Mott and Band Insulator Transitions in the Binary Alloy Hubbard Model

TL;DR

This study investigates how disorder and electron interactions in the binary alloy Hubbard model lead to Mott and band insulator transitions, revealing conditions for insulating and metallic phases through quantum Monte Carlo and exact diagonalization.

Contribution

It introduces a detailed analysis of insulating phases in the disordered Hubbard model using advanced numerical simulations, highlighting the role of local energy variance and percolation.

Findings

Mott insulating phases exist away from half filling with large local energy variance.

Metallic regions are only present if site energy density exceeds the percolation threshold.

Regions around the Mott phase can be Anderson insulators depending on disorder.

Abstract

We use determinant Quantum Monte Carlo simulations and exact diagonalization to explore insulating behavior in the Hubbard model with a bimodal distribution of randomly positioned local site energies. From the temperature dependence of the compressibility and conductivity, we show that gapped, incompressible Mott insulating phases exist away from half filling when the variance of the local site energies is sufficiently large. The compressible regions around this Mott phase are metallic only if the density of sites with the corresponding energy exceeds the percolation threshold, but are Anderson insulators otherwise.