1. College of Physics and Center for Marine Observation and Communications, Qingdao University, Qingdao 266071, China.
2. State Key Laboratory of Electrical Insulation and Power Equipment and Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China.
3. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.
4. School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan 250100, China.
5. National Laboratory of Solid State Microstructures, Department of Materials Science and Engineering, Jiangsu Key Laboratory of Artificial Functional Materials and Collaborative Innovation Center for Advanced Materials, Nanjing University, Nanjing 210093, China.