Transition between Bloch and Néel Walls

Abstract

The transition between Néel and Bloch walls is shown to be gradual rather than abrupt, resulting in a wall with Néel and Bloch components superposed. For films thick enough so that such a transition can occur, the wall is a pure Néel wall if φf, the acute angle between the wall normal in the plane of the film and the magnetization at the edge of the wall (half the angle between the magnetization vectors in the two domains separated by the wall) is less than a critical value. For φf larger than that critical value but less than π/2, the wall contains both Néel and Bloch components. When φf is π/2, i.e., a 180° wall, the wall is of the pure Bloch type; however, this situation is often unstable, resulting in a transition wall with the Néel component reversing periodically in distance along the wall in a crosstie-like structure. These conclusions are supported by Lorentz micrographs.