Semiconductor Analog of the Large Persistent Currents Observed in Small Gold Rings

TL;DR

This paper predicts that ballistic semiconductor rings with potential barriers can exhibit large persistent currents similar to those observed in gold rings, highlighting fundamental differences in non-equilibrium and equilibrium transport phenomena.

Contribution

It introduces a theoretical prediction that semiconductor rings can host large persistent currents despite low transmission, extending understanding of persistent currents beyond metallic systems.

Findings

Semiconductor rings can exhibit large persistent currents (~ evF/L).

Persistent currents occur even with low electron transmission probability.

The phenomenon is linked to fundamental differences in transport phenomena.

Abstract

The remarkably large persistent currents that are observed in disordered micron-scale gold rings at low temperatures have recently been explained in a theory of non-interacting electrons scattered by crystal grain boundaries. The present article examines the possibility that the basic physics underlying this explanation may also have observable consequences in a different system, a ballistic two-dimensional semiconductor ring with a potential barrier. It is predicted, using computer simulations, that such semiconductor rings can exhibit large persistent currents ~ evF/L (L is the ring circumference), despite the electron transmission probability through the barrier being small, in the regime of quantum-mechanical tunneling of electrons through the barrier. This, like the phenomenon observed in gold rings, is a manifestation of the fundamental dissimilarity of non-equilibrium transport phenomena and equilibrium persistent currents.