1. Centre for Programmable Materials; School of Materials Science and Engineering; Nanyang Technological University; Singapore 639798 Singapore
2. Materials Science and Technology Division; Oak Ridge National Lab; Oak Ridge TN 37831 USA
3. Department of Physics and Astronomy; Vanderbilt University; Nashville TN 37235 USA
4. National Institute of Advanced Industrial Science and Technology (AIST); Tsukuba 305-8565 Japan
5. Beijing National Laboratory for Condensed Matter Physics; Institute of Physics; Chinese Academy of Sciences; Beijing 100190 China
6. Division of Physics and Applied Physics; School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore
7. Department of Physics; National Tsing Hua University; Hsinchu 30013 Taiwan
8. Centre for Advanced 2D Materials and Graphene Research Centre; National University of Singapore; Singapore 117546 Singapore
9. Department of Physics; National University of Singapore; Singapore 117542 Singapore
10. Institute of Physics; Academia Sinica; Taipei 11529 Taiwan
11. Centre for Disruptive Photonic Technologies; School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore
12. Collaborative Innovation Center of Quantum Matter; Beijing 100871 China
13. Centre for Micro-/Nano-electronics (NOVITAS); School of Electrical & Electronic Engineering; Nanyang Technological University; 50 Nanyang Avenue Singapore 639798 Singapore
14. CINTRA CNRS/NTU/THALES; UMI 3288; Research Techno Plaza; 50 Nanyang Drive, Border X Block, Level 6 Singapore 637553 Singapore