Recent advances in studies of magnetically soft amorphous microwires

In this paper, we present the giant magneto-impedance (GMI) effect (real part of longitudinal impedance, Z, and of the off-diagonal impedance) and hysteretic magnetic properties of amorphous glass-coated microwires with different compositions possessing nearly zero, positive and negative magnetostriction constant and metallic nucleus diameter ranging between 6 and 16 μm. Enhanced soft magnetic properties (low coercivity of about 4 A/m) and high-GMI effect have been observed in Co-rich microwires with vanishing magnetostriction constant. The magnetic anisotropy field of these microwires depends on the ratio between metallic diameter, d and total microwires diameter, D. Stress-sensitive magnetic properties have been obtained in Fe-rich microwires after stress annealing: hysteresis loop stress-annealed (SA) microwires drastically changes under applied stress. A variety of hysteresis loops with different hysteresis loops can be obtained in Fe-rich microwires changing the conditions (time and/or temperature) of the stress annealing. The obtained results allow us to tailor the microwire magnetic properties for magnetic sensors applications through selection of their composition and/or geometry and by thermal treatment.