1. National Laboratory of Solid State Microstructures and Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing University, Nanjing 210093, P. R. China
2. School and Mathematics and Physics, Suzhou University of Science and Technology, Suzhou, 215011, P. R. China
3. School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
4. Department of Physics, National Chung Cheng University, Chiayi 62102, Taiwan
5. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
6. State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
7. National Laboratory of Solid State Microstructures and Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093, P. R. China