Theoretical investigation of superconductivity in SrAuSi3 and SrAu2Si2

Abstract The structural and electronic properties of BaNiSn 3 -type SrAuSi 3 and ThCr 2 Si 2 -type SrAu 2 Si 2 have been investigated by using the planewave pseudopotential method and the density functional theory. The electronic structures and phonon dispersion relations of these two materials have been analyzed with and without the inclusion of spin–orbit interaction, and similarities and differences highlighted. By integrating the Eliashberg spectral function α 2 F ( ω ), the average electron–phonon coupling parameter is determined to be λ =0.47 for SrAuSi 3 and 0.42 for SrAu 2 Si 2 . The largest contribution to the electron–phonon coupling for SrAuSi 3 comes from the Si p electrons near the Fermi energy and Si-related vibrations. Using a reasonable value of μ * = 0.12 for the effective Coulomb repulsion parameter, the superconducting critical temperature T c for SrAuSi 3 is found to be 1.47 K which compares very well with its experimental value of 1.54 K.