Stabilization of coupled Dzyaloshinskii domain walls in fully compensated synthetic anti-ferromagnets

TL;DR

This study investigates how interlayer exchange coupling and interfacial Dzyaloshinskii-Moriya interaction influence the structure of magnetic domain walls in synthetic anti-ferromagnets, using Lorentz TEM to confirm the presence of Dzyaloshinskii domain walls.

Contribution

It demonstrates control over domain wall structure and chirality in SAFs through multilayer design and DMI tuning, confirming the existence of Dzyaloshinskii domain walls in high DMI SAFs.

Findings

Confirmation of anti-ferromagnetically coupled Dzyaloshinskii domain walls in high DMI SAFs

Control of domain wall structure via multilayer design and DMI strength

Unique LTEM contrast conditions for observing Dzyaloshinskii domain walls

Abstract

We examine the combined effects of interlayer exchange coupling (IEC) and the interfacial Dzyaloshinskii-Moriya Interaction (DMI) on the structure of magnetic domain walls in fully compensated synthetic anti-ferromagnets (SAFs). Ir-based SAFs with ferromagnetic (FM) layers based on [Pt/(Co/Ni)M]N were characterized by Lorentz transmission electron microscopy (LTEM). The multi-layer design of the individual ferromagnetic layers enables control of the interfacial Dzyaloshinskii-Moriya interaction (via 'M') and, in turn, the structure and chirality of domain walls (DWs). We compare the Fresnel-mode LTEM images in SAF designs with only a change in the purported strength of the DMI. The existence of anti-ferromagnetically coupled Dzyaloshinskii domain walls (DWs) in a high DMI SAF is confirmed through application of in-situ perpendicular magnetic field and sample tilt. This conclusion is based on a unique set of conditions required to observe contrast in Fresnel-mode LTEM, which we outline in this document.