Modeling the nonlinear dynamics of magnetic domain walls

Abstract

We present the results of numerical simulations of dynamical processes in a moving domain wall (DW) in a ferrite thin film with out-of-plane anisotropy. The equations of motion include a coercivity, designed by a potential relief, which has a periodic part and a monotonous increasing part. The AC magnetic field of amplitude H ‖ causing the displacement of DW is parallel to the anisotropy axis. A Windows application was built, which among others contains in the menu the calculation of temporal series of q (the position of the center of DW), ψ (the amplitude of the magnetization azimuth angle oscillations) and Δ (the width of the wall). The results obtained shows that: for H ‖ small, the DW oscillations are regular and ψ is small; the amplitude of q increase with H ‖, and so does ψ; at large H ‖ the DW oscillations become chaotic and it is possible that the precession of the magnetization appear; when H ‖ took very large values the precession is strong and the wall displacement is limited. An applied transversal magnetic field H ⊥ may lead to a reduction of the instabilities of the oscillations.