Magnetic neutron scattering on nanocomposites: Decrypting cross-section images using micromagnetic simulations

We have used numerical micromagnetics for the calculation of the magnetic (small-angle) neutron scattering cross section dΣM/dΩ of nanocomposites. In contrast to neutron experiments, in which one generally measures only a weighted sum of the Fourier components of the magnetization, our approach allows one to study the behavior of the individual contributions to dΣM/dΩ. The procedure furnishes unique and fundamental information regarding the magnetic microstructure and corresponding magnetic scattering from nanomagnets. In particular, our simulations explain the recent observation of magnetodipolar correlations in two-phase nanocomposites and, moreover, suggest their relevance for a wide range of magnetic materials such as nanocomposites, nanoporous magnets, single-phase magnets with random anisotropy, and magnetic recording media.