MAGNETIC-FIELD DEPENDENCE OF THE AC SUSCEPTIBILITY IN ANTIGRANULOCYTES YBA2CU3O7 - DATA AND MODELS

For a sintered rod of YBa2Cu3O7 at 78.3 K, detailed data are reported for the complicated dependence of the ac susceptibility approximately-chi = chi' - i-chi'' on applied ac and dc fields, ascribed to the inter- and intragranular components of the material. The intergranular data are understood in detail by a modified critical-state model, assuming a critical current density J(c)(H) approximately H-2. Approximately-chi(H(dc)) also displays hysteresis which is not readily explicable by this model.