New Methodology for Micromagnetic Simulations of Nanocomposites With Applications to SANS Experiments

We present a new micromagnetic methodology for numerical simulations of magnetic nanocomposites. The methodology is especially suitable for simulating two-phase systems consisting of magnetically “hard” inclusions in a “soft” magnetic phase, because it avoids the unnecessary discretization of “hard” inclusions, allowing simultaneously an arbitrary fine discretization of the “soft” phase. As an application example of this novel concept we have calculated the equilibrium magnetization distribution of the iron-based nanocomposite Fe-Zr-B-Cu (Nanoperm) and the corresponding small-angle neutron scattering (SANS) cross-sections. For this system we could achieve a remarkable agreement between not-trivial SANS cross-sections obtained experimentally (the so called “clover-leaf-shaped” pattern from Michels , Phys. Rev. B, 74, 134407, 2006) and those calculated numerically.