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In antiferromagnetically coupled superlattices a close competition between long-range dipole interaction and short-range interlayer exchange coupling causes a formation of unusual domain textures. These wall-like structures can be viewed as a net of specific topologically stable planar defects. Within a phenomenological theory we have classified and analyzed the possible magnetic defects, determined their structures and region of existence for each of them with respect to geometrical and material parameters of superlattices. The theoretical results are confirmed by direct observation of the remanent states in [Co/Pt]/Ru multilayers with the aid of magnetic force microscopy. We also discuss in detail field driven evolution of different types of topological defects which explain configurational hysteresis phenomena recently observed in [Co/Pt(Pd)]/Ru(Ir,NiO) multilayers. |
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