Time and thermal stability of magnetic properties of amorphous Fe₈₀TM₃B₁₇ alloys

Abstract
We have investigated the influence of the addition of different transition metals (Fe, Co, Cr, Mn, Mo, Ni, Os, Pt, Ru, Ta, Ti, V and W) on the time-temperature stability of amorphous Fe₈₀TM₃B₁₇ alloys. Time stability is represented by the Magnetic After - Effect (MAE). Each element influences near neighbourhood of other atoms by its characteristic way which results in a different chracteristics of the MAE spectra and its spectra of activation energies. It turned out from our measurements that samples can be divided into the three groups : The first one contains alloys with MAE similar to that of an FeB alloy, in the second there are alloys with different MAE, and in the third one there are alloys with almost no MAE. It was found that MAE can be successfully described on the basis of the micromagnetic model with activation parameters Q* = 1.3 - 1.7 eV and τ₀ = 10^-18 - 10^-13. Small values of the preexponential factor points out that MAE in Fe₈₀TM₃B₁₇ amorphous alloys is caused by the rearrangement of the mobile atom pairs within the domain walls.