The simulation of domain wall motion in square loop ferrites, and other aspects of wall behaviour

It is shown that existing one-dimensional models of wall motion, whether conservative or non-conservative in form, do not account for all aspects of the reversal process and to some extent contradict each other. These difficulties are resolved by a two-dimensional model with which the behaviour of a 180° domain wall in a square grain is investigated. The wall is free to flex and interact with obstacles, e.g. pores, placed at random on the points of a square lattice which is generally incompletely populated. The motion of the wall under various conditions is simulated with a digital computer. The effect of changing the porosity, grain size and magnetocrystalline anisotropy can be investigated, and is applied to the shape of the hysteresis loop, the minor loops associated with delta noise and the relationship between wall velocity and applied field. The effect of a change in wall area during the reversal process is also discussed.