Entropy, frustration and large thermopower of doped Mott insulators on the fcc lattice

TL;DR

This study investigates how electronic frustration and strong correlations in doped Mott insulators on an fcc lattice lead to large thermopower, using dynamical mean-field theory to analyze the Hubbard model across various fillings and interaction strengths.

Contribution

It provides a comprehensive analysis of thermopower in the Hubbard model on the fcc lattice, highlighting the roles of frustration, doping, and interaction strength in large Seebeck coefficients.

Findings

Large low-temperature Seebeck coefficient near half-filling.

Maximum thermopower occurs with maximal electronic frustration.

High-frequency and Kelvin limits offer practical estimates of thermopower.

Abstract

Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the 3-dimensional fcc lattice over the whole range of fillings for intermediate and large interaction strength. Dynamical mean-field theory shows that when the density approaches half-filling, the fcc lattice at strong coupling exhibits a large low temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the DC limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling the thermopower can be understood on entropic grounds.