On phase diagram of granular superconductor

Abstract
In the self-consistent harmonic approximation a boundary of a superconducting state of granular superconductors is obtained. In two-dimensional samples (thin films) a superconducting-normal state transition is caused by a vortex-antivortex dissociation. In bulk superconductors the transition is accompanied by a loss of phase coherence due to phase oscillation anharmonicity. Phase diagrams are determined for both cases.