1. School of Physics and Electronic Science, Zunyi Normal University, Zunyi 563006, China
2. Department of Physics, Zhejiang Normal University, Jinhua 321004, China
3. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China
4. School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China