1. Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
2. Department of Electronic Engineering, Royal Holloway University of London Egham, Egham, Surrey TW20 0EX, United Kingdom
3. York-Nanjing Joint Centre (YNJC) for Spintronics and Nano Engineering, Department of Electronic Engineering, The University of York, York YO10 3DD, United Kingdom
4. School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
5. Zhejiang Hikstor Technology Company, Hangzhou 311305, China