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O: Fachverband Oberflächenphysik

O 45: Graphene: Adsorption, Intercalation and Doping

O 45.5: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Superstructures and Phonons of Graphene on Ir(111) Induced by Li Intercalation — •Johannes Halle, Nicolas Néel, and Jörg Kröger — Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany

Lithium-intercalated graphene on Ir(111) exhibits various superstructures with increasing coverages as unveiled with low-temperature scanning tunnelling microscopy. At low coverages Li always resides at one specific high-symmetry site of the moiré pattern. Compact, elongated and trefoil-like Li clusters become the building blocks of superstructures at higher coverages. Their shapes and orientations reflect local strain variations in the graphene sheet and the energy landscape of different sites in the moiré unit cell. Intercalation of Li enables the observation of graphene phonons in inelastic electron tunnelling spectroscopy. While for pristine graphene phonon features stay below the detection limit, clear signatures of Μ point acoustic and optical phonons appear in the spectra of Li-intercalated graphene.

Funding by the Deutsche Forschungsgemeinschaft through KR 2912/10-1 is acknowledged.