DYNAMICS OF THE 2ND PEAK IN THE MAGNETIZATION OF BI2SR2CACU2O8 CRYSTALS

We use a combination of relaxation measurements and magnetic hysteresi s loops at different field ramp rates to explore the dynamical behavio r of the second peak in the magnetization of Bi2Sr2CaCu2O8 crystals. W e find that the second peak is absent in the short-time limit. It evol ves at intermediate time scales due to a different decay rate of the B ean profile at fields above and below the second peak. At long time sc ales, when the Bean profile for fields below the second peak has decay ed, the size of the second peak saturates. Finally, while the Bean pro file above the second peak field slowly decays, the second peak decrea ses and vanishes.