Spin accumulation in ballistic Rashba bar

TL;DR

This paper presents an analytical model demonstrating that a ballistic Rashba bar can exhibit out-of-plane spin Hall accumulation due to unpolarized current injection, with effects influenced by the Rashba coupling strength and sample size.

Contribution

It introduces an analytic approach to study spin accumulation in ballistic Rashba systems, highlighting size effects and the impact of Rashba coupling on spin polarization.

Findings

Out-of-plane spin Hall accumulation occurs in large Rashba bars with unpolarized current.

In-plane spin Hall effect diminishes in large samples.

Adjusting Rashba coupling can flip the out-of-plane spin accumulation.

Abstract

We propose an analytic model to study intrinsic spin polarization effect in a ballistic Rashba bar with two semi-infinite leads. The wave functions expanded with plane waves in Rashba bar are required to satisfy boundary conditions at both longitudinal and transverse interfaces. We find out-of-plane spin Hall accumulation effect can be induced in the Rashba bar even with large dimensions by injecting unpolarized current from the lead. The longitudinal in-plane spin Hall effect, however, becomes obscure in large-size sample. An interesting direction-flipping of the out-of-plane spin accumulation is predicted by altering the Rashba coupling strength.