Two-Dimensional Model for a Domain Wall

Abstract

The magnetization vector in a conventional Néel wall between ferromagnetic domains is modified by a sinusoidal variation along the film thickness. Outside a small ``kernel'' region, the volume charge is cancelled by an appropriate choice of the second component of the magnetization vector (along the film thickness), while the surface charge vanishes everywhere along the wall. This configuration yields a wall energy which is somewhat smaller than the energy calculated by Brown and LaBonte as an absolute minimum of all one‐dimensional wall configurations, at least in the thickness of 10³ to 10⁴ Å in Permalloy. Since this is the thickness range in which the so called Bloch walls are usually observed experimentally, it seems that these walls do not have the one‐dimensional structure that is assigned to them, which can at most take place in bulk materials. For thickness of Permalloy much larger than 10⁴ Å, the energy of the new wall becomes larger than that of the conventional Bloch wall, and eventually it tends to infinity for an infinite film thickness.