Probing physical properties and superconductivity of noncentrosymmetric superconductors LaPtGe and LaPtGe3: A first-principles study

Abstract

In this study, both scalar and full-relativistic ab initio pseudopotential calculations have been actualized on the physical and superconducting properties of noncentrosymmetric superconductors LaPtGe and LaPtGe3 in order to discern the effect of spin-orbit coupling. The spin-orbit coupling makes slightly more effect on the physical properties of LaPtGe than those of LaPtGe3 since the near-Fermi band structure of the former is dominated by d shell electrons rather than p shell electrons as observed in the latter. For both compounds, the splitting into sub-bands arising from the antisymmetric spin-orbit effect remains small around the Fermi level. The phonon spectrum and Eliashberg spectral function of LaPtGe are weakly affected by the inclusion of spin-orbit coupling, while this coupling makes almost no effect on them for LaPtGe3. Therefore, we can conclude that superconductivity in both noncentrosymmetric superconductors has s-wave pairing symmetry and its mechanism arises from the electron-phonon interaction in the medium coupling limit for LaPtGe and the weak-coupling limit for LaPtGe3.