Magnetic Properties of Ring-Shaped Composite Anisotropy Multilayers

We have investigated eight-layered and twelve-layered composite anisotropic films to obtain advanced properties for practical use, and to understand the relation between the magnetic layers. Calculations of the permeability based on the Landau-Lifshitz relation predict that the dipole-dipole coupling between the magnetic layers works in favor of the Ku (in-plane uniaxial anisotropy) in each magnetic layer. When the gap between the magnetic layers is varied using ceramic layers, the dipole moment of the metal layers is influenced by the magnetic interaction of a ripple stray field in a 45° direction across intervening ceramic layers. In order to clarify the mechanism governing the isotropic permeabilities of these multilayer films, we extended our study to include ring-shaped as well as disk-shaped samples. In comparison with a uniaxial multilayer film, a ring-shaped composite anisotropy multilayer film has a closed magnetic circuit and hence a large inductance. Composite anisotropy effects are discussed.