specific heat measurements. The characteristic anomaly at the superconducting transition (T
c= 11.4 K) indicates clearly the bulk nature of the superconductivity. The temperature and
magnetic field dependence of the electronic specific heat are consistent with a fully gapped
superconducting order parameter. The estimated electron-phonon coupling constant is λ=
0.70±0.04, suggesting that the relatively high T c of CaC 6 can be explained within the …