Superconductivity of a new Ru-based alloy Ru3Sb1.75Sn5.25

We report the synthesis and superconductivity of a new Ru-based alloy Ru 3 Sb 1.75 Sn 5.25 . The single crystal and polycrystal samples were synthesized by the Sn-flux method and solid state reaction , respectively. The Ru 3 Sb 1.75 Sn 5.25 crystals were characterized by powder X-ray diffraction, electrical resistivity, magnetic susceptibility , and specific heat measurements. We find Ru 3 Sb 1.75 Sn 5.25 crystallize in the Ir 3 Ge 7 -type structure and exhibits superconductivity with onset transition temperature T c  = 4.2 K. Density functional theory calculation on Ru 3 Sb 1.75 Sn 5.25 unveils multiple peaks of density of states around the Fermi level , which may explain the emergence of superconductivity . Our study provides an example compound to explore the fascinating interplay of superconductivity , electronic band structure and paramagnetism in Ru-based superconductors .