Critical fluctuations in the magnetization of Bi2Sr2CaCu2O8 near the Hc2(T) line

The magnetization measurements on Bi2Sr2CaCu2O8 single crystals with H parallel to the c axis are presented to show that the critical fluctuations in the magnetization near the Hc2(T) line can be well studied within the two-dimensional nonperturbative scaling theory developed by Teanović et al. By using this scaling theory and basic thermodynamic arguments, we obtained the Ginzburg-Landau parameter κ (115) and dHc2/dT (-2.7 T/K) near Tc for this material. In addition, we found that these derived parameters are in good agreement with those determined from the study of reversible magnetization in an intermediate field at low temperature.