1. Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, P. R. China
2. Department of Electrical and Computer Engineering, University of Houston, Houston, Texas 77204, United States
3. College of Electronics & Information Engineering, Sichuan University, Chengdu, Sichuan 610064, P. R. China
4. Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, United States
5. Department of Mechanical Engineering, University of Houston, Houston, Texas 77204, United States
6. School of Materials Science and Engineering, Yunnan University, Kunming, Yunnan 650091, P. R. China
7. Department of Physics, University of Houston, Houston, Texas 77204, United States
8. Materials Science & Engineering, University of Houston, Houston, Texas 77204, United States
9. Ingram School of Engineering, Texas State University, San Marcos, Texas 78666, United States