Energy bands and magnetization of a Ni(001) monolayer

Abstract

The calculated energy bands of a Ni(001) monolayer with the bulk lattice parameter display a wide range of exchange splittings influenced by hybridization, potential anisotropy, and bonding differences. The magnetic moment $0.98{\mu }_B$ is 75% larger than the measured bulk value of $0.56{\mu }_B$, where ${\mu }_B$ is the Bohr magneton. Factors contributing to the increase of magnetization compared with the bulk behavior include narrowing and sharpening of the density of states, $p-d$ dehybridization, and increased occupation of the $\mathrm{sp}$ band. The majority-spin $d$ bands are full, in contradiction to previous calculations in which these bands rise above the Fermi energy near $\overline{M}$ in the surface Brillouin zone. Our results were obtained using a spin-polarized adaptation of the self-consistent localized-orbital method developed by Smith, Gay, and Arlinghaus. We used a new exchange-correlation potential derived from a recent analysis by Vosko, Wilk, and Nusair of the correlation energy of the spin-polarized electron liquid. Substitution of the von Barth—Hedin potential, which overestimates correlation effects, led to a reduction of the magnetic moment by 1%, and a reduction of the exchange splittings by 2—8%.