Control of Domain Wall Motion in Permalloy Ring

Domain wall motion through current-induced Oersted field was investigated by magnetic force microscopy, magnetoresistance measurement, and micromagnetic simulation. Microstructured permalloy rings with nonmagnetic control leads were fabricated by means of electron beam lithography. Through variant arrangement of control lead, the generation of uniform and nonuniform Oersted fields on a single element becomes achievable. The movement of the walls within vortex-pair state, clockwise or counterclockwise, was controlled by the Oersted fields