Giant magneto-impedance effect in CoMnSiB amorphous microwires

The giant magneto-impedance (GMI) ratio, DeltaZ/Z = [(Z(H) - Z(H-max)]/Z(H- max), in a nearly zero magnetostrictive Co68.5Mn6.5Si10B15 amorphous microw ire has been investigated for the frequency range 0.5-10 MHz, driving curre nt 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, H-m, corre sponding to the maximum DeltaZ/Z ratio allows to estimate the magnetostrict ion constant (lambda (s) approximate to - 2 x 10(-7)) to be in good agreeme nt with lambda (s) values estimated by different methods and in amorphous a lloys with similar compositions. (C) 2001 Elsevier Science B.V. All rights reserved.