Lead substitution effects on the hysteresis curves and magnetic irreversibility lines 2212 compounds

Abstract We discuss the nature of the magnetic irreversibility line for the Bi:2212 compounds with two different lead contents. A crossover is observed in both cases at two different temperatures. This cross-over is consistent with the dimensional change of the vortex ensemble predicted by Glazman and Koshelev. This last approach provides two values of the anisotropy ratio in full agreement with the anisotropy decrease by Lead. At the crossing of the IL, no rough change of the magnetization relaxation regime is observed.