Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 49: POSTER II
MA 49.33: Poster
Donnerstag, 19. März 2015, 15:00–18:00, Poster A
Influence of oxygen vacancies on the magnetic properties of ZnFe2O4 — •Karen L. Salcedo Rodríguez1, Martin Hoffmann2,3, Jhon J. Melo Quintero1, Gustavo Pasquevich1, Pedro Mendoza Zelis1, Leonardo A. Errico1, Silvana J. Stewart1, Wolfram Hergert2, and Claudia E. Rodríguez Torres1 — 1National University of La Plata, Argentina — 2Martin Luther University Halle-Wittenberg, Germany — 3Max Planck Institute for Microstructure Physics, Halle, Germany
We continue our experimental and theoretical study on bulk ZnFe2O4 (ZFO) powders [1]. ZFO samples were annealed in vacuum up to 600∘C to control and increase the number of oxygen vacancies. The x-ray diffraction patterns indicate that all samples consist of single-phase ferrite. However, the magnetic measurements show the coexistence of ferromagnetic-like and paramagnetic components. For the saturation magnetization, the paramagnetic susceptibility and the Mössbauer spectroscopy, we observed a qualitative difference for samples which were annealed at temperatures either below or above 400∘C.
Furthermore, we studied with ab initio calculations ZFO in the normal/inverted spinel structure and in the oxygen-deficient regime. The comparison between the experimental and calculated hyperfine parameters indicated a reduction of inversion by increasing the annealing temperature up to 400∘C. For higher temperatures, we attributed the oxygen vacancies formation for the observed increase in the saturation magnetization and paramagnetic susceptibility.
[1] PRB 89, 104411 (2014)