Enhancement of Persistent Currents by Hubbard Interactions In Disordered 1D Rings: Avoided Level Crossings Interpretation

TL;DR

This paper investigates how local electron interactions influence persistent currents in disordered 1D rings, revealing that onsite Hubbard interactions can enhance current, explained through avoided level crossings.

Contribution

It provides an analytic framework using avoided level crossings to explain the enhancement of persistent currents by Hubbard interactions in disordered rings.

Findings

Hubbard interactions enhance persistent currents in disordered rings.

Analytic formulas derived from avoided level crossings explain numerical results.

The approach also clarifies suppression effects in models with intersite interactions.

Abstract

We study effects of local electron interactions on the persistent current of one dimensional disordered rings. For different realizations of disorder we compute the current as a function of Aharonov-Bohm flux to zeroth and first orders in the Hubbard interaction. We find that the persistent current is {\em enhanced} by onsite interactions. Using an avoided level crossings approach, we derive analytic formulas which explain the numerical results at weak disorder. The same approach also explains the opposite effect (suppression) found for spinless fermion models with intersite interactions.