Micromagnetic simulation of neutron scattering from spherical nanoparticles: Effect of pore-type defects

Abstract

We employ micromagnetic simulations to model the effect of pore-type microstructural defects on the magnetic small-angle neutron scattering cross section and the related pair-distance distribution function of spherical magnetic nanoparticles. Our expression for the magnetic energy takes into account the isotropic exchange interaction, the magnetocrystalline anisotropy, the dipolar interaction, and an externally applied magnetic field. The signatures of the defects and the role of the dipolar energy are highlighted and the effect of a particle-size distribution is studied. The results serve as a guideline to the experimentalist.

On the angular anisotropy of the randomly averaged magnetic neutron scattering cross section of nanoparticles

“…Nonuniformities in the magnetization distribution of nanoparticles are e.g. caused by surface anisotropy, vacancies or antiphase boundaries (Nedelkoski et al, 2017;Ijiri et al, 2019;Za ´kutna ´et al, 2020;Lak et al, 2021;Ko ¨hler et al, 2021;Honecker et al, 2022;Adams et al, 2022b,a;Sinaga et al, 2023). Micromagnetic simulations that take into account the relevant interactions such as isotropic exchange, antisymmetric exchange, magnetic anisotropy, Zeeman energy and the magnetodipolar interaction are an important tool for advancing the understanding of magnetic SANS of nanomagnets (Michels, 2021).…”