1. a College of Materials, and Fujian Key Laboratory of Plasma and Magnetic Resonance, Xiamen University , Xiamen 361005, China
2. b Department of Physics, Fujian Key Laboratory of Plasma and Magnetic Resonance , State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University , Xiamen 361005, China
3. c National High Magnetic Field Laboratory, Center for Interdisciplinary Magnetic Resonance, 1800 East Paul Dirac Drive , Tallahassee, FL 32310, USA