A density functional theory study of Mn nanowires on the Si(001) surface

The structure of experimentally observed Mn nanolines on the Si(001) surface is investigated using density functional theory (DFT) and the DFT + U method. A candidate line structure consisting of a two-atom sub-unit is proposed, based on total energy and appearance in simulated scanning tunnelling microscopy images. The electronic and magnetic properties of this structure are investigated. The atoms in the line are strongly antiferromagnetically coupled with individual Mn atoms having moments of 4 µ(B). The atoms in the sub-unit are seen to move further apart by 0.57 Å upon forcing ferromagnetic alignment.