1. Department of Physics, South China University of Technology, Guangzhou 510640, China
2. Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
3. Quanzhou Institute of Equipment Manufacturing, Haixi Institute, Chinese Academy of Sciences, Quanzhou 362200, China
4. School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia