Crossover from intrinsic to extrinsic pinning for YBa2Cu3O7 films

Critical current density properties for YBa2Cu3O7 films which have differen t pinning strength were measured as a function of magnetic field, temperatu re or magnetic field angle. We found that a kink anomaly appeared in the te mperature dependence of critical current densities J(c) and that the temper ature at which the anomaly appeared depended on the extrinsic pinning stren gth. The magnetic field and angular dependences of J(c) indicate that the a nomaly is due to the crossover from the intrinsic to the extrinsic pinning. Using a competition model of the intrinsic and extrinsic pinning, a kink a nomaly is explained successfully. (C) 1999 Cryogenic Association of Japan. Published by Elsevier Science Ltd. All rights reserved.