Modeling magnetic correlations in magnetite nanoparticle assemblies using x-ray magnetic scattering data

Magnetic nanoparticles are used in nanotechnologies and biomedical applications, such as drug targeting, MRI, and bio-separation. Magnetite (Fe₃O₄) nanoparticles stand to be effective in these roles due to the non-toxic nature of magnetite and its ease of manufacture. To this end, a greater understanding of the magnetic behavior of the individual magnetite nanoparticles is needed when a collection of them is used. This research seeks to discover the local magnetic ordering of ensembles of magnetite nanoparticles occurring at various stages of the magnetization process at temperatures above and below their blocking temperature for various particle sizes. We use x-ray circular dichroism (XMCD) and x-ray resonant magnetic scattering (XRMS), which provides information about the spatial magnetic orders in the material. Here we discuss the modeling of the XRMS data an empirical Gaussian packet model in q-space. We find that at low temperature and near the coercive point, inter-particle magnetic correlations emerge, including a combination of ferromagnetic and antiferromagnetic alignments of the nanospins.