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Iron-phthalocyanine molecules self-assemble on the moiré pattern of graphene/Ir(111) as a flat and weakly interacting layer, as determined by core-level photoemission and absorption spectroscopy. The graphene buffer layer decouples the FePc two-dimensional structure from the underlying metal; the electronic structure of the FePc molecular macrocycles is preserved; and the Fe-L2,3 edges present narrower and slightly modified resonances at the FePc single-layer coverage with respect to a thin film. The FePc layer induces a slight electron doping to the Ir-supported graphene resulting in the Dirac cone position expected for an ideal free-standing-like graphene layer with the standard Fermi velocity. © 2012 American Chemical Society

Photoemission, from core levels and valence band, and low-energy electron diffraction (LEED) have been employed to investigate the electronic and structural properties of novel graphene-ferromagnetic (G-FM) systems,\ud obtained by intercalation of one mono-layer (1ML) and several layers (4ML) of Co on G grown on Ir(111).\ud Upon intercalation of 1ML of Co, the Co lattice is resized to match the Ir-Ir lattice parameter, resulting in a\ud mismatched G/Co/Ir(111) system. The intercalation of further Co layers leads to a relaxation of the Co lattice\ud and a progressive formation of a commensurate G layer lying on top. We show the C 1s line shape and the band\ud structure of G in the two artificial phases, mismatched and commensurate G/Co, through a comparison with the\ud electronic structure of G grown directly on a Co thick film. Our results show that while the G valence band\ud mainly reflects the hybridization with the d states of Co, regardless of the structural phase, the C 1s line shape\ud is very sensitive to the rumpling of the G layer and the coordination of carbon atoms with the underlying Co.\ud Even in the commensurate (1x1) G/Co phase, where graphene is in register with the Co film, from the angular\ud dependence of the C 1s core level we infer the presence of a double component, due to in-equivalent adsorption\ud sites of carbon sub-lattices

Topological insulators are a promising class of materials for applications in the field of spintronics. New perspectives in this field can arise from interfacing metal-organic molecules with the topological insulator spin-momentum locked surface states, which can be perturbed enhancing or suppressing spintronics-relevant properties such as spin coherence. Here we show results from an angle-resolved photemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM) study of the prototypical cobalt phthalocyanine (CoPc)/Bi2Se3 interface. We demonstrate that that the hybrid interface can act on the topological protection of the surface and bury the Dirac cone below the first quintuple layer.