Supercurrent lengthscale in sintered YBCO and critical state model

Magnetization measurements on sintered YBa 2 Cu 3 O 7-y in two geometries (slab and cylinder) show the coexistence of two transport mechanisms; intergranular and intragranular currents. Both mechanisms can be explained in the framework of the critical state model. Using a simple law for the critical current versus magnetic field dependence, it is possible to calculate the magnetization and the in-phase and out-of-phase AC susceptibility and the agreement with the experimental data is good. Magnetization measurements on tubular samples have been performed too; these measurements, together with χ AC measurements allow determination of the dimensions of magnetized regions