1. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 P. R. China
2. School of Physical Sciences CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100190 P. R. China
3. Wenzhou Institute University of Chinese Academy of Sciences Wenzhou Zhejiang 325001 P. R. China
4. Songshan Lake Materials Laboratory Dongguan Guangdong 523808 P. R. China