Complementary Magneto-Impedance Effect in Quenched Amorphous Wire.

Abstract

A new sensitive magneto-impedance (MI) effect was found in quenched FeCoSiB amorphous wire of 30 μm diameter, in which the wire impedance steeply increases from around the dc resistance value to a value almost three times higher with increase in the external applied field Hex, even at a low frequency. The new Ml effect shows application of Hex from the non-skin-effect case due to its large coercivity Hc (about 1.5 Oe), at which the circumferential permeability μθ is so small that the skin depth δ( = 2ρ/ωμθ)1/2)is larger than the wire radius a, to the skin effect case with steep decrease of Hc (a steep increase of μθ) for Hex applied vertical to the circumferential domain wall. On the other hand, the MI sensitivity in the quenched amorphous wire is low for a magnetizing current of dc-biased ac, because of its high magnetic anisotropy field Hk of about 3 Oe due to the nonexistence of domain walls.