# Measuring the Dzyaloshinskii-Moriya interaction of the epitaxial Co/Ir(111) interface

## TL;DR

This study measures the Dzyaloshinskii-Moriya interaction at the epitaxial Co/Ir(111) interface using in situ microscopy, revealing how magnetic domain wall structures vary with cobalt thickness and quantifying the interfacial DMI strength.

## Contribution

It provides the first experimental quantification of the DMI at the epitaxial Co/Ir(111) interface with atomically flat growth, linking domain wall structure to DMI strength.

## Key findings

- Pure Néel walls below 8.8 ML cobalt thickness
- Transition to mixed Bloch-Néel domain walls at larger thicknesses
- Interfacial DMI parameter D_s = -1.07 pJ/m

## Abstract

The in-plane orientation of the magnetization in the center of domain walls is measured in Co/Ir(111) as a function of Co thickness via scanning electron microscopy with polarization analysis. Uncapped, thermally evaporated cobalt on an Ir(111) single-crystal surface is imaged in situ in ultra-high vacuum. The initial pseudomorphic growth with an atomically flat interface of cobalt on iridium ensures comparability to theoretical calculations and provides a study of an interface that is as ideal as possible. Below a cobalt thickness of 8.8 monolayers, the magnetic domain walls are purely N\'eel oriented and show a clockwise sense of rotation. For larger thicknesses the plane of rotation changes and the domain walls show a significant Bloch-like contribution, allowing to calculate the strength of the Dzyaloshinskii-Moriya interaction (DMI) from energy minimization. From the angle between the plane of rotation and the domain-wall normal an interfacial DMI parameter $D_s = -(1.07 \pm 0.05)$ pJ/m is determined, which corresponds to a DMI energy per bond between two Co atoms at the interface of $d_{tot} = -(1.04 \pm 0.05)$ meV.

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Source: https://tomesphere.com/paper/1902.05523