TEMPERATURE-DEPENDENCE OF THE MAGNETIZATION OF A BI2SR2CACU2O8+DELTA SINGLE-CRYSTAL CLOSE TO T(C)

The magnetization M(T,H) of a Bi2Sr2CaCu2O8+delta single crystal has been measured above and below the superconducting transition temperature in externally applied magnetic fields H up to 50 kOe for H parallel-to c. We find that M(T,H) is independent of H at a particular temperature T* for external fields exceeding 10 Oe, and exhibits a two-dimensional (2D) scaling behavior as a function of [T - T(c)(H)]/(HT)1/2. The parameters xi(ab)(0) almost-equal-to 21.4 angstrom and xi(c)(0) almost-equal-to 0.4 angstrom are estimated from fitting the experimental data to a full Lawrence-Doniach model calculation of the fluctuation-induced magnetic susceptibility. From the same analysis, we obtain dH(c2)/dT almost-equal-to -14 kOe/K in the range 5 kOe < H < 50 kOe.