Reinterpretation of the equilibrium magnetization of a Tl-based single crystal. Another phase transition in the mixed state of high-Tc superconductors?

We apply a recently developed scaling procedure for the analysis of the equilibrium magnetization M that was measured on a Tl-based single crystal and was recently reported in the literature. The results of our analysis are distinctly different from those obtained in the original publication where the Hao-Clem model served to analyze the magnetization data. We argue that the Hao-Clem model is not adequate for a quantitative description of the mixed state in high-Tc superconductors especially in high magnetic fields. The scaled equilibrium magnetization data reveal a pronounced kink in the M(H) dependence that might be indicative of a phase transition in the mixed state.