MAGNETIC FINE-STRUCTURE OF DOMAIN-WALLS IN IRON FILMS OBSERVED WITH A MAGNETIC FORCE MICROSCOPE

The submicron magnetic structure of domain walls in a single-crystal iron film has been studied using a magnetic force microscope (MFM). The MFM tip was sensitized to the component of the field perpendicular to the film plane. The sample examined was a 500-nm-thick single-crystal film of iron, grown by molecular-beam epitaxy (MBE). Before it was imaged, the film was magnetized along its (in-plane) easy axis in a 2000-Oe field. Studies of the domain structure at numerous locations on the film surface revealed a rich variety of micromagnetic phenomena. Parallel domain walls, determined to be Bloch walls with a width of 70-100 nm, were seen along the easy axis, spaced roughly 30 mum apart. These appeared to be Bloch walls. Bloch lines were also observed in the walls with an average periodicity of 1.5 mum. This is a value smaller than that predicted for Bloch wall-line structures. In addition, a pronounced zig-zag structure was observed, as expected from previous Fe whisker observations.