1. Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi’an Jiaotong University, Xi’an 710049, P.R. China
2. MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi’an Jiaotong University, Xi’an 710049, P.R. China
3. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. Department of Chemistry and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
5. Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States