Spin-Hall effect and spin-coherent excitations in a strongly confined two-dimensional hole gas

TL;DR

This paper derives spin-charge coupled drift-diffusion equations for a strongly confined 2D hole gas, revealing the intrinsic spin-Hall effect, a threshold for spin transport regimes, and undamped spin-coherent oscillations.

Contribution

It introduces a rigorous quantum-kinetic framework to analyze spin-charge dynamics, identifying conditions for spin-Hall effect and coherent oscillations in confined hole gases.

Findings

Intrinsic spin-Hall effect observed at weak spin-orbit coupling.

Existence of a threshold separating diffusive and ballistic spin transport.

Detection of undamped spin-coherent oscillations in the ballistic regime.

Abstract

Based on a rigorous quantum-kinetic approach, spin-charge coupled drift-diffusion equations are derived for a strongly confined two-dimensional hole gas. An electric field leads to a coupling between the spin and charge degrees of freedom. For weak spin-orbit interaction, this coupling gives rise to the intrinsic spin-Hall effect. There exists a threshold value of the spin-orbit coupling constant that separates spin diffusion from ballistic spin transport. In the latter regime, undamped spin-coherent oscillations are observed. This result is confirmed by an exact microscopic approach valid in the ballistic regime.