Internal Magnetic Domain Structure of Domain-Refined Grain-Oriented Electrical Steel Sheet

The internal magnetic domain structures near the laser irradiation area in a grain-oriented electrical steel sheet were observed by a magnetic microscope utilizing the magnetooptical effect called x-ray magnetic circularly polarized emission, in order to understand the magnetostriction characteristics of grain-oriented electrical steel. In the dc magnetized state, the domain structures consisted of main domains that were separated by 180° domain walls and closure domains. The magnetization component perpendicular to the sheet plane were observed in the regions adjacent to the main domains. The observed closure domains directly below the laser irradiation area showed magnetization component perpendicular to the sheet plane and elongated along the normal direction. The width of closure domains in the internal layer was wider than that in the surface layer of the steel sheet.