1. Department of Electrical Engineering, University of California, Los Angeles, California 90095,
United States
2. Department of Physics, California Institute of Technology, Pasadena, California
91125, United States
3. Center
of Electron Microscopy,
State Key Laboratory of Silicon Materials, Department of Materials
Science and Engineering, Zhejiang University, Hangzhou, 310027, China
4. Department
of Physics, University of California, Berkeley,
California 94720,
United States
5. Materials Sciences
Division, Lawrence Berkeley National Laboratory, Berkeley, California
94720, United States
6. National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United
States