AC susceptibility response and critical current density of a nominal Hg1−xPbxBa2Ca2Cu3O8+δ superconductor for different critical state models

Abstract

Various critical state models used to estimate the critical current density Jc of the granular superconductor were studied. Results of such estimation were compared with the results from the AC susceptibility measurements of the Hg0.69Pb0.31Ba2Ca2Cu3O8+δ sample. By using least-square analyses, it is found that all these critical state models are generally agreed with the experimental data quite well. The theoretical results of Jc for different critical state models were discussed. In order to estimate the critical current density Jc, the parameters B0 and Bp involved in the critical current density expression were extracted by using a specific technique. It was shown that the Jc vs T curves for different critical state models are close one to another within the high temperature range close to Tc of the superconductor.