Micromagnetic Study of Forced Oscillation of Magnetic Domain Wall in Ferromagnetic Nanowires with Variation of Damping Constant

We have investigated a DW motion driven by AC external field with a variation of damping parameter α in Landau–Lifshitz–Gilbert equation as well as a variation of an oscillating force frequency by means of a micromagnetic simulation. Straight ferromagnetic wires having a DW at the wire center is considered, where the DW is assumed to behave like a free quasiparticle. With variation of strength and frequency of the external AC field, we have observed that relative phase delays between the forced DW motion and the AC field depends on the damping constant. The overall behavior is explainable with a single-degree-of-freedom model of a damped forced oscillation without a restoring force.