Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 94: Focus Session: Proximity Effects in Epitaxial Graphene I
O 94.6: Topical Talk
Donnerstag, 21. März 2024, 16:30–17:00, MA 141
Proximity spin-orbit coupling and topological interfaces in graphene / alloyed transition metal dichalcogenide heterostructures — •Stephen Power1 and Zahra Khatibi2 — 1School of Physical Sciences, Dublin City University, Ireland — 2School of Physics, Trinity College Dublin, Ireland
Spin-orbit coupling (SOC) in graphene can be enhanced by proximity effects in stacked graphene/transition metal dichalcogenide (TMDC) heterostructures. The TMDC layer composition determines the nature and strength of the resultant SOC induced in graphene.
Here, we demonstrate the evolution of the SOC in graphene with the composition of an alloyed TMDC layer (WxMo1−xSe2). Density functional theory is used to simulate systems with different compositions and distributions, and allows local and global signatures of the metal-atom alloying to be clarified. The low-energy spin and electronic behavior follow a effective medium model which depends only on the composition ratio x.
While graphene/MoSe2 has a simple band gap, valley-Zeeman-driven inverted bands are present in graphene/ WSe2. The topological state of mixed systems can thus be tuned by varying x, with band gap closure occurring at a critical value. Furthermore, heterostructures with W- and Mo-domains can host boundary states similar to those between AB- and BA-stacked domains in bilayer graphene. Finally, we trace the electronic evolution of alloyed heterostructures from homogeneous effective medium to domain-localised bands as the domain size increases.