Drift-diffusion model for spin-polarized transport in a non-degenerate 2DEG controlled by a spin-orbit interaction

TL;DR

This paper develops a drift-diffusion model for spin-polarized electron transport in a non-degenerate 2D electron gas, incorporating spin-orbit interactions, and analyzes how spin dynamics depend on transport direction and material parameters.

Contribution

The paper introduces a novel drift-diffusion formalism based on the Wigner function for spin-polarized transport in quantum wells with spin-orbit coupling, enabling analysis of coherent spin dynamics.

Findings

Spin dynamics depend on transport direction due to Rashba and Dresselhaus interactions.

The model aligns with pulse-probe measurements of spin coherence.

It provides a framework for modeling spintronic devices in diffusive regimes.

Abstract

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.