1. Department of Physics, Faculty of Science, National University of Singapore, Singapore 117551, Singapore.
2. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.
3. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
4. Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.
5. Singapore Synchrotron Light Source (SSLS), National University of Singapore, Singapore 117603, Singapore.
6. Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Singapore 138634, Singapore.
7. Shanghai Key Laboratory of High Temperature Superconductors, Physics Department, Shanghai University, Shanghai 200444, China.