First-principles study of ultrathin magnetic Mn films on W surfaces.

The structural and magnetic properties of static compact thin Mn films deposed on W(100) and W(110) substrates have been investigated in the framework of the density functional theory. In good agreement with experiments, pseudomorphically adsorbed Mn films up to three monolayers (ML) are found to be stable despite the huge tensile strain induced by the epitaxial conditions. For $\mathrm{Mn}∕\mathrm{W}\left(110\right)$ our results demonstrate a $c(2\times 2)$ in-plane antiferromagnetic order for thicknesses up to 3 ML, with a degenerated layered antiferromagnetism in the (110) planes for 3 ML thick $\mathrm{Mn}∕\mathrm{W}\left(110\right)$ films. For $\mathrm{Mn}∕\mathrm{W}\left(110\right)$ our calculations predict a ferromagnetic arrangement in 1 and 2 ML thick films stabilized by the hybridization with the substrate, with a transition to an antiferromagnetism layered in (100) planes at higher thickness. The effects induced by the reduced dimensionality are discussed based on the comparison with bulk Mn and free-standing Mn ML. The magnetic contribution to the adsorption is determined by comparing magnetic and nonmagnetic calculations.