One-dimensional zero-degree double bloch walls in thin films

Abstract

The magnetization M (x) in a ferromagnetic film is approximated by a discrete distribution for which the magnetostatic energy can be calculated exactly, without restrictions on the functional form of M (x). The minimum internal energy (exchange, anisotropy, and magnetostatic) and related magnetization distribution for two parallel Bloch walls with opposite senses of rotation are computed for various fixed spacings between the wall centers. The two walls repel one another because of their magnetic interaction. As a consequence, an energy barrier separates the energetically more favorable state of uniform magnetization from the stable 0°double Bloch wall configuration. The results show that the energy at the peak of the barrier is about 12.5% above the energy of two corresponding isolated 180°walls. The applied field necessary to maintain an equilibrium distribution for a given wall spacing is calculated as a function of the wall separation. It is found that a field of at least H0=0.204 Ms (163 Oe if Ms=800 emu) is required to overcome the energy barrier and collapse the distribution to a state of uniform magnetization. © 1966 The American Institute of Physics.