1. Institute for Advanced Materials, Hubei Normal University, Huangshi 435002, China
2. School of Physics, Southeast University, Nanjing 211189, China
3. Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
4. Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China