Delocalization due to correlations in two-dimensional disordered systems

TL;DR

This paper investigates how interactions influence spectral properties in two-dimensional disordered fermionic systems, revealing that moderate Coulomb interactions can induce delocalization even under strong disorder conditions.

Contribution

It provides a full quantum numerical analysis of small systems showing interaction-induced delocalization and non-universal spectral features in 2D disordered lattices.

Findings

Weak disorder with interactions leads to localization.

Moderate Coulomb interactions cause delocalization at strong disorder.

Non-universal level-spacing distributions indicate reinforced spectral correlations.

Abstract

We study the spectral statistics of interacting spinless fermions in a two-dimensional disordered lattice. Within a full quantum treatment for small few-particle-systems, we compute the low-energy many-body states numerically. While at weak disorder the interactions reduce spectral correlations and lead to localization, for the case of strong disorder we find that a moderate Coulomb interaction has a delocalizing effect. In addition, we observe a non-universal structure in the level-spacing distribution which we attribute to a mechanism reinforcing spectral correlations taking place in small systems at strong disorder.