The effect of spin orbit interaction for superconductivity in the noncentrosymmetric superconductor CaIrSi3

Abstract

We have carried out an ab initio study of the electronic, vibrational and electron-phonon interaction properties of the body-centred tetragonal CaIrSi3 by employing the density functional theory, a linear-response formalism, and the plane-wave pseudopotential method. The electronic structure and phonon dispersion relations of this material have been analyzed with and without the inclusion of spin-orbit interaction (SOI). Our electron-phonon interaction results reveal that Si-related phonon modes are more involved in the process of scattering of electrons than the remaining phonon modes due to considerable existence of the Si 3p states near the Fermi level. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter is found to be 0.58 which compares very well with its experimental value of 0.56. Using the calculated value of λ, the superconducting critical temperature (Tc) for CaIrSi3 is found to be 3.20 K which is in good accordance with its experimental value of 3.55 K. Furthermore, we have shown that the effect of SOI on the values of λ and Tc is very small.