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

The influence of current annealing on magnetic properties of Joule-heated amorphous CO68.25Fe4.5Si12.25B15 glass-covered microwire (29.3 mum) is investigated. Annealing without applied stress can produce short-range order relaxation and consequently improves the sample's soft magnetic properties. The maximum relative change of impedance measured for a drive current frequency 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 applied current I-d = 70 mA). This value is about 10 times higher than the maximum value so far reported for glass-covered microwires. (C) 2000 Elsevier Science B.V. All rights reserved.