CONDUCTIVITY AND 1/F-NOISE STUDY OF 3-COMPONENT RANDOM RESISTOR NETWORKS

Topological and electrical transport properties of three-component random resistor networks (RRN's) i.e., RRN's that contain three types of conductance g = 0, g = h(g) << 1, and g = 1, are investigated. Such networks confirm the universality hypothesis but show a much faster increase of conductivity above, rather than inside, the critical region. This originates from the quasibicritical topology of a percolating cluster. Besides the classical percolation threshold in which the conducting infinite cluster is cut, there is also a metallic percolation threshold in which the metallic infinite subcluster (i.e., formed only from g = 1 bonds) first appears. Another implication of the quasibicritical nature of the investigated RRN is the local peak in the S-versus-p relation, where S denotes the relative power spectrum of the 1/f noise and p is the concentration of occupied sites. The basic results obtained with the help of the node-link-blob picture of a percolation cluster were also confirmed by Monte Carlo small-cell real-space renormalization-group computations. The possibility and conditions of utilizing of three-component RRN's in the modeling of real metal-insulator composites are also discussed.