On the Difference of pinning potentials for thermally activated flux creep estimated by resistive and magnetization measurements in high T_c superconducting films

A new measuring method of the pinning potential, U_c, for thermally activated flux creep is proposed. By this type of resistive measurements, we can obtain the observed data of U_c even in the low field region, where the direct comparison with the observed data from the magnetization measurements is possible. The observed results of U_c by the present resistive measurements for a c-axis oriented CVD film of YBa₂Cu₃O₇ at 77.3K were 0.05eV at 3T and 0.07eV at 2T, while U_c from the magnetization measurement was 0.09eV at 1T. The present results clearly resolved a strange puzzle that the values of U_c, which have been inferred from the observed data of the existing resitive method at higher temperatures by using the Malozemoff type of temperature dependence of U_c, are usually more than ten times larger than those obtained from the magnetization measurements. It is also pointed out that the use of Fujiyoshi type of temperature dependence of U_c leads to the values of U_c with the same order of magnitude as those form the magnetization measurements.