1. Ministry of Education Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Provincial Key Laboratory of Polymers School of Materials Science and Engineering Hubei University Wuhan 430062 P. R. China
2. Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan 430071 P. R. China
3. Department of Physics and Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education Wuhan University Wuhan 430072 China
4. Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology Beijing 100022 P. R. China
5. Physics Department Oakland University Rochester MI 48309 USA