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HL 66.3: Vortrag
Donnerstag, 19. März 2020, 11:30–11:45, CHE 91
Ellipsometric study of defect induced magnetism in spinel ferrite thin films — •Vitaly Zviagin1, Chris Sturm1, Pablo Esquinazi1, Marius Grundmann1, and Rüdiger Schmidt-Grund1,2 — 1Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik — 2Now at: Technische Universität Ilmenau, Institut für Physik
We present the magnetic properties of normal spinel ZnFe2O4 (ZFO) thin films in dependence on fabrication and annealing temperature as well as atmosphere. The increase in the net magnetic response with decreasing substrate temperature correlates with the increase in cation disorder, evident by an increase in O2−2p-FeTd3+3d electronic transition amplitude in the dielectric function (DF) spectra. Absorption in the low energy range (∼0.9 eV) is related to an electronic transition between d orbitals of Fe2+ and Fe3+ cations and shows a strong dependence on fabrication and annealing atmosphere. Comparing the cation distribution in film bulk (optical transitions in the DF) to near-surface region (X-ray absorption), it is found that an inhomogeneous cation distribution leads to a weaker magnetic response in films of inverse configuration, whereas defects in normal spinel are likely to be found at the film surface. The presented results show that it is possible to engineer and to probe the defect distribution in the magnetic spinel ferrite film structure and to tailor their magnetic properties on demand.
 V. Zviagin et al., Appl. Phys. Lett. 108, 13 (2016)