Lattice dynamics, transport and superconducting properties of Ba-substituted Sr3SnO

We have explored the lattice dynamics, transport and superconducting properties of Ba-substituted Sr3SnO (Sr3-xBaxSnO, x = 0, 1, 2) using density functional theory (DFT) and density functional perturbation theory (DFPT). All the studied alloys show good dynamical stability. These Ba-substituted systems show metallic band structure due to the mixing of Sr-4d and Ba-5d with Sn-5p orbitals. According to Migdal-Eliashberg theory the calculated electron-phonon coupling constant and logarithmic-averaged phonon frequency for Sr2BaSnO are λ = 0.24 and ωln = 124.55 K, respectively and the corresponding Tc = 0.6 K while it is 0.2 K for SrBa2SnO. Our analysis reveals that phonon softening by Ba-substitution is responsible for superconductivity in these alloys.