Magnetostatic effects in grain-oriented silicon iron

The function of the free-surface poles appearing on oriented silicon-iron strips in controlling the domain structure is discussed. The energy of a simple 180° domain structure is given as a function of the dimensions, angle of dip, and applied field; this model is shown to give high values of the magnetostatic energy for angles of misorientation greater than 2°. On general theoretical grounds, the proportion of 90° domains is calculated as a function of the misorientation and is shown to agree with experiment. A detailed model of the 90° domain structure is discussed; its magnetostatic energy is estimated and predictions of the equilibrium domain size are in reasonable agreement with observation.