AC susceptibility of high T-c superconductor Tl0.8Pb0.2Bi0.2Sr1.6Ba0.4Ca2Cu3Ox using a critical state model

The Anderson-Kim model is employed to calculate the temperature and AC magn etic field dependence of the complex susceptibility, chi = chi' + i chi", o f high T-c superconductor Tl0.8Pb0.2Bi0.2Sr1.6Ba0.4Ca2Cu3Ox. Intergranular Josephson vortices sweep in and out of the weak-link network, while intragr anular Abrikosov vortices move in and out of the superconducting grains, bo th causing bulk pinning hysteresis loss. The calculated chi' and chi" are c onsistent with experimental data very well by considering the proper volume fraction of superconducting grains and intergranular region. Using field d ependence of critical current density obtained from fitting parameter, the property of intergranular region is discussed and the intergranular lower c ritical field H-clJ is determined. (C) 2001 Elsevier Science B.V. All right s reserved.