Optimization of soft magnetic properties in nanocrystalline glass-coated microwires

Abstract

We have studied correlation of magnetic properties, structure and Giant Magnetoimpedance (GMI) effect, of Finemet-type FeCuNbSiB microwires. We have observed that GMI effect and magnetic softness of glass-coated microwires produced by the Taylor-Ulitovski technique can be tailored either controlling magnetoelastic anisotropy of as-prepared FeCuNbSiB microwires or controlling their structure by heat treatment. We have observed considerable magnetic softening of studied microwires after annealing. This magnetic softening correlates with the devitrification of amorphous samples. Amorphous Fe-rich microwires exhibit low GMI effect (GMI ratio below 1%). Considerable enhancement of the GMI effect (GMI ratio up to 90%) has been observed in heat treated microwires with nanocrystalline structure. We believe that FINEMET-type glass-coated microwires with higher saturation magnetization are good candidates for GMI sensor and metacomposites applications.