Resistivity of high-Tc superconductors in a vortex-liquid state

The theory of pinning of a vortex liquid by weak disorder is developed. Two different vortex-liquid dissipative regimes are shown to exist: the flux flow above some crossover temperature Tk, where the vortex liquid is unpinned, and the thermally assisted flux flow below Tk. The activation barriers in the latter regime are those associated with the plastic motion of the vortices in the liquid