Roles of optical phonons and logarithmic profile of electron-phonon coupling integration in superconducting Sc0.5Y0.5H6 superhydride under pressures

Abstract

The stable structure of symmetrically Sc/Y-substituted hexahydride Sc0.5Y0.5H6 under high pressures is theoretically reported herein to superconduct with maximum Tc of 127 K, as supported by analyses of the electronic band structure, Fermi surface topologies, phonon dispersion, and the Eliashberg spectral function. We also expatiate on an alternative approach in describing the nature of Tc under pressures, i.e. the bandwidth function as an approximation of the spectral function (α2F) for Sc0.5Y0.5H6. Being a special case, the bandwidth function is derived from an analytic solution for the α2F function given constraints arising from the characteristics of the function itself. The consistency between the DFT-obtained α2F function and that of the proposed model suggests the dominant role played by the cutoff frequency for the optical modes in affecting Tc.