1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
2. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore117551, Singapore
3. High Field Magnet Laboratory, HFML-EMFL, Radboud University, 6525 EDNijmegen, The Netherlands
4. School of Physics, Frontiers Science Center for Mobile Information Communication and Security, Southeast University, Nanjing211189, P.R. China
5. University of Chemistry and Technology Prague, Technicka 5, Prague16628, Czech Republic
6. Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore117546, Singapore
7. State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, P.R. China
8. Frontier Science Center for Quantum Information, Beijing100084, P.R. China
9. Collaborative Innovation Center of Quantum Matter, Beijing100084, P.R. China
10. Beijing Academy of Quantum Information Sciences, Beijing100193, P.R. China