1. Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
2. Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266000, China
3. School of Physics, Shandong University, Jinan 250100, China
4. Truth Instruments Co. Ltd., Qingdao 266000, China