The dependence of power loss on domain wall bowing in single crystals of 3% grain-oriented silicon-iron

In a previous paper it has been reported that the domain wall motion and localized power loss have been measured for single crystals of 3% grain-oriented silicon-iron. Domain wall pinning points, in the form of scratches or holes, were then introduced into the specimens. This resulted in an increase in the total power loss since some walls are retarded but the majority move at an increased average wall velocity and there is also an increase in the amount of wall bowing occurring. In this paper, a comparison is made of the increase in the measured power loss and the change in the theoretical power loss based on the change in domain wall motion, in particular domain wall bowing, caused by the introduction of pinning points. Assuming a parabolic wall profile values of the average of the peak displacement squared, <x²>, have been calculated for an increase in the amount of wall bowing while maintaining the same flux density. As the amount of bowing increases the value of <x²> increases which results in an increase in the loss calculated by the theoretical model. Good correlation is obtained between this theoretically calculated increase in power loss and the increase in power loss measured experimentally.