1. Department of Physics, University of Maryland, Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, Maryland 20912, United States
2. Nanoscale Device Characterization Division and Joint Quantum Institute, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
3. Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
4. Institute of Advanced Studies (IAS), College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, Hubei, China