Magnetic domain wall skyrmions

Abstract

It is well established that the spin-orbit interaction in heavy metal/ferromagnet heterostructures leads to a significant interfacial Dzyaloshinskii-Moriya interaction (DMI), which modifies the internal structure of magnetic domain walls (DWs) to favor N\'eel- over Bloch-type configurations. However, the impact of such a transition on the structure and stability of internal DW defects (e.g., vertical Bloch lines) needs to be explored. We present a combination of analytical and micromagnetic calculations to describe a type of topological excitation called a DW skyrmion characterized by a ${360}^{\ensuremath{\circ}}$ rotation of the internal magnetization in a Dzyaloshinskii DW. We further propose a method to identify DW skyrmions experimentally using Fresnel-mode Lorentz transmission electron microscopy; simulated images of DW skyrmions using this technique are presented based on the micromagnetic results.