Structural and magnetic investigation of the interfaces of with and without NiO interlayer

Pohlmann T, Bertram F, Thien J, et al. Structural and magnetic investigation of the interfaces of with and without NiO interlayer. Physical Review B. 2022;105(23): 235436.We present an investigation on the structural and magnetic properties of the interfaces of Fe3O4/MgO(001) and Fe3O4/NiO/MgO(001) by extracting cation-selective magneto-optical depth profiles by means of x-ray resonant magnetic reflectivity in combination with charge-transfer multiplet simulations of x-ray magnetic circular dichroism data. For Fe3O4/MgO(001), the magneto-optical depth profiles at the Fe2+oct and the Fe3+oct resonant energies follow exactly the structural profile, while the magneto-optical depth profile at the Fe3+tet resonance is offset by 3.2±1.3 Å from the interface, consistent with a B-site interface termination of Fe3O4 with fully intact magnetic order. In contrast, for Fe3O4/NiO(001), the magneto-optical depth profiles at the Fe2+oct and the Ni2+ resonances agree with the structural profile, but the interface positions of the magneto-optical depth profiles at the Fe3+oct and the Fe3+tet resonances are spatially shifted by 3.3±1.4 and 2.7±0.9 Å, respectively, not consistent with a magnetically ordered stoichiometric interface. This may be related to an intermixed (Ni,Fe)O layer at the interface. The dichroic depth profile at the Ni L3 edge might hint at uncompensated magnetic moments throughout the NiO film