1. High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
2. University of Science and Technology of China, Hefei 230026, China
3. Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
4. Key Laboratory of Anhui Province for High Field Magnetic Resonance Imaging, Hefei 230031, China