1. Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
2. Department of Mechanical Engineering, Universidad del Norte, Barranquilla, Colombia
3. Department of Mathematical Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
4. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park Pennsylvania 16802, United States