Ab initio study of ultrathin MgO films on Fe(001):: Influence of interfacial structures

The formation of MgO films on Fe(001) surfaces was studied using the ab initio electronic structure calculations based on the density functional theory. The free energy calculations in this study show that under Mg-rich conditions, the simple MgO/Fe(001) interface structure was favored, and under O-rich conditions, the oxidized MgO/FeO/Fe(001) interface structure was favored more than the simple interface structure. This indicates that it is possible to control the atomic structure at the MgO/Fe interface by varying the O/Mg excess during the film growth. The calculated structural parameters agreed well with those of previous experiments. Also examined were the electronic structures of the MgO/Fe(001) and MgO/FeO/Fe(001) interfaces. It was found that the atomic structure at the interface significantly affects the electronic and magnetic properties of the oxide/metal junctions.