Silicene on Monolayer PtSe: From Strong to Weak Binding via NH Intercalation.

We study the properties of silicene on monolayer PtSe by first-principles calculations and demonstrate a much stronger interlayer interaction than previously reported for silicene on other semiconducting substrates. This fact opens the possibility of a direct growth. A band gap of 165 meV results from inversion symmetry breaking and large spin-splittings in the valence and conduction bands from proximity to monolayer PtSe and its strong spin-orbit coupling. It is also shown that the interlayer interaction can be effectively reduced by intercalating NH molecules between silicene and monolayer PtSe without inducing charge transfer or defect states near the Fermi energy. A small NH diffusion barrier makes intercalation a viable experimental approach to control the interlayer interaction.