Low-field microwave absorption and magnetoimpedance in glass-coated and uncoated CoFeBSI microwires

Microwave absorption measurements were carried out on glass-uncoated amorphous microwires of 24, 12, and 7 mu m in metallic core diameter. LFA spectra show a maximum and minimum on the magnetic field cycle sweep, indicating an anisotropy field of 1.4 Oe for 12 and 24 mu m and 2.4 Oe for 7 Am microwire diameters. When comparing these results with those obtained for glass-coated microwires of the same nominal composition, we observed a decrease in the anisotropy field, as a result of the absence of the magnetoelastic contribution which was eliminated by removing the glass from the microwires. Giantmagnetoimpedance measurements at 10 MHz show an anisotropy field of 1.4 Oe for 12 and 24 mu m and 2.4 Oe for 7 mu m microwire diameters, in very good agreement with LFA results.