Quantum critical transport at a continuous metal-insulator transition

TL;DR

This paper investigates quantum critical transport at a continuous metal-insulator transition using the Falicov-Kimball model, revealing anomalous scaling behavior and potential relevance to real disordered systems.

Contribution

It demonstrates quantum critical scaling and a log(g) beta-function in a disordered model, providing insights into strong localization phenomena.

Findings

Mirror symmetry of scaling curves across the transition

Beta-function scales as log(g) deep in the bad-metallic phase

Quantum criticality may occur in real disordered 3D systems

Abstract

In contrast to the first-order correlation-driven Mott metal-insulator transition (MIT), contin- uous disorder-driven transitions are intrinsically quantum critical. Here, we investigate transport quantum criticality in the Falicov-Kimball model, a representative of the latter class in the "strong disorder" category. Employing cluster-dynamical mean-field theory (CDMFT), we find clear and anomalous quantum critical scaling behavior manifesting as perfect mirror symmetry of scaling curves on both sides of the MIT. Surprisingly, we find that the beta-function, \b{eta}(g), scales like log(g) deep into the bad-metallic phase as well, providing sound unified basis for these findings. We argue that such "strong localization" quantum criticality may manifest in real three-dimensional systems where disorder effects are more important than electron-electron interactions.