1 Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2 Key Laboratory of Eco-Chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
3 Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
4 State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
Andrs Granados del guila and T. Thu Ha Do contributed equally to the work.