1. College of Physics Nanjing University of Aeronautics and Astronautics Nanjing 211106 P. R. China
2. Key Laboratory of Aerospace Information Materials and Physics (NUAA) MIIT Nanjing 211106 P. R. China
3. School of Physics and Electronic Engineering Xinyang Normal University Xinyang 464000 P. R. China
4. State Key Laboratory of Bioelectronics School of Biological Science and Medical Engineering Southeast University Nanjing 210096 P. R. China
5. College of Science Jiangsu University of Science and Technology Zhenjiang 212100 P. R. China
6. Peter Grünberg Research Centre Nanjing University of Posts and Telecommunications Nanjing 210003 P. R. China