Regensburg 2022 – scientific programme

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DS: Fachverband Dünne Schichten

DS 19: 2D Materials 7 (joint session DS/CPP)

DS 19.1: Talk

Wednesday, September 7, 2022, 15:00–15:15, H17

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures — •Jonas Kiemle^1,2, Lukas Powalla^3,4, Katharina Polyudov^3,4, Lovish Gulati³, Maanwinder Singh^1,2, Alexander Holleitner^1,2, Marko Burghard^3,4, and Christoph Kastl^1,2 — ¹Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany — ²MCQST, München, Germany — ³Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — ⁴Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Van der Waals heterostructures made from graphene and three-dimensional topological insulators promise very high electron mobilities, a non-trivial spin texture and a gate-tunability of electronic properties. Here, we explore epitaxially grown interfaces between graphene and the lattice-matched topological insulator Bi₂Te₂Se. For this heterostructure, spin-orbit coupling proximity has been predicted to impart an anisotropic and electronically tunable spin texture. Polarization-resolved second-harmonic generation, Raman spectroscopy, and time-resolved magneto-optic Kerr microscopies are combined to demonstrate that the atomic interfaces align in a commensurate symmetry with characteristic interlayer vibrations. By polarization-resolved photocurrent measurements, we find a circular photogalvanic effect which is drastically enhanced at the Dirac point of the proximitized graphene. We attribute the peculiar gate-tunability to the proximity-induced interfacial spin structure.