Excitations of domain walls pinned at F/AF interface steps

We study rigid displacement excitations of a Neel wall of a thin uniaxial ferromagnetic film on a two-sublattice antiferromagnetic substrate. An interface step defect pins the domain wall and provides the restoring force that stabilizes the domain wall oscillations. The frequency of the rigid displacement domain wall modes is shown to be of the same order of magnitude as that of the uniform domain modes of the ferromagnetic film, for a wide range of interface exchange energy values.