FeCoNi Electroplated Wire Based Magnetoimpedance Sensitive Element

The CuBe/Fe20Co6Ni74 composite wires for magneto-impedance (MI) sensors were prepared by electrodeposition of 1 mu m thick FeCoNi magnetic layer onto a non-magnetic substrate. Longitudinal magnetic anisotropy was induced by 1 hour annealing in a dc magnetic field of 20 Oe at a temperature of 320 degrees C Angular dependencies of MI were measured in a frequency range of 0.6 to 1 MHz for driving current intensities of 2.5 to 20 mA. Very high longitudinal MI of the order of 400% was observed at a frequency of 1 MHz. The highest value of the sensitivity of 520%/Oe with respect to applied field was observed for the active resistance Delta R/R component. Very high and linear sensitivities of 0.0023 Omega/degrees, 0.023 Omega/degrees, 0.05 Omega/degrees were observed for the fields of 1.5, 3.0 and 3.5 Oe respectively for low angles, where MI sensors with flat geometry are less effective.