1. School of Physics and Materials Science; Radiation Detection Materials & Devices Lab; Anhui University; Hefei 230039 P.R. China
2. Key Laboratory of Materials Physics; Anhui Key Laboratory of Nanomaterials and Nanostructure; Institute of Solid State Physics; Chinese Academy of Sciences; Hefei 230031 P.R. China
3. Anhui Key Laboratory for Condensed Matter Physics at Extreme Conditions; High Magnetic Field Laboratory of Chinese Academy of Science; Hefei 230031 P.R. China