Spin Hall Current Driven by Quantum Interferences in Mesoscopic Rashba Rings

TL;DR

This paper predicts a purely electrical method to generate and control spin currents in a quantum ring using Rashba spin-orbit coupling, exploiting quantum interference effects for potential spintronic applications.

Contribution

It introduces a novel mesoscopic Rashba ring setup that produces a pure spin current via quantum interference, highlighting the role of Aharonov-Casher phases.

Findings

Spin Hall current oscillates with Rashba coupling.

Amplitude of spin current is comparable to 2D electron gases.

Disorder and width reduce the spin Hall effect.

Abstract

We propose an all-electrical nanoscopic structure where {\em pure} spin current is induced in the transverse voltage probes attached to {\em quantum-coherent} one-dimensional ring when conventional unpolarized charge current is injected through its longitudinal leads. Tuning of the Rashba spin-orbit coupling in semiconductor heterostructure hosting the ring generates quasi-periodic oscillations of the predicted spin Hall current due to {\em spin-sensitive quantum-interference effects} caused by the difference in Aharonov-Casher phase acquired by opposite spins states traveling clockwise and counterclockwise. Its amplitude is comparable to the mesoscopic spin Hall current predicted for finite-size two-dimensional electron gases, while it gets reduced in wide two-dimensional or disordered rings.