Excitations of domain walls pinned at F/AF interface steps

Summary form only given. The magnetic properties of thiii ferromagnetic (F) films grown on antiferromagnetic (AF) substrates may be controlled to a large extent by the nature of the interface. Interface roughness in F/AF bilayers is a subject of current interest and despite the research effort dedicated to the subject and the large amount of experimental data accumulated so far, there are still unsolved questions. In this contribution we show that the step defect may produce strong reduction of the domain wall width and that the frequency of rigid displacement domain wall oscillations is determined by the interface exchange energy within the domain wall region. We consider a Neel wall of a thin uniaxial ferromagnetic film on a two-sublattice AF substrate. The uniaxial direction of the substrate is supposed to coincide with the easy axis direction (z-axis) of the ferromagnet. The normal to the surface is along the y-axis and a step, running along the z-direction, divides the substrate into two regions, each containing spins from opposite sublattices of antiferromagnet.