Infrared Conductivity of Cuprate Metals: Detailed Fit Using Luttinger Liquid Theory

TL;DR

This paper demonstrates that the infrared conductivity behavior of cuprate metals in the normal state can be accurately modeled using Luttinger Liquid theory, revealing a frequency-independent phase angle and a specific singularity exponent.

Contribution

It provides a detailed fit of infrared conductivity data using Luttinger Liquid theory, linking experimental observations to theoretical charge-spin separation in cuprates.

Findings

Phase angle of conductivity is frequency-independent.

The singularity exponent at the Fermi surface is approximately 0.15.

The model fits experimental data from hundreds to over 5000 cm$^{-1}$.

Abstract

Measurements of infrared conductivity in the normal state of the cuprate layer metals show a characteristic behavior in the plane of the layers which is in essential agreement among many experiments. A simple parametrization of this behavior, proposed originally by Collins and Schlesinger, and exploited by N. Bontemps and her group, which gives an adequate fit over frequencies from a few hundred cm$^{-1}$ to $>5000 $ cm$^{-1}$, is that the phase angle of the complex conductivity is independent of frequency. This fit is shown to be a natural consequence of Luttinger Liquid theory with charge-spin separation, and determines the exponent of the singularity at the Fermi surface to be $\sim .15\pm .05$.