Electron-phonon interaction and superconductivity in the multiband superconductor β-Bi2Pd

Abstract

We have investigated the structural, electronic, and vibrational properties of β-Bi2Pd in the body-centered tetragonal CaC2 structure using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. There are several electronic bands near the Fermi energy, with varying degrees of dispersive behaviour, which arise dominantly from Bi 6p orbitals and also from Bi 5d and Pd 5p orbitals. A critical assessment of the Eliashberg spectral function reveals that Bi-related vibrations couple strongly with the electrons at the multiband Fermi energy. By integrating the Eliashberg spectral function, the values of the average electron-phonon coupling and the logarithmic average frequency are determined to be 1.03 and 79.23 K, respectively. With these values, the Allen-Dynes formula suggests the BCS superconducting transition temperature of Tc = 5.5 K, in excellent agreement with the recently presented experimental value of 5.4 K.