Anomalous magnetic and superconducting properties in a Ru-based double perovskite

We have studied the double perovskite [1] structure Sr2Y(Ru1-xCux)O6 system. The parent compound is an antiferromagnetic insulator with Neel temperature ∼ 26 K. Partially substituted the Ru ion by Cu the compounds increase their conductivity drastically and eventually become superconducting. More intriguingly is the observation of the coexistence of superconductivity and magnetic ordering. The superconducting transition temperature Tc and the magnetic ordering temperature Tm are of the same order. The observed magnetic structure and superconductivity of these compounds can be understood in terms of a plausible theoretical model based on the double exchange idea.