1. School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China
2. Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
3. Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication (RIEC), Tohoku University, Sendai 980-8577, Japan
4. School of Engineering, Tohoku University, Sendai 980-8579, Japan
5. Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan