Report on imaging of individual skyrmions of MML systems made by different techniques

TL;DR

This report reviews various advanced magnetic imaging techniques used to visualize individual skyrmions in multilayer systems, providing crucial insights for skyrmion-based device development.

Contribution

It demonstrates the application of multiple state-of-the-art imaging methods to directly observe skyrmions, supporting material optimization and device research in magnetic multilayers.

Findings

Successful imaging of individual skyrmions using multiple techniques

Correlation between imaging results and theoretical models

Identification of skyrmion properties relevant for device applications

Abstract

Deliverable 1.1 is a report on imaging of individual skyrmions of MML systems made by different techniques. This deliverable falls within work package 1 (WP1:Static equilibrium properties of interface induced skyrmions in magnetic films and multilayers) of the MAGicSky research proposal whose objectives are: the growth of magnetic multilayer systems with large interfacial chiral interaction, the determination of the amplitude of the Dzyaloshinskii--Moriya interactions (DMi), the detailed structural and magnetic characterization of interfaces, the magnetic imaging of individual skyrmions and the thermal stability and interaction of skyrmions with intrinsic and/or artificial defects. It should be emphasized that imaging magnetic skyrmionic structures forms the basis for all the planned subsequent material optimization, electrical transport experiments and devices preparation in the MAGicSky research program. In particular, imaging is paramount as a technique since it enables us to unequivocally demonstrate chiral magnetic skyrmions by directly imaging i) the effects of engineering multilayer samples with large DMis and ii) the skyrmionic structure and properties. In order to get complementary physical insight on the properties of magnetic skyrmions and to corroborate our research results, we utilise a plethora of key state-of-the-art advanced magnetic imaging techniques, namely: i) Spin-polarised Scanning Tunnelling Microscopy (SP-STM), Scanning Transmission X-ray Microscopy (STXM) Lorentz Transmission Electron Microscopy (Lorentz TEM) as well as, Magnetic Force Microscopy (MFM). These imaging experiments can therefore stand as the base for all the other objectives in WP1 as well as WP2 that will study Dynamic properties: nucleation, propagation and detection of skyrmions. Imaging has been aimed to test and get feedback from the theoretical and numerical investigations of skyrmion systems of WP3. Finally, for WP4: Towards skyrmion based devices for information storage and processing, some of the techniques detailed here in D1.1 will enable us to image and test the first devices and their functionality. In short, the MAGicSky consortium research results in D1.1 constitute a major milestone that acts as a stepping-stone to every other experimental effort and we have achieved it. The results relevant to the D1.1 deliverable were presented in 5 publications and several invited talks at international workshop and conferences: