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O: Fachverband Oberflächenphysik
O 28: Moire and Graphene Stacking
O 28.5: Vortrag
Dienstag, 17. März 2015, 15:00–15:15, MA 041
What are the possible moiré patterns of graphene on hexagonally packed surfaces? - Universal solution for hexagonally packed coincidence lattices, derived by a geometric construction — •Patrick Zeller1 and Sebastian Günther2 — 1Department Chemie, LMU, Butenandtstr. 5-13, D-81377 München — 2Chemie Department, TUM, Lichtenbergstr. 4, D-85748 Garching
We performed a systematic investigation of two coinciding lattices and their spatial beating frequencies that lead to the formation of moiré patterns. A mathematical model was developed and applied for the case of a hexagonally arranged adsorbate layer on a hexagonal support lattice. In particular, it describes the moiré patterns observed for graphene (g) grown on hexagonally arranged transition metal surfaces, systems that serve as promising synthesis routes for the formation of this highly wanted material. We use a geometric construction that derives analytic expressions for first and higher order beating frequencies occurring for arbitrarily oriented g on an underlying substrate lattice. By solving the corresponding equations, we can predict the size and orientation of the resulting moiré patterns. Adding the constraints for commensurability delivers further solvable analytic equations that predict, whether or not first or higher order commensurable phases occur. We explicitly treat the case for first, second and third order commensurable phases. The universality of our approach is tested by comparing our data with moiré patterns that are experimentally observed for g-Ir(111) and g-Pt(111). The derived general properties of such patterns may be used to critically discuss reported moiré unit cells.