Thermal fluctuations in the high-temperature superconductor CaLaBaCu3O7-delta

Magnetization measurements on a polycrystal of CaLaBaCu3O7-delta in high ma gnetic fields (20 to 50 kOe) are reported. The sample has a zero-field tran sition temperature T-c0 = 77 K and a transition width of 2.0 K. The results show large fluctuation effects, which can be explained by Ginzburg-Landau fluctuation theory for a two-dimensional system. The magnetization displays good scaling behavior as a function of [T - T-c(H)](TH)(1/2). The experime ntal data were fitted by using a theoretical model based in the lowest Land au levels approximation, showing good agreement. We also analyze fluctuatio n effects in conductivity measurements at zero magnetic field.