108 research outputs found
Theory of laser-induced demagnetization at high temperatures
Laser-induced demagnetization is theoretically studied by explicitly taking
into account interactions among electrons, spins and lattice. Assuming that the
demagnetization processes take place during the thermalization of the
sub-systems, the temperature dynamics is given by the energy transfer between
the thermalized interacting baths. These energy transfers are accounted for
explicitly through electron-magnons and electron-phonons interaction, which
govern the demagnetization time scale. By properly treating the spin system in
a self-consistent random phase approximation, we derive magnetization dynamic
equations for a broad range of temperature. The dependence of demagnetization
on the temperature and pumping laser intensity is calculated in detail. In
particular, we show several salient features for understanding magnetization
dynamics near the Curie temperature. While the critical slowdown in dynamics
occurs, we find that an external magnetic field can restore the fast dynamics.
We discuss the implication of the fast dynamics in the application of heat
assisted magnetic recording.Comment: 11 Pages, 7 Figure
Spin Orientation of Holes in Quantum Wells
This paper reviews the spin orientation of spin-3/2 holes in quantum wells.
We discuss the Zeeman and Rashba spin splitting in hole systems that are
qualitatively different from their counterparts in electron systems. We show
how a systematic understanding of the unusual spin-dependent phenomena in hole
systems can be gained using a multipole expansion of the spin density matrix.
As an example we discuss spin precession in hole systems that can give rise to
an alternating spin polarization. Finally, we discuss the qualitatively
different regimes of hole spin polarization decay in clean and dirty samples.Comment: 14 pages, 8 figure
Non-Markovian spin relaxation in two-dimensional electron gas
We analyze by Monte-Carlo simulations and analytically spin dynamics of
two-dimensional electron gas (2DEG) interacting with short-range scatterers in
nonquantizing magnetic fields. It is shown that the spin dynamics is
non-Markovian with the exponential spin relaxation followed by the oscillating
tail due to the electrons residing on the closed trajectories. The tail relaxes
on a long time scale due to an additional smooth random potential and inelastic
processes. The developed analytical theory and Monte-Carlo simulations are in
the quantitative agreement with each other.Comment: 6 pages, 3 figure
Laser in the axial electric field as a tool to search for P-, T- invariance violation
We consider rotation of polarization plane of the laser light when a gas
laser is placed in a longitudinal electric field (10~kV/cm). It is shown that
residual anisotropy of the laser cavity 10^{-6} and the sensitivity to the
angle of polarization plane rotation about 10^{-11} -10^{-12} rad allows one to
measure an electron EDM with the sensitivity about 10^{-30} e cm.Comment: 12 page
Magneto-gyrotropic effects in semiconductor quantum wells (review)
Magneto-gyrotropic photogalvanic effects in quantum wells are reviewed. We
discuss experimental data, results of phenomenological analysis and microscopic
models of these effects. The current flow is driven by spin-dependent
scattering in low-dimensional structures gyrotropic media resulted in asymmetry
of photoexcitation and relaxation processes. Several applications of the
effects are also considered.Comment: 28 pages, 13 figure
QCD Heat Kernel in Covariant Gauge
We report the calculation of the fourth coefficient in an expansion of the
heat kernel of a non-minimal, non-abelian kinetic operator in an arbitrary
background gauge in arbitrary space-time dimension. The fourth coefficient is
shown to bring a nontrivial gauge dependence due to the contribution of the
lowest order off-shell gauge invariant structure.Comment: 6 pages + title page, standart LaTe
QCD partition function in the external field in the covariant gauge
The QCD partition function in the external stationary gluomagnetic field is
computed in the third order in external field invariants in arbitrary dimension
and arbitrary covariant gauge. The contributions proportional to third order
invariants in gluon field strength are shown to be dependent on covariant
quantum gauge fixing parameter \alph
Spin relaxation in low-dimensional systems
We review some of the newest findings on the spin dynamics of carriers and
excitons in GaAs/GaAlAs quantum wells. In intrinsic wells, where the optical
properties are dominated by excitonic effects, we show that exciton-exciton
interaction produces a breaking of the spin degeneracy in two-dimensional
semiconductors. In doped wells, the two spin components of an optically created
two-dimensional electron gas are well described by Fermi-Dirac distributions
with a common temperature but different chemical potentials. The rate of the
spin depolarization of the electron gas is found to be independent of the mean
electron kinetic energy but accelerated by thermal spreading of the carriers.Comment: 1 PDF file, 13 eps figures, Proceedings of the 1998 International
Workshop on Nanophysics and Electronics (NPE-98)- Lecce (Italy
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