1. School of Mathematics and Physics, Institute of Atomic and Molecular Physics and Functional Materials, Jinggangshan University, Ji'an, Jiangxi 343009, People's Republic of China
2. MOE Key Laboratory of Advanced Micro-Structure Materials, School of Physics science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
3. School of Electrical Engineering and Information, Anhui University of Technology, Maanshan, Anhui 243002, People's Republic of China