1. School of Advanced Materials Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
2. X‐ray Science Division Advanced Photon Source Argonne National Laboratory Lemont IL 60439 USA
3. Department of Physics Southern University of Science and Technology Shenzhen 518055 P. R. China
4. State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China