A Reproducible Approach of Preparing High-Quality Overdoped Bi2Sr2CaCu2O8+δ Single Crystals by Oxygen Annealing and Quenching Method

We report a reproducible approach in preparing high-quality overdoped Bi2Sr2CaCu2O8+δ(Bi2212) single crystals by annealing Bi2212 crystals in high oxygen pressure followed by a fast quenching.In this way,high-quality overdoped and heavily overdoped Bi2212 single crystals are obtained by controlling the annealing oxygen pressure.We find that,beyond a limit of oxygen pressure that can achieve most heavily overdoped Bi2212 with a Tc~63K,the annealed Bi2212 begins to decompose.This accounts for the existence of the hole-doping limit and thus the Tclimit in the heavily overdoped region of Bi2212 by the oxygen annealing process.These results provide a reliable way in preparing high-quality overdoped and heavily overdoped Bi2212 crystals that are important for studies of the physical properties,electronic structure and superconductivity mechanism of the cuprate superconductors.