A Reproducible Approach of Preparing High-Quality Overdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ Single Crystals by Oxygen Annealing and Quenching Method
Yu-Xiao Zhang1, Lin Zhao1**, Gen-Da Gu2, Xing-Jiang Zhou1,3**
1National Lab for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA 3Collaborative Innovation Center of Quantum Matter, Beijing 100871
Abstract：We report a reproducible approach in preparing high-quality overdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (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 $T_{\rm c}\sim$63 K, the annealed Bi2212 begins to decompose. This accounts for the existence of the hole-doping limit and thus the $T_{\rm c}$ limit 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.
2016, Vol. 33 
