  In superconducting ferromagnets the equilibrium domain structure is absent in
the Meissner state, but appears in the spontaneous vortex phase (the mixed
state in zero external magnetic field), though with a period, which can
essentially exceed that in normal ferromagnets. Metastable domain walls are
possible even in the Meissner state. The domain walls create magnetostatic
fields near the sample surface, which can be used for experimental detection of
domain walls.
