Giant magneto-impedance effect in CoMnSiB amorphous microwires

The giant magneto-impedance (GMI) ratio, ΔZ/Z=[(Z(H)-Z(Hmax)]/Z(Hmax), in a nearly zero magnetostrictive Co68.5Mn6.5Si10B15 amorphous microwire has been investigated for the frequency range 0.5-10 MHz, driving current amplitude of 0.5-2.5 mA, bias DC magnetic field up to 2400 A/m and under applied tensile stress up to 132 MPa. A maximum relative change in the GMI ratio up to around 130% is observed at a frequency of 10 MHz, magnetic DC field of about 180 A/m, driving current amplitude of 1 mA and under tension of 60 MPa. The tensile stress dependence of the magnetic field, Hm, corresponding to the maximum ΔZ/Z ratio allows to estimate the magnetostriction constant (λs∼-2x10-7) to be in good agreement with λs values estimated by different methods and in amorphous alloys with similar compositions