1. Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, P. R. China
2. Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory (HMFL), Chinese Academy of Sciences, Hefei 230031, P. R. China
3. Chemical Engineering, University of South Carolina, 301 S. Main Street, Columbia, South Carolina 29208, United States