Analysis of average transport critical current density of oxide superconductors deposited on a silver base

Abstract

Considering the resistivity of a silver base and the contact resistance of a silver base with a bulk superconductor, the dependence of average critical current density J(c)(D,H-a) of a high-T-c, oxide superconductor deposited oil a silver base on the sample dimension D and the applied magnetic field H-a is calculated using a generalized critical-state model, which was recently extended to low field by Chen and Yang [Physica C 224 (1994) 345]. The self-field effect of the average critical current was also taken into account in the model. Based on the generalized critical state model, new behaviors of J(c)(D, H-a) in the low-field range of H-c1 less than or equal to H-a much less than H-c2 are obtained. In addition, a constant J(c)(D, H-a) for 0 less than or equal to H-a less than or equal to H-c1 is obtained, which is different from the results derived from a model that does not include the self-field effect. However, these theoretical results can be fitted to the experimental data to obtain some important macroscopic material parameters and may be used to interpret the dimension effect of transport J(c) of a high-T-c oxide superconductor deposited on a silver base.