Collective modes and electromagnetic response of a chiral superconductor

TL;DR

This paper investigates the electromagnetic response of a clean chiral p-wave superconductor, revealing that collective modes significantly reduce the Hall response and exhibit unusual coupling to external fields, challenging previous theoretical predictions.

Contribution

It provides a detailed analysis of collective modes and their impact on the electromagnetic response, offering new insights into chiral superconductor behavior and experimental observations.

Findings

Hall response is much smaller than earlier predictions

Collective modes are not purely longitudinal and couple to transverse fields

Results challenge previous explanations of Kerr effect measurements

Abstract

Motivated by the recent controversy surrounding the Kerr effect measurements in strontium ruthenate \cite{xia:167002}, we examine the electromagnetic response of a clean chiral p-wave superconductor. When the contributions of the collective modes are accounted for, the Hall response in a clean chiral superconductor is smaller by several orders of magnitude than previous theoretical predictions and is too small to explain the experiment. We also uncover some unusual features of the collective modes of a chiral superconductor, namely, that they are not purely longitudinal and couple to external transverse fields.