1. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 1219 Zhongguan West Road, Ningbo 315201, Zhejiang Province, P. R. China
2. Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
3. Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany
4. Center for Soft Condensed Matter Physics & Interdisciplinary Research, Soochow University, Suzhou 215006, P. R. China
5. Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany
6. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 19A Yuquan Rd, Shijingshan District, Beijing 100049, P. R. China