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arXiv · 2111.13125

Structural and magnetic investigation of the interfaces of $\mathrm{Fe_3O_4/MgO(001)}$ with and without NiO interlayer

Tobias Pohlmann·Florian Bertram·Jannis Thien·Jari Rodewald·Kevin Ruwisch·Timo Kuschel·Eugen Weschke·Karsten Küpper·Joachim Wollschläger
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Abstract

We present an investigation on the structural and magnetic properties of the interfaces of $\mathrm{Fe_3O_4/MgO(001)}$ and $\mathrm{Fe_3O_4/NiO/MgO(001)}$ by extracting cation-selective magnetooptical depth profiles by means of x-ray magnetic reflectivity (XRMR) in combination with charge-transfer multiplet simulations of x-ray magnetic circular dichroism (XMCD) data. For $\mathrm{Fe_3O_4/MgO(001)}$, the magnetooptical depth profiles at the $\mathrm{Fe^{2+}_{oct}}$ and the $\mathrm{Fe^{3+}_{oct}}$ resonant energies follow exactly the structural profile, while the magnetooptical depth profile at the $\mathrm{Fe^{3+}_{tet}}$ resonance is offset by $3.2\pm1.3\,$\r{A} from the interface, consistent with a B-site interface termination of $\mathrm{Fe_3O_4}$ with fully intact magnetic order. In contrast, for $\mathrm{Fe_3O_4/NiO(001)}$, the magnetooptical depth profiles at the $\mathrm{Fe^{2+}_{oct}}$ and the $\mathrm{Ni^{2+}}$ resonances agree with the structural profile, but the interface positions of the magnetooptical depth profiles at the $\mathrm{Fe^{3+}_{oct}}$ and the $\mathrm{Fe^{3+}_{tet}}$ resonances are laterally shifted by $3.3\pm 1.4\,$\r{A} and $2.7\pm0.9\,$\r{A}, respectively, not consistent with a magnetically ordered stoichiometric interface. This may be related to an intermixed $\mathrm{(Ni,Fe)O}$ layer at the interface. The magnetooptical depth profiles at the Ni $L_3$ edge reveal uncompensated magnetic moments throughout the NiO film.

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Tobias Pohlmann, Florian Bertram, Jannis Thien, Jari Rodewald, Kevin Ruwisch, Timo Kuschel, Eugen Weschke, Karsten Küpper, Joachim Wollschläger. 2021-11-25. Structural and magnetic investigation of the interfaces of $\mathrm{Fe_3O_4/MgO(001)}$ with and without NiO interlayer. https://doi.org/10.1103/physrevb.105.235436

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