Optimization of giant magnetoimpedance effect in Co-rich glass-coated microwires by annealing

We studied the effect of annealing on the hysteresis loops and the Giant magnetoimpedance, GMI, ratio of Co72Fe4B13Si11 glass-coated microwire. A remarkable GMI ratio improvement up to 735% is observed after annealing at appropriate conditions. Observed magnetic softening and GMI ratio improvement have been discussed considering the internal stresses relaxation. The observed change in the hysteresis loop shape and in GMI ratio upon annealing correlate with a change in the magnetostriction coefficient sign and values with increasing of annealing temperature.