Amorphous ribbons Fe73.5-xMnxSi13.5Nb3Cu1 (x=1, 3, 5) were prepared by rapid quenching on
a single rotated copper wheel. The X-ray patterns show that the as-cast samples are amorphous. The
measurements of thermomagnetic curves indicated that the Curie temperature of the amorphous phase of the
samples decreased with increasing Mn content. The optimal heat treatment was performed at Ta=535 ?C for
1 h and showed that the ultrasoft magnetic properties of nanocomposite materials were obtained. The
frequency dependence of magnetoimpedance was measured in the frequency range of 1-10 MHz and at a
fixed current of 10 mA. The correlation between the MI effect and the soft magnetic properties is discussed.
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