Picosecond studies of nonequilibrium flux dynamics in a superconductor

A fast magneto-optical technique is used to explore flux dynamics in the optically driven nonequilibrium state of type-I superconducting Pb films. It is found that the penetration of magnetic flux through the nonequilibrium intermediate state can be dramatically faster than through the normal metal. Studies as a function of how far the system is driven from equilibrium, and of the effect of a static applied magnetic field, indicate that the observations reflect the dynamics of normal/superconducting interfaces, and are strongly dependent on the microscopic pattern of the intermediate state. © 1992 The American Physical Society.