Influence of spin on the persistent current of strongly interacting electrons

TL;DR

This paper investigates how electron spin and strong interactions affect persistent currents in a one-dimensional ring with impurities, revealing oscillations, enhancement, and temperature-dependent behavior.

Contribution

It provides new insights into the influence of spin and strong electron-electron interactions on persistent currents in mesoscopic rings.

Findings

Spin causes oscillations in ground state flux response.

Strong interactions enhance persistent current but do not reach free electron levels.

Persistent current vanishes exponentially with temperature depending on electron density.

Abstract

The lowest eigenenergies of few, strongly interacting electrons in a one--dimensional ring are studied in the presence of an impurity barrier. The persistent current $\:I\:$, periodic in an Aharonov--Bohm flux penetrating the ring, is strongly influenced by the electron spin. The impurity does not remove discontinuities in $\:I\:$ at zero temperature. The total electron spin of the ground state oscillates with the flux. Strong electron--electron interaction enhances $\:I\:$, albeit not up to the value of the clean ring which itself is smaller than $\:I\:$ for free electrons. $\:I\:$ disappears on a temperature scale that depends exponentially on the electron density. In the limit of very strong interaction the response to small fluxes is diamagnetic.