Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 11: 2D Materials I: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)
O 11.5: Talk
Monday, March 16, 2020, 11:45–12:00, WIL C107
Sideband generation & pseudospin-flip excitations in graphene using tr-momentum microscopy — •Marius Keunecke1, David Schmitt1, Christina Möller1, Davood Momeni Pakdehi2, Hendrik Nolte1, Wiebke Bennecke1, Marie Gutberlet1, Matthijs Jansen1, Marcel Reutzel1, Klaus Pierz2, Daniel Steil1, Hans Werner Schumacher2, Sabine Steil1, and Stefan Mathias1 — 1Georg-August-Universität Göttingen. I. Physikalisches Institut, 37077 Göttingen, Germany — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
The coherent control of quantum states is a promising route towards new emerging phases in solids. One of these phases are the so called Floquet-Bloch states, created by a periodic driving laser. Other light-matter coupled states (Volkov states) arise close to the surface of a solid and are understood as a final state dressing by the laser light. In graphene, the driving by circularly polarized light is predicted to open up a bandgap at the dirac point and thus creating a Floquet topological insulator [1]. In our experiment, the electronic bandstructure of ML graphene on SiC (0001) is mapped during photo-excitation using a momentum microscope in combination with a 1 Mhz femtosecond HHG lightsource (26.6 eV). Different pump wavelengths and polarizations are used to disentangle the excited states dynamics and the sideband generation at high momenta. We will discuss the nature of the generated sidebands and the photoinduced anisotropic hot carrier distributions. [1] M. A. Sentef et al., Nat. Commun. 6, 7047 (2015)