Role of relaxation in spin Hall effect

TL;DR

This paper investigates how relaxation processes affect the spin Hall effect in 2D models, finding that the intrinsic spin Hall effect remains robust against disorder and that p-type models show significantly larger spin accumulation.

Contribution

It provides a quantitative analysis of relaxation effects on the intrinsic spin Hall effect in Rashba and Luttinger models, highlighting robustness and differences between n-type and p-type systems.

Findings

Intrinsic SHE is robust against realistic disorder levels.

Spin accumulation is significantly larger in p-type models.

Experimental observations are supported by the model results.

Abstract

The role of the relaxation due to the impurity scattering and/or the contacts to leads/electrodes are studied for the spin Hall effect (SHE). Relaxation is essential to attain the steady state and also to the spin accumulation, but has been considered to be harmful for the intrinsic SHE (ISHE). These issues are examined quantitatively on two types of 2D models, i.e., (a) Rashba model for $n$-type GaAs, and (b) Luttinger model for $p$-type GaAs. It is found that ISHE is robust against the realistic strength of the disorder producing the observable amount of the spin accumulation. Especially in model (b) the spin current and the accumulation are an order of magnitude larger than those in model (a). Experimental observations are discussed quantitatively from these results.