Monte Carlo studies of the ordering of ceramic superconductors: Chiral-glass, orbital-glass, and nonlinear susceptibilities

Static and dynamic properties of the intergranular ordering of ceramic superconductors are studied by Monte Carlo simulations on a three-dimensional lattice model of a Josephson-junction array with finite self-inductance. Both cases of d-wave and s-wave pairing symmetries are studied. In the case of d-wave ceramics, intrinsic frustration effects combined with quenched randomness lead to the glassy behavior reminiscent of the spin glass even in zero magnetic field. It is found that the zero-field nonlinear susceptibility exhibits a negatively divergent behavior, suggesting the occurrence of a cooperative transition into an ordered state characterized by the random freezing of chirality or flux. In this ''chiral-glass'' state, global Z(2) time-reversal symmetry appears to be broken spontaneously with keeping the U(1) gauge symmetry. Dynamic simulations on the linear ac susceptibility suggest that d-wave ceramics exhibits much stronger dissipation than s-wave ceramics in the low-frequency regime. In the case of s-wave ceramics, standard; superconducting transitions with broken U(1) gauge symmetry occurs where nonlinear susceptibility exhibits only a very weak anomaly. Implications to experiments on high-T-c ceramics are discussed.