Based on micromagnetic theory, we have derived analytical expressions for the magnetic small-angle neutron scattering (SANS) cross section of a two-phase particle-matrix-type ferromagnet. The approach---valid close to magnetic saturation---provides access to several features of the spin structure, such as perturbing magnetic anisotropy and magnetostatic fields. Depending on the applied magnetic field and on the magnitude Hₚ of the magnetic anisotropy field relative to the magnitude ΔM of the jump in the longitudinal magnetization at the particle-matrix interface, we observe a variety of angular anisotropies in the magnetic SANS cross section. In particular, the model explains the ``clover-leaf''-shaped angular anisotropy, which was previously observed for several nanostructured magnetic materials, and provides access to the magnetic interaction parameters, such as the average exchange-stiffness constant. It is also shown that the ratio Hₚ/ΔM decisively determines the asymptotic power-law exponent and the range of spin-misalignment correlations.
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Honecker et al. (2013) studied this question.
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