Dresselhaus term, and the impact of our results on weak (anti)localization corrections.

  16. Monopolar diathermy used for correction of ankyloglossia

    Directory of Open Access Journals (Sweden)

    Tuli A

    2010-06-01

    Full Text Available Tongue tie, also known as ankyloglossia or ankyloglossia inferior, is a relatively common finding in pediatric surgical outpatient clinics. It occurs as a result of a short, tight, lingual frenum causing tethering of the tongue tip. It is a common oral finding in infants and children, which is often neglected. Although most cases resolve or are asymptomatic, some patients develop articulation problems and other concerns related to poor tongue-tip mobility. In this article, we report on a 5-year old girl with a tongue tie, who underwent frenectomy using monopolar diathermy under local anesthesia without any postoperative complication.

  17. Zero-mass limit of a Dirac spinor with general spin orientation

    Science.gov (United States)

    Şahin, İ.

    2016-11-01

    The helicity eigenstates that describe fermions with a special spin orientation (parallel or antiparallel to the direction of momentum) provide a considerable simplification in calculations. Hence, it is generally preferred to use the helicity basis during calculations in relativistic quantum mechanics or the quantum field theory. Possibly for the above reason, Dirac spinors describing a general spin orientation have been ignored in many textbooks. Although the helicity eigenstates give an almost complete understanding of the behavior of the free Dirac solutions, the zero-mass limit is one of its exceptions. The zero-mass behavior of the free spinor with general spin orientation and its relation with chirality eigenstates has been skipped in textbooks and hence it deserves a clear, detailed investigation. In this paper we obtain the free Dirac spinors describing a general spin orientation and examine their zero-mass limit. We also briefly discuss some of the implications of this small-mass behavior of the spinors on particle physics.

  18. Test of the universality of free fall with atoms in different spin Orientations

    CERN Document Server

    Duan, Xiao-Chun; Deng, Xiao-Bing; Yao, Hui-Bin; Shao, Cheng-Gang; Luo, Jun; Hu, and Zhong-Kun

    2015-01-01

    We report a test of the universality of free fall (UFF) related to spin-gravity coupling effects by comparing the gravity acceleration of the $^{87}$Rb atoms in $m_F=+1$ versus that in $m_F=-1$, where the corresponding spin orientations are opposite. A Mach-Zehnder-type atom interferometer is exploited to sequentially measure the free fall acceleration of the atoms in these two sublevels, and the resultant E$\\rm{\\ddot{o}}$tv$\\rm{\\ddot{o}}$s ratio determined by this work is ${\\eta_S} =(-0.2\\pm1.5)\\times 10^{-5}$. The interferometer using atoms in $m_F=+1$ or $m_F=-1$ is highly sensitive to magnetic field inhomogeneity, which limits the current experimental precision of our UFF test. The work here provides a stepping stone for future higher precision UFF test related to different spin orientations on atomic basis.

  19. Sign determination of dipolar couplings in field-oriented bicelles by variable angle sample spinning (VASS)

    Energy Technology Data Exchange (ETDEWEB)

    Tian, F.; Losonczi, J.A.; Fischer, M.W.F.; Prestegard, J.H. [University of Georgia, Complex Carbohydrate Research Center (United States)

    1999-10-15

    Residual dipolar couplings are being increasingly used as structural constraints for NMR studies of biomolecules. A problem arises when dipolar coupling contributions are larger than scalar contributions for a given spin pair, as is commonly observed in solid state NMR studies, in that signs of dipolar couplings cannot easily be determined. Here the sign ambiguities of dipolar couplings in field-oriented bicelles are resolved by variable angle sample spinning (VASS) techniques. The director behavior of field-oriented bicelles (DMPC/DHPC, DMPC/CHAPSO) in VASS is studied by {sup 31}P NMR. A stable configuration occurs when the spinning angle is smaller than the magic angle, 54.7 deg., and the director (or bicelle normal) of the disks is mainly distributed in a plane perpendicular to the rotation axis. Since the dipolar couplings depend on how the bicelles are oriented with respect to the magnetic field, it is shown that the dipolar interaction can be scaled to the same order as the J-coupling by moving the spinning axis from 0 deg. toward 54.7 deg. Thus the relative sign of dipolar and scalar couplings can be determined.

  20. The preferred orientation of Mn3 spins in magnetic multiferroic CaMn7O12

    Science.gov (United States)

    Dai, Jian-Qing; Zhang, Hu; Song, Yu-Min

    2015-12-01

    The remarkable ferroelectricity in CaMn7O12 originates from the helicoidal spin spiral, in which the Mn3 (3b Wyckoff position) spin direction remains controversial. In this paper, the total energy, phase transition path, and spontaneous polarization of CaMn7O12 are investigated by using first-principle methods. We show that, in order to account for the giant electric polarization and the correct phase transition sequence, the relative orientation between the spins of Mn3 and Mn2 (9d Wyckoff position) sites with the same coordinate along the hexagonal c-axis can not be antiparallel, i.e. their relative orientation angle should be ϕ≈0.84π instead of ϕ=π. The most likely reason for the observation of ϕ=π can be attributed to the withdrawal of spin-orbital coupling between the Mn2 and Mn3 spins, which is caused by doping Cu2+ in the samples for neutron powder diffraction measurements.

  1. Swerving Orientation of Spin-Stabilized Projectile for Fixed-Cant Canard Control Input

    Directory of Open Access Journals (Sweden)

    Xu-dong Liu

    2015-01-01

    Full Text Available Due to the large launch overload and high spin rate of spin-stabilized projectile, no attitude sensor is adopted in square crossing fixed-cant canard concept, which causes the lack of existing projectile linear theory for the close form solution of swerving motion. This work focuses on swerving orientation prediction with the restricted conditions. By importing the mathematical models of canard force and moment into the projectile angular motion equations, trim angle induced by canard control force is extracted as the analytical solution of angle of attack increment (AOAI. On this basis, analytical orientations of trajectory angular rate increment and swerving increment are obtained via the frozen coefficient method. A series of simulations under different conditions were implemented to validate the expressions in this effort. Results state that increment orientation of swerving motion can be predicted with available trajectory parameters. The analytical orientations indicate trim value of numerical orientations. Deviations between analytical and numerical orientations relate to initial launch angles and control start time, both lower initial launch angle, and the start time which is closer to the end of flight decreases the deviation convergence time.

  2. Monopolar intracochlear pulse trains selectively activate the inferior colliculus.

    Science.gov (United States)

    Schoenecker, Matthew C; Bonham, Ben H; Stakhovskaya, Olga A; Snyder, Russell L; Leake, Patricia A

    2012-10-01

    Previous cochlear implant studies using isolated electrical stimulus pulses in animal models have reported that intracochlear monopolar stimulus configurations elicit broad extents of neuronal activation within the central auditory system-much broader than the activation patterns produced by bipolar electrode pairs or acoustic tones. However, psychophysical and speech reception studies that use sustained pulse trains do not show clear performance differences for monopolar versus bipolar configurations. To test whether monopolar intracochlear stimulation can produce selective activation of the inferior colliculus, we measured activation widths along the tonotopic axis of the inferior colliculus for acoustic tones and 1,000-pulse/s electrical pulse trains in guinea pigs and cats. Electrical pulse trains were presented using an array of 6-12 stimulating electrodes distributed longitudinally on a space-filling silicone carrier positioned in the scala tympani of the cochlea. We found that for monopolar, bipolar, and acoustic stimuli, activation widths were significantly narrower for sustained responses than for the transient response to the stimulus onset. Furthermore, monopolar and bipolar stimuli elicited similar activation widths when compared at stimulus levels that produced similar peak spike rates. Surprisingly, we found that in guinea pigs, monopolar and bipolar stimuli produced narrower sustained activation than 60 dB sound pressure level acoustic tones when compared at stimulus levels that produced similar peak spike rates. Therefore, we conclude that intracochlear electrical stimulation using monopolar pulse trains can produce activation patterns that are at least as selective as bipolar or acoustic stimulation.

  3. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  4. Orientational glass: Full replica symmetry breaking in generalized spin glass-like models without reflection symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Tareyeva, E.E. [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); Schelkacheva, T.I., E-mail: tanschelk@gmail.com [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); Chtchelkatchev, N.M. [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 117940 Moscow (Russian Federation); Department of Theoretical Physics, Moscow Institute of Physics and Technology, 141700 Moscow (Russian Federation)

    2013-02-15

    We investigate near the point of glass transition the expansion of the free energy corresponding to the generalized Sherrington–Kirkpatrick model with arbitrary diagonal operators U{sup -hat} standing instead of Ising spins. We focus on the case when U{sup -hat} is an operator with broken reflection symmetry. Such a consideration is important for understanding the behavior of spin glass-like phases in a number of real physical systems, mainly in orientational glasses in mixed molecular crystals which present just the case. We build explicitly a full replica symmetry breaking (FRSB) solution of the equations for the orientational glass order parameters when the nonsymmetric part of U{sup -hat} is small. This particular result presents a counterexample in the context of usually adopted conjecture of the absence of FRSB solution in systems with no reflection symmetry.

  5. Orientational glass: Full replica symmetry breaking in generalized spin glass-like models without reflection symmetry

    Science.gov (United States)

    Tareyeva, E. E.; Schelkacheva, T. I.; Chtchelkatchev, N. M.

    2013-02-01

    We investigate near the point of glass transition the expansion of the free energy corresponding to the generalized Sherrington-Kirkpatrick model with arbitrary diagonal operators Uˆ standing instead of Ising spins. We focus on the case when Uˆ is an operator with broken reflection symmetry. Such a consideration is important for understanding the behavior of spin glass-like phases in a number of real physical systems, mainly in orientational glasses in mixed molecular crystals which present just the case. We build explicitly a full replica symmetry breaking (FRSB) solution of the equations for the orientational glass order parameters when the nonsymmetric part of Uˆ is small. This particular result presents a counterexample in the context of usually adopted conjecture of the absence of FRSB solution in systems with no reflection symmetry.

  6. Optical spin orientation in (110)GaAs quantum wells at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lombez, L.; Lagarde, D.; Renucci, P.; Amand, T.; Marie, X. [Laboratoire de Nanophysique, Magnetisme et Optoelectronique, INSA, 135 avenue de Rangueil, 31077 Toulouse Cedex 4 (France); Liu, B.L.; Chen, D.M. [Solid State Quantum Information and Computation, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Wang, W.X.; Xue, Q.K. [State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-07-01

    We used time-resolved optical orientation experiments to study the spin dynamics in (110) oriented GaAs/Al{sub 0.4}GaAs quantum wells at room temperature. We observe a clear dependence of the initial spin polarisation P(0) and of the polarisation decay time {tau}{sub s} as a function of the excitation wavelength and power. As high values as P(0){proportional_to} 80% and {tau}{sub s} {proportional_to}1.6 ns have been observed when exciting quasi-resonantly with the heavy-hole transition. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Spin axis orientation of Ajisai determined from Graz 2 kHz SLR data

    Science.gov (United States)

    Kucharski, D.; Otsubo, T.; Kirchner, G.; Koidl, F.

    2010-08-01

    The Graz 2 kHz Satellite Laser Ranging (SLR) measurements allow determination of the spin axis orientation of the geodetic satellite Ajisai. The high repetition rate of the laser makes it possible to determine the epoch time when the laser is pointing directly between two corner cube reflector (CCR) rings of the satellite. Identification of many such events during a few (up to 3) consecutive passes allows to state the satellite orientation in the celestial coordinate system. Six years of 2 kHz SLR data (October 2003-October 2009) delivered 331 orientation values which clearly show precession of the axis along a cone centered at 14 h56 m2.8 s in right ascension and 88.512° in declination (J2000.0 celestial reference frame) and with an half-aperture angle θ of 1.405°. The spin axis precesses with a period of 117 days, which is equal to the period of the right ascension of the ascending node of Ajisai's orbit. We present a model of the axis precession which allows prediction of the satellite orientation - necessary for the envisaged laser time transfer via Ajisai mirrors.

  8. Stern-Gerlach Experiments on Mn@Sn12: Identification of a Paramagnetic Superatom and Vibrationally Induced Spin Orientation

    Science.gov (United States)

    Rohrmann, Urban; Schäfer, Rolf

    2013-09-01

    Beam deflection experiments in inhomogeneous magnetic fields reveal a new limiting case of the magnetization distribution of isolated clusters. Endohedrally doped clusters are produced in a temperature controlled, cryogenically cooled laser ablation source. Temperature dependent experiments indicate a crucial contribution of molecular vibrations to the spin dynamics of Mn@Sn12. In its vibrational ground state the cluster behaves magnetically like a paramagnetic atom, with quantized spin states. However, excited molecular vibrations induce spin orientation in the magnetic field.

  9. Earth Reflected Solar Radiation Incident upon an Arbitrarily Oriented Spinning Flat Plate

    Science.gov (United States)

    Cunningham, Fred G.

    1963-01-01

    A general derivation is given for the earth reflected solar radiation input to a flat plate--a solar cell paddle, for example--which is spinning about an axis coincident with the axis of symmetry of the satellite to which it is affixed. The resulting equations are written for the general case so that arbitrary orientations of the spin axis with respect to the earth-satellite line and arbitrary orientations of the normal to the plate with respect to the spin axis can be treated. No attempt is made to perform the resulting integrations because of the complexity of the equations; nor is there any attempt to delineate the integration limits for the general case. However, the equations governing these limits are given. The appendixes contain: the results, in graphical form, of two representative examples; the general computer program for the calculation is given in Fortran notation; and the results of a calculation of the distribution of albedo energy on the proposed Echo II satellite. The value of the mean solar constant used is 1.395 times 10 (sup 4) ergs per centimeters-squared per second; the mean albedo of the earth is assumed to be 0.34; and the earth is assumed to be a diffuse reflector.

  10. DeSSpOt: an instrument for stellar spin orientation determination

    Science.gov (United States)

    Lesage, Anna-Lea; Schneide, Magnus; Wiedemann, Günter

    2012-09-01

    We designed and constructed a special instrument to enable the determination of the stellar's spin orientation. The Differential image rotator for Stellar Spin Orientation, DeSSpOt, allows the simultaneous observations of two anti-parallel orientations of the star on the spectrum. On a high resolution échelle spectrum, the stellar rotation causes a slight line tilt visible in the spatial direction which is comparable to a rotation curve. We developed a new method, which exploits the variations in these tilts, to estimate the absolute position angle of the rotation axis. The line tilt is retrieved by a spectroastrometric extraction of the spectrum. In order to validate the method, we observed spectroscopic binaries with known orbital parameters. The determination of the orbital position angle is equivalent to the determination of the stellar position angle, but is easier to to detect. DeSSpOt was successfully implemented on the high resolution Coudé spectrograph of the Thüringer Landessternwarte Tautenburg. The observations of Capella led to the determination of the orbital position angle. Our value of 37.2° is in agreement with the values previously found in the literature. As such we verified that both method and instrument are valid.

  11. DeSSpOt: an instrument for stellar spin orientation determination

    CERN Document Server

    Lesage, Anna-Lea; Wiedemann, Günter

    2012-01-01

    We designed and constructed a special instrument to enable the determination of the stellar's spin orientation. The Differential image rotator for Stellar Spin Orientation, DeSSpOt, allows the simultaneous observations of two anti-parallel orientations of the star on the spectrum. On a high resolution \\'echelle spectrum, the stellar rotation causes a slight line tilt visible in the spatial direction which is comparable to a rotation curve. We developed a new method, which exploits the variations in these tilts, to estimate the absolute position angle of the rotation axis. The line tilt is retrieved by a spectro-astrometric extraction of the spectrum. In order to validate the method, we observed spectroscopic binaries with known orbital parameters. The determination of the orbital position angle is equivalent to the determination of the stellar position angle, but is easier to to detect. DeSSpOt was successfully implemented on the high resolution Coud\\'e spectrograph of the Th\\"uringer Landessternwarte Tautenb...

  12. Pulse-fluence-specified optimal control simulation with applications to molecular orientation and spin-isomer-selective molecular alignment

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Masataka; Nakashima, Kaoru; Ohtsuki, Yukiyoshi [Department of Chemistry, Graduate School of Science, Tohoku University 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

    2015-12-31

    We propose an optimal control simulation with specified pulse fluence and amplitude. The simulation is applied to the orientation control of CO molecules to examine the optimal combination of THz and laser pulses, and to discriminate nuclear-spin isomers of {sup 14}N{sub 2} as spatially anisotropic distributions.

  13. The preferred orientation of Mn3 spins in magnetic multiferroic CaMn{sub 7}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jian-Qing, E-mail: djqkust@sina.com; Zhang, Hu; Song, Yu-Min

    2015-12-15

    The remarkable ferroelectricity in CaMn{sub 7}O{sub 12} originates from the helicoidal spin spiral, in which the Mn3 (3b Wyckoff position) spin direction remains controversial. In this paper, the total energy, phase transition path, and spontaneous polarization of CaMn{sub 7}O{sub 12} are investigated by using first-principle methods. We show that, in order to account for the giant electric polarization and the correct phase transition sequence, the relative orientation between the spins of Mn3 and Mn2 (9d Wyckoff position) sites with the same coordinate along the hexagonal c-axis can not be antiparallel, i.e. their relative orientation angle should be ϕ≈0.84π instead of ϕ=π. The most likely reason for the observation of ϕ=π can be attributed to the withdrawal of spin–orbital coupling between the Mn2 and Mn3 spins, which is caused by doping Cu{sup 2+} in the samples for neutron powder diffraction measurements. - Highlights: • In CaMn{sub 7}O{sub 12}, the preferred orientation angle of the Mn3 spins remains controversial. • The relative orientation angle between Mn3 and Mn2 spins should be 0.84π instead of π. • For ϕ=π, phase transition path and polarization are inconsistent with experiments. • The reason for observation of ϕ=π is due to Cu{sup 2+}-doping in the experimental samples.

  14. Dependence of improper ferroelectricity on the preferred orientation of Mn3 spins in CaMn7O12

    Science.gov (United States)

    Dai, Jian-Qing

    2017-02-01

    The improper ferroelectricity of CaMn7O12 is studied by examining the influence of the orientation angle of Mn3 spins on the basis of first-principles density functional theory. We analyze the helicoidal magnetic order induced forces, ionic displacements, and polarization contributions from both atomic and mode- decomposition viewpoints. Our work unambiguously reveals the critical role of the orientation angle of Mn3 spins in determining the improper ferroelectricity of CaMn7O12. The ferroelectric polarization can be reversed by changing the orientation angle of Mn3 spins without switching spin chirality of the helicoidal magnetic order. We demonstrate that the particular helicoidal magnetic order induces remarkable mismatch of the Born effective charges with the lattice symmetry, which leads to the dominant contribution to ferroelectric polarization from purely Raman-type ionic displacements. However, this significant polarization contribution from the purely Raman-type distortion cannot survive in the absence of IR-active ionic displacements.

  15. The Complex Spin State of 103P-Hartley 2: Kinematics and Orientation in Space

    Science.gov (United States)

    Belton, Michael J. S.; Thomas, Peter; Li, Jian-Yang; Williams, Jade; Carcich, Brian; A'Hearn, Michael F.; McLaughlin, Stephanie; Farnham, Tony; McFadden, Lucy; Lisse, Carey M.; Collins, Steven; Besse, Sebastien; Klaasen, Kenneth; Sunshine, Jessica; Meech, Karen J.; Lindler, Don

    2013-01-01

    We derive the spin state of the nucleus of Comet 103P/Hartley 2, its orientation in space, and its short-term temporal evolution from a mixture of observations taken from the DIXI (Deep Impact Extended Investigation) spacecraft and radar observations. The nucleus is found to spin in an excited long-axis mode (LAM) with its rotational angular momentum per unit mass, M, and rotational energy per unit mass, E, slowly decreasing while the degree of excitation in the spin increases through perihelion passage. M is directed toward (RA, Dec; J2000) = 8+/-+/- 4 deg., 54 +/- 1 deg. (obliquity = 48 +/- 1 deg.). This direction is likely changing, but the change is probably <6 deg. on the sky over the approx. 81.6 days of the DIXI encounter. The magnitudes of M and E at closest approach (JD 2455505.0831866 2011-11-04 13:59:47.310) are 30.0 +/- 0.2 sq. m/s and (1.56 +/- 0.02) X 10(exp -3) sq. m /sq. s respectively. The period of rotation about the instantaneous spin vector, which points in the direction (RA, Dec; J2000) = 300 +/- 3.2deg., 67 +/- 1.3 deg. at the time of closest approach, was 14.1 +/- 0.3 h. The instantaneous spin vector circulates around M, inclined at an average angle of 33.2 +/- 1.3 deg. with an average period of 18.40 +/- 0.13 h at the time of closest approach. The period of roll around the principal axis of minimum inertia (''long'' axis) at that time is 26.72 +/- 0.06 h. The long axis is inclined to M by approx. 81.2 +/- 0.6 deg. on average, slowly decreasing through encounter. We infer that there is a periodic nodding motion of the long axis with half the roll period, i.e., 13.36+/- 0.03 h, with amplitude of 1 again decreasing through encounter. The periodic variability in the circulation and roll rates during a cycle was at the 2% and 10-14% level respectively. During the encounter there was a secular lengthening of the circulation period of the long axis by 1.3 +/- 0.2 min/d, in agreement with ground-based estimates, while the period of roll around the

  16. Day care monopolar transurethral resection of prostate: Is it feasible?

    Directory of Open Access Journals (Sweden)

    Altaf Khan

    2014-01-01

    Full Text Available Introduction: Benign prostatic hyperplasia is a common disease accounting for 30% of our OPD cases and about 25% of our surgery cases. Various treatment options are now available for more efficient care and early return to work. We wanted to determine the safety and feasibility of day care monopolar transurethral resection of prostate (m-TURP, by admitting the patients on the day of surgery and discharging the patient without catheter on the same day. We also compared the morbidity associated with conventional TURP where in the catheter is removed after 24-48 h of surgery and day care TURP where in the catheter is removed on the day of surgery. Materials and Methods: A total of 120 patients who fulfilled the criteria were included in the study which was conducted between November 2008 and December 2010. A total of 60 patients were assigned for day care and 60 for conventional monopolar TURP. There was no significant difference in age, prostatic volume or IPSS score. Day care patients were admitted on day of surgery and discharged the same day after the removal of catheter. Results: Both the groups were comparable in outcome. Stricture rate was less with day care TURP. Mean catheterization time was similar to laser TURP. Conclusion: Monopolar TURP is still the gold standard of care for BPH. If cases are selected properly and surgery performed diligently it remains the option of choice for small and medium sized glands and patients can be back to routine work early.

  17. Test of the universality of free fall with atoms in different spin orientations

    CERN Document Server

    Duan, Xiao-Chun; Zhou, Min-Kang; Zhang, Ke; Xu, Wen-Jie; Xiong, Feng; Xu, Yao-Yao; Shao, Cheng-Gang; Luo, Jun; Hu, Zhong-Kun

    2016-01-01

    We report a test of the universality of free fall (UFF) by comparing the gravity acceleration of the $^{87}$Rb atoms in $m_F=+1$ versus that in $m_F=-1$, where the corresponding spin orientations are opposite. A Mach-Zehnder-type atom interferometer is exploited to sequentially measure the free fall acceleration of the atoms in these two magnetic sublevels, and the resultant E$\\rm{\\ddot{o}}$tv$\\rm{\\ddot{o}}$s ratio is ${\\eta _S} =(0.2\\pm1.2)\\times 10^{-7}$. This also gives an upper limit of $1.1\\times 10^{-21}$ GeV/m for possible gradient field of the spacetime torsion. The interferometer using atoms in $m_F=\\pm 1$ is highly sensitive to the magnetic field inhomogeneity, and a double differential measurement method is developed to alleviate the inhomogeneity influence. Moreover, a proof experiment by modulating the magnetic field is performed, which validates the alleviation of the inhomogeneity influence in our test.

  18. Discovery of room-temperature spin-glass behaviors in two-dimensional oriented attached single crystals

    Science.gov (United States)

    Ma, Ji; Chen, Kezheng

    2016-05-01

    In this study, room-temperature spin-glass behaviors were observed in flake-like oriented attached hematite (α-Fe2O3) and iron phosphate hydroxide hydrate (Fe5(PO4)4(OH)3·2H2O) single crystals. Remarkably, their coercivity (HC) values were found to be almost invariable at various given temperatures from 5 to 300 K. The spin topographic map in these flakes was assumed as superparamagnetic (SPM) "islands" isolated by spin glass (SG)-like "bridges". A spin-glass model was then proposed to demonstrate the spin frustration within these "bridges", which were formed by the staggered atomic planes in the uneven surfaces belonging to different attached nanoparticles. Under the spatial limitation and coupling shield of these "bridges", the SPM "islands" were found to be collectively frozen to form a superspin glass (SSG) state below 80 K in weak applied magnetic fields; whereas, when strong magnetic fields were applied, the magnetic coupling of these "islands" would become superferromagnetic (SFM) through tunneling superexchange, so that, these SFM spins could antiferromagnetically couple with the SG-like "bridges" to yield pronounced exchange bias (EB) effect.

  19. Communication: Orientational self-ordering of spin-labeled cholesterol analogs in lipid bilayers in diluted conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kardash, Maria E.; Dzuba, Sergei A., E-mail: dzuba@kinetics.nsc.ru [Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia, and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2014-12-07

    Lipid-cholesterol interactions are responsible for different properties of biological membranes including those determining formation in the membrane of spatial inhomogeneities (lipid rafts). To get new information on these interactions, electron spin echo (ESE) spectroscopy, which is a pulsed version of electron paramagnetic resonance (EPR), was applied to study 3β-doxyl-5α-cholestane (DCh), a spin-labeled analog of cholesterol, in phospholipid bilayer consisted of equimolecular mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine. DCh concentration in the bilayer was between 0.1 mol.% and 4 mol.%. For comparison, a reference system containing a spin-labeled 5-doxyl-stearic acid (5-DSA) instead of DCh was studied as well. The effects of “instantaneous diffusion” in ESE decay and in echo-detected (ED) EPR spectra were explored for both systems. The reference system showed good agreement with the theoretical prediction for the model of spin labels of randomly distributed orientations, but the DCh system demonstrated remarkably smaller effects. The results were explained by assuming that neighboring DCh molecules are oriented in a correlative way. However, this correlation does not imply the formation of clusters of cholesterol molecules, because conventional continuous wave EPR spectra did not show the typical broadening due to aggregation of spin labels and the observed ESE decay was not faster than in the reference system. So the obtained data evidence that cholesterol molecules at low concentrations in biological membranes can interact via large distances of several nanometers which results in their orientational self-ordering.

  20. Spin orientation in an ultrathin CoO/PtFe double-layer with perpendicular exchange coupling

    Energy Technology Data Exchange (ETDEWEB)

    Lamirand, Anne D.; Soares, Márcio M. [Institut Néel, CNRS and UJF, BP166, 38042 Grenoble (France); Ramos, Aline Y., E-mail: aline.ramos@grenoble.cnrs.fr [Institut Néel, CNRS and UJF, BP166, 38042 Grenoble (France); Tolentino, Hélio C.N.; De Santis, Maurizio [Institut Néel, CNRS and UJF, BP166, 38042 Grenoble (France); Cezar, Julio C. [Laboratório Nacional de Luz Síncrotron-LNLS, CP 6192, 13083-970 Campinas (Brazil); Siervo, Abner de [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, 13083-970 Campinas (Brazil)

    2015-01-01

    We studied by soft X-ray absorption spectroscopy the magnetization axis in a 4 nm thin CoO (111) layer exchange-coupled to an ultra thin L1{sub 0} PtFe layer with perpendicular magnetic anisotropy. The angular dependence of the linear magnetic dichroism at 10 K and the relative variations of the spectral features provide a full description of the spin orientation in this antiferromagnetic layer. The spins are found in the film plane, pointing along the 110 direction. This results is discussed in relation to the film strain and the preferential occupation of t{sub 2g} orbitals. The strong orthogonal coupling between Co and Fe spins should be at the origin of the robustness of the exchange bias effect found in this bilayer system.

  1. The orientation risk in investing in university spin-offs. Does it exist? Is it possible to identify it during the spin-offs´ first years?

    Directory of Open Access Journals (Sweden)

    Julio Pombo Romero

    2016-04-01

    Full Text Available A number of studies are showing that companies created from universities (USO have a relatively low growth rate in relation to other start-ups. This may be due to the fact that a significant proportion of USOs can be set up in order to give continuity to research projects on the basis of public aid rather than to commercialize research results in the market. The main objective of this work is to discuss whether it is possible or not to differentiate two types of USO regarding their orientation to the market. We also check the possibility of identifying this difference in the earlier stages of the spin-offs because it would affect the company´s risk level from the investors’ perspective. In order to study this, we identified a sample of 20 spin-offs and recorded their economic information during their first 5 years of life. We also tracked the number and amount of public grants and subsidies obtained during this period. The hypothesis of the article was tested using cluster analysis. The results obtained indicate the existence of two different types of USO regarding a market orientated business model or one that is not. This difference cannot be identified from the financial statements of the USO in its earliest stages. These facts can originate “orientation risk” defined as the impossibility for the investor in USOs to identify, in its earlier stages, if the company will end up oriented to the market or not.

  2. Perceptual Interactions Between Electrodes Using Focused and Monopolar Cochlear Stimulation

    DEFF Research Database (Denmark)

    Marozeau, Jeremy; McDermott, Hugh J.; Swanson, Brett A.;

    2015-01-01

    to implement an all-polar (AP) stimulation mode designed to create a focused electrical field. The goal of this experiment was to study the potential benefits of this all-polar mode for reducing uncontrolled electrode interactions compared with the monopolar mode. The five participants who took part......-matched sequential and simultaneous stimuli composed of 2 spatially separated pulse trains was measured as function of the electrode separation. Results indicated a strong current-summation interaction for simultaneous stimuli in the MP mode for separations up to at least 4.8 mm. No significant interaction was found...

  3. Spin-Orbit induced semiconductor spin guides

    OpenAIRE

    Valin-Rodriguez, Manuel; Puente, Antonio; Serra, Llorens

    2002-01-01

    The tunability of the Rashba spin-orbit coupling allows to build semiconductor heterostructures with space modulated coupling intensities. We show that a wire-shaped spin-orbit modulation in a quantum well can support propagating electronic states inside the wire only for a certain spin orientation and, therefore, it acts as an effective spin transmission guide for this particular spin orientation.

  4. [Study on the orientation of liquid crystals presented on the glass substrates spin-coated and functionalized with copper ions].

    Science.gov (United States)

    Wang, Shiming; Xiong, Xingliang; Zhang, Yan; Li, Guang; Chen, Mengmeng

    2013-06-01

    A stable, uniform, easily implemented, LC-based chemical and biological sensor substrate for orientations of liquid crystals (LCs) for a long-term is urgently needed for medical applications of the sensors. We proposed a use of spin-coating of copper perchlorate (Cu(ClO4)2), with five different concentrations(0-100mmol/L), directly on glass slides for fabricating a layer of chemically-sensitive copper ions. Observing the transmitted light with a polarized microscope, we found the luminosity of the light propagated through sensors deposited with copper ions started to weaken gradually after a certain time. The higher was the concentration of copper ions covered on the glass substrates of the sensors, the faster the weakening occurred, and the less time was needed for transmitted light to turn completely dark. But there was no change in luminosity of the transmitted light for the sensors without Cu(ClO4)2 spin-coating even after stored at room temperature (25 degrees C) for a whole day. When the Cu(ClO4)2 deposited sensors were stored within a drying oven at room temperature (25 degrees C) for 2 months, it was found that there vas almost no change in luminosity of the transmitted lights. The results showed that all the thin films of LC on glass slides functionalized with Cu(ClO4)2 could keep homeotropic and stable orientation for a long time; the concentration of Cu (ClO4)2I has an influence on the orientation response speed of LC from planar to perpendicular orientation.

  5. Effect of core--mantle and tidal torques on Mercury's spin axis orientation

    CERN Document Server

    Peale, Stanton J; Hauck,, Steven A; Solomon, Sean C

    2014-01-01

    The rotational evolution of Mercury's mantle and its core under conservative and dissipative torques is important for understanding the planet's spin state. Dissipation results from tides and viscous, magnetic and topographic core--mantle interactions. The dissipative core--mantle torques take the system to an equilibrium state wherein both spins are fixed in the frame precessing with the orbit, and in which the mantle and core are differentially rotating. This equilibrium exhibits a mantle spin axis that is offset from the Cassini state by larger amounts for weaker core--mantle coupling for all three dissipative core--mantle coupling mechanisms, and the spin axis of the core is separated farther from that of the mantle, leading to larger differential rotation. The relatively strong core--mantle coupling necessary to bring the mantle spin axis to its observed position close to the Cassini state is not obtained by any of the three dissipative core--mantle coupling mechanisms. For a hydrostatic ellipsoidal core...

  6. Membrane module and process development for monopolar and bipolar membrane electrodialysis

    OpenAIRE

    Balster, Jörg Henning

    2006-01-01

    This thesis aims to develop more efficient monopolar and bipolar membrane electrodialysis processes. Three main topics have been investigated: 1. Membrane selectivity 2. Concentration polarisation 3. Membrane scaling and fouling

  7. Role of hyperfine interaction on electron spin optical orientation in charge-controlled InAs-GaAs single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, O.; Eble, B.; Lemaitre, A.; Kudelski, A.; Voisin, P. [Laboratoire de Photonique et Nanostructures-CNRS, Route de Nozay, 91460 Marcoussis (France); Urbaszek, B.; Marie, X.; Amand, T. [Laboratoire de Nanophysique Magnetisme et Optoelectronique, INSA, 31077 Toulouse Cedex 4 (France); Kowalik, K. [Laboratoire de Photonique et Nanostructures-CNRS, Route de Nozay, 91460 Marcoussis (France); Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw (Poland)

    2007-01-15

    We report on electron spin physics in a single charge-tunable self-assembled InAs/GaAs quantum dot. The hyperfine interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser-shift depends on the trion state X{sup +} or X{sup -}, and remarkably its strength does not vanish in zero magnetic field. This explains the quenching of X{sup +} spin relaxation under steady-state excitation polarization. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Stability and phase separation in mixed monopolar lipid/bolalipid layers.

    Science.gov (United States)

    Longo, Gabriel S; Thompson, David H; Szleifer, I

    2007-10-15

    The phase stability of a fluid lipid layer that is a mixture of conventional monopolar lipids and C20 bipolar bolalipids was studied using a mean field theory that explicitly includes molecular details and configurational properties of the lipid molecules. The effect of changing the fraction of bolalipids, as well as the length of the hydrocarbon chain of the monopolar lipids, was probed. A phase separation between two liquid lipid phases was found when a mismatch exists in the optimal hydrophobic thicknesses of the pure bolalipid and monopolar lipid layers. The lipid mixture phase separates into a thin bolalipid-rich layer and a thicker monopolar-rich layer. The thin membrane phase is mainly composed of transmembrane bolalipid molecules whose polar heads are positioned at opposite membrane-water interfaces. In the monopolar lipid-rich phase, bolalipids are the minor component and most of them assume a looping configuration where both headgroups are present at the same membrane-water interface. For mixed layers that form a single lipid phase across all bolalipid concentrations, the hairpin-transmembrane ratio strongly depends on the hydrocarbon chain length of the monopolar lipid and the bolalipid concentration. The C-D bond order parameters of the different species have been calculated. Our findings suggest that the concentration-dependent phase transition should be experimentally observable by measuring of the order parameters through quadrupolar splitting experiments. The driving force for the phase separation in the monopolar lipid/bolalipid mixture is the packing mismatch between hydrophobic regions of the monopolar lipid hydrocarbon chains and the membrane-spanning bolalipid chains. The results from the molecular theory may be useful in the design of stable lipid layers for integral membrane protein sensing.

  9. Postoperative Adhesion Formation in a Rabbit Model: Monopolar Electrosurgery Versus Ultrasonic Scalpel

    Science.gov (United States)

    Lazarou, George; Apostol, Radu; Khullar, Poonam; Okonkwo, Linda; Nezhat, Farr

    2015-01-01

    Background and Objectives: To determine if surgery using ultrasonic energy for dissection results in less adhesion formation than monopolar electrosurgical energy in the late (8 weeks) postoperative period. Methods: Injuries were induced in rabbits by using ultrasonic energy on one uterine horn and the adjacent pelvic sidewall and using monopolar energy on the opposite side. Eight weeks postoperatively, the rabbits underwent autopsy and clinical and pathologic scoring of adhesions was performed by blinded investigators. Results: There was no significant difference in clinical adhesion scores between the two modalities. The mean clinical score for monopolar cautery was 1.00 versus 0.88 for the Harmonic device (Ethicon Endo-Surgery, Cincinnati, Ohio) (P = .71). Furthermore, there was no significant difference found in the pathologic adhesion scores between the ultrasonic scalpel and monopolar energy. The mean pathologic score for monopolar electrosurgery was 4.35 versus 3.65 for the Harmonic scalpel (P = .30). Conclusion: Neither monopolar electrosurgery nor ultrasonic dissection is superior in the prevention of adhesion formation in the late postoperative period. PMID:26005316

  10. Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object's spin-axis orientation

    Science.gov (United States)

    Müller, T. G.; Ďurech, J.; Ishiguro, M.; Mueller, M.; Krühler, T.; Yang, H.; Kim, M.-J.; O'Rourke, L.; Usui, F.; Kiss, C.; Altieri, B.; Carry, B.; Choi, Y.-J.; Delbo, M.; Emery, J. P.; Greiner, J.; Hasegawa, S.; Hora, J. L.; Knust, F.; Kuroda, D.; Osip, D.; Rau, A.; Rivkin, A.; Schady, P.; Thomas-Osip, J.; Trilling, D.; Urakawa, S.; Vilenius, E.; Weissman, P.; Zeidler, P.

    2017-03-01

    The JAXA Hayabusa-2 mission was approved in 2010 and launched on December 3, 2014. The spacecraft will arrive at the near-Earth asteroid 162173 Ryugu (1999 JU3) in 2018 where it will perform a survey, land and obtainsurface material, then depart in December 2019 and return to Earth in December 2020. We observed Ryugu with the Herschel Space Observatory in April 2012 at far-infrared thermal wavelengths, supported by several ground-based observations to obtain optical lightcurves. We reanalysed previously published Subaru-COMICS and AKARI-IRC observations and merged them with a Spitzer-IRS data set. In addition, we used a large set of Spitzer-IRAC observations obtained in the period January to May, 2013. The data set includes two complete rotational lightcurves and a series of ten "point-and-shoot" observations, all at 3.6 and 4.5 μm. The almost spherical shape of the target together with the insufficient lightcurve quality forced us to combine radiometric and lightcurve inversion techniques in different ways to find the object's spin-axis orientation, its shape and to improve the quality of the key physical and thermal parameters. Handling thermal data in inversion techniques remains challenging: thermal inertia, roughness or local structures influence the temperature distribution on the surface. The constraints for size, spin or thermal properties therefore heavily depend on the wavelengths of the observations. We find that the solution which best matches our data sets leads to this C class asteroid having a retrograde rotation with a spin-axis orientation of (λ = 310°-340°; β = -40° ± 15°) in ecliptic coordinates, an effective diameter (of an equal-volume sphere) of 850 to 880 m, a geometric albedo of 0.044 to 0.050 and a thermal inertia in the range 150 to 300 J m-2 s-0.5 K-1. Based on estimated thermal conductivities of the top-layer surface in the range 0.1 to 0.6 W K-1 m-1, we calculated that the grain sizes are approximately equal to between 1 and 10

  11. Nuclear spin orientation of {sup 12,13}B created in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nagatomo, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Matsuta, K. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Akutsu, K. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Iwakoshi, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nakashima, Y. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Sumikama, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Ogura, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Mihara, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Fujiwara, H. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Kumashiro, S. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Minamisono, K. [TRIUMF, Vancouver, B.C., V6T 2A3 (Canada); Minamisono, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Fukuda, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Miyake, M. [Cyclotron RI Center, Tohoku University, Sendai, Miyagi 980-8578 (Japan); Momota, S. [Kochi University of Technology, Tosayamada, Kochi 782-8502 (Japan); Nojiri, Y. [Kochi University of Technology, Tosayamada, Kochi 782-8502 (Japan); Kitagawa, A. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan); Sasaki, M. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan); Torikoshi, M. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan); Kanazawa, M. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan); Suda, M. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan); Sato, S. [National Institute of Radiological Sciences, Inage, Chiba 263-0024 (Japan)] [and others

    2004-12-27

    The momentum dependences of the nuclear spin polarization P and alignment A of {sup 12}B (I{sup {pi}} = 1{sup +}, T{sub 1/2} = 20.20 ms) [{sup 13}B (I{sup {pi}} = 3/2{sup -}, T{sub 1/2} = 17.36 ms)] produced in 100AMeV {sup 13}C [{sup 15}N] + Be collisions have been measured by detecting the {beta}-ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some depolarization mechanisms must be taken into account related with the collision process itself. Comparing the signs of the observed alignment of {sup 12}B and {sup 13}B, the sign of the quadrupole moment Q({sup 13}B) was determined to be positive.

  12. Systematic study of surface morphology, photoluminescence efficiency, and spin-detection sensitivity in (110)-oriented GaAs/AlGaAs quantum wells

    Science.gov (United States)

    Iba, Satoshi; Saito, Hidekazu; Watanabe, Ken; Ohno, Yuzo; Yuasa, Shinji

    2016-11-01

    We prepared (110)-oriented GaAs/AlGaAs multiple-quantum-well (MQW) samples by molecular beam epitaxy (MBE) under different growth conditions, and conducted systematic measurements of surface morphology, photoluminescence (PL), and spin-detection sensitivity at room temperature. Excellent surface flatness and high PL intensity were observed for the samples grown at temperatures ≥450 °C and As4/Ga flux ratios ≥40. It was found that the PL intensity of (110) MQWs was higher than that of the conventional (100) MQWs grown using the same MBE system. At the same time, we confirmed that the spin-detection sensitivity of (110) MQWs we obtained was an order of magnitude higher than that of the (100) MQWs. These results suggest that the newly developed (110) MQWs indeed have greater advantages than the conventional (100) MQWs for use in emerging spin-optical devices such as spin-controlled lasers.

  13. Technological advances in transurethral resection of the prostate: bipolar versus monopolar TURP.

    Science.gov (United States)

    Issa, Muta M

    2008-08-01

    One of the most significant recent advancements in transurethral resection of the prostate (TURP) is the incorporation of bipolar technology. Bipolar circuitry allows TURP to be performed in a normal saline environment, which addresses a fundamental concern of conventional monopolar TURP (i.e., the use of hypo-osmolar irrigation). As a result, the risks of dilutional hyponatremia and transurethral resection (TUR) syndrome are eliminated, allowing for longer and safer resection. This review discusses the principles and applications of electrosurgery in conventional monopolar as well as new bipolar saline-based TURP systems. This review also addresses the positive impact on patient safety and resident training.

  14. Angular momentum dynamics and the intrinsic drift of monopolar vortices on a rotating sphere

    NARCIS (Netherlands)

    Van der Toorn, R.; Zimmerman, J.T.F.

    2010-01-01

    On the basis of the angular momentum equation for a fluid shell on a rotating planet, we analyze the intrinsic drift of a monopolar vortex in the shell. Central is the development of a general angular momentum equation for Eulerian fluid mechanics based on coordinate-free, general tensorial

  15. Angular momentum dynamics and the intrinsic drift of monopolar vortices on a rotating sphere

    NARCIS (Netherlands)

    Van der Toorn, R.; Zimmerman, J.T.F.

    2010-01-01

    On the basis of the angular momentum equation for a fluid shell on a rotating planet, we analyze the intrinsic drift of a monopolar vortex in the shell. Central is the development of a general angular momentum equation for Eulerian fluid mechanics based on coordinate-free, general tensorial represen

  16. Behavioral pattern of a monopolar passive direct methanol fuel cell stack

    Science.gov (United States)

    Kim, Young-Jin; Bae, Byungchan; Scibioh, M. Aulice; Cho, EunAe; Ha, Heung Yong

    A passive, air-breathing, monopolar, liquid feed direct methanol fuel cell (DMFC) stack consisting of six unit cells with no external pump, fan or auxiliary devices to feed the reactants has been designed and fabricated for its possible employment as a portable power source. The configurations of the stack of monopolar passive feed DMFCs are different from those of bipolar active feed DMFCs and therefore its operational characteristics completely vary from the active ones. Our present investigation primarily focuses on understanding the unique behavioral patterns of monopolar stack under the influence of certain operating conditions, such as temperature, methanol concentration and reactants feeding methods. With passive reactants supply, the temperature of the stack and open circuit voltage (OCV) undergo changes over time due to a decrease in concentration of methanol in the reservoir as the reaction proceeds. Variations in performance and temperature of the stack are mainly influenced by the concentration of methanol. Continuous operation of the passive stack is influenced by the supply of methanol rather than air supply or water accumulation at the cathode. The monopolar stack made up of six unit cells exhibits a total power of 1000 mW (37 mW cm -2) with 4 M methanol under ambient conditions.

  17. Comparison between bipolar pulsed radiofrequency and monopolar pulsed radiofrequency in chronic lumbosacral radicular pain

    Science.gov (United States)

    Chang, Min Cheol; Cho, Yun Woo; Ahn, Sang Ho

    2017-01-01

    Abstract Background: Chronic lumbosacral radicular pain is a challenging medical problem with respect to therapeutic management. Many patients with lumbosacral radicular pain complain of persistent leg pain after transforaminal epidural steroid injection. Nowadays, pulsed radiofrequency (PRF) stimulation on the dorsal root ganglion (DRG) is widely used for controlling lumbosacral radicular pain. Methods: We evaluated the effect of bipolar PRF on the DRG for the management of lumbosacral radicular pain. In addition, we compared the effect of bipolar PRF to monopolar PRF. Fifty patients with chronic lumbosacral radicular pain were included in the study and randomly assigned to 1 of 2 groups, the bipolar or monopolar PRF group (n = 25 per group). Pain intensity was evaluated using a numeric rating scale (NRS) at pretreatment, and 1, 2, and 3 months after treatment. Results: When compared to the pretreatment NRS scores, patients in both groups showed a significant decrease in NRS scores at 1, 2, and 3 months after treatment. Reductions in the NRS scores over time were significantly larger in the bipolar PRF group. Three months after treatment, 19 patients (76.0%) in the bipolar PRF group and 12 patients (48.0%) in the monopolar PRF group reported successful pain relief (pain relief of ≥50%). Conclusion: The use of bipolar PRF on the DRG can be an effective and safe interventional technique for chronic refractory lumbosacral radiculopathy, particularly in patients whose pain are refractory to epidural steroid injection or monopolar PRF stimulation. PMID:28248888

  18. Comparison of the Outcomes of Monopolar and Bipolar Radiofrequency Ablation in Surgical Treatment of Atrial Fibrillation

    Institute of Scientific and Technical Information of China (English)

    Wei-zhao Huang; Ying-meng Wu; Hong-yu Ye; Hai-ming Jiang

    2014-01-01

    Objective To compare the therapeutic effects and safety of monopolar and bipolar radiofrequency (RF) ablation used during cardiac surgery to treat atrial fibrillation. Methods We retrospectively studied a total of 81 patients with chronic atrial fibrillation who underwent open cardiac surgery with concomitant RF ablation between January 2007 and March 2011. Fifty-eight patients received bipolar RF ablation and 23 received monopolar RF ablation, respectively. The sinus rhythm restoration rate, the procedural duration, the frequency of severe perioperative complications, and mortality were compared between the two groups. Results The sinus rhythm restoration rate did not differ significantly between the two groups after follow-up of 15.1 ± 12.6 months (P=0.199). The frequencies of severe perioperative complications and mortality were also similar in the two groups. The total procedural time using bipolar RF ablation was significantly shorter than that using monopolar ablation (19.7±4.6 minutes vs. 28.1±8.5 minutes, P Conclusions Both monopolar and bipolar RF ablation are safe and effective in treating chronic atrial fibrillation patients during open cardiac surgery, but bipolar RF ablation is more convenient in practice.

  19. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair

    Science.gov (United States)

    Chang, Zhiwei; Halle, Bertil

    2013-10-01

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

  20. MONOPOLAR ELECTROCAUTERY VS SURGICAL CLIPS IN CONTROL OF CYSTIC ARTERY IN LAPAROSCOPIC CHOLECYSTECTOMY: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Ridipta Sekha

    2016-04-01

    Full Text Available BACKGROUND Laparoscopic cholecystectomy has been extensively accepted since Mouret first successfully introduced the procedure in 1987. During this procedure the cystic artery can be controlled using surgical clips, harmonic scalpel and ligature or monopolar cautery. The extensive use of surgical clips in laparoscopic surgery has led to a variety of complications. Monopolar electrocoagulation can be used to control the cystic artery as it is cheap and universally available. Hence in this study, we compared monopolar electrocautery with clip application for securing haemostasis and to identify the safest and least complicated way for haemostasis of the cystic artery in laparoscopic cholecystectomy. METHODS A retrospective analysis of 201 patients were done who were planned for laparoscopic cholecystectomy. Among them 3 were converted to open cholecystectomy due to intraoperative bleeding. The rest 198 patients underwent successful laparoscopic cholecystectomy. In 42 patients the cystic artery was ligated using Ligaclip 300, while in 156 patients the artery was coagulated using monopolar cautery with hook. The patients were observed for any incidences of post-operative haemorrhage and bile leak, difference in length of hospital stay and post-operative complications. RESULTS The mean age was 40.26 years with M:F ratio 1:4. About 86% (135 and 88% (37 patients, respectively in electrocautery and Ligaclip group were discharged on the first post-operative day itself. Only 3 (1.5% patients, 2 in electrocautery and 1 in Ligaclip group developed post-operative port site infection. These differences were not statistically significant. CONCLUSION We conclude that monopolar electrocautery can be used as a safer alternative to surgical clips in control of cystic artery, especially in developing countries.

  1. Determination of Spin Axis Orientation of Geosynchronous Objects Using Space-Based Sensors: An Initial Feasibility Investigation

    Science.gov (United States)

    2010-09-01

    The spin axis of a rotating satellite can be determined by studying the rate of change of the observed spin rate as a function of the satellite’s...position in its orbit. The observed spin rate change is largest when the rate of change of the sun-satellite-observer angle is largest. Application of...this method is problematic for deep-space objects due to the slow rate of change of this angle, however some assumptions can be made to make the problem

  2. Interaction of monopolar and dipolar vortices with a shear flow: a numerical study

    Science.gov (United States)

    Kamp, Leon; Marques Rosas Fernandes, Vitor; van Heijst, Gert-Jan; Clercx, Herman

    2014-11-01

    Interaction of large-scale flows with vortices is of fundamental and widespread importance in geophysical fluid dynamics and also, more recently for the dynamics of fusion plasma. More specifically the interplay between two-dimensional turbulence constituted by a collection of unsteady eddies and so-called zonal flows has gained considerable interest because of the relevance for transport and associated barriers. We present numerical results on the interaction of individual monopolar and dipolar vortices with typical sheared channel flows (Couette and Poiseuille). Contrary to monopolar vortices, dipolar ones tend to retain their compactness while propagating through the shear flow along curved pathways without much distortion. Simulations on the interaction of a driven turbulent field with mentioned channel flows are used to explore the suppression of turbulence and turbulent transport and the pronounced role played by the boundaries on these.

  3. Surgical complications specific to monopolar electrosurgical energy: engineering changes that have made electrosurgery safer.

