1. Wuhan National High Magnetic Field Center School of Physics Huazhong University of Science and Technology Wuhan Hubei 430074 P. R. China
2. Wuhan National Laboratory of Optoelectronics Huazhong University of Science and Technology Wuhan Hubei 430074 P. R. China
3. State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan Hubei 430074 P. R. China
4. Department of Materials Science and Engineering University of Tennessee Knoxville TN 37996 USA
5. Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of Science Hefei Anhui 230031 P. R. China