Oxidization engineered Dzyaloshinskii-Moriya interaction and topological magnetism at Fe/MgO bilayers

Abstract

Fe/MgO system is the one of the most important material prototypes in modern magnetic devices owing to its rich physics such as large perpendicular magnetic anisotropy and magnetoresistance effect. However, both large Dzyaloshinskii-Moriya interaction (DMI) and the topological magnetism that are mostly observed in heavy metals/ferromagnet (oxide) heterostructures have not been reported in this system. Here, we present evidence for sizable DMI that is even comparable to the Co/Pt interface can also be realized at pure and oxidized Fe/MgO bilayers due to the Rashba effect. More importantly, we find that both the strength and chirality of DMI can be engineered via interfacial oxygen manipulation, e.g., oxidization degree. The microscopic mechanism of oxidization inducing 3d orbitals reconstruction of Fe atoms dominates the variation of DMI is also unveiled. Using micromagnetic simulations, we further confirm that zero-field chiral spin textures can be achieved at the designed Fe/MgO films. These results not only enrich the physics of Fe/MgO interface but also provide a possible strategy to tailor noncolinear magnetic interaction and topological magnetism in the ferromagnet/oxide system.