1. National Laboratory of Solid State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China
2. Beijing Key Laboratory of Optoelectronic Functional Materials & Micro‐Nano Devices Department of Physics Renmin University of China Beijing 100872 P. R. China
3. Center for Quantum Materials Synthesis, and Department of Physics and Astronomy, Rutgers The State University of New Jersey Piscataway NJ 08854 USA