Shape Anisotropy in Magneto-Impedance NiFe-Based Microsensors

Abstract

The magneto-impedance response of narrow multilayered NiFe/Cu/NiFe structures realized by micromolding has been characterized as a function of both the excitation frequency and the magnetic field. It has been found that intrinsic magnetic properties do not depend on the ferromagnetic geometry, but properties related to the applied magnetic field, i.e. anisotropy field and magneto-impedance value do. The results are consistent with numerical simulations and show that the anisotropy field varies with the ferromagnetic film thickness. The highest magneto-impedance variation and anisotropy field, 170 % and 4200 A/m were found for the narrowest and thickest structure.