1. Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University 1 , Nanjing 210093, China
2. School of Integrated Circuits, Nanjing University 2 , Suzhou 215163, China
3. Department of Physics, Nanjing University 3 , Nanjing 210093, China
4. Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences 4 , Shanghai 201204, China
5. York-Nanjing International Joint Center in Spintronics, Department of Electronics and Physics, University of York 5 , York YO10 5DD, United Kingdom