Quantum critical local spin dynamics near the Mott metal-insulator transition in infinite dimensions

TL;DR

This paper investigates the local spin dynamics near the Mott transition in a Hubbard model using Dynamical Mean-Field Theory, revealing quantum critical behavior characterized by /T scaling in a specific phase region.

Contribution

It provides the first detailed calculation of local dynamical spin susceptibility across different phases near the Mott transition in infinite dimensions.

Findings

Identification of /T scaling in the quantum critical region

Distinct dynamical behaviors in insulator, metal, and bad metal phases

Consistency with experimental observations on organic charge transfer salts

Abstract

Finding microscopic models for metallic states that exhibit quantum critical properties such as $\omega/T$ scaling is a major theoretical challenge. We calculate the local dynamical spin susceptibility $\chi(T,\omega)$ for a Hubbard model at half filling using Dynamical Mean-Field Theory, which is exact in infinite dimensions. Qualitatively distinct behavior is found in the different regions of the phase diagram: Mott insulator, Fermi liquid metal, bad metal, and a quantum critical region above the finite temperature critical point. The signature of the latter is $\omega/T$ scaling where $T$ is the temperature. Our results are consistent with previous results showing scaling of the dc electrical conductivity and are relevant to experiments on organic charge transfer salts.