1. School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
2. Peter Grünberg Research Centre, College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
3. School of Electronics and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
4. School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China
5. State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China