Surface states on NiAl(110)

Abstract

Surface states on NiAl(110) have been investigated experimentally using angle-resolved photoemission and theoretically with a self-consistent pseudopotential scheme within the local-density approximation (LDA). Both theory and experiment show that the termination of bulk NiAl at the (110) surface creates surface states in the gap regions of the projection of the bulk bands and strong d resonance states around the gap edges. In general, the energy position, symmetry, and dispersion of the surface-state bands observed experimentally are reproduced by the theoretical calculation. The first moment of the surface density of states (DOS) is shifted towards the Fermi level by ≊0.5 eV, suggesting that the surface Ni and Al atoms in the alloy have recovered some of their individual bonding behavior. However, the total surface DOS at the Fermi level shows negligible change from that of the bulk, thus indicating the absence of a magnetic surface layer.