1. College of Mechanical Engineering, College of Mathematics and Physics, Sino-German Institute of Technology, Qingdao University of Science and Technology, Qingdao, Shandong, P. R. China
2. Research and Development Center for Functional Crystals, Institute of Physics, Chinese Academy of Sciences, Beijing, P. R. China
3. College of Electronic and Information Engineering, Shandong University of Science of Technology, Qingdao, Shandong, P. R. China