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The magnetoimpedance (MI) of as-spun amorphous Co72−xFexZr8B20 (CFZB, x = 0, 2, 5, 7 at.%) alloys has been measured at a frequency ranging from 310 to 1110 kHz and a dc magnetic field between 0 to 70 Oe. The maximum MI ratio ΔZ/Z(%)max of the CFZB alloys increases with increasing frequency for each sample and decreases with the increment of Fe content at any frequency. The most drastic MI effect, the maximum value of about 90% at 1110 kHz accompanied by the field sensitivity of 18% Oe−1, is observed in CFZB without Fe. Magnetic measurements reveal that coercivity of CFZB decreases first and then increases with increasing Fe content, and the minimum value of about 1.6 Oe is obtained in the sample with x = 2 at.%. The permeability of CFZB was evaluated from quasi-static hysteresis loops, indicating that the Fe-free CFZB is of the largest permeability. Measurements on electrical resistivity suggest that the Fe-free sample possesses smaller resistivity while the sample with x = 7 at.% has a much larger resistivity compared with CFZB with 2 and 5 at.% Fe. The correlation between MI effect and magnetic properties together with electrical resistivity for the CFZB alloy is discussed in this paper.

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