Inhomogeneous metallic phase upon disordering a two dimensional Mott insulator

TL;DR

This study reveals that in a 2D Mott insulator, disorder can locally destroy the spectral gap, creating an inhomogeneous metallic phase with coexisting antiferromagnetic order, challenging traditional understanding of insulating states.

Contribution

The paper demonstrates that disorder induces a novel inhomogeneous metallic phase in a 2D Mott insulator, highlighting the role of local gap destruction and puddle formation.

Findings

Disorder destroys the spectral gap in the Mott insulator.

Inhomogeneous metallic regions coexist with antiferromagnetic order.

Increasing disorder leads to extended states and metallic behavior.

Abstract

We find that isoelectronic disorder destroys the spectral gap in a Mott-Hubbard insulator in 2D leading, most unexpectedly, to a new metallic phase. This phase is spatially inhomogeneous with metallic behavior coexisting with antiferromagnetic long range order. Even though the Mott gap in the pure system is much larger than antiferromagnetic exchange, the spectral gap is destroyed locally in regions where the disorder potential is high enough to overcome the inter-electron repulsion thereby generating puddles where charge fluctuations are enhanced. With increasing disorder, these puddles expand and concomitantly the states at the Fermi energy get extended leading to a metallic phase. We discuss the implications of our results for experiments.