    Science.gov (United States)

    Odell, Roger C

    2013-01-01

    Monopolar electrosurgical energy is the most commonly used energy source during laparotomic and laparoscopic surgery. The clinical application of monopolar energy is not without risk. Monopolar electrosurgical energy was introduced into surgical practice at the turn of the 20th century. Alternate site burns during laparotomic application were the most common complication for the first half century (i.e., ground point burns and dispersive electrode burns [1920-1970]). The aims of this article were to discuss historic design flaws associated with the most common alternate site burns, ground point burns, and dispersive electrode burns and the technological advancements introduced to mitigate these risks to the patient and to discuss current design flaws associated with stray energy burns during laparoscopy because of insulation failure and capacitive coupling and the technological advancements introduced to eliminate these risks to the patient. Today, insulation failure and capacitive coupling are the most common reasons for electrosurgical injury during laparocopic procedures. There is a need for advanced technology such as active electrode monitoring to address these invisible risks to the surgeon and their patients. In addition, the laparoscopic surgeon should be encouraged to study the basic biophysics involved in electrosurgery.

  4. [Bipolar versus monopolar transurethral resection of the prostate: a prospective randomized study].

    Science.gov (United States)

    Ghozzi, S; Ghorbel, J; Ben Ali, M; Dridi, M; Maarouf, J; Khiari, R; Ben Rais, N

    2014-02-01

    To compare bipolar with standard monopolar transurethral resection of the prostate (TURP). A prospectively randomized study was conducted between January 2010 and September 2011. Primary end points studied were efficacy (maximum flow rate [Qmax], International Prostate Symptom Score) and safety (adverse events, decline in postoperative serum sodium [Na+] and haemoglobin [Hb] levels). Secondary end points were operation time and duration of irrigation, catheterization, and hospitalization. Sixty consecutive patients were randomized and completed the study, with 29 patients in the monopolar TURP group and 31 in the TURIS group. At baseline, the two groups were comparable in age, prostate volume, mean prostate-specific antigen value, International Prostate Symptom Score, and they had at least 12 months of follow-up. Declines in the mean postoperative serum Na+ for bipolar and monopolar TURP groups were 1.2 and 8.7 mmol/L, respectively. However, there was no statistical difference in the decline in postoperative Hb between the two groups. The mean catheterization time was 26.6 and 52 hours in the bipolar and standard groups, respectively. This difference was statistically significant as was the difference in the time to hospital discharge. The IPSS and Qmax improvements were comparable between the two groups at 12 months of follow-up. No clinically relevant differences in short-term efficacy are existed between the two techniques, but bipolar TURP is preferable due to a more favorable safety profile and shorter catheterization duration. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  5. Monopolin subunit Csm1 associates with MIND complex to establish monopolar attachment of sister kinetochores at meiosis I.

    Science.gov (United States)

    Sarkar, Sourav; Shenoy, Rajesh T; Dalgaard, Jacob Z; Newnham, Louise; Hoffmann, Eva; Millar, Jonathan B A; Arumugam, Prakash

    2013-01-01

    Sexually reproducing organisms halve their cellular ploidy during gametogenesis by undergoing a specialized form of cell division known as meiosis. During meiosis, a single round of DNA replication is followed by two rounds of nuclear divisions (referred to as meiosis I and II). While sister kinetochores bind to microtubules emanating from opposite spindle poles during mitosis, they bind to microtubules originating from the same spindle pole during meiosis I. This phenomenon is referred to as mono-orientation and is essential for setting up the reductional mode of chromosome segregation during meiosis I. In budding yeast, mono-orientation depends on a four component protein complex referred to as monopolin which consists of two nucleolar proteins Csm1 and Lrs4, meiosis-specific protein Mam1 of unknown function and casein kinase Hrr25. Monopolin complex binds to kinetochores during meiosis I and prevents bipolar attachments. Although monopolin associates with kinetochores during meiosis I, its binding site(s) on the kinetochore is not known and its mechanism of action has not been established. By carrying out an imaging-based screen we have found that the MIND complex, a component of the central kinetochore, is required for monopolin association with kinetochores during meiosis. Furthermore, we demonstrate that interaction of monopolin subunit Csm1 with the N-terminal domain of MIND complex subunit Dsn1, is essential for both the association of monopolin with kinetochores and for monopolar attachment of sister kinetochores during meiosis I. As such this provides the first functional evidence for a monopolin-binding site at the kinetochore.

  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. Quasi-monopolar stimulation: a novel electrode design configuration for performance optimization of a retinal neuroprosthesis.

    Directory of Open Access Journals (Sweden)

    Gita Khalili Moghadam

    Full Text Available In retinal neuroprostheses, spatial interaction between electric fields from various electrodes - electric crosstalk - may occur in multielectrode arrays during simultaneous stimulation of the retina. Depending on the electrode design and placement, this crosstalk can either enhance or degrade the functional characteristics of a visual prosthesis. To optimize the device performance, a balance must be satisfied between the constructive interference of crosstalk on dynamic range and power consumption and its negative effect on artificial visual acuity. In the present computational modeling study, we have examined the trade-off in these positive and negative effects using a range of currently available electrode array configurations, compared to a recently proposed stimulation strategy - the quasi monopolar (QMP configuration - in which the return current is shared between local bipolar guards and a distant monopolar electrode. We evaluate the performance of the QMP configuration with respect to the implantation site and electrode geometry parameters. Our simulation results demonstrate that the beneficial effects of QMP are only significant at electrode-to-cell distances greater than the electrode dimensions. Possessing a relatively lower activation threshold, QMP was found to be superior to the bipolar configuration in terms of providing a relatively higher visual acuity. However, the threshold for QMP was more sensitive to the topological location of the electrode in the array, which may need to be considered when programming the manner in which electrode are simultaneously activated. This drawback can be offset with a wider dynamic range and lower power consumption of QMP. Furthermore, the ratio of monopolar return current to total return can be used to adjust the functional performance of QMP for a given implantation site and electrode parameters. We conclude that the QMP configuration can be used to improve visual information

  8. Enhanced inverse spin-Hall voltage in (001) oriented Fe4N/Pt polycrystalline films without contribution of planar-Hall effect

    Science.gov (United States)

    Isogami, Shinji; Tsunoda, Masakiyo

    2016-04-01

    In this study, the output DC electric voltage (V out) generated by a Pt-capped Fe4N bilayer film (Fe4N/Pt) under ferromagnetic resonance conditions at room temperature was assessed. The contributions from the inverse spin-Hall effect (ISHE), the planar-Hall effect (PHE) and the anomalous-Hall effect (AHE) were separated from the output voltage by analysis of V out values determined at varying external field polar angles. The results showed that the polarity of the ISHE (V ISHE) component of V out was opposite to that of the PHE (V PHE). As a result, the magnitude of the intrinsic V ISHE was beyond V out by as much as the magnitude of V PHE. The X-ray diffraction structural analysis revealed the polycrystal of the Fe4N/Pt with (001) orientation, which might be one of the possible mechanisms for enhanced intrinsic V ISHE.

  9. Electric field control of spin re-orientation in perpendicular magnetic tunnel junctions—CoFeB and MgO thickness dependence

    Science.gov (United States)

    Meng, Hao; Naik, Vinayak Bharat; Liu, Ruisheng; Han, Guchang

    2014-07-01

    We report an investigation of electric-field (EF) control of spin re-orientation as functions of the thicknesses of CoFeB free layer (FL) and MgO layer in synthetic-antiferromagnetic pinned magnetic tunnel junctions with perpendicular magnetic anisotropy. It is found that the EF modulates the coercivity (Hc) of the FL almost linearly for all FL thicknesses, while the EF efficiency, i.e., the slope of the linearity, increases as the FL thickness increases. This linear variation in Hc is also observed for larger MgO thicknesses (≥1.5 nm), while the EF efficiency increases only slightly from 370 to 410 Oe nm/V when MgO thickness increases from 1.5 to 1.76 nm. We have further observed the absence of quasi-DC unipolar switching. We discuss its origin and highlight the underlying challenges to implement the EF controlled switching in a practical magnetic memory.

  10. Electron transfer flavoprotein domain II orientation monitored using double electron-electron resonance between an enzymatically reduced, native FAD cofactor, and spin labels.

    Science.gov (United States)

    Swanson, Michael A; Kathirvelu, Velavan; Majtan, Tomas; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

    2011-03-01

    Human electron transfer flavoprotein (ETF) is a soluble mitochondrial heterodimeric flavoprotein that links fatty acid β-oxidation to the main respiratory chain. The crystal structure of human ETF bound to medium chain acyl-CoA dehydrogenase indicates that the flavin adenine dinucleotide (FAD) domain (αII) is mobile, which permits more rapid electron transfer with donors and acceptors by providing closer access to the flavin and allows ETF to accept electrons from at least 10 different flavoprotein dehydrogenases. Sequence homology is high and low-angle X-ray scattering is identical for Paracoccus denitrificans (P. denitrificans) and human ETF. To characterize the orientations of the αII domain of P. denitrificans ETF, distances between enzymatically reduced FAD and spin labels in the three structural domains were measured by double electron-electron resonance (DEER) at X- and Q-bands. An FAD to spin label distance of 2.8 ± 0.15 nm for the label in the FAD-containing αII domain (A210C) agreed with estimates from the crystal structure (3.0 nm), molecular dynamics simulations (2.7 nm), and rotamer library analysis (2.8 nm). Distances between the reduced FAD and labels in αI (A43C) were between 4.0 and 4.5 ± 0.35 nm and for βIII (A111C) the distance was 4.3 ± 0.15 nm. These values were intermediate between estimates from the crystal structure of P. denitrificans ETF and a homology model based on substrate-bound human ETF. These distances suggest that the αII domain adopts orientations in solution that are intermediate between those which are observed in the crystal structures of free ETF (closed) and ETF bound to a dehydrogenase (open).

  11. Velocity-tunable slow beams of cold O2 in a single spin-rovibronic state with full angular-momentum orientation by multistage Zeeman deceleration

    Science.gov (United States)

    Wiederkehr, A. W.; Schmutz, H.; Motsch, M.; Merkt, F.

    2012-08-01

    Cold samples of oxygen molecules in supersonic beams have been decelerated from initial velocities of 390 and 450 m s-1 to final velocities in the range between 150 and 280 m s-1 using a 90-stage Zeeman decelerator. (2 + 1) resonance-enhanced-multiphoton-ionization (REMPI) spectra of the 3sσ g 3Π g (C) ? two-photon transition of O2 have been recorded to characterize the state selectivity of the deceleration process. The decelerated molecular sample was found to consist exclusively of molecules in the J ‧‧ = 2 spin-rotational component of the X ? ground state of O2. Measurements of the REMPI spectra using linearly polarized laser radiation with polarization vector parallel to the decelerator axis, and thus to the magnetic-field vector of the deceleration solenoids, further showed that only the ? magnetic sublevel of the N‧‧ = 1, J ‧‧ = 2 spin-rotational level is populated in the decelerated sample, which therefore is characterized by a fully oriented total-angular-momentum vector. By maintaining a weak quantization magnetic field beyond the decelerator, the polarization of the sample could be maintained over the 5 cm distance separating the last deceleration solenoid and the detection region.

  12. Thermal and histological effects of bipolar and monopolar electrosurgical resection of the prostate in a canine model

    Science.gov (United States)

    Ko, Raymond; Chew, Ben H.; Tan, Andrew H. H.; Rowe, Elaine; Razvi, Hassan

    2007-02-01

    Bipolar transurethral resection (TUR) is an alternative to monopolar TUR in the treatment of benign prostatic hyperplasia and offers the major advantage of utilizing 0.9% sodium chloride for irrigation. Claims have been made that bipolar electrosurgery in clinical use causes less thermal damage to adjacent tissues. We sought to assess tissue thermometry and histopathologic thermal effects of a bipolar system in comparison to standard monopolar TUR in an animal model. Eight male beagles were studied. A lower midline incision was used to access the prostate. Fiber-optic thermosensors were placed within the prostate. A midline cystotomy was used to perform antegrade resection of the prostate using a bipolar TUR system (VISTA CTR) with normal saline or a monopolar device using glycine. Resection of a 1cm cavity was performed in each lateral lobe. Animals were sacrificed acutely and the prostates excised for histopathological assessment of thermal damage. In both groups, prostatic temperature rises were transient and fell with increasing distance from the resection site. The greatest temperature increase occurred in the monopolar group (24.2 +/- 3.9°C) compared to the bipolar group (6.8 +/- 1.8°C, p<0.0001). The depth of thermal damage was greatest in the monopolar group (0.59 +/- 0.27mm vs 0.15 +/-0.02mm in the bipolar arm, p<0.0001). Bipolar TUR generated significantly less heat and produced less histopathological thermal damage compared to monopolar prostatic resection in a canine model. The clinical benefits of these findings remain to be determined.

  13. Black hole-neutron star mergers at realistic mass ratios: Equation of state and spin orientation effects

    CERN Document Server

    Foucart, Francois; Duez, Matthew D; Kidder, Lawrence E; MacDonald, Ilana; Ott, Christian D; Pfeiffer, Harald P; Scheel, Mark A; Szilagyi, Bela; Teukolsky, Saul A

    2012-01-01

    Black hole-neutron star mergers resulting in the disruption of the neutron star and the formation of an accretion disk and/or the ejection of unbound material are prime candidates for the joint detection of gravitational-wave and electromagnetic signals when the next generation of gravitational-wave detectors comes online. However, the disruption of the neutron star and the properties of the post-merger remnant are very sensitive to the parameters of the binary. In this paper, we study the impact of the radius of the neutron star and the alignment of the black hole spin for systems within the range of mass ratio currently deemed most likely for field binaries (M_BH ~ 7 M_NS) and for black hole spins large enough for the neutron star to disrupt (J/M^2=0.9). We find that: (i) In this regime, the merger is particularly sensitive to the radius of the neutron star, with remnant masses varying from 0.3M_NS to 0.1M_NS for changes of only 2 km in the NS radius; (ii) 0.01-0.05M_sun of unbound material can be ejected w...

  14. Reducing Postoperative Pain from Tonsillectomy Using Monopolar Electrocautery by Cooling the Oropharynx

    Science.gov (United States)

    Vieira, Lucas; Nissen, Leonardo; Sela, Gustavo; Amara, Yara; Fonseca, Vinicius

    2014-01-01

    Objective Evaluate intraoperative cooling of the oropharynx to reduce postoperative pain in tonsillectomy using monopolar electrocautery. Methods Sixty-six patients, age 1 to 12 years, were selected for the study, 33 in the control group and 33 in the experimental group. After randomization, patients underwent subcapsular dissection and hemostasis with monopolar electrocautery. Patients in the experimental group had the oropharynx cooled after tonsil dissection and hemostasis for 10 minutes. The procedure was done through the oral cavity by irrigation with 500 mL of 0.9% saline, in temperatures between 5°C and 10°C, for 5 minutes. The evaluation of postoperative pain was made with the pain visual analog scale (VAS) for 10 days. As complementary data on the evaluation of pain, we recorded daily use of ketoprofen for pain relief. Results Pain after tonsillectomy assessed by VAS was significantly lower in the experimental group at days 0, 5, and 6 (p < 0.05). There were no differences in the use of ketoprofen between the groups. Conclusion Cooling of the oropharynx after tonsillectomy promotes clinically significant reduction in postoperative pain, without additional complications. PMID:25992083

  15. Reducing Postoperative Pain from Tonsillectomy Using Monopolar Electrocautery by Cooling the Oropharynx

    Directory of Open Access Journals (Sweden)

    Vieira, Lucas

    2014-01-01

    Full Text Available Objective Evaluate intraoperative cooling of the oropharynx to reduce postoperative pain in tonsillectomy using monopolar electrocautery. Methods Sixty-six patients, age 1 to 12 years, were selected for the study, 33 in the control group and 33 in the experimental group. After randomization, patients underwent subcapsular dissection and hemostasis with monopolar electrocautery. Patients in the experimental group had the oropharynx cooled after tonsil dissection and hemostasis for 10 minutes. The procedure was done through the oral cavity by irrigation with 500 mL of 0.9% saline, in temperatures between 5°C and 10°C, for 5 minutes. The evaluation of postoperative pain was made with the pain visual analog scale (VAS for 10 days. As complementary data on the evaluation of pain, we recorded daily use of ketoprofen for pain relief. Results Pain after tonsillectomy assessed by VAS was significantly lower in the experimental group at days 0, 5, and 6 (p < 0.05. There were no differences in the use of ketoprofen between the groups. Conclusion Cooling of the oropharynx after tonsillectomy promotes clinically significant reduction in postoperative pain, without additional complications.

  16. Ultrasonic energy device versus monopolar energy device in laparoscopic transabdominal preperitoneal (TAPP) inguinal hernia repair.

    Science.gov (United States)

    Otsuka, Shimpei; Kaneoka, Yuji; Maeda, Atsuyuki; Takayama, Yuichi; Fukami, Yasuyuki; Onoe, Shunsuke

    2017-03-01

    Laparoscopic transabdominal preperitoneal (TAPP) is gaining popularity as an approach to repairing of inguinal hernia. In many institutions, a disposable ultrasonic energy device is used in the TAPP repair procedure. However, the benefit and necessity of an ultrasonic device are unclear. We have switched to use of a reusable monopolar energy device, and we conducted a retrospective study comparing the surgical results obtained with each of the energy devices. Our study group comprised 241 adults who underwent TAPP repair for inguinal hernia between November 2012 and December 2014. We compared clinical characteristics, and surgical outcomes between patients in whom a disposable ultrasonic energy device was used (n = 116, U group) and those in whom a reusable monopolar energy device (n = 125, M group) was used. There was no statistically significant difference between the 2 groups in age, sex, body mass index, or hernia type. In cases of unilateral hernia, operation time was significantly longer in the U group than in the M group (71.4 vs. 59.4 min, respectively, p energy device lead us to conclude that the ultrasonic energy device is unnecessary for simple TAPP repair.

  17. Nuclear Spin Orientation Created in Heavy Ion Collisions and the Sign of the Q Moment of {sup 13}B

    Energy Technology Data Exchange (ETDEWEB)

    Nagatomo, T., E-mail: nagatomo@vg.phys.sci.osaka-u.ac.jp; Matsuta, K.; Nakashima, Y. [Osaka University, Department of Physics (Japan); Sumikama, T. [RIKEN (Japan); Ogura, M.; Akutsu, K.; Iwakoshi, T.; Fujiwara, H.; Minamisono, T.; Fukuda, M.; Mihara, M.; Miyake, T. [Osaka University, Department of Physics (Japan); Minamisono, K. [TRIUMF (Canada); Momota, S.; Nojiri, Y. [Kochi University of Technology (Japan); Kitagawa, A. [National Institute of Radiological Sciences (Japan); Sasaki, M. [Ritsumeikan University, Department of Photonics (Japan); Torikoshi, M.; Kanazawa, M.; Suda, M. [National Institute of Radiological Sciences (Japan)

    2004-12-15

    The momentum dependences of the nuclear spin polarization P and alignment A of {sup 13}B(I{sup {pi}=}3/2{sup +}, T{sub 1/2} = 17.36 ms) produced in the 100A MeV {sup 15}N + Be collisions have been measured by detecting {beta}-ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some relaxation mechanisms must be take into account. Comparing the signs of the observed alignment of {sup 12}B, the sign of the quadrupole coupling constant eqQ of {sup 13}B in TiO{sub 2} was determined to be positive.

  18. Monopolar radiofrequency ablation using a dual-switching system and a separable clustered electrode: Evaluation of the in vivo efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jeong Hee; Lee, Jeong Min; Hwang, Eui Jin; Hwang, In Pyung; Beak, Jee Hyun; Han, Joon Koo; Choi, Byung Ihn [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2014-04-15

    To determine the in vivo efficiency of monopolar radiofrequency ablation (RFA) using a dual-switching (DS) system and a separable clustered (SC) electrode to create coagulation in swine liver. Thirty-three ablation zones were created in nine pigs using a DS system and an SC electrode in the switching monopolar mode. The pigs were divided into two groups for two experiments: 1) preliminary experiments (n = 3) to identify the optimal inter-electrode distances (IEDs) for dual-switching monopolar (DSM)-RFA, and 2) main experiments (n = 6) to compare the in vivo efficiency of DSM-RFA with that of a single-switching monopolar (SSM)-RFA. RF energy was alternatively applied to one of the three electrodes (SSM-RFA) or concurrently applied to a pair of electrodes (DSM-RFA) for 12 minutes in in vivo porcine livers. The delivered RFA energy and the shapes and dimensions of the coagulation areas were compared between the two groups. No pig died during RFA. The ideal IEDs for creating round or oval coagulation area using the DSM-RFA were 2.0 and 2.5 cm. DSM-RFA allowed more efficient RF energy delivery than SSM-RFA at the given time (23.0 ± 4.0 kcal vs. 16.92 ± 2.0 kcal, respectively; p 0.0005). DSM-RFA created a significantly larger coagulation volume than SSM-RFA (40.4 ± 16.4 cm{sup 3} vs. 20.8 ± 10.7 cm{sup 3}; p < 0.001). Both groups showed similar circularity of the ablation zones (p = 0.29). Dual-switching monopolar-radiofrequency ablation using an SC electrode is feasible and can create larger ablation zones than SSM-RFA as it allows more RF energy delivery at a given time.

  19. Ultrasonically activated scalpel versus monopolar electrocautery shovel in laparoscopic total mesorectal excision for rectal cancer

    Institute of Scientific and Technical Information of China (English)

    Bao-Jun Zhou; Wei-Qing Song; Qing-Hui Yan; Jian-Hui Cai; Feng-An Wang; Jin Liu; Guo-Jian Zhang; Guo-Qiang Duan; Zhan-Xue Zhang

    2008-01-01

    AIM: To investigate the feasibility and safety of monopolar electrocautery shovel (ES) in laparoscopic total mesorectal excision (TME) with anal sphincter preservation for rectal cancer in order to reduce the cost of the laparoscopic operation, and to compare ES with the ultrasonically activated scalpel (US).METHODS: Forty patients with rectal cancer, who underwent laparoscopic TME with anal sphincter preservation from June 2005 to June 2007, were randomly divided into ultrasonic scalpel group and monopolar ES group, prospectively. White blood cells (WBC) were measured before and after operation, operative time, blood loss, pelvic volume of drainage, time of anal exhaust, visual analogue scales (VAS) and surgery-related complications were recorded.RESULTS: All the operations were successful; no one was converted to open procedure. No significant differences were observed in terms of preoperative and postoperative d1 and d3 WBC counts (P=0.493, P=0.375, P=0.559), operation time (P=0.235), blood loss (P=0.296), anal exhaust time (P=0.431), pelvic drainage volume and VAS in postoperative d1 (P=0.431, P=0.426) and d3 (P=0.844, P=0.617) between ES group and US group. The occurrence of surgery-related complications such as anastomotic leakage and woundinfection was the same in the two groups.CONCLUSION: ES is a safe and feasible tool as same as US used in laparoscopic TME with anal sphincter preservation for rectal cancer on the basis of the skillful laparoscopic technique and the complete understanding of laparoscopic pelvic anatomy. Application of ES can not only reduce the operation costs but also benefit the popularization of laparoscopic operation for rectal cancer patients.

  20. Method of destruction of the pathological excitation sources in the heart by original monopolar electrode

    Directory of Open Access Journals (Sweden)

    M. M. Sychyk

    2016-06-01

    Full Text Available Purpose. This work is devoted to the study of destruction of the pathological excitation sources in the heart by the original monopolar electrode and the high-frequency electrosurgical generator Erbe VIO-100 S (Germany in the coagulation mode in order to optimize technology of their using in surgical practice for Maze surgery. Methodology. Experimental study of the effect of electric current on the myocardium were performed in the laboratory on the endocardial part of four remote pig hearts in the cold hibernation state. Temperature evaluation of myocardial contact with the electrode was carried out using mathematical modeling of temperature fields of radio frequency current interaction with the tissue in the program Comsol Multiphysics. Results. Safe and effective destruction size, nature of histological and temperature changes in the interaction region of myocardial tissue with a source of electrical current depending on the duration and power application to stop the spread of pathological excitation sources in the heart were defined. Originality. The recommendations on the choice of the optimal parameters for the application of the generator Erbe and the original monopolar electrode were developed and adapted to radiofrequency ablation of myocardial tissue in the open heart for the arrhythmias treatment in order to reduce the total duration of surgery with cardiopulmonary bypass. Practical value. The results have been introduced in surgical practice of the State Institution «M. M. Amosov National Institute of Cardiovascular Surgery Ukraine NAMS of Ukraine». The work has great practical importance, because the expanding of the functional range of generator Erbe VIO-100 S (Germany applications and reducing of the cost of radio frequency ablation procedure in comparison with the use of specialized disposable bipolar electrodes.

  1. Electric field control of spin re-orientation in perpendicular magnetic tunnel junctions—CoFeB and MgO thickness dependence

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Hao; Naik, Vinayak Bharat; Liu, Ruisheng; Han, Guchang, E-mail: han-guchang@dsi.a-star.edu.sg [Data Storage Institute, A*STAR (Agency for Science Technology and Research), 5 Engineering Drive 1, DSI Building, Singapore 117608 (Singapore)

    2014-07-28

    We report an investigation of electric-field (EF) control of spin re-orientation as functions of the thicknesses of CoFeB free layer (FL) and MgO layer in synthetic-antiferromagnetic pinned magnetic tunnel junctions with perpendicular magnetic anisotropy. It is found that the EF modulates the coercivity (Hc) of the FL almost linearly for all FL thicknesses, while the EF efficiency, i.e., the slope of the linearity, increases as the FL thickness increases. This linear variation in Hc is also observed for larger MgO thicknesses (≥1.5 nm), while the EF efficiency increases only slightly from 370 to 410 Oe nm/V when MgO thickness increases from 1.5 to 1.76 nm. We have further observed the absence of quasi-DC unipolar switching. We discuss its origin and highlight the underlying challenges to implement the EF controlled switching in a practical magnetic memory.

  2. Effect of NiO spin orientation on the magnetic anisotropy of the Fe film in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, W.; Jin, E.; Wu, J.; Park, J.; Arenholz, E.; Scholl, A.; Hwang, C.; Qiu, Z.

    2010-02-10

    Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichroism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spin orientation changes from in-plane direction in Fe/NiO/Ag(001) to out-of-plane direction in Fe/NiO/MgO(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90{sup o}-coupling between the in-plane NiO spins and the in-plane Fe spins.

  3. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    K S Mallesh; Swarnamala Sirsi; Mahmoud A A Sbaih; P N Deepak; G Ramachandran

    2002-08-01

    We discuss the notion of spin squeezing considering two mutually exclusive classes of spin- states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin- states using 2 spinors oriented along different axes. Taking the case of = 1, we show that the `non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.

  4. Comparative randomized study on the efficaciousness of endoscopic bipolar prostate resection versus monopolar resection technique. 3 year follow-up

    OpenAIRE

    Roberto Giulianelli; Luca Albanesi; Francesco Attisani; Barbara Cristina Gentile; Giorgio Vincenti; Francesco Pisanti; Teuta Shestani; Luca Mavilla; David Granata; Manlio Schettini

    2013-01-01

    Objective: Transurethral resection of the prostate (TURP) is the current optimal thera- py for the relief of bladder outflow obstruction, with subjective and objective success rate of 85 to 90%. Aim of this study was to evaluate efficacy and safety of Plasmakinetic ener- gy (Gyrus electro surgical system), which produces vaporization of tissue immersed in isotonic saline against standard monopolar transurethral resection of the prostate. Methods: From January 2002 to April 2002, 160 consecuti...

  5. Osteoid osteoma of the spine: CT-guided monopolar radiofrequency ablation

    Energy Technology Data Exchange (ETDEWEB)

    Martel, Jose [Departamento de Diagnostico por Imagen, Fundacion Hospital Alcorcon, Alcorcon, Madrid (Spain)], E-mail: jmartel@fhalcorcon.es; Bueno, Angel [Departamento de Diagnostico por Imagen, Fundacion Hospital Alcorcon, Alcorcon, Madrid (Spain); Nieto-Morales, M Luisa [Servicio de Radiologia, Hospital Universitario de Tenerife (Spain); Ortiz, Eduardo J. [Departamento de Cirugia Ortopedica, Fundacion Hospital Alcorcon, Alcorcon, Madrid (Spain)

    2009-09-15

    CT-guided percutaneous radiofrequency ablation and laser photocoagulation have become the methods of choice for the treatment of all osteoid osteomas except those in contact with neural structures. We report 10 patients with spinal osteoid osteoma adjacent to the neural elements treated with 12 sessions of CT-guided monopolar radiofrequency ablation. The size range of the lesion was 3-14 mm (mean, 7.5 mm) and the distance between the nidus and the adjacent spinal cord or nerve root was 2-12 mm (mean, 5 mm). No intact cortex between the tumor and the spinal cord or nerve roots constituted an exclusion criterion because of a higher risk of undesirable neurotoxic effects. Patients were under general anesthesia. After location of the lesion, a 11G-bone biopsy was introduced into the nidus. The radiofrequency electrode was inserted through the biopsy needle and heated at 90 deg. C for 4 min. Primary success was obtained in eight patients. At follow-up (mean, 19.5 months; range, 6-24 months), pain persisted in two patients after 2 months. Both of them were re-treated. All patients are currently pain-free and complications were not detected. In our opinion, radiofrequency ablation can also be considered the treatment of choice for spinal osteoid osteoma.

  6. Multiple monopolar outflows driven by massive protostars in IRAS 18162-2048

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-López, M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Girart, J. M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain); Curiel, S.; Fonfría, J. P. [Instituto de Astronomía, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-264, 04510 México, DF (Mexico); Zapata, L. A. [Centro de Radioastronomía y Astrofísica, UNAM, Apartado Postal 3-72, Morelia, Michoacán 58089 (Mexico); Qiu, K., E-mail: manferna@illinois.edu, E-mail: girart@ieec.cat [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-11-20

    In this article, we present Combined Array for Research in Millimeter-wave Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 μm observations toward the high-mass star-forming region IRAS 18162-2048, which is the core of the HH 80/81/80N system. Molecular emission from HCN, HCO{sup +}, and SiO traces two molecular outflows (the so-called northeast and northwest outflows). These outflows have their origin in a region close to the position of MM2, a millimeter source known to harbor two protostars. For the first time we estimate the physical characteristics of these molecular outflows, which are similar to those of 10{sup 3}-5 × 10{sup 3} L {sub ☉} protostars, and suggest that MM2 harbors high-mass protostars. High-angular resolution CO observations show an additional outflow due southeast. Also for the first time, we identify its driving source, MM2(E), and see evidence of precession. All three outflows have a monopolar appearance, but we link the NW and SE lobes, and explain their asymmetric shape as being a consequence of possible deflection.

  7. Efficacy of monopolar dielectric transmission radio frequency in panniculus adiposus and cellulite reduction.

    Science.gov (United States)

    Albornoz-Cabello, Manuel; Ibáñez-Vera, Alfonso Javier; De la Cruz-Torres, Blanca

    2017-07-05

    Despite high incidence rate of cellulite, there are few studies regarding its treatment. Most of them present non-validated evaluation tools. Radio frequency is a focused treatment very used in aesthetics to reduce it. To know the efficacy of Monopolar Dielectric Radio frequency (MDR) treatment in dynamic applications to reduce cellulite, panniculus adiposus and gluteal and posterior thigh regions. Experimental study consisting of inferior members of nine women. They received 10 sessions based on dynamic applications of MDR. Variables included the following: Cellulite Severity Scale (CSS), appearance of the cutaneous area, flaccidity and ultrasound measurement of the panniculus adiposus. The final CSS score of the leg treated reflects statistically significative differences (p = 0.023) when compared with control leg (p = 0.622). Significant reductions of body perimeters at the level of the great trochanter (p = 0.02), the gluteal region (p = 0.03) and the midpoint of the posterior thigh (p = 0.01) are found. The reduction of the panniculus adiposus measured using ultrasound techniques shows significant changes in the midpoint of the posterior thigh (p = 0.028) as well as in the gluteal region (p = 0.03). The dynamic application of MDR seems to be effective in order to reduce not only the thickness of panniculus adiposus but also gluteal and posterior thigh perimeters.

  8. Multiple monopolar outflows driven by massive protostars in IRAS 18162-2048

    CERN Document Server

    Fernández-López, Manuel; Curiel, Salvador; Zapata, Luis Alberto; Fonfría, Jose Pablo; Qiu, Keping

    2013-01-01

    In this paper we present Combined Array for Research in Millimeter-wave Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 microns observations toward the high-mass star-forming region IRAS 1816-2048, the core of the HH 80/81/80N system. Molecular emission from HCN, HCO+ and SiO is tracing two molecular outflows (the so-called Northeast and Northwest outflows). These outflows have their origin in a region close to the position of MM2, a millimeter source known to harbor a couple protostars. We estimate for the first time the physical characteristics of these molecular outflows, which are similar to those of 1000-5000 Lo protostars, suggesting that MM2 harbors high-mass protostars. High-angular resolution CO observations show an additional outflow due southeast. We identify for the first time its driving source, MM2(E), and see evidence of precession. All three outflows have a monopolar appearance, but we link the NW and SE lobes, explaining their asymmetric shape as a consequence of possi...

  9. EDITORIAL: Optical orientation Optical orientation

    Science.gov (United States)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    priority of the discovery in the literature, which was partly caused by the existence of the Iron Curtain. I had already enjoyed contact with Boris in the 1980s when the two volumes of Landau Level Spectroscopy were being prepared [2]. He was one of the pioneers of magneto-optics in semiconductors. In the 1950s the band structure of germanium and silicon was investigated by magneto-optical methods, mainly in the United States. No excitonic effects were observed and the band structure parameters were determined without taking account of excitons. However, working with cuprous oxide, which is a direct semiconductor with a relative large energy gap, Zakharchenya and his co-worker Seysan showed that in order to obtain correct band structure parameters, it is necessary to take excitons into account [3]. About 1970 Boris started work on optical orientation. Early work by Hanle in Germany in the 1920s on the depolarization of luminescence in mercury vapour by a transverse magnetic field was not appreciated for a long time. Only in the late 1940s did Kastler and co-workers in Paris begin a systematic study of optical pumping, which led to the award of a Nobel prize. The ideas of optical pumping were first applied by Georges Lampel to solid state physics in 1968. He demonstrated optical orientation of free carriers in silicon. The detection method was nuclear magnetic resonance; optically oriented free electrons dynamically polarized the 29Si nuclei of the host lattice. The first optical detection of spin orientation was demonstrated by with the III-V semiconductor GaSb by Parsons. Due to the various interaction mechanisms of spins with their environment, the effects occurring in semiconductors are naturally more complex than those in atoms. Optical detection is now the preferred method to detect spin alignment in semiconductors. The orientation of spins in crystals pumped with circularly polarized light is deduced from the degree of circular polarization of the recombination

  10. Treatment of facial skin laxity by a new monopolar radiofrequency device

    Directory of Open Access Journals (Sweden)

    Uwe Wollina

    2011-01-01

    Full Text Available Background : Acquired facial skin laxity seems to be a result of the combination of intrinsic and extrinsic processes. For treatment of facial ageing, non-invasive procedures have become popular. Aim : We wanted to investigate the effect of a new 2.2-MHz radiofrequency (RF device on acquired facial skin laxity. Setting : Outpatient clinic associated with an academic teaching hospital. Materials and Methods : We performed an open trial with the RF-ReFacing™ device (Meyer-Haake Medical Innovations, Wehrheim/ Germany in the monopolar mode with a power of 8-12 W, two passes per session and repetition three times after 2 weeks without treatment. Results : A total of 20 Caucasian female patients were included (age range, 34-73 years. The procedure was performed without any analgesia. We did not see any adverse effect. The procedure was scored as most convenient or convenient by all patients. Improvement in skin laxity and fine wrinkles was seen after the second treatment in 19 of the 20 patients and after the third treatment in 100% of the patients. On a scale from 0 to 3, improvement in the lower lid, Crow′s feet and jowl line was scored 2.6±0.7 by the patients; improvement in the overall appearance of the face was scored 2.3±0.5. Blinded assessment of the photographs rated the improvement as good or better in 15 of the 20 patients, moderate in 3 patients, no change in 1 patient. Conclusions : RF-ReFacing™ treatment was effective in improvement in skin laxity. Patients′ satisfaction was high. Although RF-ReFacing™ treatment cannot substitute surgical procedure, it might prolong the time to the first surgical facial lift. The number of patients treated was small, and no quantitative measurements or histopathology was performed. Hence further studies with greater number of patients are necessary.

  11. Measuring the Orientation of Taurine in the Active Site of the Non-Heme Fe (II)/α-Ketoglutarate Dependent Taurine Hydroxylase (TauD) using Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy

    OpenAIRE

    Casey, Thomas M.; Grzyska, Piotr K.; Hausinger, Robert P.; McCracken, John

    2013-01-01

    The position and orientation of taurine near the non-heme Fe(II) center of the α-ketoglutarate (α-KG) dependent taurine hydroxylase (TauD) was measured using Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy. TauD solutions containing Fe(II), α-KG, and natural abundance taurine or specifically deuterated taurine were prepared anaerobically and treated with nitric oxide (NO) to make an S=3/2 {FeNO}7 complex that is suitable for robust analysis with EPR spectroscopy. Using ratios of E...

  12. Time-course of corticospinal excitability and autonomic function interplay during and following monopolar tDCS

    Directory of Open Access Journals (Sweden)

    Emiliano eSantarnecchi

    2014-07-01

    Full Text Available While polarity-specific after-effects of monopolar transcranial direct current stimulation (tDCS on cortico-spinal excitability are well-documented, modulation of vital parameters due to current spread through the brainstem is still a matter of debate, raising potential concerns about its use through the general public, as well as for neurorehabilitation purposes. We monitored online and after-effects of monopolar tDCS (primary motor cortex in ten healthy subjects by adopting a neuronavigated transcranial magnetic stimulation (TMS/tDCS combined protocol. Motor evoked potentials (MEPs together with vital parameters (e.g. blood pressure, heart-rate variability and sympathovagal balance were recorded and monitored before, during and after anodal, cathodal or sham tDCS. Ten MEPs every 2.5-minute time windows were recorded from the right First Dorsal Interosseus (FDI, while 5-minute epochs were used to record vital parameters. The protocol included 15 minutes of pre-tDCS and of online-tDCS, (anodal, cathodal or sham. After effects were recorded for 30 minutes. We showed a polarity-independent stabilization of cortical excitability level, a polarity-specific after-effects for cathodal and anodal stimulation, and an absence of persistent excitability changes during online stimulation. No significant effects on vital parameters emerged both during and after tDCS, while a linear increase in systolic/diastolic blood pressure and heart-rate variability was observed during each tDCS condition, as a possible unspecific response to experimental demands. Taken together, current findings provide new insights on the safety of monopolar tDCS, promoting its application both in research and clinical settings.

  13. COMPARATIVE STUDY OF FISTULECTOMY BY CORING TECHNIQUE IN FISTULA IN ANO, USING RADIOFREQUENCY CAUTERY AND MONOPOLAR CAUTERY

    Directory of Open Access Journals (Sweden)

    Madhura M

    2015-12-01

    Full Text Available Fistula in ano is common condition in perineal region. Anorectal fistulas are divided into four distinct types according to the Parks’ classification: intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric.1 The ultimate goal of fistula surgery is to eradicate it without disturbing or disturbing minimally the anal sphincter mechanism. The radiofrequency scalpel is an innovative instrument, which allows cutting and coagulating tissues in an atraumatic manner and which facilitates in accelerating and improving the surgical procedure conversely to the electric scalpel.2 This prospective study which will be conducted in a single centre and in this study we are comparing use of monopolar cautery and radiofrequency cautery units for the patients with fistula in ano operated during the period of February 2012 to February 2015. All fistulas will be treated by fistulectomy using coring technique. Results will be analyzed on following points like intraoperative bleeding, clearance of visual field, intra- and post-operative odema, and time required for every procedure, recurrence. AIMS AND OBJECTIVES OF STUDY 1. To compare intraoperative bleeding during surgery using both the units (cautery/RF cautery during surgery. 2. To assess clearance of field of vision intraoperatively. 3. To see for intraoperative and post-operative edema. 4. To assess time required for the procedure. 5. Final results in terms of recurrence. CONCLUSION Radiofrequency ablation is better method for fistulectomy compared to monopolar cautery in terms of intraoperative blood loss, post-operative pain, oedema, and healing period. But if procedure is better taken care of recurrence is avoidable. Operative time required for monopolar cautery exceeds radiofrequency cautery.

  14. Comparative randomized study on the efficaciousness of endoscopic bipolar prostate resection versus monopolar resection technique. 3 year follow-up

    Directory of Open Access Journals (Sweden)

    Roberto Giulianelli

    2013-06-01

    Full Text Available Objective: Transurethral resection of the prostate (TURP is the current optimal thera- py for the relief of bladder outflow obstruction, with subjective and objective success rate of 85 to 90%. Aim of this study was to evaluate efficacy and safety of Plasmakinetic ener- gy (Gyrus electro surgical system, which produces vaporization of tissue immersed in isotonic saline against standard monopolar transurethral resection of the prostate. Methods: From January 2002 to April 2002, 160 consecutive patients, who had low urinary tract symptoms (LUTS of benign prostatic hyperplasia (BPH were enrolled in this study. Patients were randomised to undergo bipolar TURP (80 patients or monopolar TURP (80 patients. Preoperative work-up was assessed by administering IPSS, IIEF-5 and Qol questionnaires. All patients were submitted to uroflowmetry, transrectal ultrasound (TRUS, post-voidal residual urine measurement and PSA determination. In the two groups, IPSS, IIEF-5 and Qol, uroflowme- try, TRUS, post-voidal residual urine measurement, PSA determination and number of reopera- tions were evaluated at 1, 3, 6, 12, 18, 24, 30 and 36 months follow up, and then every year. Furthermore, in both groups operative time, resected tissue weight and perioperative complica- tions were analysed. Total postoperative catheter time, total post-operative hospital stay, haemo- globin loss were also recorded in the two groups. Results: Comparative data on IPSS symptom score, IIEF-5, Qol, PSA, peak urinary flow rate and post-void residual urine volume were similar in the two groups but showed a significant improve- ment respect to baseline values. The postoperative haemoglobin levels, postoperative catheteri- zation time, hospital stay and 3-year overall surgical re-treatment-free rate were significantly better in the bipolar group. Conclusions: Bipolar TURP has a comparable outcome to standard monopolar TURP at short and medium term regard to subjective and objective outcome

  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. Comparative evaluation of transmembrane ion transport due to monopolar and bipolar nanosecond, high-intensity electroporation pulses based on full three-dimensional analyses

    Science.gov (United States)

    Hu, Q.; Joshi, R. P.

    2017-07-01

    Electric pulse driven membrane poration finds applications in the fields of biomedical engineering and drug/gene delivery. Here we focus on nanosecond, high-intensity electroporation and probe the role of pulse shape (e.g., monopolar-vs-bipolar), multiple electrode scenarios, and serial-versus-simultaneous pulsing, based on a three-dimensional time-dependent continuum model in a systematic fashion. Our results indicate that monopolar pulsing always leads to higher and stronger cellular uptake. This prediction is in agreement with experimental reports and observations. It is also demonstrated that multi-pronged electrode configurations influence and increase the degree of cellular uptake.

  17. Spin foams without spins

    Science.gov (United States)

    Hnybida, Jeff

    2016-10-01

    We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. In doing so the sums over spins have been carried out. The boundary data of each n-valent node is explicitly reduced with respect to the local gauge invariance and has a manifest geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.

  18. Monopolar high-frequency language mapping: can it help in the surgical management of gliomas? A comparative clinical study.

    Science.gov (United States)

    Riva, Marco; Fava, Enrica; Gallucci, Marcello; Comi, Alessandro; Casarotti, Alessandra; Alfiero, Tommaso; Raneri, Fabio A; Pessina, Federico; Bello, Lorenzo

    2016-05-01

    OBJECT Intraoperative language mapping is traditionally performed with low-frequency bipolar stimulation (LFBS). High-frequency train-of-five stimulation delivered by a monopolar probe (HFMS) is an alternative technique for motor mapping, with a lower reported seizure incidence. The application of HFMS in language mapping is still limited. Authors of this study assessed the efficacy and safety of HFMS for language mapping during awake surgery, exploring its clinical impact compared with that of LFBS. METHODS Fifty-nine patients underwent awake surgery with neuropsychological testing, and LFBS and HFMS were compared. Frequency, type, and site of evoked interference were recorded. Language was scored preoperatively and 1 week and 3 months after surgery. Extent of resection was calculated as well. RESULTS High-frequency monopolar stimulation induced a language disturbance when the repetition rate was set at 3 Hz. Interference with counting (p = 0.17) and naming (p = 0.228) did not vary between HFMS and LFBS. These results held true when preoperative tumor volume, lesion site, histology, and recurrent surgery were considered. Intraoperative responses (1603) in all patients were compared. The error rate for both modalities differed from baseline values (p language errors (articulatory, anomia, paraphasia) did not differ between the 2 stimulation methods (p = 0.279). CONCLUSIONS With proper setting adjustments, HFMS is a safe and effective technique for language mapping.

  19. Dissection by Ultrasonic Energy Versus Monopolar Electrosurgical Energy in Laparoscopic Cholecystectomy

    Science.gov (United States)

    2010-01-01

    Introduction: Laparoscopic cholecystectomy is the gold standard for management of symptomatic gallstones. Electrocautery remains the main energy form used during laparoscopic dissection. However, due to its risks, search is continuous for safer and more efficient forms of energy. This review assesses the effects of dissection using ultrasonic energy compared with monopolar electrocautery during laparoscopic cholecystectomy. Methods: A literature search of the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, and EMBASE was performed. Studies included were trials that prospectively randomized adult patients with symptomatic gallstone disease to either ultrasonic or monopolar electrocautery dissection during laparoscopic cholecystectomy. Data were collected regarding the characteristics and methodological quality of each trial. Outcome measures included operating time, gallbladder perforation rate, bleeding, bile leak, conversion rate, length of hospital stay and sick leave, postoperative pain and nausea scores, and influence on systemic immune and inflammatory responses. For metaanalysis, the statistical package RevMan version 4.2 was used. For continuous data, Weighted Mean Difference (WMD) was calculated with 95% confidence interval (CI) using the fixed effects model. For Categorical data, the Odds Ratio (OR) was calculated with 95% confidence interval using fixed effects model. Results: Seven trials were included in this review, with a total number of 695 patients randomized to 2 dissection methods: 340 in the electrocautery group and 355 in the ultrasonic group. No mortality was recorded in any of the trials. With ultrasonic dissection, operating time is significantly shorter in elective surgery (WMD −8.19, 95% CI −10.36 to −6.02, P>0.0001), acute cholecystitis (WMD −17, 95% CI −28.68 to −5.32, P=0.004), complicated cases (WMD −15, 95% CI −28.15 to −1.85, P=0.03), or if surgery was performed by trainee

  20. Slow spin relaxation in dipolar spin ice.

    Science.gov (United States)

    Orendac, Martin; Sedlakova, Lucia; Orendacova, Alzbeta; Vrabel, Peter; Feher, Alexander; Pajerowski, Daniel M.; Cohen, Justin D.; Meisel, Mark W.; Shirai, Masae; Bramwell, Steven T.

    2009-03-01

    Spin relaxation in dipolar spin ice Dy2Ti2O7 and Ho2Ti2O7 was investigated using the magnetocaloric effect and susceptibility. The magnetocaloric behavior of Dy2Ti2O7 at temperatures where the orientation of spins is governed by ``ice rules`` (T Tice) revealed thermally activated relaxation; however, the resulting temperature dependence of the relaxation time is more complicated than anticipated by a mere extrapolation of the corresponding high temperature data [1]. A susceptibility study of Ho2Ti2O7 was performed at T > Tice and in high magnetic fields, and the results suggest a slow relaxation of spins analogous to the behavior reported in a highly polarized cooperative paramagnet [2]. [1] J. Snyder et al., Phys. Rev. Lett. 91 (2003) 107201. [2] B. G. Ueland et al., Phys. Rev. Lett. 96 (2006) 027216.

  1. Knot spinning

    OpenAIRE

    Friedman, Greg

    2004-01-01

    This is an introduction to the construction of higher-dimensional knots by spinning methods. Simple spinning of classical knots was introduced by E. Artin in 1926, and several generalizations have followed. These include twist spinning, superspinning or p-spinning, frame spinning, roll spinning, and deform spinning. We survey these constructions and some of their most important applications, as well as some newer hybrids due to the author. The exposition, meant to be accessible to a broad aud...

  2. Optical manipulation of a multilevel nuclear spin in ZnO: Master equation and experiment

    Science.gov (United States)

    Buß, J. H.; Rudolph, J.; Wassner, T. A.; Eickhoff, M.; Hägele, D.

    2016-04-01

    We demonstrate the dynamics and optical control of a large quantum mechanical solid state spin system consisting of a donor electron spin strongly coupled to the 9/2 nuclear spin of 115In in the semiconductor ZnO. Comparison of electron spin dynamics observed by time-resolved pump-probe spectroscopy with density matrix theory reveals nuclear spin pumping via optically oriented electron spins, coherent spin-spin interaction, and quantization effects of the ten nuclear spin levels. Modulation of the optical electron spin orientation at frequencies above 1 MHz gives evidence for fast optical manipulation of the nuclear spin state.

  3. Spin Foams Without Spins

    CERN Document Server

    Hnybida, Jeff

    2015-01-01

    We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. Thus the sums over spins have been carried out. We focus on the character expansion of Yang-Mills theory which is an approximate heat kernel regularization of BF theory. The boundary data of each $n$-valent node is an element of the Grassmannian Gr(2,$n$) which carries a coherent representation of U($n$) and a geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.

  4. Monopolar fuel cell stack coupled together without use of top or bottom cover plates or tie rods

    Science.gov (United States)

    Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2009-01-01

    A monopolar fuel cell stack comprises a plurality of sealed unit cells coupled together. Each unit cell comprises two outer cathodes adjacent to corresponding membrane electrode assemblies and a center anode plate. An inlet and outlet manifold are coupled to the anode plate and communicate with a channel therein. Fuel flows from the inlet manifold through the channel in contact with the anode plate and flows out through the outlet manifold. The inlet and outlet manifolds are arranged to couple to the inlet and outlet manifolds respectively of an adjacent one of the plurality of unit cells to permit fuel flow in common into all of the inlet manifolds of the plurality of the unit cells when coupled together in a stack and out of all of the outlet manifolds of the plurality of unit cells when coupled together in a stack.

  5. Spin precession in anisotropic media

    Science.gov (United States)

    Raes, B.; Cummings, A. W.; Bonell, F.; Costache, M. V.; Sierra, J. F.; Roche, S.; Valenzuela, S. O.

    2017-02-01

    We generalize the diffusive model for spin injection and detection in nonlocal spin structures to account for spin precession under an applied magnetic field in an anisotropic medium, for which the spin lifetime is not unique and depends on the spin orientation. We demonstrate that the spin precession (Hanle) line shape is strongly dependent on the degree of anisotropy and on the orientation of the magnetic field. In particular, we show that the anisotropy of the spin lifetime can be extracted from the measured spin signal, after dephasing in an oblique magnetic field, by using an analytical formula with a single fitting parameter. Alternatively, after identifying the fingerprints associated with the anisotropy, we propose a simple scaling of the Hanle line shapes at specific magnetic field orientations that results in a universal curve only in the isotropic case. The deviation from the universal curve can be used as a complementary means of quantifying the anisotropy by direct comparison with the solution of our generalized model. Finally, we applied our model to graphene devices and find that the spin relaxation for graphene on silicon oxide is isotropic within our experimental resolution.

