Figure 3: Interface geometry and Dirac-cone splitting.

(a) Results of ab initio calculations showing the 9 meV Rashba-split Dirac cone for graphene on gold monolayer in the on-top position (open circles) at the equilibrium distance of 3.3 Å. In the inset, a magnified view near the Dirac point is shown; lines depict the dispersion as predicted from the analytical model²⁰. (b) The Au monolayer is laterally moved to the graphene hollow sites and can now be pressed into the graphene to the non-equilibrium distance of 2.5 Å without breaking the Dirac cone but enhancing the spin–orbit splitting to 70 meV. (c) Improved model with the Au atoms still sitting in the graphene hollow sites but diluted to 0.25 ML Au in a p(2 × 2) geometry and at the equilibrium distance of 2.3 Å. Here a spin–orbit splitting of ~50–100 meV and intact Dirac cone are achieved. Blue and red lines at panels a–c denote spin-up and spin-down bands. Atomic structures are schematically shown at the bottom of each panel.