Search results for "RECESS"
showing 10 items of 379 documents
Role of spin diffusion in current-induced domain wall motion for disordered ferromagnets
2015
Current-induced spin transfer torque and magnetization dynamics in the presence of spin diffusion in disordered magnetic textures is studied theoretically. We demonstrate using tight-binding calculations that weak, spinconserving impurity scattering dramatically enhances the nonadiabaticity. To further explore this mechanism, a phenomenological drift-diffusion model for incoherent spin transport is investigated. We show that incoherent spin diffusion indeed produces an additional spatially dependent torque of the form ∼∇ 2 [m × (u · ∇)m] + ξ ∇ 2 [(u · ∇)m], where m is the local magnetization direction, u is the direction of injected current, and ξ is a parameter characterizing the spin dyna…
Ultrafast Spin Dynamics in Antiferromagnets
2018
Antiferromagnets are promising materials for spintronics because they show fast magnetic dynamics, low susceptibility to magnetic fields, and produce no stray fields. In addition, the antiferromagnetic dynamics can be efficiently manipulated by spin and charge currents. Here we discuss spin and/or charge current induced dynamics of the antiferromagnetic textures (domain walls, skyrmions) and nanoparticles. We consider and analyse four types of torques which (spin) current can generate in an antiferromagnet with two magnetic sublattices. These torques can be classified as the staggered/nonstaggered (S/ NS) according to the effective spin accumulation at the magnetic sublattices and the field…
Magnetic order and local field distribution in the hybrid magnets [FeCp*(2)][MnCr(ox)(3)] and [CoCp*(2)][FeFe(ox)(3)]: a muon spin relaxation study
2016
Zero-field muon spin relaxation (μ+SR) measurements on materials from the series [ZIIICp*2][M IIMIII(ox)3] show precession signals at several frequencies, characteristic of quasistatic magnetic fields at up to three distinct muon sites.
Limit on Lorentz andCPTviolation of the bound neutron using a free precessionHe3/Xe129comagnetometer
2010
We report on the search for Lorentz-violating sidereal variations of the frequency difference of colocated spin species while the Earth and hence the laboratory reference frame rotates with respect to a relic background field. The comagnetometer used is based on the detection of freely precessing nuclear spins from polarized 3 He and 129 Xe gas samples using SQUIDs as low-noise magnetic flux detectors. As result we can determine the limit for the equatorial component of the background field interacting with the spin of the bound neutron to be b n ⊥ < 3.7 · 10- 32 GeV (95% C.L.).
Spinrotator for MAMI
1991
A source of polarized electrons based on the photoemission of a GaAsP-cathode [1] has been set up to inject polarized electrons in the Mainz microtron MAMI. In order to compensate the spin precession in MAMI a spinrotator system has to be integrated in the 100 keV beamline from the source to the injector linac to achieve the required longitudinal spin direction at target position.
Positive Muons as Local Probes in Paramagnetic Rare Earth Systems
1982
In recent years a new research method has been developed in solid state physics which is based on the asymmetry of muon decay1. A positive muon at rest decays after a mean lifetime of 2.2 μsec into a positron and two neutrinos, the positron being emitted preferentially in the direction of the muon spin. Hence if spin polarized muons are implanted in a solid, the time evolution of the muon spin polarization can be determined by a measurement of the angular distribution of the positrons. In an external magnetic field transverse to the initial spin direction of the muon one can study the muon spin precession frequency, which is determined by the actual field at the muon, and τ2-relaxation effe…
Discovery of a Transition to Global Spin-up in EXO 2030+375
2005
EXO 2030+375, a 42-second transient X-ray pulsar with a Be star companion, has been observed to undergo an outburst at nearly every periastron passage for the last 13.5 years. From 1994 through 2002, the global trend in the pulsar spin frequency was spin-down. Using RXTE data from 2003 September, we have observed a transition to global spin-up in EXO 2030+375. Although the spin frequency observations are sparse, the relative spin-up between 2002 June and 2003 September observations, along with an overall brightening of the outbursts since mid 2002 observed with the RXTE ASM, accompanied by an increase in density of the Be disk, indicated by infrared magnitudes, suggest that the pattern obse…
Overdamped dynamics of paramagnetic ellipsoids in a precessing magnetic field
2009
We report on the dynamical behavior of paramagnetic ellipsoidal particles dispersed in water and floating above a flat plane when subjected to an external precessing magnetic field. When the magnetic field and the long axis of the particles are on the same plane, two clear regimes are distinguished in which the particles follow the magnetic modulation synchronously or asynchronously. Both regimes are also observed when the field precesses at an angle $\ensuremath{\vartheta}l90\ifmmode^\circ\else\textdegree\fi{}$ with respect to the normal to the confining plane, while the transition frequency increases with decreasing precession angle. We combine experimental observations with a theoretical…
Proposal for a Cosmic Axion Spin Precession Experiment (CASPEr)
2014
We propose an experiment to search for QCD axion and axionlike-particle dark matter. Nuclei that are interacting with the background axion dark matter acquire time-varying CP-odd nuclear moments such as an electric dipole moment. In analogy with nuclear magnetic resonance, these moments cause precession of nuclear spins in a material sample in the presence of an electric field. Precision magnetometry can be used to search for such precession. An initial phase of this experiment could cover many orders of magnitude in axionlike-particle parameter space beyond the current astrophysical and laboratory limits. And with established techniques, the proposed experimental scheme has sensitivity to …
A non-resonant dark-side solution to the solar neutrino problem
2001
We re-analyse spin-flavour precession solutions to the solar neutrino problem in the light of the recent SNO CC result as well as the 1258--day Super-Kamiokande data and the upper limit on solar anti-neutrinos. In a self-consistent magneto-hydrodynamics approach the resulting scheme has only 3 effective parameters: $\Delta m^2$, $\mu B_\perp$ and the neutrino mixing angle $\theta$. We show how a rates-only analysis for fixed $\mu B_\perp$ slightly favours spin-flavour precession (SFP) solutions over oscillations (OSC). In addition to the resonant solution (RSFP for short), there is a new non-resonant solution (NRSFP) in the ``dark-side''. Both RSFP and NRSFP lead to flat recoil energy spect…