1. Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
2. Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
3. Dept. Materials Science and Engineering, The University of Texas at Dallas, Dallas, Texas 75080 United States
4. Dept. Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 United States
5. Dept. Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802 United States