Uniaxial polarization analysis of bulk ferromagnets: theory and first experimental results. Issue 3 (28th May 2022)

• Record Type: Journal Article
• Authors: Malyeyev, Artem; Titov, Ivan; Dewhurst, Charles; Suzuki, Kiyonori; Honecker, Dirk; Michels, Andreas
• Is Part Of: Journal of applied crystallography. Volume 55:Issue 3(2022)
• Page Start: 569
• Page End: 585
• Publication Date: 2022-05-28
• Subjects: polarized neutron scattering -- uniaxial polarization analysis -- small‐angle neutron scattering -- micromagnetics -- magnetic nanocomposites; Crystallography -- Periodicals; 548.05
• DOI: 10.1107/S1600576722003508
• Languages: English
• ISSNs: 0021-8898

Abstract

Abstract : Based on the continuum theory of micromagnetics, theoretical expressions for the polarization of the scattered neutron beam in uniaxial small‐angle neutron scattering have been derived and their predictions tested by analyzing experimental data on a soft magnetic nanocrystalline alloy. The here‐presented theoretical framework forms the basis for polarized real‐space methods such as spin‐echo small‐angle neutron scattering, spin‐echo modulated small‐angle neutron scattering and polarized neutron dark‐field contrast imaging. Abstract : On the basis of Brown's static equations of micromagnetics, the uniaxial polarization of the scattered neutron beam of a bulk magnetic material is computed. The approach considers a Hamiltonian that takes into account the isotropic exchange interaction, the antisymmetric Dzyaloshinskii–Moriya interaction, magnetic anisotropy, the dipole–dipole interaction and the effect of an applied magnetic field. In the high‐field limit, the solutions for the magnetization Fourier components are used to obtain closed‐form results for the spin‐polarized small‐angle neutron scattering (SANS) cross sections and the ensuing polarization. The theoretical expressions are compared with experimental data on a soft magnetic nanocrystalline alloy. The micromagnetic SANS theory provides a general framework for polarized real‐space neutron methods, and it may open up a new avenue for magnetic neutron data analysis on magnetic microstructures.