Do interactions increase or reduce the conductance of disordered electrons? It depends!

TL;DR

This paper examines how electron-electron interactions affect the conductance of disordered two-dimensional electrons, revealing that weak interactions can either increase or decrease conductance depending on the regime, while strong interactions always reduce it.

Contribution

It introduces an efficient numerical method to analyze low-energy properties of large disordered electron systems, clarifying the role of interactions in conductance behavior.

Findings

Weak interactions increase conductance in localized regime

Weak interactions decrease conductance in diffusive regime

Strong interactions decrease conductance regardless of regime

Abstract

We investigate the influence of electron-electron interactions on the conductance of two-dimensional disordered spinless electrons. By using an efficient numerical method which is based on exact diagonalization in a truncated basis of Hartree-Fock states we are able to determine the exact low-energy properties of comparatively large systems in the diffusive as well as in the localized regimes. We find that weak interactions increase the d.c. conductance in the localized regime while they decrease the d.c. conductance in the diffusive regime. Strong interactions always decrease the conductance. We also study the localization of single-particle excitations close to the Fermi energy which turns out to be only weakly influenced by the interactions.