Theoretical considerations of magnetostriction in silicon iron

The magnetostriction of well oriented silicon iron is discussed on the basis of a simple domain model containing only 180° domains. The effect of an externally applied magnetic field on the domain configuration is examined on an energy basis, which indicates that the magnetostatic energy is the principal factor involved and that rotation of the domain magnetisation vector can occur at low field strengths. It is further shown that such rotation gives rise to negative magnetostriction. The possible effects on the observed magnetostriction of a few badly oriented crystals in a polycrystalline specimen are also discussed.