The irreversibility lineHirr(T) and reversible magnetizationM(H) for magnetic field applied along thea-axis of Bi2Sr2CaCu2O8+δ were determined in the vicinity ofTc. TheHirr(T) was found to be located at higher fields than those predicted by an anisotropic vortex-lattice melting scaling approach. Obtained results can be explained by the discrepancy between the fields of the appearance of the irreversibilityHirr and those of the vortex-lattice melting and/or by higher value of the effective mass anisotropy than the values commonly accepted for the Bi2Sr2CaCu2O8+δ.
R. Puźniak, K. Nakao, G. Gu
Czechoslovak Journal of Physics