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O: Fachverband Oberflächenphysik

O 92: Nanostructures at Surfaces II

O 92.10: Vortrag

Donnerstag, 21. März 2024, 17:15–17:30, MA 042

Revisiting the realization of artificial graphene by fullerenes on gold and copper surfaces — •Dmitry Marchenko¹, Maxim Krivenkov¹, Maryam Sajedi¹, Alexander Fedorov^1,2, Jaime Sánchez-Barriga¹, Oliver Clark¹, Emile Rienks¹, Oliver Rader¹, and Andrei Varykhalov¹ — ¹Helmholtz-Zentrum Berlin für Materialien und Energie — ²IFW Dresden

There has been significant progress in the creation of artificial graphene based on molecular networks. For a layer of C60 molecules on Au(111) and Cu(111) surfaces, graphene-like Dirac cones were reported by angle-resolved photoelectron spectroscopy (ARPES). The explanation given is based on a hexagonal network of hollow sites in the 2D surface electron gas, due to the expulsion potential of adsorbed molecules, with the corresponding formation of an electronic honeycomb structure.

Using ARPES and DFT methods we demonstrate [1,2] that the observed bands are neither Dirac cones nor hybridization states. They are formed by final state photoelectron diffraction on a regularly arranged C60 molecular layer. This effect creates a highly coherent pattern of replicated bands, which mimics Dirac cones.

In addition, we discuss in detail the nature of well-known steeply dispersing states in the Au(111) and Cu(111) electronic structure. Traditionally these states are believed to be bulk sp-bands, but we demonstrate that they are a manifold of 2D surface resonance bands leaking into the bulk.

[1] M. Krivenkov et. al., Nanoscale 14, 9124 (2022).

[2] D. Marchenko et. al., Phys. Rev. B 108, 115155 (2023).

Keywords: artificial graphene; fullerenes; graphene; 2D; Dirac cone