Analysis of field dependence of AC susceptibility due to intergrain coupling in the absence of vortices

Abstract

Intergrain features observed in the AC magnetic susceptibility of polycrystalline YBCO, measured in very low AC field, are utilized to extract the field and temperature dependence of electrodynamic parameters involved in intergrain shielding. A nonvortex model for granularity is used to simulate χ'(T) and χ"(T),which is found to fit well with the experimental data. Calculated intergranular resistance, R(T), increases with applied field. This shows that at higher fields, grains does not easily achieved phase coherence, which results for the intergrain current to experienced higher resistance. Inductance, L, is found to increase linearly with field, showing that area over which intergranular shielding current loop flow, increases with field.