1. School of Microelectronics, State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
2. Department of Physics; Southern University of Science and Technology; Shenzhen 518055 China
3. Department of Materials Science and Engineering; The Pennsylvania State University; University Park PA 16802 USA
4. Department of Physics; The Hong Kong University of Science of Technology; Clear Water Bay Hong Kong China
5. Department of Materials Science and Engineering; Southern University of Science and Technology; Shenzhen 518055 China