1. Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Materials Science & Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing 100081, China
2. Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
3. Micro Nano Technology Center, School of Physics, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing 100081, China