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Small‐angle neutron scattering correlation functions of bulk magnetic materials
Author(s) -
Mettus Denis,
Michels Andreas
Publication year - 2015
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576715013187
Subject(s) - condensed matter physics , small angle neutron scattering , magnetization , neutron scattering , ferromagnetism , magnetic anisotropy , materials science , anisotropy , saturation (graph theory) , scattering , physics , magnetic field , optics , mathematics , quantum mechanics , combinatorics
On the basis of the continuum theory of micromagnetics, the correlation function of the spin‐misalignment small‐angle neutron scattering cross section of bulk ferromagnets ( e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin‐misalignment scattering dΣ M /dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣ M /dΩ ( e.g. the angular anisotropy on a two‐dimensional detector or the asymptotic power‐law exponent) are determined by the ratio of magnetic anisotropy field strength H p to the jump Δ M in the saturation magnetization at internal interfaces. Here, the corresponding one‐ and two‐dimensional real‐space correlations are analyzed as a function of applied magnetic field, the ratio H p /Δ M , the single‐particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel.