Hydrodynamic model for spin-polarized electron transport in semiconductors

Abstract

We extend the hydrodynamic model of the Boltzmann equation by taking into account the spin of the nonequilibrium carriers injected into semiconducting systems. This spin-resolved hydrodynamic description goes beyond the usual drift-diffusion type approaches in a way that the temporal derivatives of the current densities are considered. This allows us to investigate the transient dynamics of spin-polarized packets in the diffusive and ballistic transport regimes. We have properly included the spin-polarized carriers from doping by solving our set of continuity equations and the Poisson equation self-consistently. We determine the spin-polarization landscapes (time and position) of the carrier density (n↑−n↓)∕(n↑+n↓) and the current density (j↑−j↓)∕(j↑+j↓). While in the uniformly doped system the carrier spin polarization has a slow decay, in the nonuniformly doped system it shows a drastic suppression in the interface. In contrast the current spin polarization exhibits an enhancement in this region. It can in principle be useful in designing submicron spintronic devices.