1. School of Materials Science and Engineering Peking University Beijing 100871 China
2. MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin Heilongjiang 150001 China
3. School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China
4. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China
5. Department of Physics and Astronomy California State University Northridge Northridge CA 91330 USA
6. BIC-ESAT College of Engineering Peking University Beijing 100871 China