1. Guangxi Key Laboratory of Information MaterialGuangxi Collaborative Innovation Center of Structure and Property for New Energy and MaterialsSchool of Material Science and EngineeringGuilin University of Electronic Technology Guilin 541004 P. R. China
2. International Research Center for Nuclear Materials ScienceInstitute for Materials ResearchTohoku University Oarai Ibaraki 311‐1313 Japan
3. National Laboratory of Solid State MicrostructuresCollege of Engineering and Applied SciencesSchool of Physics, and Collaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210093 P. R. China