Effect of tensile stress on the field response of impedance in low magnetostriction amorphous wires

The influence of magnetoelastic anisotropy on the giant magneto-impedance (GMI) effect is studied for positive and negative magnetostriction amorphous wires of compositions Fe4.9Co71.8Nb0.8Si7.5B15 and Co68.1Fe4.4Si12.5B15, respectively, A careful investigation of the impedance as a function of applied magnetic field and tensile stress is presented for two different frequencies (f = 5 kHz and f = 100 kHz) of the driving current. Clear maxima develop in both the resistive and reactive components of the impedance, which shift towards larger fields (in the vicinity of the anisotropy field) as the magnetoelastic anisotropy is increased. Some distinctive aspects found in the field behavior of both in-phase and quadrature components reflect the complexity of the GMI effect, which depends on the field dependence of the circular magnetic permeability, A detailed discussion about the stress dependence of the basic magnetization processes and their influence in the impedance response is presented.