Towards understanding MgO/Fe interface formation: Adsorption of O and Mg atoms on an Fe(001) surface

Abstract

We report results of first-principles study of the adsorption of atomic oxygen and magnesium on the Fe(001) surface. Two adsorption scenarios were considered. In the first process, the Mg atoms were adsorbed on the Fe(001) surface with preadsorbed O atoms, whereas in the second scenario metallic Mg preadsorbed on the Fe(001) surface was exposed to oxygen. For both O and Mg atoms, fourfold hollow sites were found as the energetically most favorable adsorption sites on the clean Fe(001) surface. The result of both adsorption scenarios was the formation of a MgO adlayer on the Fe(001) surface with a sharp MgO/Fe interface. In particular, the deposition of Mg atoms on O/Fe(001) showed that magnesium can pull out O adatoms from the Fe surface. Structural, electronic, and magnetic properties were analyzed as a function of O and Mg coverages. The calculated electronic structure and magnetic moments showed that the full MgO monolayer affects the properties of the Fe surface much weaker than an incomplete MgO adsorbate layer.