Investigation of Anomalous Magnetic Transition in Pr0.5Sr0.5CoO3

Polycrystalline perovskite cobalt oxides Pr0.5Sr0.5CoO3 were prepared by the sol-gel method. We mainly study the anomalous magnetic transition of Pr0.5Sr0.5CoO3. We report the investigations of polycrystalline samples of the metallic ferromagnetic material Pr0.5Sr0.5CoO3 through measurements of X-ray diffraction, the magnetization, and the resistivity. We found an unusual anomaly around T (A)=120 K, much below the ferromagnetic transition (T (C)=228 K). Further using the variable temperature X-ray diffraction and electron spin resonance (ESR) measurements, we found that as the temperature goes down, the crystal structure changes obviously at T (A)=120 K. We show that this actually results in anomalous magnetic transition.