Superconducting Double Transition in PrOs4Sb12Probed by Local Magnetization Measurements and Magneto-Optical Imaging

Double superconducting transition in PrOs 4 Sb 12 has been studied carefully by performing the local magnetization measurements using micro-Hall probe and the magneto-optical imaging. Local magnetization curves for each element of the Hall probe reveal that there exists a significant difference in the transition temperature at each point; two phases which give different T c 's are stabilized in the crystal. Magneto-optical imaging at T < T c2 and T c2 < T < T c1 also reveals a non-uniform superconducting nature. The characteristics of superconducting double transition in PrOs 4 Sb 12 are discussed based on the local field inductions at multi-points.