1. Department of Physics, Southeast University, Nanjing 211189, China
2. School of Biological Sciences & Medical Engineering, Southeast University, Nanjing 210096, China
3. Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
4. NanoElectronics Group, MESA+ Institute
for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
5. Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom