Domain wall generation and propagation in an amorphous ferromagnetic NiFeSiB film confirmed by the magneto-optical indicator film method

We employed the magneto-optical indicator film method to observe domain wall generation and propagation in NiFeSiB thin films. This method is sensitive to the magnetization directions on both surfaces as well as in the interior of the film. NiFeSiB has a lower magnetic anisotropy value compared to that of the CoFe and, therefore, it contains thicker domains. As an external magnetic field is strengthened, an increasing number of domains are generated and propagated into the interior. The use of a synthetic antiferromagnet layered structure leads to a reduction in both the value of the switching field and the number of domains generated as compared with the NiFeSiB single layer case, resulting from a reduction in the magnetostatic energy.