1. State Key Laboratory
of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, P. R. China
2. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
3. King Abdullah University of Science and Technology, Division of Physical Science
and Engineering and Core Laboratories, Thuwal 23955-6900, Kingdom of Saudi Arabia
4. Key Lab of Nanodevices and Applications,
Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123, P. R. China