Spin-Hall transport of heavy holes in III-V semiconductor quantum wells

TL;DR

This paper analyzes the intrinsic spin-Hall effect of heavy holes in III-V semiconductor quantum wells with Rashba spin-orbit coupling, providing explicit formulas and exploring the impact of impurities on spin transport.

Contribution

It offers a closed-form expression for the spin-Hall conductivity of heavy holes, highlighting its enhancement over electrons and dependence on Rashba coupling and impurity scattering.

Findings

Spin-Hall conductivity is finite and depends on Rashba coupling and hole density.

Conductivity is enhanced compared to electron systems in the clean limit.

Impurity scattering reduces the spin-Hall conductivity.

Abstract

We investigate spin transport of heavy holes in III-V semiconductor quantum wells in the presence of spin-orbit coupling of the Rashba type due to structure-inversion asymmetry. Similarly to the case of electrons, the longitudinal spin conductivity vanishes, whereas the off-diagonal elements of the spin-conductivity tensor are finite giving rise to an intrinsic spin-Hall effect. For a clean system we find a closed expression for the spin-Hall conductivity depending on the length scale of the Rashba coupling and the hole density. In this limit the spin-Hall conductivity is enhanced compared to its value for electron systems, and it vanishes with increasing strength of the impurity scattering. As an aside, we also derive explicit expressions for the Fermi momenta and the densities of holes in the different dispersion branches as a function of the spin-orbit coupling parameter and the total hole density. These results are of relevance for the interpretation of possible Shubnikov-de Haas measurements detecting the Rashba spin splitting.