PHENOMENOLOGICAL THEORY OF THE PARAMAGNETIC MEISSNER EFFECT

We study the paramagnetic Meissner effect in a network of Josephson ju nctions which include a random distribution of pi junctions. We perfor m dynamical Langevin simulations for the field cooling (FC) and zero-f ield cooling (ZFC) susceptibilities. We show that while the ZFC suscep tibility is diamagnetic and of the order of -1/4pi, the FC susceptibil ity can be paramagnetic for a finite concentration of pi junctions. Th e field and concentration dependence of the FC susceptibility is studi ed. The model presents some glassy properties and the results are in g ood qualitative agreement with recent experiments in ceramic Bi compou nds.