Magnetism at the Ni(001) surface: A high-precision, all-electron local-spin-density-functional study

Abstract

We present the results of high-precision, all-electron, self-consistent local-spin-density-functional calculations on a seven-layer Ni(001) film using the full-potential linearized-augmented-plane-wave method. It is found that the surface atoms have a magnetic moment which is enhanced by almost 20% compared with the bulklike atoms in the interior of the film. There is no indication of a Friedel-type oscillation in the layer-by-layer magnetic moments. Although the negative core-contact spin densities for the surface atoms are enhanced in magnitude by 20%, the contribution from the (4s-derived) valence electrons changes sign and becomes slightly positive in the surface layer. This causes a net decrease in magnitude of the total contact spin density by 20%. In agreement with photoemission experiments we find the majority-spin ${\overline{M}}_3$ surface state to be occupied, contrary to the early results of Wang and Freeman for a nine-layer film and to recently presented results obtained by Jepsen et al. on a five-layer film. The work function is found to be 5.37 eV, in good agreement with the experimental value of 5.22±0.04 eV. For the core levels of the surface atoms we obtain a shift between 0.3 and 0.5 eV towards reduced binding energies which is explained in terms of $d$-band narrowing and layer-by-layer charge neutrality.