The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

TLDR

Recent advances in magnetic materials emphasize that new magnetic nanoparticles require an accurate understanding of their collective magnetic behavior, and that magnetic properties are strongly affected by anisotropy and interparticle interactions. The study investigates how magnetic anisotropy and interparticle interactions influence the properties of ferrite nanoparticles. Co_xFe_{3−x}O_4 nanoparticles (x = 0–1) were synthesized to span soft to hard ferrites, with phase purity confirmed by Rietveld refinement, and their structure, morphology, magnetic properties, and interparticle interactions were examined using δm graphs and Henkel plots. Hyperthermia measurements showed that soft Fe3O4 nanoparticles exhibit about four times higher heating efficiency than hard CoFe2O4, attributed to the high coercive field relative to the applied field amplitude.

Abstract

Recent advances in the field of magnetic materials emphasize that the development of new and useful magnetic nanoparticles (NPs) requires an accurate and fundamental understanding of their collective magnetic behavior. Studies show that the magnetic properties are strongly affected by the magnetic anisotropy of NPs and by interparticle interactions that are the result of the collective magnetic behavior of NPs. Here we study these effects in more detail. For this purpose, we prepared Co x Fe 3− x O 4 NPs, with x = 0–1 in steps of 0.2, from soft magnetic (Fe 3 O 4 ) to hard magnetic (CoFe 2 O 4 ) ferrite, with a significant variation of the magnetic anisotropy. The phase purity and the formation of crystalline NPs with a spinel structure were confirmed through Rietveld refinement. The effect of Co doping on structure, morphology and magnetic properties of Co x Fe 3− x O 4 samples was investigated. In particular, we examined the interparticle interactions in the samples by δ m graphs and Henkel plots that have not been reported before in literature. Finally, we studied the hyperthermia properties and observed that the heat efficiency of soft Fe 3 O 4 is about 4 times larger than that of hard CoFe 2 O 4 ferrite, which was attributed to the high coercive field of samples compared with the external field amplitude.