1. School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
2. University of Chinese Academy of Sciences, Beijing 100190, China
3. Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
4. School of Physics and Electronics, Hunan University, Changsha 410082, China
5. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
6. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan