Influence of oxygen vacancies on the magnetic properties of ZnFe2O4

K. L. SALCEDO RODRÍGUEZ; M. HOFFMANN; J. J: MELO QUINTERO; G. PASQUEVICH; P. MENDOZA ZELIS; L. A. ERRICO; S. STEWART; W HERGERT .; C. RODRÍGUEZ TORRES

Berlin

Congreso; 79. Jahrestagung der DPG und DPG-Frühjahrstagung (79a Reunión Anual de la Sociedad Alemana de Física- por sus siglas en alemán:DPG- y DPG Primavera),; 2015

Technische Universität Berlin, Berlin, Alemania

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 agnetization, 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.