Insulating state of granular superconductors in a strong-coupling regime

We analyze the possibility of the formation of a magnetic-field-induced insulating state in a two-dimensional granular superconductor with relatively strong intergranular coupling and show that such a state appears in a model with spatial variations of the single-grain critical magnetic field. This model describes realistic granular samples with a dispersion in grain sizes and explains the mechanism leading to a giant peak in the magnetoresistance.