1. Center
for Crystal Research and Development, Technical Institute of Physics
and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
2. Key Laboratory of Functional
Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
3. University of the Chinese Academy of Sciences, Beijing 100049, China
4. Beijing
National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China