1. Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
2. College of Physical Science and Technology, Sichuan University, Chengdu 610064, People’s Republic of China
3. Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CAS), Changchun 130033, People’s Republic of China
4. School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, New South Wales 2052, Australia
5. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, 22 Hankou Road, Nanjing 210093, People’s Republic of China