1. Collaborative Innovation
Center of Advanced Microstructures, National Laboratory of Solid State
Microstructures and Key Laboratory of Modern Acoustics, MOE, Institute
of Acoustics, Nanjing University, Nanjing 210093, China
2. Department of Physics and Department of
Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 210093, China