Correlation Between Magnetic Anisotropy and Permeabiiity of Amorphous Multi-Layered Films

The permeability of amorphous single- and multilayered films was studied. As the uniaxial anisotropy becomes smaller, the permeability along the hard axis increases at low frequencies but decreases at high frequencies. The domain structure of layered films becomes simple with decreasing layer thickness, and such films have high permeability (≫ 10,000) and good frequency characteristics. However, for films with large Hk (¿1.3 Oe), the permeability does not show a clear structure dependence. A simple calculation based on the Landau-Lifshitz model shows that the rotational permeability at high frequencies deteriorates when the magnetization direction deviates from the easy axis. It was found that films having both high permeability and good frequency characteristics can be obtained by optimizing the multilayered structure.