Discovery of a new strong-coupling superconductor Y₇Ru₄InGe₁₂ by indium flux

Compounds containing rare earth, transition metal and germanium elements can exhibit interesting phenomena such as charge density wave, complex magnetism and superconductivity. Using indium flux makes it possible to synthesis new compounds under a relative low temperature. Here we discovered a new superconductor Y₇Ru₄InGe₁₂ with T_c ~ 5.8 K grown from the indium flux, which is confirmed by resistivity, magnetization and specific heat measurements. It is a type-II superconductor and its upper critical fields are estimated to be 5.4 and 2.7 T along and perpendicular to the c axis, respectively. The estimated mean free path along the c axis is ~ 29 Å, much smaller than the superconducting coherence length ~ 172 Å, putting it in a dirty limit regime. The specific heat jump of this superconductor ΔC/γ_eT_c ≈ 2.4 is much larger than the BCS theoretical value 1.43, pointing to a strong-coupling scenario. A new polymorphism of LuRuGe and several trials to synthesize isostructural compounds of Y₇Ru₄InGe₁₂ by replacing the rare earth elements will also be presented in this talk.