The superconducting properties of the graphite intercalation compound CaC 6, available as high-quality c-axis-oriented polycrystals, were investigated through muon-spin spectroscopy measurements. An unconventional TF-μSR procedure, applicable to superconductors characterized by close-lying critical fields, was successfully adopted for measuring the muon-spin relaxation rates. Field-dependent measurements provide a value λ ab (0)= 62 (4) nm for the in-plane magnetic field penetration depth, κ= 1.4 (2) for the GL parameter, and hint at the presence of a slight gap anisotropy in the ab plane. The dependence of relaxation on temperature confirms the s-wave character of CaC 6 superconductivity, with an average zero-temperature superconducting gap of 2.1 (1) meV.
1 Jan 2011
Volume: 13 Issue: 1 Pages: 013038
New Journal of Physics