Influence of magnetostriction on high-frequency magnetotransport properties of current-annealed amorphous magnetic wires

Selected samples with different magnetostriction constants λs have been submitted to current annealing (dc Joule heating) to relax internal stresses produced during fabrication and to induce circular anisotropy. High-frequency (30 MHz–6 GHz) giant magneto-impedance has been measured with a vectorial network analyzer. The variation of the characteristic impedance with the magnetic field turns out to be a function of the thermal treatment and of the alloyʹs λs. In general, the magneto-impedance response is seen to be slightly improved by thermal treatments at low-frequency values.