GMI effect in ultra-thin glass-coated Co-rich amorphous wires

In this paper we report novel results on the GMI effect at frequencies between 10 MHz and 500 MHz in ultra-thin Co–Fe-rich amorphous glass-coated microwires with nearly zero magnetostriction constant with metallic nucleus diameter of about 8.5 μm. MHz the GMI of thin microwires is smaller than in thicker conventional wires and glass-coated microwires, but increasing the frequency GMI effect significantly increases, exhibiting much higher GMI effect at high frequencies and the shape of the dc magnetic field dependence of the GMI ratio is typical for the materials with circular magnetic anisotropy, i.e. with the a maximum at certain dc axial magnetic field. s, the glass-coating technology gives rise to the internal stresses due to the difference in the thermal expansion coefficients of the glass coating and metallic nucleus. This difference in the fabrication technique results in the different magnetic anisotropy in the surface and in different frequency dependence of the GMI effect.