GMI effect in amorphous glass covered microwires as a function of the internal induced stresses

The influence of the microwires diameter on the GMI effect, which consists of a significant change in the impedance of a piece of soft magnetic material driven by a high-frequency current when it is introduced into a static magnetic field, in CoFeSiB nearly zero magnetostrictive glass covered wires is presented. The largest GMI effect is obtained for microwires having the metallic core diameter of about 20 mu m. The experimental results are discussed considering the calculated magnetic anisotropies induced by mechanical stresses. The GMI dependence on the longitudinal magnetic field is changing both the shape, from a double peak-like to a single-peak like curve, and the magnitude. The suitable combination metallic core diameter-glass cover thickness results, over the control of the internal stresses distribution, into an optimum GMI response.