1. School of Physics and Engineering, Henan University of Science and Technology, Luoyang City 471023, Henan Province, China
2. College of Chemistry, Zhengzhou University, Zhengzhou 450001, Henan Province, P. R. China
3. Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
4. International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China