First-principles investigation of the formation of Mn/Ag(100) surface alloy

We present nb initio results for the interdiffusion energy and the formatio n energy of Mn/Ag(100) surface, subsurface and bilayer surface alloy films. From these results we conclude that in contrast with the Mn/Cu(100) system , which favours the formation of the Cu(100)-c(2 x 2) Mn surface alloy, the lowest-energy configuration is a c(2 x 2) antiferromagnetic Mn monolayer l ocated in the second atomic layer below the Ag(100) surface. Antiferromagne tic monolayers being located in deeper layers show a slightly higher energy . Depending on the growth conditions, we expect on the basis of these resul ts that Mn atoms diffuse into subsurface layers and form small Mn clusters. Superposition of Mn monolayers and Ag(100)-c(2 x 2) Mn layers in the secon d layer or a superposition of the monolayer with c(2 x 2) bilayer alloys ma y be intermediate metastable configurations. Total energy results are based on the density functional theory in the local-spin-density approximation a nd are carried out using the full-potential linearized-augmented-plane-wave method in film geometry.