Correlation driven Mott-insulator-to-metal transition

TL;DR

This paper investigates how spatially varying interactions in a 2D Hubbard model induce two phase transitions, including an unconventional transition to an anisotropic metallic state driven by correlation effects.

Contribution

It introduces a study of correlation-driven phase transitions in a 2D Hubbard model with patterned interactions using quantum Monte Carlo simulations.

Findings

Identification of a transition from Mott insulator to anisotropic metal.

Observation of layer decoupling at large interactions.

Evidence of two distinct correlation-driven phase transitions.

Abstract

We study transport properties of the half-filled two-dimensional (2D) Hubbard model with spatially varying interactions, where a pattern of interacting and non-interacting sites is formed. We use Determinantal Quantum Monte Carlo method to calculate the double occupation, effective hopping and Drude weight. These data point to two phase transitions, driven by fermionic correlations. The first is the expected metal to a Mott insulating state. The second one, is an exotic transition from a Mott insulating state to a highly anisotropic metal, that takes place at large values of the fermion-fermion interaction. This second transition occurs when the layers formed by the spatially varying interactions decouple due to the suppression of the hopping between interacting and non-interacting sites, leading to fermionic transport along the non-interacting ones.