  6. Magnetization-orientation dependence of the superconducting transition in AF-F/S/F and S/F/F-AF type spin valve heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zdravkov, Vladimir [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of the Electronic Engineering and Nanotechnologies ASM, MD 2028 Kishiniev (Moldova, Republic of); Lenk, Daniel; Kehrle, Jan; Obermeier, Guenter; Ullrich, Aladin; Mueller, Claus; Krug von Nidda, Hans-Albrecht; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Morari, Roman; Sidorenko, Anatoli [D. Ghitsu Institute of the Electronic Engineering and Nanotechnologies ASM, MD 2028 Kishiniev (Moldova, Republic of); Tagirov, Lenar [Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation)

    2013-07-01

    In F/S/F spin valve core structures, i.e. Cu{sub 41}Ni{sub 59}/Nb/Cu{sub 41}Ni{sub 59} systems, deposited on an antiferromagnetic CoO{sub x} layer, or with such a layer on top, critical temperature oscillations and reentrant superconductivity are observed, which can be well described by the theory. Introducing a Co sub-layer yields exchange bias effects, which influence the magnetic field dependence of the superconducting transition. Aging effects are studied, which especially alter the transparency of the lower F/S interface, resulting in a change of the behavior of the transition temperature as a function of the ferromagnetic layer thickness from extinction, over reentrant, to oscillating. The results are discussed in comparison to the S/F/F-AF triplet spin valve effect in a Nb/Cu{sub 41}Ni{sub 59}/nc-Nb/Co/CoO{sub x} system, where nc-Nb acts as a normal conducting spacer to decouple the ferromagnetic layers.

  7. Bending strain engineering in quantum spin hall system for controlling spin currents

    Science.gov (United States)

    Huang, Bing; Jin, Kyung-Hwan; Cui, Bin; Zhai, Feng; Mei, Jiawei; Liu, Feng

    2017-06-01

    Quantum spin Hall system can exhibit exotic spin transport phenomena, mediated by its topological edge states. Here the concept of bending strain engineering to tune the spin transport properties of a quantum spin Hall system is demonstrated. We show that bending strain can be used to control the spin orientation of counter-propagating edge states of a quantum spin system to generate a non-zero spin current. This physics mechanism can be applied to effectively tune the spin current and pure spin current decoupled from charge current in a quantum spin Hall system by control of its bending curvature. Furthermore, the curved quantum spin Hall system can be achieved by the concept of topological nanomechanical architecture in a controllable way, as demonstrated by the material example of Bi/Cl/Si(111) nanofilm. This concept of bending strain engineering of spins via topological nanomechanical architecture affords a promising route towards the realization of topological nano-mechanospintronics.

  8. Oriented thin films of Na {sub 0.6}CoO {sub 2} and Ca {sub 3}Co {sub 4}O {sub 9} deposited by spin-coating method on polycrystalline substrate

    Energy Technology Data Exchange (ETDEWEB)

    Buršík, J., E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry ASCR, 250 68 Řež near Prague (Czech Republic); Soroka, M. [Institute of Inorganic Chemistry ASCR, 250 68 Řež near Prague (Czech Republic); Knížek, K.; Hirschner, J.; Levinský, P.; Hejtmánek, J. [Institute of Physics ASCR, Cukrovarnická 10, 162 00 Prague 6 (Czech Republic)

    2016-03-31

    Thin film of two thermoelectric materials, Na {sub x}CoO {sub 2} (x ~ 0.6) and Ca {sub 3}Co {sub 4}O {sub 9}, was deposited using the sol–gel spin-coating method on a polycrystalline yttria-stabilized zirconia (YSZ) substrate. Despite the polycrystalline character of the substrate, the c-axis preferred orientation was obtained, suggesting self-assembly growth mechanism. The deposition procedure used offers several benefits, namely simplicity, high deposition rate, low fabrication cost as well as low price of the substrate, and low thermal conductivity of the substrate suitable for characterization of thermoelectric properties and for applications. The thermoelectric properties of the thin films are comparable with bulk materials. The samples exhibit power factor 0.23 - 0.26 × 10{sup -3} W ⋅ m {sup -1} ⋅ K {sup -2} at 750 K. - Highlights: • Thin film of thermoelectric cobaltates was deposited using the spincoating method. • The c-axis preferred orientation was obtained on polycrystalline YSZ substrate. • Benefits of the chosen procedure are simplicity, low cost, and low thermal conductivity of the substrate.

  9. 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.

  10. Crystal orientation dependence of band matching in all-B2-trilayer current-perpendicular-to-plane giant magnetoresistance pseudo spin-valves using Co{sub 2}Fe(Ge{sub 0.5}Ga{sub 0.5}) Heusler alloy and NiAl spacer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiamin; Hono, K., E-mail: kazuhiro.hono@nims.go.jp [National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-2-1, Sengen, Tsukuba 305-0047 (Japan); Furubayashi, T.; Takahashi, Y. K.; Sasaki, T. T. [National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047 (Japan)

    2015-05-07

    We have experimentally investigated the crystal orientation dependence of band matching in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo-spin-valves using Co{sub 2}Fe(Ge{sub 0.5}Ga{sub 0.5}) (CFGG) Heusler alloy ferromagnetic layer and NiAl spacer. The high quality epitaxial CFGG/NiAl/CFGG all-B2-trilayers structure devices were fabricated on both MgO(001) and sapphire (112{sup ¯}0) single crystal substrates to create (001) and (110) crystal orientations. Same magneto-transport properties were observed from these two differently orientated devices indicating that there is no or little orientation dependence of band matching on MR output. We also found that all-B2-trilayer structure was free of lattice matching influence depending on the crystal orientation, which made it a good candidate for CPP-GMR device.

  11. Explicit Spin Coordinates

    CERN Document Server

    Hunter, G; Hunter, Geoffrey; Schlifer, Ian

    2005-01-01

    The recently established existence of spherical harmonic functions, $Y_\\ell^{m}(\\theta,\\phi)$ for half-odd-integer values of $\\ell$ and $m$, allows for the introduction into quantum chemistry of explicit electron spin-coordinates; i.e. spherical polar angles $\\theta_s, \\phi_s$, that specify the orientation of the spin angular momentum vector in space. In this coordinate representation the spin angular momentum operators, $S^2, S_z$, are represented by the usual differential operators in spherical polar coordinates (commonly used for $L^2, L_z$), and their electron-spin eigenfunctions are $\\sqrt{\\sin\\theta_s} \\exp(\\pm\\phi_s/2)$. This eigenfunction representation has the pedagogical advantage over the abstract spin eigenfunctions, $\\alpha, \\beta,$ that ``integration over spin coordinates'' is a true integration (over the angles $\\theta_s, \\phi_s$). In addition they facilitate construction of many electron wavefunctions in which the electron spins are neither parallel nor antiparallel, but inclined at an interme...

  12. Thermal creation of a spin current by Seebeck spin tunneling

    Science.gov (United States)

    Jansen, R.; Le Breton, J. C.; Deac, A. M.; Saito, H.; Yuasa, S.

    2013-09-01

    The thermoelectric analog of spin-polarized tunneling, namely Seebeck spin tunneling, is a recently discovered phenomenon that arises from the spin-dependent Seebeck coefficient of a magnetic tunnel contact. In a tunnel junction with one ferromagnetic electrode and one non-magnetic electrode, a temperature difference between the two electrodes creates a spin current across the contact. Here, the basic principle and the observation of Seebeck spin tunneling are described. It is shown how it can be used to create a spin accumulation in silicon driven by a heat flow across a magnetic tunnel contact, without a charge tunnel current. The sign of the spin current depends on the direction of the heat flow, whereas its magnitude is anisotropic, i.e., dependent on the absolute orientation of the magnetization of the ferromagnet. The connection between Seebeck spin tunneling and the tunnel magneto-Seebeck effect, observed in metal magnetic tunnel junctions, is also clarified. Seebeck spin tunneling may be used to convert waste heat into useful thermal spin currents that aid or replace electrical spin current, and thereby improve the energy efficiency of spintronic devices and technologies.

  13. Monopolar Radiofrequency Ablation for Medium-sized Hepatocellular Carcinoma: Preliminary Experience with Single-Electrode Overlapping Ablation and Multiple-Electrode Switching System

    Directory of Open Access Journals (Sweden)

    Shen-Yung Wang

    2015-03-01

    Conclusions: Medium-sized hepatocellular carcinoma can be effectively ablated with monopolar radiofrequency ablation by either single-electrode overlapping ablation or a multiple-electrode switching system. Regarding mid-term treatment responses, both RFA approaches can achieve similar treatment effectiveness, local tumor progression rate, and survival probabilities. Multiple-electrode switching RFA can treat larger medium-sized HCC with comparable mid-term efficacy as smaller medium-sized HCC treated with single-electrode overlapping RFA.

  14. An Immunomodulatory Protein (Ling Zhi-8 from a Ganoderma lucidum Induced Acceleration of Wound Healing in Rat Liver Tissues after Monopolar Electrosurgery

    Directory of Open Access Journals (Sweden)

    Hao-Jan Lin

    2014-01-01

    Full Text Available The purpose of this study was to investigate the effect of an immunomodulatory protein (Ling Zhi-8, LZ-8 on wound healing in rat liver tissues after monopolar electrosurgery. Animals were sacrificed for evaluations at 0, 3, 7, and 28 days postoperatively. It was found that the wound with the LZ-8 treatment significantly increases wound healing. Western blot analysis clearly indicated that the expression of NF-κB was decreased at 3, 7, and 28 days when liver tissues were treated with LZ-8. Moreover, caspase-3 activity of the liver tissue also significantly decreases at 7 and 28 days, respectively. DAPI staining and TUNEL assays revealed that only a minimal dispersion of NF-κB was found on the liver tissue treated with LZ-8 at day 7 as compared with day 3 and tissues without LZ-8 treatment. Similarly, apoptosis was decreased on liver tissues treated with LZ-8 at 7 days when compared to the control (monopolar electrosurgery tissues. Therefore, the analytical results demonstrated that LZ-8 induced acceleration of wound healing in rat liver tissues after monopolar electrosurgery.

  15. Comparative study of the safety and efficacy of liquid and dry monopolar electrocoagulation in experimental canine bleeding ulcers using computerized energy monitoring.

    Science.gov (United States)

    Swain, C P; Mills, T N; Dark, J M; Lewin, M R; Bown, S G; Northfield, T C; O'Sullivan, J P; Salmon, P R

    1984-01-01

    The drawbacks of monopolar electrocoagulation in the control of gastrointestinal bleeding include tissue adherence, unpredictable energy deposition, and a high incidence of tissue damage. Introduction of a conductive interfacial film of liquid between the monopolar electrode and the bleeding point during electrocoagulation may overcome these drawbacks. A prospective, controlled study was undertaken to evaluate the efficacy and safety of a monopolar electrode in liquid and dry modes when used to coagulate experimental canine bleeding ulcers. All experiments were done in open fashion via a gastrotomy with hand-held electrodes. An analog computer, which could be connected between a standard electrosurgical generator and the electrode, was designed and built to monitor and control the energy delivered to the tissue. Both liquid and dry electrodes were highly effective in stopping bleeding. The liquid electrode was found to be superior to the dry electrode in that tissue adherence was eliminated and energy deposition was more predictable, varying less with angle of incidence. The liquid electrode caused less macroscopic serosal damage and less full-thickness histologic damage if the total energy or number of pulses was limited; however, both caused microscopic full-thickness damage in one-half of the experimental ulcers treated, although no perforations occurred.

  16. Evidence for spin selectivity of triplet pairs in superconducting spin valves

    NARCIS (Netherlands)

    Banerjee, N.; Smiet, C.B.; Smits, R.G.J.; Ozaeta, A.; Bergeret, F.S.; Blamire, M.; Robinson, J.W.A.

    2013-01-01

    Spin selectivity in a ferromagnet results from a difference in the density of up- and down-spin electrons at the Fermi energy as a consequence of which the scattering rates depend on the spin orientation of the electrons. This property is utilized in spintronics to control the flow of electrons by f

  17. Measuring the orientation of taurine in the active site of the non-heme Fe(II)/α-ketoglutarate-dependent taurine hydroxylase (TauD) using electron spin echo envelope modulation (ESEEM) spectroscopy.

    Science.gov (United States)

    Casey, Thomas M; Grzyska, Piotr K; Hausinger, Robert P; McCracken, John

    2013-09-12

    The position and orientation of taurine near the non-heme Fe(II) center of the α-ketoglutarate (α-KG)-dependent taurine hydroxylase (TauD) was measured using Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy. TauD solutions containing Fe(II), α-KG, and natural abundance taurine or specifically deuterated taurine were prepared anaerobically and treated with nitric oxide (NO) to make an S = 3/2 {FeNO}(7) complex that is suitable for robust analysis with EPR spectroscopy. Using ratios of ESEEM spectra collected for TauD samples having natural abundance taurine or deuterated taurine, (1)H and (14)N modulations were filtered out of the spectra and interactions with specific deuterons on taurine could be studied separately. The Hamiltonian parameters used to calculate the amplitudes and line shapes of frequency spectra containing isolated deuterium ESEEM were obtained with global optimization algorithms. Additional statistical analysis was performed to validate the interpretation of the optimized parameters. The strongest (2)H hyperfine coupling was to a deuteron on the C1 position of taurine and was characterized by an effective dipolar distance of 3.90 ± 0.25 Å from the {FeNO}(7) paramagnetic center. The principal axes of this C1-(2)H hyperfine coupling and nuclear quadrupole interaction tensors were found to make angles of 26 ± 5 and 52 ± 17°, respectively, with the principal axis of the {FeNO}(7) zero-field splitting tensor. These results are discussed within the context of the orientation of substrate taurine prior to the initiation of hydrogen abstraction.

  18. Correlations and coherence of monopolar EMG-currents of the medial gastrocnemius muscle in proximal and distal compartments

    Directory of Open Access Journals (Sweden)

    Vinzenz eVon Tscharner

    2014-06-01

    Full Text Available The penniform gastrocnemius muscle contains multiple heads in the proximal regions and the aponeuroses are attached to the Achilles tendon. The multiple head structure lead to the assumption that different regions of the muscle must be activated compartment wise. The purpose of this study was to compare the correlation and coherence of EMG-currents within and between proximal and distal compartments of the medial gastrocnemius muscle, which reflect underling synchronization of motor units. It was hypothesized and shown that phase-inverted signals represent a property that discriminates compartments. However, the phase-inverted and non-inverted signals showed values of correlations that were indicative for highly synchronized signals. The correlation increased with the complexity of the task and was higher for the calf-rising movement than while balancing in a tiptoe position. Because the muscle fibers do not span the whole length of the muscles one has to conclude that the MUs were synchronized by synchronizing the various motor nerves. This study shows that it is essential to measure monopolar signals and use non-isometric contractions to observe synchronization of the EMG-signals. One could speculate that compartmental differences can only be observed if more complex movements that generate rotational forces at the knee or ankle are used.

  19. Effectiveness of electrocoagulation process in removing organic compounds from slaughterhouse wastewater using monopolar and bipolar electrolytic cells.

    Science.gov (United States)

    Asselin, Mélanie; Drogui, Patrick; Benmoussa, Hamel; Blais, Jean-François

    2008-08-01

    Slaughterhouse wastewaters contain varied and high amounts of organic matter (e.g., proteins, blood, fat). In order to produce an effluent suitable for stream discharge, electrochemical techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from poultry slaughterhouse (PS) effluent. Electrocoagulation (EC) process was tested using either mild steel or aluminium electrodes arranged in bipolar (BP) or monopolar configuration system. Results showed that the best performance was obtained using mild steel BP electrode system operated at a current intensity of 0.3A, through 60 or 90 min of treatment. Under these conditions, removals of 86+/-1% and 99+/-1% were measured for BOD and oil and grease, respectively, whereas soluble COD and total COD were removed by 50+/-4% and 82+/-2%, respectively. EC is also efficient for decolorization (red-color) and clarification of the PS effluent. Removals of 89+/-4% and 90+/-4% have been measured for total suspended solids and turbidity, respectively. Electrochemical coagulation operated under the optimal conditions involves a total cost of 0.71 USD $ per cubic meter of treated PS effluent. This cost includes energy and electrode consumptions, chemicals, and sludge disposal.

  20. Evaluation of the efficiency of monopolar and bipolar BDD electrodes for electrochemical oxidation of anthraquinone textile synthetic effluent for reuse.

    Science.gov (United States)

    Abdessamad, NourElHouda; Akrout, Hanene; Hamdaoui, Ghaith; Elghniji, Kais; Ksibi, Mohamed; Bousselmi, Latifa

    2013-10-01

    The efficiency of the electrochemical degradation of synthetic wastewater containing an anthraquinone dye has been comparatively studied in two electrolytic cells with a synthetic boron-doped diamond (Si/BDD) as an anode. The first is an individual cell (Cell 1) with monopolar electrode BDD and the second (Cell 2) has two bipolar electrodes BDD self-polarized. The bulk electrolysis was performed at the same initial operating conditions in order to quantify the influence of the initial pH and current density on dye discoloration and global mineralization removal. The current efficiency and the consumption energy were also evaluated. When the same solutions have been comparatively treated with the two cells, a quite good mineralization is found in Cell 2. This result supposed more fraction of the applied current is used for the electrocombustion reaction on Cell 2 if compared to Cell 1 and small amount rest for the side reaction of oxygen evolution. The HPLC analyses confirmed this hypothesis and showed that the concentration trend of intermediates (sulfanilic acid, phthalate acid and salicylic acid) with electrolysis time was different on two cells. Phototoxicity tests show that the electrochemical oxidation with BDD electrodes could be useful as a pretreatment technique for reducing hazardous wastewater toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. First Measurement of the {ital T}-Odd Correlation between the {ital Z}{sup 0} Spin and the Three-Jet Plane Orientation in Polarized {ital Z}{sup 0} Decays into Three Jets

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K.; Abt, I.; Ahn, C.J.; Akagi, T.; Allen, N.J.; Ash, W.W.; Aston, D.; Baird, K.G.; Baltay, C.; Band, H.R.; Barakat, M.B.; Baranko, G.; Bardon, O.; Barklow, T.; Bazarko, A.O.; Ben-David, R.; Benvenuti, A.C.; Bienz, T.; Bilei, G.M.; Bisello, D.; Blaylock, G.; Bogart, J.R.; Bolton, T.; Bower, G.R.; Brau, J.E.; Breidenbach, M.; Bugg, W.M.; Burke, D.; Burnett, T.H.; Burrows, P.N.; Busza, W.; Calcaterra, A.; Caldwell, D.O.; Calloway, D.; Camanzi, B.; Carpinelli, M.; Cassell, R.; Castaldi, R.; Castro, A.; Cavalli-Sforza, M.; Church, E.; Cohn, H.O.; Coller, J.A.; Cook, V.; Cotton, R.; Cowan, R.F.; Coyne, D.G.; D`Oliveira, A.; Damerell, C.J.S.; Daoudi, M.; De Sangro, R.; De Simone, P.; Dell`Orso, R.; Dima, M.; Du, P.Y.C.; Dubois, R.; Eisenstein, B.I.; Elia, R.; Falciai, D.; Fero, M.J.; Frey, R.; Furuno, K.; Gillman, T.; Gladding, G.; Gonzalez, S.; Hallewell, G.D.; Hart, E.L.; Hasegawa, Y.; Hedges, S.; Hertzbach, S.S.; Hildreth, M.D.; Huber, J.; Huffer, M.E.; Hughes, E.W.; Hwang, H.; Iwasaki, Y.; Jackson, D.J.; Jacques, P.; Jaros, J.; Johnson, A.S.; Johnson, J.R.; Johnson, R.A.; Junk, T.; Kajikawa, R.; Kalelkar, M.; Kang, H.J.; Karliner, I.; Kawahara, H.; Kendall, H.W.; Kim, Y.; King, M.E.; King, R.; Kofler, R.R.; Krishna, N.M.; Kroeger, R.S.; Labs, J.F.; Langston, M.; Lath, A.; Lauber, J.A.; Leith, D.W.G.; Liu, M.X.; Liu, X.; Loreti, M.; Lu, A.; Lynch, H.L.; Ma, J.; Mancinelli, G.; Manly, S.; Mantovani, G.; Markiewicz, T.W.; Maruyama, T.; Massetti, R.; Masuda, H.; Mattison, T.S.; Mazzucato, E.; McKemey, A.K.; Meadows, B.T.; Messner, R.; Mockett, P.M.; Moffeit, K.C.; Mours, B.; Mueller, G.; Muller, D.; Nagamine, T.; Nauenberg, U.; Neal, H.; Nussbaum, M.; Ohnishi, Y.; Osborne, L.S.; Panvini, R.S.; Park, H.; Pavel, T.J.; Peruzzi, I.; Piccolo, M.; Piemontese, L.; Pieroni, E.; Pitts, K.T.; Plano, R.J.; Prepost, R.; Prescott, C.Y.; Punkar, G.D.; Quigley, J.; Ratcliff, B.N.; Reeves, T.W.; Reidy, J.; Rensing, P.E.; Rochester, L.S.; Rothberg, J.E.; Rowson, P.C.; (SLD Collabor...

    1995-12-04

    We present the first measurement of the correlation between the {ital Z}{sup 0} spin and the event-plane orientation in polarized {ital Z}{sup 0} decays into three jets in the SLAC Linear Collider Large Detector experiment at SLAC utilizing a longitudinally polarized electron beam. The {ital CP}-even and {ital T}-odd triple product {ital {rvec S}}{sub {ital Z}}{center_dot}({ital {rvec k}}{sub 1}{times}{ital {rvec k}}{sub 2}), formed from the two fastest jet momenta {ital {rvec k}}{sub 1} and {ital {rvec k}}{sub 2} and the {ital Z}{sup 0} polarization vector {ital {rvec S}}{sub {ital Z}}, is sensitive to physics beyond the standard model. We measure the expectation value of this quantity to be consistent with zero and set 95% C.L. limits of {minus}0.022{lt}{beta}{lt}0.039 on the correlation. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  2. Spin waves in exchange-coupled double layers in the presence of spin torques

    Science.gov (United States)

    Baláž, Pavel; Barnaś, Józef

    2015-03-01

    Spin-wave spectra of a double magnetic layer are calculated theoretically in the macroscopic limit. Magnetic dynamics is described in terms of the Landau-Lifshitz-Gilbert equation, and both static (of the Ruderman-Kittel-Kasuya-Yosida type) and dynamic (via spin pumping) interlayer couplings are taken into account. The influence of spin pumping and spin transfer torque on the spin-wave spectra (frequency and damping factor) has been studied for both parallel and antiparallel magnetic configurations. The spin-wave spectrum in the parallel magnetic state is reciprocal, while in the antiparallel configuration it is nonreciprocal. In both cases, a substantial reduction of the spin-wave lifetimes due to spin pumping to the nonmagnetic metallic layers has been found. In the parallel configuration, this reduction appears mainly for optical modes, while in the antiparallel configuration, it is remarkable for all modes. In turn, the spin torque due to spin current flowing from a metallic layer, created for instance by the spin Hall effect, gives rise to significant changes in the damping factors as well, but these modifications depend on the sign of spin current. For one spin current orientation, the spin-wave damping becomes reduced and may disappear for some modes at a specific threshold value of the spin current, indicating magnetic instability in the system due to spin transfer torque. For the opposite spin current, the damping is enhanced, which indicates stabilization of the corresponding magnetic state.

  3. Spin dynamics in a two-dimensional quantum gas

    DEFF Research Database (Denmark)

    Pedersen, Poul Lindholm; Gajdacz, Miroslav; Deuretzbacher, Frank

    2014-01-01

    We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimp......We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions...

  4. Analytic definition of spin structure

    CERN Document Server

    Avetisyan, Zhirayr; Saveliev, Nikolai; Vassiliev, Dmitri

    2016-01-01

    We work on a parallelizable time-orientable Lorentzian 4-manifold and prove that in this case the notion of spin structure can be equivalently defined in a purely analytic fashion. Our analytic definition relies on the use of the concept of a non-degenerate two-by-two formally self-adjoint first order linear differential operator and gauge transformations of such operators. We also give an analytic definition of spin structure for the 3-dimensional Riemannian case.

  5. Danish orientalism

    National Research Council Canada - National Science Library

    Zerlang, Martin

    2006-01-01

    Orientalism became an important current in nineteenth-century Danish culture, but although it was contemporaneous with the orientalism of the leading European nations - Great Britain, France, Germany...

  6. Bipolar transurethral resection versus monopolar transurethral resection for benign prostatic hypertrophy: a systematic review and meta-analysis.

    Science.gov (United States)

    Tang, Yin; Li, Jinhong; Pu, Chuanxiao; Bai, YunJin; Yuan, HaiChao; Wei, Qiang; Han, Ping

    2014-09-01

    To evaluate the efficacy and safety of monopolar (M-TURP) and bipolar (B-TURP) transurethral resection of the prostate in benign prostatic hypertrophy (BPH) patients. Eligible randomized controlled trials (RCTs) were identified from electronic databases without language restrictions. Database search, quality assessment, and data extraction were independently performed. The primary postoperative outcomes of topical M-TURP and B-TURP were maximum flow rate (Qmax) and/or International Prostate Symptom Score (IPSS). Safety was estimated by TUR syndrome; need for transfusion; clot retention; bladder neck contracture (BNC); urethral stricture (US); and catheter removal time. Efficacy and safety were investigated using the Review Manager. Thirty-one trials met the inclusion criteria. Pooled analysis revealed significant difference in efficacy between the M-TURP and B-TURP groups. Safety analysis revealed significant improvement in the TUR syndrome with B-TURP than with M-TURP. Pooled analysis revealed that clot retention was significantly higher in M-TURP than in B-TURP. Moreover, pooled analysis revealed no significant difference between both groups in the blood transfusion frequency or late complications (urethral strictures) and bladder neck constriction. This systematic review indicates that B-TURP was significantly better in the result of Qmax and for decreasing the incidence of TUR syndrome and clot retention. No significant differences were observed in the nature of adverse events such as transfusions, retention after catheter removal, and urethral complications between both groups. Thus, B-TURP is the next generation "gold standard" for benign prostatic obstruction (BPO) because it is associated with a lower rate of clinically relevant complications such as TUR syndrome and clot retention.

  7. Monopolar Electro-Coagulation Process for Azo Dye C.I. Acid Red 18 Removal from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Ghasem Azarian

    2014-12-01

    Full Text Available The discharge of wastewaters containing an untreated dye results in aesthetic problems and an increase in gases solubility, which causes light transmission inhibition into water bodies. In spite of advantages of physicochemical and biological methods, these processes produce huge amounts of sludge, toxic by-products and require several oxidant chemicals. By contrast, electrochemical processes because of their high versatility, high efficiency and eco-friendly properties are more acceptable. In the present study, the removal of azo dye Acid Red 18 and chemical oxygen demand (COD from synthetic wastewater by monopolar (EC process was investigated and key parameters such as operating time, current density (CD, initial pH and energy, and electrode consumption were optimized. It was found that the process had a very good efficiency in the removal of both COD and color; for the iron electrode, the maximum amounts of color and COD removal were 99.5% and 59.0%, respectively. An operating time of 45 min, pH of 7 and CD of 1.2 mA/cm2 was selected as the optimized condition. The optimization of variables is extremely crucial as it results in a decrease in costs, energy and electrode consumption. Overall, the iron electrode used less energy than the aluminum electrode and was more acceptable for use in this process due to economical reasons. The findings of UV/vis spectra illustrated that the structures of this dye were removed by the process. In comparison with traditional methods such as aerobic and anaerobic systems, the EC process is a suitable alternative for the treatment of wastewaters containing dye pollutants.

  8. No-touch radiofrequency ablation: A comparison of switching bipolar and switching monopolar ablation in Ex Vivo bovine liver

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Won; Lee, Jeong Min; Lee, Sang Min; Hank, Joon Koo [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2017-04-15

    To evaluate the feasibility, efficiency, and safety of no-touch switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) using ex vivo bovine livers. A pork loin cube was inserted as a tumor mimicker in the bovine liver block; RFA was performed using the no-touch technique in the SM (group A1; 10 minutes, n = 10, group A2; 15 minutes, n = 10) and SB (group B; 10 minutes, n = 10) modes. The groups were compared based on the creation of confluent necrosis with sufficient safety margins, the dimensions, and distance between the electrode and ablation zone margin (DEM). To evaluate safety, small bowel loops were placed above the liver surface and 30 additional ablations were performed in the same groups. Confluent necroses with sufficient safety margins were created in all specimens. SM RFA created significantly larger volumes of ablation compared to SB RFA (all p < 0.001). The DEM of group B was significantly lower than those of groups A1 and A2 (all p < 0.001). Although thermal injury to the small bowel was noted in 90%, 100%, and 30% of the cases in groups A1, A2, and B, respectively, full depth injury was noted only in 60% of group A2 cases. The no-touch RFA technique is feasible in both the SB and SM modes; however, SB RFA appears to be more advantageous compared to SM RFA in the creation of an ablation zone while avoiding the unnecessary creation of an adjacent parenchymal ablation zone or adjacent small bowel injuries.

  9. No-Touch Radiofrequency Ablation: A Comparison of Switching Bipolar and Switching Monopolar Ablation in Ex Vivo Bovine Liver

    Science.gov (United States)

    Chang, Won; Lee, Sang Min; Han, Joon Koo

    2017-01-01

    Objective To evaluate the feasibility, efficiency, and safety of no-touch switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) using ex vivo bovine livers. Materials and Methods A pork loin cube was inserted as a tumor mimicker in the bovine liver block; RFA was performed using the no-touch technique in the SM (group A1; 10 minutes, n = 10, group A2; 15 minutes, n = 10) and SB (group B; 10 minutes, n = 10) modes. The groups were compared based on the creation of confluent necrosis with sufficient safety margins, the dimensions, and distance between the electrode and ablation zone margin (DEM). To evaluate safety, small bowel loops were placed above the liver surface and 30 additional ablations were performed in the same groups. Results Confluent necroses with sufficient safety margins were created in all specimens. SM RFA created significantly larger volumes of ablation compared to SB RFA (all p < 0.001). The DEM of group B was significantly lower than those of groups A1 and A2 (all p < 0.001). Although thermal injury to the small bowel was noted in 90%, 100%, and 30% of the cases in groups A1, A2, and B, respectively, full depth injury was noted only in 60% of group A2 cases. Conclusion The no-touch RFA technique is feasible in both the SB and SM modes; however, SB RFA appears to be more advantageous compared to SM RFA in the creation of an ablation zone while avoiding the unnecessary creation of an adjacent parenchymal ablation zone or adjacent small bowel injuries.

  10. Modulated spin polarization in nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, Sebastian; Oka, Hirofumi; Rodary, Guillemin; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)

    2009-07-01

    Deposition of 0.7 ML Co onto the clean Cu(111) surface at room temperature leads to the formation of triangular two atomic layers high Co islands. We study the electronic properties of these nano islands by scanning tunneling microscopy (STM) and spectroscopy (STS) at 7 K. We observe pronounced spatial modulation patterns in the local density of states (LDOS) within the islands due to electron confinement. We explore the magnetic properties of the very same islands by spin-polarized STM and STS in a magnetic field of up to 4 T. Our spin-polarized measurements in field clearly identify the parallel and anti-parallel spin orientation states of tip and sample. This enables us to measure the spatial distribution of the spin polarization within single Co islands. We find that the spin polarization is spatially modulated. Our results are discussed in view of recent theoretical predictions.

  11. Optical Implementation of Quantum Orienteering

    Science.gov (United States)

    Jeffrey, Evan R.; Altepeter, Joseph B.; Colci, Madalina; Kwiat, Paul G.

    2006-04-01

    We present results from an optical implementation of quantum orienteering, a protocol for communicating directions in space using quantum bits. We show how different types of measurements and encodings can be used to increase the communication efficiency. In particular, if Alice and Bob use two spin-1/2 particles for communication and employ joint measurements, they do better than is possible with local operations and classical communication. Furthermore, by using oppositely oriented spins, the achievable communication efficiency is further increased. Finally, we discuss the limitations of an optical approach: our results highlight the usually overlooked nonequivalence of different physical encodings of quantum bits.

  12. Investigation of the curvature induction and membrane localization of the influenza virus M2 protein using static and off-magic-angle spinning solid-state nuclear magnetic resonance of oriented bicelles.

    Science.gov (United States)

    Wang, Tuo; Hong, Mei

    2015-04-07

    A wide variety of membrane proteins induce membrane curvature for function; thus, it is important to develop new methods to simultaneously determine membrane curvature and protein binding sites in membranes with multiple curvatures. We introduce solid-state nuclear magnetic resonance (NMR) methods based on magnetically oriented bicelles and off-magic-angle spinning (OMAS) to measure membrane curvature and the binding site of proteins in mixed-curvature membranes. We demonstrate these methods on the influenza virus M2 protein, which not only acts as a proton channel but also mediates virus assembly and membrane scission. An M2 peptide encompassing the transmembrane (TM) domain and an amphipathic helix, M2(21-61), was studied and compared with the TM peptide (M2TM). Static (31)P NMR spectra of magnetically oriented 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) bicelles exhibit a temperature-independent isotropic chemical shift in the presence of M2(21-61) but not M2TM, indicating that the amphipathic helix confers the ability to generate a high-curvature phase. Two-dimensional (2D) (31)P spectra indicate that this high-curvature phase is associated with the DHPC bicelle edges, suggestive of the structure of budding viruses from the host cell. (31)P- and (13)C-detected (1)H relaxation times of the lipids indicate that the majority of M2(21-61) is bound to the high-curvature phase. Using OMAS experiments, we resolved the (31)P signals of lipids with identical headgroups based on their distinct chemical shift anisotropies. On the basis of this resolution, 2D (1)H-(31)P correlation spectra show that the amide protons in M2(21-61) correlate with the DMPC but not DHPC (31)P signal of the bicelle, indicating that a small percentage of M2(21-61) partitions into the planar region of the bicelles. These results show that the amphipathic helix induces high membrane curvature and localizes the protein to this phase, in good

  13. Investigation of the Curvature Induction and Membrane Localization of the Influenza Virus M2 Protein Using Static and Off-Magic-Angle Spinning Solid-State NMR of Oriented Bicelles

    Science.gov (United States)

    Wang, Tuo; Hong, Mei

    2015-01-01

    A wide variety of membrane proteins induce membrane curvature for function, thus it is important to develop new methods to simultaneously determine membrane curvature and protein binding sites in membranes with multiple curvatures. We introduce solid-state NMR methods based on magnetically oriented bicelles and off-magic-angle spinning (OMAS) to measure membrane curvature and the binding site of proteins in mixed-curvature membranes. We demonstrate these methods on the influenza virus M2 protein, which not only acts as a proton channel but also mediates virus assembly and membrane scission. An M2 peptide encompassing the transmembrane (TM) domain and an amphipathic helix, M2(21-61), was studied and compared with the TM peptide (M2TM). Static 31P NMR spectra of magnetically oriented DMPC/DHPC bicelles exhibit a temperature-independent isotropic chemical shift in the presence of M2(21-61) but not M2TM, indicating that the amphipathic helix confers the peptide with the ability to generate a high-curvature phase. 2D 31P spectra indicate that this high-curvature phase is associated with the DHPC bicelle edges, suggestive of the structure of budding viruses from the host cell. 31P- and 13C-detected 1H relaxation times of the lipids indicate that the majority of M2(21-61) is bound to the high-curvature phase. Using OMAS experiments, we resolved the 31P signals of lipids with identical headgroups based on their distinct chemical shift anisotropies. Based on this resolution, 2D 1H-31P correlation spectra show that the amide protons in M2(21-61) correlate with the DMPC but not the DHPC 31P signal of the bicelle, indicating that a small percentage of M2(21-61) partitions into the planar region of the bicelles. These results show that the M2 amphipathic helix induces high membrane curvature and localizes the protein to this phase, in excellent agreement with the membrane-scission function of the protein. These bicelle-based relaxation and OMAS solid-state NMR techniques are

  14. Modelado y Simulación del Procedimiento de Electrocirugía Monopolar Laparoscópica para Estimación de Riesgos en Pacientes

    OpenAIRE

    Valenzuela Bautista, Omar J.

    2004-01-01

    Esta tesis presenta un modelo de los riesgos a los que el paciente está expuesto durante una electrocirugía monopolar. Avances tecnológicos en el diseño de ESU´s (unidades de electrocirugía) proporcionan una alta confiabilidad en intervenciones quirÚrgicas mediante esta tecnología. El modelo implementado para representar los órganos internos involucrados en el procedimiento, así como el modelo para representar las extremidades del cuerpo humano están determinados por un circuito eléctrico RC....

  15. Artículo Original: Lesión tisular debida a dispersión térmica por el uso de electrodos monopolare

    OpenAIRE

    Azúa Córdova, Gonzalo; Zúñiga Montero, Marco; Chaves Chaves, Dennis; Quirós Alpízar, José Luis

    2016-01-01

    El uso de unidades de electrocirugía permite di-sección, corte y hemostasia debido al calor gene-rado por el flujo de la corriente eléctrica a través del tejido, efecto denominado diatermia. Este ca-lor, se difunde en un fenómeno conocido como dispersión térmica al tejido vecino, pudiendo le-sionarlo. Comparadas con otras modalidades, las unidades monopolares son las que producen ma-yor lesión tisular por dispersión térmica y dentro de las diferentes modalidades de uso que permiten estas unid...

  16. Comparación de las curvas de reclutamiento de unidades motoras extraídas con M-waves monopolares y bipolares

    OpenAIRE

    Erro Vicente, Leire

    2015-01-01

    El objetivo de este proyecto fin de máster es el estudio y caracterización de curvas de reclutamiento de unidades motoras a partir de M-waves monopolares y bipolares. En este proyecto, se registraron las M-waves de 20 sujetos masculinos de dos músculos del cuádriceps femoral (vasto lateral y vasto medial). A los sujetos se les aplicaron pulsos eléctricos de intensidad creciente desde los 10 mA hasta la intensidad que produce el reclutamiento completo de todas las unidades motoras....

  17. Spin multiplicities

    Energy Technology Data Exchange (ETDEWEB)

    Curtright, T.L., E-mail: curtright@miami.edu [Department of Physics, University of Miami, Coral Gables, FL 33124-8046 (United States); Van Kortryk, T.S., E-mail: vankortryk@gmail.com [Department of Physics, University of Miami, Coral Gables, FL 33124-8046 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439-4815 (United States); Zachos, C.K., E-mail: zachos@anl.gov [Department of Physics, University of Miami, Coral Gables, FL 33124-8046 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439-4815 (United States)

    2017-02-05

    The number of times spin s appears in the Kronecker product of n spin j representations is computed, and the large n asymptotic behavior of the result is obtained. Applications are briefly sketched. - Highlights: • We give a self-contained derivation of the spin multiplicities that occur in n-fold tensor products of spin-j representations. • We make use of group characters, properties of special functions, and asymptotic analysis of integrals. • We emphasize patterns that arise when comparing different values of j, and asymptotic behavior for large n. • Our methods and results should be useful for various statistical and quantum information theory calculations.

  18. Study on the Orientation of Liquid Crystals Presented on the Glass Substrates Spin-coated and Functionalized with Copper Ions%铜离子功能化的基底表面上液晶取向的研究

    Institute of Scientific and Technical Information of China (English)

    王诗鸣; 熊兴良; 张琰; 李广; 陈萌梦

    2013-01-01

    在液晶型化学与生物传感器的研究中,构建一个能使液晶分子长时间呈稳定、均一的取向排列且制作方法简易的基底表面对于传感器的实用化至关重要.本研究通过将5种不同浓度(0~ 100 mmol/L)的高氯酸铜无水乙醇溶液直接旋转喷涂于载玻片上,制备成具有化学敏感性的铜离子基底表面;随后将5CB液晶滴加在该基底表面,制作成液晶盒(液晶传感器);利用偏光显微镜的直光和锥光模式观察液晶分子的取向排列情况.实验发现在经过较短的时间后,旋涂有高氯酸铜的所有传感器的透射光斑先后逐渐变暗;高氯酸铜的浓度越大,光斑变暗的速度越快,完全变暗所需的时间越短;而未喷涂高氯酸铜的传感器在室温环境(25℃)下静置ld后,其透射光斑亮度没有变化;室温环境下于烘箱中贮存2个月后,喷涂有高氯酸铜的传感器的透射光亮度基本没有变化.结果表明,玻璃表面上直接喷涂高氯酸铜的基底表面能使液晶分子长时间呈稳定、均一的垂直排列;高氯酸铜的浓度对液晶取向排列的响应速度有影响.%A stable,uniform,easily implemented,LC-based chemical and biological sensor substrate for orientations of liquid crystals (LCs) for a long-term is urgently needed for medical applications of the sensors.We proposed a use of spin-coating of copper perchlorate (Cu (ClO4)2),with five different concentrations (0-100mmol/L),directly on glass slides for fabricating a layer of chemically-sensitive copper ions.Observing the transmitted light with a polarized microscope,we found the luminosity of the light propagated through sensors deposited with copper ions started to weaken gradually after a certain time.The higher was the concentration of copper ions covered on the glass substrates of the sensors,the faster the weakening occurred,and the less time was needed for transmitted light to turn completely dark.But there was no change in

  19. Spin-Spin Interactions in Organic Magnetoresistance Probed by Angle-Dependent Measurements

    Science.gov (United States)

    Wagemans, W.; Schellekens, A. J.; Kemper, M.; Bloom, F. L.; Bobbert, P. A.; Koopmans, B.

    2011-05-01

    The dependence of organic magnetoresistance (OMAR) on the orientation of the magnetic field has been investigated. In contrast with previous claims, a finite and systematic change in magnitude is observed when the orientation of the field is changed with respect to the sample. It is demonstrated that, to explain these effects, spin-spin interactions have to be included in the models previously suggested for OMAR. Dipole coupling and exchange coupling are introduced in combination with either an anisotropy of the orientation of the spin pairs or an anisotropy in the hyperfine fields.

  20. Spin foams

    CERN Document Server

    Engle, Jonathan

    2013-01-01

    The spin foam framework provides a way to define the dynamics of canonical loop quantum gravity in a spacetime covariant way, by using a path integral over histories of quantum states which can be interpreted as `quantum space-times'. This chapter provides a basic introduction to spin foams aimed principally at beginning graduate students and, where possible, at broader audiences.

  1. 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.

  2. Moderate MAS enhances local (1)H spin exchange and spin diffusion.

    Science.gov (United States)

    Roos, Matthias; Micke, Peter; Saalwächter, Kay; Hempel, Günter

    2015-11-01

    Proton NMR spin-diffusion experiments are often combined with magic-angle spinning (MAS) to achieve higher spectral resolution of solid samples. Here we show that local proton spin diffusion can indeed become faster at low (MAS (Clauss et al., 1993). The enhancement of spin diffusion by slow MAS relies on the modulation of the orientation-dependent dipolar couplings during sample rotation and goes along with transient level crossings in combination with dipolar truncation. The experimental finding and its explanation is supported by density matrix simulations, and also emphasizes the sensitivity of spin diffusion to the local coupling topology. The amplification of spin diffusion by slow MAS cannot be explained by any model based on independent spin pairs; at least three spins have to be considered. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Feynman propagator for spin foam quantum gravity.

    Science.gov (United States)

    Oriti, Daniele

    2005-03-25

    We link the notion causality with the orientation of the spin foam 2-complex. We show that all current spin foam models are orientation independent. Using the technology of evolution kernels for quantum fields on Lie groups, we construct a generalized version of spin foam models, introducing an extra proper time variable. We prove that different ranges of integration for this variable lead to different classes of spin foam models: the usual ones, interpreted as the quantum gravity analogue of the Hadamard function of quantum field theory (QFT) or as inner products between quantum gravity states; and a new class of causal models, the quantum gravity analogue of the Feynman propagator in QFT, nontrivial function of the orientation data, and implying a notion of "timeless ordering".

  4. 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.

  5. 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...

  6. Tratamiento quirúrgico curativo de la fibrilación atrial mediante técnica de ablación con radiofrecuencia monopolar irrigada: resultados a corto y mediano plazo Surgical treatment of atrial fibrillation through irrigated ablation with monopolar radiofrequency: results to short and midterm

    Directory of Open Access Journals (Sweden)

    Sergio Franco

    2007-02-01

    Full Text Available No existe una publicación colombiana con seguimiento a mediano plazo acerca del uso de esta técnica. Objetivo: evaluar el tratamiento quirúrgico de la fibrilación auricular a través de radiofrecuencia monopolar irrigada, mediante el seguimiento clínico, electrocardiográfico y ecocardiográfico a corto y mediano plazo. Métodos: entre septiembre de 2003 y octubre de 2005, se evaluaron de manera prospectiva, 70 pacientes con diagnóstico de fibrilación atrial y otra patología cardiaca que requería intervención quirúrgica. Se utilizó el sistema de ablación por radiofrecuencia monopolar Cardioblate® (Medtronic, Inc.. Los resultados se analizaron en un paquete estadístico SPSS versión 11,0. Resultados: se reclutaron 70 pacientes, 52% de género femenino y 48% masculino, con edad promedio de 54 años y fracción de expulsión preoperatoria del 47%. Se halló insuficiencia mitral (49% y estenosis mitral (26% como principales causas de cirugía cardiaca primaria. Se evaluaron 87% de los pacientes a 18 meses (3 y 25. Se logró la curación de la arritmia en el 88% de ellos. Las arritmias residuales en este grupo fueron fibrilación auricular (6% y flutter atrial (6%. El 80% de las arritmias post-operatorias se encuentran durante los primeros quince días de la cirugía; las más frecuentes fueron fibrilación atrial y flutter atrial. Se suspendió la anticoagulación y la medicación antiarrítmica en el 89% y 90% de los pacientes respectivamente. La técnica quirúrgica utilizada no generó complicaciones inherentes a la misma. Conclusión: esta investigación demostró que la técnica de ablación quirúrgica de la fibrilación auricular con radiofrecuencia monopolar irrigada, es fácilmente reproducible, altamente efectiva y segura para el paciente.There is not any publication about the use of this technique with midterm follow-up in Colombia. Objective: to evaluate the surgical treatment of atrial fibrillation with the use of

  7. Classical gravitational spin-spin interaction

    OpenAIRE

    Bonnor, W. B.

    2002-01-01

    I obtain an exact, axially symmetric, stationary solution of Einstein's equations for two massless spinning particles. The term representing the spin-spin interaction agrees with recently published approximate work. The spin-spin force appears to be proportional to the inverse fourth power of the coordinate distance between the particles.

  8. Exploring frustrated magnetism with artificial spin ice

    Science.gov (United States)

    Gilbert, Ian; Ilic, B. Robert

    2016-10-01

    Nanomagnet arrays known as artificial spin ice provide insight into the microscopic details of frustrated magnetism because, unlike natural frustrated magnets, the individual moments can be experimentally resolved and the lattice geometry can be easily tuned. Most studies of artificial spin ice focus on two lattice geometries, the square and the kagome lattices, due to their direct correspondence to natural spin ice materials such as Dy2Ti2O7. In this work, we review experiments on these more unusual lattice geometries and introduce a new type of nanomagnet array, artificial spin glass. Artificial spin glass is a two-dimensional array of nanomagnets with random locations and orientations and is designed to elucidate the more complex frustration found in spin glass materials.

  9. 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.

  10. Skein spaces and spin structures

    OpenAIRE

    Barrett, John W

    1995-01-01

    This paper relates skein spaces based on the Kauffman bracket and spin structures. A spin structure on an oriented 3-manifold provides an isomorphism between the skein space for parameter A and the skein space for parameter -A. There is an application to Penrose's binor calculus, which is related to the tensor calculus of representations of SU(2). The perspective developed here is that this tensor calculus is actually a calculus of spinors on the plane, and the matrices a re determined by a t...

  11. Monopolar versus bipolar transurethral resection of prostate for benign prostatic hyperplasia: Operative outcomes and surgeon preferences, a real-world scenario

    Science.gov (United States)

    Madduri, Vijay Kumar Sarma; Bera, Malay Kumar; Pal, Dilip Kumar

    2016-01-01

    Context: Monopolar transurethral resection of prostate (M-TURP) is considered the gold standard for the management of bladder outlet obstruction due to benign prostatic hyperplasia. Its newly introduced modification, bipolar TURP (B-TURP), promises to overcome its most prominent shortcomings, namely bleeding and dilutional hyponatremia. Literature is conflicting regarding merits of B-TURP over M-TURP. Aims: To find a difference, if any, in perioperative outcomes between M-TURP and B-TURP in a real-wold setting. Settings and Design: Prospective nonrandomized study. Subjects and Methods: Operative outcomes of patients undergoing M-TURP and B-TURP from February 2014 to October 2015 were compared. Statistical Analysis Used: Categorical data were compared by Fischer exact test and numerical data were compared by independent samples Mann–Whitney U-test. P <0.05 was considered statistically significant. Results: The mean size of prostate operated by bipolar technology was significantly greater than those operated by monopolar technology (38.12 ± 9.59 cc vs. 66.49 ± 22.95 cc; P < 0.001). The mean fall in postoperative serum sodium concentration was 0.99 ± 0.76 mEq/L for the B-TURP group as compared to 3.60 ± 2.89 mEq/L for the M-TURP group (P < 0.001). The mean drop in postoperative hemoglobin concentration (P = 0.28) was statistically insignificant, even though larger glands were operated by B-TURP. There were three instances of the transurethral resection (TUR) syndrome in the M-TURP group whereas no TUR syndrome occurred in the B-TURP group. Conclusions: In spite of various contrary viewpoints in literature, surgeons prefer to operate on larger prostates using bipolar technology. B-TURP definitely reduces the incidence of bleeding and dilutional hyponatremia, making it a contender to replace M-TURP as the new gold standard. PMID:27453650

  12. Bipolar plasma vaporization versus monopolar TUR and "cold-knife" TUI in secondary bladder neck sclerosis - an evidence based, retrospective critical comparison in a single center clinical setting.

    Science.gov (United States)

    Moldoveanu, C; Geavlete, B; Jecu, M; Stanescu, F; Adou, L; Bulai, C; Ene, C; Geavlete, P

    2014-03-15

    A long term, retrospective study was performed aiming to outline a critical comparison concerning the efficacy, safety and durability of the bipolar plasma vaporization (BPV), standard monopolar transurethral resection (TUR) and "cold-knife" "star" transurethral incision (TUI) in secondary bladder neck sclerosis (BNS) cases. Of the 126 patients included in the trial based on maximum flow rate (Qmax) below 10 mL/s and International Prostate Symptom Score (IPSS) over 19, classical resection was performed in 46 cases, "cold-knife" TUI in 37 cases and bipolar vaporization in 43 patients. The evaluation protocol comprised IPSS, QoL (quality of life) score, Qmax and PVR (post-voiding residual urinary volume) assessment performed at 1, 3, 6, 12, 18 and 24 months after the initial intervention. Significant intraoperative complications (capsular perforation - 8.7%; bleeding - 4.3%) occurred secondary to monopolar resection. "Star" TUI was the fastest technique, followed by plasma-button vaporization (7.2 and 11.4 versus 16.5 minutes). BPV and TUI patients benefitted from the shortest catheterization periods (0.75 and 1 versus 2.0 days) and hospital stays (1.0 and 1.25 versus 2.0 days). Immediate postoperative adverse events consisted of hematuria (6.5% of the TUR cases) and acute urinary retention (8.1% of the TUI group). Significantly higher long term BNS recurrence rates requiring re-treatment were established in the TUI (18.7%) and TUR (12.8%) series by comparison to BPV (5.4%). Among patients that completed the follow-up protocol, equivalent IPSS, QoL, Qmax and PVR features were determined in the 3 study arms. The plasma vaporization approach was confirmed as a successful match to conventional TUR and "cold-knife" TUI in terms of surgical safety profile, postoperative recovery, therapeutic durability and urodynamic and symptom score parameters.

  13. Orienteering injuries

    OpenAIRE

    Folan, Jean M.

    1982-01-01

    At the Irish National Orienteering Championships in 1981 a survey of the injuries occurring over the two days of competition was carried out. Of 285 individual competitors there was a percentage injury rate of 5.26%. The article discusses the injuries and aspects of safety in orienteering.

