1. Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
2. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
3. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
4. Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
5. Eyring Materials Center, Arizona State University, Tempe, AZ 85287, USA.
6. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
7. Institute for Physics, Martin-Luther-University Halle-Wittenberg, Halle (Saale) 06120, Germany.
8. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.