Direct observation of changes to domain wall structures in magnetic nanowires of varying width

Lorentz microscopy has been used to explore the structure variation of domain walls in thin Permalloy nanowires in the vicinity of symmetric triangular antinotches. The antinotches present a complex potential landscape to domain walls. Walls can be trapped in front of, partly enter, or be trapped inside the antinotches according to the geometry of the latter and, in the case of vortex domain walls, the chirality. In all cases, the magnetization distribution was determined. Of particular note was the structure the wall assumed during depinning from the antinotch, complex forms extending over distances several times the wire width being observed.