  14. A spin cell for spin current.

    Science.gov (United States)

    Sun, Qing-feng; Guo, Hong; Wang, Jian

    2003-06-27

    We propose and investigate a spin-cell device which provides the necessary spin-motive force to drive a spin current for future spintronic circuits. Our spin cell has four basic characteristics: (i) it has two poles so that a spin current flows in from one pole and out from the other pole, and in this way a complete spin circuit can be established; (ii) it has a source of energy to drive the spin current; (iii) it maintains spin coherence so that a sizable spin current can be delivered; (iv) it drives a spin current without a charge current. The proposed spin cell for spin current should be realizable using technologies presently available.

  15. Spin photocurrents in quantum wells

    CERN Document Server

    Ganichev, S D

    2003-01-01

    Spin photocurrents generated by homogeneous optical excitation with circularly polarized radiation in quantum wells (QWs) are reviewed. The absorption of circularly polarized light results in optical spin orientation due to the transfer of the angular momentum of photons to electrons of a two-dimensional electron gas. It is shown that in QWs belonging to one of the gyrotropic crystal classes a non-equilibrium spin polarization of uniformly distributed electrons causes a directed motion of electrons in the plane of the QW. A characteristic feature of this electric current, which occurs in unbiased samples, is that it reverses its direction upon changing the radiation helicity from left-handed to right-handed and vice versa. Two microscopic mechanisms are responsible for the occurrence of an electric current linked to a uniform spin polarization in a QW: the spin polarization-induced circular photogalvanic effect and the spin-galvanic effect. In both effects the current flow is driven by an asymmetric distribut...

  16. Spin pumping with coherent elastic waves

    Science.gov (United States)

    Weiler, M.; Huebl, H.; Goerg, F. S.; Czeschka, F. D.; Gross, R.; Goennenwein, S. T. B.

    2012-02-01

    The generation and detection of pure spin currents is an important topic for spintronic applications. Spin currents may be generated, e.g., via spin pumping. In this approach, a precessing magnetization relaxes via the emission of a spin current. Conventionally, electromagnetic waves, i.e. microwave photons, are used to drive the magnetization precession. We here show that a spin current can also be pumped by means of an acoustic wave, i.e. microwave phonons. In the experiments, coherent surface acoustic wave (SAW) phonons with a frequency of 1.55 GHz traverse a ferromagnetic thin film/normal metal (Co/Pt) bilayer. The SAW phonons drive the resonant magnetization precession via magnetoelastic coupling [1]. We use the inverse spin Hall voltage in the Pt film as a measure for the generated spin current and record its evolution as a function of time and external magnetic field magnitude and orientation. Our experiments show that a spin current is generated in the exclusive presence of a resonant elastic excitation. This establishes acoustic spin pumping as a resonant analogue to the spin Seebeck effect and opens intriguing perspectives for applications in, e.g., micromechanical resonators. [4pt] [1] M. Weiler et al., Phys. Rev. Lett. 106, 117601 (2011)

  17. Spin squeezing in nonlinear spin coherent states

    OpenAIRE

    Wang, Xiaoguang

    2001-01-01

    We introduce the nonlinear spin coherent state via its ladder operator formalism and propose a type of nonlinear spin coherent state by the nonlinear time evolution of spin coherent states. By a new version of spectroscopic squeezing criteria we study the spin squeezing in both the spin coherent state and nonlinear spin coherent state. The results show that the spin coherent state is not squeezed in the x, y, and z directions, and the nonlinear spin coherent state may be squeezed in the x and...

  18. Angular dependence of dipole-dipole-Curie-spin cross-correlation effects in high-spin and low-spin paramagnetic myoglobin.

    Science.gov (United States)

    Pintacuda, Guido; Hohenthanner, Karin; Otting, Gottfried; Müller, Norbert

    2003-10-01

    The (15)N-HSQC spectra of low-spin cyano-met-myoglobin and high-spin fluoro-met-myoglobin were assigned and dipole-dipole-Curie-spin cross-correlated relaxation rates measured. These cross-correlation rates originating from the dipolar (1)H-(15)N interaction and the dipolar interaction between the (1)H and the Curie spin of the paramagnetic center contain long-range angular information about the orientation of the (1)H-(15)N bond with respect to the iron-(1)H vector, with information measurable up to 11 A from the metal for the low-spin complex, and between 10 to 25 A for the high-spin complex. Comparison of the experimental data with predictions from crystal structure data showed that the anisotropy of the magnetic susceptibility tensor in low spin cyano-met-myoglobin significantly influences the cross-correlated dipole-dipole-Curie-spin relaxation rates.

  19. Cavity spin optodynamics

    CERN Document Server

    Brahms, N

    2010-01-01

    The dynamics of a large quantum spin coupled parametrically to an optical resonator is treated in analogy with the motion of a cantilever in cavity optomechanics. New spin optodynamic phenonmena are predicted, such as cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent amplification and damping of spin, and the spin optodynamic squeezing of light.

  20. Orientation and the Young Orienteer

    Science.gov (United States)

    Walsh, S. E.; Martland, J. R.

    Orientation within orienteering is dependent on the use of two basic strategies; that is, either a compass or Magnetic-North-based strategy, which relies on the use of one set of information; or the use of a map and landmark-based strategy which relies on the use of at least two sets of information. Walsh and found that, when given the choice, young children use the compass-based strategy when following complex potentially disorientating routes.The efficacy of these two basic orientation strategies was investigated within three different orienteering environments: (1) a familiar known environment; (2) a familiar unknown environment and (3) an unfamiliar unknown environment.Subjects, age range from 9 to 10think aloud particularly the introduction of basic skills to young performers. They support the argument that is essential to introduce the map and compass simultaneously and that relocation and orientation skills should be coached concurrently.

  1. Current heating induced spin Seebeck effect

    OpenAIRE

    Schreier, Michael; Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Gross, Rudolf; Goennenwein, Sebastian T. B.

    2013-01-01

    A new measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect ...

  2. Exotic orbits due to spin-spin coupling around Kerr black holes

    CERN Document Server

    Han, Wen-Bias

    2016-01-01

    We report exotic orbital phenomena for the case of spinning particles orbiting around a Kerr black hole, i.e., some orbits of spinning particles are asymmetrical about the equatorial plane. When a test particle orbits around a Kerr black hole in strong field region, due to the relativistic orbital precessions, the trajectories of this particle are symmetrical about the equatorial plane of the Kerr black hole. However, in some certain orbital configurations and artificially large spins, the trajectories of the spinning particle are no longer symmetrical about the equatorial plane. These asymmetrical motions come from the spin-spin interactions (Papapetrou force) between the spins of particle and black hole. By analyzing a spinning particle locating initially at the polar direction (i.e., z axis) of the Kerr black hole, we find that the spin-spin coupling with the certain spin orientation can produce a repulsive effect comparing with the one produced by mass. In generic orbits, the direction of Papapetrou force...

  3. Analyzing Orientations

    Science.gov (United States)

    Ruggles, Clive L. N.

    Archaeoastronomical field survey typically involves the measurement of structural orientations (i.e., orientations along and between built structures) in relation to the visible landscape and particularly the surrounding horizon. This chapter focuses on the process of analyzing the astronomical potential of oriented structures, whether in the field or as a desktop appraisal, with the aim of establishing the archaeoastronomical "facts". It does not address questions of data selection (see instead Chap. 25, "Best Practice for Evaluating the Astronomical Significance of Archaeological Sites", 10.1007/978-1-4614-6141-8_25) or interpretation (see Chap. 24, "Nature and Analysis of Material Evidence Relevant to Archaeoastronomy", 10.1007/978-1-4614-6141-8_22). The main necessity is to determine the azimuth, horizon altitude, and declination in the direction "indicated" by any structural orientation. Normally, there are a range of possibilities, reflecting the various errors and uncertainties in estimating the intended (or, at least, the constructed) orientation, and in more formal approaches an attempt is made to assign a probability distribution extending over a spread of declinations. These probability distributions can then be cumulated in order to visualize and analyze the combined data from several orientations, so as to identify any consistent astronomical associations that can then be correlated with the declinations of particular astronomical objects or phenomena at any era in the past. The whole process raises various procedural and methodological issues and does not proceed in isolation from the consideration of corroborative data, which is essential in order to develop viable cultural interpretations.

  4. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  5. 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.

  6. Spin-geodesic deviations in the Schwarzschild spacetime

    Science.gov (United States)

    Bini, Donato; Geralico, Andrea; Jantzen, Robert T.

    2011-04-01

    The deviation of the path of a spinning particle from a circular geodesic in the Schwarzschild spacetime is studied by an extension of the idea of geodesic deviation. Within the Mathisson-Papapetrou-Dixon model and assuming the spin parameter to be sufficiently small so that it makes sense to linearize the equations of motion in the spin variables as well as in the geodesic deviation, the spin-curvature force adds an additional driving term to the second order system of linear ordinary differential equations satisfied by nearby geodesics. Choosing initial conditions for geodesic motion leads to solutions for which the deviations are entirely due to the spin-curvature force, and one finds that the spinning particle position for a given fixed total spin oscillates roughly within an ellipse in the plane perpendicular to the motion, while the azimuthal motion undergoes similar oscillations plus an additional secular drift which varies with spin orientation.

  7. Spin-geodesic deviations in the Schwarzschild spacetime

    CERN Document Server

    Bini, Donato; Jantzen, Robert T

    2014-01-01

    The deviation of the path of a spinning particle from a circular geodesic in the Schwarzschild spacetime is studied by an extension of the idea of geodesic deviation. Within the Mathisson-Papapetrou-Dixon model and assuming the spin parameter to be sufficiently small so that it makes sense to linearize the equations of motion in the spin variables as well as in the geodesic deviation, the spin-curvature force adds an additional driving term to the second order system of linear ordinary differential equations satisfied by nearby geodesics. Choosing initial conditions for geodesic motion leads to solutions for which the deviations are entirely due to the spin-curvature force, and one finds that the spinning particle position for a given fixed total spin oscillates roughly within an ellipse in the plane perpendicular to the motion, while the azimuthal motion undergoes similar oscillations plus an additional secular drift which varies with spin orientation.

  8. Synchronous Spin-Exchange Optical Pumping

    CERN Document Server

    Korver, Anna; Bulatowicz, Mike; Walker, Thad

    2015-01-01

    We describe a new approach to precision NMR with hyperpolarized gases designed to mitigate NMR frequency shifts due to the alkali spin exchange field. The electronic spin polarization of optically pumped alkali atoms is square-wave modulated at the noble-gas NMR frequency and oriented transverse to the DC Fourier component of the NMR bias field. Noble gas NMR is driven by spin-exchange collisions with the oscillating electron spins. On resonance, the time-average torque from the oscillating spin-exchange field produced by the alkali spins is zero. Implementing the NMR bias field as a sequence of alkali 2$ \\pi $-pulses enables synchronization of the alkali and noble gas spins despite a 1000-fold discrepancy in gyromagnetic ratio. We demonstrate this method with Rb and Xe, and observe novel NMR broadening effects due to the transverse oscillating spin exchange field. When uncompensated, the spin-exchange field at high density broadens the NMR linewidth by an order of magnitude, with an even more dramatic suppre...

  9. Current heating induced spin Seebeck effect

    Energy Technology Data Exchange (ETDEWEB)

    Schreier, Michael, E-mail: michael.schreier@wmi.badw.de; Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Goennenwein, Sebastian T. B. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Gross, Rudolf [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, Technische Universität München, Garching (Germany)

    2013-12-09

    A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect.

  10. Spinning Particle Motion in a Kerr Geometry

    Science.gov (United States)

    Jones, A.; Baker, W. M.; Staton, R.

    1999-12-01

    The physics of particle motion in a Kerr geometry has been extensively studied. The case of motion of particles with spin is not as well investigated. We have studied the case of the motion of a spinning particle by applying the Papapetrou equation, which includes a spin-curvature coupling term, and an equation that describes the evolution of the spin of the particle. The motion is considered for a Kerr geometry in the weak field limit. We have obtained numerical solutions to this system of equations. Our results suggest that spin orientation is important for particle trajectories in a manner that is similar to the Stern-Gerlach effect. This could be important for the study of the motion of very low mass neutrinos. Project funded by a grant from the South Carolina Independent Colleges and Universities, and the Furman Advantage Program.

  11. Spin alignment of dark matter haloes in filaments and walls

    CERN Document Server

    Arag'on-Calvo, M A; Jones, B J T; Van der Hulst, T; Arag\\'on-Calvo, Miguel A.; Weygaert, Rien van de; Jones, Bernard J. T.

    2006-01-01

    The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host structures. The shape orientation is such that the halo minor axes tend to lie perpendicular to the host structure, be it a wall or filament. The orientation of the halo spin vector is mass dependent. Low mass haloes in walls and filaments have a tendency to have their spins oriented within the parent structure, while higher mass haloes in filaments have spins that tend to lie perpendicular to the parent structure.

  12. Perfect spin filtering effect in ultrasmall helical zigzag graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zi-Yue, E-mail: zzy8423@jiangnan.edu.cn

    2017-02-05

    The spin-polarized transport properties of helical zigzag graphene nanoribbons (ZGNRs) are investigated by first-principles calculations. It is found that although all helical ZGNRs have similar density of states and edge states, they show obviously different transport characteristics depending on the curling manners. ZGNRs curled along zigzag orientation exhibit perfect spin filtering effect with a large spin-split gap near the Fermi level, while ZGNRs curled along armchair orientation behave as conventional conductors for both two spin channels. The spin filtering effect will be weakened with the increase of either ribbon width or curling diameter. The results suggest that ultrasmall helical ZGNRs have important potential applications in spintronics and flexible electronics. - Highlights: • Perfect spin filtering effect has been found in helical ZGNRs. • The effect strongly depends on the curling manners of ZGNRs. • Different transport properties do not induced by distinct electronic properties. • The effect may be weakened with increasing either ribbon width or curling diameter.

  13. Spin currents, spin torques, and the concept of spin superfluidity

    Science.gov (United States)

    Rückriegel, Andreas; Kopietz, Peter

    2017-03-01

    In magnets with noncollinear spin configuration the expectation value of the conventionally defined spin current operator contains a contribution which renormalizes an external magnetic field and hence affects only the precessional motion of the spin polarization. This term, which has been named angular spin current by Sun and Xie [Phys. Rev. B 72, 245305 (2005)], 10.1103/PhysRevB.72.245305, does not describe the translational motion of magnetic moments. We give a prescription for how to separate these two types of spin transport and show that the translational movement of the spin is always polarized along the direction of the local magnetization. We also show that at vanishing temperature the classical magnetic order parameter in magnetic insulators cannot carry a translational spin current and elucidate how this affects the interpretation of spin supercurrents.

  14. Dimers on Surface Graphs and Spin Structures. I

    DEFF Research Database (Denmark)

    Cimasoni, David; Reshetikhin, Nicolai

    2007-01-01

    Partition functions for dimers on closed oriented surfaces are known to be alternating sums of Pfaffians of Kasteleyn matrices. In this paper, we obtain the formula for the coefficients in terms of discrete spin structures.......Partition functions for dimers on closed oriented surfaces are known to be alternating sums of Pfaffians of Kasteleyn matrices. In this paper, we obtain the formula for the coefficients in terms of discrete spin structures....

  15. Spin tune mapping as a novel tool to probe the spin dynamics in storage rings

    Science.gov (United States)

    Saleev, A.; Nikolaev, N. N.; Rathmann, F.; Augustyniak, W.; Bagdasarian, Z.; Bai, M.; Barion, L.; Berz, M.; Chekmenev, S.; Ciullo, G.; Dymov, S.; Eversmann, D.; Gaisser, M.; Gebel, R.; Grigoryev, K.; Grzonka, D.; Guidoboni, G.; Heberling, D.; Hejny, V.; Hempelmann, N.; Hetzel, J.; Hinder, F.; Kacharava, A.; Kamerdzhiev, V.; Keshelashvili, I.; Koop, I.; Kulikov, A.; Lehrach, A.; Lenisa, P.; Lomidze, N.; Lorentz, B.; Maanen, P.; Macharashvili, G.; Magiera, A.; Mchedlishvili, D.; Mey, S.; Müller, F.; Nass, A.; Pesce, A.; Prasuhn, D.; Pretz, J.; Rosenthal, M.; Schmidt, V.; Semertzidis, Y.; Senichev, Y.; Shmakova, V.; Silenko, A.; Slim, J.; Soltner, H.; Stahl, A.; Stassen, R.; Stephenson, E.; Stockhorst, H.; Ströher, H.; Tabidze, M.; Tagliente, G.; Talman, R.; Engblom, P. Thörngren; Trinkel, F.; Uzikov, Yu.; Valdau, Yu.; Valetov, E.; Vassiliev, A.; Weidemann, C.; Wrońska, A.; Wüstner, P.; Zuprański, P.; Zurek, M.; JEDI Collaboration

    2017-07-01

    Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called spin tune mapping, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 using polarized deuterons stored in the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than 2.8 μ rad .

  16. Orienteering club

    CERN Document Server

    Club d'orientation

    2015-01-01

    Course d'orientation La reprise des courses d’orientation était attendue dans la région puisque près de 150 coureurs ont participé à la première épreuve automnale organisée par le club d’orientation du CERN sur le site de La Faucille. Les circuits ont été remportés par Yann Locatelli du club d’Orientation Coeur de Savoie avec 56 secondes d’avance sur Damien Berguerre du club SOS Sallanches pour le parcours technique long, Marie Vuitton du club CO CERN (membre également de l’Equipe de France Jeune) pour le parcours technique moyen avec presque 4 minutes d’avance sur Jeremy Wichoud du club Lausanne-Jorat, Victor Dannecker pour le circuit technique court devant Alina Niggli, Elliot Dannecker pour le facile moyen et Alice Merat sur le facile court, tous membres du club O’Jura. Les résultats comp...

  17. Three-phase shots and monopolar reclose in the core network of 400 kV of the Area de Control Occidental of CFE and Its normal probability of occurrence; Disparos trifasicos y de recierre monopolar en la red troncal de 400 kV del area de control occidental, CFE, y su probabilidad normal de ocurrencia

    Energy Technology Data Exchange (ETDEWEB)

    Narvaez Perez, Camilo; Garcia Conejo, Dante Aristoteles [Comision Federal de Electricidad, Centro Nacional de Control de Energia, Area de Control Occidental, Zapopan, Jalisco (Mexico)]. E-mail: camilo.narvaez@cfe.gob.mx; camilo.narvaez@univa.mx; Ramirez Peredo, Patricia [Universidad de Guadalajara, Guadalajara, Jalisco (Mexico)]. E-mail: patyrape@hotmail.com; Blanco Gomez, Cesar Eduardo [Comision Federal de Electricidad, Centro Nacional de Control de Energia, Area de Control Occidental, Zapopan, Jalisco (Mexico)

    2013-03-15

    The growing power demand of users, who make loads of power systems, causes the components of such systems operating near its operating limits. And the transmission line, being the most common component in these, requires a thorough analysis in regard to the probability of three-phase shots and monopolars reclosing, considering thunderstorms, the demand system time, the flows circulating in lines, maintenance on other lines and other imponderantes. This research analyzes the normal probability of occurrence of shots in the 400 kV core network of the Area de Control Occidental, CFE and its impact on studies conducted prior to the maintenance. We intend to use the methodology in the Comision Federal de Electricidad and results can be validated with data from previous years, based on a pseudo shots forecast in a given period. [Spanish] La creciente demanda de energia electrica de los usuarios que componen las cargas de los sistemas electricos de potencia, provoca que los componentes de dichos sistemas funcionen cerca de sus limites operativos. Y la linea de transmision, al ser el componente mas comun en estos, requiere de un analisis minucioso en lo que respecta a la probabilidad de disparos trifasicos y recierres monopolares, considerando tormentas electricas, la demanda horaria del sistema, los flujos que circulan en las lineas, los mantenimientos en las demas lineas y demas imponderantes. En esta investigacion se analiza la probabilidad normal de ocurrencia de disparos en la red troncal de 400 kV del Area de Control Occidental y su impacto en los estudios que se realizan previos a los mantenimientos. Se pretende utilizar la metodologia en la Comision Federal de Electricidad, y los resultados pueden ser validados con datos de los anos anteriores, ya que se hace un pseudo pronostico de disparos en un periodo dado.

  18. Correction of phase errors in quantitative water-fat imaging using a monopolar time-interleaved multi-echo gradient echo sequence.

    Science.gov (United States)

    Ruschke, Stefan; Eggers, Holger; Kooijman, Hendrik; Diefenbach, Maximilian N; Baum, Thomas; Haase, Axel; Rummeny, Ernst J; Hu, Houchun H; Karampinos, Dimitrios C

    2017-09-01

    To propose a phase error correction scheme for monopolar time-interleaved multi-echo gradient echo water-fat imaging that allows accurate and robust complex-based quantification of the proton density fat fraction (PDFF). A three-step phase correction scheme is proposed to address a) a phase term induced by echo misalignments that can be measured with a reference scan using reversed readout polarity, b) a phase term induced by the concomitant gradient field that can be predicted from the gradient waveforms, and c) a phase offset between time-interleaved echo trains. Simulations were carried out to characterize the concomitant gradient field-induced PDFF bias and the performance estimating the phase offset between time-interleaved echo trains. Phantom experiments and in vivo liver and thigh imaging were performed to study the relevance of each of the three phase correction steps on PDFF accuracy and robustness. The simulation, phantom, and in vivo results showed in agreement with the theory an echo time-dependent PDFF bias introduced by the three phase error sources. The proposed phase correction scheme was found to provide accurate PDFF estimation independent of the employed echo time combination. Complex-based time-interleaved water-fat imaging was found to give accurate and robust PDFF measurements after applying the proposed phase error correction scheme. Magn Reson Med 78:984-996, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  19. Dimers on surface graphs and spin structures. II

    DEFF Research Database (Denmark)

    Cimasoni, David; Reshetikhin, Nicolai

    2009-01-01

    In a previous paper [3], we showed how certain orientations of the edges of a graph Γ embedded in a closed oriented surface Σ can be understood as discrete spin structures on Σ. We then used this correspondence to give a geometric proof of the Pfaffian formula for the partition function of the di......In a previous paper [3], we showed how certain orientations of the edges of a graph Γ embedded in a closed oriented surface Σ can be understood as discrete spin structures on Σ. We then used this correspondence to give a geometric proof of the Pfaffian formula for the partition function...... of the dimer model on Γ. In the present article, we generalize these results to the case of compact oriented surfaces with boundary. We also show how the operations of cutting and gluing act on discrete spin structures and how they change the partition function. These operations allow to reformulate the dimer...

  20. Sexual Orientation (For Parents)

    Science.gov (United States)

    ... Teaching Kids to Be Smart About Social Media Sexual Orientation KidsHealth > For Parents > Sexual Orientation Print A ... orientation is part of that process. What Is Sexual Orientation? The term sexual orientation refers to the ...

  1. Optical nuclear spin polarization in quantum dots

    Science.gov (United States)

    Li, Ai-Xian; Duan, Su-Qing; Zhang, Wei

    2016-10-01

    Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot (QD) by the coherent population trapping (CPT) and the electric dipole spin resonance (EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip-flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time. Project partially supported by the National Natural Science Foundations of China (Grant Nos. 11374039 and 11174042) and the National Basic Research Program of China (Grant Nos. 2011CB922204 and 2013CB632805).

  2. Relativistic Spin Operators

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng-Fei; RUAN Tu-Nan

    2001-01-01

    A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativistic one, which is called in this paper as moving spin. Further the concept of moving spin is discussed in the quantum field theory. A new is constructed. It is shown that, in virtue of the two operators, problems in quantum field concerned spin can be neatly settled.

  3. Effects of monopolar electrocoagulation and bipolar electrocoagulation in laparoscopy for infertility on ovarian function%腹腔镜不孕症手术使用单、双极电凝对卵巢功能的影响

    Institute of Scientific and Technical Information of China (English)

    李建华

    2011-01-01

    目的:探讨腹腔镜不孕症手术中使用单、双极电凝对卵巢功能的影响.方法:选择100例因输卵管因素导致的不孕症患者,均行腹腔镜下输卵管的修复整形手术,使用不同的止血方法随机分为单极电凝组50例、双极电凝组50例.分别于术前、术后1、3个月抽血检测促卵泡激素(FSH)、黄体生成素(LH)、雌二醇(E2),月经第11天开始B超监测排卵情况,术后随访1年.结果:两组病例术后1、3个月较术前均出现不同程度的FSH、LH增高和E2下降,单极电凝组与术前比较差异有统计学意义(P<0.05),双极电凝组与术前比较差异无统计学意义(P>0.05).结论:腹腔镜下不孕症手术中使用单、双极电凝止血会引起对卵巢功能的损害,而使用单极电凝止血对卵巢功能的损害较使用双极电凝止血大.单极电凝组术后发生月经改变明显多于双极电凝组(P<0.05).双极电凝组术后妊娠率较单极电凝组高.%Objective: To explore the effects of monopolar electrocoagulation and bipolar electrocoagulation in laparoscopy for infertility on ovarian function. Methods: 100 infertile patients because of tubal factor were selected, and all the patients received fallopian tube surgery under laparoscope, then they were divided into monopolar electrocoagulation group ( 50 women) and bipolar electrocoagulation group (50 women) according to different hemostatic methods. Their blood samples were obtained to detect the levels of follicle - stimulating hormone ( FSH) , luteinizing hormone ( LH ) and estradiol before surgery, at one and three months after surgery, B ultrasound was used to monitor the ovulation situation from the eleventh day of menstrual cycle, all the patients were followed up for one year after surgery. Results: Compared with before surgery, the levels of FSH and LH at one and three months after surgery increased, the level of estradiol decreased, there was significant difference in monopolar

  4. Spin transport and spin-flip scattering in magnetic multilayer structures

    Science.gov (United States)

    Garzon, Samir

    2006-03-01

    The existence of spin-flip scattering at the interface between ferromagnetic (F) and nonmagnetic (N) layers of magnetoresistive F/N/F structures can significantly reduce the size of the magnetoresistance, limiting the sensitivity and increasing the power consumption of F/N/F devices such as GMR magnetic field sensors, magnetic read heads, and MRAM's [1]. Detecting and measuring the degree of spin flip scattering in F/N/F structures can allow further optimization in such devices as well as increase the understanding of interfacial spin transport. Our nonlocal spin injection and detection experiments on mesoscopic Co-Al2O3-Cu-Al2O3-Co spin valves provide evidence for the existence of interfacial spin-flip scattering in magnetoresistive devices [2]. By extending the conventional picture of spin-dependent interfacial resistances (R, R) to include two additional spin-flip scattering channels (R,R) [3] we have shown that the nonlocal resistance contains information about both the degree of spin polarization and the degree of spin-flip scattering at the F/N interface. The magnitudes of R and R depend on the relative orientation of the detector magnetization and the nonequilibrium magnetization in the normal metal. We have observed that the difference in spin-flip scattering between up and down channels vanishes at low temperatures, but for T>100K it increases nonlinearly with temperature. Further evidence for the presence of interfacial spin-flip scattering can be obtained from noise measurements, which are extremely sensitive to the microscopic transport details. [1] Spin Dependent Transport in Magnetic Nanostructures, edited by S. Maekawa and T. Shinjo (Taylor & Francis, New York, 2002). [2] S. Garzon, I. Zuti'c, and R. A. Webb, Phys. Rev. Lett. 94, 176601 (2005). [3] E. I. Rashba, Eur. Phys. J. B 29, 513 (2002).

  5. Undergraduate Electron-Spin-Resonance Experiment.

    Science.gov (United States)

    Willis, James S.

    1980-01-01

    Describes the basic procedures for use of an electron-spin resonance spectrometer and potassium azide (KN3) in an experiment which extends from the phase of sample preparation (crystal growth, sample mounting, and orientation) through data taking to the stages of calculation and theoretical explanation. (Author/DS)

  6. Orienteering Club

    CERN Document Server

    Club d'orientation

    2013-01-01

    Courses d’orientation Une bonne dizaine de clubs étaient représentés samedi dernier à La Faucille pour participer à la  2e manche de la coupe genevoise organisée par le club du CERN. Les 120 coureurs ont pu découvrir des parcours classés "technique". Ceux du Haut-Jura familiarisés à ce type de terrain ont pu sortir leur épingle du jeu et se sont octroyé la victoire sur 4 des 5 circuits. Samedi 21 septembre, la montagne du Haut-Jura était encore plébiscitée puisque les coureurs étaient attendus à Saint Cergue sur la carte des Pralies. Pour les résultats complets de La Faucille et les informations sur la prochaine étape, consultez le site du club http://cern.ch/club-orientation.

  7. Orientation Club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    COURSE ORIENTATION Résultats de samedi 10 mai    C’est sur une carte entièrement réactualisée dans les bois de Versoix, que plus de 100 coureurs sont venus participer à la course d’orientation, type longue distance, préparée par des membres du club du CERN. Le terrain plutôt plat nécessitait une orientation à grande vitesse, ce qui a donné les podiums suivants :  Technique long avec 17 postes : 1er Jurg Niggli, O’Jura en 52:48, 2e Beat Muller, COLJ Lausanne-Jorat en 58:02, 3e Christophe Vuitton, CO CERN en 58:19 Technique moyen avec 13 postes : 1er Jean-Bernard Zosso, CO CERN, en 46:05 ; 2e Yves Rousselot, Balise 25 Besançon, en 55:11 ; 3e Laurent Merat, O'Jura, en 55:13 Technique court avec 13 postes : 1er Julien Vuitton, CO CERN en 40:59, 2e Marc Baumgartner, CO CERN en 43:18, 3e Yaelle Mathieu en 51:42 Su...

  8. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation ce printemps Le Club d’orientation du CERN vous invite à venir découvrir la course d’orientation et vous propose, en partenariat avec d’autres clubs de la région, une dizaine de courses populaires. Celles-ci ont lieu les samedis après-midi, elles sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Si vous êtes débutant vous pouvez profiter d’une petite initiation offerte par l’organisateur avant de vous lancer sur un parcours. Divers types de parcours sont à votre choix lors de chaque épreuve : facile court (2-3 km), facile moyen (3-5 km), technique court (3-4 km), technique moyen (4-5 km) et technique long (5-7 km). Les dates à retenir sont les suivantes : Samedi 23 mars: Pully (Vd) Samedi 13 avril: Pougny...

  9. Spin-Flip of Polaron in Polymers with a Magnetic Impurity

    Institute of Scientific and Technical Information of China (English)

    CHEN Mei-Juan; YAN Yong-Hong; WU Chang-Qin

    2007-01-01

    Using a nonadiabatic evolution method, we investigate the spin-nip process ofpolaron in polymers with a magnetic impurity. Our results show that when the spin orientation of this impurity is fixed to be perpendicular to the spin ofpolaron (θ=π/2), the magnetic impurity causes a spin-flip process. The probability of the spin-Sip increases with the increase of exchange integral J up to about 0.35 eV and then decreases with the increase of J. In the case J is fixed while the spin orientation is adjustable, we find the probability of the spin-flip varies with the impurity orientation and reaches a maximum value at θ=π/2.

  10. 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.

  11. Cross polarization from spins I=12 to spins S=1 in nuclear magnetic resonance with magic angle sample spinning.

    Science.gov (United States)

    Gopalakrishnan, Karthik; Bodenhausen, Geoffrey

    2006-05-21

    Spin locking of the nuclear magnetization of a spin with S=1 such as deuterium in the presence of a radio-frequency field under magic angle spinning (MAS) is described in terms of adiabatic modulations of the energy levels. In a brief initial period, part of the initial density operator nutates about the Hamiltonian and is dephased. The remaining spin-locked state undergoes persistent oscillatory transfer processes between various coherences with a periodicity given by the rotation of the sample. While all crystallites in the powder undergo such periodic transfer processes, the phases of the oscillations depend on the angle gamma of the crystallites. The angle gamma is the azimuthal angle defining the orientation of the unique axis of the quadrupolar interaction tensor in a rotor-fixed frame. The theory is extended to describe cross-polarization between spins S=1 and I=12 under MAS. There are four distinct Hartmann-Hahn matching conditions that correspond to four zero-quantum matching conditions, all of which are shifted and broadened compared to their spin S=12 counterparts. These matching conditions are further split into a family of sideband conditions separated by the spinning frequency. The theory allows the calculation of both shifts and broadening factors of the matching conditions, as verified by simulations and experiments.

  12. Perfect spin filtering effect in ultrasmall helical zigzag graphene nanoribbons

    Science.gov (United States)

    Zhang, Zi-Yue

    2017-02-01

    The spin-polarized transport properties of helical zigzag graphene nanoribbons (ZGNRs) are investigated by first-principles calculations. It is found that although all helical ZGNRs have similar density of states and edge states, they show obviously different transport characteristics depending on the curling manners. ZGNRs curled along zigzag orientation exhibit perfect spin filtering effect with a large spin-split gap near the Fermi level, while ZGNRs curled along armchair orientation behave as conventional conductors for both two spin channels. The spin filtering effect will be weakened with the increase of either ribbon width or curling diameter. The results suggest that ultrasmall helical ZGNRs have important potential applications in spintronics and flexible electronics.

  13. Observation of the Spin Hall Effect in Semiconductors

    Science.gov (United States)

    Kato, Y. K.; Myers, R. C.; Gossard, A. C.; Awschalom, D. D.

    2004-12-01

    Electrically induced electron-spin polarization near the edges of a semiconductor channel was detected and imaged with the use of Kerr rotation microscopy. The polarization is out-of-plane and has opposite sign for the two edges, consistent with the predictions of the spin Hall effect. Measurements of unstrained gallium arsenide and strained indium gallium arsenide samples reveal that strain modifies spin accumulation at zero magnetic field. A weak dependence on crystal orientation for the strained samples suggests that the mechanism is the extrinsic spin Hall effect.

  14. Spin transport in undoped InGaAs/AlGaAs multiple quantum well studied via spin photocurrent excited by circularly polarized light.

    Science.gov (United States)

    Zhu, Laipan; Liu, Yu; Huang, Wei; Qin, Xudong; Li, Yuan; Wu, Qing; Chen, Yonghai

    2016-12-01

    The spin diffusion and drift at different excitation wavelengths and different temperatures have been studied in undoped InGaAs/AlGaAs multiple quantum well (MQW). The spin polarization was created by optical spin orientation using circularly polarized light, and the reciprocal spin Hall effect was employed to measure the spin polarization current. We measured the ratio of the spin diffusion coefficient to the mobility of spin-polarized carriers. From the wavelength dependence of the ratio, we found that the spin diffusion and drift of holes became as important as electrons in this undoped MQW, and the ratio for light holes was much smaller than that for heavy holes at room temperature. From the temperature dependence of the ratio, the correction factors for the common Einstein relationship for spin-polarized electrons and heavy holes were firstly obtained to be 93 and 286, respectively.

  15. Club Orientation

    CERN Multimedia

    Club d'orientation

    2014-01-01

      COURSE ORIENTATION   Pas moins de 100 concurrents sont venus s’affronter sur les parcours proposés par le club d’orientation du CERN ce samedi 26 avril lors de la 4e étape de la coupe genevoise de printemps. Les podiums ont été attribués à :  Technique long avec 19 postes : 1er Yvan Balliot, ASO Annecy en 1:01:39 ; 2e Dominique Fleurent, ASO Annecy, en 1:05:12 ; 3e Rémi Fournier, SOS Sallanches, en 1:05:40. Technique moyen avec 14 postes : 1er Jean-Bernard Zosso, CO CERN, en 46:42 ; 2e Céline Zosso, CO CERN, en 50:51 ; 3e Clément Poncet, O’Jura Prémanon, en 51:27. Technique court avec 13 postes : 1er Jaakko Murtomaki, YKV Seinaejoki, en 36:04 ; 2e Marc Baumgartner en 41:27 ; 3e Natalia Niggli, O’Jura Prémanon, en 52:43. Sur les parcours facile moyen et facile court, victoire respectivement de Stéphanie...

  16. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

     Course d’orientation C’est sous un magnifique soleil que s’est tenue la 7e épreuve de la coupe genevoise organisée par le club d’orientation du CERN. Les organisateurs avaient concocté des parcours assez techniques sur le site de La Faucille. Sur le parcours technique long, beau podium avec la victoire de Domenico Lepori (double médaillés aux championnats du monde en 2010 en vétéran) du club Care Vevey en 1:00:23, juste devant Jürg Niggli du club O’Jura en 1:00:56 puis Beat Mueller du club Lausanne-Jorat en 1:04:28. Sur le parcours technique moyen, Franck Longchampt s’est octroyé la première place, sur le parcours technique court, le jeune Julien Vuitton, qui n’a pas tout à fait 11 ans, a remporté son circuit. Coté parcours facile moyen, Victor Kuznetsov a une fois de plus gagn&eacut...

  17. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2013-01-01

    Course d’orientation Face aux Championnats de France des Clubs à Poitiers, et à une météo hivernale (vent glaciale et pluie), il ne restait qu’une cinquantaine d’orienteurs pour participer à l’épreuve organisée le samedi 25 mai à Grange-Malval. Les participants ont tout de même bien apprécié les 5 circuits proposés par le Satus Genève. Les résultats sont disponibles sur notre site http://cern.ch/club-orientation. En plus des résultats, vous pourrez noter des informations sur la nouvelle école de CO encadrée par B. Barge, Prof. EPS à Ferney-Voltaire pour les jeunes à partir de 6 ans. La prochaine étape de la coupe genevoise se déroulera samedi 1er juin à Morez (39). Epreuve organisée par le club O’Jura&nb...

  18. Orienteering club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    Course d’orientation : Coupe Genevoise de printemps 2010 Et c’est reparti pour une nouvelle saison! Pour cette coupe de printemps 2010, le Club d’Orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose le calendrier suivant: – samedi 20 mars : Cossonay (Vd) – samedi 10 avril : Echallens (Vd) – samedi 17 avril : Trélex (Vd) – samedi 24 avril : Genolier (Vd) – samedi 1 mai : Vulbens/Valleiry (74) – samedi 8 mai : Bois de la Rippe (Vd) – samedi 29 mai : Sauvabellin (Vd) : relais – samedi 5 juin: St Cergue (Vd) : grande finale Les courses populaires ont lieu en général le samedi après-midi, elles sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Pour cela, divers types de parcours sont &agr...

  19. Orienteering club

    CERN Multimedia

    Club d’Orientation du CERN

    2015-01-01

    Courses d’orientation Nouvelle saison nouveau programme Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose une dizaine de courses populaires comptant pour la coupe Genevoise de printemps: samedi 28 mars: Vernand Dessus samedi 18 avril: Pougny/Challex samedi 25 avril: Chancy/Valleiry samedi 2 mai: Mauvernay samedi 9 mai: Longchaumois samedi 16 mai: Genolier samedi 30 mai: Prevondavaux samedi 6 juin: Biere-Ballens samedi 13 juin: Haut-Jura samedi 20 juin: Bonmont - Finale Ces courses sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Les inscriptions se font sur place le jour de l’épreuve. Si vous êtes débutant, vous pouvez profiter d’une initiation offerte par l’organisateur avant de vous lancer sur un parcours. Le club propose aussi...

  20. Orienteering club

    CERN Multimedia

    Orienteering Club

    2016-01-01

    Course d'orientation Calendrier des courses d’orientation Coupe genevoise d’automne 2016 Samedi 3 septembre : La Faucille (01) Samedi 10 septembre : Prémanon (39) Samedi 17 septembre : Saint-Cergue (VD) Samedi 24 septembre : Jorat / Corcelles (VD) Samedi 1 octobre: Bière - Ballens (VD) -relais Vendredi 14 octobre : Parc Mon Repos (GE) - nocturne Samedi 15 octobre : Terrasse de Genève (74) Samedi 29 octobre : Bonmont (VD) Samedi 5 novembre : Pomier (74) – one-man-relay - Finale   Courses ouvertes à toutes et à tous, sportifs, familles, débutants ou confirmés, du CERN ou d’ailleurs. Cinq circuits disponibles, ceci va du facile court (2 km) adapté aux débutants et aux enfants jusqu’au parcours technique long de 6 km pour les chevronnés en passant par les parcours facile moyen (4&am...

  1. COURSE ORIENTATION

    CERN Multimedia

    Club d'orientation du CERN

    2015-01-01

      Les coureurs d’orientation de la région se sont donné rendez-vous samedi dernier dans les bois de Pougny/Challex lors de l’épreuve organisée par le club d’orientation du CERN. La carte proposée pour les 5 circuits offrait aussi bien un coté très technique avec un relief pentu qu’un coté avec de grandes zones plates à forêt claire. Le parcours technique long comportant 20 postes a été remporté par Beat Muller du COLJ Lausanne en 56:26 devançant Denis Komarov, CO CERN en 57:30 et Yvan Balliot, ASO Annecy en 57:46. Pour les autres circuits les résultats sont les suivants: Technique moyen (13 postes): 1er Joël Mathieu en 52:32 à une seconde du 2e Vladimir Kuznetsov, COLJ Lausanne-Jorat, 3e Jean-Bernard Zosso, CO CERN, en 54:01 Technique court (12 postes): 1er Lennart Jirden, ...

  2. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2017-01-01

    Calendrier des courses de la Coupe Genevoise – printemps 2017 Club d'orientation - Julien,  jeune membre du club. Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose une série de courses populaires, qui se dérouleront des deux côtés de la frontière franco-suisse, à savoir : Samedi 1 avril : Pougny/Challex (01) Samedi 8 avril: Ballens (VD) Samedi 22 avril: Apples (VD) Samedi 29 avril: Mont Mussy (01) Samedi 6 mai: Prémanon (39) Samedi 13 mai: Mont Mourex (01) Samedi 20 mai: Prévondavaux (VD) Samedi 10 juin: Chancy/Valleiry (74) Samedi 17 juin: Trélex - Finale (VD) Ces courses sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel. Les inscriptions sur un des 5 parcours proposés se font sur place le jour de...

  3. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    COURSE D’ORIENTATION La finale de la coupe de printemps Après avoir remporté le challenge club, samedi 29 juin lors du relais inter-club à Lausanne, le Club d’orientation du CERN organisait la dernière étape de la coupe genevoise de printemps samedi 5 juin à Saint-Cergue dans les bois de Monteret (Canton de Vaud). Plus de 100 participants se sont déplacés pour venir participer à la finale et découvrir une toute nouvelle carte dans une forêt vallonnée. Les résultats pour chaque circuit de cette étape sont : Technique long : 1. Jurg Niggli du club O’Jura, 2. Clément Poncet, 3. Oystein Midttun. Technique moyen : 1. Zoltan Trocsanyi CO CERN, 2. Christophe Ingold, 3. Christina Falga. Technique court : 1. Pierre-Andre Baum, CARE Vevey, 2. Emese Szunyog, 3. Solène Balay. Facile moyen : 1. Elisa P...

  4. Orienteering Club

    CERN Multimedia

    Le Club d’orientation du CERN

    2017-01-01

    Course orientation Les courses d’orientation comptant pour la coupe genevoise de printemps s’enchainent dans la région franco-suisse. Samedi dernier, une bonne centaine de coureurs se sont retrouvés au Mont Mourex où le club du CERN avait préparé la sixième épreuve. A l’issue de la course, les participants confirmaient l’exigence des circuits, à savoir la condition physique et le côté technique du traçage. Le parcours technique long comportant 20 postes a été remporté par Darrell High du Care Vevey en 1:22:38 devançant Beat Muller du COLJ Lausanne-Jorat en 1:25:25 et Alison High également du Care Vevey en 1:28:51. Le circuit technique moyen a été remporté par Christophe Vuitton du CO CERN et le circuit technique court par Claire-Lise Rouiller, CO CERN. Les trois pr...

  5. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2015-01-01

    Course orientation C’est au pied du Salève, proche du Golf de Bosset, que le club d’orientation du CERN (CO CERN) a organisé samedi 19 septembre une nouvelle épreuve comptant pour la Coupe Genevoise d’automne. La zone « des Terrasses de Genève » avait été cartographiée et mise en service l’année dernière. Les participants ont pu apprécier un terrain ludique avec beaucoup de microreliefs, de points d’eau et de gros rochers, le tout au milieu d’une forêt assez claire et agréable à courir. Sur le parcours technique long, le résultat a été très serré puisque Pierrick Merino du club d’Annecy a gagné avec seulement 9 secondes d’avance sur Gaëtan Vuitton (CO CERN) qui confiait avoir perdu beaucoup du te...

  6. Manipulating Spin-Orbit Interaction in Semiconductors

    Science.gov (United States)

    Kohda, Makoto; Bergsten, Tobias; Nitta, Junsaku

    2008-03-01

    Spin-orbit interaction (SOI), where the orbital motion of electrons is coupled with the orientation of electron spins, originates from a relativistic effect. Generally, in nonrelativistic momentum, p = \\hbar k≪ m0c, the SOI is negligible. However, in a semiconductor heterostructure, the small energy-band gap (Eg ≪ m0c2) and the electron wave modulated by the atomic core potential markedly enhance the SOI. Since the SOI acts as an effective magnetic field, it may offer novel functionalities for controlling the spin degree of freedom such as the electrical spin generation and the electrical control of the spin precession in a semiconductor heterojunction. Here, we review recent experimental studies on the manipulation of the SOI in a semiconductor two-dimensional electron gas. We first present a theoretical overview of the Rashba SOI, which lifts the spin degeneracy due to structural inversion asymmetry. We then present experimental results on the quantum well (QW) thickness dependences of the Rashba SOI in InP/InGaAs/InAlAs asymmetric QWs by analyzing the weak antilocalization. Finally, we show quantum interference effects due to the spin precession in a small array of mesoscopic InGaAs rings, which is an experimental demonstration of the time-reversal Aharonov-Casher effect and the electromagnetic dual to the Al’tshuler-Aronov-Spivak effect.

  7. 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 free-induct

  8. 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

  9. Effects of DC bias on magnetic performance of high grades grain-oriented silicon steels

    Science.gov (United States)

    Ma, Guang; Cheng, Ling; Lu, Licheng; Yang, Fuyao; Chen, Xin; Zhu, Chengzhi

    2017-03-01

    When high voltage direct current (HVDC) transmission adopting mono-polar ground return operation mode or unbalanced bipolar operation mode, the invasion of DC current into neutral point of alternating current (AC) transformer will cause core saturation, temperature increasing, and vibration acceleration. Based on the MPG-200D soft magnetic measurement system, the influence of DC bias on magnetic performance of 0.23 mm and 0.27 mm series (P1.7=0.70-1.05 W/kg, B8>1.89 T) grain-oriented (GO) silicon steels under condition of AC / DC hybrid excitation were systematically realized in this paper. For the high magnetic induction GO steels (core losses are the same), greater thickness can lead to stronger ability of resisting DC bias, and the reasons for it were analyzed. Finally, the magnetostriction and A-weighted magnetostriction velocity level of GO steel under DC biased magnetization were researched.

  10. Spin-polarized spin excitation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J, E-mail: lothseb@us.ibm.com, E-mail: heinrich@almaden.ibm.com [IBM Research Division, Almaden Research Center, San Jose, CA 95120 (United States)

    2010-12-15

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

  11. 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).

  12. Entangled spins and ghost-spins

    CERN Document Server

    Jatkar, Dileep P

    2016-01-01

    We study patterns of quantum entanglement in systems of spins and ghost-spins regarding them as simple quantum mechanical toy models for theories containing negative norm states. We define a single ghost-spin as in arXiv:1602.06505 [hep-th] as a 2-state spin variable with an indefinite inner product in the state space. We find that whenever the spin sector is disentangled from the ghost-spin sector (both of which could be entangled within themselves), the reduced density matrix obtained by tracing over all the ghost-spins gives rise to positive entanglement entropy for positive norm states, while negative norm states have an entanglement entropy with a negative real part and a constant imaginary part. However when the spins are entangled with the ghost-spins, there are new entanglement patterns in general. For systems where the number of ghost-spins is even, it is possible to find subsectors of the Hilbert space where positive norm states always lead to positive entanglement entropy after tracing over the gho...

  13. Antiferromagnetic Heisenberg Spin Chain of a Few Cold Atoms in a One-Dimensional Trap.

    Science.gov (United States)

    Murmann, S; Deuretzbacher, F; Zürn, G; Bjerlin, J; Reimann, S M; Santos, L; Lompe, T; Jochim, S

    2015-11-20

    We report on the deterministic preparation of antiferromagnetic Heisenberg spin chains consisting of up to four fermionic atoms in a one-dimensional trap. These chains are stabilized by strong repulsive interactions between the two spin components without the need for an external periodic potential. We independently characterize the spin configuration of the chains by measuring the spin orientation of the outermost particle in the trap and by projecting the spatial wave function of one spin component on single-particle trap levels. Our results are in good agreement with a spin-chain model for fermionized particles and with numerically exact diagonalizations of the full few-fermion system.

  14. 免钛夹单极梯度电凝法腹腔镜阑尾切除术120例临床体会%Clinical analysis of 120 cases of laparoscopic appendectomy using monopolar gradient electrocoagulation without clips

    Institute of Scientific and Technical Information of China (English)

    徐玉刚; 崔刚; 梁建伟; 杨光; 刘君

    2011-01-01

    Objective:To explore the security and surgical techniques of monopolar gradient electrocoagulation in laparoscopic appendectomy (LA) without clips. Methods:Clinical data of 120 patients who underwent LA with monopolar gradient electrocoagulation from 2009 to 2011 were retrospectively analyzed. Results:All of the 120 cases were treated successfully under laparoscopy without conversion to open surgery. Mean operation time was 45min ( range ,30-90min). Mean length of hospital stay was 4d (range,2-7d). No severe complications were found. Conclusions:The monopolar gradient electrocoagulation is a feasible and safe method with shorter operation time,less blood loss, and less hosptial cost. This procedure is worth popularization without titanium clips left.%目的:探讨腹腔镜阑尾切除术(laparoscopic appendectomy,LA)应用免钛夹单极梯度电凝法处理阑尾系膜的安全性和手术技巧.方法:回顾分析为120例患者应用免钛夹单极梯度电凝法行LA的临床资料.结果:120例手术均获成功,手术时间30~90min,平均45min.术后住院2~7d,平均4d,术后无出血、肠梗阻等并发症发生.结论:应用免钛夹梯度电凝法行LA安全可行,患者出血少,手术时间短,费用低,且无钛夹遗留,值得推广应用.

  15. 鼻内镜下吸引器联合单极电凝治疗鼻顶鼻中后部出血%Endoscopic Treatment of Epistaxis by Monopolar Electrocoagulation and Self-designed Suction Apparatus

    Institute of Scientific and Technical Information of China (English)

    卿箭

    2011-01-01

    [目的]探讨鼻内镜下自制吸引器联合单极电凝治疗鼻顶、中后部鼻出血的疗效.[方法]在鼻内镜引导下,探查63例鼻顶、中后部鼻出血患者的出血点.先自制吸引器,在鼻腔局部麻醉下进行,用单极靠近吸引器末端金属电凝止血.术后常规使用抗生素及止血药.随访并观察治疗效果.[结果] 63例患者均安全顺利完成手术,其中5例术后再出血,行第2次治疗成功.随访半年,均无再次鼻出血.[结论]鼻内镜联合单极电凝治疗鼻顶部、中后部出血方便、实用、有效,并发症少,并能避免盲目性.%[Objective] To explore the effect on treatment of nose bleeding by monopolar electrocoagulation and self-designed suction apparatus underEndoscopy. [Method] Under the guidance of the nasal endoscope, to find 63 cases of patients with bleeding nose bleeding, which locating on thenasal roof or postmedian of nasal cavity. All patients were cured by monopolar electrocoagulation and self-designed suction apparatus under localanesthesia. [Results] 63 cases all got safety and satisfactory results.no nose bleeding recurred with 6 months follow-up. [Conclusion] Under theguidance of endoscope, the monopolar electrocoagulation accompanied by self-designed suction apparatus was simple and effective method on treatmentof nose bleeding, especially at the portion of the nasal roof or postmedian of nasal cavity

  16. Anisotropic intrinsic spin Hall effect in quantum wires.

    Science.gov (United States)

    Cummings, A W; Akis, R; Ferry, D K

    2011-11-23

    We use numerical simulations to investigate the spin Hall effect in quantum wires in the presence of both Rashba and Dresselhaus spin-orbit coupling. We find that the intrinsic spin Hall effect is highly anisotropic with respect to the orientation of the wire, and that the nature of this anisotropy depends strongly on the electron density and the relative strengths of the Rashba and Dresselhaus spin-orbit couplings. In particular, at low densities, when only one subband of the quantum wire is occupied, the spin Hall effect is strongest for electron momentum along the [N110] axis, which is the opposite of what is expected for the purely 2D case. In addition, when more than one subband is occupied, the strength and anisotropy of the spin Hall effect can vary greatly over relatively small changes in electron density, which makes it difficult to predict which wire orientation will maximize the strength of the spin Hall effect. These results help to illuminate the role of quantum confinement in spin-orbit-coupled systems, and can serve as a guide for future experimental work on the use of quantum wires for spin-Hall-based spintronic applications.

