1. CAS Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 P. R. China
2. Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 P. R. China
3. University of Chinese Academy of Sciences Beijing 100049 P. R. China
4. School of Material Chemistry Ningbo University Ningbo Zhejiang 315201 P. R. China
5. National Institute for Materials Science 1‐1 Namiki Tsukuba Ibaraki 305‐0044 Japan
6. Helmholtz‐Zentrum Dresden‐Rossendorf e.V Institute of Ion Beam Physics and Materials Research Bautzner Landstrasse 400 01328 Dresden Germany