Anisotropic superconductivity in bulk CaC6

The intercalated graphite superconductor CaC6 with Tc∼11.5K has been characterized with angular dependent magnetoresistance measurements. Above Tc, the interplane resistivity can be fitted to the Bloch-Grüneisen model providing a Debye temperature of θD=175K. From these parameters, the McMillan formula yields an electron-phonon coupling constant λ∼1.1, placing this material in the intermediate-to-strong coupling regime. For 1.4K