  17. Orienteering club

    CERN Document Server

    Club d'orientation

    2011-01-01

    Reprise fin août Le Club d’orientation, en partenariat avec d’autres clubs de la région, vous propose une nouvelle série de courses pour cet automne. Le calendrier à retenir est le suivant : Samedi 27 août : Granges Malval (GE) – type classique Samedi 10 septembre : Lamoura (39) – type classique Samedi 17 septembre : La Dôle (F/VD) – type classique Samedi 24 septembre : Monteret (VD) – relais Samedi 8 octobre : Saint Cergue (VD) – type classique Vendredi 14 octobre : Les Evaux (GE) – nocturne Samedi 15 octobre : Grand Jorat (VD) – type classique Samedi 22 octobre : Pomier (74) – type classique Samedi 5 novembre : Echallens (VD) – type classique Samedi 12 novembre : CERN (GE) - sprint - Finale Généralement cinq circuits sont disponibles : ceci va du facile court (2 km) adapt&eacu...

  18. Orienting hypnosis.

    Science.gov (United States)

    Hope, Anna E; Sugarman, Laurence I

    2015-01-01

    This article presents a new frame for understanding hypnosis and its clinical applications. Despite great potential to transform health and care, hypnosis research and clinical integration is impaired in part by centuries of misrepresentation and ignorance about its demonstrated efficacy. The authors contend that advances in the field are primarily encumbered by the lack of distinct boundaries and definitions. Here, hypnosis, trance, and mind are all redefined and grounded in biological, neurological, and psychological phenomena. Solutions are proposed for boundary and language problems associated with hypnosis. The biological role of novelty stimulating an orienting response that, in turn, potentiates systemic plasticity forms the basis for trance. Hypnosis is merely the skill set that perpetuates and influences trance. This formulation meshes with many aspects of Milton Erickson's legacy and Ernest Rossi's recent theory of mind and health. Implications of this hypothesis for clinical skills, professional training, and research are discussed.

  19. Spin Parity effects in STM single magnetic atom manipulation

    Science.gov (United States)

    Delgado, Fernando; Fernández-Rossier, Joaquín

    2012-02-01

    Recent experimental work shows that a spin polarized scanning tunneling microscopy tip can be used both to read and write the spin orientation of a single magnetic spin [1]. Inelastic electron tunneling spectroscopy (IETS) shows that spin of the magnetic atom is quantized [2], like the spin of a molecular magnet. Here we discuss two fundamental problems that arise when a bit of classical information is stored on a quantized spin: quantum spin tunneling and back-action of the readout process. Quantum tunneling is responsible of the loss of information due to the relaxation of the spin coupled to the environment, while the detection induced back-action leads to an unwanted modification of the spin state. We find that fundamental differences exist between integer and semi-integer spins when it comes to both, read and write classical information in a quantized spin.[4pt] [1] S. Loth et al, Nature Physics 6, 340 (2010).[0pt] [2] C. Hirjibehedin et al, Science 317, 1199 (2007).

  20. Spin-dependent recombination and hyperfine interaction at deep defects

    Science.gov (United States)

    Ivchenko, E. L.; Bakaleinikov, L. A.; Kalevich, V. K.

    2015-05-01

    We present a theoretical study of optical electron-spin orientation and spin-dependent Shockley-Read-Hall recombination in the longitudinal magnetic field, taking into account the hyperfine coupling between the bound-electron spin and the nuclear spin of a deep paramagnetic center. The master rate equations for the coupled system are extended to describe the nuclear spin relaxation by using two distinct relaxation times, τn 1 and τn 2, respectively, for defect states with one and two (singlet) bound electrons. The general theory is developed for an arbitrary value of the nuclear spin I . The magnetic-field and excitation-power dependencies of the electron and nuclear spin polarizations are calculated for the value of I =1 /2 . In this particular case the nuclear effects can be taken into account by a simple replacement of the bound-electron spin relaxation time by an effective time dependent on free-electron and hole densities and free-electron spin polarization. The role of nuclear spin relaxation is visualized by isolines of the electron spin polarization on a two-dimensional graph with the axes log2(τn 1) and log2(τn 2) .

  1. Fabrication of κ-Carrageenan Fibers by Wet Spinning: Spinning Parameters

    Directory of Open Access Journals (Sweden)

    Lingyan Kong

    2011-10-01

    Full Text Available This study demonstrates the fabrication of κ-carrageenan fibers by a wet-spinning method and discusses three important spinning parameters: coagulation bath composition, spinning rate and post-spinning mechanical drawing. The as-spun fiber diameter decreased with KCl and ethanol concentration in the coagulation bath. In general, the ultimate tensile stress and elongation at break both increased for KCl concentration from 0.1 to 0.5 M with and without ethanol, with no significant change above 0.5 M. Spinning rate affected the dope flow and thus the polymer orientation (apparent viscosity and fiber morphology. At spinning rates between 0.25 mL/min and 0.33 mL/min, the fiber diameter reached a minimum and the fiber surface was smooth. Both an increase and decrease from this spinning rate range increased the fiber diameter and roughness of the fiber surface. Post-spinning drawing of the fiber resulted in even smaller fiber diameter.

  2. Fabrication of κ-Carrageenan Fibers by Wet Spinning: Spinning Parameters.

    Science.gov (United States)

    Kong, Lingyan; Ziegler, Gregory R

    2011-10-11

    This study demonstrates the fabrication of κ-carrageenan fibers by a wet-spinning method and discusses three important spinning parameters: coagulation bath composition, spinning rate and post-spinning mechanical drawing. The as-spun fiber diameter decreased with KCl and ethanol concentration in the coagulation bath. In general, the ultimate tensile stress and elongation at break both increased for KCl concentration from 0.1 to 0.5 M with and without ethanol, with no significant change above 0.5 M. Spinning rate affected the dope flow and thus the polymer orientation (apparent viscosity) and fiber morphology. At spinning rates between 0.25 mL/min and 0.33 mL/min, the fiber diameter reached a minimum and the fiber surface was smooth. Both an increase and decrease from this spinning rate range increased the fiber diameter and roughness of the fiber surface. Post-spinning drawing of the fiber resulted in even smaller fiber diameter.

  3. Evaluation of the safety and effectiveness of monopolar hook during laparoscopic pelvic lymphadenectomy for gynecological cancer%单极电钩在腹腔镜盆腔淋巴结清扫术中的应用价值

    Institute of Scientific and Technical Information of China (English)

    张潍; 陈必良; 辛晓燕; 杨红; 刘淑娟; 蔡国青

    2013-01-01

    目的:评价单极电钩在腹腔镜盆腔淋巴结清扫术中的有效性、安全性.方法:设计开放、随机、配对、前瞻性实验,比较76例腹腔镜下妇科恶性肿瘤根治术患者单侧淋巴结清扫过程中出血量、淋巴结清扫数量、手术时间、术后髂窝引流量、10周后淋巴囊肿形成率及直径等数据.结果:单极电钩清扫盆腔淋巴结较之目前较流行的超声刀清扫过程,止血效果相当,但单侧淋巴结清扫数量(13.1±4.5个)、单侧手术时间(26.3±6.1min)、单侧淋巴囊肿形成率(11/76)明显优于后者.结论:合理应用单极电钩可完成腹腔镜盆腔淋巴结清扫,治疗效果强于超声刀,可降低腹腔镜手术费用.%Objective: In this prospective randomized pilot study, we evaluated the safety and effectiveness of monopolar hook during laparoscopic pelvic lymphadeneetomy for gynecological cancer,and compared to ultrasound knife. Methods: All 76 patients with gynecological cancer , who were suitable to perform laparoscopic lymphadeneetomy, were randomly assigned for lymphadeneetomy in one side of the pelvis using monopolar hook, whereas, the other side using ultrasound knife. Results: Compared with the ultrasound knife, monopolar hook had the same ability in hemosta-sis and cutting during the pelvic lymphadeneetomy, but, make a superior performance in single - side lymph nodes dis-section(13. 1 ±4.5 Vs 9.4 ±3.7 ,P <0.001) .operation time(26. 3 ±6. 1min Vs 39. 4 ±7.5min ,P = 0.003) and lymphocele formation rate (11/76 Vs 16/76, P < 0. 001). Conclusion: Laparoscopic pelvic lymphadeneetomy with monopolar hook is better than ultrasound knife and with decreased cost.

  4. 单双极电凝法行腹腔镜阑尾切除术的临床应用研究%The clinical practice research of the iaparoscopic appendectomy with the monopolar and bipolar electrocoagulation

    Institute of Scientific and Technical Information of China (English)

    杨富财; 李建忠; 任恒宽

    2011-01-01

    目的:研究应用单双极电凝法行腹腔镜阑尾切除术的可行性和安全性.方法:48例阑尾炎患者均采用单双极电凝法行腹腔镜阑尾切除术,用双极电凝和剪刀处理阑尾动脉和系膜,用单极电钩分离粘连并切开阑尾根部浆膜层,钛夹或缝线处理阑尾根部后切除阑尾.结果:48例手术均获成功,均无残端粪漏发生,亦无残端脓肿及其他并发症发生.术后平均住院3.5d,均痊愈出院.结论:用单双极电凝法行腹腔镜阑尾切除术安全、可行、经济实用,易在基层医院大力推广.%Objective:To study the feasibility and safety of the application of monopolar and bipolar electrocoagulation in the laparoscopic appendectomy (LA). Methods:Forty-eight patients who suffered from appendicitis underwent LA with the monopolar and bipolar electrocoagulation. Appendix artery and mesoappendix were treated with bipolar electrocoagulation and scissors, the adhesion and placenta percreta layer in the root of appendix was isolated and cut with monopolar electrical hook, the root of appendix was dealt with Titanium clip or suture before appendix was cut. Results:All operations were successfully performed,no complications such as stump fecal leakage or stump abscess occurred. The mean postoperative hospital stay was 3.5 d. Conclusions:The monopolar and bipolar electrocoagulation in LA is a workable,secure,economical and practical method,which is worth generalization in primary hospital.

  5. Simulation of Myelinated Nerve Conduction Block Induced by Electrical Stimulus of Monopolar and Bipolar Electrodes%不同电极电刺激对有髓神经传导阻断影响的仿真研究

    Institute of Scientific and Technical Information of China (English)

    孙晨; 张旭; 任朝晖; 董谦; 崔南

    2011-01-01

    目的 比较双电极双向脉冲刺激和单电极双向脉冲刺激在神经纤维传导阻断中的阻断阈值以及对神经纤维的损伤,并通过该研究为电刺激促进脊髓损伤后下尿路功能重建的动物实验选择最优的刺激模式.方法 以有限长单根有髓神经为研究对象,以两栖动物的有髓神经纤维FrankenhaeuserHuxley(F-H)模型为仿真研究基础.结果 比较了单、双电极在双向对称方波以及双向间歇方波作用下的阻断阈值以及单双电极在同样的刺激条件下(包括刺激波形、频率以及电流强度)产生的离子电流强度大小.结论 双电极的阻断阈值大于单电极的阻断阈值.在相同的刺激条件下,双电极双向脉冲刺激对神经的损伤程度小于单电极双向脉冲刺激.%To compare the thresholds and the degrees of axonal injury caused by the impulse stimulations of monopolar and bipolar electrodes in simulation study of nerve conduction block. This study aimed to find an optimal stimulus pattern for the animal experiment of restoring the normal function of lower urinary tract after spinal cord injury through electrical stimulation. We used the myelinated nerve fiber with limited length as the research object, and the Frankenhaeuser-Huxley ( F - H) model for mammal' s marrow nerve fiber as the basic system. We simulated the symmetry biphasic pulses and intermittent biphasic pulses to compare the block threshold and ionic current intensity generated by monopolar and bipolar electrodes. The simulating results indicated that the conduction block threshold induced by bipolar electrode is higher than that of monopolar electrode, and monopolar electrode caused greater damage to the axon when the other situations were same.

  6. [Role of rapid movement of spin labels in interpreting EPR spectra for spin-labelled macromolecules].

    Science.gov (United States)

    Nikol'skiĭ, D O; Timofeev, V P

    2003-01-01

    The method of spin labeling was used to monitor quick movements of side residues in protein monocrystals. The EPR spectra of monocrystals of spin-labeled lysozyme at different orientations of the tetrahonal crystal relative to the direction of the magnetic field were interpreted using the molecular dynamics method. A simple model was proposed, which enables one to calculate the trajectory of movements of the spin label by the molecular dynamic method over a relatively short period of time. The entire "frozen" protein molecule and a "defrozen" spin-labeled amino acid residue were considered in the framework of the model. To calculate the trajectories in vacuum, a model of spin-labeled lysozyme was constructed, and the parameters of force potentials for the atoms of the protein molecule and the spin label were specified. It follows from the calculations that the protein environment sterically hinders the range of eventual angular reorientations of the reporter NO-group of nitroxyl incorporated into the spin label, thereby affecting the shape of the EPR spectrum. However, the scatter in the positions of the reporter group in the angular space turned out to correspond to the Gauss distribution. Using the atomic coordinates of the spin label, obtained in a chosen time interval by the method of molecular dynamics, and taking into account the distribution of the states of the spin label in the ensemble of spin-labeled macromolecules in the crystal, we simulated the EPR spectra of monocrystals of spin-labeled lysozyme. The theoretical EPR spectra coincide well with the experimental.

  7. Spin Rotation of Formalism for Spin Tracking

    Energy Technology Data Exchange (ETDEWEB)

    Luccio,A.

    2008-02-01

    The problem of which coefficients are adequate to correctly represent the spin rotation in vector spin tracking for polarized proton and deuteron beams in synchrotrons is here re-examined in the light of recent discussions. The main aim of this note is to show where some previous erroneous results originated and how to code spin rotation in a tracking code. Some analysis of a recent experiment is presented that confirm the correctness of the assumptions.

  8. Nonlinear Giant Magnetoresistance in Dual Spin Valves

    Science.gov (United States)

    Aziz, A.; Wessely, O. P.; Ali, M.; Edwards, D. M.; Marrows, C. H.; Hickey, B. J.; Blamire, M. G.

    2009-12-01

    Giant magnetoresistance (GMR) arises from differential scattering of the majority and minority spin electrons by a ferromagnet (FM) so that the resistance of a heterostructure depends on the relative magnetic orientation of the FM layers within it separated by nonmagnetic spacers. Here, we show that highly nonequilibrium spin accumulation in metallic heterostructures results in a current-dependent nonlinear GMR which is not predicted within the present understanding of GMR. The behavior can be explained by allowing the scattering asymmetries in an ultrathin FM layer to be current dependent.

  9. Superdirected Beam of the Surface Spin Wave

    CERN Document Server

    Annenkov, Alexander Yu; Lock, Edwin H

    2016-01-01

    Visualized diffraction patterns of the surface spin wave excited by arbitrarily oriented linear transducer in tangentially magnetized ferrite film are investigated experimentally in the plane of ferrite film for the case where the transducer length D is much larger than the wavelength L. Superdirected (nonexpanding) beam of the surface spin wave with noncollinear wave vector k and group velocity vector V was observed experimentally: the angular width of this beam was about zero, the smearing of the beam energy along the film plane was minimal and the length of the beam trajectory was maximal (50 mm). Thus it was shown that such phenomenon as superdirected propagation of the wave exists in the nature.

  10. Cooper pairs spintronics in triplet spin valves.

    Science.gov (United States)

    Romeo, F; Citro, R

    2013-11-27

    We study a spin valve with a triplet superconductor spacer intercalated between two ferromagnets with noncollinear magnetizations. We show that the magnetoresistance of the triplet spin valve depends on the relative orientations of the d vector, characterizing the superconducting order parameter, and the magnetization directions of the ferromagnetic layers. For devices characterized by a long superconductor, the effects of a polarized current sustained by Cooper pairs only are observed. In this regime, a supermagnetoresistance effect emerges, and the chiral symmetry of the order parameter of the superconducting spacer is easily recognized. Our findings open new perspectives in designing spintronics devices based on the cooperation of ferromagnetic and triplet correlations.

  11. 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.

  12. 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.

  13. Rashba-type spin splitting and spin interference of the Cu(1 1 1) surface state at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dil, J. Hugo, E-mail: hugo.dil@epfl.ch [Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Meier, Fabian [Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Osterwalder, Jürg [Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)

    2015-05-15

    We report on the measurement of the Rashba-type spin splitting of the Shockley surface state on Cu(1 1 1) by spin- and angle-resolved photoemission at room temperature. Along the spatial direction expected for a Rashba-type effect the measured spin splitting corresponds to what has previously been reported by first principle calculations which were verified by high resolution ARPES using low temperatures and perfect crystals. Furthermore it is found that structural defects cause a spin-interference in the photoemission process and as a result the main measured spin signal is in the plane orthogonal to the typical Rashba orientation. Although the determination of the exact origin of this signal requires further investigations, the main results can be used as a benchmark for future spin-resolved photoemission set-ups.

  14. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2011-01-01

    Coupe genevoise, suite Résultats de la course de Saint-Cergue, sur la carte Les Pralies, samedi 17 septembre. Nouvelle victoire du finlandais Ville Keskisaari, du club COLJ sur le parcours technique long avec une belle avance sur le deuxième concurrent Christophe Vuitton du CO CERN. David Cuenin a remporté le parcours technique moyen, Franck Lonchampt du club O’Jura a, lui aussi, remporté à nouveau le parcours technique court, tout comme Julien Vuitton du club CO CERN sur le facile moyen. Pour finir, Stéphane Clément devance Victor Dannecker sur le parcours facile court. Les résultats complets sont disponibles sur le site du club du CERN http://cern.ch/club-orientation. Un abonnement est pris sur le secteur de Saint-Cergue, puisque le club organise les deux prochaines étapes de la coupe genevoise dans le Haut-Jura suisse. Tout d’abord le samedi 24 septembre, un relais inter-club se courr...

  15. Orienteering club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    COURSE D’ORIENTATION  De La Rippe à Sauvabellin, la coupe genevoise continue ! Le rendez-vous était donné samedi 8 mai aux amateurs de course d’orientation dans les bois de La Rippe (Canton de Vaud). Cette 6e épreuve était organisée par le Club Satus Grutli de Genève. Il est dommage que les participants n’aient pas été aussi nombreux que lors des dernières courses, les Championnats de France des clubs à Dijon ayant certainement retenus plus d’un compétiteur. La première place est revenue à : – Technique long : Berni Wehrle – Technique moyen : Jean-Bernard Zosso – Technique court : Berni Wehrle – Facile moyen : Peter Troscanyi – Facile court : Claire Droz. Il ne restera plus que deux épreuves ...

  16. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

    Course d'orientation Ces deux dernières semaines, le club a organisé la troisième puis la quatrième étape de la coupe de printemps, une dans la forêt de Collogny/Moissey près de Vulbens, l’autre vers le parcours vita de Trélex. Les résultats sont: Facile court Vulbens : 1er Léo Lonchampt, O’Jura (16:04), 2e Timothée Bazin (23:07), 3e Francesco Pieri (26:57) Trélex : 1er Noora Maurent (23:11), 2e Sarah Stuber, COLJ (26:51), 3e T. Bazin (28:17) Facile moyen Vulbens : 1er Victor Kuznetsov, CO CERN (25:36), 2e Didier Descourvières (28:03), 3e Konstantinos Haider, CO CERN (36:53) Trélex : 1er V. Kuznetsov, COLJ (38:01), 2e K. Haider, CO CERN (43:15), 3e ex aequo Olivia Nguyen et Sven Vietmeier (58:11) Technique court Vulbens : 1er Benoit Bazin (41:21), 2e Colas Gintzburger (55:12), 3e Nathan Freydoz (55:48) Trélex : 1...

  17. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2011-01-01

    Course d'orientation Avec la CO en nocturne organisée par le club du CERN vendredi 14 octobre au stade des Eveaux (Ge), et la CO à Savigny (Vd) proposée par le club de Lausanne-Jorat le lendemain, les étapes de la coupe genevoise d’automne s’enchainent rapidement. Il ne reste plus que 3 rendez-vous pour boucler la saison. Les premières places devraient certainement se jouer entre des membres du club du CERN, du O’Jura ou de Lausanne-Jorat. La prochaine course du club est programmée pour samedi 22 octobre à Pomier, près de Cruseilles. L’accueil se fera à partir de 12h30 et les départs s’échelonneront de 13h à 15h. * * * * * * * Nouvelle belle victoire samedi 8 octobre à Saint Cergue du jeune finlandais Ville Keskisaari (COLJ) en 50:56 devant Jürg Niggli (O’Jura) en 1:03:32, et Alexandre...

  18. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Course d'orientation Finale de la coupe genevoise Rapide et méthodique, voilà les qualités dont il fallait faire preuve pour remporter la dernière étape de la coupe organisée par le club du CERN dans les bois de Monteret. Il s’agissait d’une course au score où chaque concurrent disposait d’un temps imparti pour poinçonner le maximum de balises. Le parcours technique a été remporté par Tomas Shellman et le parcours facile par Victor Dannecker. Cette dernière étape était aussi décisive pour la désignation des lauréats de la coupe genevoise de printemps. Les résultats officiels étaient donnés par le président du club, L. Jirden : Circuit Technique Long : Berni Wehrle, Bruno Barge, Edvins Reisons Circuit Technique Moyen : J.-Bernard Zosso, ...

  19. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    De jour comme de nuit Les amateurs de course d’orientation ont pu s’en donner à cœur joie ce week-end puisqu’ils avaient la possibilité de courir sur deux épreuves en moins de 24 heures. En effet, le club du CERN organisait une course de nuit aux Evaux et la 7e étape de la coupe genevoise se tenait samedi après-midi dans les bois du Grand Jorat à Savigny. Les vainqueurs pour chaque course sont : Technique long CO de nuit: Julien Charlemagne, SOS Sallanches CO samedi: Philipp Khlebnikov, ANCO   Technique moyen CO de nuit: Céline Zosso, CO CERN CO samedi: Pavel Khlebnikov, ANCO Technique court CO de nuit: Colas Ginztburger, SOS Sallanches CO samedi: Victor Kuznetsov, COLJ Lausannne Facile moyen CO de nuit: Gaëtan Rickenbacher, CO CERN CO samedi: Tamas Szoke   Facile court CO de nuit:Oriane Rickenbacher, CO CERN CO samedi: Katya Kuznetsov...

  20. Orienteering club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    Course d'orientation Finale de la coupe d’automne La dernière épreuve de la coupe d’automne organisée par le club s’est déroulée ce samedi 1er novembre avec une course type «one-man-relay» dans la forêt de Trelex (Vd). Les concurrents des circuits techniques devaient parcourir trois boucles et ceux des circuits «faciles» deux boucles, avec changements de carte. Le parcours technique long a été remporté par un membre du club, Berni Wehrle. A l’issue de cette course, le Président du club, L. Jirden annonçait le classement général de la coupe d’automne, basé sur les 6 meilleurs résultats de la saison : Circuit technique long : 1er Juerg Niggli (O’Jura), 2e Berni Wehrle, 3e Beat Mueller. Circuit technique moyen : 1er Laurent Merat (O&r...

  1. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2012-01-01

    Finale de la coupe d’automne   La coupe d’automne organisée par le club d’orientation du CERN s’est terminée ce samedi 10 novembre avec une course sprint à Prévessins. C’était la 12e épreuve de la saison. En stage dans la région, Tanya Ryabkina, championne d’Europe en titre et médaillée de bronze en moyenne distance lors des championnats du monde à La Givrine cet été, a fait l’honneur de sa présence et termine 2e à 8 secondes de Trygve Buanes, norvégien du club de Bergen. A l’issue de cette dernière épreuve, le classement général de la coupe d’automne, basé sur les 8 meilleurs résultats de la saison, est ainsi le suivant : Circuit technique long : 1er Jurg Niggli (O&rsqu...

  2. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Finale de la coupe d’automne La dernière épreuve de la coupe d’automne organisée par le club d’orientation du CERN s’est déroulée ce samedi 2 novembre avec une course au score dans le bois Tollot (GE). Les concurrents disposaient d’un temps imparti pour poinçonner le maximum de balises différemment placées selon le circuit choisi. Juerg Niggli (club O’Jura) a remporté le parcours technique long. A l’issue de cette course, le classement général de la coupe d’automne, basé sur les 6 meilleurs résultats de la saison, est le suivant : Circuit technique long : 1er Juerg Niggli (O’Jura), 2e Bruno Barge, 3e Beat Mueller. Circuit technique moyen : 1er Laurent Merat (O’Jura), 2e Jirden Lennart, 3e Daria Niggli. Circuit technique court : 1er Victor Kuznetsov (COLJ), 2e N...

  3. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Course d'orientation Vers les dernières courses de printemps Une centaine de coureurs se sont déplacés sur le site de la Roche Fendue prés de Morez pour gouter à un des 5 parcours proposés par le club du O’Jura. Le terrain était gras mais que peut-on trouver d’autre avec cette météo! Les vainqueurs de chaque circuit sont : Alina Niggli (O’Jura) facile court, Natalja Niggli (O’Jura) facile moyen, Victor Kuznetsov (COLJ) technique court, Yves Rousselot (Balise 25) technique moyen et pour finir François Gonon (O’Jura) avec une victoire haut la main sur le technique long. Il ne reste plus que deux épreuves pour la coupe genevoise de printemps : à savoir samedi 8 juin, course de type longue distance organisée par le club de Lausanne Jorat (COLJ) dans le bois de Seyte sur Mutrux/Concise, inscription de 12h &...

  4. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Course d'orientation Le coup d’envoi de la coupe genevoise a été donné samedi 31 août dans les bois de Combe Froide à Prémanon. Plus de 150 coureurs avaient fait le déplacement. Les parcours facile court, facile moyen et technique court ont été remportés par des coureurs du club O’Jura - Ulysse Dannecker, Léo Lonchampt, Franck Lonchampt, le technique moyen par Pekka Marti du club Ol Biel Seeland et le technique long par Térence Risse du CA Rosé – également membre de l’équipe nationale suisse des moins de 20 ans. Pour le club du CERN, les meilleures résultats ont été obtenus pas Emese Szunyog sur technique court et Marie Vuitton sur technique moyen avec une 4e place. La prochaine course aura lieu samedi 14 septembre à La Faucille. Le club propose aussi...

  5. Orienteering Club

    CERN Multimedia

    CLUB D'ORIENTATION

    2013-01-01

    Calendrier de la coupe d’automne Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose, pour cette nouvelle coupe d’automne genevoise, une série de 10 courses. Le club du O’Jura donnera le coup d’envoi le samedi 31 août. Les courses s’enchaîneront selon le calendrier suivant : Samedi 31 août : Prémanon (39) - longue distance Samedi 14 septembre : La Faucille (01) - longue distance Samedi 21 septembre : Saint Cergue (VD) - longue distance Samedi 28 septembre : Ballens (VD) - relais Samedi 5 octobre : La Pile (VD) - longue distance Vendredi 11 octobre : Les Evaux (GE) - nocturne Samedi 12 octobre : Grand Jorat, Savigny (VD) - longue distance Samedi 19 octobre : Terrasses de Genève (74) - longue distance Samedi 26 octobre : Prémanon (39) - longue distance Samedi 2 novembre : Bois Tollot (GE) - score - Finale Les &a...

  6. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

    Relais inter-club/Challenge Carlo Milan Samedi dernier, lors de l’épreuve de course d’orientation organisée par le club du O’Jura, le moteur de la discipline était l’esprit d’équipe, puisqu’il était question d’un relais inter-club avec le Challenge Carlo Milan. Les clubs avaient aligné leurs coureurs soit sur le relais technique (trois participants) soit sur le relais facile (deux participants). Côté O’Jura, il fallait noter la participation de François Gonon, champion du monde 2011, côté club du CERN, Marie et Gaëtan Vuitton, jeunes espoirs du club, devaient préparer la piste pour lancer le dernier relayeur. Côté Lausanne-Jorat, il fallait compter sur le très jeune Viktor Kuznetsov. Les 31 équipes engagées n’ont pas m&ea...

  7. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

     Finale de la coupe de printemps   La dernière course d’orientation comptant pour la Coupe de printemps a eu lieu samedi dernier dans le village des Rousses et vers le Fort. Il s’agissait d’un sprint organisé par le club O’Jura. Les temps de course ont avoisiné les 20 minutes que ce soit pour le parcours technique moyen ou technique long. Tous les habitués étaient au rendez-vous pour venir consolider ou améliorer leur place au classement. A l’issue de cette course, le classement général de la Coupe de printemps prenant en compte les 6 meilleurs résultats des 9 courses était établi et les lauréats de chaque catégorie sont les suivants: Circuit technique long : 1er Berni Wehrle, 2e Bruno Barge, 3e Edvins Reisons. Circuit technique moyen : 1er Jean-Bernard Zosso, 2e Cédric Wehrl&...

  8. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2015-01-01

    Course orientation Finale de la coupe genevoise La série des courses de printemps s’est achevée samedi dernier dans les bois de Bonmont (Vaud) avec une épreuve «one-man-relay» organisée par le club. Le vainqueur du parcours technique  long, Yann Locatelli (Club de Chambéry Savoie) a réalisé les deux boucles comportant 24 balises avec presque 6 minutes d’avance sur le second concurrent Domenico Lepori (Club CARE Vevey). Cette dernière étape était aussi décisive pour la désignation des lauréats de la coupe genevoise de printemps, en comptabilisant les 6 meilleurs résultats sur les 10 épreuves. Le podium officiel était donné par le président du club, L. Jirden, qui profitait de l’occasion pour remercier tous les participants et également tous les...

  9. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation Samedi 20 avril, les organisateurs du Club de CO du CERN ont accueilli au Mont Mourex 70 participants qui n’ont pas hésité à venir malgré la forte bise. Berni Wehrle du CO CERN s’est octroyé la première place en 1:04:49 sur le parcours technique long devant Pyry Kettunen du Saynso Juankoski en 1:06:52, la 3e place revenant à Bruno Barge, CO CERN, à 7 secondes. Les autres parcours ont été remportés par : Technique moyen : 1er Jacques Moisset, Chamonix (47:44), 2e Yves Rousselot, Balise 25 Besançon (57:16), 3e Jean-Bernard Zosso, CO CERN (59:28). Technique court : 1er Victor Kuznetsov, COLJ (51:53), 2e Pierrick Collet, CO CERN (1:12:52), 3e Dominique Balay, CO CERN (1:16:04). Pour les parcours facile moyen et facile court, Ralf Nardini et Léa Nicolas, tous deux du CO CERN, terminaient respectivement premier. Voi...

  10. Orienteering club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    Course d'orientation C’est sous un beau soleil samedi 4 octobre que s’est déroulée la 6e étape de la Coupe genevoise d’automne organisée par le club. Plus d’une centaine de concurrents provenant de 7 clubs de CO avaient fait le déplacement pour courir sur un des cinq parcours proposés dans les bois de Trélex-Génolier (VD). Le podium est le suivant : Technique long (5,9 km, 19 postes) : 1er Jurg Niggli, O’Jura (1:00:02); 2e Berni Wehrle, CO CERN (1:06:44); 3e Konrad Ehrbar, COLJ (1:07:08) Technique moyen (4,8 km, 18 postes) : 1er Christophe Vuitton, CO CERN (54:25); 2e J.B. Zosso, CO CERN (1:01:19); 3e Jeremy Wichoud, COLJ (1:06:21) Technique court (3,8 km, 14 postes) : 1er Julien Vuitton, CO CERN (36:19); 2e Vladimir Kuznetsov, COLJ (48:47); 3e Natalia Niggli, O’Jura (50:38) Facile moyen (3,2 km, 11 postes) : 1ère Alina Niggli, O&...

  11. Spin-Dependent Transport through Chiral Molecules Studied by Spin-Dependent Electrochemistry

    Science.gov (United States)

    2016-01-01

    dark” measurements, we also describe photoelectrochemical measurements in which light is used to affect the spin selective electron transport through the chiral molecules. We describe how the excitation of a chromophore (such as CdSe nanoparticles), which is attached to a chiral working electrode, can flip the preferred spin orientation of the photocurrent, when measured under the identical conditions. Thus, chirality-induced spin polarization, when combined with light and magnetic field effects, opens new avenues for the study of the spin transport properties of chiral molecules and biomolecules and for creating new types of spintronic devices in which light and molecular chirality provide new functions and properties. PMID:27797176

  12. The effect of spin in swing bowling in cricket: model trajectories for spin alone

    Science.gov (United States)

    Robinson, Garry; Robinson, Ian

    2015-02-01

    In ‘swing’ bowling, as employed by fast and fast-medium bowlers in cricket, back-spin along the line of the seam is normally applied in order to keep the seam vertical and to provide stability against ‘wobble’ of the seam. Whilst spin is normally thought of as primarily being the slow bowler's domain, the spin applied by the swing bowler has the side-effect of generating a lift or Magnus force. This force, depending on the orientation of the seam and hence that of the back-spin, can have a side-ways component as well as the expected vertical ‘lift’ component. The effect of the spin itself, in influencing the trajectory of the fast bowler's delivery, is normally not considered, presumably being thought of as negligible. The purpose of this paper is to investigate, using calculated model trajectories, the amount of side-ways movement due to the spin and to see how this predicted movement compares with the total observed side-ways movement. The size of the vertical lift component is also estimated. It is found that, although the spin is an essential part of the successful swing bowler's delivery, the amount of side-ways movement due to the spin itself amounts to a few centimetres or so, and is therefore small, but perhaps not negligible, compared to the total amount of side-ways movement observed. The spin does, however, provide a considerable amount of lift compared to the equivalent delivery bowled without spin, altering the point of pitching by up to 3 m, a very large amount indeed. Thus, for example, bowling a ball with the seam pointing directly down the pitch and not designed to swing side-ways at all, but with the amount of back-spin varied, could provide a very powerful additional weapon in the fast bowler's arsenal. So-called ‘sling bowlers’, who use a very low arm action, can take advantage of spin since effectively they can apply side-spin to the ball, giving rise to a large side-ways movement, ˜ 20{}^\\circ cm or more, which certainly is

  13. Optical detection of spin-filter effect for electron spin polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Majee, S.; Lampel, G.; Lassailly, Y.; Paget, D.; Peretti, J. [Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique - CNRS, 91128 Palaiseau Cedex (France); Tereshchenko, O. E., E-mail: teresh@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2014-08-04

    We have monitored the cathodoluminescence (CL) emitted upon injection of free electrons into a hybrid structure consisting of a thin magnetic Fe layer deposited on a p-GaAs substrate, in which InGaAs quantum wells are embedded. Electrons transmitted through the unbiased metal/semiconductor junction recombine radiatively in the quantum wells. Because of the electron spin-filtering across the Fe/GaAs structure, the CL intensity, collected from the backside, is found to depend on the relative orientation between the injected electronic spin polarization and the Fe layer magnetization. The spin asymmetry of the CL intensity in such junction provides a compact optical method for measuring spin polarization of free electrons beams or of hot electrons in solid-state devices.

  14. Spin Transport by Collective Spin Excitations

    Science.gov (United States)

    Hammel, P. Chris

    We report studies of angular momentum transport in insulating materials. Our measurements reveal efficient spin pumping from high wavevector k spin waves in thin film Y3Fe5O12 (YIG): spin pumping is independent of wavevector up to k ~ 20 μm-1. Optical detection of YIG FMR by NV centers in diamond reveals a role for spin waves in this insulator-to-insulator spin transfer process. Spin transport is typically suppressed by insulating barriers, but we find that fluctuating antiferromagnetic correlations enable efficient spin transport at nm-scale thicknesses in insulating antiferromagnets, even in the absence of long-range order, and that the spin decay length increases with the strength of the antiferromagnetic correlations. This research is supported by the U.S. DOE through Grants DE-FG02-03ER46054 and DE-SC0001304, by the NSF MRSEC program through Grant No. 1420451 and by the Army Research Office through Grant W911NF0910147.

  15. Imaging Spin Dynamics on the Nanoscale using X-Ray Microscopy

    Directory of Open Access Journals (Sweden)

    Hermann eStoll

    2015-04-01

    Full Text Available The dynamics of emergent magnetic quasiparticles, such as vortices, domain walls, and bubbles are studied by scanning transmission x-ray microscopy (STXM, combining magnetic (XMCD contrast with about 25 nm lateral resolution as well as 70 ps time resolution. Essential progress in the understanding of magnetic vortex dynamics is achieved by vortex core reversal observed by sub-GHz excitation of the vortex gyromode, either by ac magnetic fields or spin transfer torque. The basic switching scheme for this vortex core reversal is the generation of a vortex-antivortex pair. Much faster vortex core reversal is obtained by exciting azimuthal spin wave modes with (multi-GHz rotating magnetic fields or orthogonal monopolar field pulses in x and y direction, down to 45 ps in duration. In that way unidirectional vortex core reversal to the vortex core 'down' or 'up' state only can be achieved with switching times well below 100 ps. Coupled modes of interacting vortices mimic crystal properties. The individual vortex oscillators determine the properties of the ensemble, where the gyrotropic mode represents the fundamental excitation. By self-organized state formation we investigate distinct vortex core polarization configurations and understand these eigenmodes in an extended Thiele model. Analogies with photonic crystals are drawn. Oersted fields and spin-polarized currents are used to excite the dynamics of domain walls and magnetic bubbles. From the measured phase and amplitude of the displacement of domain walls we deduce the size of the non-adiabatic spin-transfer torque. For sensing applications, the displacement of domain walls is studied and a direct correlation between domain wall velocity and spin structure is found. Finally the synchronous displacement of multiple domain walls using perpendicular field pulses is demonstrated as a possible paradigm shift for magnetic memory and logic applications.

  16. Imaging Spin Dynamics on the Nanoscale using X-Ray Microscopy

    Science.gov (United States)

    Stoll, Hermann; Noske, Matthias; Weigand, Markus; Richter, Kornel; Krüger, Benjamin; Reeve, Robert; Hänze, Max; Adolff, Christian; Stein, Falk-Ulrich; Meier, Guido; Kläui, Mathias; Schütz, Gisela

    2015-04-01

    The dynamics of emergent magnetic quasiparticles, such as vortices, domain walls, and bubbles are studied by scanning transmission x-ray microscopy (STXM), combining magnetic (XMCD) contrast with about 25 nm lateral resolution as well as 70 ps time resolution. Essential progress in the understanding of magnetic vortex dynamics is achieved by vortex core reversal observed by sub-GHz excitation of the vortex gyromode, either by ac magnetic fields or spin transfer torque. The basic switching scheme for this vortex core reversal is the generation of a vortex-antivortex pair. Much faster vortex core reversal is obtained by exciting azimuthal spin wave modes with (multi-GHz) rotating magnetic fields or orthogonal monopolar field pulses in x and y direction, down to 45 ps in duration. In that way unidirectional vortex core reversal to the vortex core 'down' or 'up' state only can be achieved with switching times well below 100 ps. Coupled modes of interacting vortices mimic crystal properties. The individual vortex oscillators determine the properties of the ensemble, where the gyrotropic mode represents the fundamental excitation. By self-organized state formation we investigate distinct vortex core polarization configurations and understand these eigenmodes in an extended Thiele model. Analogies with photonic crystals are drawn. Oersted fields and spin-polarized currents are used to excite the dynamics of domain walls and magnetic bubbles. From the measured phase and amplitude of the displacement of domain walls we deduce the size of the non-adiabatic spin-transfer torque. For sensing applications, the displacement of domain walls is studied and a direct correlation between domain wall velocity and spin structure is found. Finally the synchronous displacement of multiple domain walls using perpendicular field pulses is demonstrated as a possible paradigm shift for magnetic memory and logic applications.

  17. 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.

  18. Higher spin black holes

    National Research Council Canada - National Science Library

    Gutperle, Michael; Kraus, Per

    2011-01-01

    .... We find solutions that generalize the BTZ black hole and carry spin-3 charge. The black hole entropy formula yields a result for the asymptotic growth of the partition function at finite spin-3 chemical potential...

  19. Arbitrary Spin Galilean Oscillator

    CERN Document Server

    Hagen, C R

    2014-01-01

    The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be extended successfully to the arbitrary spin S case primarily because of the unwieldiness of general spin Lorentz invariant wave equations. It is shown here using the formalism of totally symmetric multispinors that the Dirac oscillator can, however, be made to accommodate spin by incorporating it into the framework of Galilean relativity. This is done explicitly for spin zero and spin one as special cases of the arbitrary spin result. For the general case it is shown that the coefficient of the spin-orbit term has a 1/S behavior by techniques which are virtually identical to those employed in the derivation of the g-factor carried out over four decades ago.

  20. NMR with generalized dynamics of spin and spatial coordinates

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Jae

    1987-11-01

    This work is concerned with theoretical and experimental aspects of the generalized dynamics of nuclear spin and spatial coordinates under magnetic-field pulses and mechanical motions. The main text begins with an introduction to the concept of ''fictitious'' interactions. A systematic method for constructing fictitious spin-1/2 operators is given. The interaction of spins with a quantized-field is described. The concept of the fictitious interactions under the irradiation of multiple pulses is utilized to design sequences for selectively averaging linear and bilinear operators. Relations between the low-field sequences and high-field iterative schemes are clarified. These relations and the transformation properties of the spin operators are exploited to develop schemes for heteronuclear decoupling of multi-level systems. The resulting schemes are evaluated for heteronuclear decoupling of a dilute spin-1/2 from a spin-1 in liquid crystal samples and from a homonuclear spin-1/2 pair in liquids. A relation between the spin and the spatial variables is discussed. The transformation properties of the spin operators are applied to spatial coordinates and utilized to develop methods for removing the orientational dependence responsible for line broadening in a powder sample. Elimination of the second order quadrupole effects, as well as the first order anisotropies is discussed. It is shown that various sources of line broadening can effectively be eliminated by spinning and/or hopping the sample about judiciously chosen axes along with appropriate radio-frequency pulse sequences.

  1. SPIN TILTS IN THE DOUBLE PULSAR REVEAL SUPERNOVA SPIN ANGULAR-MOMENTUM PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Farr, Will M.; Kremer, Kyle; Kalogera, Vassiliki [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lyutikov, Maxim, E-mail: w-farr@northwestern.edu, E-mail: kylekremer2012@u.northwestern.edu, E-mail: vicky@northwestern.edu, E-mail: lyutikov@purdue.edu [Physics Department, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)

    2011-12-01

    The system PSR J0737-3039 is the only binary pulsar known to consist of two radio pulsars (PSR J0737-3039 A and PSR J0737-3039 B). This unique configuration allows measurements of spin orientation for both pulsars: pulsar A's spin is tilted from the orbital angular momentum by no more than 14 deg at 95% confidence; pulsar B's by 130 {+-} 1 deg at 99.7% confidence. This spin-spin misalignment requires that the origin of most of B's present-day spin is connected to the supernova that formed pulsar B. Under the simplified assumption of a single, instantaneous kick during the supernova, the spin could be thought of as originating from the off-center nature of the kick, causing pulsar B to tumble to its misaligned state. With this assumption, and using current constraints on the kick magnitude, we find that pulsar B's instantaneous kick must have been displaced from the center of mass of the exploding star by at least 1 km and probably 5-10 km. Regardless of the details of the kick mechanism and the process that produced pulsar B's current spin, the measured spin-spin misalignment in the double pulsar system provides an empirical, direct constraint on the angular momentum production in this supernova. This constraint can be used to guide core-collapse simulations and the quest for understanding the spins and kicks of compact objects.

  2. Spin tune mapping as a novel tool to probe the spin dynamics in storage rings

    Directory of Open Access Journals (Sweden)

    2017-07-01

    Full Text Available Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called spin tune mapping, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 using polarized deuterons stored in the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than 2.8  μ  rad.

  3. Spinning Eggs and Ballerinas

    Science.gov (United States)

    Cross, Rod

    2013-01-01

    Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction…

  4. Spinning Eggs and Ballerinas

    Science.gov (United States)

    Cross, Rod

    2013-01-01

    Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction…

  5. A new effective-one-body Hamiltonian with next-to-leading order spin-spin coupling

    CERN Document Server

    Balmelli, Simone

    2015-01-01

    We present a new effective-one-body (EOB) Hamiltonian with next-to-leading order (NLO) spin-spin coupling for black hole binaries endowed with arbitrarily oriented spins. The Hamiltonian is based on the model for parallel spins and equatorial orbits developed in [Physical Review D 90, 044018 (2014)], but differs from it in several ways. In particular, the NLO spin-spin coupling is not incorporated by a redefinition of the centrifugal radius $r_c$, but by separately modifying certain sectors of the Hamiltonian, which are identified according to their dependence on the momentum vector. The gauge-fixing procedure we follow allows us to reduce the 25 different terms of the NLO spin-spin Hamiltonian in Arnowitt-Deser-Misner coordinates to only 9 EOB terms. This is an improvement with respect to the EOB model recently proposed in [Physical Review D 91, 064011 (2015)], where 12 EOB terms were involved. Another important advantage is the remarkably simple momentum structure of the spin-spin terms in the effective Ham...

  6. Analysis of spin transfer torque in Co/Cu/Co pseudo-spin-valve with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.s [Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Guo, Jie, E-mail: elegj@nus.edu.s [Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Tan, Seng Ghee, E-mail: TAN_Seng_Ghee@dsi.a-star.edu.s [Data Storage Institute, 5 Engineering Drive 1, (Off Kent Ridge Crescent), Singapore 117608 (Singapore)

    2009-05-01

    Perpendicular-magnetized pseudo-spin-valves (PSV) boast the advantages of lower aspect ratio, greater magnetic stability and thermal stability; and hence constitute a promising candidate for achieving higher integration area density. In this paper, we investigate the spin transport and spin transfer torque in a Co/Cu(1 1 1)/Co perpendicular PSV structure where the magnetization of the Co layers are oriented in the out-of-plane direction, in the presence of a spin-polarized current in the perpendicular-to-plane (CPP) geometry. Both ballistic spin-dependent transmission/reflection at the two Co-Cu interfaces and diffusive spin relaxation within the Co and Cu layers are considered in our model. The ballistic calculations predict an absorbed spin current component at the Cu-free Co interface, which constitutes the main source (approx90%) of the total spin transfer torque in the free Co layer. The remaining torque arises from the spin relaxation of transmitted spin current within the free Co layer. Our model predicts a lower range of the critical current density of less than 10{sup 7} A/cm{sup 2} for perpendicularly magnetized PSVs, while that for in-plane magnetized PSVs is of the order of several 10{sup 7} A/cm{sup 2}. Additionally, perpendicularly magnetized PSVs also possess other practical advantages which make them promising candidates for future MRAM applications.

  7. Production of Spin-Two Gauge Bosons

    OpenAIRE

    Konitopoulos, Spyros; Savvidy, George

    2008-01-01

    We considered spin-two gauge boson production in the fermion pair annihilation process and calculated the polarized cross sections for each set of helicity orientations of initial and final particles. The angular dependence of these cross sections is compared with the similar annihilation cross sections in QED with two photons in the final state, with two gluons in QCD and W-pair in Electroweak theory.

  8. Spin structure of electron subbands in (110)-grown quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Nestoklon, M. O.; Tarasenko, S. A. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Jancu, J.-M. [FOTON-INSA Laboratory, UMR 6082 au CNRS, INSA de Rennes, 35043 Rennes Cedex (France); Voisin, P. [CNRS-Laboratoire de Photonique et de Nanostructures, 91460 Marcoussis (France)

    2013-12-04

    We present the theory of fine structure of electron states in symmetric and asymmetric zinc-blende-type quantum wells with the (110) crystallographic orientation. By combining the symmetry analysis, sp{sup 3}d{sup 5}s* tight-binding method, and envelope-function approach we obtain quantitative description of in-plane wave vector, well width and applied electric field dependencies of the zero-magnetic-field spin splitting of electron subbands and extract spin-orbit-coupling parameters.

  9. Spin storage in quantum dot ensembles and single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Dominik

    2009-10-15

    This thesis deals with the investigation of spin relaxation of electrons and holes in small ensembles of self-assembled quantum dots using optical techniques. Furthermore, a method to detect the spin orientation in a single quantum dot was developed in the framework of this thesis. A spin storage device was used to optically generate oriented electron spins in small frequency selected quantum dot ensembles using circularly polarized optical excitation. The spin orientation can be determined by the polarization of the time delayed electroluminescence signal generated by the device after a continuously variable storage time. The degree of spin polarized initialization was found to be limited to 0.6 at high magnetic fields, where anisotropic effects are compensated. The spin relaxation was directly measured as a function of magnetic field, lattice temperature and s-shell transition energy of the quantum dot by varying the spin storage time up to 30 ms. Very long spin lifetimes are obtained with a lower limit of T{sub 1}=20 ms at B=4 T and T=1 K. A strong magnetic field dependence T{sub 1}{proportional_to}B{sup -5} has been observed for low temperatures of T=1 K which weakens as the temperature is increased. In addition, the temperature dependence has been determined with T{sub 1}{proportional_to}T{sup -1}. The characteristic dependencies on magnetic field and temperature lead to the identification of the spin relaxation mechanism, which is governed by spin-orbit coupling and mediated by single phonon scattering. This finding is qualitatively supported by the energy dependent measurements. The investigations were extended to a modified device design that enabled studying the spin relaxation dynamics of heavy holes in self-assembled quantum dots. The measurements show a polarization memory effect for holes with up to 0.1 degree of polarization. Furthermore, investigations of the time dynamics of the hole spin relaxation reveal surprisingly long lifetimes T{sub 1}{sup h

  10. Inverse spin Hall effect by spin injection

    Science.gov (United States)

    Liu, S. Y.; Horing, Norman J. M.; Lei, X. L.

    2007-09-01

    Motivated by a recent experiment [S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176 (2006)], the authors present a quantitative microscopic theory to investigate the inverse spin-Hall effect with spin injection into aluminum considering both intrinsic and extrinsic spin-orbit couplings using the orthogonalized-plane-wave method. Their theoretical results are in good agreement with the experimental data. It is also clear that the magnitude of the anomalous Hall resistivity is mainly due to contributions from extrinsic skew scattering.

  11. Spin supplementary conditions for spinning compact binaries

    CERN Document Server

    Mikóczi, Balázs

    2016-01-01

    We consider the different spin supplementary conditions (SSC) for a spinning compact binary with the leading-order spin-orbit (SO) interaction. The Lagrangian of the binary system can be constructed but it is acceleration-dependent in two cases of SSC. We rewrite the generalized Hamiltonian formalism proposed by Ostrogradsky and compute the conservative quantities and the dissipative part of relative motion during the gravitational radiation of each SSCs. We give the orbital elements and observed quantities of the SO dynamics, for instance the energy and the orbital angular momentum losses and waveforms and discuss their SSC dependence.

