Giant Magnetoimpedance effect at GHz frequencies in amorphous microwires

Magnetic properties and GMI effect of amorphous Co- rich microwires reveal that they present GMI effect at GHz frequencies. Frequency dependence of maximum GMI ratio has been evaluated. Magnetic field dependences of GMI ratio and frequency dependence of maximum GMI ratio are affected by the post-processing conditions. In particular, we observed that stress-annealing allows improvement of magnetic softness, GMI ratio and affects the frequency dependence of GMI ratio.