Comparison between critical current density in thin superconducting films estimated from temperature and field dependence of ac susceptibility

We have measured an ac magnetic susceptibility of recent second generation high temperature superconductor wires (coated conductor tapes) both as a function of an amplitude of an applied ac magnetic field at fixed temperatures and as a function of temperature at the fixed amplitudes. We find that data acquired by both methods are well described by ac susceptibility calculated on the basis of the Clem-Sanchez model to a response of thin superconducting disks in the Bean critical state to an applied perpendicular ac magnetic field. We show how to link the empirical data dependent on the field amplitude or temperature with theoretical data dependent on the ratio between the critical current density and field amplitude. The critical depinning current densities and its temperature dependence found by both methods are in good agreement. We discuss and compare accuracy and time saving of both methods.