Magneto-impedance behaviour of Co-based glass-covered wires at microwave frequencies

Giant magneto-impedance (GMI) behaviour in amorphous Co68.25Fe4.5Si12.25B15 glass-covered wires has been studied in the frequency range 45 MHz-6 GHz. The experiments have been performed using a novel technique based on the S- parameter measurements by means of an automatic vector analyser. The GMI be haviour has been studied both in glass-covered samples and after glass remo val, showing an improvement of the S-parameter variation as a function of a n external magnetic field (H-max = 7000 A/m) in samples after glass removal . This effect is strictly connected with the change in the domain structure occurring after glass removal due to the reduction of the internal stresse s. (C) 2000 Elsevier Science S.A. All rights reserved.