Magnetic properties and giant magnetoimpedance in a CoFeSiB glass-covered microwire

The influence of current annealing on magnetic properties of Joule-heated a morphous CO68.25Fe4.5Si12.25B15 glass-covered microwire (29.3 mum) is inves tigated. Annealing without applied stress can produce short-range order rel axation and consequently improves the sample's soft magnetic properties. Th e maximum relative change of impedance measured for a drive current frequen cy of 15 MHz is about 600% with a maximum slope sensitivity of 4%/A m(-1) ( about 320%/Oe) for special annealing conditions (10 min annealing with appl ied current I-d = 70 mA). This value is about 10 times higher than the maxi mum value so far reported for glass-covered microwires. (C) 2000 Elsevier S cience B.V. All rights reserved.