Strain-Driven Moiré Superstructures of Epitaxial Graphene on Transition Metal Surfaces

A simple model to explain graphene Moirés on single crystal metal surfaces

Graphene revealed to be the most outstanding material of the decade. Scanning Tunneling Microscope (STM) images have proved the existence of Moiré superstructures on epitaxial graphene due to the spatial coincidence of the atomic periodicity of the graphene lattice with that of the supporting metal. Formation of Moiré superstructures has been reported on many metals, e.g. Ru, Ir , Rh , Pt , and recently Cu , Pd , Co and Ni . Surprisingly, albeit the huge, recent and still increasing number of papers devoted to this topic, the most fundamental questions about the formation, structure and stability of these Moirés have not been deeply addressed and is still a matter of scientific dispute.

We have addressed this topic by combining a geometrical model with STM images of multidomain epitaxial graphene on Pt(111). Our model predicts the formation of 22 stable superstructures for Pt(111). We have experimentally found 19 of them, which are all predicted by the model. Moreover, by applying this method to published data we can reproduce the Moiré superstructures found for other single crystal metal surfaces and we foresee the existence of other periodicities, which have not been reported yet.

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