Nanopartículas magnéticas adsorvidas em superfícies metálicas

Abstract

Understand the physical properties of magnetic systems adsorbed in metallic surfaces is quite important for technological and scientific reasons. Here, this kind of system is studied theoretically by first principles calculations, based on the density functional theory (DFT), as well as by tight binding models. We study different Fe-based structures adsorbed on the Cu(001) surface. The systems studied here include Fe adatoms, dimers and wires and we also study the adsorption of Fe adatoms on Cu(001) surfaces that already contain some kind of magnetic impurity. We are specially interested on the changes in the physical properties of the magnetic structures while they interact with the metallic surface. The structural, energetic and electronic properties of the adsorbed systems are compared with the isolated systems. For instance, we compare the Fe d-orbitals density of states, which are known to be related to the magnetic properties of this kind of material. We also estimate the Heisenberg magnetic couplings using our total energy DFT results. It is also relevant, to study the magnetic coupling as a function of the distance between magnetic entities. For large distantes, it is not possible to perform first principles calculations in this kind of situation. Thus, in this cases, we use simplified tight binding models. We find power laws for the asymptotic behavior of the magnetic coupling as a function of the distance between magnetic entities or as a function of the number of non-magnetic spacers.