Abstract

The ratio and sensitivity of giant magnetoimpedance (GMI) in grain oriented silicon steels (Fe-4.5%Si) are improved after furnace annealing in air for 20 min. By annealing at 800°C, the GMI sensitivity rises from 1.29%/Oe to 1.91%/Oe and the ratio increases from 237% to 294% with decreasing characteristic frequency. The results are attributable to an increase in the transverse magnetic permeability during the heat treatment. From simulation by finite element method, the GMI effect can be interpreted as the modification of the current distribution by the applied magnetic field via the transverse permeability. In the case of annealed samples, the larger transverse permeability allows a higher GMI ratio and sensitivity. © 2009 by The Editorial Board of Journal of Materials Science & Technology, Shenyang, China. All rights reserved.