Persistent Currents in Multichannel Interacting Systems

TL;DR

This paper investigates persistent currents in disordered multichannel mesoscopic rings with interacting spinless fermions, using exact and Hartree-Fock methods, revealing how interactions and chain coupling influence current distributions.

Contribution

It provides a comparative analysis of Hartree-Fock and exact results for persistent currents in multichannel systems, highlighting the role of interactions and disorder.

Findings

Repulsive interactions slightly decrease current distribution width.

Interactions increase the mean current in the diffusive regime.

Chain coupling is crucial for understanding large experimentally observed currents.

Abstract

Persistent currents of disordered multichannel mesoscopic rings of spinless interacting fermions threaded by a magnetic flux are calculated using exact diagonalizations and self-consistent Hartree-Fock methods. The validity of the Hartree-Fock approximation is controled by a direct comparison with the exact results on small $4\times4$ clusters. For sufficiently large disorder (diffusive regime), the effect of repulsive interactions on the current distribution is to slightly decrease its width (mean square current) but to {\it increase} its mean value (mean current). This effect is stronger in the case of a long range repulsion. Our results suggest that the coupling between the chains is essential to understand the large currents observed experimentally.