The effect of annealing on magnetic properties of "Thick" microwires.

In this paper we provide results on effect of post-processing on magnetic properties (giant magnetoimpedance, GMI, effect and domain wall dynamics) of Fe 71.7 B 13.4 Si 11 Nb 3 Ni 0.9 glass-coated microwire with metallic nucleus diameter d = 103 μm and total diameter D = 158 μm prepared by Taylor-Ulitovsky method. Amorphous structure of as-prepared wires is confirmed by X-ray diffraction and electronic microscopy. As-prepared glass-coated wires present relatively low GMI ratio (about 50% at 500 MHz) and relatively low coercivity (about 25 A/m). Additionally, as-prepared sample present rectangular hysteresis loop and fast single domain wall propagation with domain wall mobility of about 11,9 m2/As. After annealing (either under tensile stress or without stress) we observed considerable improvement of the GMI ratio (from 50% up to 220% at 200 MHz) and domain wall mobility up to 15,5 m2/As. Observed GMI effect and domain wall mobility improvement has been attributed to the stresses relaxation and creep anisotropy. We demonstrated that the Taylor-Ulitovsky technique is suitable for preparation of "thick" Fe based amorphous microwires with good magnetic properties and GMI effect suitable for industrial applications. Image 1 • Preparation of thick glass-coated amorphous microwires. • Improvement of GMI effect of microwires by -annealing. • Fast single domain wall propagation with domain wall mobility of about 11,9 m2/As. • Enhancement of domain wall propagation by annealing. • Change of Hysteresis loop of microwires from rectangular to linear after stress annealing. • Enhanced GMI ratio of thick microwires in a wide frequency range. [ABSTRACT FROM AUTHOR]