Magnetic Behaviour of Assemblies of Interacting Cobalt-Carbide Nanoparticles

TL;DR

This paper models the magnetic interactions in cobalt-carbide nanoparticle assemblies, revealing that anisotropy, defects, and inhomogeneities collectively influence their temperature-dependent magnetic properties.

Contribution

It provides a comprehensive model of nanoparticle interactions, highlighting the combined effects of anisotropy, defects, and inhomogeneities on magnetic behavior.

Findings

Magnetocrystalline anisotropy alone cannot explain large hysteresis from 50K to 400K.

Defects and inhomogeneities significantly influence magnetic pinning.

Particle size and orientation distribution affect temperature-dependent magnetization.

Abstract

Recent work [1] demonstrated high coercivity and magnetic moment in cobalt carbide nanoparticle assemblies and explained the high coercivity from first principles in terms of the high magnetocrystalline anisotropy of the cobalt carbide nanoparticles. In this work, we comprehensively model the interaction between the nanoparticles comprising the assembly and systematically understand the effect of particle size, distribution of the orientations of the nanoparticles' magnetocrystalline anisotropy axis with respect to the applied magnetic field, and dipole coupling between nanoparticles on the temperature dependent magnetic behavior of the nanoparticle assembly. We show that magnetocrystalline anisotropy alone is not enough to explain the large hysteresis over the 50K-400K temperature range and suggest that defects and inhomogeneties that pin the magnetization could also play a significant role on this temperature dependent magnetic behavior.