Double-layered films made of CoNbZr films with SiO2 interlayers were prepared and their high-frequency characteristics were investigated to optimize the dimensions of the film for micromagnetic devices used in the high-frequency range around 100 MHz. The dependence of the magnetic state, that is, the easy-axis state and closure-domain state of the striped film, on the film thickness is similar to that shown in the theoretical phase diagram by Slonczewsky et al. The appropriate thickness of interlayers for maximizing the ratio μ′/μ″ depends on the magnetic film thickness and film width in the region of the easy-axis state. The ratio μ′/μ″ varies with the film width and length. These results show that films with relatively high permeability and low film loss are obtained by optimizing the interlayer thickness, film width, and length.
