Dy adsorption on and intercalation under graphene on 6 <i>H</i> -SiC(0001) surface from first-principles calculations

Previous experimental observations motivate clarification of configuration stabilities and kinetic processes for intercalation guest atoms into a layered van der Waals material such as graphene-SiC system. From our first-principles density functional theory (DFT) calculations, we analyze Dy adsorption graphene on 6H-SiC(0001) surface, where the system includes two single-atom-thick layers: top-layer (TLG) underling buffer-layer (BLG) above terminal Si layer. Our chemical potential analysis shows that single atom gallery between TLG BLG is more favorable than but underneath highly unfavorable. We obtain diffusion barriers \ensuremath{\sim}0.45 0.54 eV diffusing under TLG, respectively. find direct penetration from top almost inhibited below temperature \ensuremath{\sim}1400 K due to large global barrier at least \ensuremath{\sim}3.5 eV. Instead, can easily intercalate by crossing step (e.g., zigzag presaturated chain or reconstructed zz57). also perform DFT calculations different coverages demonstrate how favorability intercalation, well corresponding interlayer spacings, depend coverage. Consequently, provide general insight guidance extensively studied systems involving foreign SiC substrate.