Voltage induced electrical connectivity on a percolation cluster

Considering the very recent interest in the flow between two sites on a percolation cluster it is obvious that an experimental study of such a problem requires local measurement techniques. Following this observation we report the first study of the voltage dependence of the images derived by contact-resistance atomic force microscopy (C-AFM) in general, and on a binary composite in particular. The results obtained provide an experimental map of the voltage dependence of the realized connectivity between a given pair of sites on a percolation cluster. Our measurements show that the two-dimensional cross-section images of a three-dimensional percolation cluster reveal a systematic behavior that can be described as a phase transition.