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DS: Fachverband Dünne Schichten

DS 6: Thin Film Applications

DS 6.5: Vortrag

Montag, 12. März 2018, 16:00–16:15, H 0111

The Influence of Crystallographic Order on Ferrimagnetic Response of Spinel ZnFe₂O₄ Thin Films — •Vitaly Zviagin, Yogesh Kumar, Chris Sturm, Israel Lorite, Pablo Esquinazi, Marius Grundmann, and Rüdiger Schmidt-Grund — Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Linnéstr. 5, Leipzig

We present the dielectric function of normal spinel ZnFe₂O₄ (ZFO) grown at different pressures and temperatures on SrTiO₃ (100) substrate by pulsed laser deposition. Electronic transitions visible in the diagonal element of the dielectric tensor are assigned to transitions involving Fe²⁺, Fe³⁺ and Zn²⁺ cation 3d and 4s orbitals. Transitions from O_2p to tetrahedrally coordinated Fe³⁺ cation, located at ∼ 3.5 eV, and between octahedrally coordinated Fe²⁺ cations, located at ∼ 0.9 eV, give evidence to disorder in the normal spinel structure. Growth temperature dependent investigation has shown a direct correlation between saturation magnetization at 5 K and the amplitude of the former mentioned transition, likely due to the dominant nature of the oxygen mediated coupling between Fe³⁺ located on two different lattice sites.[1] Annealing films at temperatures greater than 250 ^∘C in argon and oxygen atmospheres facilitates a decrease in the ferrimagnetic response and is explained by reordering of the disordered spinel structure toward ordered normal state. A direct correlation between the disorder cation transition contributions to the dielectric function and room temperature ferrimagnetic response is shown.
V. Zviagin et al., Appl. Phys. Lett. 108, 13 (2016)