16,157 research outputs found
D'yakonov-Perel' spin relaxation for degenerate electrons in the electron-hole liquid
We present an analytical study of the D'yakonov-Perel' spin relaxation time
for degenerate electrons in a photo-excited electron-hole liquid in intrinsic
semiconductors exhibiting a spin-split band structure. The D'yakonov-Perel'
spin relaxation of electrons in these materials is controlled by electron-hole
scattering, with small corrections from electron-electron scattering and
virtually none from electron-impurity scattering. We derive simple expressions
(one-dimensional and two-dimensional integrals respectively) for the effective
electron-hole and electron-electron scattering rates which enter the spin
relaxation time calculation. The electron-hole scattering rate is found to be
comparable to the scattering rates from impurities in the electron liquid - a
common model for n-type doped semiconductors. As the density of electron-hole
pairs decreases (within the degenerate regime), a strong enhancement of the
scattering rates and a corresponding slowing down of spin relaxation is
predicted due to exchange and correlation effects in the electron-hole liquid.
In the opposite limit of high density, the original D'yakonov-Perel' model
fails due to decreasing scattering rates and is eventually superseded by free
precession of individual quasiparticle spins.Comment: 16 pages, 5 figure
Hot-electron effect in spin dephasing in -type GaAs quantum wells
We perform a study of the effect of the high in-plane electric field on the
spin precession and spin dephasing due to the D'yakonov-Perel' mechanism in
-type GaAs (100) quantum wells by constructing and numerically solving the
kinetic Bloch equations. We self-consistently include all of the scattering
such as electron-phonon, electron-non-magnetic impurity as well as the
electron-electron Coulomb scattering in our theory and systematically
investigate how the spin precession and spin dephasing are affected by the high
electric field under various conditions. The hot-electron distribution
functions and the spin correlations are calculated rigorously in our theory. It
is found that the D'yakonov-Perel' term in the electric field provides a
non-vanishing effective magnetic field that alters the spin precession period.
Moreover, spin dephasing is markedly affected by the electric field. The
important contribution of the electron-electron scattering to the spin
dephasing is also discussed.Comment: 11 pages, 11 figures, accepted for publication in Phys. Rev.
Spin relaxation due to the Bir-Aronov-Pikus mechanism in intrinsic and -type GaAs quantum wells from a fully microscopic approach
We study the electron spin relaxation in intrinsic and -type (001) GaAs
quantum wells by constructing and numerically solving the kinetic spin Bloch
equations. All the relevant scatterings are explicitly included, especially the
spin-flip electron-heavy hole exchange scattering which leads to the
Bir-Aronov-Pikus spin relaxation. We show that, due to the neglection of the
nonlinear terms in the electron-heavy hole exchange scattering in the
Fermi-golden-rule approach, the spin relaxation due to the Bir-Aronov-Pikus
mechanism is greatly exaggerated at moderately high electron density and low
temperature in the literature. We compare the spin relaxation time due to the
Bir-Aronov-Pikus mechanism with that due to the D'yakonov-Perel' mechanism
which is also calculated from the kinetic spin Bloch equations with all the
scatterings, especially the spin-conserving electron-electron and
electron-heavy hole scatterings, included. We find that, in intrinsic quantum
wells, the effect from the Bir-Aronov-Pikus mechanism is much smaller than that
from the D'yakonov-Perel' mechanism at low temperature, and it is smaller by no
more than one order of magnitude at high temperature. In -type quantum
wells, the spin relaxation due to the Bir-Aronov-Pikus mechanism is also much
smaller than the one due to the D'yakonov-Perel' mechanism at low temperature
and becomes comparable to each other at higher temperature when the hole
density and the width of the quantum well are large enough. We claim that
unlike in the bulk samples, the Bir-Aronov-Pikus mechanism hardly dominates the
spin relaxation in two-dimensional samples.Comment: 10 pages, 6 figures, Phys. Rev. B 77, 2008, in pres
D'yakonov-Perel' spin relaxation in InSb/AlInSb quantum wells
We investigate theoretically the D'yakonov-Perel' spin relaxation time by
solving the eight-band Kane model and Poisson equation self-consistently. Our
results show distinct behavior with the single-band model due to the anomalous
spin-orbit interactions in narrow band-gap semiconductors, and agree well with
the experiment values reported in recent experiment (K. L. Litvinenko, et al.,
New J. Phys. \textbf{8}, 49 (2006)). We find a strong resonant enhancement of
the spin relaxation time appears for spin align along [] at a
certain electron density at 4 K. This resonant peak is smeared out with
increasing the temperature.Comment: 4 pages, 4 figure
Waveguide diffusion modes and slowdown of D'yakonov-Perel' spin relaxation in narrow 2-D semiconductor channels
We have shown that in narrow 2D semiconductor channels the D'yakonov-Perel'
spin relaxation rate is strongly reduced. This relaxation slowdown appears in
special waveguide diffusion modes which determine the propagation of spin
density in long channels. Experiments are suggested to detect the theoretically
predicted effects. A possible application is a field effect transistor operated
with injected spin current.Comment: 4 page
- âŠ