1. College of Materials Science and Optoelectronic Technology and Chinese Academy of Sciences Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing101408, P. R. China
2. Department of Physics and Astronomy, Knox College, Galesburg, Illinois61401, United States
3. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing100049, P. R. China
4. RICMASS, Rome International Center for Materials Science Superstripes, Via dei Sabelli 119A, Rome00185, Italy
5. Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research, 1 Pesek Road, Jurong Island, Singapore627833, Singapore
6. National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing101400, P. R. China