Anisotropy-driven double corrugation: Coexistence of one- and two-dimensional wave patterns in epitaxial graphene on iridium

Tailoring the electronic properties of graphene is crucial for a variety of applications. In this study, we investigate the graphene growth on the high Miller-index, anisotropic Ir(311) surface, where it self-organizes into one-dimensional ripples accompanied by a short-wavelength, two-dimensional wave pattern that is spatially confined between them. By employing a combination of spectroscopy- and microscopy-based techniques, we show that carbon atoms on the ripples interact weakly with the substrate, whereas those in the flatter region between two ripples experience stronger interaction with iridium atoms, leading to a partial rehybridization of carbon orbitals towards sp3 character. Complementary density functional theory calculations identify at least three distinct families of non-equivalent carbon atoms within the graphene layer and reveal that atoms on ripples are subjected to compressive strain. Since both compressive strain and corrugation are key factors in influencing graphene's chemical reactivity, the coexistence of two different wave pattern on graphene/Ir(311) system points to a region-specific reactivity. This spatial modulation of properties offers exciting potential for the design of bifunctional catalysts, particularly for hydrogen storage applications and for advanced materials in spintronic.