Spin-Hall and spin-diagonal conductivity in the presence of Rashba and Dresselhaus spin-orbit coupling

TL;DR

This paper analyzes the spin-current response in a 2D electron gas with Rashba and Dresselhaus spin-orbit coupling, revealing how the spin-Hall conductivity depends on their relative strengths and identifying a new spin current generation effect.

Contribution

It introduces a novel effect where a spin current aligns with the electric field direction when Dresselhaus coupling is present, and clarifies the dependence of spin-Hall conductivity on coupling strengths.

Findings

Spin-Hall conductivity depends on the sign of the difference between Rashba and Dresselhaus strengths.

A new spin current is generated in the direction of the electric field when Dresselhaus coupling is nonzero.

The effect's experimental detection is feasible with current sample parameters.

Abstract

We investigate the spin-current linear response conductivity tensor to an electric field in a paramagnetic two dimensonal electron gas with both Rashba and Dresselhaus spin-orbit coupling in the weak scattering regime. In the ususal case where both spin-orbit-split bands are occupied, we find that the spin-Hall conductivity depends only on the sign of the difference in magnitude of the Rashba and Dresselhaus coupling strengths except within a narrow window where both coupling strengths are equal. We also find a new effect in which a spin current is generated in the direction of the driving field whenever the Dresselhaus spin-orbit coupling is nonzero. We discuss experimental implications of this finding taking into account the finite mobility and typical parameters of current samples and possible experimental set ups for its detection.