Probing the nature of the diamagnetic transition in Tl-based superconductors

We summarize here some of our magnetization measurements performed around Tc in Tl2Ba2Ca2Cu3O10 and Tl0.5Pb0.5Sr2CaCu2O7 single crystals with narrow Meissner transitions (which guarantees the absence of appreciable Tc inhomogeneities). The experimental data are quantitative and consistently explained in the different regions of the T-H diagram in terms of the conventional Ginzburg-Landau approaches for layered superconductors.