Transport Properties of Granular High-TC Superconductors
  We report on the application of the Resistively Shunted Junction (RSJ) model to granular high-TC superconductors. Some derived predictions of the RSJ model are applied to a set of superconducting granular samples which can be considered as a network of Josephson junctions. The investigated samples belong to both hole-doped Y1-xPrxBa2Cu3O7-d (x = 0.0, 0.35, and 0.45) and the electron-doped Sm2-xCexCuO4-d (x = 0.18) systems which display the so-called double resistive superconducting transition. We have performed several transport measurements in these compounds including temperature and magnetic field dependence of the electrical resistance, R(T,H), and I-V characteristics. Several aspects of the I-V characteristics were quantitatively well described by the RSJ model. The combined results strongly suggest that dissipation in granular superconducting samples is a natural consequence of the normal current flowing in parallel with the supercurrent current. 
M. S. da Luz, C. A. M. dos Santos, M. J. R. Sandim, and A. J. S.   Machado (Departamento de Engenharia de Materiais, Faenqui...