Microwave losses of bulk CaC6

TL;DR

This study investigates the microwave surface resistance of CaC6, revealing it as a weakly-coupled, fully gapped superconductor with a transition temperature of 11.5 K, using high-frequency measurements to understand its quasiparticle behavior.

Contribution

First microwave analysis of CaC6 showing its superconducting gap structure and pairing nature, providing insights into its quasiparticle dynamics.

Findings

CaC6 is a weakly-coupled, fully gapped superconductor.

Surface resistance measurements confirm superconductivity at 11.5 K.

Microwave data yields information on quasiparticle density and pairing.

Abstract

We report a study of the temperature dependence of the surface resistance RS in the graphite intercalated compound (GIC) CaC6, where superconductivity at 11.5 K was recently discovered. Experiments are carried out using a copper dielectrically loaded cavity operating at 7 GHz in a "hot finger" configuration. Bulk CaC6 samples have been synthesized from highly oriented pyrolytic graphite. Microwave data allows to extract unique information on the quasiparticle density and on the nature of pairing in superconductors. The analysis of RS(T) confirms our recent experimental findings that CaC6 behaves as a weakly-coupled, fully gapped, superconductor.