MEASUREMENTS OF CRITICAL CURRENTS AS A FUNCTION OF TEMPERATURE IN YBA2CU3O7-X THIN-FILMS - A COMPARATIVE-STUDY

The critical current density (J(c)) for zero magnetic field has been measured as a function of temperature in c-oriented thin layers of YBa2Cu3O7-x prepared by different synthesis methods. One direct and two indirect J(c)(T) methods were employed for each film: transport measurements on patterned film constrictions, DC remanent magnetization studies using the Bean model and non-linear AC screening analysis. Results from the indirect methods were calibrated against transport data. Possible origins of observed dependences are suggested and calibration procedures are discussed. The investigation demonstrated the feasibility of using AC screening analysis in rapid determinations of J(c)(T) close to T(c).