Crossover from Intrinsic to Extrinsic Pinning for YBa2Cu3O7 Films

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, Jc, and that the temperature at which the anomaly appeared depended on the extrinsic pinning strength. The magnetic field and angular dependences of Jc 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.