Superfluid Inhomogeneity and Microwave Absorption in Model High-T_c Superconductors

TL;DR

This paper models how inhomogeneities in superfluid density, from disorder or charge density waves, cause additional microwave absorption in high-T_c superconductors, linking theory to recent experimental observations.

Contribution

It introduces a simple model to quantify microwave absorption due to superfluid inhomogeneity and connects predictions with recent experimental data.

Findings

Inhomogeneities cause finite-frequency absorption.

Both disorder and charge density waves contribute to absorption.

Model aligns with recent THz measurements on BSCCO.

Abstract

We investigate the microwave absorption arising from inhomogeneity in the superfluid density of a model high-T_c superconductor. Such inhomogeneities may arise from a wide variety of sources, including quenched random disorder and static charge density waves such as stripes. We show that both mechanisms will inevitably produce additional absorption at finite frequencies. We present simple model calculations for this extra absorption, and discuss applications to other transport properties in high-T_c materials. Finally, we discuss the connection of these predictions to recent measurements by Corson et al. of absorption by the high-temperature superconductor BSCCO in the THz frequency regime.