Optical sum rule anomalies in the cuprates: interplay between strong correlation and electronic bandstructures

TL;DR

This paper investigates the anomalies in optical sum rules in high-temperature cuprate superconductors, focusing on how strong correlations and bandstructure features like Van-Hove singularities influence temperature dependence.

Contribution

It demonstrates through Dynamical Mean-Field Theory that electron correlations and Van-Hove singularities compete, affecting optical sum rule anomalies in cuprates.

Findings

Electron-electron correlations enhance temperature dependence of sum rules.

Van-Hove singularities also influence sum rule anomalies.

The two effects are found to compete rather than cooperate.

Abstract

We theoretically analyze some of the anomalies of the optical sumrules in the high-temperature superconductors. In particular we address the particularly strong dependence on temperature of the sumrule in the normal state. Both electron-electron correlations and the presence of a Van-Hove singularity have been shown to enhance such a dependence. Here we consider both effects simultaneously by means of Dynamical Mean-Field Theory for a two dimensional Hubbard model with realistic parameters for different cuprates, and we find that the two effects are not cooperative, as they appear to compete one another in the region of parameters relevant for the experiments.