Abstract
To test the utility of the modified Kim-Anderson model for study of the magnetic response of ceramic superconductors, we measured ac complex susceptibilities xn=x'n-ix"n(n=1, 2, 3, 5, 7) of a single-crystal thin film Bi2Sr2CaCu2Oy, and attempted to simulate the results in the framework of this model. Analyses of xn, have shown that generation of the higher-harmonics can be reproduced pretty well, where the material parameters k and B0, the surface barrier ΔH and the lower critical field HCI involved were used as the fitting parameters. From the even-n harmonic susceptibility x2 which reflects the asymmetric nature of the magnetization curve, we foundthat the critical-current density Jc of the Bi2Sr2CaCu2Oy film depends sensitively on the local flux density Bi. This result is a provoking contrast to the Bi, dependence of Jc. for an YBa2Cu3Oy film.
