A local theory for Mott-Anderson localization

TL;DR

This paper investigates the breakdown of metallic behavior in the Anderson-Hubbard model near the metal-insulator transition, revealing a universal low-energy scale and crossover from Fermi liquid to incoherent dynamics.

Contribution

It introduces a non-perturbative local moment approach within dynamical mean field theory to identify a universal low energy scale and universal spectral dynamics near the transition.

Findings

Identification of a universal low energy scale $T_K^{peak}$

Observation of Fermi liquid to incoherent crossover in spectral dynamics

Spectral features governed by disorder-renormalized Kondo screening

Abstract

The paramagnetic metallic phase of the Anderson-Hubbard model (AHM) is investigated using a non-perturbative local moment approach within the framework of dynamical mean field theory with a typical medium. Our focus is on the breakdown of the metallic phase near the metal-insulators transition as seen in the single-particle spectra, scattering rates and the associated distribution of Kondo scales. We demonstrate the emergence of a universal, underlying low energy scale, $T_K^{peak}$. This lies close to the peak of the distribution of Kondo scales obtained within the metallic phase of the paramagnetic AHM. Spectral dynamics for energies, $\omega\lesssim T_K^{peak}$ display Fermi liquid universality crossing over to an incoherent universal dynamics for $\omega\gg T_K^{peak}$ in the scaling regime. Such universal dynamics indicate that within a local theory the low to moderately low energy physics is governed by an effective, {\it disorder renormalised} Kondo screening.