Adopting a Kim-type field dependent model, we calculate the current and flux density profiles of a thin disk-shaped superconducting film by extending the critical state model suggested by Mikheenko and Zhu et al. The results agree well with experimental data for the magnetic response of a disk YBa2Cu3O7-δ film in perpendicular magnetic field. The temperature dependence of J0 and H0 are also obtained and discussed.

考虑到有效钉扎势U（J）与临界电流密度的非线性关系,将U（J）展开为三级泰勒级数,最后推导出一个普遍适用于描述高温超导体磁弛豫的等温衰减方程,并用这一方程研究了具有高J c ,强钉扎的区域熔炼法制备YBa 2 Cu 3 O 6+x 的磁弛豫,而且对目前被普遍采用的几个钉扎模型进行了讨论.

Considering the nonlinear dependence of the effective pinning potential U(J) on the critical current Jc, a more general isothermal decay equation to describe the magnetization relaxation in high Tc superconductors was derived, which takes into account the first two nonlinear terms in the Taylor expansion. With this equation, the magnetization relaxation on zone-melted YBa2Cu3O6+x samples which show high Jc and strong flux pinning was studied; and three flux pinning models, i.e. Anderson-Kim model, collective pinning model and the logarithmic form of U(J) were discussed.