Magnetization reversal and magnetic domain structures controlled by the magnetostatically induced stray field in perpendicular antiferromagnetically coupled [Pd/Co]_7/Ru/Co/[Pd/Co]_7 multilayer were investigated by magnetic force microscopy. For the sample demagnetized in plane, field-induced ferromagnetic domains at the boundary of antiferromagnetic domains provide the nucleation channel. The ferromagnetic domains in the channel are parallel aligned along the applied field out of plane firstly, and then the magnetization reversal is dominated by the propagation of the ferromagnetic channels toward the region of antiferromagnetic domains. The sample demagnetized in perpendicular direction shows antiferromagnetic coupling state. Ultraslow reversal dynamics were observed under a perpendicular critical magnetic field (H_(cri)) in a long time. The reversal process can be explained by the inhomogeneous local stray field and the competition between magnetostatic energy and exchange energy.
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