Adjustable Microwave Properties in FeCoZr/Cu Multilayers

The FeCoZr/Cu multilayers were prepared by radio frequency sputtering. The static and microwave properties of these films were investigated by measuring the hysteresis loops and microwave permeability spectra. According to the static magnetic results, the multilayers were well in-plane uniaxial anisotropic samples with high saturation magnetization 1.7 T. The anisotropic field of these multilayer thin films can be adjusted from 18 Oe to 64 Oe by changing the thickness of Cu interlayer from 8.7 nm to 1.8 nm. As a consequence, the microwave permeability and resonance frequency can also be adjusted from 1.70 GHz to 2.88 GHz. This work might facilitate search for new materials with high permeability at high frequency.