Ab initio study of the role of defects on the magnetic response and the structural, electronic and hyperfine properties of ZnFe2O4

RODRÍGUEZ TORRES, C.E.; MELO QUINTERO, J.J.; ERRICO, L.A.; SALCEDO RODRÍGUEZ, K.L.

JOURNAL OF ALLOYS AND COMPOUNDS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2019 vol. 775 p. 1117 - 1128

0925-8388

Articulo aceptado para su publicacion el 8/10/2019 y disponible online desde el 13/10/2018.Este articulo fue incluido en el informe del periodo 2017-2018 y NO DEBE SER CONSIDERADO EN EL INFORME 2019-2020.In this work the effects of defects (oxygen vacancies, cationic inversion) on the structural, electronic and the magnetic response of the spinel ZnFe2O4 (ZFO) are studied by using a density functional theory (DFT) based ab initio method (the Full-Potential Linearized Augmented Plane Waves plus Local Orbitals,LAPWþlo) on the framework of the Generalized Gradient Approximation plus U (GGAþU) level. The changes induced by the defects in the hyperfine interactions at the Fe sites of the structure are also presented. In order to discuss the magnetic ordering and the electronic structure of the system we considered different spin arrangements. We found that, similar to the normal and pristine case, reduced and partially inverted ZFO presents an energy landscape characterized by a large number of metastable states. Our calculations successfully describe the hyperfine properties (isomer shift, magnetic hyperfinefield and quadrupole splitting) at the Fe sites that are seen by M?ossbauer Spectrocopy (MS) at 4 and 300 K, enabling us to characterize the local structure around Fe atoms. Our LAPWþlo predictions also demonstrate the relevance of both oxygen vacancies and antisites (cationic inversion) in the formation oflocal ferromagnetic coupling between Fe ions, giving rise to a ferrimagnetic ordering in an otherwise antiferromagnetic compound. This results support conclusions based in experimental results obtained in x-ray magnetic circular dichroism and magnetization measurements performed on zinc ferrites withdifferent cation distributions and oxygen vacancy concentrations reported in the literature.