Quantitative assessment of the universal thermopower in the Hubbard model

TL;DR

This study uses determinant quantum Monte Carlo to compare Hubbard model calculations with experimental thermopower measurements in cuprates, revealing qualitative and quantitative agreement and highlighting the role of interactions.

Contribution

It provides the first systematic quantitative comparison of Hubbard model predictions with experimental thermopower data in cuprates across multiple families.

Findings

Hubbard model reproduces doping dependence of thermopower

Thermopower upturn with decreasing temperature matches experiments

Sign change in thermopower occurs near zero temperature dependence of chemical potential

Abstract

As primarily an electronic observable, the room-temperature thermopower $S$ in cuprates provides possibilities for a quantitative assessment of the Hubbard model. Using determinant quantum Monte Carlo, we demonstrate agreement between Hubbard model calculations and experimentally measured room-temperature $S$ across multiple cuprate families, both qualitatively in terms of the doping dependence and quantitatively in terms of magnitude. We observe an upturn in $S$ with decreasing temperatures, which possesses a slope comparable to that observed experimentally in cuprates. From our calculations, the doping at which $S$ changes sign occurs in close proximity to a vanishing temperature dependence of the chemical potential at fixed density. Our results emphasize the importance of interaction effects in the systematic assessment of the thermopower $S$ in cuprates.