Modeling the Giant Magnetoimpedance Effect in Amorphous Microwires with Induced Magnetic Anisotropy

The giant magnetoimpedance effect in a glass-coated Fe-based amorphous microwire annealed under stresses is theoretically studied. The magnetization distribution in a microwire is described within a model that takes into account the presence in the sample of two regions with different types of magnetic anisotropy. It is assumed that, in the central part of the microwire, the anisotropy is longitudinal and, in the surface region, an induced helicoidal anisotropy arises as a result of annealing. An expression for the impedance of the microwire with allowance for different permeabilities of the two regions is found. The obtained theoretical dependences of the impedance on an external field and frequency make it possible to qualitatively describe the results of experimental studies of the magnetoimpedance in glass-coated Fe-based amorphous microwires.