Persistant Current in Isolated Mesoscopic Rings

TL;DR

This paper investigates persistent currents in isolated mesoscopic rings, analyzing effects of disorder, temperature, and electron spin, and confirms known parity effects with new generalizations.

Contribution

It extends previous studies by including electron spin, disorder, and finite temperature effects, providing a generalized understanding of parity effects in persistent currents.

Findings

Disorder converts flux periodicity from half to full quantum.

Finite temperature reduces current magnitude but preserves flux periodicity.

Sign of persistent current can change with disorder and temperature.

Abstract

Persistant current in isolated mesoscopic rings is studied using the continium and tight-binding models of independent electrons. The calculation is performed with disorder and also at finite temperature. In the absence of disorder and at zero temperature agreement is obtained with earlier results by D. Loss et. al., in that there is half quantum flux periodicity for a large and odd number of electrons, but full quantum periodicity for any even number of electrons in the ring. Strong, disorder converts the period into full quantum periodicity. Finite temperature reduces the magnitude of the current, but preserves the quantum flux periodicity at zero temperature. However the sign of the current may change as disorder or temperature is increased. A generalization of the parity effect, previously discussed by Legett, Loss and Kusmartsev is described for the case where there are electrons with spin, influenced by finite temperature and disorder.