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

TL;DR

This study uses density functional theory to analyze the electron and phonon structures of SrPt3P, revealing low-energy in-plane phonons that mediate strong-coupling superconductivity without phonon softening or significant spin-orbit effects.

Contribution

It provides detailed insights into the phonon-mediated superconducting mechanism in SrPt3P, highlighting the role of low-energy in-plane phonons and hybridized electronic bands.

Findings

Superconductivity is driven by strong electron-phonon coupling.

Low-energy (~5 meV) in-plane phonons enhance Tc.

Spin-orbit coupling has negligible effect on superconductivity.

Abstract

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