Controlled domain wall motion in micron-scale permalloy square rings

Domain configurations and magnetization reversal processes of two-micron size permalloy square rings are investigated. We demonstrate that such rings display a few distinct domain structures that can be transformed into each other via controlled domain wall displacement. In order to selectively control the movement of separate domain walls, we fabricated rectangular dots adjacent to the ring structure. We show that the magnetic field originating from these dots determines the evolution of the domain configurations.