Stripe domain structures in a thin ferromagnetic film

Abstract

We present a theory of the stripe domain structure in a thin ferromagnetic film with single-ion easy-axis magnetic anisotropy and long-range dipole interactions, for a wide range of temperatures and applied magnetic field. The domains exist at temperatures below the reorientational phase transition from out-of-plane to in-plane magnetization. The system of stripes can be described as a liquid crystal with a preferred domain-wall orientation. The positional order is destroyed by both thermodynamical meandering of domain walls and by the proliferation of dislocations. Spatial anisotropy generated by the fourth-order exchange energy stabilizes the stripe domain structure and pins its orientation. For any temperature below the reorientational phase transition there exists a critical perpendicular-to-plane magnetic field, which separates multidomain and monodomain states of the film. The theory explains recent experimental observations.