1. School of Materials Science and Engineering, Sichuan University, Chengdu 610065, People's Republic of China
2. Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive3, Singapore 117542
3. Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411
4. Key Laboratory of Advanced Special Material & Technology, Ministry of Education, Chengdu 610065, People's Republic of China