Superconductivity in novel Ge-based skutterudites: {Sr,Ba}Pt_4Ge_{12}

Combining experiments and ab initio models we report on $\mathrm{S}\mathrm{r}\mathrm{P}{\mathrm{t}}_4\mathrm{G}{\mathrm{e}}_{12}$ and $\mathrm{B}\mathrm{a}\mathrm{P}{\mathrm{t}}_4\mathrm{G}{\mathrm{e}}_{12}$ as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge-atoms. Below $T_c=5.35$ K, and 5.10 K for $\mathrm{B}\mathrm{a}\mathrm{P}{\mathrm{t}}_4\mathrm{G}{\mathrm{e}}_{12}$ and $\rm SrPt_4Ge_{12}$, respectively, electron-phonon coupled superconductivity emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-$p$ states dominate the electronic structure at the Fermi energy.