1. Key Laboratory of Magnetic Materials and Devices; Ningbo Institute of Material Technology & Engineering; Chinese Academy of Sciences; Ningbo 315201 China
2. Department of Physics; University of Texas at Arlington; Arlington TX 76019 USA
3. College of Sciences; Northeastern University; Shenyang 110819 China
4. Shenyang National Laboratory for Materials Science; Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110011 China