Barkhausen signal and magnetoelastic properties in soft magnetic materials

Abstract

Barkhausen signal(BS) and harmonics during half hysteresis loop and the magetostriction and elastic moduli at low magnetic field has been investigated as a function of magnetizing angle θ between [001] and applied field direction in grain oriented (110)[001] 3% SiFe, and applied tensile stress in as-quenched $Fe_81B_13.5Si_3.5C_2$ (2606SC) amorphous Metglas, respectively. For grain oriented (110)[001] 3% SiFe, the fields of second harmonic peaks at knees of hysteresis (B-H) loop relate to the nucleation and annihilation field, $H_n$ and $H_a$, respectively. The field interval of the second harmonic peaks is approximately described as $ΔH_{n, a}=2NM_s(θ)$. As the θ increase, the BS profile changes from double to triple peaks. The two side peaks (SP1 and SP2) on the BS profiles at knees of B-H loop are attributed to the domain nucleation and annihilation, because side peaks correspond to the peaks of the second harmonics. The side peaks on BS are discussed by the nucleation and annihilation of the 90˚ and 180˚ domain wall inside the volume fraction of main and closure domains. The center peak(CP), which is proportional to the ac susceptibility near zero field, due to the transformation of 180˚ main domains to closure domains. The magnetostriction along the field direction formulated in terms of the magnetostriction in $λ_[001]$ and $λ_[110]$ is explained by modified model for the volume fraction of the transferred closure domains from the [001] direction. The Young``s and longitudinal modulus measured by the resonance method are discussed by the pure elastic characteristics at low magnetic field, and the anisotropy of these moduli are well fitted using the elastic constants for the iron crystal having the cubic structure. For as-quenched $Fe_81B_13.5Si_3.5C_2$ Metglas the two stages variation of the initial permeability, second harmonics and $(BS)_tot$ with tensile stress reflects that the volume fraction of longitudinal domains along the stress direction increa...