Micromagnetic simulation of magnetization reversal in submicron dots with laterally gradient magnetization

Micromagnetic simulation is performed on a ferromagnetic submicron dot with lateral gradient magnetization. The simulations show that the sub-dot with lateral gradient magnetization produces a two-stage magnetization reversal during nucleation. It is different from the magnetization reversal process in a dot with lateral uniform magnetization, which has only one sharp jump in magnetization, corresponding to an irreversible transition from a collinear to a vortex spin structure. The reversal process of the ferromagnetic dot with lateral gradient magnetization is also dependent on the direction of applied magnetic field.