1. Institute of Theoretical Physics, Department of Physics, University of Hamburg, Jungiusstrasse 9, Hamburg 20355, Germany
2. Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, Ekaterinburg 620002, Russia
3. Institute for Molecules and Materials, Radboud University, Nijmegen 6525AJ, The Netherlands
4. School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
5. National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
6. The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, Hamburg 22761, Germany
7. Center for Free Electron Laser Science, Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
8. Chongqing 2D Materials Institute, Liangjiang New Area, Chongqing 400714, China