  A combination of experimental techniques, e.g. vector-MOKE magnetometry, Kerr
microscopy and polarized neutron reflectometry, was applied to study the field
induced evolution of the magnetization distribution over a periodic pattern of
alternating exchange bias stripes. The lateral structure is imprinted into a
continuous ferromagnetic/antiferromagnetic exchange-bias bi-layer via laterally
selective exposure to He-ion irradiation in an applied field. This creates an
alternating frozen-in interfacial exchange bias field competing with the
external field in the course of the re-magnetization. It was found that in a
magnetic field applied at an angle with respect to the exchange bias axis
parallel to the stripes the re-magnetization process proceeds via a variety of
different stages. They include coherent rotation of magnetization towards the
exchange bias axis, precipitation of small random (ripple) domains, formation
of a stripe-like alternation of the magnetization, and development of a state
in which the magnetization forms large hyper-domains comprising a number of
stripes. Each of those magnetic states is quantitatively characterized via the
comprehensive analysis of data on specular and off-specular polarized neutron
reflectivity. The results are discussed within a phenomenological model
containing a few parameters which can readily be controlled by designing
systems with a desired configuration of magnetic moments of micro- and
nano-elements.
