Off-equilibrium properties of vortex creep in superconductors

We study a model for the dynamics of vortices in type-II superconductors. In particular, we discuss glassy ''off-equilibrium'' properties and ''aging'' in magnetic creep. At low temperatures a crossover point is found, Tg, where relaxation times seem to diverge a la Vogel-Tamman-Fulcher. Magnetic creep changes by crossing Tg: above Tg power law creep is found asymptotically followed by stretched exponential saturation; below Tg the creep is logarithmic and vortex motion strongly subdiffusive. In this region violation of time translation invariance is found along with important dynamical scaling properties. (orig.)