  The potential experienced by transverse domain walls (TDWs) in the vicinity
of asymmetric constrictions or protrusions in thin Permalloy nanowires is
probed using spatially resolved magneto-optical Kerr effect measurements. Both
types of traps are found to act as pinning centers for DWs. The strength of
pinning is found to depend on the trap type as well as on the chirality of the
incoming DW; both types of traps are seen to act either as potential wells or
potential barriers, also depending on the chirality of the DW. Micromagnetic
simulations have been performed that are in good qualitative agreement with the
experimental results.
