Optical Sum Rule in Finite Bands

TL;DR

This paper reviews recent theoretical and experimental advances on the optical sum rule in finite electronic bands, highlighting its relation to interactions, temperature, impurity scattering, and superconductivity in high-Tc oxides.

Contribution

It provides a comprehensive review of recent progress in understanding the optical sum rule in finite bands, especially in high-Tc superconductors.

Findings

Optical sum varies with temperature and impurity scattering.

Sum rule relates to charge carrier kinetic energy.

Insights into superconducting state changes.

Abstract

In a single finite electronic band the total optical spectral weight or optical sum carries information on the interactions involved between the charge carriers as well as on their band structure. It varies with temperature as well as with impurity scattering. The single band optical sum also bears some relationship to the charge carrier kinetic energy and, thus, can potentially provide useful information, particularly on its change as the charge carriers go from normal to superconducting state. Here we review the considerable advances that have recently been made in the context of high $T_c$ oxides, both theoretical and experimental.