Persistent current in ballistic mesoscopic rings with Rashba spin-orbit coupling

TL;DR

This paper investigates how Rashba spin-orbit coupling influences persistent charge and spin currents in mesoscopic rings, providing methods to detect and measure the spin splitting through flux-dependent current behaviors.

Contribution

It introduces a way to identify and quantify Rashba spin splitting in mesoscopic rings by analyzing flux-induced sign changes in persistent charge currents and highlights the existence of a persistent spin current.

Findings

Sign changes in persistent charge current reveal spin splitting strength.

Persistent spin current exists independently of charge current.

Flux dependence of currents uniquely indicates spin-orbit effects.

Abstract

The presence of spin-orbit coupling affects the spontaneously flowing persistent currents in mesoscopic conducting rings. Here we analyze their dependence on magnetic flux with emphasis on identifying possibilities to prove the presence and extract the strength of Rashba spin splitting in low-dimensional systems. Effects of disorder and mixing between quasi-onedimensional ring subbands are considered. The spin-orbit coupling strength can be inferred from the values of flux where sign changes occur in the persistent charge current. As an important consequence of the presence of spin splitting, we identify a nontrivial persistent spin current that is not simply proportional to the charge current. The different flux dependences of persistent charge and spin currents are a unique signature of spin-orbit coupling affecting the electronic structure of the ring.