Electrodynamics of Correlated Electron Materials

TL;DR

This review discusses the electromagnetic response of various correlated electron materials, emphasizing experimental techniques and universal trends in understanding strong electronic correlations.

Contribution

It provides a comprehensive overview of optical and spectroscopic studies across diverse correlated systems, highlighting universal behaviors and current theoretical challenges.

Findings

Identification of universal optical response trends

Correlation between experimental data and theoretical models

Insights into the evolution of strong correlation understanding

Abstract

We review studies of the electromagnetic response of various classes of correlated electron materials including transition metal oxides, organic and molecular conductors, intermetallic compounds with $d$- and $f$-electrons as well as magnetic semiconductors. Optical inquiry into correlations in all these diverse systems is enabled by experimental access to the fundamental characteristics of an ensemble of electrons including their self-energy and kinetic energy. Steady-state spectroscopy carried out over a broad range of frequencies from microwaves to UV light and fast optics time-resolved techniques provide complimentary prospectives on correlations. Because the theoretical understanding of strong correlations is still evolving, the review is focused on the analysis of the universal trends that are emerging out of a large body of experimental data augmented where possible with insights from numerical studies.