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

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 Néel 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 s = −(1.07 ± 0.05) pJ m ⁄ is determined, which corresponds to a DMI energy per bond between two Co atoms at the interface of tot = −(1.04 ± 0.05) meV.

The microscopic origin of DMI in magnetic bilayers and prediction of giant DMI in new bilayers

“…A significant result is the giant DMI seen in six bilayers, namely, Re/Fe, Os/Fe, Re/Co, Os/ Co, Os/Ni and hexagonal Bismuth(hBi)/Ni. These materials show a DMI (d) up to twice the largest currently known values of 1.5 meV/ atom for Co/Pt 8 , −1.9 meV/atom for Ir/Fe 8 and −1.04 meV/atom for Ir/Co 36 . Note our predicted values of DMI (d) for these materials are 2.6 meV/atom for Co/Pt, −1.8 meV/atom for Ir/Fe and −1.8 meV/atom for Ir/Co.…”

Direct Imaging of Chiral Domain Walls and Néel‐Type Skyrmionium in Ferrimagnetic Alloys

“…In this study, we investigate the chirality of spin textures in a ferrimagnet namely Ta/Ir/Fe/GdFeCo/Pt by imaging the spin structure of the domain walls using SEMPA [25][26][27]. This surface-sensitive imaging technique has already been successfully used to determine the chiral character of out-of-plane (OOP) magnetized spin textures in ferromagnetic materials [28][29] and here we demonstrate that we can determine the chiral character of spin textures also for ferrimagnetic materials. From the SEMPA images, we are also able to extract the domain wall width across a wide range of temperatures, which allows us to determine the exchange stiffness evolution with temperature as a crucial parameter that governs the stability and operation temperature range.…”

2024 roadmap on magnetic microscopy techniques and their applications in materials science

“…By simultaneously measuring four symmetric scattering directions, two components of the spin-polarisation asymmetry are obtained simultaneously, usually corresponding to the two components of the magnetisation within the surface plane of the sample, as illustrated in figure 20. The missing out-of-plane component can be detected either permanently, by a 90 • electrostatic deflection of the detector axis, or subsequently, by an electromagnetic spin rotator [373], or simply by tilting the sample [374,375]. Due to the required vacuum environment, a wide range of sample temperatures can be easily accessed.…”