1. Institute of Nanoscience and Nanotechnology, College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
2. Department of Physics and Texas Center for Superconductivity at the University of Houston (TcSUH), University of Houston, Houston, Texas 77204, United States
3. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China