Long Josephson junctions modulated by defects and superconducting microdomains in YBCO thin films

The critical current J(c) of superconducting films is about two order of ma gnitude larger than that of single crystals. The dependence of such J(c) on field depends on the presence and distribution of defects. We speculate th at High Temperature Superconducting (HTS) films can be modeled as an agglom eration of islands coupled via Josephson contacts and then considered as a network of Long Josephson Junctions (LJJ) between superconducting islands. In order to check this hypothesis we further developed a model firstly intr oduced by Fehrenbacher based on the modulation of critical current densitie s in LJJ by means of suitable distribution of defects. The defects act by m odulating the coupling energy of the junction. Critical current densities a re calculated in the case of periodic and random defect distributions.