1. The Centre for Physical Experiments, University of Science and Technology of China, Hefei 230026, Anhui, China
2. Department of Physics, University of Science and Technology of China, Hefei 230026, Anhui, China
3. Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, School of Physical Sciences, University of Science and Technology of China, Hefei 230026, Anhui, China