Complex Permeability After-Effect and Analysis of Power Losses in Ferromagnetic Co-Based Amorphous Alloy

Complex permeability $(μ=μ_1-iμ_2)$ after-effect of near-zero magnetostrictive CoFeCrSiB amorphous alloy was investigated in magnetic field H (t)= $H_0$ exp ( i 2π f t) after demagnetization. For frequencies f from 200 Hz to 2000 Hz and for the small amplitude H_0 < $H_{cr}$ we observed practically constant both real $μ_1$ and imaginary part $μ_2$ of permeability. A measured small decrease in the real part $μ_1$ and increase in the imaginary part $μ_2$ with frequency f were theoretically calculated for a quadratic form of a domain wall potential $E_S$ (x)=1/2α $x^2$. The calculated loss factortan δ = $μ_2 μ_1$, which is small at amplitude $H_0$ < $H_{cr}$, corresponds to power losses due to eddy currents induced around reversibly moving domain walls.