1. School of Physics, Beijing Institute of Technology, 100081 Beijing, People’s Republic of China
2. Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, People’s Republic of China
3. University of Chinese Academy of Sciences, 100049 Beijing, People’s Republic of China
4. Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
5. Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, 100081 Beijing, People’s Republic of China
6. Department of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany