DYNAMICAL EXPONENTS FOR THE CURRENT-INDUCED PERCOLATION TRANSITION INHIGH-T-C SUPERCONDUCTORS

A detailed study of dissipation in weak link networks of high-T-c supe rconductors has been performed. The model for dissipation has been ela borated assuming a general correspondence with the problems of inhomog enous charge transport. The model treats the basic experimental ingred ients, current-voltage (I-V) and current-differential resistance (I-dV /dI) characteristics, as a current-induced critical phenomenon. The va lidity of a simple relationship between non-Ohmic weak link network an d Ohmic classical percolation networks has been proved; allowing a qua ntitative interpretation of I-V characteristics. These characteristics are primary determined by dynamical features of transport on percolat ion networks. The model focuses on both aspects of of the scaling-rela ted power law, its dynamical exponent and its prefactor, and gives spe cific predictions for magnetic field and temperature dependencies, The experimental results are in full agreement with both predictions. In particular, the experimental values of dynamical scaling exponents (t = 2, s = 0.7) coincide with generally accepted literature values for t hree-dimensional systems.