Complex Harmonic Susceptibilities of Bi_2Sr_2Ca_2Cu_3O_y with Different Critical-Current Density

摘要

We measured complex harmonic susceptibilities x_n = x'_n - ix_n"(n = 1,2,3) of sintered superconductors with different critical current densities J_c, and analyzed the observed X_n in the framework of the Kim-Anderson critical-state model. X_n were measured by employing a Hartshorn bridge, where an external ac field superimposed on the Earth's field was applied along the sample axis. Analysis the observed X_n have revealed that the material parameters involved in the model closely correlate to J_c. In addition, the behavior of X_2 well corresponds to the values of J_c, suggesting the possibility of magnetic evaluations of J_c.