1. Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China
2. Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
3. Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
4. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
5. Institute of Advanced Materials, Beijing Normal University, Beijing 100875, China
6. Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, 9 Lixin road, Linan, Hangzhou 311300, Zhejiang Province, China
7. York-Nanjing Joint Centre for Spintronics and NanoEngineering, Departments of Electronics, The University of York, York YO10 5DD, United Kingdom