Studies of High-Frequency Giant Magnetoimpedance Effect in Co-Rich Amorphous Microwires

We studied giant magnetoimpedance (GMI) effect and magnetic properties of various Co-rich amorphous microwires. We measured the values of magnetic field dependence of the GMI ratio up to gigahertz frequency range, and observed quite high GMI ratio in as-prepared Co-rich microwires even at gigahertz frequencies. We observed the different values of the magnetic anisotropy field obtained from the hysteresis loops and the impedance curves. Observed dependence can be explained considering different magnetic anisotropy in the surface layers and in the inner part of metallic nucleus and skin depth effect. Features of high-frequency GMI effect have been analyzed using ferromagnetic resonance-like approximation.