Magnetic permeability after‐effect in Fe–Cr–B and Fe–Cu–B amorphous systems

Room temperature measurements of magnetic permeability after‐effect, specific magnetization, and linear magnetostriction are performed on amorphous ribbons of compositions Fe_80−yCr_yB₂₀, Fe_80−yCu_yB₂₀, Fe_85−yCr_yB₁₅(0≤y≤5) to study the role of compositional and structural contributions to magnetic time effects of amorphous ferromagnets. The aftereffect is found to decrease with decreasing Fe content. Its behavior, however, is clearly independent of the type of transition metal added to the Fe–B matrix, although Cr and Cu interact quite differently with boron atoms. These results show that the magnetic aftereffect of amorphous alloys is not related to the ordering of metalloid atoms. The experimental data are instead discussed in terms of a new theory, relating the aftereffect to the magnetostrictive interaction between the atomic‐level shear stress fluctuations frozen in rapidly quenched alloys, and the magnetization direction. The agreement between the present results and the theory gives further support to the hypothesis of a structural nature of the aftereffect measured in amorphous ferromagnets.