Domain Observations on Iron Whiskers

We have confirmed the appearance in iron whiskers of domain walls which apparently violate the restriction that the normal component of magnetization must remain constant across the wall. These walls sometimes have a dotted or serrated appearance. We have found such walls in a closure domain structure which permits the calculation of an approximate value for the surface energy of the serrated wall; this energy is approximately ten times the energy of a normal 90° wall or five times the energy of a normal 180° wall. We conclude that the serrated wall contains an inner structure which largely eliminates any free poles.