FLUX-CREEP CHARACTERISTICS IN THE PRESENCE OF A PINNING DISTRIBUTION FOR Y1BA2CU3O7-DELTA SUPERCONDUCTING THIN-FILMS

Nonlinear current-voltage (I-V) characteristics in Y1Ba2Cu3O7-delta th in films have been studied for flux creep taking into account the inho mogeneous pinning strength. By measuring-the frequency dependence of t he I-V characteristics, we separated the flux creep and flux flow prop er ties. I-V curves split in the low electric-field region depending o n the measurement frequency. From the frequency dependant I-V curves, we obtained the maximum creep field, at which flux creep crossed over to flux flow. By use of the Weibull function, which describes the depi nning probability the pinning distribution from the flow nonlinearity obtained from ac measurements. The flux creep electric-field was calcu lated by integrating the Arrhenius equation according to the pinning d istribution. The obtained expressions agreed well with the measurement over more than six decades of electric-field.