Superconductivity from Site-Selective Ru Doping Studies in Zr₅Ge₃ Compound

Systematical doping studies have been carried out to search for the possible superconductivity in the transition metal doped Zr₅Ge₃ system. Superconductivity up to 5.7 K is discovered in the Ru doped Zr₅Ge₂․₅Ru₀․₅ sample. Interestingly, with the same Ru doping, superconductivity is only induced with doping at the Ge site, but remains absent down to 1.8 K with doping at the Zr site or interstitial site. Both magnetic and transport studies have revealed the bulk superconductivity nature for Ru doped Zr₅Ge₂․₅Ru₀․₅ sample. The high upper critical field, enhanced electron correlation, and extremely small electron-phonon coupling, have indicated possible unconventional superconductivity in this system, which warrants further detailed theoretical and experimental studies.