Magnetization Distribution of 180° Domain Walls at Fe(100) Single-Crystal Surfaces

We present the first experimental analysis of domain-wall fine structure at the surface of single-crystal iron bulk material by means of a UHV microscope with spin-polarization analysis of the secondary electrons. It is found on Fe(100) that the domain wall of a 180^∘{} Bloch wall in the bulk is terminated in a N\'eel-type structure at the surface. In spite of this dramatic change of the wall structure, the wall width at the surface is about the same as inside the sample. For the 180^∘{} Bloch walls we find a width of 210±{}40 nm.