Comparison between a bilayer surface ordered alloy and an ideal Mn monolayer on Fe(001)

A recent proton-induced Auger electrons experiment indicates that significant interfacial alloying occurs during the growth of the first monolayer of Mn on Fe(001). Here we report on the stability of a two-dimensional (2D) Mn-Fe surface alloy versus a perfect Mn monolayer (ML) on Fe(001). Our calculations are performed with a cell of two inequivalent atoms per plane through an ab initio tight-binding linear muffin-tin orbital method in the atomic-sphere approximation. A 2-ML-thick ordered Mn0.5Fe0.5 surface alloy is shown to present an antiferromagnetic configuration in the Mn sublattice. The mean magnetic moment on the Mn atoms in this 2D Mn-Fe surface alloy is shown to be higher as compared to that of a perfect Mn monolayer on Fe(001) in the antiferromagnetic c(2 x 2) configuration. [S0163-1829(99)04334-9].