Enhanced surface and interface magnetism of bcc Ni overlayers on Fe(001)

Abstract

The surface and interface magnetism of metastable bcc Ni as an overlayer on Fe(001)—originally synthesized by Heinrich et al.$mdash—is investigated using the highly precise total-energy full-potential linearized augmented plane-wave method. Two systems—a monolayer (1Ni/Fe) and a bilayer (2Ni/Fe) coverage on Fe(001)—are investigated and compared. The Ni-Fe interlayer spacings are found to be relaxed downward by 2.5% and 4% for 1Ni/Fe and 2Ni/Fe, respectively. The effect of the Ni-Fe hybridization on the electronic and magnetic properties is examined. In both overlayer systems the magnetic moments at the interface Ni and Fe sites are enhanced relative to their corresponding bulk values. The magnetic moment (0.69${\mathrm{\mu }}_{\mathit{B}}$) of the surface Ni atom of 2Ni/Fe is found to be reduced from that (0.86${\mathrm{\mu }}_{\mathit{B}}$) of the surface Ni atom on 1Ni/Fe. A manifestation of the moment enhancement at the interface Fe site is a positive contribution to the hyperfine field from the valence electrons.