Fractal dimensions and dimensional crossover in superconducting wire networks

We have fabricated Al wire networks in the form of submicron scale fractals including the Sierpinski Gasket (SG), arrays of SG's, and percolation clusters. Measurements have been made of the superconducting phase boundary, T_c(H), and the magnetoconductance above T_c. From analysis of the SG data we have determined the fracton dimension of that fractal. The gasket arrays show a crossover from fractal behavior at small length scales to two-dimensional behavior over large lengths, or, equivalently, small fields. The percolation networks are also inhomogeneous, but show no crossover. Presumably this is due to the addition of randomness and dead-end bonds in these patterns.