Energetics of Co adatoms on the Cu(001) surface

By using an N-body potential scheme constructed by fitting the interaction parameters to accurate first-principles calculations, we investigate the st ructural stability of Co atoms and clusters deposited on Cu(100). We found that Co atoms and clusters prefer to be embedded inside the substrate, in a way compatible with the formation of a surface alloy observed experimental ly. Enhanced stability is achieved when Co atoms are deposited on a preform ed Co cluster embedded on the uppermost layer of the substrate. Co atoms de posited on Co islands are best stabilized when they concur to complete the islands, by promoting layer-by-layer growth.