Enhanced Giant Magnetoimpedance Effect in Rapid Heat-Treated Fe-Based Amorphous Ribbons

An enhanced giant magnetoimpedance (GMI) effect of Fe-based amorphous ribbons is obtained by rapid heat treatment. The structural investigations on the ribbon reveal the presence of two phases, i.e. a fine grained Fe₃Si phase and a residual amorphous phase on rapid heat treatment. The soft magnetic property is improved by rapid heat treatment; the crystal size and grain size of Fe₃Si decrease. The maximum magnetoimpedance ratio obtained in the present study is 81% at 10 MHz, and the optimized heat-treated rate is 200°C/min. Separated GMI curves are observed after the simultaneous rapid heat treatment and magnetic field annealing. This suggests that tailoring of the nanocrystalline microstructures induced by optimum rapid heat treatment conditions can result in an excellent GMI effect.