Metal-insulator transition in Hubbard-like models with random hopping

TL;DR

This paper identifies a first-order metal-insulator transition in Hubbard-like models caused by the interplay of disorder and interactions, using a non-linear sigma model approach in higher dimensions.

Contribution

It reveals a disorder-interaction driven transition originating from chiral symmetry in Hubbard-like models with random hopping.

Findings

Instability indicative of a metal-insulator transition identified

Transition driven by disorder and interactions, not by nesting

Analysis performed using Finkel'stein Non-Linear Sigma Model

Abstract

An instability of a diffusive Fermi liquid, indicative of a metal-insulator transition (expected to be of first order), arising solely from the competition between quenched disorder and short-ranged interparticle interactions is identified in Hubbard-like models for spinless fermions, subject to (complex) random hopping at half-filling on bipartite lattices. The instability, found within a Finkel'stein Non-Linear Sigma Model treatment in d = (2 + epsilon) > 2 dimensions, originates from an underlying particle-hole like (so-called "chiral") symmetry, shared by both disorder and interactions. In the clean, interacting Fermi liquid this symmetry is responsible for the (completely different) "nesting" instability.