43 research outputs found
Drift-diffusion model for spin-polarized transport in a non-degenerate 2DEG controlled by a spin-orbit interaction
We apply the Wigner function formalism to derive drift-diffusion transport
equations for spin-polarized electrons in a III-V semiconductor single quantum
well. Electron spin dynamics is controlled by the linear in momentum spin-orbit
interaction. In a studied transport regime an electron momentum scattering rate
is appreciably faster than spin dynamics. A set of transport equations is
defined in terms of a particle density, spin density, and respective fluxes.
The developed model allows studying of coherent dynamics of a non-equilibrium
spin polarization. As an example, we consider a stationary transport regime for
a heterostructure grown along the (0, 0, 1) crystallographic direction. Due to
the interplay of the Rashba and Dresselhaus spin-orbit terms spin dynamics
strongly depends on a transport direction. The model is consistent with results
of pulse-probe measurement of spin coherence in strained semiconductor layers.
It can be useful for studying properties of spin-polarized transport and
modeling of spintronic devices operating in the diffusive transport regime.Comment: 16 pages, 3 figure
Dissipation effects in spin-Hall transport of electrons and holes
We investigate the spin-Hall effect of both electrons and holes in
semiconductors using the Kubo formula in the correct zero-frequency limit
taking into account the finite momentum relaxation time of carriers in real
semiconductors. This approach allows to analyze the range of validity of recent
theoretical findings. In particular, the spin-Hall conductivity vanishes for
vanishing spin-orbit coupling if the correct zero-frequency limit is performed.Comment: 5 pages, no figures, version to appear in Phys. Rev.
Anisotropic transport in the two-dimensional electron gas in the presence of spin-orbit coupling
In a two-dimensional electron gas as realized by a semiconductor quantum
well, the presence of spin-orbit coupling of both the Rashba and Dresselhaus
type leads to anisotropic dispersion relations and Fermi contours. We study the
effect of this anisotropy on the electrical conductivity in the presence of
fixed impurity scatterers. The conductivity also shows in general an anisotropy
which can be tuned by varying the Rashba coefficient. This effect provides a
method of detecting and investigating spin-orbit coupling by measuring
spin-unpolarized electrical currents in the diffusive regime. Our approach is
based on an exact solution of the two-dimensional Boltzmann equation and
provides also a natural framework for investigating other transport effects
including the anomalous Hall effect.Comment: 10 pages, 1 figure included. Discussion of experimental impact
enlarged; error in calculation of conductivity contribution corrected (cf.
Eq. (A14)), no changes in qualitative results and physical consequence