Delocalized Coulomb phase in two dimensions

TL;DR

This paper proposes that Coulomb interactions can induce a delocalized, metallic phase in two-dimensional disordered systems of spinless fermions, challenging the traditional view of localization in 2D.

Contribution

It extends finite size scaling theory to many-body ground states, revealing a Coulomb-driven transition from insulator to extended phase in 2D systems.

Findings

Transition at Coulomb to Fermi energy ratio r_s ≈ 4

Change in persistent current behavior at transition

Relevance to observed 2D metallic phase

Abstract

Extending finite size scaling theory to the many body ground state, one finds that Coulomb repulsion can drive a system of spinless fermions in a random potential from the Anderson insulator (Fermi glass of localized states) towards a new extended phase in dimension $d=2$. The transition occurs at a Coulomb energy to Fermi energy ratio $r_s \approx 4$, where a change in the nature of the persistent currents has been previously observed. Relevance to the recently observed $2d$ metallic phase is suggested.