Superconducting double transition in PrOs₄Sb₁₂ probed by local magnetization measurements and magneto-optical imaging

Double superconducting transition in PrOs₄Sb₁₂ 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 PrOs₄Sb₁₂ are discussed based on the local field inductions at multi-points.