Monte Carlo solution for a lattice of coupled superconducting grains

We have numerically simulated a Ginzburg-Landau model for a lattice of coupled superconducting grains in a nonsuperconducting matrix. The results unambiguously show the onset of a double superconducting transition when the intergrain normal-state resistance increases above $\sim \frac{\hslash }{e^2}\sim 4000$ Ω: the specific heat changes from Bardeen-Cooper-Schrieffer-like to broadened, and the temperature $T_c$ at which the resistivity vanishes becomes well separated from the single-grain transition temperature $T_{c0\mathrm{}}$.