1. Faculty of Materials, Jiangxi University of Science and Technology, Ganzhou, Jiangxi 341000, P. R. China
2. Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
3. Materials Research Program and the Texas Materials Institute, ETC9.184, The University of Texas at Austin, Austin, Texas 78712, United States