Conductivity and 1/f-noise study of three-component random resistor networks.

Abstract

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=${\mathit{h}}_{\mathit{g}}$\ensuremath{\ll}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.