1 School of Physics and Electronics, Shandong Normal University Jinan 250014 China yzsong@sdnu.edu.cn.
2 Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing Beijing 100083 P. R. China.
3 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences Beijing 100190 P. R. China.
4 Department of Physics, Liaoning University Shenyang 110036 P. R. China jingang_wang@sau.edu.cn.