  In antiferromagnetically coupled multilayers with perpendicular anisotropy
unusual multidomain textures can be stabilized due to a close competition
between long-range demagnetization fields and short-range interlayer exchange
coupling.
  In particular, the formation and evolution of specific topologically stable
planar defects within the antiferromagnetic ground state, i.e. wall-like
structures with a ferromagnetic configuration extended over a finite width,
explain configurational hysteresis phenomena recently observed in
[Co/Pt(Pd)]/Ru and [Co/Pt]/NiO multilayers.
  Within a phenomenological theory, we have analytically derived the
equilibrium sizes of these "ferroband" defects as functions of the
antiferromagnetic exchange, a bias magnetic field, and geometrical parameters
of the multilayers. In the magnetic phase diagram, the existence region of the
ferrobands mediates between the regions of patterns with sharp
antiferromagnetic domain walls and regular arrays of ferromagnetic stripes.
  The theoretical results are supported by magnetic force microscopy images of
the remanent states observed in [Co/Pt]/Ru.
