Dependence of loss on domain-wall spacing in polycrystalline material

Measurements of total power loss and domain-wall spacing have been made on individual grains in polycrystalline specimens of commercial grain-oriented 3% silicon-iron material. The loss per cycle versus frequency characteristic of a grain is found to consist of discrete linear portions, as distinct from the continuous function that has often been reported. These linear portions are found to correspond to different domain configurations. The loss per cycle is shown to be proportional to the domain-wall spacing, which is observed to decrease with increasing frequency.