1. Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
4. Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
5. Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
6. Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States