Graphene on Ru(0001): A corrugated and chiral structure

TL;DR

This study reveals that graphene on Ru(0001) forms a corrugated, reconstructed, and chiral structure with specific atomic displacements, providing detailed insights into its surface morphology and bonding characteristics.

Contribution

The paper provides a detailed structural analysis of graphene on Ru(0001), highlighting substrate reconstruction, corrugation, and induced chirality using surface x-ray diffraction.

Findings

Graphene and Ru layers are significantly corrugated.

Substrate reconstruction is induced by strong graphene bonding.

The system exhibits in-plane chirality with small rotational deviations.

Abstract

We present a structural analysis of the graphene/Ru(0001) system obtained by surface x-ray diffraction. The data were fit using Fourier-series expanded displacement fields from an ideal bulk structure, plus the application of symmetry constraints. The shape of the observed superstructure rods proves a reconstruction of the substrate, induced by strong bonding of graphene to ruthenium. Both the graphene layer and the underlying substrate are corrugated, with peak-to-peak heights of (0.82 +/- 0.15) A and (0.19 +/- 0.02) A for the graphene and topmost Ru-atomic layer, respectively. The Ru-corrugation decays slowly over several monolayers into the bulk. The system also exhibits chirality, whereby in-plane rotations of up to 2.0 degrees in those regions of the superstructure where the graphene is weakly bound are driven by elastic energy minimization.