Magnetoimpedance studies on (Fe<inf>70</inf>Co<inf>30</inf>)<inf>80</inf>B<inf>20-x</inf>Si<inf>x</inf> amorphous ribbons

In the present work, magnetic and magnetoimpedance (MI) properties of (Fe70Co30)80B20-xSix (x = 0, 3, 5, and 10) amorphous ribbons in the frequency range of 500 kHz-13 MHz are reported. Our studies show that the thermal stability, magnetic behavior, and MI profiles have been strongly influenced by the Si content in amorphous ribbons. The magnetic isotherms show that all the samples of present study attain magnetic saturation values well below 500 Oe with coercivity values in the range of 0.2-0.09 Oe, which suggest ultrasoft nature of the samples. Interestingly, MI follows the magnetization variations with Si content. A maximum MI and field sensitivity of 46% and 4.3%, respectively, have been achieved for 10% B replacement by Si. The results show that the skin depth is strongly modified by the addition of Si, which in turn affects the impedance. The MI profiles show double peak and triple peak nature, which indicates the presence of transverse magnetic domain in all samples.