Transport criticality at Mott transition in a 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 behaviors and the importance of Drude weight changes over scattering rate variations.

Contribution

It provides a detailed analysis of optical conductivity near the Mott transition using cellular dynamical mean field theory, highlighting novel critical exponents and peak behaviors.

Findings

Drude weight change dominates transport near the Mott transition.

Emergence of an ingap peak in insulating phase connecting to Drude peak.

Power-law behavior of peak weights with a non-Ising universality class.

Abstract

We study electric transport near the Mott metal-insulator transition in a triangular-lattice Hubbard model at half filling. We calculate optical conductivity $\sigma(\omega)$ based on a cellular dynamical mean field theory including vertex corrections inside the cluster. Near the Mott critical end point, a Drude analysis in the metallic region suggests that the change in the Drude weight is important rather than that in the transport scattering rate for the Mott transition. In the insulating region, there emerges an "ingap" peak in $\sigma(\omega)$ at low $\omega$ near the Mott transition, and this smoothly connects to the Drude peak in the metallic region with decreasing Coulomb repulsion. We find that the weight of these peaks exhibits a power-law behavior upon controlling Coulomb repulsion at the critical temperature. The obtained critical exponent suggests that conductivity does not correspond to magnetization or energy density of the Ising universality class in contrast to several previous works.