Oscillatory magnetic relaxation in Bi2Sr2CaCu2O8+δ

Time-resolved magneto optical measurements in Bi2Sr2CaCu2O8+δ show oscillatory relaxation of the local magnetization. The oscillatory behaviour is observed in a limited range of temperatures and fields below the vortex order-disorder phase transition line. We ascribe this phenomenon to coupled effects of thermally activated flux creep and annealing of transient disordered vortex states injected into the sample during field increase.