Changes in the magnetostriction characteristics of grain-oriented electrical steels due to laser irradiation were studied. It was found that the ac magnetostriction amplitude could be controlled by laser irradiation, which creates magnetic closure domains in the steels. This effect may make it possible to reduce the transformer noise.
Whereas the volume of lancet-type sub-domains increases with the magnetization in the domain wall displacement processes, that of the closure domains caused by laser irradiation decreases. When the effects of these two types of domains on the sample length are controlled so that they equal each other, a low ac magnetostriction amplitude can be obtained.