Magnetic Domain Patternsin Bilayered Ribbons Studied by Magnetic Force Microscopy and Magneto-Optical Kerr Microscopy

The magnetic domain patterns of amorphous bilayered FeSiB/FeNbSiB and FeNbCuSiB/CoSiB ribbons are observed and analysedusing the magneto-optical Kerr microscopy (MOKM) and magnetic force microscopy (MFM). Both microscopic techniques arehighly sensitive to the sample surface; possibility of Kerr microscopy to visualize the domains separately in both layers is achievedby focusing the laser spot on the ribbon cross section. Wide curved domains as well as fine fingerprint domains were detected atthe surface of ribbons due to presence of local stresses coming from the preparation process. With respect to high lateral resolutionof MFM and its out-of-plane magnetization sensitivity, the perpendicularly magnetized crossed stripe domain patterns can beselected as well. Coiling of the ribbons on the half-round-end sample holder is often used to induce and control the magneticanisotropy of these alloys. Changes in the magnetic domain structure at the outer-coiled surface and its dependence on the sign ofmagnetostriction coefficient are discussed in detail. Finally, the MFM images in the presence of external in-plane magnetic field upto±40 kA/m are shown.