Field-driven side-by-side magnetic domain wall dynamics in ferromagnetic nanostrips

TL;DR

This study numerically investigates the field-driven dynamics of in-plane side-by-side magnetic domain walls in ferromagnetic nanostrips, revealing complex behaviors and effects of Dzyaloshinskii-Moriya interaction, expanding understanding of domain wall physics.

Contribution

It provides new insights into the dynamics of in-plane side-by-side domain walls and the influence of DMI, which were less studied compared to out-of-plane or head-to-head domain walls.

Findings

Domain walls move rigidly at low fields.

Walker breakdown involves multi-step vortex nucleation.

DMI affects the Walker breakdown field depending on its type.

Abstract

There has been a plethora of studies on domain wall dynamics in magnetic nanostrips, mainly because of its versatile non-linear physics and potential applications in data storage devices. However, most of the studies focus on out-of-plane domain walls or in-plane head-to-head (tail-to-tail) domain walls. Here, we numerically study the field-driven dynamics of in-plane side-by-side domain walls in ferromagnetic strips, which can be stable in the presence of an in-plane easy-axis anisotropy transverse to the strip. The domain walls move in a rigid-body manner at low field, and show complex Walker breakdown behavior at high field. We observe a multi-step Walker breakdown through vortex nucleation in wide strips. In the presence of Dzyaloshinskii-Moriya interaction (DMI), the first Walker breakdown field first decreases then increases with interfacial DMI, while keeps increasing with bulk DMI. These findings complement the current understanding on domain wall dynamics.