Magneto-optical imaging has revealed new features crucial for the understanding of the exchange bias phenomenon. We have observed hybrid domain walls consisting of ferromagnetic (FM) and antiferromagnetic sections and their evolution. The external magnetic field moves only the ferromagnetic section of the hybrid domain walls, leading to the formation of an exchange spring parallel to the interface. The nucleation and unwinding of the exchange spring occur at different locations and its propagation depends on the chirality of the FM domain walls. The stationary antiferromagnetic sections of the hybrid domain walls define the antiferromagnetic domains.

• Received 12 August 2002

DOI:https://doi.org/10.1103/PhysRevB.68.014418