Epitaxial graphene on metallic surfaces can form a variety of moiré superstructures due to interfacial lattice parameter and/or symmetry mismatch . The latter characterizes graphene on Ni(100), where the hexagonal carbon network accommodates onto a square surface lattice. The interfacial mismatch leads to moiré patterns with stripe-like or rhombic-network morphology and with periodicity depending on the relative misorientation angle between graphene and the Ni surface. Different moiré patterns are characterized by high resolution scanning tunneling microscopy (STM) images and successfully described by atomistic models which consider the geometric registry. Ab-initio density functional theory (DFT) simulations well reproduce the observed STM images and shed further light on the spatial corrugation of graphene and the interfacial interactions, indicating that, depending on the misorientation angle, graphene can be alternately physi- and chemisorbed or uniformly chemisorbed. The interaction is modulated periodically by the (sub)nanometer-sized moiré superstructures.
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