NUCLEATION, GROWTH AND KINETICS OF THE VORTEX PHASE IN THIN SUPERCONDUCTING STRIPS

The kinetics of normal phase nucleation and flux line condensation in type-II superconductors are investigated by a numerical and analytical study of the time-dependent Ginzburg-Landau equation. It is shown tha t spontaneous nucleation and the consequent penetration of vortices in to thin superconducting films, subjected to a magnetic held can be con sidered as a nonlinear stage of primary instability of the current-car rying superconducting state. The development of the instability leads to the formation of a chain of vortices. In the presence of high trans port current, the vortex phase nucleates in the superconducting strips in the form of macroscopic droplets having multiple topological charg e. The stability and the dynamics of the droplets are discussed It is found that pinning suppresses the droplet formation.