Magnetization reversal and small lancettes calculated by statistic domain behavior (abstract)

Abstract

The energetic model of ferromagnetic hysteresis calculates the magnetic state of anisotropic ferromagnetic materials by minimizing the total energy function ET=EH+EM. The energy of the material EM is divided into reversible (statistic domain behavior) and irreversible terms. The applied field H (energy EH) causes reversible domain wall displacements si until an individual Barkhausen jump starting position sA is reached. The probability density pa(sA) is assumed to be decreasing with increasing sA: pa=(Ka/Kc)exp [−(Ka/Kc)sA] (adaptive constant Ka). Kc describes the influence of the total magnetic state on pa at points of magnetization reversal; Kc=1 for the initial magnetization curve. The losses Er during an irreversible Barkhausen jump (wall friction Kr) are increasing with si: Er=Kr[si−sA−(Kc/Ka)(Kc−1)] and Kc depends on the covered displacements si at a point of field reversal: Kcnew=2−Kcboldexp[−(Ka/Kcold) si]. This follows from the condition of steadiness at these points. The physical constants of this model are derived from anisotropic energy contributions, initial susceptibility, coercivity, and saturation magnetization. The approach shows a good agreement to measurements to the stability of small lancettes of (110)[001] 3.5% FeSi steel sheets, magnetized in the rolling direction.