1. Institute of PhysicsNational Laboratory for Condensed Matter PhysicsChinese Academy of Sciences Beijing 100190 China
2. School of Physical SciencesUniversity of Chinese Academy of Sciences Beijing 100190 China
3. High Magnetic Field LaboratoryChinese Academy of Sciences Hefei Anhui 230031 China
4. Institute of Electrical EngineeringChinese Academy of Sciences Beijing 100190 China
5. Shanghai Synchrotron Radiation FacilitiesShanghai Institute of Applied PhysicsChinese Academy of Sciences Shanghai 201204 China
6. Department of ChemistryPrinceton University Princeton NJ 08544 USA
7. Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China