Dresden 2017 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 39: Thin Film Applications

DS 39.5: Vortrag

Donnerstag, 23. März 2017, 10:30–10:45, CHE 91

Optical Investigation of Structural Disorder in Normal Spinel Ferrites in Relation to Magnetic Properties — •Vitaly Zviagin¹, Yogesh Kumar¹, Paula Huth², Israel Lorite¹, Annette Setzer¹, Daniel Spemann³, Jan Meijer¹, Reinhard Denecke², Pablo Esquinazi¹, Marius Grundmann¹, and Rüdiger Schmidt-Grund¹ — ¹Universtät Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, Germany — ²Universtät Leipzig, Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Linnéstr. 2, Germany — ³Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstr. 15, Germany

We present an optical investigation of structural disorder in spinel ferrites grown at different temperatures and pressures on MgO (100) and SrTiO₃ (100) substrates by pulsed laser deposition. Optical transitions in the diagonal elements of the dielectric tensor, obtained by spectroscopic ellipsometry, were identified and related to the presence of Fe²⁺ and Fe³⁺ cations located at different lattice sites corresponding to disorder and inversion of the normal crystal structure. Procedures such as annealing and irradiation with Si ions were applied to induce disorder and to alter the crystal structure of the investigated thin films. A direct correlation between the overall magnetic response, measured by SQUID, and the presence of Fe³⁺ on the tetrahedral lattice sites has been found and can be explained by the ferrimagnetic order of the crystal due to the dominating nature of the oxygen mediated coupling between the tetrahedral and octahedral lattice sites.