Micromagnetic studies of the domain structure of BaFe₁₂O₁₉ cubes in zero magnetic field

This article reports an investigation of the domain structure of cube-shaped BaFe₁₂O₁₉ models in zero magnetic field using the public-domain OOMMF micromagnetic simulator to model cubes with sides varying from 100 to 900 nm. A Bloch wall appears in BaFe₁₂O₁₉ cubes larger than about 510 nm and a single-domain structure appeared below 510 nm. The transition from single- to multiple- domain structure in the cube-shaped models occurred near the size predicted by analytical solutions of Kittel's equation. Analysis of the magnetization energy showed that the exchange energy increased with increasing size once the Bloch wall was formed. We also calculated the width of the Bloch walls from the full width at half maximum of the transverse component of the magnetization vector. The domain wall width increased, as the modeled cubes grew larger.