Influence of frequency and bias current on asymmetrical, GMI effect in Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires

The Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires (AGCW) are prepared by the Taylor-Ulitovsky technique. The frequency dependence of asymmetrical giant magneto-impedance (AGMI) effect in amorphous glass-covered wires annealed by 70 mA DC current is here presented. The resistance R and the reactance X have been measured, respectively. The real part R and the imaginary part X of impedance play an important role at high frequency and low frequency, respectively. The influence of DC bias current from I-b = 0 mA to I-b = 5 mA at 30 MHz on the GMI effect in the glass-covered wires annealed by 70 mA DC current is investigated. The asymmetry becomes the largest around I-b = 1 mA, and finally decreases for the larger bias current I-b = 5 mA. The maximum Delta Z/Z ratio of 310% is observed at 58 MHz under 1 mA bias current.