Kinetics of the superconducting transition

The time evolution of a superconductor, following a quench from the normal state, in two dimensions is studied. For a type-I superconductor, quenched into a region where the normal state is metastable, the normal- superconductor phase boundary exhibits a dynamical instability similar to, but not identical with, that observed in solidification. In the case of a quench into the Meissner phase of a type-II superconductor, the average vortex spacing d as a function of time t is found to exhibit a crossover from d about sq rt t to d about lnt, the crossover time being an increasing function of the Ginzburg-Landau parameter. (Author)