1. Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR 999077, P. R. China
2. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
3. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China
4. Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 999077, P. R. China