Circulating and persistent currents induced by a current magnification and Aharonov-Casher phase

TL;DR

This paper explores how circulating and persistent currents are induced by current magnification and Aharonov-Casher flux, highlighting their directional properties and conditions for their existence in quantum rings.

Contribution

It distinguishes between circulating and persistent currents, analyzing their dependence on flux, spin, and equilibrium conditions, and clarifies their behavior in quantum rings.

Findings

Persistent currents depend on Aharonov-Casher flux and are directional.

Circulating currents are independent of flux direction.

Persistent charge currents cancel due to time reversal symmetry, but spin currents persist.

Abstract

We considered the circulating current induced by the current magnification and the persistent current induced by Aharonov-Casher flux. The persistent currents have directional dependence on the direct current flow, but the circulating currents have no directional dependence. Hence in the equilibrium, only the persistent current can survives on the ring. For the charge current, the persistent charge current cancelled between spin up and down states, because of the time reversal symmetry of the Hamiltonian on the ring. So there are only circulating charge currents on the ring for electrons with unpolarized spin in the nonequilibrium. However, only the persistent spin currents contributes to the spin currents for electrons with unpolarized spin.