1. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China
2. School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China
3. Laboratory for Neutron Scattering and Imaging (LNS) Paul Scherrer Institut (PSI) Forschungsstrasse 111 Villigen CH‐5232 Switzerland
4. Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
5. Max Planck Institute for Chemical Physics of Solids 01187 Dresden Germany
6. Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
7. State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China