Double magnetic transition in pr_0.5Sr_0.5CoO₃

We report studies of polycrystalline samples of the metallic ferromagnet Pr_0.5Sr_0.5CoO₃ through measurements of the magnetization, ac magnetic susceptibility, resistivity, and specific heat. We find an unusual anomaly around T_A=120 K, much below the ferromagnetic transition (T_C=226±2 K). The anomaly is manifested in field cooled magnetization as a downward step in low field(H∼0.05 T. The anomaly cannot be easily attributed to antiferromagnetic ordering, but may correspond to asecond ferromagnetic transition or an alteration of the ferromagnetic state associated with orbital ordering.