1. Department of Physics, University of Science and Technology of China, Hefei 230026, PR China
2. Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, China
3. Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, No. 96 Jinzhai Road, Hefei, Anhui 230026, China