Theory of the Optical Conductivity in the Cuprate Superconductors

TL;DR

This paper investigates the optical conductivity in cuprate superconductors using the nearly antiferromagnetic Fermi liquid model, explaining experimental anomalies through anisotropic scattering rates and marginal Fermi liquid behavior.

Contribution

It demonstrates that NAFL theory accounts for the anomalous optical properties in cuprates across different doping levels, supported by numerical calculations matching experimental data.

Findings

NAFL theory explains anisotropic scattering in cuprates.

Optical conductivity follows Marginal Fermi Liquid behavior.

Results align with experimental observations in various compounds.

Abstract

We present a study of the normal state optical conductivity in the cuprate superconductors using the nearly antiferromagnetic Fermi liquid (NAFL) description of the magnetic interaction between their planar quasiparticles. We find that the highly anisotropic scattering rate in different regions of the Brillouin zone, both as a function of frequency and temperature, a benchmark of NAFL theory, leads to an average relaxation rate of the Marginal Fermi Liquid form for overdoped and optimally doped systems, as well as for underdoped systems at high temperatures. We carry out numerical calculations of the optical conductivity for several compounds for which the input spin fluctuation parameters are known. Our results, which are in agreement with experiment on both overdoped and optimally doped systems, show that NAFL theory explains the anomalous optical behavior found in these cuprate superconductors.