Weak ferromagnetic component on the bulk ZnFe2O4 compound

Abstract

Magnetization data on the bulk ZnFe2O4 antiferromagnetic compound (TN≈10K) obtained via solid state reaction at different synthesis temperatures show one weak ferromagnetic component at room temperature. We have related it with the cationic disorder effect present on spinel structure of our bulk samples which comes from the magnetic interaction between iron ions sit on both octahedral and tetrahedral sites. The magnetization measurements show to all samples a clear peak around 10K consistent with the antiferromagnetic phase transition. On the other hand, after extracted the paramagnetic component, the hysteresis loops measured at room temperature display one weak ferromagnetic component. Once the T-dependence of magnetization does not fit to a Curie–Weiss law to temperatures well above the magnetic transition we have used a combination of the Curie–Weiss law (paramagnetic spins) and a typical temperature dependence of M0, M0(T)=M0(0)[1−(T/TC)2]0.5 (ordered ferromagnetic spins). We note an increase of the M0(0) as function of the synthesis temperature. This reinforce our supposition of a cationic disorder effect driving the system to present two kinds of magnetic interactions between iron ions on A and B sites.