High-field magnetization of HgBa2Ca2Cu3O8+delta: Fluctuations, scaling, and the crossing point

Fluctuation-induced diamagnetism is observed well above T-c in high-field torque magnetization measurements on the cuprate superconductor HgBa2Ca2Cu3O8 + delta. Universal scaling behavior anticipated by fluctuation theories is not observed in the high-field, high-temperature regime. A crossing point, where M reaches a field-independent value at a temperature which characterizes the interlayer separation. disappears in the fluctuation regime above similar to H-c2, suggesting that deviations from the lowest Landau level description of Ginzburg-Landau theory appear at high fields.