Anderson localization effects near the Mott metal-insulator transition

TL;DR

This paper investigates how disorder and electron interactions jointly influence the metal-insulator transition, revealing that strong disorder suppresses the coexistence region and leads to a direct transition without phase coexistence.

Contribution

It combines dynamical mean field theory with typical medium theory to analyze the Mott-Anderson transition at finite temperatures, highlighting the impact of disorder strength on phase coexistence.

Findings

Weak disorder preserves the coexistence region similar to the clean case.

Strong disorder shrinks the coexistence region and suppresses the critical temperature.

At high disorder, a direct transition occurs without phase coexistence.

Abstract

The interplay between Mott and Anderson routes to localization in disordered interacting systems gives rise to different transitions and transport regimes. Here, we investigate the phase diagram at finite temperatures using dynamical mean field theory combined with typical medium theory, which is an effective theory of the Mott-Anderson metal-insulator transition. We mainly focus on the properties of the coexistence region associated with the Mott phase transition. For weak disorder, the coexistence region is found to be similar as in the clean case. However, as we increase disorder Anderson localization effects are responsible for shrinking the coexistence region and at sufficiently strong disorder (approximately equal to twice the bare bandwidth) it drastically narrows, the critical temperature abruptly goes to zero, and we observe a phase transition in the absence of a coexistence of the metallic and insulating phases. In this regime, the effects of interaction and disorder are found to be of comparable importance for charge localization.