Magnetic phases in NiO and MnO ultrathin films: Finite thickness and strain effects

Abstract

Magnetic phases of NiO and MnO ultrathin films are established on the basis of a Hamiltonian including superexchange and dipolar interaction, disregarding the magnetocrystalline interaction because of its considerably smaller contribution in these films. The employed theoretical approach demonstrates that the finite thickness is substantially more important than the strain effect on the stabilization of the ground state configurations. An antiferromagnetic phase where ferromagnetic layers are piled up with alternating opposite in-plane orientations of the spins appears in NiO and MnO (111) ultrathin films, while a striped antiferromagnetic phase with the larger component of the magnetic moments along the growth direction is found in NiO and MnO (001) ultrathin films. These results are in qualitative agreement with available experimental results, but they disagree with the ones of a former theory, which is carefully examined.