Interface-state properties for strained-layer Ni adsorbed on Ru(0001)

Publisher Website
Google Scholar
Abstract
Studies of ultrathin layers of Ni on Ru(0001) by He i photoemission and theoretical calculations reveal the existence of surface and interface states resulting from the Ni(3d)-Ru(4d) interaction. Pure Ni surface states are found centered at a binding energy of about -1.4 eV. Split about this position are two pairs of Ni-Ru states of different symmetry character. The highest lying of these states is identified as an interface state of mostly Ni character and dσ symmetry, while the most tightly bound ones are identified as mostly Ru in character and of dσ symmetry. The splitting between these interface states is 3.1 eV, reflecting a combination of the d-band offset of Ni relative to Ru and the level repulsion engendered by the Ni-Ru interaction. A similar combination of states with mixed dπ-dδ symmetry is found having a splitting of about 2.7 eV. Analogous states are found for the Cu/Ru(0001) bimetallic system. The two systems differ principally due to the relative positions of the d states for Cu (deeper) compared to Ni.