1. School of Physics, State Key Laboratory of Crystal Materials, Shandong University, 27 Shan Da Nan Lu, Jinan 250100, China
2. Key Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
3. Department of Physics, Center for Ion Beam Application and Center for Electron Microscopy, Wuhan University, Wuhan 430072, China
4. Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, Dresden 01328, Germany