Oscillating flux instability in vortex matter

We explain theoretically an oscillatory behaviour in space and time of the magnetic induction in Bi2Sr2CaCu2O8+delta crystals during magnetic relaxation. This new "flux waves" phenomenon appears near the order-disorder vortex phase transition, under specific conditions of temperature and induction gradient. Our theory is based on two coupled equations: The Landau-Ginzburg equation for the order parameter of the vortex phase transition and the diffusion equation for the magnetic induction. Linear stability analysis of these equations shows an appearance of oscillatory instabilities characterized by a period and wavelength that are in accordance with the experimental results. (c) 2007 Elsevier B.V. All rights reserved.