Effect of dopants on magnetic and magnetoimpedance properties of rapidly solidified FeCoBM (M = Al, Cu and Si) ribbons

In this work magnetic properties, magnetoimpedance (MI) and field sensitivity (eta) of rapidly solidified (Fe0.7Co0.3)(80)B19M1 (M = B, Al, Si & Cu) ribbons have been investigated in the frequency range 0.5 - 13 MHz. Present study shows replacement of boron (B) by a nonmagnetic element (Al, Si or Cu) can alter the thermal stability, soft magnetic and magnetoimpedance properties of the(Fe0.7Co0.3)(80)B-20 ribbons. It is found that saturation magnetization reaches the largest value for Cu-containing sample and the smallest value for Al-containing sample. The MI studies show maximum MI ratios 30% at 5 MHz, 23% at 7 MHz, 26% at 3 MHz and 39% at 4 MHz for M = B, Al, Si & Cu respectively. Variation of MI with external magnetic field shows single peak behavior of Al-content ribbon over the entire frequency range, whereas for all other samples single peak converted to double peak at higher frequency, which indicates existence of stronger longitudinal magnetic anisotropy in Al-containing ribbon. The MI variation with magnetization, M and damping constant, alpha is also validated through numerical simulations using standard electrodynamics models. Present study reveals that the variations of MI response are associated with formation of soft magnetic phase and development of anisotropy with replacement of B by an additional element.

Automated summary

The study investigates the magnetic properties, magnetoimpedance, and field sensitivity of rapidly solidified ribbons with different nonmagnetic elements. The saturation magnetization was found to vary with the type of element added, with the highest value for Cu and the lowest for Al. Magnetoimpedance ratios showed different peak behaviors at different frequencies, indicating the presence of stronger magnetic anisotropy in Al-containing ribbons. The study also validated the variations in magnetoimpedance response with the formation of soft magnetic phase and development of anisotropy due to the replacement of boron with an additional element.