Vortex–antivortex pair driven magnetization dynamics studied by micromagnetic simulations

Abstract

Magnetization dynamics approaching an equilibrium vortex state from an initial nonequilibrium state under zero magnetic field has been studied in a circular-shaped Fe disk with a thickness of 5 nm and a diameter of 1200 nm using micromagnetic simulations. Upon starting from the initial random configuration of in-plane magnetizations, a great number of vortex ( V ) –antivortex ( V ¯ ) pairs are generated at a lot of nucleation sites where both types of V and V ¯ are energetically favorable to form. The V and V ¯ are propagated and then annihilated by their attractive interactions during the relaxation dynamic process. These results reveal that temporal magnetization evolutions can be dominated by the nucleation of V – V ¯ pairs, followed by their propagation and annihilation. The dynamic process driven by V – V ¯ pairs can play a significant role in various magnetization reversals.