Quantum Monte Carlo Study of an Interaction-Driven Band Insulator to Metal Transition

TL;DR

This paper uses determinant Quantum Monte Carlo to investigate the phase transitions in the ionic Hubbard model, revealing a finite metallic region and the role of antiferromagnetic order in the Mott insulator phase.

Contribution

It provides a detailed quantum Monte Carlo analysis of the interaction-driven transition from band insulator to metal and Mott insulator, highlighting the importance of intersite correlations.

Findings

Metallic region exists over a finite interaction range.

Mott phase exhibits antiferromagnetic order.

Intersite correlations alter the phase diagram significantly.

Abstract

We study the transitions from band insulator to metal to Mott insulator in the ionic Hubbard model on a two dimensional square lattice using determinant Quantum Monte Carlo. Evaluation of the temperature dependence of the conductivity demonstrates that the metallic region extends for a finite range of interaction values. The Mott phase at strong coupling is accompanied by antiferromagnetic (AF) order. Inclusion of these intersite correlations changes the phase diagram qualitatively compared to dynamical mean field theory.