  12. Manipulation of Magnetic Insulators Using Spin Torque from the Spin Hall Effect

    Science.gov (United States)

    Jermain, Colin; Rosenberg, Aaron; Paik, Hanjong; Aradhya, Sriharsha; Wang, Hailong; Heron, John; Nowack, Katja; Kirtley, John; Schlom, Darrell; Moler, Kathryn; Yang, Fengyuan; Ralph, Dan

    2015-03-01

    We are exploring the possibility of current-induced switching driven by spin torque from the spin Hall effect for micron and nanoscale devices made from the magnetic insulators yttrium iron garnet (YIG) and lutetium iron garnet (LuIG). We will report on the fabrication of devices incorporating thin films of YIG or LuIG with thickness less than 20 nm and in-plane magnetization. We use electron beam lithography and ion milling to pattern the films into device structures with sizes ranging from 50 nm to 4 microns, integrated with a Ta or Pt layer so that we can use the spin Hall effect to apply spin-transfer torque to the magnetic materials. With scanning SQUID magnetometry we measure the in-plane dipole orientation of the device magnetic moment at 4 K. By examining the magnetic orientation as a function of applied current we investigate whether the spin Hall torque can be used to drive reliable magnetic switching at low current levels.

  13. Kagome spin ice

    Science.gov (United States)

    Mellado, Paula

    Spin ice in magnetic pyrochlore oxides is a peculiar magnetic state. Like ordinary water ice, these materials are in apparent violation with the third law of thermodynamics, which dictates that the entropy of a system in thermal equilibrium vanishes as its temperature approaches absolute zero. In ice, a "zero-point" entropy is retained down to low temperatures thanks to a high number of low-energy positions of hydrogen ions associated with the Bernal-Fowler ice-rules. Spins in pyrochlore oxides Ho2Ti 2O7 and Dy2Ti2O7 exhibit a similar degeneracy of ground states and thus also have a sizable zero-point entropy. A recent discovery of excitations carrying magnetic charges in pyrochlore spin ice adds another interesting dimension to these magnets. This thesis is devoted to a theoretical study of a two-dimensional version of spin ice whose spins reside on kagome, a lattice of corner-sharing triangles. It covers two aspects of this frustrated classical spin system: the dynamics of artificial spin ice in a network of magnetic nanowires and the thermodynamics of crystalline spin ice. Magnetization dynamics in artificial spin ice is mediated by the emission, propagation and absorption of domain walls in magnetic nanowires. The dynamics shows signs of self-organized behavior such as avalanches. The theoretical model compares favorably to recent experiments. The thermodynamics of the microscopic version of spin ice on kagome is examined through analytical calculations and numerical simulations. The results show that, in addition to the high-temperature paramagnetic phase and the low-temperature phase with magnetic order, spin ice on kagome may have an intermediate phase with fluctuating spins and ordered magnetic charges. This work is concluded with a calculation of the entropy of kagome spin ice at zero temperature when one of the sublattices is pinned by an applied magnetic field and the system breaks up into independent spin chains, a case of dimensional reduction.

  14. Symmetric Euler orientation representations for orientational averaging.

    Science.gov (United States)

    Mayerhöfer, Thomas G

    2005-09-01

    A new kind of orientation representation called symmetric Euler orientation representation (SEOR) is presented. It is based on a combination of the conventional Euler orientation representations (Euler angles) and Hamilton's quaternions. The properties of the SEORs concerning orientational averaging are explored and compared to those of averaging schemes that are based on conventional Euler orientation representations. To that aim, the reflectance of a hypothetical polycrystalline material with orthorhombic crystal symmetry was calculated. The calculation was carried out according to the average refractive index theory (ARIT [T.G. Mayerhöfer, Appl. Spectrosc. 56 (2002) 1194]). It is shown that the use of averaging schemes based on conventional Euler orientation representations leads to a dependence of the result from the specific Euler orientation representation that was utilized and from the initial position of the crystal. The latter problem can be overcome partly by the introduction of a weighing factor, but only for two-axes-type Euler orientation representations. In case of a numerical evaluation of the average, a residual difference remains also if a two-axes type Euler orientation representation is used despite of the utilization of a weighing factor. In contrast, this problem does not occur if a symmetric Euler orientation representation is used as a matter of principle, while the result of the averaging for both types of orientation representations converges with increasing number of orientations considered in the numerical evaluation. Additionally, the use of a weighing factor and/or non-equally spaced steps in the numerical evaluation of the average is not necessary. The symmetrical Euler orientation representations are therefore ideally suited for the use in orientational averaging procedures.

  15. Spinning particles and higher spin field equations

    CERN Document Server

    Bastianelli, Fiorenzo; Corradini, Olindo; Latini, Emanuele

    2015-01-01

    Relativistic particles with higher spin can be described in first quantization using actions with local supersymmetry on the worldline. First, we present a brief review of these actions and their use in first quantization. In a Dirac quantization scheme the field equations emerge as Dirac constraints on the Hilbert space, and we outline how they lead to the description of higher spin fields in terms of the more standard Fronsdal-Labastida equations. Then, we describe how these actions can be extended so that the propagating particle is allowed to take different values of the spin, i.e. carry a reducible representation of the Poincar\\'e group. This way one may identify a four dimensional model that carries the same degrees of freedom of the minimal Vasiliev's interacting higher spin field theory. Extensions to massive particles and to propagation on (A)dS spaces are also briefly commented upon.

  16. Spin-dependent delay time in ferromagnet/insulator/ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Xie, ZhengWei; Zheng Shi, De; Lv, HouXiang [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066, Sichuan (China)

    2014-07-07

    We study theoretically spin-dependent group delay and dwell time in ferromagnet/insulator/ferromagnet (FM/I/FM) heterostructure. The results indicate that, when the electrons with different spin orientations tunnel through the FM/I/FM junction, the spin-up process and the spin-down process are separated on the time scales. As the self-interference delay has the spin-dependent features, the variations of spin-dependent dwell-time and spin-dependent group-delay time with the structure parameters appear different features, especially, in low incident energy range. These different features show up as that the group delay times for the spin-up electrons are always longer than those for spin-down electrons when the barrier height or incident energy increase. In contrast, the dwell times for the spin-up electrons are longer (shorter) than those for spin-down electrons when the barrier heights (the incident energy) are under a certain value. When the barrier heights (the incident energy) exceed a certain value, the dwell times for the spin-up electrons turn out to be shorter (longer) than those for spin-down electrons. In addition, the group delay time and the dwell time for spin-up and down electrons also relies on the comparative direction of magnetization in two FM layers and tends to saturation with the thickness of the barrier.

  17. Perpendicular spin injection and polarization features in InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D. [Lehrstuhl fuer Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Soldat, Henning; Li, Mingyuan; Gerhardt, Nils C.; Hofmann, Martin [Lehrstuhl fuer Photonik und Terahertztechnologie, Ruhr-Universitaet Bochum (Germany); Stromberg, Frank; Warland, Anne; Wende, Heiko; Keune, Werner [Fachbereich Physik, Center for Nanointegration Duisburg-Essen, Universitaet Duisburg-Essen (Germany); Ebbing, Astrid [Lehrstuhl fuer Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Experimentalphysik IV - Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Petracic, Oleg [Experimentalphysik IV - Festkoerperphysik, Ruhr-Universitaet Bochum (Germany)

    2011-07-01

    Self assembled InAs quantum dots (QDs) are zero dimensional multilevel systems with long spin relaxation times and thus offer great potential for spin optoelectronic research and applications. Electrically injected spin polarization is efficiently transferred into circularly polarized photons if the injected spin is oriented perpendicularly to the growth plane. The optical polarization from an ensemble of QDs in a spin-LED is strongly magnetic field dependent due to the orbital character of the transitions of excited carriers. An unambiguous separation of spin injection and Zeeman shift is obtained by investigating the magnetic field dependence of the circular polarisation of the spin-LED emission. Here we present and analyze perpendicular spin injection from Fe/Tb magnetic injectors at room temperature and in remanence. Polarization features of excited transitions are discussed.

  18. Spin kinetic Monte Carlo method for nanoferromagnetism and magnetization dynamics of nanomagnets with large magnetic anisotropy

    Institute of Scientific and Technical Information of China (English)

    LIU Bang-gui; ZHANG Kai-cheng; LI Ying

    2007-01-01

    The Kinetic Monte Carlo (KMC) method based on the transition-state theory, powerful and famous for sim-ulating atomic epitaxial growth of thin films and nanostruc-tures, was used recently to simulate the nanoferromagnetism and magnetization dynamics of nanomagnets with giant mag-netic anisotropy. We present a brief introduction to the KMC method and show how to reformulate it for nanoscale spin systems. Large enough magnetic anisotropy, observed exper-imentally and shown theoretically in terms of first-principle calculation, is not only essential to stabilize spin orientation but also necessary in making the transition-state barriers dur-ing spin reversals for spin KMC simulation. We show two applications of the spin KMC method to monatomic spin chains and spin-polarized-current controlled composite nano-magnets with giant magnetic anisotropy. This spin KMC method can be applied to other anisotropic nanomagnets and composite nanomagnets as long as their magnetic anisotropy energies are large enough.

  19. Optically programmable electron spin memory using semiconductor quantum dots.

    Science.gov (United States)

    Kroutvar, Miro; Ducommun, Yann; Heiss, Dominik; Bichler, Max; Schuh, Dieter; Abstreiter, Gerhard; Finley, Jonathan J

    2004-11-04

    The spin of a single electron subject to a static magnetic field provides a natural two-level system that is suitable for use as a quantum bit, the fundamental logical unit in a quantum computer. Semiconductor quantum dots fabricated by strain driven self-assembly are particularly attractive for the realization of spin quantum bits, as they can be controllably positioned, electronically coupled and embedded into active devices. It has been predicted that the atomic-like electronic structure of such quantum dots suppresses coupling of the spin to the solid-state quantum dot environment, thus protecting the 'spin' quantum information against decoherence. Here we demonstrate a single electron spin memory device in which the electron spin can be programmed by frequency selective optical excitation. We use the device to prepare single electron spins in semiconductor quantum dots with a well defined orientation, and directly measure the intrinsic spin flip time and its dependence on magnetic field. A very long spin lifetime is obtained, with a lower limit of about 20 milliseconds at a magnetic field of 4 tesla and at 1 kelvin.

  20. Spin-controlled plasmonics via optical Rashba effect

    Energy Technology Data Exchange (ETDEWEB)

    Shitrit, Nir; Yulevich, Igor; Kleiner, Vladimir; Hasman, Erez, E-mail: mehasman@technion.ac.il [Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000 (Israel)

    2013-11-18

    Observation of the optical Rashba effect in plasmonics is reported. Polarization helicity degeneracy removal, associated with the inversion symmetry violation, is attributed to the surface symmetry design via anisotropic nanoantennas with space-variant orientations. By utilizing the Rashba-induced momentum in a nanoscale kagome metastructure, we demonstrated a spin-based surface plasmon multidirectional excitation under a normal-incidence illumination. The spin-controlled plasmonics via spinoptical metasurfaces provides a route for spin-based surface-integrated photonic nanodevices and light-matter interaction control, extending the light manipulation capabilities.

  1. Frequency selective tunable spin wave channeling in the magnonic network

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Odincov, S. A.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Stognij, A. I. [Scientific-Practical Materials Research Center, National Academy of Sciences of Belarus, 220072 Minsk (Belarus)

    2016-04-25

    Using the space-resolved Brillouin light scattering spectroscopy, we study the frequency and wavenumber selective spin-wave channeling. We demonstrate the frequency selective collimation of spin-wave in an array of magnonic waveguides, formed between the adjacent magnonic crystals on the surface of yttrium iron garnet film. We show the control over spin-wave propagation length by the orientation of an in-plane bias magnetic field. Fabricated array of magnonic crystal can be used as a magnonic platform for multidirectional frequency selective signal processing applications in magnonic networks.

  2. Pulsed EPR in the method of spin labels and probes

    Energy Technology Data Exchange (ETDEWEB)

    Dzuba, Sergei A [Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-08-31

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

  3. Pulsed EPR in the method of spin labels and probes

    Science.gov (United States)

    Dzuba, Sergei A.

    2007-08-01

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

  4. Experimental investigation of magnetic anisotropy in spin vortex discs

    Energy Technology Data Exchange (ETDEWEB)

    Garraud, N., E-mail: ngarraud@ufl.edu; Arnold, D. P. [Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-05-07

    We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.

  5. Characterization of hyperfine interaction between an NV electron spin and a first-shell 13C nuclear spin in diamond

    Science.gov (United States)

    Rao, K. Rama Koteswara; Suter, Dieter

    2016-08-01

    The nitrogen-vacancy (NV) center in diamond has attractive properties for a number of quantum technologies that rely on the spin angular momentum of the electron and the nuclei adjacent to the center. The nucleus with the strongest interaction is the 13C nuclear spin of the first shell. Using this degree of freedom effectively hinges on precise data on the hyperfine interaction between the electronic and the nuclear spin. Here, we present detailed experimental data on this interaction, together with an analysis that yields all parameters of the hyperfine tensor, as well as its orientation with respect to the atomic structure of the center.

  6. Thinking in Orienteering.

    Science.gov (United States)

    Johansen, Bjorn Tore

    1997-01-01

    A think-aloud technique, in which 20 orienteers verbalized their exact thoughts during orienteering, was used to examine the phenomenon of cognition during orienteering. Results indicate that orienteering is experienced as a task to be accomplished, a physical movement, and a dynamic process, and that thinking involves attuning perceptions to…

  7. 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...

  8. Quantum Spin Gyroscope

    Science.gov (United States)

    2015-07-15

    Progress Report (ONR Award No. N00014-14-1-0804) Quantum Spin Gyroscope August 2014-July 2015 Report Type: Annual Report Primary Contact E-mail... Quantum Spin Gyroscope Grant/Contract Number: N00014-14-1-0804 Principal Investigator Name: Paola Cappellaro Program Manager: Richard Tommy Willis...required large volumes. Our project aims at overcoming these drawbacks by developing a novel solid-state quantum spin gyro- scope associated with the

  9. 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.

  10. Spinon Fermi surface U (1 ) spin liquid in the spin-orbit-coupled triangular-lattice Mott insulator YbMgGaO4

    Science.gov (United States)

    Li, Yao-Dong; Lu, Yuan-Ming; Chen, Gang

    2017-08-01

    Motivated by the recent progress in the spin-orbit-coupled triangular lattice spin liquid candidate YbMgGaO4, we carry out a systematic projective symmetry group analysis and mean-field study of candidate U (1 ) spin-liquid ground states. Due to the spin-orbital entanglement of the Yb moments, the space-group symmetry operation transforms both the position and the orientation of the local moments, and hence it brings different features for the projective realization of the lattice symmetries from the cases with spin-only moments. Among the eight U (1 ) spin liquids that we find with the fermionic parton construction, only one spin-liquid state, which was proposed and analyzed by Yao Shen et al. [Nature (London) 540, 559 (2016), 10.1038/nature20614] and labeled as U1A00 in the present work, stands out and gives a large spinon Fermi surface and provides a consistent explanation for the spectroscopic results in YbMgGaO4. Further connection of this spinon Fermi surface U (1 ) spin liquid with YbMgGaO4 and the future directions are discussed. Finally, our results may apply to other spin-orbit-coupled triangular lattice spin-liquid candidates, and more broadly, our general approach can be well extended to spin-orbit-coupled spin-liquid candidate materials.

  11. Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

    Science.gov (United States)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2015-11-01

    Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

  12. Picosecond Spin Seebeck Effect

    Science.gov (United States)

    Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.

    2017-02-01

    We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal metal /Y3Fe5 O12 bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal metal /Y3Fe5 O12 interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of 108 A m-2 K-1 .

  13. Picosecond spin Seebeck effect

    OpenAIRE

    Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.

    2016-01-01

    We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect driven by an interfacial temperature difference between itinerant electrons and magnons. The measured time-evolution of spin accumulation induced by laser-excitation indicates transfer of angular momentum across Au/Y$_3$Fe$_5$O$_{12}$ and Cu/Y$_3$Fe$_5$O$_{12}$ interfaces on a picosecond time-scale. The product of spin-mixing conductance and interfacial spin Seebeck coefficient determined is...

  14. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

    1975-01-01

    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...

  15. Relaxation of quadrupole orientation in an optically pumped alkali vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E.; Tornos, J.

    1985-04-01

    The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.

  16. Electron spin dynamics in GaAsN and InGaAsN structures

    Energy Technology Data Exchange (ETDEWEB)

    Lagarde, D.; Lombez, L.; Marie, X.; Balocchi, A.; Amand, T. [Laboratoire de Nanophysique, Magnetisme et Optoelectronique, INSA 135 avenue de Rangueil 31077 Toulouse Cedex 4 (France); Kalevich, V.K.; Shiryaev, A.; Ivchenko, E.; Egorov, A. [A.F. Ioffe Physico-Technical Institute, 194021 St-Petersburg (Russian Federation)

    2007-01-15

    We report on optical orientation experiments in undoped GaAsN epilayers and InGaAsN quantum wells (QW), showing that a strong electron spin polarisation can persist at room temperature. We demonstrate that the spin dynamics in these dilute nitride structures is governed by a spin-dependent recombination process of free conduction electrons on deep paramagnetic centres. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Single crystal nuclear magnetic resonance in spinning powders

    Science.gov (United States)

    Pell, Andrew J.; Pintacuda, Guido; Emsley, Lyndon

    2011-10-01

    We present a method for selectively exciting nuclear magnetic resonances (NMRs) from well-defined subsets of crystallites from a powdered sample under magic angle spinning. Magic angle spinning induces a time dependence in the anisotropic interactions, which results in a time variation of the resonance frequencies which is different for different crystallite orientations. The proposed method exploits this by applying selective pulses, which we refer to as XS (for crystallite-selective) pulses, that follow the resonance frequencies of nuclear species within particular crystallites, resulting in the induced flip angle being orientation dependent. By selecting the radiofrequency field to deliver a 180 ○ pulse for the target orientation and employing a train of such pulses combined with cogwheel phase cycling, we obtain a high degree of orientational selectivity with the resulting spectrum containing only contributions from orientations close to the target. Typically, this leads to the selection of between 0.1% and 10% of the crystallites, and in extreme cases to the excitation of a single orientation resulting in single crystal spectra of spinning powders. Two formulations of this method are described and demonstrated with experimental examples on [1 - 13C]-alanine and the paramagnetic compound Sm2Sn2O7.

  18. Understanding political market orientation

    DEFF Research Database (Denmark)

    Ormrod, Robert P.; Henneberg, Stephan C.

    This article develops a conceptual framework and measurement model of political market orientation that consists of attitudinal and behavioural constructs. The article reports on perceived relationships among different behavioral aspects of political market orientation and the attitudinal influen......, a more surprising result is the inconclusive effect of a voter orientation on market-oriented behaviours. The article discusses the findings in the context of the existing literature in political marketing and commercial market orientation.......This article develops a conceptual framework and measurement model of political market orientation that consists of attitudinal and behavioural constructs. The article reports on perceived relationships among different behavioral aspects of political market orientation and the attitudinal...... influences of such behavior. The study includes structural equation modeling to investigate several propositions. While the results show that political parties need to focus on several different aspects of market-oriented behavior, especially using an internal and external orientation as cultural antecedents...

  19. Prótesis de cúpula monopolar en el tratamiento de fracturas y luxofracturas del radio. [Monopolar ­radial­ head ­arthroplasty­ in ­the ­treatment­ of ­fracture and ­fracture-dislocations ­of ­the ­radius.

    Directory of Open Access Journals (Sweden)

    Gerardo L. Gallucci

    2014-06-01

    Full Text Available Objetivo: Evaluar retrospectivamente los resultados clínicos y radiológicos de una serie consecutiva de pacientes con fracturas y luxofracturas de la cúpula radial a quienes se les realizó el reemplazo por una prótesis monopolar. Materiales­ y ­Métodos: Se incluyeron 20 pacientes. Criterios de inclusión: <18 años, con fracturas o luxofracturas de la cúpula radial, tratados con prótesis monoblock de titanio y seguimiento mínimo de un año. Quince eran mujeres, edad promedio 59 años. Siete eran fracturas aisladas y 13, luxofracturas. Se evaluaron el grado de aflojamiento protésico, la erosión capitelar, el ensanchamiento del espacio articular humeral lateral y las calcificaciones heterotópicas. El seguimiento fue de 26 meses. Resultados: La flexo-extensión fue de 139º-5º y la prono-supinación, de 79-79°. El arco total fue de 134°. Fuerza de puño: 84% del lado contralateral. El dolor según la escala analógica visual fue de 2, DASH: 11 puntos, 13 resultados excelentes y 6 buenos. Se detectó aflojamiento del implante (12 casos, aumento de la radiolucidez capitelar (4 casos y ensanchamiento del espacio ulnohumeral lateral (2 casos. Hubo 2 complicaciones: una neurodocitis cubital que debió ser operada y una extracción de implante por aflojamiento y dolor. Conclusiones: El reemplazo de la cúpula radial en lesiones no reconstruibles es una opción terapéutica viable, con buenos resultados funcionales a corto y mediano plazo. La recuperación de la estabilidad articular fue posible en todos los casos y el índice de aflojamiento protésico asintomático fue elevado.

  20. Toward Ultrafast Spin Dynamics in Low Dimensional Semiconductors

    Science.gov (United States)

    Chiu, Yi-Hsin

    neighboring Fe spins, as well as the resulting exchange-driven electron spin relaxation in GaAs. This lays the groundwork for this dissertation to explore low dimensional systems. Second, we work to facilitate optical studies of spin dynamics in one dimension (1D), which hasnt been possible in the past due to the fundamental challenge of optical polarization anisotropy. We propose a dielectric-matched membrane structure based on GaAs/AlGaAs core-shell nanowires. By simultaneous addressing the optical polarization anisotropy and various technical challenges, this study offers a promising route to optical investigations of 1D spin physics. Third, a novel 2D material, germanane (GeH), is investigated by continuous wave (cw) polarization-resolved photoluminescence (PL) spectroscopy as a first step toward future ultrafast pump-probe study. PL develops a finite degree of circular polarization under circular excitation (optical orientation) or in an applied magnetic field (Zeeman effect), indicating the presence of spin-polarized carriers. This study presents the first magneto-optical investigation in germanane.

  1. Entrepreneurial orientation, market orientation, and competitive environment

    DEFF Research Database (Denmark)

    Sørensen, Hans Eibe; Cadogan, John W.

    orientation, and competitive environment shape business performance via a three-way interaction. We test the model using primary data from the CEOs of 270 CEO of manufacturing firms, together with secondary data on these firms' profit performance. An assessment of the results indicates that customer......This study sheds light on the role that the competitive environment plays in determining how elements of market orientation and elements of entrepreneurial orientation interact to influence business success. We develop a model in which we postulate that market orientation, entrepreneurial...... orientations. Also, these moderating effects are stronger for firms operating in highly competitive environments. For the innovativeness component of entrepreneurship, however, the positive relationship between innovativeness and ROA decreases as the competitive environment becomes more hostile....

  2. Object oriented methods

    CERN Document Server

    Graham, Ian

    1994-01-01

    This book is a revision of Ian Graham's successful survey of the whole area of object technology. It covers object- oriented programming, object-oriented design, object- oriented analysis, object-oriented databases and treats several related technologies. New to this edition are more applications of object-oriented methods and more coverage of object-oriented database products available. Graham has also doubled the design and analysis material that examines over 60 different approaches - making this the most comprehensive book on the market. Also new is the foreword by Grady Booch.

  3. Nucleon Spin: Summary

    OpenAIRE

    Close, Frank

    1995-01-01

    This talk summarises the discussions during the conference on the spin structure of the nucleon held at Erice; July 1995. The summary focuses on where we have come, where we are now, and the emerging questions that direct where we go next in the quest to understand the nucleon spin.

  4. 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.

  5. Antiferromagnetic Spin Seebeck Effect

    Science.gov (United States)

    Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand

    2016-03-01

    We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2 . A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30 nm )/Pt (4 nm) grown by molecular beam epitaxy on a MgF2 (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2-80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9 T ) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.

  6. Single spin magnetic resonance

    Science.gov (United States)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  7. 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).

  8. Operator Spin Foam Models

    CERN Document Server

    Bahr, Benjamin; Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

    2010-01-01

    The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as the main tool. An equivalence relation we impose in the set of the operator spin foams allows to split the faces and the edges of the foams. The consistency with that relation requires introduction of the (familiar for the BF theory) face amplitude. The operator spin foam models are defined quite generally. Imposing a maximal symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with demanding consistency with splitting the edges, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on Spin(4) BF spin foam model is exactly the way we tend to view 4d quantum gravity, starting with the BC model and continuing with the EPRL or FK models. That makes...

  9. Antiferromagnetic spin Seebeck Effect

    OpenAIRE

    Wu, SM; W. Zhang; Kc, A; Borisov, P.; Pearson, JE; Jiang, JS; Lederman, D.; Hoffmann, A.; Bhattacharya, A

    2015-01-01

    We report on the observation of the spin Seebeck effect in antiferromagnetic MnF_{2}. A device scale on-chip heater is deposited on a bilayer of MnF_{2} (110) (30  nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF_{2} (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF_{2} through the inverse spin Hall effect. The low temperature (2-80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop t...

  10. Spin-transport-phenomena in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias Klaus

    2012-07-19

    Assuming that one could deterministically inject, transport, manipulate, store and detect spin information in solid state devices, the well-established concepts of charge-based electronics could be transferred to the spin realm. This thesis explores the injection, transport, manipulation and storage of spin information in metallic conductors, semiconductors, as well as electrical insulators. On the one hand, we explore the spin-dependent properties of semiconducting zinc oxide thin films deposited via laser-molecular beam epitaxy (laser-MBE). After demonstrating that the zinc oxide films fabricated during this thesis have excellent structural, electrical, and optical properties, we investigate the spin-related properties by optical pump/probe, electrical injection/optical detection, and all electrical spin valve-based experiments. The two key results from these experiments are: (i) Long-lived spin states with spin dephasing times of 10 ns at 10 K related to donor bound excitons can be optically addressed. (ii) The spin dephasing times relevant for electrical transport-based experiments are {<=} 2 ns at 10 K and are correlated with structural quality. On the other hand we focus on two topics of current scientific interest: the comparison of the magnetoresistance to the magnetothermopower of conducting ferromagnets, and the investigation of pure spin currents generated in ferromagnetic insulator/normal metal hybrid structures. We investigate the magnetoresistance and magnetothermopower of gallium manganese arsenide and Heusler thin films as a function of external magnetic field orientation. Using a series expansion of the resistivity and Seebeck tensors and the inherent symmetry of the sample's crystal structure, we show that a full quantitative extraction of the transport tensors from such experiments is possible. Regarding the spin currents in ferromagnetic insulator/normal metal hybrid structures we studied the spin mixing conductance in yttrium iron garnet

  11. Fractionalized spin-wave continuum in kagome spin liquids

    Science.gov (United States)

    Mei, Jia-Wei; Wen, Xiao-Gang

    Motivated by spin-wave continuum (SWC) observed in recent neutron scattering experiments in Herbertsmithite, we use Gutzwiller-projected wave functions to study dynamic spin structure factor S (q , ω) of spin liquid states on the kagome lattice. Spin-1 excited states in spin liquids are represented by Gutzwiller-projected two-spinon excited wave functions. We investigate three different spin liquid candidates, spinon Fermi-surface spin liquid (FSL), Dirac spin liquid (DSL) and random-flux spin liquid (RSL). FSL and RSL have low energy peaks in S (q , ω) at K points in the extended magnetic Brillouin zone, in contrast to experiments where low energy peaks are found at M points. There is no obviuos contradiction between DSL and neutron scattering measurements. Besides a fractionalized spin (i.e. spin-1/2), spinons in DSL carry a fractionalized crystal momentum which is potentially detectable in SWC in the neutron scattering measurements.

  12. Observation of spin diffusion in zero-field magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Suter, D.; Jarvie, T.P.; Sun, B.; Pines, A.

    1987-07-06

    We report the measurement of spin diffusion at zero field, observed by two-dimensional deuterium magnetic resonance of a polycrystalline sample. This demonstrates for the first time an appealing feature of pulsed zero-field magnetic resonance, namely the potential for structure determination in solids without the need for single crystals or oriented samples.

  13. Spin alignment of dark matter halos in filaments and walls

    NARCIS (Netherlands)

    Aragon-Calvo, Miguel A.; van de Weygaert, Rien; Jones, Bernard J. T.; van der Hulst, J. M.

    2007-01-01

    The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter halos are significantly correlated with each other and with the orientation of their host structures. The shap

  14. Spin alignment of dark matter haloes in filaments and walls

    NARCIS (Netherlands)

    Aragón-Calvo, M. A.; Weygaert, R. van de; Jones, B. J. T.; Hulst, T. van der

    2006-01-01

    Abstract: The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host structure

  15. Spin transport at interfaces with spin-orbit coupling: Formalism

    Science.gov (United States)

    Amin, V. P.; Stiles, M. D.

    2016-09-01

    We generalize magnetoelectronic circuit theory to account for spin transfer to and from the atomic lattice via interfacial spin-orbit coupling. This enables a proper treatment of spin transport at interfaces between a ferromagnet and a heavy-metal nonmagnet. This generalized approach describes spin transport in terms of drops in spin and charge accumulations across the interface (as in the standard approach), but additionally includes the responses from in-plane electric fields and offsets in spin accumulations. A key finding is that in-plane electric fields give rise to spin accumulations and spin currents that can be polarized in any direction, generalizing the Rashba-Edelstein and spin Hall effects. The spin accumulations exert torques on the magnetization at the interface when they are misaligned from the magnetization. The additional out-of-plane spin currents exert torques via the spin-transfer mechanism on the ferromagnetic layer. To account for these phenomena we also describe spin torques within the generalized circuit theory. The additional effects included in this generalized circuit theory suggest modifications in the interpretations of experiments involving spin-orbit torques, spin pumping, spin memory loss, the Rashba-Edelstein effect, and the spin Hall magnetoresistance.

  16. Spin Hall and spin Nernst effects in graphene with intrinsic and Rashba spin-orbit interactions

    Institute of Scientific and Technical Information of China (English)

    Zhu Guo-Bao

    2012-01-01

    The spin Hall and spin Nernst effects in graphene are studied based on Green's function formalism.We calculate intrinsic contributions to spin Hall and spin Nernst conductivities in the Kane-Mele model with various structures.When both intrinsic and Rashba spin-orbit interactions are present,their interplay leads to some characteristics of the dependence of spin Hall and spin Nernst conductivities on the Fermi level.When the Rashba spin-orbit interaction is smaller than intrinsic spin-orbit coupling,a weak kink in the conductance appears.The kink disappears and a divergence appears when the Rashba spin-orbit interaction enhances.When the Rashba spin-orbit interaction approaches and is stronger than intrinsic spin-orbit coupling,the divergence becomes more obvious.

  17. Half-metallic superconducting triplet spin valve

    Science.gov (United States)

    Halterman, Klaus; Alidoust, Mohammad

    2016-08-01

    We theoretically study a finite-size S F1N F2 spin valve, where a normal metal (N ) insert separates a thin standard ferromagnet (F1) and a thick half-metallic ferromagnet (F2). For sufficiently thin superconductor (S ) widths close to the coherence length ξ0, we find that changes to the relative magnetization orientations in the ferromagnets can result in substantial variations in the transition temperature Tc, consistent with experimental results [Singh et al., Phys. Rev. X 5, 021019 (2015), 10.1103/PhysRevX.5.021019]. Our results demonstrate that, in good agreement with the experiment, the variations are largest in the case where F2 is in a half-metallic phase and thus supports only one spin direction. To pinpoint the origins of this strong spin-valve effect, both the equal-spin f1 and opposite-spin f0 triplet correlations are calculated using a self-consistent microscopic technique. We find that when the magnetization in F1 is tilted slightly out of plane, the f1 component can be the dominant triplet component in the superconductor. The coupling between the two ferromagnets is discussed in terms of the underlying spin currents present in the system. We go further and show that the zero-energy peaks of the local density of states probed on the S side of the valve can be another signature of the presence of superconducting triplet correlations. Our findings reveal that for sufficiently thin S layers, the zero-energy peak at the S side can be larger than its counterpart in the F2 side.

  18. Out-of-plane spin polarization of edge currents in Chern insulator with Rashba spin-orbit interaction

    Science.gov (United States)

    Chen, Tsung-Wei; Hsiao, Chin-Lun; Hu, Chong-Der

    2016-07-01

    We investigate the change in the non-zero Chern number and out-of-plane spin polarization of the edge currents in a honeycomb lattice with the Haldane-Rashba interaction. This interaction breaks the time-reversal symmetry due to the Haldane phase caused by a current loop at the site-I and site-II atoms, and also accounts for the Rashba-type spin-orbit interaction. The Rashba spin-orbit interaction increases the number of Dirac points and the band-touching phenomenon can be generated by tuning the on-site potential in the non-zero Haldane phase. By using the Pontryagin winding number and numerical Berry curvature methods, we find that the Chern number pattern is {+2, -1, 0} and {-2, +1, 0} for the positive and negative Haldane phase, respectively. A non-zero Chern number is called a Chern-insulating phase. We discovered that changes in both the Haldane phase and on-site potential leads to a change in the orientation of the bulk spin polarization of site-I and site-II atoms. Interestingly, in a ribbon with a zigzag edge, which naturally has site-I atoms at one outer edge and site-II atoms at the opposite outer edge, the spin polarization of the edge states approximately obeys the properties of bulk spin polarization regardless of the change in the Chern number. In addition, even when the Chern number changes from  +2 to  -1 (or  -2 to  +1), by tuning the strength of the on-site potential, the sign of the spin polarization of the edge states persists. This approximate bulk-edge correspondence of the spin polarization in the Haldane-Rashba system would play an important role in spintronics, because it enables us to control the orientation of the spin polarization in a single Chern-insulating phase.

  19. Spin from defects in two-dimensional quantum field theory

    CERN Document Server

    Novak, Sebastian

    2015-01-01

    We build two-dimensional quantum field theories on spin surfaces starting from theories on oriented surfaces with networks of topological defect lines and junctions. The construction uses a combinatorial description of the spin structure in terms of a triangulation equipped with extra data. The amplitude for the spin surfaces is defined to be the amplitude for the underlying oriented surface together with a defect network dual to the triangulation. Independence of the triangulation and of the other choices follows if the line defect and junctions are obtained from a Delta-separable Frobenius algebra with involutive Nakayama automorphism in the monoidal category of topological defects. For rational conformal field theory we can give a more explicit description of the defect category, and we work out two examples related to free fermions in detail: the Ising model and the so(n) WZW model at level 1.

  20. They Call it Orienteering

    Science.gov (United States)

    Wexler, Mark

    1977-01-01

    Through the use of personal anecdotes, the author details his initial experience with orienteering, a sport rapidly increasing in popularity that teaches people not to get lost in the woods. Sources of information about orienteering are provided. (BT)

  1. Theories of Sexual Orientation.

    Science.gov (United States)

    Storms, Michael D.

    1980-01-01

    Results indicated homosexuals, heterosexuals, and bisexuals did not differ within each sex on measures of masculinity and femininity. Strong support was obtained for the hypothesis that sexual orientation relates primarily to erotic fantasy orientation. (Author/DB)

  2. To Spin or Not to Spin?

    Institute of Scientific and Technical Information of China (English)

    Tina Boikos

    2008-01-01

    @@ The alarm has just gone off. Do I really have to get up? I wonder. Originally, signing up for an early-morning spinning class seemed like a good idea; it jump-starts the day with some well-needed exercise.

  3. The role of the fast motion of the spin label in the interpretation of EPR spectra for spin-labeled macromolecules.

    Science.gov (United States)

    Timofeev, Vladimir P; Nikolsky, Dmitriy O

    2003-12-01

    The spin label method was used to observe the nature of the fast motions of side chains in protein monocrystals. The EPR spectra of spin-labeled lysozyme monocrystals (with different orientations of the tetragonal protein crystal in relation to the direction of the magnetic field) were interpreted using the method of molecular dynamics (MD). Within the proposed simple model, MD calculations of the spin label motion trajectories are performed in a reasonable real time. The model regards the protein molecule as frozen as a whole and the spin-labeled amino acid residue as unfrozen. To calculate the trajectories in vacuum, a model of spin-labeled lysozyme was assembled, and the parameters of the force fields were specified for atoms of the protein molecule, including the spin label. The calculations show that the protein environment sterically limits the area of the possible angular reorientations for the NO reporter group of the nitroxide (within the spin label), and this, in turn, affects the shape of the EPR spectrum. However, it turned out that the spread in the positions of the reporter group in the angle space strictly adheres to the Gaussian distribution. Using the coordinates of the spin label atoms obtained by the MD method within a selected time range and considering the distribution of the spin label states over the ensemble of spin-labeled macromolecules in a crystal, the EPR spectra of spin-labeled lysozyme monocrystals were simulated. The resultant theoretical EPR spectra appeared to be similar to experimental ones.

  4. Most spin-1/2 transition-metal ions do have single ion anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jia; Whangbo, Myung-Hwan, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 (United States); Koo, Hyun-Joo [Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Xiang, Hongjun, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433 (China); Kremer, Reinhard K. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2014-09-28

    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  5. Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

    Science.gov (United States)

    Farr, Will M; Stevenson, Simon; Miller, M Coleman; Mandel, Ilya; Farr, Ben; Vecchio, Alberto

    2017-08-23

    The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10(-7) against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

  6. Distinguishing spin-aligned and isotropic black hole populations with gravitational waves

    Science.gov (United States)

    Farr, Will M.; Stevenson, Simon; Miller, M. Coleman; Mandel, Ilya; Farr, Ben; Vecchio, Alberto

    2017-08-01

    The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the ‘effective’ spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10‑7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

  7. Entrepreneurial orientation, market orientation, and competitive environment

    DEFF Research Database (Denmark)

    Sørensen, Hans Eibe; Cadogan, John W.

    orientation, and competitive environment shape business performance via a three-way interaction. We test the model using primary data from the CEOs of 270 CEO of manufacturing firms, together with secondary data on these firms' profit performance. An assessment of the results indicates that customer...... orientation moderates the positive relationships between the competitiveness element of entrepreneurial orientation and market share and return on assets (ROA): the positive relationships between competitiveness and market share and competitiveness and ROA become stronger the greater the firms' customer...

  8. Tensorial Orientation Scores

    NARCIS (Netherlands)

    van de Gronde, Jasper J.; Azzopardi, George; Petkov, Nicolai

    2015-01-01

    Orientation scores are representations of images built using filters that only select on orientation (and not on the magnitude of the frequency). Importantly, they allow (easy) reconstruction, making them ideal for use in a filtering pipeline. Traditionally a specific set of orientations has to be c

  9. Dual-frequency ferromagnetic resonance to measure spin current coupling in multilayers

    Science.gov (United States)

    Adur, Rohan; Du, Chunhui; Wang, Hailong; Manuilov, Sergei A.; Yang, Fengyuan; Hammel, P. Chris

    2014-08-01

    Spin pumping is a method for injecting a pure spin current into a non-magnetic metal (NM) by inducing precession of a neighboring ferromagnet (FM) at its ferromagnetic resonance frequency. A popular method to detect spin current uses the Inverse Spin Hall Effect (ISHE) to convert the spin current to a detectable charge current and hence a voltage. In order to better understand the role of time independent and high frequency contributions to spin pumping, we sought to detect we attempt to detect spin currents by using a second microwave frequency to detect changes in linewidth of a second ferromagnet due to the spin-torque induced by the spin current from the first ferromagnet. This dual resonance is achieved by pairing a custom broadband coplanar transmission line with the high-Q resonant cavity of a commercial electron paramagnetic resonance spectrometer. This technique is general enough that it should enable the investigation of spin currents in any FM-NM-FM system, for any orientation of external field, and is not sensitive to voltage artifacts often found in ISHE measurements. We find that the condition for simultaneous resonance generates a dc spin current that is too small to produce a measurable change in linewidth of the second ferromagnet, confirming the dominance of ac spin currents in linewidth enhancement measurements.

  10. Spin forming development

    Science.gov (United States)

    Gates, W. G.

    1982-05-01

    Bendix product applications require the capability of fabricating heavy gage, high strength materials. Five commercial sources have been identified that have the capability of spin forming metal thicknesses greater than 9.5 mm and four equipment manufacturers produce machines with this capability. Twelve assemblies selected as candidates for spin forming applications require spin forming of titanium, 250 maraging steel, 17-4 pH stainless steel, Nitronic 40 steel, 304 L stainless steel, and 6061 aluminum. Twelve parts have been cold spin formed from a 250 maraging steel 8.1 mm wall thickness machine preform, and six have been hot spin formed directly from 31.8-mm-thick flat plate. Thirty-three Ti-6Al-4V titanium alloy parts and 26 17-4 pH stainless steel parts have been hot spin formed directly from 31.8-mm-thick plate. Hot spin forming directly from plate has demonstrated the feasibility and favorable economics of this fabrication technique for Bendix applications.

  11. Representation of Spin Group Spin(p, q)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The representation (&)(p, q) of spin group Spin(p, q) in any dimensional space is given by induction, and the relation between two representations, which are obtained in two kinds of inductions from Spin(p, q) to Spin(p + 1, q + 1)are studied.

  12. SPIN Tutorial: How to Become a SPIN Doctor

    NARCIS (Netherlands)

    Ruys, T.C.; Bosnacki, D.; Leue, S.

    2002-01-01

    SPIN is a model checker for the verification of software systems. SPIN uses a high level language called PROMELA to specify systems descriptions. The goal of this tutorial is to introduce novice users to both PROMELA and SPIN. The tutorial itself is divided into two parts. The BASIC SPIN part is tar

  13. 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.

  14. 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.

  15. Stretchable Persistent Spin Helices in GaAs Quantum Wells

    Science.gov (United States)

    Dettwiler, Florian; Fu, Jiyong; Mack, Shawn; Weigele, Pirmin J.; Egues, J. Carlos; Awschalom, David D.; Zumbühl, Dominik M.

    2017-07-01

    The Rashba and Dresselhaus spin-orbit (SO) interactions in 2D electron gases act as effective magnetic fields with momentum-dependent directions, which cause spin decay as the spins undergo arbitrary precessions about these randomly oriented SO fields due to momentum scattering. Theoretically and experimentally, it has been established that by fine-tuning the Rashba α and renormalized Dresselhaus β couplings to equal fixed strengths α =β , the total SO field becomes unidirectional, thus rendering the electron spins immune to decay due to momentum scattering. A robust persistent spin helix (PSH), i.e., a helical spin-density wave excitation with constant pitch P =2 π /Q , Q =4 m α /ℏ2, has already been experimentally realized at this singular point α =β , enhancing the spin lifetime by up to 2 orders of magnitude. Here, we employ the suppression of weak antilocalization as a sensitive detector for matched SO fields together with independent electrical control over the SO couplings via top gate voltage VT and back gate voltage VB to extract all SO couplings when combined with detailed numerical simulations. We demonstrate for the first time the gate control of the renormalized β and the continuous locking of the SO fields at α =β ; i.e., we are able to vary both α and β controllably and continuously with VT and VB, while keeping them locked at equal strengths. This makes possible a new concept: "stretchable PSHs," i.e., helical spin patterns with continuously variable pitches P over a wide parameter range. Stretching the PSH, i.e., gate controlling P while staying locked in the PSH regime, provides protection from spin decay at the symmetry point α =β , thus offering an important advantage over other methods. This protection is limited mainly by the cubic Dresselhaus term, which breaks the unidirectionality of the total SO field and causes spin decay at higher electron densities. We quantify the cubic term, and find it to be sufficiently weak so that

  16. Stretchable Persistent Spin Helices in GaAs Quantum Wells

    Directory of Open Access Journals (Sweden)

    Florian Dettwiler

    2017-07-01

    Full Text Available The Rashba and Dresselhaus spin-orbit (SO interactions in 2D electron gases act as effective magnetic fields with momentum-dependent directions, which cause spin decay as the spins undergo arbitrary precessions about these randomly oriented SO fields due to momentum scattering. Theoretically and experimentally, it has been established that by fine-tuning the Rashba α and renormalized Dresselhaus β couplings to equal fixed strengths α=β, the total SO field becomes unidirectional, thus rendering the electron spins immune to decay due to momentum scattering. A robust persistent spin helix (PSH, i.e., a helical spin-density wave excitation with constant pitch P=2π/Q, Q=4mα/ℏ^{2}, has already been experimentally realized at this singular point α=β, enhancing the spin lifetime by up to 2 orders of magnitude. Here, we employ the suppression of weak antilocalization as a sensitive detector for matched SO fields together with independent electrical control over the SO couplings via top gate voltage V_{T} and back gate voltage V_{B} to extract all SO couplings when combined with detailed numerical simulations. We demonstrate for the first time the gate control of the renormalized β and the continuous locking of the SO fields at α=β; i.e., we are able to vary both α and β controllably and continuously with V_{T} and V_{B}, while keeping them locked at equal strengths. This makes possible a new concept: “stretchable PSHs,” i.e., helical spin patterns with continuously variable pitches P over a wide parameter range. Stretching the PSH, i.e., gate controlling P while staying locked in the PSH regime, provides protection from spin decay at the symmetry point α=β, thus offering an important advantage over other methods. This protection is limited mainly by the cubic Dresselhaus term, which breaks the unidirectionality of the total SO field and causes spin decay at higher electron densities. We quantify the cubic term, and find it to be

  17. Quantum Spin Hall Effect

    Energy Technology Data Exchange (ETDEWEB)

    Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-01-15

    The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.

  18. 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

  19. 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

  20. SPINning parallel systems software.

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-03-15

    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.

  1. Correlation Functions and Spin

    CERN Document Server

    Tyc, T

    2000-01-01

    The k-electron correlation function of a free chaotic electron beam is derived with the spin degree of freedom taken into account. It is shown that it can be expressed with the help of correlation functions for a polarized electron beam of all orders up to k and the degree of spin polarization. The form of the correlation function suggests that if the electron beam is not highly polarized, observing multi-particle correlations should be difficult. The result can be applied also to chaotic photon beams, the degree of spin polarization being replaced by the degree of polarization.

  2. Spin transition in [Fe

    Science.gov (United States)

    Garcia, Y.; Ksenofontov, V.; Campbell, S. J.; Lord, J. S.; Boland, Y.; Gütlich, P.

    2004-12-01

    The reversible thermal spin transition which occurs in [Fe(phen)2(NCS)2] around T1/2 177 K has been investigated by muon spin relaxation (μSR) (10-280 K). The depolarisation curves are well described by two Lorentzian lines represent fast and slow components in the decay curves, with the initial asymmetry parameter of the fast component found to track the spin transition in [Fe(phen)2(NCS)2]. Comparison of zero-field and transverse field (20 Oe) μSR measurements shows that diamagnetic muonic species occur over the entire temperature range.

  3. Method for estimating spin-spin interactions from magnetization curves

    Science.gov (United States)

    Tamura, Ryo; Hukushima, Koji

    2017-02-01

    We develop a method to estimate the spin-spin interactions in the Hamiltonian from the observed magnetization curve by machine learning based on Bayesian inference. In our method, plausible spin-spin interactions are determined by maximizing the posterior distribution, which is the conditional probability of the spin-spin interactions in the Hamiltonian for a given magnetization curve with observation noise. The conditional probability is obtained with the Markov chain Monte Carlo simulations combined with an exchange Monte Carlo method. The efficiency of our method is tested using synthetic magnetization curve data, and the results show that spin-spin interactions are estimated with a high accuracy. In particular, the relevant terms of the spin-spin interactions are successfully selected from the redundant interaction candidates by the l1 regularization in the prior distribution.

  4. Spin and wavelength multiplexed nonlinear metasurface holography

    Science.gov (United States)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  5. Investigation of spin torque driven magnetization reversal in elliptical elements

    Science.gov (United States)

    Montgomery, Angelique; Mewes, Claudia K. A.; Mewes, Tim

    2011-03-01

    Spin transfer torque [1, 2] can be utilized to switch the magnetization in small ferromagnetic elements, which can be used to implement a magnetic random access memory. One crucial parameter for spin torque switching is the critical current required to achieve switching. To investigate spin transfer torque we simulate the magnetization dynamics using our Matlab based micromagnetic code (M3) , which uses a fast Fourier transform method to evaluate the longrange magnetostatic field, exchange interaction is implemented using 6, 12 or 26 neighbor methods and also includes adiabatic and non-adiabatic spin torque terms. We have performed simulations using different mesh sizes to examine the influence of the cell size on the micromagnetic results. We have investigated the influence of the current density and pinned layer orientation on the magnetization dynamics and in particular on the switching time. This work was supported by REU supplement #1023069 for NSF DMR #0804243.

  6. Feedback-cooling of an atomic spin ensemble

    CERN Document Server

    Behbood, N; Colangelo, G; Ciurana, F Martin; Sewell, R J; 1,; Mitchell, M W

    2013-01-01

    We describe a measurement-and-feedback technique to deterministically prepare low-entropy states of atomic spin ensembles. Using quantum non-demolition measurement and incoherent optical feedback, we drive arbitrary states in the spin-orientation space toward the origin of the spin space. We observe 12 dB of spin noise reduction, or a factor of 63 reduction in phase-space volume. We find optimal feedback conditions and show that multi-stage feedback is advantageous. An input-output calculation of quantum noise incorporating realistic quantum noise sources and experimental limitations agrees well with the observations. The method may have application to generation of exotic phases of ultracold gases, for example macroscopic singlet states and valence-bond solids.

  7. Electrical detection of spin hyperpolarization in InP

    Science.gov (United States)

    Caspers, Christian; Ansermet, Jean-Philippe

    2014-09-01

    The electrical detection of surface spin polarization in Indium Phosphide (InP) is demonstrated. Using a planar four-terminal architecture on top of semi-insulating Fe:InP (001) wafers, optical orientation is separated from electrical detection. Spin filter tunnel contacts consisting of InP/oxide/Co reveal significant asymmetries in the differential resistance upon helicity change of the optical pumping. The iron-rich tunnel oxide provides the main spin selection mechanism. A reproducible helicity-dependent asymmetry as high as 18% could be observed at T = 55 K and an external induction field μ0H = 1 T. At room temperature and zero external field, a helicity-dependent asymmetry of 6% suggests the stand-alone applicability of the device either as an electronic spin sensor or as an optical helicity sensor.

  8. Electrical detection of spin hyperpolarization in InP

    Energy Technology Data Exchange (ETDEWEB)

    Caspers, Christian; Ansermet, Jean-Philippe [Laboratoire de Physique des Matériaux Nanostructurés, École Polytechnique Fédérale de Lausanne EPFL, 1015 Lausanne (Switzerland)

    2014-09-29

    The electrical detection of surface spin polarization in Indium Phosphide (InP) is demonstrated. Using a planar four-terminal architecture on top of semi-insulating Fe:InP (001) wafers, optical orientation is separated from electrical detection. Spin filter tunnel contacts consisting of InP/oxide/Co reveal significant asymmetries in the differential resistance upon helicity change of the optical pumping. The iron-rich tunnel oxide provides the main spin selection mechanism. A reproducible helicity-dependent asymmetry as high as 18% could be observed at T = 55 K and an external induction field μ{sub 0}H = 1 T. At room temperature and zero external field, a helicity-dependent asymmetry of 6% suggests the stand-alone applicability of the device either as an electronic spin sensor or as an optical helicity sensor.

  9. Coupling of Photonic and Electronic Spin Catalyzed by Diatomic Molecules

    Science.gov (United States)

    Gay, Timothy

    2011-05-01

    Recent experiments involving the collisions of polarized photons or polarized electrons with simple diatomic molecules have shown novel ways in which the net spin of electrons can be converted into the net spin of photons following the collisions, or vice versa. I will discuss three recent experiments that illustrate such transformations: the production of nuclear rotational spin in nitrogen molecules excited by polarized electrons with the subsequent emission of polarized photons, the excitation by polarized electrons of rotational eigenstates of hydrogen molecules and the subsequent emission of circularly-polarized light, and the photolysis of hydrogen molecules by circularly-polarized light yielding photofragments that ``spin the wrong way.'' To our knowledge, these latter measurements represent the first observation of photofragment orientation by direct observation of the polarization of the photofragment fluoresence. Work supported by the NSF through grant PHY-0821385, the DOE through the use of the ALS at LBL, and ANSTO (Access to Major Research Facilities Programme).

