Abstract
First-principles calculations based on density functional theory are used to explore the electronic-structure modulations in graphene on Ru(0001) by Au intercalation. We first use a lattice-matched model to demonstrate that a substantial band gap is induced in graphene by sufficiently strong A-B sublattice symmetry breaking. This band gap opening occurs even in the absence of hybridization between graphene $\ensuremath{\pi}$ states and Au states, and a strong sublattice asymmetry is established for a small separation ($d$) between the graphene and Au layer, typically, $dl3.0\phantom{\rule{0.28em}{0ex}}\AA{}$, which can actually be achieved for a low Au coverage. In realistic situations, which are mimicked using lattice-mismatched models, graphene $\ensuremath{\pi}$ states near the Dirac point easily hybridize with nearby (in energy) Au states even for a van der Waals distance, $d\ensuremath{\sim}3.4\phantom{\rule{0.28em}{0ex}}\AA{}$, and this hybridization usually dictates a band gap opening in graphene. In that case, the top parts of the intact Dirac cones survive the hybridization and are isolated to form midgap states within the hybridization gap, denying that the band gap is induced by sublattice symmetry breaking. This feature of a band gap opening is similar to that found for the so-called ``first'' graphene layer on silicon carbide (SiC) and the predicted band gap and doping level are in good agreement with the experiments for graphene/Au/Ru(0001).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.