Persistent spin and charge currents and magnification effects in open ring conductors subject to Rashba coupling

TL;DR

This paper investigates how Rashba spin-orbit coupling and a tunnel barrier influence persistent spin and charge currents in a mesoscopic ring, revealing spin current magnification and pure spin current generation for spintronics.

Contribution

It demonstrates the generation and magnification of persistent spin currents in a ring with Rashba coupling, highlighting new control mechanisms for spintronics devices.

Findings

Persistent spin current can be induced independently of charge current.

Magnification of spin current occurs near Fano antiresonances.

Pure spin current can be produced at transmittance zeros.

Abstract

We analyze the effect of Rashba spin-orbit coupling and of a local tunnel barrier on the persistent spin and charge currents in a one-dimensional conducting Aharonov-Bohm (AB) ring symmetrically coupled to two leads. First, as an important consequence of the spin-splitting, it is found that a persistent spin current can be induced which is not simply proportional to the charge current. Second, a magnification effect of the persistent spin current is shown when one tunes the Fermi energy near the Fano-type antiresonances of the total transmission coefficient governed by the tunnel barrier strength. As an unambiguous signature of spin-orbit coupling we also show the possibility to produce a persistent pure spin current at the interference zeros of the transmittance. This widens the possibilities of employing mesoscopic conducting rings in phase-coherent spintronics applications.