Domain structure in magnetic films with a saturation magnetization higher than the anisotropy field

The domain structure (DS) of yttrium-iron garnet films with uniaxial anisotropy fields higher than ∼120 Oe was found to have a 3D character: there is a stripe domain structure of a certain type in the surface layer and a structure of another type in the film bulk. It was revealed that in the absence of an external magnetic field, the boundaries of both DSs are almost perpendicular, whereas with an increase in an external field applied in the film plane along the boundaries of the interior-volume DS, the boundaries of the surface DS are gradually reoriented along the external field. This phenomenon is theoretically explained on the basis of the micromagnetic model, which describes DS formation in ferrite films.