Electron-phonon coupling in a boron-doped diamond superconductor

Abstract

The electronic structure, lattice dynamics, and electron-phonon coupling of the boron-doped diamond are investigated using the density-functional supercell method. Our results indicate the boron-doped diamond is a phonon mediated superconductor, confirming previous theoretical conclusions deduced from the calculations employing the virtual-crystal approximation. We show that the optical-phonon modes involving B vibrations play an important role in the electron-phonon coupling. Different from previous theoretical results, our calculated electron-phonon coupling constant is 0.39 and the estimated superconducting transition temperature ${T}_{c}$ is $4.4\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for the boron-doped diamond with 2.78% boron content using the Coulomb pseudopotential $\ensuremath{\mu}*=0.10$, in excellent agreement with the experimental result.