Interaction-tuned Anderson versus Mott localization

TL;DR

This paper investigates how disorder and strong interactions influence electron localization in a simple lattice model, revealing multiple insulating phases and clarifying the nature of metallic states.

Contribution

It demonstrates that the two-dimensional Falicov-Kimball model exhibits three distinct insulating phases and Anderson localization, clarifying the interplay between disorder and interactions.

Findings

Identification of three thermodynamic insulating phases

Presence of Anderson localization in the model

Metallic phase is a finite-size effect due to weak localization

Abstract

Disorder or sufficiently strong interactions can render a metallic state unstable causing it to turn into an insulating one. Despite the fact that the interplay of these two routes to a vanishing conductivity has been a central research topic, a unifying picture has not emerged so far. Here, we establish that the two-dimensional Falicov-Kimball model, one of the simplest lattice models of strong electron correlation does allow for the study of this interplay. In particular, we show that this model at particle-hole symmetry possesses three distinct thermodynamic insulating phases and exhibits Anderson localization. The previously reported metallic phase is identified as a finite-size feature due to the presence of weak localization. We characterize these phases by their electronic density of states, staggered occupation, conductivity, and the generalized inverse participation ratio. The implications of our findings for other strongly correlated systems are discussed.