PHENOMENOLOGICAL THEORY OF THE PARAMAGNETIC MEISSNER EFFECT

We study the paramagnetic Meissner effect in a network of Josephson junctions which include a random distribution of pi junctions. We perform dynamical Langevin simulations for the field cooling (FC) and zero-field cooling (ZFC) susceptibilities. We show that while the ZFC susceptibility is diamagnetic and of the order of -1/4pi, the FC susceptibility can be paramagnetic for a finite concentration of pi junctions. The field and concentration dependence of the FC susceptibility is studied. The model presents some glassy properties and the results are in good qualitative agreement with recent experiments in ceramic Bi compounds.