Synthesis of Fe3O4@CoFe2O4@MnFe2O4 trimagnetic core/shell/shell nanoparticles

TL;DR

This paper reports the synthesis and detailed magnetic characterization of novel multishell Fe3O4@CoFe2O4@MnFe2O4 nanoparticles, revealing that adding a soft ferrite shell unexpectedly increases coercivity, challenging simple magnetic models.

Contribution

It introduces a new synthesis method for multishell magnetic nanoparticles and demonstrates that shell interactions significantly influence magnetic properties.

Findings

Adding a second soft shell enhances coercivity contrary to simple models.

Shell interactions must be considered to understand magnetic behavior.

Multishell structure offers tunable magnetic properties.

Abstract

We report the synthesis and characterization of original 'multishell' magnetic nanoparticles made of a soft core (magnetite) covered with two successive shells: a hard one (cobalt ferrite) and then a soft one (manganese ferrite). Our results show that contrary to expectations from simple models in which the coercivity of a bimagnetic core/shell nanoparticle depends simply on the proportion of soft and hard phases within that particle, the addition of a second shell made of a soft ferrite material enhances the coercivity. Taking into account the interactions between the shells themselves and the core may thus be necessary to understand the magnetic properties of such nanoparticles.