Electron and phonon band-structure calculations for the antipolar SrPt$_{3}$P antiperovskite superconductor: Evidence of low-energy two-dimensional phonons

摘要

SrPt3P has recently been reported to exhibit superconductivity with Tc = 8.4K. To explore its superconducting mechanism, we have performed electron andphonon band calculations based on the density functional theory, and found thatthe superconductivity in SrPt3P is well described by the strong couplingphonon-mediated mechanism. We have demonstrated that superconducting chargecarriers come from pd\pi-hybridized bands between Pt and P ions, which coupleto low energy (~ 5 meV) phonon modes confined on the ab in-plane. Thesein-plane phonon modes, which do not break antipolar nature of SrPt3P, enhanceboth the electron-phonon coupling constant \lambda and the critical temperatureTc. There is no hint of a specific phonon softening feature in the phonondispersion, and the effect of the spin-orbit coupling on the superconductivityis found to be negligible.