DYNAMICS OF 2-DIMENSIONAL PANCAKE VORTICES IN LAYERED SUPERCONDUCTORS

The dynamics of two-dimensional (2D) pancake vortices in Josephson-cou pled superconducting/normal-metal multilayers is considered within the time-dependent Ginzburg-Landau theory. For temperatures close to T-c a viscous drag force acting on a moving 2D vortex is shown to depend s trongly on the conductivity of normal-metal layers. For a tilted vorte x line consisting of 2D vortices the equation of viscous motion in the presence of a transport current parallel to the layers is obtained. T he specific structure of the vortex line core leads to substantial dev iations from the Bardeen-Stephen theory. The viscosity coefficient is found to depend essentially on the angle gamma between the magnetic fi eld B and the c axis normal to the layers. For field orientations clos e to the layers the nonlinear effects in the vortex motion appear even for slowly moving vortex lines (when the in-plane transport current i s much smaller than the Ginzburg-Landau critical current). In this non linear regime the viscosity coefficient depends logarithmically on the vortex velocity V.