Layer-resolved imaging of domain wall interactions in magnetic tunnel junction-like trilayers

TL;DR

This study uses high-resolution microscopy to investigate how domain walls in layered magnetic materials interact, revealing that stray fields cause antiparallel coupling over micrometer distances, especially in charged domain walls.

Contribution

It provides the first layer-resolved microscopic analysis of domain wall interactions in magnetic trilayers, highlighting the role of stray fields in coupling behavior.

Findings

Domain walls in the Co layer influence the FeNi layer's magnetization.

Stray fields induce antiparallel coupling between layers.

Charged domain walls exhibit long-range interactions up to several micrometers.

Abstract

We have performed a layer-resolved, microscopic study of interactions between domain walls in two magnetic layers separated by a non-magnetic one, using high-resolution x-ray photoemission electron microscopy. Domain walls in the hard magnetic Co layer of a Co/Al2O3/FeNi trilayer with in-plane uniaxial anisotropy strongly modify the local magnetization direction in the soft magnetic FeNi layer. The stray fields associated to the domain walls lead to an antiparallel coupling between the local Co and FeNi moments. For domain walls parallel to the easy magnetization axis this interaction is limited to the domain wall region itself. For strongly charged (head-on or tail-to-tail) walls, the antiparallel coupling dominates the interaction over radial distances up to several micrometers from the centre of the domain wall.