Magnetic properties of Fe overlayers on W(001) and the effects of oxygen adsorption.

Abstract

The structural and magnetic properties of Fe monolayers and bilayers on the W(001) substrate and the effects of oxygen adsorption were determined using the all-electron total-energy local-density full-potential linearized augmented plane-wave method. The strong ferromagnetism of the free Fe monolayer is completely destroyed by the Fe-W interaction for monolayer Fe/W(001); instead, a c(2\ifmmode\times\else\texttimes\fi{}2) antiferromagnetic configuration becomes the ground state. For bilayer Fe/W(001), a tetragonal rather than bcc structure is formed. The ferromagnetism of the previous ``dead'' Fe layer is restored by the additional adsorbed Fe layer; the magnetic moment in the interface and surface Fe layers increase to 1.68${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ and 2.43${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$, respectively. These ferromagnetic Fe layers induce a sizable magnetic moment (0.22${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$) in the interfacial W layer. Finally, oxygen adsorption on bilayer Fe/W(001) is found to decrease greatly the magnetism of the interfacial Fe layer---to only 0.7${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$---but not to affect the top Fe layer.