Epitaxial strain and interfacial electronic topological transition in O-rich MgO/FeO/Fe(001) interfaces

The effects of epitaxial strain on the electronic properties of MgO/FeO/Fe(001) interfaces were studied using ab initio density-functional-theory calculations. It was shown that epitaxial strain induces significant changes in the interfacial band structures of FeO: In the case of tensile strain, band narrowing of the interfacial spin-majority (MJ) states was observed, while in the case of compressive strain, band broadening was observed. Under a 5.8% tensile strain corresponding to the lattice constant of bulk MgO, the top of the interfacial spin-MJ band moved down in energy to the extent that the interfacial spin-MJ density of states at the Fermi energy disappeared. This indicates that the interfacial electronic transition occurred from ferromagnetic to half metallic states. Herein we refer to this transition as the interfacial electronic topological transition.