By combining scanning tunneling microscopy with density functional theory it is shown that the $\mathrm{Bi}\left(111\right)$ surface provides a well-defined incorporation site in the first bilayer that traps highly coordinating atoms such as transition metals (TMs) or noble metals. All deposited atoms assume exactly the same specific sevenfold coordinated subsurface interstitial site while the surface topography remains nearly unchanged. Notably, $3d$ TMs show a barrier-free incorporation. The observed surface modification by barrier-free subsorption helps to suppress aggregation in clusters. It allows a tuning of the electronic properties not only for the pure $\mathrm{Bi}\left(111\right)$ surface, but may also be observed for topological insulators formed by substrate-stabilized Bi bilayers.

• Received 11 December 2014
• Revised 1 May 2015

DOI:https://doi.org/10.1103/PhysRevB.91.195441