Superconductivity in the Mn₅Si₃-type Zr ₅Sb₃ system

We report the discovery of superconductivity at 2.3 K in Zr ₅Sb₃, the first superconducting member in the large compound family of the Mn₅Si₃-type structure. Transport, magnetic, and calorimetric measurements clearly demonstrate bulk superconductivity for Zr₅Sb₃ and suggest it to be a possible phonon-mediated BCS superconductor with a relatively large density of states at the Fermi level associated with the d electrons of Zr and substantially larger electron-phonon coupling compared to the Sn counterpart compound Zr₅Sn₃ from band structure calculations. More superconductors with even higher transition temperatures are expected to be found in this family of compounds.