1. School of Physics and Mechanical and Electrical Engineering Hubei University of Education Wuhan 430205 P. R. China
2. State Key Laboratory of Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China
3. Material Science and Engineering Program and Texas Center for Superconductivity at University of Houston (TcSUH) University of Houston TX 77204 USA
4. School of Electronic Electrical and Communication Engineering University of Chinese Academy of Sciences Beijing 100049 P. R. China
5. Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou 310024 P. R. China
6. Engineering Research Center of Nano‐Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry China University of Geosciences Wuhan 430074 P. R. China