1. Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
2. Department of Geological Sciences, Stanford University, Stanford, California 94305, United States
3. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
5. School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
6. Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
7. Department of Physics, Stanford University, Stanford, California 94305, United States
8. Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States