  10. Spin noise explores local magnetic fields in a semiconductor

    Science.gov (United States)

    Ryzhov, Ivan I.; Kozlov, Gleb G.; Smirnov, Dmitrii S.; Glazov, Mikhail M.; Efimov, Yurii P.; Eliseev, Sergei A.; Lovtcius, Viacheslav A.; Petrov, Vladimir V.; Kavokin, Kirill V.; Kavokin, Alexey V.; Zapasskii, Valerii S.

    2016-01-01

    Rapid development of spin noise spectroscopy of the last decade has led to a number of remarkable achievements in the fields of both magnetic resonance and optical spectroscopy. In this report, we demonstrate a new – magnetometric – potential of the spin noise spectroscopy and use it to study magnetic fields acting upon electron spin-system of an n-GaAs layer in a high-Q microcavity probed by elliptically polarized light. Along with the external magnetic field, applied to the sample, the spin noise spectrum revealed the Overhauser field created by optically oriented nuclei and an additional, previously unobserved, field arising in the presence of circularly polarized light. This “optical field” is directed along the light propagation axis, with its sign determined by sign of the light helicity. We show that this field results from the optical Stark effect in the field of the elliptically polarized light. This conclusion is supported by theoretical estimates. PMID:26882994

  11. Proper orientation of cacti

    OpenAIRE

    Araujo, Julio; Havet, Frédéric; Linhares Sales, Claudia; Silva, Ana

    2016-01-01

    International audience; An orientation of a graph G is proper if two adjacent vertices have different in-degrees. The proper-orientation number − → χ (G) of a graph G is the minimum maximum in-degree of a proper orientation of G. In [1], the authors ask whether the proper orientation number of a planar graph is bounded. We prove that every cactus admits a proper orientation with maximum in-degree at most 7. We also prove that the bound 7 is tight by showing a cactus having no proper orientati...

  12. Spin pumping and inverse spin Hall effects—Insights for future spin-orbitronics (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: zwei@anl.gov; Jungfleisch, Matthias B.; Jiang, Wanjun; Fradin, Frank Y.; Pearson, John E.; Hoffmann, Axel, E-mail: hoffmann@anl.gov [Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States); Sklenar, Joseph; Ketterson, John B. [Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-05-07

    Quantification of spin-charge interconversion has become increasingly important in the fast-developing field of spin-orbitronics. Pure spin current generated by spin pumping acts as a sensitive probe for many bulk and interface spin-orbit effects, which has been indispensable for the discovery of many promising new spin-orbit materials. We apply spin pumping and inverse spin Hall effect experiments, as a useful metrology, and study spin-orbit effects in a variety of metals and metal interfaces. We quantify the spin Hall effects in Ir and W using the conventional bilayer structures and discuss the self-induced voltage in a single layer of ferromagnetic permalloy. Finally, we extend our discussions to multilayer structures and quantitatively reveal the spin current flow in two consecutive normal metal layers.

  13. When measured spin polarization is not spin polarization

    Science.gov (United States)

    Dowben, P. A.; Wu, Ning; Binek, Christian

    2011-05-01

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO2 and Cr2O3 illustrate some of the complications which hinders comparisons of spin polarization values.

  14. ANALYSIS ON THE SPINNING FORCES IN FLEXIBLE SPINNING OF CONES

    Institute of Scientific and Technical Information of China (English)

    Xia Qinxiang; Susumu Shima

    2003-01-01

    Flexible spinning is a new type of spinning process where spin-forming is performed without using a mandrel. Combining shearing and rolling processes, the calculation formulas of thespinning forces in flexible spinning of cones is presented. The effects of the main processing parameters, such as gripping force G applied to the blank by the inner roller, the feed rate of rollersfand the roundness radius of outer roller ro, on the spinning forces are analyzed experimentally and theoretically.

  15. Orientalism and India

    Directory of Open Access Journals (Sweden)

    Jukka Jouhki

    2006-01-01

    Full Text Available In this article Orientalism, a special hegemonic discourse about "the Orient" by Europeans is discussed by focusing on how it is manifested in a "Western" view of India. Orientalism as a discourse about the Orient is a concept first coined by Edward Said in his book Orientalism (1978 and contains a long history of European way of relating to the Orient as a counterpart of European/Western culture. In this article Orientalist discourses about India by hegemonically Western (and particularly Anglo-Saxon sources are portrayed and the so-called Indo-Orientalist essentialism defining Indianness from the outside analyzed. Moreover, a Indo-Orientalism as an imported ideology to be used in Indian nationalist discourses to emphasize a dichotomy between India and "the West" is discussed.

  16. On Nonlinear Higher Spin Curvature

    OpenAIRE

    Manvelyan, Ruben(Yerevan Physics Institute, Alikhanian Br. St. 2, Yerevan, 0036, Armenia); Mkrtchyan, Karapet; Rühl, Werner; Tovmasyan, Murad

    2011-01-01

    We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider in detail the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the deWit-Freedman curvature.

  17. On nonlinear higher spin curvature

    Energy Technology Data Exchange (ETDEWEB)

    Manvelyan, Ruben, E-mail: manvel@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Mkrtchyan, Karapet, E-mail: karapet@yerphi.a [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Ruehl, Werner, E-mail: ruehl@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Tovmasyan, Murad, E-mail: mtovmasyan@ysu.a [Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia)

    2011-05-09

    We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the de Wit-Freedman curvature.

  18. International Spin Physics 2014 Summary

    CERN Document Server

    Milner, Richard G

    2015-01-01

    The Stern-Gerlach experiment and the origin of electron spin are described in historical context. SPIN 2014 occurs on the fortieth anniversary of the first International High Energy Spin Physics Symposium at Argonne in 1974. A brief history of the international spin conference series is presented.

  19. Spin-Selective Electron Quantum Transport in Nonmagnetic MgZnO/ZnO Heterostructures.

    Science.gov (United States)

    Maryenko, D; Falson, J; Bahramy, M S; Dmitriev, I A; Kozuka, Y; Tsukazaki, A; Kawasaki, M

    2015-11-06

    We report magnetotransport measurements on a high-mobility two-dimensional electron system at the nonmagnetic MgZnO/ZnO heterointerface showing distinct behavior for electrons with spin-up and spin-down orientations. The low-field Shubnikov-de Haas oscillations manifest alternating resistance peak heights which can be attributed to distinct scattering rates for different spin orientations. The tilt-field measurements at a half-integer filling factor reveal that the majority spins show usual diffusive behavior, i.e., peaks with the magnitude proportional to the index of the Landau level at the Fermi energy. By contrast, the minority spins develop "plateaus" with the magnitude of dissipative resistivity that is fairly independent of the Landau level index and is of the order of the zero-field resistivity.

  20. Conceptual model innovation management: market orientation

    Directory of Open Access Journals (Sweden)

    L.Ya. Maljuta

    2015-06-01

    Full Text Available The article highlights issues that determine the beginning of the innovation process. Determined that until recently in Ukraine at all levels of innovation management (regional, sectoral, institutional dominated grocery orientation innovation that focus on production innovation and found that the transition to a market economy, the restructuring of production and complexity of social needs led to the strengthening of the consumer. It is proved that innovation itself – not the ultimate goal, but only a means of satisfying consumer needs. It proved that changing production conditions, complications of social needs and the need to improve the competitiveness of innovations require finding new forms of innovation. In this regard, proposed to allocate such basic scheme (model of innovation in small businesses, individual entrepreneurs, venture capital firms, eksplerents, patients, violents and commutants, spin-offs and spin-out company, network (or shell company and a network of small businesses.

  1. Coherent spin manipulation in molecular semiconductors: getting a handle on organic spintronics.

    Science.gov (United States)

    Lupton, John M; McCamey, Dane R; Boehme, Christoph

    2010-10-04

    Organic semiconductors offer expansive grounds to explore fundamental questions of spin physics in condensed matter systems. With the emergence of organic spintronics and renewed interest in magnetoresistive effects, which exploit the electron spin degree of freedom to encode and transmit information, there is much need to illuminate the underlying properties of spins in molecular electronic materials. For example, one may wish to identify over what length of time a spin maintains its orientation with respect to an external reference field. In addition, it is crucial to understand how adjacent spins arising, for example, in electrostatically coupled charge-carrier pairs, interact with each other. A periodic perturbation of the field may cause the spins to precess or oscillate, akin to a spinning top experiencing a torque. The quantum mechanical characteristic of the spin is then defined as the coherence time, the time over which an oscillating spin, or spin pair, maintains a fixed phase with respect to the driving field. Electron spins in organic semiconductors provide a remarkable route to performing "hands-on" quantum mechanics since permutation symmetries are controlled directly. Herein, we review some of the recent advances in organic spintronics and organic magnetoresistance, and offer an introductory description of the concept of pulsed, electrically detected magnetic resonance as a technique to manipulate and thus characterize the fundamental properties of electron spins. Spin-dependent dissociation and recombination allow the observation of coherent spin motion in a working device, such as an organic light-emitting diode. Remarkably, it is possible to distinguish between electron and hole spin resonances. The ubiquitous presence of hydrogen nuclei gives rise to strong hyperfine interactions, which appear to provide the basis for many of the magnetoresistive effects observed in these materials. Since hyperfine coupling causes quantum spin beating in electron

  2. Neutron resonance spin echo with longitudinal DC fields

    Science.gov (United States)

    Krautloher, Maximilian; Kindervater, Jonas; Keller, Thomas; Häußler, Wolfgang

    2016-12-01

    We report on the design, construction, and performance of a neutron resonance spin echo (NRSE) instrument employing radio frequency (RF) spin flippers combining RF fields with DC fields, the latter oriented parallel (longitudinal) to the neutron propagation direction (longitudinal NRSE (LNRSE)). The advantage of the longitudinal configuration is the inherent homogeneity of the effective magnetic path integrals. In the center of the RF coils, the sign of the spin precession phase is inverted by a π flip of the neutron spins, such that non-uniform spin precession at the boundaries of the RF flippers is canceled. The residual inhomogeneity can be reduced by Fresnel- or Pythagoras-coils as in the case of conventional spin echo instruments (neutron spin echo (NSE)). Due to the good intrinsic homogeneity of the B0 coils, the current densities required for the correction coils are at least a factor of three less than in conventional NSE. As the precision and the current density of the correction coils are the limiting factors for the resolution of both NSE and LNRSE, the latter has the intrinsic potential to surpass the energy resolution of present NSE instruments. Our prototype LNRSE spectrometer described here was implemented at the resonance spin echo for diverse applications (RESEDA) beamline at the MLZ in Garching, Germany. The DC fields are generated by B0 coils, based on resistive split-pair solenoids with an active shielding for low stray fields along the beam path. One pair of RF flippers at a distance of 2 m generates a field integral of ˜0.5 Tm. The LNRSE technique is a future alternative for high-resolution spectroscopy of quasi-elastic excitations. In addition, it also incorporates the MIEZE technique, which allows to achieve spin echo resolution for spin depolarizing samples and sample environments. Here we present the results of numerical optimization of the coil geometry and first data from the prototype instrument.

  3. Computing precession and spin-curvature coupling for small bodies orbiting Kerr black holes

    Science.gov (United States)

    Hughes, Scott; Ruangsri, Uchupol; Vigeland, Sarah

    2016-03-01

    A non-spinning small body that orbits a Kerr black hole follows a trajectory that looks like a geodesic corrected by ``self force'' effects that drive inspiral and shift the small body's orbital frequencies. If the small body is spinning, then additional forces arise from the coupling of its spin to the curvature of the larger black hole. In this talk, I will describe recent work to compute the precession of this small body in the frequency domain for generic orbit geometries and generic small body orientations, and show how this result can be used to compute the spin-curvature force in a computationally effective way.

  4. 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.

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

    Science.gov (United States)

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

    2015-05-01

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

  6. Spin- and angle-resolved photoemission spectroscopy study of the Au(1 1 1) Shockley surface state

    Energy Technology Data Exchange (ETDEWEB)

    Muntwiler, Matthias E-mail: m.muntwiler@physik.unizh.ch; Hoesch, Moritz; Petrov, Vladimir N.; Hengsberger, Matthias; Patthey, Luc; Shi Ming; Falub, Mihaela; Greber, Thomas; Osterwalder, Juerg

    2004-07-01

    The spin character of the splitting of the Shockley surface state on Au(111) is directly verified by measurements of the in-plane and out-of-plane spin polarizations in angle-resolved photoemission spectra. The two parabolic sub-bands that are momentum-shifted with respect to each other, reveal a distinct, opposite spin polarization that within the errors lies in the surface plane. The measured in-plane orientation of the spin vectors is consistent with the simple spin structure expected from a nearly-free-electron model, where the polarization axis is tangential to the Fermi surface of the surface state.

  7. 超声刀结合单极电凝应用于腹腔镜胃癌根治术的评价%Ultrasonic Scalpel and Monopolar Electrocoagulation in Laparoscopic-assisted Radical Gastrectomy for Gastric Carcinoma

    Institute of Scientific and Technical Information of China (English)

    鱼国盛; 汤黎明; 钱峻; 朱杰

    2011-01-01

    Objective To evaluate the outcome of ultrasonic scalpel combined with monopolar electrocoagulation in laparoscopic-assisted radical gastrectomy for gastric carcinoma. Methods From January 2010 to March 2011, 75 patients with curable gastric carcinoma underwent laparoscopic-assisted radical gastrectomy, of which 39 patients were treated solely by ultrasonic scalpel, the other 36 patients underwent ultrasonic scalpel combined with monopolar electrocoagulation. The operation time, intraoperative blood loss, number of resected lymph nodes, and postoperative drainage volume and complications were analyzed retrospectively and compared between the two groups. Results The mean operation time and blood loss of ultrasonic scalpel group were significantly more than that in the study group [ (347 ±38) min vs. (310 ±23) min, t =5. 049, P = 0. 000, and (274 ± 122) ml vs. (186 ± 90) ml, t = 3. 530, P = 0. 000]. The number of harvested lymph nodes, postoperative drainage volume and the incidence rate of complications were comparable between the two groups ( P > 0.05). Conclusion By combining ultrasonic scalpel with monopolar electrocoagulation in laparoscopic-assisted radical gastrectomy for gastric carcinoma, the advantages of the both methods can be utilized so that to reduce operation time and blood loss,and make lymph nodes resection easier.%目的 评价腹腔镜胃癌根治术中联合应用超声刀及单极电凝的效果.方法 回顾分析2010年1月~2011年3月75例腹腔镜胃癌D2根治术的临床资料,前39例单纯使用超声刀(超声刀组),后36例联合应用超声刀与单极电凝(联合组).比较2组手术时间、术中出血量、平均清扫淋巴结个数、术后引流量及术后并发症方面的差异.结果 与超声刀组相比,联合组术中出血少[(274±122)ml vs.(186±90) ml,t=3.530,P=0.000],手术时间短[(347±38)min vs.(310±23) min,t=5.049,P=0.000],2组清扫淋巴结个数、术后引流量及并发症

  8. Dynamical theory of spin relaxation

    Science.gov (United States)

    Field, Timothy R.; Bain, Alex D.

    2013-02-01

    The dynamics of a spin system is usually calculated using the density matrix. However, the usual formulation in terms of the density matrix predicts that the signal will decay to zero, and does not address the issue of individual spin dynamics. Using stochastic calculus, we develop a dynamical theory of spin relaxation, the origins of which lie in the component spin fluctuations. This entails consideration of random pure states for individual protons, and how these pure states are correctly combined when the density matrix is formulated. Both the lattice and the spins are treated quantum mechanically. Such treatment incorporates both the processes of spin-spin and (finite temperature) spin-lattice relaxation. Our results reveal the intimate connections between spin noise and conventional spin relaxation.

  9. Supermassive black hole spin-flip during the inspiral

    Energy Technology Data Exchange (ETDEWEB)

    Gergely, Laszlo A [Department of Theoretical Physics, University of Szeged (Hungary); Biermann, Peter L [MPI for Radioastronomy, Bonn (Germany); Caramete, Laurentiu I, E-mail: gergely@physx.u-szeged.h, E-mail: plbiermann@mpifr-bonn.mpg.d, E-mail: lcaramete@gmail.co [Institute for Space Sciences, Bucharest (Romania)

    2010-10-07

    During post-Newtonian evolution of a compact binary, a mass ratio {nu} different from 1 provides a second small parameter, which can lead to unexpected results. We present a statistics of supermassive black hole candidates, which enables us first to derive their mass distribution, and then to establish a logarithmically even probability in {nu} of the mass ratios at their encounter. In the mass ratio range {nu} in (1/30, 1/3) of supermassive black hole mergers representing 40% of all possible cases, the combined effect of spin-orbit precession and gravitational radiation leads to a spin-flip of the dominant spin during the inspiral phase of the merger. This provides a mechanism for explaining a large set of observations on X-shaped radio galaxies. In another 40% with mass ratios {nu} in (1/30, 1/1000) a spin-flip never occurs, while in the remaining 20% of mergers with mass ratios {nu} in (1/3, 1) it may occur during the plunge. We analyze the magnitude of the spin-flip angle occurring during the inspiral as a function of the mass ratio and original relative orientation of the spin and orbital angular momentum. We also derive a formula for the final spin at the end of the inspiral in this mass ratio range.

  10. Litter-Spinning Retarders

    Science.gov (United States)

    Wilson, John C.

    1995-01-01

    Aerodynamic plates stop litter from spinning during hoisting by helicopter. Features of proposed litter-spinning retarders include convenience of deployment and independence from ground restraint. Retarder plate(s) folded flat against bottom of litter during storage or while litter is loaded. Plate(s) held in storage position by latch that releases manually or automatically as litter is hoisted. Upon release, springs move plates into deployed position.

  11. Spin polarizability of hyperons

    Indian Academy of Sciences (India)

    K B Vijaya Kumar

    2014-11-01

    We review the recent progress of the theoretical understanding of spin polarizabilities of the hyperon in the framework of (3) heavy baryon chiral perturbation theory (HBChPT). We present the results of a systematic leading-order calculation of hyperon Compton scattering and extract the forward spin polarizability (0) of hyperons. The results obtained for $_0$ in the case of nucleons agree with the known results of (2) HBChPT when kaon loops are not considered.

  12. Spin transport in nanoscale spin valves and magnetic tunnel junctions

    Science.gov (United States)

    Patibandla, Sridhar

    Spintronics or electronics that utilizes the spin degree of freedom of a single charge carrier (or an ensemble of charge carriers) to store, process, sense or communicate data and information is a rapidly burgeoning field in electronics. In spintronic devices, information is encoded in the spin polarization of a single carrier (or multiple carriers) and the spin(s) of these carrier(s) are manipulated for device operation. This strategy could lead to devices with low power consumption. This dissertation investigates spin transport in one dimensional and two dimensional semiconductors, with a view to applications in spintronic devices. This dissertation is arranged as follows: Chapter 1 gives a detailed introduction and necessary background to understand aspects of spin injection into a semiconductor from a spin polarized source such as a ferromagnet, and spin polarized electron transport in the semiconductor. Chapter 2 discusses the nanoporous alumina technique that is employed to fabricate nanowires and nanowire spin valves for the investigation of spin transport in 1D semiconductors. Chapter 3 investigates the spin transport in quasi one-dimensional spin valves with germanium spacer layer. These spin valves with 50nm in diameter and 1 mum length were fabricated using the porous alumina technique. Spin transport in nanoscale germanium spin valves was demonstrated and the spin relaxation lengths and the spin relaxation times were calculated. Chapter 4 discusses spin transport studies conducted in bulk high purity germanium with a view to comparing spin relaxation mechanisms in low mobility nanowires and high mobility bulk structures. Lateral spin valve with tunnel injectors were employed in this study and the spin transport measurements were conducted at various temperatures. The spin relaxation rates were measured as a function of temperature which allowed us to distinguish between two different mechanisms---D'yakonov-Perel' and Elliott-Yafet---that dominate spin

  13. Bipolar plasma vaporization versus monopolar TUR and “cold-knife" TUI in secondary bladder neck sclerosis – An evidence based, retrospective critical comparison in a single center clinical setting

    Science.gov (United States)

    Moldoveanu, C; Geavlete, B; Jecu, M; Stanescu, F; Adou, L; Bulai, C; Ene, C; Geavlete, P

    2014-01-01

    Introduction: A long term, retrospective study was performed aiming to outline a critical comparison concerning the efficacy, safety and durability of the bipolar plasma vaporization (BPV), standard monopolar transurethral resection (TUR) and “cold-knife" “star" transurethral incision (TUI) in secondary bladder neck sclerosis (BNS) cases. Materials & Methods: Of the 126 patients included in the trial based on maximum flow rate (Qmax) below 10 mL/s and International Prostate Symptom Score (IPSS) over 19, classical resection was performed in 46 cases, “cold-knife" TUI in 37 cases and bipolar vaporization in 43 patients. The evaluation protocol comprised IPSS, QoL (quality of life) score, Qmax and PVR (post-voiding residual urinary volume) assessment performed at 1, 3, 6, 12, 18 and 24 months after the initial intervention. Results: Significant intraoperative complications (capsular perforation – 8.7%; bleeding – 4.3%) occurred secondary to monopolar resection. “Star" TUI was the fastest technique, followed by plasma-button vaporization (7.2 and 11.4 versus 16.5 minutes). BPV and TUI patients benefitted from the shortest catheterization periods (0.75 and 1 versus 2.0 days) and hospital stays (1.0 and 1.25 versus 2.0 days). Immediate postoperative adverse events consisted of hematuria (6.5% of the TUR cases) and acute urinary retention (8.1% of the TUI group). Significantly higher long term BNS recurrence rates requiring re-treatment were established in the TUI (18.7%) and TUR (12.8%) series by comparison to BPV (5.4%). Among patients that completed the follow-up protocol, equivalent IPSS, QoL, Qmax and PVR features were determined in the 3 study arms. Conclusions: The plasma vaporization approach was confirmed as a successful match to conventional TUR and “cold-knife" TUI in terms of surgical safety profile, postoperative recovery, therapeutic durability and urodynamic and symptom score parameters. PMID:24653766

  14. Spin Hall effect induced spin transfer through an insulator

    Science.gov (United States)

    Chen, Wei; Sigrist, Manfred; Manske, Dirk

    2016-09-01

    When charge current passes through a normal metal that exhibits the spin Hall effect, spin accumulates at the edge of the sample in the transverse direction. We predict that this spin accumulation, or spin voltage, enables quantum tunneling of spin through an insulator or vacuum to reach a ferromagnet without transferring charge. In a normal metal/insulator/ferromagnetic insulator trilayer (such as Pt/oxide/YIG), the quantum tunneling explains the spin-transfer torque and spin pumping that exponentially decay with the thickness of the insulator. In a normal metal/insulator/ferromagnetic metal trilayer (such as Pt/oxide/Co), the spin transfer in general does not decay monotonically with the thickness of the insulator. Combining with the spin Hall magnetoresistance, this tunneling mechanism points to the possibility of a tunneling spectroscopy that can probe the magnon density of states of a ferromagnetic insulator in an all-electrical and noninvasive manner.

  15. Spin photonics and spin-photonic devices with dielectric metasurfaces

    CERN Document Server

    Liu, Yachao; Ke, Yougang; Zhou, Xinxing; Luo, Hailu; Wen, Shuangchun

    2015-01-01

    Dielectric metasurfaces with spatially varying birefringence and high transmission efficiency can exhibit exceptional abilities for controlling the photonic spin states. We present here some of our works on spin photonics and spin-photonic devices with metasurfaces. We develop a hybrid-order Poincare sphere to describe the evolution of spin states of wave propagation in the metasurface. Both the Berry curvature and the Pancharatnam-Berry phase on the hybrid-order Poincare sphere are demonstrated to be proportional to the variation of total angular momentum. Based on the spin-dependent property of Pancharatnam-Berry phase, we find that the photonic spin Hall effect can be observed when breaking the rotational symmetry of metasurfaces. Moreover, we show that the dielectric metasurfaces can provide great flexibility in the design of novel spin-photonic devices such as spin filter and spin-dependent beam splitter.

  16. 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.

  17. Ballistic Spin Hall Transistor Using a Heterostructure Channel and Its Application to Logic Devices

    Science.gov (United States)

    Choi, Won Young; Kim, Hyung-Jun; Chang, Joonyeon; Han, Suk Hee; Koo, Hyun Cheol

    2017-07-01

    In a ballistic spin transport channel, spin Hall and Rashba effects are utilized to provide a gate-controlled spin Hall transistor. A ferromagnetic electrode and a spin Hall probe are employed for spin injection and detection, respectively, in a two-dimensional Rashba system. We utilize the spin current of which polarization direction is controlled by the gate electric field which determines the strength of the Rashba effective field. By observing the spin Hall voltage, spin injection and coherent spin precession are electrically monitored. From the original Datta-Das technique, we measure the channel conductance oscillation as the gate voltage is varied. When the magnetization orientation of the injector is reversed by 180°, the phase of the Datta-Das oscillation shifts by 180° as expected. Depending on the magnetization direction, the spin Hall transistor behaves as an n- or p-type transistor. Thus, we can implement the complementary transistors which are analogous to the conventional complementary metal oxide semiconductor transistors. Using the experimental data extracted from the spin Hall transistor, the logic operation is also presented.

  18. Ballistic Spin Hall Transistor Using a Heterostructure Channel and Its Application to Logic Devices

    Science.gov (United States)

    Choi, Won Young; Kim, Hyung-Jun; Chang, Joonyeon; Han, Suk Hee; Koo, Hyun Cheol

    2016-09-01

    In a ballistic spin transport channel, spin Hall and Rashba effects are utilized to provide a gate-controlled spin Hall transistor. A ferromagnetic electrode and a spin Hall probe are employed for spin injection and detection, respectively, in a two-dimensional Rashba system. We utilize the spin current of which polarization direction is controlled by the gate electric field which determines the strength of the Rashba effective field. By observing the spin Hall voltage, spin injection and coherent spin precession are electrically monitored. From the original Datta-Das technique, we measure the channel conductance oscillation as the gate voltage is varied. When the magnetization orientation of the injector is reversed by 180°, the phase of the Datta-Das oscillation shifts by 180° as expected. Depending on the magnetization direction, the spin Hall transistor behaves as an n- or p-type transistor. Thus, we can implement the complementary transistors which are analogous to the conventional complementary metal oxide semiconductor transistors. Using the experimental data extracted from the spin Hall transistor, the logic operation is also presented.

  19. Virtual Orienteering Game For Smartphones

    OpenAIRE

    Sainio, Kari

    2015-01-01

    Orienteering is a relatively famous sports activity in Nordic countries. Today technology provides attractive means for transition from traditional orienteering to virtual orienteering. Virtual orienteering can be thought as orienteering without using a traditional printed map and compass. On the other hand smartphones contain technology for implementing virtual orienteering. There are different smartphone platforms and types, making application development challenging because several cod...

  20. 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.

  1. Magnetocaloric effect in quantum spin-s chains

    Directory of Open Access Journals (Sweden)

    A. Honecker

    2009-01-01

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

  2. 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.)

  3. Entrepreneurial Orientation and Internationalisation

    DEFF Research Database (Denmark)

    Decker, Arnim; Rollnik-Sadowska, Ewa; Servais, Per

    Entrepreneurial orientation is a multidimensional construct that determines the strategic posture of a firm. In this study we investigate a sample of six manufacturing firms which are located both in a remote area and in a transition economy. Through interpreting the construct of entrepreneurial...... orientation as an attitude held by principals we investigate how entrepreneurial orientation affected the behaviour of these firms, specifically in terms of their internationalisation. Despite the fact that all firms have identical roots we find that entrepreneurial orientation held by their principals affect...

  4. Spin polarization phenomena in dense neutron matter at a strong magnetic field

    CERN Document Server

    Isayev, A A

    2010-01-01

    Spin polarized states in neutron matter at strong magnetic fields up to $10^{18}$ G are considered in the model with the Skyrme effective interaction. Analyzing the self-consistent equations at zero temperature, it is shown that a thermodynamically stable branch of solutions for the spin polarization parameter as a function of density corresponds to the negative spin polarization when the majority of neutron spins are oriented oppositely to the direction of the magnetic field. Besides, it is found that in a strong magnetic field the state with the positive spin polarization can be realized as a metastable state at the high density region in neutron matter. At finite temperature, the entropy of the thermodynamically stable branch demonstrates the unusual behavior being larger than that for the nonpolarized state (at vanishing magnetic field) above certain critical density which is caused by the dependence of the entropy on the effective masses of neutrons in a spin polarized state.

  5. Perturbation Method for Classical Spinning Particle Motion: I. Kerr Space-Time

    CERN Document Server

    Singh, Dinesh

    2008-01-01

    This paper presents an analytic perturbation approach to the dynamics of a classical spinning particle, according to the Mathisson-Papapetrou-Dixon (MPD) equations of motion, with a direct application to circular motion around a Kerr black hole. The formalism is established in terms of a power series expansion with respect to the particle's spin magnitude, where the particle's kinematic and dynamical degrees are expressed in a completely general form that can be constructed to infinite order in the expansion parameter. It is further shown that the particle's squared mass and spin magnitude can shift due to a classical analogue of radiative corrections that arise from spin-curvature coupling. Explicit expressions are determined for the case of circular motion near the event horizon a Kerr black hole, where the mass and spin shift contributions are dependent on the initial conditions of the particle's spin orientation. A preliminary analysis of the stability properties of the orbital motion in the Kerr backgrou...

  6. Fredkin Spin Chain

    CERN Document Server

    Salberger, Olof

    2016-01-01

    We introduce a new model of interacting spin 1/2. It describes interaction of three nearest neighbors. The Hamiltonian can be expressed in terms of Fredkin gates. The Fredkin gate (also known as the CSWAP gate) is a computational circuit suitable for reversible computing. Our construction generalizes the work of Ramis Movassagh and Peter Shor. Our model can be solved by means of Catalan combinatorics in the form of random walks on the upper half of a square lattice [Dyck walks]. Each Dyck path can be mapped to a wave function of the spins. The ground state is an equally weighted superposition of Dyck walks [instead of Motzkin walks]. We can also express it as a matrix product state. We further construct the model of interacting spins 3/2 and greater half-integer spins. The models with higher spins require coloring of Dyck walks. We construct SU(k) symmetric model [here k is the number of colors]. The leading term of the entanglement entropy is then proportional to the square root of the length of the lattice ...

  7. The influence of the extraction process and spinning conditions on morphology and ultimate properties of gel-spun polyethylene fibres

    NARCIS (Netherlands)

    Hoogsteen, W.; Brinke, G. ten; Pennings, A.J.

    1987-01-01

    The morphology of gel-spun polyethylene fibres prior to hot-drawing, depends on the spinning conditions and the extraction process. Paraffin oil containing fibres spun at relatively low spin temperatures and high take-up speeds show a c-axis orientation parallel to the fibre axis due to shish-kebab

  8. Quantum-well thickness dependence of spin polarization of excitons

    Directory of Open Access Journals (Sweden)

    M. Idrish Miah

    2011-07-01

    Full Text Available The optical orientation of exciton spins in semiconductor quantum wells (SQWs was investigated by observing the circular polarization of the photoluminescence (PL. The left/right circularly polarized PL in SQWs was measured. It was found that there is a difference between the two different polarization conditions, which is caused by spin-dependent phase-space filling. The PL polarization was estimated from the signals of the left and right circularly polarized PL and was found to depend on the well thickness of SQWs as well as on the sample temperature. The influence of an electric field on the PL polarization was studied.

  9. Superconducting spin-triplet-MRAM with infinite magnetoresistance ratio

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Daniel; Ullrich, Aladin; Obermeier, Guenter; Mueller, Claus; Krug von Nidda, Hans-Albrecht; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation); Zdravkov, Vladimir I. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Institute of Applied Physics and Interdisciplinary Nanoscience Center, Universitaet Hamburg, Jungiusstrasse 9A, D-20355 Hamburg (Germany); Sidorenko, Anatoli S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Tagirov, Lenar R. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation)

    2016-07-01

    We fabricated a nanolayered hybrid superconductor-ferromagnet spin-valve structure, i.e. the superconducting transition temperature of this structure depends on its magnetic history. The observed spin-valve effect is based on the generation of the long range odd in frequency triplet component, arising from a non-collinear relative orientation of the constituent ferromagnetic layers. We investigated the effect both as a function of the sweep amplitude of the magnetic field, determining the magnetic history, and the applied transport current. Moreover, we demonstrate the possibility of switching the system from the normal o the superconducting state by applying field pulses, yielding an infinite magnetoresistance ratio.

  10. Spin-polarized photoemission from SiGe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A.; Bottegoni, F.; Isella, G.; Cecchi, S.; Chrastina, D.; Finazzi, M.; Ciccacci, F. [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2013-12-04

    We apply the principles of Optical Orientation to measure by Mott polarimetry the spin polarization of electrons photoemitted from different group-IV heterostructures. The maximum measured spin polarization, obtained from a Ge/Si{sub 0.31}Ge{sub 0.69} strained film, undoubtedly exceeds the maximum value of 50% attainable in bulk structures. The explanation we give for this result lies in the enhanced band orbital mixing between light hole and split-off valence bands as a consequence of the compressive strain experienced by the thin Ge layer.

  11. Computational Hardness of Enumerating Satisfying Spin-Assignments in Triangulations

    CERN Document Server

    Jiménez, Andrea

    2011-01-01

    Satisfying spin-assignments in triangulations of a surface are states of minimum energy of the antiferromagnetic Ising model on triangulations which correspond (via geometric duality) to perfect matchings in cubic bridgeless graphs. In this work we show that it is NP-complete to decide whether or not a surface triangulation admits a satisfying spin-assignment, and that it is #P-complete to determine the number of such assignments. Both results are derived via an elaborate (and atypical) reduction that maps a Boolean formula in 3-conjunctive normal form into a triangulation of an orientable closed surface.

  12. Spin Structures in Magnetic Nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Brok, Erik; Frandsen, Cathrine

    2013-01-01

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

  13. Electrical detection of the spin resonance of a single electron in a silicon field-effect transistor.

    Science.gov (United States)

    Xiao, M; Martin, I; Yablonovitch, E; Jiang, H W

    2004-07-22

    The ability to manipulate and monitor a single-electron spin using electron spin resonance is a long-sought goal. Such control would be invaluable for nanoscopic spin electronics, quantum information processing using individual electron spin qubits and magnetic resonance imaging of single molecules. There have been several examples of magnetic resonance detection of a single-electron spin in solids. Spin resonance of a nitrogen-vacancy defect centre in diamond has been detected optically, and spin precession of a localized electron spin on a surface was detected using scanning tunnelling microscopy. Spins in semiconductors are particularly attractive for study because of their very long decoherence times. Here we demonstrate electrical sensing of the magnetic resonance spin-flips of a single electron paramagnetic spin centre, formed by a defect in the gate oxide of a standard silicon transistor. The spin orientation is converted to electric charge, which we measure as a change in the source/drain channel current. Our set-up may facilitate the direct study of the physics of spin decoherence, and has the practical advantage of being composed of test transistors in a conventional, commercial, silicon integrated circuit. It is well known from the rich literature of magnetic resonance studies that there sometimes exist structural paramagnetic defects near the Si/SiO2 interface. For a small transistor, there might be only one isolated trap state that is within a tunnelling distance of the channel, and that has a charging energy close to the Fermi level.

  14. 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.

  15. Spin rectification induced by spin Hall magnetoresistance at room temperature

    Science.gov (United States)

    Wang, P.; Jiang, S. W.; Luan, Z. Z.; Zhou, L. F.; Ding, H. F.; Zhou, Y.; Tao, X. D.; Wu, D.

    2016-09-01

    We have experimentally and theoretically investigated the dc voltage generation in the heterostructure of Pt and yttrium iron garnet under the ferromagnetic resonance. Besides a symmetric Lorenz line shape dc voltage, an antisymmetric Lorenz line shape dc voltage is observed in field scan, which can solely originate from the spin rectification effect due to the spin Hall magnetoresistance. The angular dependence of the dc voltage is theoretically analyzed by taking into account both the spin pumping and the spin rectification effects. We find that the experimental results are in excellent agreement with the theoretical model, further identifying the spin Hall magnetoresistance origin of the spin rectification effect. Moreover, the spin pumping and the spin rectification effects are quantitatively separated by their different angular dependence at particular experimental geometry.

  16. Spin filter and spin valve in ferromagnetic graphene

    Science.gov (United States)

    Song, Yu; Dai, Gang

    2015-06-01

    We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter and a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.

  17. Spin-Orbit Twisted Spin Waves: Group Velocity Control

    Science.gov (United States)

    Perez, F.; Baboux, F.; Ullrich, C. A.; D'Amico, I.; Vignale, G.; Karczewski, G.; Wojtowicz, T.

    2016-09-01

    We present a theoretical and experimental study of the interplay between spin-orbit coupling (SOC), Coulomb interaction, and motion of conduction electrons in a magnetized two-dimensional electron gas. Via a transformation of the many-body Hamiltonian we introduce the concept of spin-orbit twisted spin waves, whose energy dispersions and damping rates are obtained by a simple wave-vector shift of the spin waves without SOC. These theoretical predictions are validated by Raman scattering measurements. With optical gating of the density, we vary the strength of the SOC to alter the group velocity of the spin wave. The findings presented here differ from that of spin systems subject to the Dzyaloshinskii-Moriya interaction. Our results pave the way for novel applications in spin-wave routing devices and for the realization of lenses for spin waves.

  18. Semiclassical spin transport in spin-orbit-coupled bands.

    Science.gov (United States)

    Culcer, Dimitrie; Sinova, Jairo; Sinitsyn, N A; Jungwirth, T; MacDonald, A H; Niu, Q

    2004-07-23

    Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in which the average spin is transported at the wave packet group velocity, the spin current has additional contributions from the wave packet's spin and torque dipole moments. Electric field corrections to the group velocity and carrier spin contribute to the convective term. Summing all terms we obtain an expression for the intrinsic spin-Hall conductivity of a hole-doped semiconductor, which agrees with the Kubo formula prediction for the same quantity. We discuss the calculation of spin accumulation, which illustrates the importance of the torque dipole near the boundary of the system.

  19. 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

  20. 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.

    2016-10-01

    Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements.

  1. Paramagnetic Spin Seebeck Effect

    Science.gov (United States)

    Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand

    2015-05-01

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20 K ), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  2. Higher-spin correlators

    CERN Document Server

    Alday, Luis F

    2013-01-01

    We analyze the properly normalized three-point correlator of two protected scalar operators and one higher spin twist-two operator in N=4 super Yang-Mills, in the limit of large spin j. The relevant structure constant can be extracted from the OPE of the four-point correlator of protected scalar operators. We show that crossing symmetry of the four point correlator plus a judicious guess for the perturbative structure of the three-point correlator, allow to make a prediction for the structure constant at all loops in perturbation theory, up to terms that remain finite as the spin becomes large. Furthermore, the expression for the structure constant allows to propose an expression for the all loops four-point correlator G(u,v), in the limit u,v -> 0. Our predictions are in perfect agreement with the large j expansion of results available in the literature.

  3. 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.

  4. Exertional Rhabdomyolysis after Spinning.

    Science.gov (United States)

    Jeong, Youjin; Kweon, Hyuk-Jung; Oh, Eun-Jung; Ahn, Ah-Leum; Choi, Jae-Kyung; Cho, Dong-Yung

    2016-11-01

    Any strenuous muscular exercise may trigger rhabdomyolysis. We report an episode of clinically manifested exertional rhabdomyolysis due to stationary cycling, commonly known as spinning. Reports of spinning-related rhabdomyolysis are rare in the English literature, and the current case appears to be the first such case reported in South Korea. A previously healthy 21-year-old Asian woman presented with severe thigh pain and reddish-brown urinary discoloration 24-48 hours after attending a spinning class at a local gymnasium. Paired with key laboratory findings, her symptoms were suggestive of rhabdomyolysis. She required hospital admission to sustain renal function through fluid resuscitation therapy and fluid balance monitoring. Because exertional rhabdomyolysis may occur in any unfit but otherwise healthy individual who indulges in stationary cycling, the potential health risks of this activity must be considered.

  5. 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.

  6. Perspectives on spin glasses

    CERN Document Server

    Contucci, Pierluigi

    2013-01-01

    Presenting and developing the theory of spin glasses as a prototype for complex systems, this book is a rigorous and up-to-date introduction to their properties. The book combines a mathematical description with a physical insight of spin glass models. Topics covered include the physical origins of those models and their treatment with replica theory; mathematical properties like correlation inequalities and their use in the thermodynamic limit theory; main exact solutions of the mean field models and their probabilistic structures; and the theory of the structural properties of the spin glass phase such as stochastic stability and the overlap identities. Finally, a detailed account is given of the recent numerical simulation results and properties, including overlap equivalence, ultrametricity and decay of correlations. The book is ideal for mathematical physicists and probabilists working in disordered systems.

  7. Sexual Orientation and Choice

    Directory of Open Access Journals (Sweden)

    Ayala Saray

    2017-07-01

    Full Text Available Is there a choice in sexual orientation? [Wilkerson, William S. (2009: “Is It a Choice? Sexual Orientation as Interpretation”. In: Journal of Social Philosophy 40. No. 1, p. 97–116] argues that sexual desires require interpretation in order to be fully constituted, and therefore sexual orientation is at least partially constituted by choice. [Díaz-León, Esa (2017: “Sexual Orientation as Interpretation? Sexual Desires, Concepts, and Choice”; In: Journal of Social Ontology] critically assesses Wilkerson’s argument, concluding that we still lack a good argument for the claim that choice plays a role in sexual orientation. Here I examine Díaz-León’s response to Wilkerson. I introduce what I call the conceptual act theory of sexual orientation, and argue that even if interpretation were not necessary to constitute sexual desires, it is a necessary element to constitute what we call sexual orientation. However, I conclude that even if we agree that interpretation is involved in sexual orientation, it does not follow that there is a choice involved.

  8. Edward Said and "Orientalism"

    Science.gov (United States)

    Chronicle of Higher Education, 2007

    2007-01-01

    In the nearly 30 years since Edward Said published the hugely influential Orientalism, his indictment of racism and imperialism in Western scholarship on the Orient has had its share of plaudits and condemnations. Now Robert Irwin, the Middle East editor of The Times Literary Supplement, has reignited the controversy with his broadside against the…

  9. Orientalism/Occidentalism

    NARCIS (Netherlands)

    Minca, C.; Ong, C.E.

    2017-01-01

    Orientalism and Occidentalism are interrelated concepts. Orientalism is defined in three keys ways: (i) as a study of “the Orient”; (ii) as a cultural and aesthetic concern with “the Orient”; and (iii) as a critical approach to understanding the construction of “the Orient” by European and American

  10. Teaching Orienteering. Second Edition.

    Science.gov (United States)

    McNeill, Carol; Cory-Wright, Jean; Renfrew, Tom

    The educational value provided by orienteering's blend of navigational and physical skills has given it a permanent place in the primary and secondary school curriculum in the United Kingdom. This book is a reference to orienteering for teachers, leaders, and coaches. It provides a "how to" approach to introducing and developing the…

  11. Orienteering in Camping.

    Science.gov (United States)

    Larson, Elston F.

    One of the recent developments in camping is "orienteering", a program using a map and compass. Orienteering can be dovetailed into an overall camping program and used to "point up" the entire program, or it can be confined to a single simple game. The arrangement depends on the situation. The minimum age of the participants should be about 9 or…

  12. Decision Making In Orienteering.

    Science.gov (United States)

    Almeida, Katia

    1997-01-01

    Eight psychometric instruments were administered to 10 elite male Portuguese orienteers. The cognitive process involved in decision making did not differ between the best orienteers and the others. This group of athletes had a high capacity for work realization and a strong need to be in control of interpersonal situations. (Author/SV)

  13. Wildlife value orientations

    DEFF Research Database (Denmark)

    Gamborg, Christian; Jensen, Frank Søndergaard

    2016-01-01

    This article examined value orientations toward wildlife among the adult general Danish public in relation to age, sex, past and present residence, education, and income, using a U.S. survey instrument on Wildlife Value Orientations (WVO). The study used an Internet-based questionnaire sent...

  14. Zero-bias spin separation

    Science.gov (United States)

    Ganichev, Sergey D.; Bel'Kov, Vasily V.; Tarasenko, Sergey A.; Danilov, Sergey N.; Giglberger, Stephan; Hoffmann, Christoph; Ivchenko, Eougenious L.; Weiss, Dieter; Wegscheider, Werner; Gerl, Christian; Schuh, Dieter; Stahl, Joachim; de Boeck, Jo; Borghs, Gustaaf; Prettl, Wilhelm

    2006-09-01

    The generation, manipulation and detection of spin-polarized electrons in low-dimensional semiconductors are at the heart of spintronics. Pure spin currents, that is, fluxes of magnetization without charge current, are quite attractive in this respect. A paradigmatic example is the spin Hall effect, where an electrical current drives a transverse spin current and causes a non-equilibrium spin accumulation observed near the sample boundary. Here we provide evidence for an another effect causing spin currents which is fundamentally different from the spin Hall effect. In contrast to the spin Hall effect, it does not require an electric current to flow: without bias the spin separation is achieved by spin-dependent scattering of electrons in media with suitable symmetry. We show, by free-carrier absorption of terahertz (THz) radiation, that spin currents flow in a wide range of temperatures. Moreover, the experimental results provide evidence that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy-relaxation processes.

  15. Fabrication of ?-Carrageenan Fibers by Wet Spinning: Spinning Parameters

    OpenAIRE

    Lingyan Kong; Gregory R. Ziegler

    2011-01-01

    This study demonstrates the fabrication of κ-carrageenan fibers by a wet-spinning method and discusses three important spinning parameters: coagulation bath composition, spinning rate and post-spinning mechanical drawing. The as-spun fiber diameter decreased with KCl and ethanol concentration in the coagulation bath. In general, the ultimate tensile stress and elongation at break both increased for KCl concentration from 0.1 to 0.5 M with and without ethanol, with no significant change above ...

  16. Spin wave confinement

    CERN Document Server

    2008-01-01

    This book presents recent scientific achievements in the investigation of magnetization dynamics in confined magnetic systems. Introduced by Bloch as plane waves of magnetization in unconfined ferromagnets, spin waves currently play an important role in the description of very small magnetic systems ranging from microelements, which form the basis of magnetic sensors, to magnetic nano-contacts. The spin wave confinement effect was experimentally discovered in the 1990s in permalloy microstripes. The diversity of systems where this effect is observed has been steadily growing since then, and

  17. The Transverse Spin

    CERN Document Server

    Artru, X

    2002-01-01

    Contents : 1. Pre-history 2. Transversity versus helicity 3. The massless limit. "Cardan" and "see-saw" transformations 4. Transversity distribution delta q(x). The diquark spectator model 5. Soffer inequality 6. Tensor charge sum rule 7. t-channel analysis 8. Selection rules for delta q(x) measurements 9. Evolution with Q squared 10. Quark polarimetry. The sheared-jet (Collins) effect 11. Single-spin asymmetries in inclusive experiments 12. Quark distribution dependent on both spin and transverse momentum 13. First evidence of quark transversity

  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. Spin echo in synchrotrons

    Science.gov (United States)

    Chao, Alexander W.; Courant, Ernest D.

    2007-01-01

    As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency Δνspin of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time τ between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference-overlap effect and a spin echo effect. This paper is to address these two effects. The interference-overlap effect occurs when Δνspin is too small, or when τ is too short, to complete the smearing process. In this case, the two resonance crossings overlap each other, and the final polarization exhibits constructive or destructive interference patterns depending on the exact value of τ. Typically, the beam’s energy spread is large and this interference-overlap effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time τ after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when τ is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving an analysis

  20. Spin Echo in Synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alexander W.; /SLAC; Courant, Ernest D.; /Brookhaven

    2006-12-01

    As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency {Delta}{nu}{sub spin} of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time {tau} between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference effect and a spin echo effect. This paper is to address these two effects. The interference effect occurs when {Delta}{nu}{sub spin} is too small, or when {tau} is too short, to complete the smearing process. In this case, the two resonance crossings interfere with each other, and the final polarization exhibits constructive or destructive patterns depending on the exact value of {tau}. Typically, the beam's energy spread is large and this interference effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time {tau} after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when {tau} is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving

  1. Four-Dimensional Spin Foam Perturbation Theory

    Directory of Open Access Journals (Sweden)

    João Faria Martins

    2011-10-01

    Full Text Available We define a four-dimensional spin-foam perturbation theory for the BF-theory with a B∧B potential term defined for a compact semi-simple Lie group G on a compact orientable 4-manifold M. This is done by using the formal spin foam perturbative series coming from the spin-foam generating functional. We then regularize the terms in the perturbative series by passing to the category of representations of the quantum group U_q(g where g is the Lie algebra of G and q is a root of unity. The Chain-Mail formalism can be used to calculate the perturbative terms when the vector space of intertwiners Λ⊗Λ→A, where A is the adjoint representation of g, is 1-dimensional for each irrep Λ. We calculate the partition function Z in the dilute-gas limit for a special class of triangulations of restricted local complexity, which we conjecture to exist on any 4-manifold M. We prove that the first-order perturbative contribution vanishes for finite triangulations, so that we define a dilute-gas limit by using the second-order contribution. We show that Z is an analytic continuation of the Crane-Yetter partition function. Furthermore, we relate Z to the partition function for the F∧F theory.

  2. Coherent spin mixing dynamics in thermal $^{87}$Rb spin-1 and spin-2 gases

    CERN Document Server

    He, Xiaodong; Li, Xiaoke; Wang, Fudong; Xu, Zhifang; Wang, Dajun

    2015-01-01

    We study the non-equilibrium coherent spin mixing dynamics in ferromagnetic spin-1 and antiferromagnetic spin-2 thermal gases of ultracold $^{87}$Rb atoms. Long lasting spin population oscillations with magnetic field dependent resonances are observed in both cases. Our observations are well reproduced by Boltzmann equations of the Wigner distribution function. Compared to the equation of motion of spinor Bose-Einstein condensates, the only difference here is a factor of two increase in the spin-dependent interaction, which is confirmed directly in the spin-2 case by measuring the relation between the oscillation amplitude and the sample's density.

  3. Spin Caloritronic Phenomena Driven by Spin-orbit Coupling

    NARCIS (Netherlands)

    Chen, Y.-T.

    2014-01-01

    In this thesis, we report several effects in spintronics and spin caloritronics related to relativistic spin-orbit coupling. In Chapter 2, we discuss the relativistic spin caloritronicHall effects in terms of a semiclassical theory for anomalous thermoelectric effects in ferromagnetic metals due to

  4. Spin injection and perpendicular spin transport in graphite nanostructures

    NARCIS (Netherlands)

    Banerjee, T.; van der Wiel, Wilfred Gerard; Jansen, R.

    2010-01-01

    Organic- and carbon-based materials are attractive for spintronics because their small spin-orbit coupling and low hyperfine interaction is expected to give rise to large spin-relaxation times. However, the corresponding spin-relaxation length is not necessarily large when transport is via weakly

  5. Junction conditions in General Relativity with spin sources

    CERN Document Server

    Giacomini, A; Willison, S; Giacomini, Alex; Troncoso, Ricardo; Willison, Steven

    2006-01-01

    The junction conditions for General Relativity in the presence of domain walls with intrinsic spin are derived in three and higher dimensions. A stress tensor and a spin current can be defined just by requiring the existence of a well defined volume element instead of an induced metric, so as to allow for generic torsion sources. In general, when the torsion is localized on the domain wall, it is necessary to relax the continuity of the tangential components of the vielbein. In fact it is found that the spin current is proportional to the jump in the vielbein and the stress-energy tensor is proportional to the jump in the spin connection. The consistency of the junction conditions implies a constraint between the direction of flow of energy and the orientation of the spin. As an application, we derive the circularly symmetric solutions for both the rotating string with tension and the spinning dust string in three dimensions. The rotating string with tension generates a rotating truncated cone outside and a f...

