Optical Conductivity in Mott-Hubbard Systems

TL;DR

This paper investigates how spectral weight in optical spectra of strongly correlated electron systems varies with temperature and interaction strength, using dynamical mean field theory and experimental data from V2O3.

Contribution

It provides a theoretical prediction of anomalous spectral weight enhancement with temperature and confirms this with experimental measurements in V2O3.

Findings

Spectral weight increases anomalously with temperature in correlated metals.

Experimental data from V2O3 supports the theoretical prediction.

Optical conductivity anomalies relate to proximity to a phase crossover.

Abstract

We study the transfer of spectral weight in the optical spectra of a strongly correlated electron system as a function of temperature and interaction strength. Within a dynamical mean field theory of the Hubbard model that becomes exact in the limit of large lattice coordination, we predict an anomalous enhancement of spectral weight as a function of temperature in the correlated metallic state and report on experimental measurements which agree with this prediction in $V_2O_3$. We argue that the optical conductivity anomalies in the metal are connected to the proximity to a crossover region in the phase diagram of the model.