1. High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, P. R. China
2. University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
3. Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230031, P. R. China