  Metal deposition on oxide surfaces usually results in adatoms, clusters, or
islands of the deposited material, where defects in the surface often act as
nucleation centers. Here an alternate configuration is reported. After the
vapor deposition of Fe on the In$_2$O$_3$(111) surface at room temperature,
ordered adatoms are observed with scanning tunneling microscopy. These are
identical to the In adatoms that form when the sample is reduced by heating in
ultrahigh vacuum. Density functional theory (DFT) calculations confirm that Fe
interchanges with In in the topmost layer, pushing the excess In atoms to the
surface where they arrange as a well-ordered adatom array.
