Persistent currents in ballistic normal-metal rings

TL;DR

This paper investigates how Zeeman splitting affects persistent currents in ballistic normal-metal rings under high magnetic fields and discusses thermal fluctuations indicating electron coherence at elevated temperatures.

Contribution

It introduces the effect of Zeeman splitting on persistent current quenching and explores thermal fluctuations as evidence of electron coherence at high temperatures.

Findings

Zeeman splitting causes periodic current quenching in ballistic rings.

Thermal fluctuations of persistent current can indicate high-temperature electron coherence.

Effect may also be relevant for diffusive rings.

Abstract

Recent experiments renewed interest in persistent currents in mesoscopic normal-metal rings. We show that in ballistic rings in high magnetic fields the Zeeman splitting leads to periodic current quenching with period much larger than the period of the persistent current. Simple arguments show that this effect might be relevant for diffusive rings as well. Another aim of this paper is to discuss fluctuations of the persistent current due to thermal excitation of high energy levels. Being observed such fluctuations would witness a coherent state of an electron system at high temperatures when the persistent current is exponentially suppressed.