1. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 P. R. China
2. Department of Physics & Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Spallation Neutron Source Science Center Dongguan 523803 P. R. China
4. Department of Physics Saint Joseph's University Philadelphia PA 19131 USA
5. Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA
6. Songshan Lake Materials Laboratory Dongguan Guangdong 523808 P. R. China
7. Key Laboratory of Material Physics & School of Physics and Microelectronics Zhengzhou University Zhengzhou 450001 P. R. China
8. National Center for Electron Microscopy in Beijing and School of Materials Science and Engineering Tsinghua University Beijing 100084 P. R. China
9. Department of Physics and Astronomy University of Tennessee Knoxville TN 37996 USA
10. Department of Physics Southern University of Science and Technology Shenzhen 518055 P. R. China