1. CAS Center for Excellence in NanoscienceCAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 China
2. Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
3. Sino‐Danish CollegeUniversity of Chinese Academy of Science Beijing 100049 China
4. Key Laboratory of Artificial Micro‐ and Nano‐Structures of Ministry of EducationSchool of Physics and TechnologyWuhan University Wuhan 430072 China
5. Department of PhysicsHenan Normal University Xinxiang 453007 China