SKM 2023 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 1: 2D Materials and their Heterostructures I: Graphene

DS 1.5: Vortrag

Montag, 27. März 2023, 10:30–10:45, SCH A 316

Twist angle dependent proximity induced spin-orbit-coupling in graphene/TMDC and graphene/TI heterostructures — •Thomas Naimer¹, Klaus Zollner¹, Martin Gmitra², and Jaroslav Fabian¹ — ¹Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany — ²Institute of Physics, Pavol Jozef Safarik University in Kosice, 04001 Kosice, Slovakia

We investigate the proximity-induced spin-orbit coupling in twisted heterostructures of graphene/transition-metal dichalcogenides (MoS₂, WS₂, MoSe₂, and WSe₂) as well as graphene/topological insulators (Bi₂Se₃ and Bi₂Te₃) from first principles. We establish that, regardless of the twist angle, the band offsets between the Dirac point and the substrate bands vary linearly with the strain, which is necessary for defining commensurate supercells. This relation allows to identify the apparent zero-strain band offsets and find a compensating transverse electric field correcting for the strain. The resulting corrected band structure is then fitted around the Dirac point to an established spin-orbit Hamiltonian, yielding the twist angle dependencies of the spin-orbit couplings. While for most structures a mix of Rashba and valley-Zeeman spin-orbit coupling is present, we also witness the emergence of Kane-Mele spin-orbit coupling in graphene/topological insulator structures at 30^∘ twist angle. This work was funded by the Elite Network of Bavaria, the Deutsche Forschungsgemeinschaft (DFG), SFB 1277, SPP 2244 and by the European Union Horizon 2020 Research and Innovation Program under contract number 881603 (Graphene Flagship). M.G. acknowledges VEGA 1/0105/20.