LOCAL MAGNETIC-RELAXATION CLOSE TO THE 2ND PEAK IN BSCCO CRYSTALS

Local magnetic relaxation measurements were performed on Bi2Sr2CaCu2O8 +x (BSCCO) single crystals using a Hall-sensor array. The recorded fie ld profiles provide unambiguous evidence of a crossover from surface b arrier to bulk pinning in the second magnetization peak region. Both c ontributions to the magnetization exhibit a pronounced relaxation. For fields above the second peak we observe an additional crossover from bulk-pinning at short time scales, with Bean-like profiles, to dome-sh ape profiles originating from surface barrier at long times.