Can Non-Equilibrium Spin Hall Accumulation be Induced in Ballistic Nanostructures?

TL;DR

This paper predicts that unpolarized current in ballistic 2D electron gases with Rashba coupling induces measurable spin accumulation at edges, with characteristics that help distinguish underlying spin Hall mechanisms.

Contribution

It introduces the concept of non-equilibrium spin Hall accumulation in ballistic nanostructures and proposes experimental signatures to differentiate spin Hall effects.

Findings

Edge spin accumulation has opposite signs for lateral edges.

Disorder diminishes out-of-plane spin accumulation.

Transverse magnetic field enhances spin accumulation.

Abstract

We demonstrate that flow of longitudinal unpolarized current through a ballistic two-dimensional electron gas with Rashba spin-orbit coupling will induce nonequilibrium spin accumulation which has opposite sign for the two lateral edges and it is, therefore, the principal observable signature of the spin Hall effect in two-probe semiconductor nanostructures. The magnitude of its out-of-plane component is gradually diminished by static disorder, while it can be enhanced by an in-plane transverse magnetic field. Moreover, our prediction of the longitudinal component of the spin Hall accumulation, which is insensitive to the reversal of the bias voltage, offers a smoking gun to differentiate experimentally between the extrinsic, intrinsic, and mesoscopic spin Hall mechanisms.