Contactless estimation of critical current density in thin superconducting films and its temperature dependence using ac magnetic measurements

摘要

We have measured magnetic response of second-generation high temperaturesuperconductor YBa2Cu3Ox wire and Nb thin film in perpendicular ac field as afunction of temperature. We compare experimental complex ac susceptibility tothe calculated susceptibility based on the model of Bean's critical-stateresponse in two-dimensional (2D) disk in perpendicular field. The harmonicanalysis is needed for comparison between the model and the experimental data.We present a method of linking model and experimental susceptibility. Goodagreement of experimental susceptibility with model susceptibility of 2D diskallows contactless estimation of critical depinning current density and itstemperature dependence.