The dynamics of the sandwich domain structure in 3%Si–Fe sheets

Abstract

Two types of the domain walls motion equations have been derived in which a step-like movement character and polarization of the domain walls parallel to the magnetic sheet plane and forming a sandwich domain structure were take into account. The deduced equations permit to calculate the domain walls coordinates x ̄ (τ) in this structure and the damping coefficient β( x ̄ ) or the demagnetizing field H d ( x ̄ ) in each domain wall plane during one cycle of the dynamic magnetization reversal accompanied by the Matteucci emf appearance. The steps shape of the moving domain walls is non-essential for these equations. With the help of the derived equations it has been discovered that the interaction of the 3%Si–Fe two sheets by means of the transverse magnetic stray fields leads to formation of the sandwich domain structure in each sheet during dynamic (200 Hz) magnetization reversal. The appearance, the movement direction, the velocity and annihilation of the magnetization reversal fronts in each sheet are determined by local demagnetizing fields and by the magnetic fields of eddy currents. The first front appears in each sheet at the beginning of each semiperiod of the magnetization reversal close to the contact surface of sheets. In Δτ≈0.8 ms on an opposite surface of each sheet the second magnetization reversal front appears and it moves toward the first one. Before the collision of the fronts close to the sheet middle the first front changes the movement direction and both fronts move to the contact surface of the sheets. The simultaneous one way movement of the fronts is accompanied by the decrease of their mutual distance.