Magnetic excitations of interface pinned domains

We study the uniform excitations of the domains of a thin magnetic film on a two sublattice antiferromagnetic substrate. An interface step defect stabilizes a domain wall which holds two large ferromagnetic domains with opposite magnetization on each side of the defect line. The orientation of the magnetization in the domains, in response to an external field, parallel to the film surface, differs from the single domain situation and leads to new dispersion relations for the uniform precession modes of the ferromagnetic film. We apply the model to the case of a Neel wall of a uniaxial ferromagnetic film and discuss the implications of the results in measurements of the interface effective exchange field.