Surface magnetic domain observation on thin-gauged 3% Si-Fe sheets by using scanning electron microscopy with polarization analysis (SEMPA)

The 100 μm thick 3%Si-Fe sheets, which have magnetic induction at 10Oe (B10) of 1.57 to 1.98 Tesla, were prepared through induction melting, hot and cold rolling, and vacuum annealing processes. Scanning Electron Microscopy with Polarization Analysis (SEMPA) was used to image the surface magnetic domain structure of the 3% Si-Fe sheets in ultra-high vacuum. Two orthogonal in-plane components of the spin polarization of the secondary electrons were measured to obtain the magnetic domain images. It was observed by using SEMPA that the B10 = 1.98 Tesla sample was almost composed of 180 ° stripe domains which are parallel to the rolling direction. On the other hand, the Si-Fe sheet with B10 = 1.57 Tesla is composed of large 180 ° stripe domains that are slanted about 30 ° to the rolling direction. In addition, complex magnetic domain structures like tree and zigzag patterns were observed on the 1.57 Tesla sample surface.