Investigation of some complex BH-loop characteristics of thin Permalloy films using Kerr-effect microscopy

A variety of Permalloy thin films were prepared under various sputtering conditions, producing BH loops exhibiting diverse magnetic characteristics. The domain structures of these films was observed with Kerr-effect microscopy using high-speed image processing (video). The specimens were in the thickness range of 800 to 1600 Å and had square dimensions of 100 μm. It was observed that BH loops showing strong uniaxial magnetic orientation correspond to films with properly oriented domains. However, Permalloy films which exhibit poor uniaxial anisotropy may contain distinct regions of different magnetic orientation or islands of weak anisotropy within a predominantly uniaxial domain structure. The BH-loop characteristics and coercivities are discussed in light of the optical findings