Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 20: Topology: Poster Session
TT 20.1: Poster
Wednesday, September 7, 2022, 15:00–18:00, P1
Effects of in-plane polarised light on graphene: Band gap, spin and topological quantum numbers — •Frederik Bartelmann1, Marta Prada2, and Daniela Pfannkuche1,3 — 1University of Hamburg, I. Institute of Theoretical Physics — 2University of Hamburg, Institute of Nanostructure and Solid State Physics — 3The Hamburg Centre for Ultrafast Imaging
If it were not for the effects of spin-orbit interaction, the band gap in graphene would close at the K-points, resulting in perfect Dirac cones. In this work, a graphene tight-binding band structure involving atomic s-, p- and d-orbitals is modified by irradiation with light. The light is polarised in-plane to affect the dxz- and dyz-orbitals, which are coupled via spin-orbit interaction, and the pz-orbitals, which are predominant in the valence and conduction band. Floquet formalism is used to obtain dressed states and an altered band structure. The changes to valence and conduction band and thus the band gap are studied for a range of frequencies in the PHz regime. Along these studies, the correlation between real- and sublattice spin is probed as well as topological properties and how they behave under a change of frequency. Since the focus lies on the effects due to changes in the orbital composition of the dressed states, inter-band couplings are prioritised over intra-band ones. The goal of the studies is to gauge the effect of different irradiated frequencies on graphene and to evaluate possible applications of dressed states for topological quantum computers.