Oxygen-vacancy-induced local ferromagnetism as a driving mechanism in enhancing the magnetic response of ferrites

CLAUDIA RODRIGUEZ TORRES; PASQUEVICH, GUSTAVO A.; PEDRO MENDOZA ZÉLIS; F.GOLMAR; S.H. HELUANI; SANJEEV K NAYAK; WAHEED A ADEAGBO; WOLFRAM HERGERT; MARTIN HOFFMANN; ARTHUR ERNST; P. ESQUINAZI; S.J. STEWART

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2014 vol. 89 p. 104411 - 1044118

1098-0121

This work probes the relevance of oxygen vacancies in the formation of local ferromagnetic coupling between Fe ions at octahedral sites in zinc ferrites. This coupling gives rise to a ferrimagnetic ordering with the Curie temperatures above room temperature in an otherwise antiferromagnetic compound. This conclusion is based on experimental results from X-ray magnetic circular dichroism measurements at the Fe L2,3 edges and magnetization measurements performed on zinc ferrites, nanoparticles and films, with different cation distributions and oxygen vacancy concentrations. Our observations are confirmed by density functional theory calculations and indicate that the enhanced ferrimagnetic response observed in some nominally nonmagnetic or antiferromagnetic ferrites can be taken as a further example of the defect-induced magnetism phenomenon.