Size-dependent spatial magnetization profile of manganese-zinc ferrite Mn0.2Zn0.2Fe2.6O4 nanoparticles

TL;DR

This study uses small-angle neutron scattering to investigate how the magnetization profile of manganese-zinc ferrite nanoparticles varies with size, revealing a transition from uniform to nonuniform magnetization as particles grow larger.

Contribution

It provides the first detailed size-dependent analysis of magnetization profiles in Mn-Zn ferrite nanoparticles combining experimental SANS data with micromagnetic simulations.

Findings

Smaller particles are homogeneously magnetized.

Larger particles show nonuniform magnetization profiles.

Field strength reduces internal spin disorder.

Abstract

We report the results of an unpolarized small-angle neutron scattering (SANS) study on Mn-Zn ferrite (MZFO) magnetic nanoparticles with the aim to elucidate the interplay between their particle size and the magnetization configuration. We study different samples of single-crystalline MZFO nanoparticles with average diameters ranging between 8 to 80 nm, and demonstrate that the smallest particles are homogeneously magnetized. However, with increasing nanoparticle size, we observe the transition from a uniform to a nonuniform magnetization state. Field-dependent results for the correlation function confirm that the internal spin disorder is suppressed with increasing field strength. The experimental SANS data are supported by the results of micromagnetic simulations, which confirm an increasing inhomogeneity of the magnetization profile of the nanoparticle with increasing size. The results presented demonstrate the unique ability of SANS to detect even very small deviations of the magnetization state from the homogeneous one.