1. Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart MaterialsChongqing University Chongqing 401331 P. R. China
2. Department of Physics and AstronomyClemson University Clemson SC 29634 USA
3. Chongqing Institute of Green and Intelligent TechnologyChinese Academy of Science Chongqing 400714 P. R. China
4. Department of Materials Science and EngineeringNorthwestern University Evanston IL 60208 USA
5. Department of PhysicsChun Yuan Christian University Chung‐Li District Taoyuan City 32023 Taiwan
6. Department of Materials and EngineeringClemson University Clemson SC 29634 USA
7. Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education)Superconductivity and New Energy R&D CenterSouthwest Jiaotong University Chengdu 610031 China
8. University of Chinese Academy of Sciences Beijing 100044 P. R. China