Effects of nonmagnetic impurities on optical conductivity in strongly correlated systems

TL;DR

This paper investigates how nonmagnetic impurities affect optical conductivity in strongly correlated antiferromagnetic systems, predicting a low-frequency peak due to resonant scattering and a high-frequency peak from electron interactions, aligning with experimental data.

Contribution

It introduces a detailed analysis of impurity effects on optical conductivity using Lanczos exact diagonalization, revealing specific peak features consistent with experimental observations.

Findings

Resonant scattering causes a low-frequency peak in optical conductivity.

High-frequency broad peak results from Heisenberg interactions.

Predictions align with observed optical conductivity in cuprate materials.

Abstract

Effects of nonmagnetic impurities on optical conductivity in the systems of antiferromagnetically correlated electrons are examined based on the Lanczos exact diagonalization scheme. As a result of resonant scattering a low-frequency peak in the optical conductivity is predicted to occur in the presence of the nonmagnetic impurities, which is consistent with the observed normal-state optical conductivity of ${\rm YBa_2}({\rm Cu}_{1-x}{\rm Zn}_x)_3{\rm O}_{7-\delta}$. In addition, a relatively high and broad peak is found to occur at a high frequency region as a consequence of the Heisenberg interaction between electrons, in agreement with observation in the peak position.