Interface magnetism in metals: Ag/Fe(001)

A study of the effect of an ordered overlayer of Ag on the magnetism of an Fe(001) surface is presented. In order to understand the changes induced at the Ag/Fe interface, a series of self-consistent spin-polarized local-spin-density calculations were carried out with the use of our allelectron, full-potential, linearized augmented-plane-wave method. While the charge density is found to approach the bulk value within approximately one layer of the interface, the spin density at the interface is found to be strongly perturbed. An enhancement of the Fe magnetic moment at the interface (to 2.52 ${\mathrm{\mu }}_{\mathit{B}}$/atom) is predicted which, however, is significantly less than that found for the clean Fe(001) surface (2.95 ${\mathrm{\mu }}_{\mathit{B}}$). The role of the Ag overlayer in delocalizing the Fe surface states responsible for the increased surface magnetization and the effect on the single-particle spectra is described and discussed. The effect of the surface and interface on the contact hyperfine fields is evaluated: The (negative) core-polarization contribution is found to scale with the moment, but the valence contribution changes sign from negative in the interior to positive at the surface. The physical basis and the relationship of these results to the interpretation of Mössbauer-effect measurements of the hyperfine field are described.