Crossover from Intrinsic to Extrinsic Pinning for YBa₂Cu₃O₇ Films

Abstract

Critical current density properties for YBa₂Cu₃O₇ films which have different pinning strengths were measured as a function of magnetic field, temperature or magnetic-field angle. We found that a kink anomaly appeared in the temperature dependence of critical current densities, J_c, and that the temperature at which the anomaly appeared depended on the extrinsic pinning strength. The magnetic field and angular dependences of J_c indicate that the anomaly is due to the crossover from intrinsic to extrinsic pinning. Using a competition model of intrinsic and extrinsic pinning, a kink anomaly is explained successfully.