STRONGLY NONLINEAR RESPONSE OF FRACTAL CLUSTERS

We have developed a differential effective medium approximation (DEMA) for the effective nonlinear response due to clustering of a strongly nonlinear conducting material of a current-field (J-E) response of the form J = chi\E\(2 beta)E (beta > 0) in a host medium, where chi is th e nonlinear coefficierit. The DEMA results are compared with numerical calculations in a deterministic fractal model. As a similar problem o f a random medium, we further investigate the scaling behavior of the nonlinear response. It is shown that by choosing a relevant scaling va riable properly, the nonlinear response function can be rescaled to co llapse onto a universal curve;