Transport criticality in triangular lattice Hubbard model

TL;DR

This paper investigates the electric transport properties near the Mott transition in a triangular lattice Hubbard model, revealing critical behavior of optical conductivity and differences in critical exponents.

Contribution

It introduces a cellular dynamical mean field theory approach with vertex corrections to analyze optical conductivity across the Mott transition on a triangular lattice.

Findings

Drude peak connects smoothly to an ingap peak across the transition

Optical weight exhibits power-law critical behavior near the critical point

Critical exponent differs from thermodynamic exponents

Abstract

We study electric transport near the Mott metal-insulator transition. Optical conductivity of the half-filled Hubbard model on a triangular lattice is calculated based on a cellular dynamical mean field theory including vertex corrections inside the cluster. By investigating the spectrum at low frequencies, we find that a Drude peak on the metallic side smoothly connects to an "ingap" peak on the insulating side. The optical weight of these peaks exhibits a critical behavior with power-law near the Mott critical end point, $|D-D^*|\propto|U-U^*|^{1/\delta}$. We find that the critical exponent $1/\delta$ differs from the exponents in the thermodynamics.