First principles study on the lattice dynamics and electron-phonon interaction of HfOs and HfRu compounds

Abstract

From the first principles calculation based on the plane-wave pseudopotential method of density functional theory, and the linear response technique, we have performed electronic structure, phonon and electron-phonon interaction of superconducting compounds HfOs and HfRu in B2 phase. The distribution of energy with different wave vector in the first Brillouin zone and conductive charge carriers (electrons and holes) at Fermi level are described by the electronic band structure and Fermi surfaces (FS), which reveal that both the compounds are metallic in nature. Phonon dispersion curves along with phonon density of states for both the compounds are calculated. Moreover, for the convincement of phonon calculation, we have described the eigen vector displacement of optical phonon modes at the zone centre which reveals that the computed phonon spectra are real. The interaction of electron with acoustic phonon modes and low-frequency optical phonon modes is responsible for superconductivity for both the compounds. The detailed discussion of superconductivity is given in terms of Eliashberg spectral function (α2F(ω)), electron phonon coupling constants (λ) and superconducting transition temperature (TC). The calculated value of λ is 0.41 and 0.33 for HfOs and HfRu. Using Allen Dynes formula the calculated superconducting transition temperature is 1.16 K and 1.163 K, with good agreement of experimental values.