Collapse of Charge Gap in Random Mott Insulators

TL;DR

This paper investigates how randomness affects one-dimensional interacting fermionic systems, revealing a quantum phase transition where charge order collapses and the Mott gap closes, leading to localized low-energy states.

Contribution

It provides the first detailed quantum Monte Carlo analysis of the collapse of charge order and Mott gap in disordered one-dimensional fermionic models.

Findings

Randomness induces a quantum phase transition with charge order collapse.

The Mott gap closes due to disorder, creating low-energy states.

Localized low-lying states form without Fermi surface singularities.

Abstract

Effects of randomness on interacting fermionic systems in one dimension are investigated by quantum Monte-Carlo techniques. At first, interacting spinless fermions are studied whose ground state shows charge ordering. Quantum phase transition due to randomness is observed associated with the collapse of the charge ordering. We also treat random Hubbard model focusing on the Mott gap. Although the randomness closes the Mott gap and low-lying states are created, which is observed in the charge compressibility, no (quasi-) Fermi surface singularity is formed. It implies localized nature of the low-lying states.