Interparticle Interactions and Magnetic Anisotropy in CoFe2O4/ZrO2 Nanocomposites: Disentangling the Experimental Process from Matrix-Induced Effects

Abstract

The magnetic properties of hybrid nanocomposites arise from a complex interplay between effective anisotropy and interparticle interactions. Understanding the origin and the distinct contributions of these effects is essential for the rational engineering of materials with tailored magnetic behavior. Equally important is the fact that the experimental procedures used to prepare nanocomposites may themselves modify the intrinsic properties of the magnetic cores, through changes in shell uniformity, chemical composition, defect density, or interdiffusion, which in turn can affect effective anisotropy, interfacial coupling, and dipolar interactions. In this context, this study aims to disentangle the effects of the synthesis process and matrix-induced effects in CoFe2O4/ZrO2 (CFO@ZO) hybrid nanocomposites. The system consists of semi-hard-magnetic CoFe2O4 nanoparticles (average size ∼ 5 nm) encapsulated within a mesoporous ZrO2 matrix. Low-temperature δM-plots and M(H) curves show that the synthesis process alone significantly enhances dipolar interactions, whereas embedding the nanoparticles in ZrO2 partially suppresses these interactions while strongly influencing the effective magnetic anisotropy. Disentangling the effects of interparticle interactions and effective magnetic anisotropy demonstrated that the CFO@ZO magnetization-reversal process is governed primarily by the intrinsic magnetic anisotropy of individual particles, with minimal contribution from interparticle interactions.