Permeability and giant magnetoimpedance in Co69Fe4.5X1.5Si10B15 (X=Cr, Mn, Ni) amorphous ribbons

The magnetoimpedance (MI) has been measured in the amorphous ribbons of the soft ferromagnetic alloy Co69Fe4.5X1.5Si10B15 (X = Cr, Mn, Ni) as functions of frequency (f ). For all of the three samples, at low frequency, f less than or equal to 5 MHz, the MI ratio increases with increasing frequency, but the MI ratio decreases at high frequency, f greater than or equal to 5 MHz. The MI profiles are not changed at low frequency regions of f less than or equal to 1 MHz in the amorphous ribbons. The MI ratio at high frequency of f = 5 MHz becomes 57% in Co69Fe4.5Cr1.5Si10B15, but the MI ratio becomes 30% in Co69Fe4.5Mn1.5Si10B15 and Co69Fe4.5Ni1.5Si10B15. The MI ratio at f = 10 MHz becomes 45% in Co69Fe4.5Cr1.5Si10B15 and the MI ratio becomes 23% in Co69Fe4.5Mn1.5Si10B15 and Co69Fe4.5Ni1.5Si10B15, respectively. The maximum values of field sensitivity are 2.7(X = Cr), 2.5(X = Mn), 2.2(X = Ni)%/Oe for f = 5 MHz. (C) 2001 American Institute of Physics.