1. Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
2. School of Physical SciencesUniversity of Chinese Academy of Science Beijing 100049 China
3. Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
4. Songshan Lake Materials Laboratory Dongguan 523808 China