Role of the Dopant in the Superconductivity of Diamond

Abstract

We present an ab initio study of the recently discovered superconductivity of boron doped diamond within the framework of a phonon-mediated pairing mechanism. The role of the dopant, in substitutional position, is unconventional in that half of the coupling parameter $\lambda$ originates in strongly localized defect-related vibrational modes, yielding a very peaked Eliashberg ${\alpha }^{2}F(\omega )$ function. The electron-phonon coupling potential is found to be extremely large, and $T_C$ is limited by the low value of the density of states at the Fermi level. The effect of boron isotope substitution is explored.