Magnetic relaxation in the vicinity of second magnetization peak in BSCCO crystals

Abstract : We have used Hall array and magneto-optic techniques for the investigation of magnetic relaxation in clean Bi2Sr2CaCu2O8 (BSCCO) crystals. The enhancement of the bulk critical current seen as a second peak in the magnetization curves is identified with the discontinuous change of the flux creep energy barrier vs. current relation. We propose a consistent interpretation of the hysteretic magnetization and its relaxation in clean BSCCO crystals, based on the presence of two distinct vortex matter phases, manifesting different electrodynamics. Special attention will be given to the motion of the interface between those phases across the sample.