Giant magneto-impedance in glass covered microwires

Giant magneto-impedance ratio in glass covered Co68.5Mn6.5Si10B15 microwires, with different glass coat thickness, was measured as a function of de axial field (up to 10.5 kA/m) and frequency (f=0.5 MHz up to 30 MHz). A maximum GMI ratio of 58% was observed at 1.5 MHz. The frequency dependence of the GMI maximum and the position where it occurs is discussed in terms of the glass coat thickness