Magnetism at high-index transition-metal surfaces and the effect of metalloid impurities: Ni(210)

Abstract

Structural, electronic, and magnetic properties near the Ni(210) surface and the effect of Li, B, P, and Ca impurities are determined by means of the all-electron total energy/atomic force full-potential linearized augmented plane wave method with the generalized gradient approximation. For the Ni(210) clean surface, simulated with an 11-layer slab, multilayer relaxation is found to be confined to the top three layers. The magnetic moment of the surface Ni layer, $0.79{\ensuremath{\mu}}_{B},$ is enhanced by 27%, compared with its bulk value. This result confirms the well-accepted understanding that the reduced coordination number at a clean transition-metal surface with a high index leads to enhanced magnetic moments. Boron and P strongly alter the atomic structure at the Ni(210) surface, whereas Li and Ca have only a slight influence, due to the weak chemical bonding with the nickel substrate. It is found that all four selected elements exert detrimental effects on the Ni(210) surface magnetism. The effects of B and P are stronger than those of Li and Ca, mainly due to their stronger hybridization with the nickel d states. An analysis of the results for B and P suggests that it is the stronger magnetization of its free standing monolayer that makes P more detrimental than B on the nickel surface magnetism.