1. York-Nanjing Joint Center (YNJC) for Spintronics and Nano-Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
2. Department of Physics, University of York, York YO10 5DD, United Kingdom
3. Spintronics and Nanodevice Laboratory, Department of Electronic Engineering, University of York, York YO10 5DD, United Kingdom