First principles theory of artificial metal chains on NiAl(110) surface

Using first-principle calculations we have studied the stable phases of metal-atom chains on the (110) surface of NiAl. Our investigation is mainly focused on the technologically relevant case of Au chains, but the results will be analyzed in the broader framework of a family of metallic systems. We demonstrate that the nature of the adatom (Au, Mn, Ni, Cu, Al, H, C, Na, K, and Ca) is responsible for different levels of interaction with the substrate and gives rise to a variety of electronic behaviors. With some transition metals (such as Au, Mn, Ni, and Cu) the NiAl surface acts as a simple structural template for the formation of the artificial one-dimensional system and does not affect the electronic properties of the chains. With other atomic species (H, C, Na, K, and Ca) we observe substantially different couplings and stronger interactions. We demonstrate that the different electronic properties of the various adatoms are responsible for different couplings with the substrate and compare our findings with the existing experimental results. Finally, in the case of Au chains we have investigated the role of adatom-adatom interactions in the formation of such one-dimensional structures.