Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 25: Focus Session: Atomic-Scale Characterization of Correlated Ground States in Epitaxial 2D Materials
O 25.3: Talk
Tuesday, September 6, 2022, 11:30–11:45, H2
Topological Surface State in epitaxial zz-GNRs — •M. Gruschwitz1, T.T.N. Nguyen1, N. de Vries2, H. Karakachian3, J. Aprojanz1, A.A. Zakharov4, C. Polley4, T. Balasubramanian4, U. Starke3, C.F.J. Flipse2, and C. Tegenkamp1 — 1Technische Universität Chemnitz, Chemnitz, Germany — 2Eindhoven University of Technology, Eindhoven, The Netherlands — 3Max Planck Institute for Solid State Research, Stuttgart, Germany — 4MAX IV Laboratory and Lund University, Lund, Sweden
Protected and spin-polarized transport channels are the hallmark of topological insulators, coming along with an intrinsic strong spin-orbit coupling. Here we identified such corresponding chiral states in epitaxially grown zigzag graphene nanoribbons (zz-GNRs) on mesa-SiC(0001) templates, albeit with an extremely weak spin-orbit interaction. While the bulk of the monolayer zz-GNR is fully suspended across a SiC facet, the lower edge merges into the SiC(0001) substrate and reveals a surface state at the Fermi energy, which is extended along the edge and splits in energy toward the bulk. All of the spectroscopic details are precisely described within a tight binding model incorporating a Haldane term and strain effects. The concomitant breaking of time-reversal symmetry without the application of external magnetic fields is supported by ballistic transport revealing a conduction of G = e2/h [1,2]. [1] J. Baringhaus et al., Nature 506, 349 (2014); [2] T.T.N. Nguyen et al. Nano Lett. 21, 2876 (2021)