Transport properties of strongly correlated metals:a dynamical mean-field approach

TL;DR

This paper investigates how the transport properties of strongly correlated metals change with temperature using dynamical mean-field theory, revealing a crossover from coherent to incoherent excitations and non-monotonic behavior in resistance and thermopower.

Contribution

It applies dynamical mean-field theory to study temperature-dependent transport in a frustrated Hubbard model, highlighting the crossover from Fermi liquid to incoherent regimes.

Findings

Resistance exceeds Mott-Ioffe-Regel limit at high temperatures

Thermopower shows a peak indicating quasiparticle destruction

Absence of Drude peak in optical conductivity at high temperatures

Abstract

The temperature dependence of the transport properties of the metallic phase of a frustrated Hubbard model on the hypercubic lattice at half-filling are calculated. Dynamical mean-field theory, which maps the Hubbard model onto a single impurity Anderson model that is solved self-consistently, and becomes exact in the limit of large dimensionality, is used. As the temperature increases there is a smooth crossover from coherent Fermi liquid excitations at low temperatures to incoherent excitations at high temperatures. This crossover leads to a non-monotonic temperature dependence for the resistance, thermopower, and Hall coefficient, unlike in conventional metals. The resistance smoothly increases from a quadratic temperature dependence at low temperatures to large values which can exceed the Mott-Ioffe-Regel value, hbar a/e^2 (where "a" is a lattice constant) associated with mean-free paths less than a lattice constant. Further signatures of the thermal destruction of quasiparticle excitations are a peak in the thermopower and the absence of a Drude peak in the optical conductivity. The results presented here are relevant to a wide range of strongly correlated metals, including transition metal oxides, strontium ruthenates, and organic metals.