  6. Uniform spinning sampling gradient electron paramagnetic resonance imaging.

    Science.gov (United States)

    Johnson, David H; Ahmad, Rizwan; Liu, Yangping; Chen, Zhiyu; Samouilov, Alexandre; Zweier, Jay L

    2014-02-01

    To improve the quality and speed of electron paramagnetic resonance imaging (EPRI) acquisition by combining a uniform sampling distribution with spinning gradient acquisition. A uniform sampling distribution was derived for spinning gradient EPRI acquisition (uniform spinning sampling, USS) and compared to the existing (equilinear spinning sampling, ESS) acquisition strategy. Novel corrections were introduced to reduce artifacts in experimental data. Simulations demonstrated that USS puts an equal number of projections near each axis whereas ESS puts excessive projections at one axis, wasting acquisition time. Artifact corrections added to the magnetic gradient waveforms reduced noise and correlation between projections. USS images had higher SNR (85.9 ± 0.8 vs. 56.2 ± 0.8) and lower mean-squared error than ESS images. The quality of the USS images did not vary with the magnetic gradient orientation, in contrast to ESS images. The quality of rat heart images was improved using USS compared to that with ESS or traditional fast-scan acquisitions. A novel EPRI acquisition which combines spinning gradient acquisition with a uniform sampling distribution was developed. This USS spinning gradient acquisition offers superior SNR and reduced artifacts compared to prior methods enabling potential improvements in speed and quality of EPR imaging in biological applications. Copyright © 2013 Wiley Periodicals, Inc.

  7. Organic semiconductors: What makes the spin relax?

    Science.gov (United States)

    Bobbert, Peter A.

    2010-04-01

    Spin relaxation in organic materials is expected to be slow because of weak spin-orbit coupling. The effects of deuteration and coherent spin excitation show that the spin-relaxation time is actually limited by hyperfine fields.

  8. Bipolar spin-valley diode effect in a silicene magnetic junction

    Science.gov (United States)

    Zhai, Xuechao; Zhang, Sihao; Zhao, Ying; Zhang, Xiaoyu; Yang, Zhihong

    2016-09-01

    Silicene has attracted much attention recently due to the electrons' multiple degrees of freedom, specifically for spin and valley. We here demonstrate that a bipolar spin-valley diode effect can be driven and controlled by applying longitudinal biases through a silicene ferromagnetic-field/interlayer-electric-field junction. This effect indicates that only one-spin (the other spin) electrons from one valley (the other valley) contribute to the conductance under positive (negative) biases, originating from the specific band-matching tunneling mechanism. All the forbidden channels are induced by either spin-mismatch or spin-valley dependent bandgaps. It is also found that, by reversing the direction of interlayer electric field, the conductive valley can be switched to the other while the spin orientation is reserved. Furthermore, all the possible spin-valley configurations of conductance, contributed by single spin and single valley, can be completely turned "on" or "off" only by tuning the bias and the electric field. These results suggest that silicene can be a good candidate for future quantum information processing in spin-valley logic circuits.

  9. Measuring the spin of black holes in binary systems using gravitational waves

    CERN Document Server

    Vitale, Salvatore; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-01-01

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions, and the opportunity of measuring spins directly through GW observations. In this letter we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientation, and signal-to-noise ratio. We find that spin magnitudes and tilt angles can be estimated to accuracy of a few percent for neutron star--black hole systems and $\\sim$ 5-30% for black hole binaries. In contrast, the difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum, and that a sudden change of behavior occurs when a system is observed from ...

  10. Spin-dependent optical superlattice

    Science.gov (United States)

    Yang, Bing; Dai, Han-Ning; Sun, Hui; Reingruber, Andreas; Yuan, Zhen-Sheng; Pan, Jian-Wei

    2017-07-01

    We propose and implement a lattice scheme for coherently manipulating atomic spins. Using a vector light shift and a superlattice structure, we demonstrate experimentally its capability on addressing spins in double wells and square plaquettes with subwavelength resolution. The quantum coherence of spin manipulations is verified through measuring atom tunneling and spin exchange dynamics. Our experiment presents a building block for engineering many-body quantum states in optical lattices for realizing quantum simulation and computation tasks.

  11. Spin Tilts in the Double Pulsar Reveal Off-Center Supernova Kick and Tumble

    CERN Document Server

    Farr, Will M; Lyutikov, Maxim; Kalogera, Vassiliki

    2011-01-01

    The system PSR J0737-3039 is the only binary pulsar known to consist of two radio pulsars (PSR J0737-3039 A and PSR J0737-3039 B). This configuration allows measurements of spin orientation for both pulsars: pulsar A's spin is tilted from the orbital angular momentum by no more than 14 degrees; pulsar B's by 130 degrees. This spin-spin misalignment requires that the origin of most of B's spin is its supernova; the spin could originate from a substantial off-center kick, causing pulsar B to tumble to its misaligned state. Under the typical assumption of an instantaneous kick and using current constraints on the kick magnitude, it must have been displaced from the center of mass of the exploding star by at least 1 km and probably 5--10 km. Regardless of the details of the process that produced pulsar B's current spin, the orientation of the spins in the J0737-3039 system provides a direct, unique constraint on angular momentum production in supernovae.

  12. The typical mass ratio and typical final spin in supermassive black hole mergers

    CERN Document Server

    Gergely, László Á

    2012-01-01

    We prove that merging supermassive black holes (SMBHs) typically have neither equal masses, nor is their mass ratio too extreme. The majority of such mergers fall into the mass ratio range of 1:30 to 1:3, implying a spin flip during the inspiral. We also present a simple expression for the final spin $\\chi_{f}$ of the emerging SMBH, as function of the mass ratio, initial spin magnitudes, and orientation of the spins with respect to the orbital plane and each other. This formula approximates well more cumbersome expressions obtained from the fit with numerical simulations. By integrating over all equally likely orientations for precessing mergers we determine a lower approximant to the final spin distribution as function of the mass ratio alone. By folding this with the derived mass ratio dependent merger rate we derive a lower bound to the typical final spin value after mergers. We repeat the procedure deriving an upper bound for the typical spin in the case when the spins are aligned to the orbital angular m...

  13. Electrical control of spin in topological insulators

    Science.gov (United States)

    Chang, Kai

    2012-02-01

    All-electrical manipulation of electron spin in solids becomes a central issue of quantum information processing and quantum computing. The many previous proposals are based on spin-orbit interactions in semiconductors. Topological insulator, a strong spin-orbit coupling system, make it possible to control the spin transport electrically. Recent calculations proved that external electric fields can drive a HgTe quantum well from normal band insulator phase to topological insulator phase [1]. Since the topological edge states are robust against local perturbation, the controlling of edge states using local fields is a challenging task. We demonstrate that a p-n junction created electrically in HgTe quantum wells with inverted band structure exhibits interesting intraband and interband tunneling processes. We find a perfect intraband transmission for electrons injected perpendicularly to the interface of the p-n junction. The opacity and transparency of electrons through the p-n junction can be tuned by changing the incidence angle, the Fermi energy and the strength of the Rashba spin-orbit interaction (RSOI). The occurrence of a conductance plateau due to the formation of topological edge states in a quasi-one-dimensional p-n junction can be switched on and off by tuning the gate voltage. The spin orientation can be substantially rotated when the samples exhibit a moderately strong RSOI [2]. An electrical switching of the edge-state transport can also be realized using quantum point contacts in quantum spin Hall bars. The switch-on/off of the edge channel is caused by the finite size effect of the quantum point contact and therefore can be manipulated by tuning the voltage applied on the split gate [3,4]. The magnetic ions doped on the surface of 3D TI can be correlated through the helical electrons. The RKKY interaction mediated by the helical Dirac electrons consists of the Heisenberg-like, Ising-like, and Dzyaloshinskii-Moriya (DM)-like terms, which can be tuned

  14. TRANSVERSITY SINGLE SPIN ASYMMETRIES.

    Energy Technology Data Exchange (ETDEWEB)

    BOER,D.

    2001-04-27

    The theoretical aspects of two leading twist transversity single spin asymmetries, one arising from the Collins effect and one from the interference fragmentation functions, are reviewed. Issues of factorization, evolution and Sudakov factors for the relevant observables are discussed. These theoretical considerations pinpoint the most realistic scenarios towards measurements of transversity.

  15. 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.

  16. 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

  17. Layered kagome spin ice

    Science.gov (United States)

    Hamp, James; Dutton, Sian; Mourigal, Martin; Mukherjee, Paromita; Paddison, Joseph; Ong, Harapan; Castelnovo, Claudio

    Spin ice materials provide a rare instance of emergent gauge symmetry and fractionalisation in three dimensions: the effective degrees of freedom of the system are emergent magnetic monopoles, and the extensively many `ice rule' ground states are those devoid of monopole excitations. Two-dimensional (kagome) analogues of spin ice have also been shown to display a similarly rich behaviour. In kagome ice however the ground-state `ice rule' condition implies the presence everywhere of magnetic charges. As temperature is lowered, an Ising transition occurs to a charge-ordered state, which can be mapped to a dimer covering of the dual honeycomb lattice. A second transition, of Kosterlitz-Thouless or three-state Potts type, occurs to a spin-ordered state at yet lower temperatures, due to small residual energy differences between charge-ordered states. Inspired by recent experimental capabilities in growing spin ice samples with selective (layered) substitution of non-magnetic ions, in this work we investigate the fate of the two ordering transitions when individual kagome layers are brought together to form a three-dimensional pyrochlore structure coupled by long range dipolar interactions. We also consider the response to substitutional disorder and applied magnetic fields.

  18. Supramolecular spin valves

    Science.gov (United States)

    Urdampilleta, M.; Klyatskaya, S.; Cleuziou, J.-P.; Ruben, M.; Wernsdorfer, W.

    2011-07-01

    Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc2 single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.

  19. Spin, mass, and symmetry

    CERN Document Server

    Peskin, Michael E

    1994-01-01

    This is a broad-brush introduction to the theory of spin in quantum field theory, presented at the 1993 SLAC Summer Institute. It may be useful for beginning students. (text only; complete paper with figures available by anonymous ftp from preprint.slac.stanford.edu, in the directory pub/preprints/hep-ph/9405)

  20. Polyoxometalates as spin qubits

    Science.gov (United States)

    Gaita-Ariño, A.; Aldamen, M.; Clemente-Juan, J.-M.; Coronado, E.; Lehmann, J.; Loss, D.; Stamp, P.

    2008-03-01

    Polyoxometalates (POMs) are discrete fragments of metal oxides, clusters of regular MOn polyhedra. POMs show a remarkable flexibility in composition, structure and charge state, and thus can be designed according to specific electric and magnetic needs. The two localized spins with S = 1/2 on the V atoms in [PMo12O40(VO)2]^q- can be coupled through the delocalized electrons of the central core. This system was recently used for a theoretical scheme involving two-qubit gates and readout: the electrical manipulation of the molecular redox potential changes the charge of the core and thus the effective magnetic exchange between the qubits. Polyoxometalates can encapsulate magnetic ions, protecting them by a diamagnetic shell of controlled geometry. A great potential of POMs as spin qubits is that they can be constructed using only even elements, such as O, W, Mo and/or Si. Thus, there is a high abundance of polyoxometalate molecules without any nuclear spin, which could result in unusually low decoherence rates. There is currently an effort involving highly anisotropic, high magnetic moment, lanthanide@polyoxometalate molecules acting as spin qubits.

  1. Spin dynamics in general relativity

    NARCIS (Netherlands)

    Saravanan, S.

    2016-01-01

    Since all astrophysical objects spin, it is important to study the dynamics of spinning objects in curved space-time. The dynamics of spinning particles are described with a covariant Hamiltonian formalism. In this formalism, the closed set of equations of motion are obtained from Poisson-Dirac

  2. Mechanical generation of spin current

    Directory of Open Access Journals (Sweden)

    Mamoru eMatsuo

    2015-07-01

    Full Text Available We focus the recent results on spin-current generation from mechanical motion such as rigid rotation and elastic deformations. Spin transport theory in accelerating frames is constructed by using the low energy expansion of the generally covariant Dirac equation. Related issues on spin-manipulation by mechanical rotation are also discussed.

  3. 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 spi

  4. 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.

  5. When measured spin polarization is not spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Dowben, P A; Wu Ning; Binek, Christian, E-mail: pdowben@unl.edu [Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0299 (United States)

    2011-05-04

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

  6. When measured spin polarization is not spin polarization.

    Science.gov (United States)

    Dowben, P A; Wu, Ning; Binek, Christian

    2011-05-04

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO(2) and Cr(2)O(3) illustrate some of the complications which hinders comparisons of spin polarization values. © 2011 IOP Publishing Ltd

  7. Spin-sensitive atom mirror via spin-orbit interaction

    Science.gov (United States)

    Zhou, Lu; Zheng, Ren-Fei; Zhang, Weiping

    2016-11-01

    Based on the spin-orbit coupling recently implemented in a neutral cold-atom gas, we propose a scheme to realize spin-dependent scattering of cold atoms. In particular we consider a matter wave packet of cold-atom gas impinging upon a step potential created by the optical light field, inside of which the atoms are subject to spin-orbit interaction. We show that the proposed system can act as a spin polarizer or spin-selective atom mirror for the incident atomic beam. The principle and the operating parameter regime of the system are carefully discussed.

  8. Towards a new orientation

    DEFF Research Database (Denmark)

    Froulund Jensen, Janet; Overgaard, Dorthe; Bestle, Morten H

    2017-01-01

    narrative of recovery was 'toward a trajectory of new orientation'. This narrative contained the chronological narratives of being 'at death's door', 'still not out of the woods' and 'on the road to recovery'. The road to recovery was described as downhill, steady-state or progressive. New orientation...... was obtained in steady-state or progressive recovery. CONCLUSIONS: This study provides a contemporary understanding of the process of intensive care recovery. Recovery evolves through narratives of mortal danger, risk of relapse and moving forward towards a new orientation in life. RELEVANCE TO CLINICAL...

  9. Developing a market orientation.

    Science.gov (United States)

    Hallums, A

    1994-03-01

    Developing a market-orientated organization is a complex task. An organization's market orientation is reflected in its ability to fulfil its customer's needs. The organization must look outside itself and adopt a flexible response to changing needs. This paper will examine what is meant by the term marketing and why it is necessary for an organization to incorporate the marketing concept. Analysis of the organization's culture and its relevance to the development of market orientation will also be considered. Reference will be made to health care where appropriate.

  10. Inertial effect on spin-orbit coupling and spin transport

    Science.gov (United States)

    Basu, B.; Chowdhury, Debashree

    2013-08-01

    We theoretically study the renormalization of inertial effects on the spin dependent transport of conduction electrons in a semiconductor by taking into account the interband mixing on the basis of k→ṡp→ perturbation theory. In our analysis, for the generation of spin current we have used the extended Drude model where the spin-orbit coupling plays an important role. We predict enhancement of the spin current resulting from the renormalized spin-orbit coupling effective in our model in cubic and non-cubic crystals. Attention has been paid to clarify the importance of gauge fields in the spin transport of this inertial system. A theoretical proposition of a perfect spin filter has been done through the Aharonov-Casher like phase corresponding to this inertial system. For a time dependent acceleration, effect of k→ ṡp→ perturbation on the spin current and spin polarization has also been addressed. Furthermore, achievement of a tunable source of polarized spin current through the non uniformity of the inertial spin-orbit coupling strength has also been discussed.

  11. Two-Dimensional Electron-Spin Resonance

    Science.gov (United States)

    Freed, Jack H.

    2000-03-01

    The extension of the concepts of 2D-NMR to ESR posed significant technological challenges, especially for liquids. ESR relaxation times are very short, as low as 10-15 ns. for T_2's. Spectral bandwidths are 100-250 MHz for nitroxide spin labels. Adequate coverage is obtained with 3-5 ns. π/2 (9-17 GHz) microwave pulses into a small low Q resonator. Dead-times are currently 25-30 ns. Additional requirements are rapid phase shifting for phase cycling, nsec. data acquisition, and fast repetition rates (10-100 kHz). 2D-ELDOR (electron-electron double resonance), which is a 3-pulse 2D-exchange experiment, takes about 30 minutes with just 0.5 nanomole spin-probe in solution (SNR 200). 2D-ELDOR is very useful in studies of molecular dynamics and local structure in complex fluids. For such media, the slow rotational dynamics requires a theory based upon the stochastic Liouville equation which enables quantitative interpretation of 2D-ELDOR experiments. In studies of spin-probes in a liquid crystal new insights could be obtained on the dynamic structure in different phases. One obtains, in addition to ordering and reorientation rates of the probes, details of the local dynamic cage: its orienting potential and (slow) relaxation rate. 2D-ELDOR overcomes the loss of resolution resulting from microscopically ordered but macroscopically disordered complex fluids. This is illustrated by studies of the dynamic structure of lipid membrane vesicles, and the effects of adding a peptide. The short dead times enable the observation of both the bulk lipids and the more immobilized lipids that coat (or are trapped) by the (aggregates of) peptides. Also, new developments of multi-quantum (2D) FT-ESR from nitroxide spin labels interacting by dipolar interactions show considerable promise in measuring distances of ca. 15-70A in macromolecules.

  12. Entanglement Entropy in Random Quantum Spin-S Chains

    CERN Document Server

    Saguia, A; 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.

  13. Spin-optical metamaterial route to spin-controlled photonics.

    Science.gov (United States)

    Shitrit, Nir; Yulevich, Igor; Maguid, Elhanan; Ozeri, Dror; Veksler, Dekel; Kleiner, Vladimir; Hasman, Erez

    2013-05-10

    Spin optics provides a route to control light, whereby the photon helicity (spin angular momentum) degeneracy is removed due to a geometric gradient onto a metasurface. The alliance of spin optics and metamaterials offers the dispersion engineering of a structured matter in a polarization helicity-dependent manner. We show that polarization-controlled optical modes of metamaterials arise where the spatial inversion symmetry is violated. The emerged spin-split dispersion of spontaneous emission originates from the spin-orbit interaction of light, generating a selection rule based on symmetry restrictions in a spin-optical metamaterial. The inversion asymmetric metasurface is obtained via anisotropic optical antenna patterns. This type of metamaterial provides a route for spin-controlled nanophotonic applications based on the design of the metasurface symmetry properties.

  14. Spin-transfer torque induced spin waves in antiferromagnetic insulators

    Science.gov (United States)

    Daniels, Matthew; Guo, Wei; Stocks, G. Malcolm; Xiao, Di; Xiao, Jiang

    2015-03-01

    We explore the possibility of exciting spin waves in insulating antiferromagnetic films by injecting spin current at the surface. We analyze both magnetically compensated and uncompensated interfaces. We find that the spin current induced spin-transfer torque can excite spin waves in insulating antiferromagnetic materials and that the chirality of the excited spin wave is determined by the polarization of the injected spin current. Furthermore, the presence of magnetic surface anisotropy can greatly increase the accessibility of these excitations. Supported by NSF EFRI-1433496 (M.W.D), U.S. DOE Office of Basic Energy Sciences, Materials Sciences and Engineering (D.X. & G.M.S.), Major State Basic Research Project of China and National Natural Science Foundation of China (W.G. and J.X.).

  15. Spin anisotropy and slow dynamics in spin glasses.

    Science.gov (United States)

    Bert, F; Dupuis, V; Vincent, E; Hammann, J; Bouchaud, J-P

    2004-04-23

    We report on an extensive study of the influence of spin anisotropy on spin glass aging dynamics. New temperature cycle experiments allow us to compare quantitatively the memory effect in four Heisenberg spin glasses with various degrees of random anisotropy and one Ising spin glass. The sharpness of the memory effect appears to decrease continuously with the spin anisotropy. Besides, the spin glass coherence length is determined by magnetic field change experiments for the first time in the Ising sample. For three representative samples, from Heisenberg to Ising spin glasses, we can consistently account for both sets of experiments (temperature cycle and magnetic field change) using a single expression for the growth of the coherence length with time.

  16. Spin-Currents and Spin-Pumping Forces for Spintronics

    Directory of Open Access Journals (Sweden)

    Henri-Jean Drouhin

    2011-01-01

    Full Text Available A general definition of the Spintronics concept of spin-pumping is proposed as generalized forces conjugated to the spin degrees of freedom in the framework of the theory of mesoscopic non-equilibrium thermodynamics. It is shown that at least three different kinds of spin-pumping forces and associated spin-currents can be defined in the most simple spintronics system: the Ferromagnetic/Non-Ferromagnetic metal interface. Furthermore, the generalized force associated with the ferromagnetic collective variable is also introduced on an equal footing to describe the coexistence of the spin of the conduction electrons (paramagnetic spins attached to s-band electrons and the ferromagnetic-order parameter. The dynamical coupling between these two kinds of magnetic degrees of freedom is presented and interpreted in terms of spin-transfer effects.

  17. Numerical studies of Siberian snakes and spin rotators for RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luccio, A.

    1995-04-17

    For the program of polarized protons in RHIC, two Siberian snakes and four spin rotators per ring will be used. The Snakes will produce a complete spin flip. Spin Rotators, in pairs, will rotate the spin from the vertical direction to the horizontal plane at a given insertion, and back to the vertical after the insertion. Snakes, 180{degrees} apart and with their axis of spin precession at 90{degrees} to each other, are an effective means to avoid depolarization of the proton beam in traversing resonances. Classical snakes and rotators are made with magnetic solenoids or with a sequence of magnetic dipoles with fields alternately directed in the radial and vertical direction. Another possibility is to use helical magnets, essentially twisted dipoles, in which the field, transverse the axis of the magnet, continuously rotates as the particles proceed along it. After some comparative studies, the authors decided to adopt for RHIC an elegant solution with four helical magnets both for the snakes and the rotators proposed by Shatunov and Ptitsin. In order to simplify the construction of the magnets and to minimize cost, four identical super conducting helical modules will be used for each device. Snakes will be built with four right-handed helices. Spin rotators with two right-handed and two left-handed helices. The maximum field will be limited to 4 Tesla. While small bore helical undulators have been built for free electron lasers, large super conducting helical magnets have not been built yet. In spite of this difficulty, this choice is dictated by some distinctive advantages of helical over more conventional transverse snakes/rotators: (i) the devices are modular, they can be built with arrangements of identical modules, (ii) the maximum orbit excursion in the magnet is smaller, (iii) orbit excursion is independent from the separation between adjacent magnets, (iv) they allow an easier control of the spin rotation and the orientation of the spin precession axis.

  18. Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Mehmed, Oral; Johnson, Dexter; Montague, Gerald; Duffy, Kirsten; Jansen, Ralph

    2005-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig is an apparatus for vibration testing of turbomachine blades in a vacuum at rotational speeds from 0 to 40,000 rpm. This rig includes (1) a vertically oriented shaft on which is mounted an assembly comprising a rotor holding the blades to be tested, (2) two actively controlled heteropolar radial magnetic bearings at opposite ends of the shaft, and (3) an actively controlled magnetic thrust bearing at the upper end of the shaft. This rig is a more capable successor to a prior apparatus, denoted the Dynamic Spin Rig (DSR), that included a vertically oriented shaft with a mechanical thrust bearing at the upper end and a single actively controlled heteropolar radial magnetic bearing at the lower end.

  19. The Aharonov-Casher Effect for Particles of Arbitrary Spin

    CERN Document Server

    Azimov, Ya I

    1998-01-01

    The Aharonov-Casher (AC) effect for quantum motion of a neutral magnetized particle in the electric field is believed to be a topological effect closely related to the known Aharonov-Bohm (AB) effect. We study how it depends on the spin of the particle involved. Duality of the AB and AC effects is demonstrated to exist only for two extreme spin (and magnetic moment) projections. Classical consideration confirms the conclusion. Motion of a classical magnetized particle with generally oriented magnetic moment in the AC field appears to be subjected to both forces and torques. Only for two special orientations of the magnetic moment (same as in the quantum case) the motion is effectively free and similar to the AB motion of a charged particle. Thus, the AC effect is not really topological. Presence of higher multipoles totally destroys the possible AB-AC duality.

  20. Nonstochastic magnetic reversal in artificial quasicrystalline spin ice

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, B.; Bhat, V. S.; Woods, J.; Teipel, E.; Smith, N.; De Long, L. E., E-mail: delong@pa.uky.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States); Sklenar, J.; Ketterson, J. B. [Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 (United States); Hastings, J. T. [Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States)

    2014-05-07

    We have measured the isothermal DC magnetization of Penrose P2 tilings (P2T) composed of wire segments of permalloy thin film. Micromagnetic simulations reproduce the coercive fields and “knee anomalies” observed in experimental data and show magnetic shape anisotropy constrains segments to be single-domain (Ising spins) at low fields, similar to artificial spin ice (ASI). Mirror symmetry controls the initial reversal of individual segments oriented parallel to the applied field, followed by complex switching of multiple adjacent segments (“avalanches”) of various orientations such that closed magnetization loops (“vortices”) are favored. Ferromagnetic P2T differ from previously studied ASI systems due to their aperiodic translational symmetry and numerous inequivalent pattern vertices, which drive nonstochastic switching of segment polarizations.

  1. Nonstochastic magnetic reversal in artificial quasicrystalline spin ice

    Science.gov (United States)

    Farmer, B.; Bhat, V. S.; Sklenar, J.; Woods, J.; Teipel, E.; Smith, N.; Ketterson, J. B.; Hastings, J. T.; De Long, L. E.

    2014-05-01

    We have measured the isothermal DC magnetization of Penrose P2 tilings (P2T) composed of wire segments of permalloy thin film. Micromagnetic simulations reproduce the coercive fields and "knee anomalies" observed in experimental data and show magnetic shape anisotropy constrains segments to be single-domain (Ising spins) at low fields, similar to artificial spin ice (ASI). Mirror symmetry controls the initial reversal of individual segments oriented parallel to the applied field, followed by complex switching of multiple adjacent segments ("avalanches") of various orientations such that closed magnetization loops ("vortices") are favored. Ferromagnetic P2T differ from previously studied ASI systems due to their aperiodic translational symmetry and numerous inequivalent pattern vertices, which drive nonstochastic switching of segment polarizations.

  2. Spinning Dust Emission: Effects of irregular grain shape, transient heating and comparison with WMAP results

    CERN Document Server

    Hoang, Thiem; Draine, B T

    2011-01-01

    Planck is expected to answer crucial questions on the early Universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia $I_{1}\\ge I_{2}\\ge I_{3}$. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by $I_{1}:I_{2}:I_{3}$. We discuss how the orientation of dipole moment $\\bmu$ in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of $\\bmu$ than...

  3. Spin-disordered superfluid state for spin-1 bosons with fractional spin and statistics

    OpenAIRE

    2002-01-01

    We study a strongly correlated spin-1 Bose gas in 2D space by using the projective construction. A spin-disordered superfluid state is constructed and proposed as a candidate competing with the conventional polar condensate when interaction is antiferromagnetic. This novel state has a non-trivial topological order whose low energy excitations carry fractional spin, charge, and statistics. The spin excitations become gapless only at the edge and are described by level-1 SU(2) Kac-Moody algebra...

  4. Graphene as a reversible spin manipulator of molecular magnets.

    Science.gov (United States)

    Bhandary, Sumanta; Ghosh, Saurabh; Herper, Heike; Wende, Heiko; Eriksson, Olle; Sanyal, Biplab

    2011-12-16

    One of the primary objectives in molecular nanospintronics is to manipulate the spin states of organic molecules with a d-electron center, by suitable external means. In this Letter, we demonstrate by first principles density functional calculations, as well as second order perturbation theory, that a strain induced change of the spin state, from S=1→S=2, takes place for an iron porphyrin (FeP) molecule deposited at a divacancy site in a graphene lattice. The process is reversible in the sense that the application of tensile or compressive strains in the graphene lattice can stabilize FeP in different spin states, each with a unique saturation moment and easy axis orientation. The effect is brought about by a change in Fe-N bond length in FeP, which influences the molecular level diagram as well as the interaction between the C atoms of the graphene layer and the molecular orbitals of FeP.

  5. Electrical spin injection and detection of spin precession in room temperature bulk GaN lateral spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Aniruddha; Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: pkb@umich.edu [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2016-01-25

    We report the measurement of diffusive electronic spin transport characteristics in an epitaxial wurtzite GaN lateral spin valve at room temperature. Hanle spin precession and non-local spin accumulation measurements have been performed with the spin valves fabricated with FeCo/MgO spin contacts. Electron spin relaxation length and spin-flip lifetime of 176 nm and 37 ps, respectively, are derived from analysis of results obtained from four-terminal Hanle spin precession measurements at 300 K. The role of dislocations and defects in bulk GaN has also been examined in the context of electronic spin relaxation dynamics.

  6. Electrical spin injection and detection of spin precession in room temperature bulk GaN lateral spin valves

    Science.gov (United States)

    Bhattacharya, Aniruddha; Baten, Md Zunaid; Bhattacharya, Pallab

    2016-01-01

    We report the measurement of diffusive electronic spin transport characteristics in an epitaxial wurtzite GaN lateral spin valve at room temperature. Hanle spin precession and non-local spin accumulation measurements have been performed with the spin valves fabricated with FeCo/MgO spin contacts. Electron spin relaxation length and spin-flip lifetime of 176 nm and 37 ps, respectively, are derived from analysis of results obtained from four-terminal Hanle spin precession measurements at 300 K. The role of dislocations and defects in bulk GaN has also been examined in the context of electronic spin relaxation dynamics.

  7. Sexual Orientation (For Parents)

    Science.gov (United States)

    ... to reconcile their teen's sexual orientation with their religious or personal beliefs. Sadly, some react with anger, hostility, or rejection. But many parents find that they just need time to adjust ...

  8. Implementing Strategic Orientation

    Science.gov (United States)

    Fischer, Arthur K.; Brownback, Sarah

    2012-01-01

    An HRM case dealing with problems and issues of setting up orientation programs which align with corporate strategy. Discussion concerns how such a case can be used to exhibit the alignment between HRM and business strategy.

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

    NARCIS (Netherlands)

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

    2003-01-01

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

  10. Thermodynamic equivalence of spin systems

    Energy Technology Data Exchange (ETDEWEB)

    Beltman, J.M. (Katholieke Universiteit Nijmegen (Netherlands))

    1975-01-01

    The thermodynamic equilibrium properties of systems composed of classical spin /sup 1///sub 2/ particles (Ising spins) are studied. Given an interaction pattern between the Ising spins the main problem is to calculate the equilibrium state(s) of the system. The point put forward here is the existence of many thermodynamical equivalent spin coordinate systems. As a consequence of this phenomenon the interaction pattern of a system may be very intricate when described with respect to one spin coordinate system whereas it may become simple with respect to another one and vice versa. A systematic investigation of this phenomenon is made. (FR)

  11. Cultural Orientation and Interdisciplinarity

    DEFF Research Database (Denmark)

    Nielsen, Sofie Søndergaard

    2004-01-01

    I begin the article with an account of the background to the German debate on ‘Literaturwissenschaft als Kulturwissenschaft’, including the introduction of the concept of ’cultural orientation’ as a strategy for achieving interdisciplinarity. This is followed by a consideration of the discussion...... of the object of literary studies as a way of defining the disciplinarity or identity of literary studies. Finally I summarize some of the characteristics of culturally orientated literary studies....

  12. Anisotropic Paramagnetic Meissner Effect by Spin-Orbit Coupling

    Science.gov (United States)

    Espedal, Camilla; Yokoyama, Takehito; Linder, Jacob

    2016-03-01

    Conventional s -wave superconductors repel an external magnetic field. However, a recent experiment [A. Di Bernardo et al., Phys. Rev. X 5, 041021 (2015)] has tailored the electromagnetic response of superconducting correlations via adjacent magnetic materials. We consider another route of altering the Meissner effect where spin-orbit interactions induce an anisotropic Meissner response that changes sign depending on the field orientation. The tunable electromagnetic response opens new paths in the utilization of hybrid systems comprising magnets and superconductors.

  13. Exciton spin dynamics in ZnO epilayers

    Energy Technology Data Exchange (ETDEWEB)

    Lagarde, D.; Lombez, L.; Balocchi, A.; Renucci, P.; Carrere, H.; Amand, T.; Marie, X. [Laboratoire de Nanophysique, Magnetisme et Optoelectronique, INSA, 135 avenue de Rangueil, 31077 Toulouse Cedex 4 (France); Mei, Z.X.; Du, X.L.; Xue, Q.K. [Institute of Physics, Chinese Academy of Sciences and National Center for Nano-Science and Technology, Beijing 100080 (China)

    2007-07-01

    We used time-resolved optical orientation experiments to study the low temperature spin dynamics of a ZnO epilayer. The sample shows a circular polarisation of the donor-bound exciton of 11% with a decay time of 275 ps. A very narrow spectral dependence of the initial polarisation and a rapid decrease of the polarisation decay time with temperature are also observed. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Multinuclear solid state nuclear magnetic resonance investigation of water penetration in proton exchange membrane Nafion-117 by mechanical spinning.

    Science.gov (United States)

    Sabarinathan, Venkatachalam; Wu, Zhen; Cheng, Ren-Hao; Ding, Shangwu

    2013-05-30

    (1)H, (17)O, and (19)F solid state NMR spectroscopies have been used to investigate water penetration in Nafion-117 under mechanical spinning. It is found that both (1)H and (17)O spectra depend on the orientation of the membrane with respect to the magnetic field. The intensities of the side chain (19)F spectra depend slightly on the orientation of membrane with respect to the magnetic field, but the backbone (19)F spectra do not exhibit orientation dependence. By analyzing the orientation dependent (1)H and (17)O spectra and time-resolved (1)H spectra, we show that the water loaded in Nafion-117, under high spinning speed, may penetrate into regions that are normally inaccessible by water. Water penetration is enhanced as the spinning speed is increased or the spinning time is increased. In the meantime, mechanical spinning accelerates water exchange. It is also found that water penetration by mechanical spinning is persistent; i.e., after spinning, water remains in those newly found regions. While water penetration changes the pores and channels in Nafion, (19)F spectra indicate that the chemical environments of the polymer backbone do not show change. These results provide new insights about the structure and dynamics of Nafion-117 and related materials. They are relevant to proton exchange membrane aging and offer enlightening points of view on antiaging and modification of this material for better proton conductivity. It is also interesting to view this phenomenon in the perspective of forced nanofiltration.

  15. Investigation of the critical relaxation in MnF$_{2}$ by muon spin rotation

    CERN Document Server

    De Renzi, R; Cox, S F J; Guidi, G; Tedeschi, R A

    1982-01-01

    The magnetic relaxation in MnF/sub 2/ has been studied by means of Muon Spin Rotation. An increase was found close to T/sub N/ in the damping of the precession signal from positive muons implanted in a single-crystal sample. This is attributed to the critical slowing down of the antiferromagnetic spin fluctuations. An orientation-dependent shift in the signal frequency was also detected. The location of the muon in the lattice is tentatively determined.

  16. An exact solution on the ferromagnetic Face-Cubic spin model on a Bethe lattice

    OpenAIRE

    Ohanyan, V. R.; Ananikyan, L. N.; Ananikian, N. S.

    2006-01-01

    The lattice spin model with $Q$--component discrete spin variables restricted to have orientations orthogonal to the faces of $Q$-dimensional hypercube is considered on the Bethe lattice, the recursive graph which contains no cycles. The partition function of the model with dipole--dipole and quadrupole--quadrupole interaction for arbitrary planar graph is presented in terms of double graph expansions. The latter is calculated exactly in case of trees. The system of two recurrent relations wh...

  17. Dipolar field effects on the critical current for spin transfer switch of iron and permalloy nanoelements

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, L. L.; Dantas, J. T. S.; Souza, R. M.; Carriço, A. S., E-mail: ascarrico@gmail.com [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Dantas, Ana L. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, 59610-210 Mossoró, RN (Brazil)

    2014-05-07

    We report a theoretical study of dipolar effects on the switching current density of soft ferromagnetic elliptical nanoelements. Relevant changes on the critical current value are found according to the orientation of the magnetization and the spin polarization with the major axis. We show that the critical current density may be reduced by as much as 92% for thin nanoelements magnetized along the minor axis direction, using in-plane spin polarization parallel to the magnetization.

  18. Friction spinning - Twist phenomena and the capability of influencing them

    Science.gov (United States)

    Lossen, Benjamin; Homberg, Werner

    2016-10-01

    The friction spinning process can be allocated to the incremental forming techniques. The process consists of process elements from both metal spinning and friction welding. The selective combination of process elements from these two processes results in the integration of friction sub-processes in a spinning process. This implies self-induced heat generation with the possibility of manufacturing functionally graded parts from tube and sheets. Compared with conventional spinning processes, this in-process heat treatment permits the extension of existing forming limits and also the production of more complex geometries. Furthermore, the defined adjustment of part properties like strength, grain size/orientation and surface conditions can be achieved through the appropriate process parameter settings and consequently by setting a specific temperature profile in combination with the degree of deformation. The results presented from tube forming start with an investigation into the resulting twist phenomena in flange processing. In this way, the influence of the main parameters, such as rotation speed, feed rate, forming paths and tool friction surface, and their effects on temperature, forces and finally the twist behavior are analyzed. Following this, the significant correlations with the parameters and a new process strategy are set out in order to visualize the possibility of achieving a defined grain texture orientation.

  19. Quark spin-orbit correlations

    CERN Document Server

    Lorcé, Cédric

    2014-01-01

    The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.

  20. Efficient spin transport through polyaniline

    Science.gov (United States)

    Mendes, J. B. S.; Alves Santos, O.; Gomes, J. P.; Assis, H. S.; Felix, J. F.; Rodríguez-Suárez, R. L.; Rezende, S. M.; Azevedo, A.

    2017-01-01

    By using the spin pumping process, we show that it is possible to transport a pure spin current across layers of conducting polyaniline (PANI) with several hundred nanometers sandwiched between a film of the ferrimagnetic insulator yttrium iron garnet (YIG) and a thin layer of platinum. The spin current generated by microwave-driven ferromagnetic resonance of the YIG film, injected through the YIG/PANI interface, crosses the whole PANI layer and then is injected into the Pt layer. By means of the inverse spin Hall effect in the Pt, the spin current is converted into charge current and electrically detected as a dc voltage. We measured a spin diffusion length in PANI of 590 ± 40 nm, which is very large compared with normal metals, demonstrating that PANI can be used as an efficient spin current conductor and poor charge current conductor, opening the path towards spintronics applications based in this very attractive material.

  1. Spin Funneling for Enhanced Spin Injection into Ferromagnets

    Science.gov (United States)

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

    2016-07-01

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

  2. 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.

  3. Spins in Thin Films and Nanodevices

    Science.gov (United States)

    Tabor, Phillip

    The central theme of this work is the engineering of devices and materials that exhibit spin dependent phenomena. In particular, the spin orientation of charge carriers can play a central role in transport, especially in magnetic or other spin correlated media. Propagation of charge carriers with net spin results in a transfer of angular momentum that can excite static and dynamical states in active device elements. To utilize such phenomena in practical devices, new mew means of device characterization and optimization must be developed. To that end, we have performed experiments which elucidate some of the mechanisms underlying spin dependent transport phenomena. We report the observation of hysteretic synchronization of point contact spin torque nano-oscillators (STNOs) by a microwave magnetic field. The hysteresis was asymmetric with respect to the frequency detuning of the driving signal, and appeared in the region of a strong dependence of the oscillation frequency on the bias current. Theoretical analysis showed that hysteretic synchronization occurred when the width of the synchronization range, enhanced by the oscillator's nonlinearity, became comparable to the dissipation rate, while the observed asymmetry was a consequence of the nonlinear dependence of frequency on the bias current. Another emergent phenomenon was a series of fractional synchronization regimes in a STNO driven by a microwave field. These regimes are characterized by rational relations between the driving frequency and the frequency of the oscillation. Analysis based on the phase model of auto-oscillator indicates that fractional synchronization becomes possible when the driving signal breaks the symmetry of the oscillation, while the synchronization ranges are determined by the geometry of the oscillation orbit. Measurements of fractional synchronization were utilized to obtain information about the oscillation characteristics in nanoscale systems not accessible to direct imaging

  4. Spin Physics at COMPASS

    CERN Document Server

    Friedrich, Jan Michael

    2006-01-01

    Results for the spin structure of the nucleon from the COMPASS data taking periods 2002 to 2004 are presented. The quark contribution to the nucleon spin, following from a QCD fit to the new data, turns out to be significantly larger than it was derived from the previous world data. The new data favour, on the other side, a comparatively small gluon polarisation in the range $x_{g} \\approx$ 0.1. In the data taken with the deuteron target polarised transversely, the related asymmetries are found to be small on the level of accuracy reached so far, indicating a cancellation of the proton and neutron contributions. This is in agreement, for both the Collins and the Sivers asymmetry, with recent theoretical calculations. Also, a step towards the understanding of angular momentum contributions with COMPASS is taken by the evaluation of asymmetries in exclusive vector meson production.

  5. Large Spin Perturbation Theory

    CERN Document Server

    Alday, Luis F

    2016-01-01

    We consider conformal field theories around points of large twist degeneracy. Examples of this are theories with weakly broken higher spin symmetry and perturbations around generalised free fields. At the degenerate point we introduce twist conformal blocks. These are eigenfunctions of certain quartic operators and encode the contribution, to a given four-point correlator, of the whole tower of intermediate operators with a given twist. As we perturb around the degenerate point, the twist degeneracy is lifted. In many situations this breaking is controlled by inverse powers of the spin. In such cases the twist conformal blocks can be decomposed into a sequence of functions which we systematically construct. Decomposing the four-point correlator in this basis turns crossing symmetry into an algebraic problem. Our method can be applied to a wide spectrum of conformal field theories in any number of dimensions and at any order in the breaking parameter. As an example, we compute the spectrum of various theories ...

  6. Ground State Spin Logic

    CERN Document Server

    Whitfield, J D; Biamonte, J D

    2012-01-01

    Designing and optimizing cost functions and energy landscapes is a problem encountered in many fields of science and engineering. These landscapes and cost functions can be embedded and annealed in experimentally controllable spin Hamiltonians. Using an approach based on group theory and symmetries, we examine the embedding of Boolean logic gates into the ground state subspace of such spin systems. We describe parameterized families of diagonal Hamiltonians and symmetry operations which preserve the ground state subspace encoding the truth tables of Boolean formulas. The ground state embeddings of adder circuits are used to illustrate how gates are combined and simplified using symmetry. Our work is relevant for experimental demonstrations of ground state embeddings found in both classical optimization as well as adiabatic quantum optimization.

  7. Higher Spins in Hyperspace

    CERN Document Server

    Florakis, Ioannis; Tsulaia, Mirian

    2014-01-01

    We consider the Sp(2n) invariant formulation of higher spin fields on flat and curved backgrounds of constant curvature.In this formulation an infinite number of higher spin fields are packed into single scalar and spinor master fields (hyperfields) propagating on extended spaces, to be called hyperspaces, parametrized by tensorial coordinates.We show that the free field equations on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation of the scalar and spinor master fields. We compute the four--point functions on a flat hyperspace for both scalar and spinor master fields, thus extending the two-- and three--point function results of arXiv:hep-th/0312244. Then using the generalized conformal transformation we derive two--, three-- and four--point functions on AdS--like hyperspace from the corresponding correlators on the flat hyperspace.

  8. 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.

  9. Supersymmetric Spin Glass

    CERN Document Server

    Gukov, S G

    1997-01-01

    The evidently supersymmetric four-dimensional Wess-Zumino model with quenched disorder is considered at the one-loop level. The infrared fixed points of a beta-function form the moduli space $M = RP^2$ where two types of phases were found: with and without replica symmetry. While the former phase possesses only a trivial fixed point, this point become unstable in the latter phase which may be interpreted as a spin glass phase.

  10. Causal spin foams

    CERN Document Server

    Immirzi, Giorgio

    2016-01-01

    I discuss how to impose causality on spin-foam models, separating forward and backward propagation, turning a given triangulation to a 'causal set', and giving asymptotically the exponential of the Regge action, not a cosine. I show the equivalence of the prescriptions which have been proposed to achieve this. Essential to the argument is the closure condition for the 4-simplices, all made of space-like tetrahedra.

  11. Spinning yarns for years

    Science.gov (United States)

    Kowalewski, Grzegorz

    1997-05-01

    Applications of rather routine high speed photography techniques for research of some textile technologies invented, developed, improved or investigated by the Technical University of Lodz are presented. The following technologies and processes are mentioned: sewing, knitting, spinning, texturing, weaving (including pneumatic methods employed in some technologies). Rotating prism cameras, microsecond flash guns, stereo photography have been mainly applied. Most HSP applications and examples are illustrated by a video presentation.

  12. MU-SPIN Update

    Science.gov (United States)

    Harrington, James, Jr.

    2000-01-01

    Current goals are to: (1) Strengthen the science and engineering capabilities of MU-SPIN institutions in research and education via computer networks; (2) Involve and prepare minority institutions and principal investigators to successfully participate in competitive research and education processes via computer networks; and (3) Develop training and education mechanisms to support, sustain and evolve the institutional network infrastructure, thereby generating a better, prepared pool of candidates to contribute to NASA's missions.

  13. One-dimensional spinon spin currents

    Science.gov (United States)

    Hirobe, Daichi; Sato, Masahiro; Kawamata, Takayuki; Shiomi, Yuki; Uchida, Ken-Ichi; Iguchi, Ryo; Koike, Yoji; Maekawa, Sadamichi; Saitoh, Eiji

    2017-01-01

    Quantum spin fluctuation in a low-dimensional or frustrated magnet breaks magnetic ordering while keeping spin correlation. Such fluctuation has been a central topic in magnetism because of its relevance to high-Tc superconductivity and topological states. However, utilizing such spin states has been quite difficult. In a one-dimensional spin-1/2 chain, a particle-like excitation called a spinon is known to be responsible for spin fluctuation in a paramagnetic state. Spinons behave as a Tomonaga-Luttinger liquid at low energy, and the spin system is often called a quantum spin chain. Here we show that a quantum spin chain generates and carries spin current, which is attributed to spinon spin current. This is demonstrated by observing an anisotropic negative spin Seebeck effect along the spin chains in Sr2CuO3. The results show that spin current can flow even in an atomic channel owing to long-range spin fluctuation.

  14. Spin-dependent conductance of a typical fishbone-like nanostructure

    Directory of Open Access Journals (Sweden)

    M Mardaani

    2012-09-01

    Full Text Available In this study, we investigated the spin dependent electronic transport of a fishbone-like nanostructure including two magnetic atoms at its ends. The electronic conductance of this nanostructure for three different orientations of atomic magnetic moments was numerically studied when the structure was sandwiched between two nonmagnetic leads. By using Green’s function technique at the tight-binding model, we calculated the spin dependent electronic transmission coefficient. The calculated results revealed that the conductance depends on the incident electron energy as well as the magnitude and orientation of atomic magnetic moments in the nanostructure.

  15. Thermoelectrical manipulation of nano-magnets: a spin-thermionic oscillator

    Science.gov (United States)

    Kadigrobov, A. M.; Andersson, S.; Radić, D.; Shekhter, R. I.; Jonson, M.; Korenivski, V.

    2010-08-01

    We investigate the interplay between the thermodynamic properties and spin-dependent transport in a mesoscopic magnetic multilayer, in which two strongly ferromagnetic layers are exchange-coupled through a weakly ferromagnetic spacer. We show theoretically that the system allows a spin-thermoelectronic control of the relative orientation of the outer layers. Supporting experimental evidence of thermally controlled switching from parallel to anti-parallel magnetization orientations in the sandwich is presented. We show magneto-resistance oscillations may take place with frequencies up to GHz. We discuss in detail an experimental realization of a device that can operate as a thermo-magneto-resistive switch or oscillator.

  16. Nonergodic dynamics of nuclear spin 1/2 with equal constants of spin-spin interaction

    CERN Document Server

    Rudavets, M G

    2002-01-01

    The exact solution of the nuclear spins polarization evolution in the system with the similar q-constant spin-spin interaction (SSI) between all spin pairs is obtained in the case when only one (the first) spin was polarized at the initial time moment. It is shown that polarization of the first spin P sub 1 (t) has the form of periodical pulsations in the time with the 4 pi/g period. The P sub 1 (t) function changes in each period from the initial value P(0) = 1 up to 1/3 value during the time period of the t approx = 4 pi/Ng order, when the spins number is N >= 1 and remains in the P sub 1 (t) 1/3 state practically during the whole period. The simple classical model within the frames of the average field theory explains the physical cause of the nonergodic dynamics of the considered system

  17. Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect.

    Science.gov (United States)

    Chen, Wei; Sigrist, Manfred; Sinova, Jairo; Manske, Dirk

    2015-11-20

    In the normal-metal-ferromagnetic-insulator bilayer (such as Pt/Y_{3}Fe_{5}O_{12}) and the normal-metal-ferromagnetic-metal-oxide trilayer (such as Pt/Co/AlO_{x}) where spin injection and ejection are achieved by the spin Hall effect in the normal metal, we propose a minimal model based on quantum tunneling of spins to explain the spin-transfer torque and spin pumping caused by the spin Hall effect. The ratio of their dampinglike to fieldlike component depends on the tunneling wave function that is strongly influenced by generic material properties such as interface s-d coupling, insulating gap, and layer thickness, yet the spin relaxation plays a minor role. The quantified result renders our minimal model an inexpensive tool for searching for appropriate materials.

  18. Exchange interactions in transition metal oxides: the role of oxygen spin polarization

    Science.gov (United States)

    Logemann, R.; Rudenko, A. N.; Katsnelson, M. I.; Kirilyuk, A.

    2017-08-01

    Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides. To this end, we calculate the exchange interactions in NiO, MnO and hematite (Fe2O3) for different magnetic configurations using the magnetic force theorem. We consider the full spin Hamiltonian including oxygen sites, and also derive an effective model where the spin polarization on oxygen renormalizes the exchange interactions between TM sites. Surprisingly, the exchange interactions in NiO depend on the magnetic state if spin polarization on oxygen is neglected, resulting in non-Heisenberg behavior. In contrast, the inclusion of spin polarization in NiO makes the Heisenberg model more applicable. Just the opposite, MnO behaves as a Heisenberg magnet when oxygen spin polarization is neglected, but shows strong non-Heisenberg effects when spin polarization on oxygen is included. In hematite, both models result in non-Heisenberg behavior. The general applicability of the magnetic force theorem as well as the Heisenberg model to TM oxides is discussed.

  19. Optical Control of Coherent Interactions between Electron Spins in InGaAs Quantum Dots

    Science.gov (United States)

    2011-09-21

    A. Schwan,1 D. R. Yakovlev,1,3 D. Reuter,4 A. D. Wieck,4 T. L. Reinecke,2 and M. Bayer1 1Experimentelle Physik 2, Technische Universität Dortmund, D... trains orient spins normal to an external magnetic field, and particular subsets of spins precess in phase with the pulse trains . At rather low mag- netic...study here. In the present work, two subsets of spins are selected by spectrally narrow, circularly polarized laser pulse trains of different photon

  20. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    Energy Technology Data Exchange (ETDEWEB)

    Frougier, J., E-mail: julien.frougier@thalesgroup.com; Jaffrès, H.; Deranlot, C.; George, J.-M. [Unité Mixte de Physique CNRS-Thales and Université Paris Sud 11, 1 av. Fresnel, 91767 Palaiseau (France); Baili, G.; Dolfi, D. [Thales Research and Technology, 1 av. Fresnel, 91767 Palaiseau (France); Alouini, M. [Institut de Physique de Rennes, 263 Avenue Général Leclerc, 35042 Rennes (France); Sagnes, I. [Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis (France); Garnache, A. [Institut d' électronique du Sud CNRS UMR5214, Université Montpellier 2 Place Eugene Bataillon, 34095 Montpellier (France)

    2013-12-16

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.