Surface instabilities and vortex transport in current-carrying superconductors

We investigate the stability of the vortex configuration in thin superconducting films and layered Josephson-coupled superconductors under an applied current analytically and by numerical simulations of the time-dependent Ginzburg-Landau equation. We show that the stationary vortex lattice becomes unstable with re spect to long-wavelength perturbations above some critical current I-c. We find that at currents slightly exceeding I-c the vortex phase develops plastic flow, where large coherent pieces of the lattice are separated by Lines of defects and slide with respect to each other. At elevated currents a transition to elastic flow is observed. We obtained the effective one-dimensional Ginzburg-Landau equation for a description of the vortex penetration from the edges. We discuss this transition in terms of a one-dimensional phase-slip phenomenon in superconducting wires with a periodically modulated temperature. We found several distinct dynamic vortex phases in the layered current-carrying superconductors. We show that for some intermediate range of the current, depending on the coupling between the layers, the coherent motion of the pancake vortices in different layers becomes unstable leading to dynamic decoupling.