Resistive behavior of high-Tcsuperconductors: Influence of a distribution of activation energies

A model combining thermally activated motion of flux lines, viscous flux flow at high current density, and distribution of activation energies is shown to reproduce the characteristic features of current-voltage curves of high-${\mathit{T}}_{\mathit{c}}$ superconductors. In particular the recent data of Koch et al. and Zeldov et al. can be explained without invoking a continuous phase transition (freezing into a superconducting vortex-glass phase) or a logarithmic current dependence of the activation energy.