1. Spintronics Institute, University of Jinan, Jinan 250022, China
2. School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore
3. School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
4. School of Science, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT University, Melbourne, Victoria 3001, Australia