AC susceptibility for superconducting slab with regions of different critical-current densities

Based on the flux creep model, the temperature T and the amplitude of the AC field B-0 dependence of the complex AC susceptibility as a function of temperature are numerically calculated in a superconducting slab composed by three parts connected by two regions of lower critical-current density J(c) which characterize the non-uniform J(c) distributions in inhomogeneous superconductors. By a comparison with the analytical results of a homogeneous superconductor with a constant J(c), the numerical results show that the fundamental AC susceptibility of the composite slab is obviously different from the case of the homogeneous superconductor. (C) 2011 Elsevier Ltd. All rights reserved.