Magnetization reversal of ferromagnetic layer in exchange coupled Mn-Ir/Co-Fe epitaxial bilayers

The magnetization reversal process for Mn-Ir/Co-Fe epitaxial bilayers was investigated using magneto-optical Kerr microscopy. It was found that the magnetization reversal of the ferromagnetic layer progresses in different ways when the crystallographic orientation of the bilayers is changed. In the (1 1 0) bilayers, 180° domain walls sweep over the whole film plane to reverse the magnetization of the ferromagnetic layer. On the other hand, in (0 0 1) bilayers, smaller domains nucleated homogeneously in the film plane combine with each other around the coercive fields and saturate the magnetization.