Role of surface disorder on the magnetic properties and hysteresis of nanoparticles

TL;DR

This study uses Monte Carlo simulations to explore how surface disorder and anisotropy affect the magnetic behavior and hysteresis of ferrimagnetic nanoparticles, revealing surface-induced structures alter reversal mechanisms.

Contribution

It introduces a detailed simulation of surface anisotropy effects on nanoparticle magnetization, highlighting the formation of hedgehog-like structures and their impact on reversal processes.

Findings

Surface anisotropy induces hedgehog-like structures.

Reversal mechanisms change with increased surface anisotropy.

Surface disorder significantly influences magnetic properties.

Abstract

We present the results of Monte Carlo simulations of a model of a single maghemite ferrimagnetic nanoparticle including radial surface anisotropy distinct from that in the core with the aim to clarify what is its role on the magnetization processes at low temperatures. The low temperature equilibrium states are analized and compared to those of a ferromagnetic particle with the same lattice structure. We have found that the formation of hedgehog-like structures due to increased surface anisotropy is responsible for a change in the reversal mechanism of the particles.