1. Key Lab of Artificial Micro‐ and Nano‐Structures of Ministry of Education of China School of Physics and Technology Wuhan University Wuhan 430072 P. R. China
2. Wuhan University Shenzhen Research Institute Shenzhen 518055 P. R. China
3. School of Physics and Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan 430074 P. R. China
4. School of Electronic and Electrical Engineering Wuhan Textile University Wuhan 430200 P. R. China
5. College of Chemistry & Molecular Sciences Wuhan University Wuhan 430072 P. R. China