1. ABOUT THE DATASET -------------------- Title: Creator(s): Christopher E A Barker [1,2], Kayla Fallon [3], Craig Barton [2], Eloi Haltz [1], Trevor P Almeida [3], Sara Villa [3], Colin Kirkbride [3], Francesco Maccherozzi [4], Brice Sarpi [4], Sarnjeet S Dhesi [4], Damien McGrouther [3], Stephen McVitie [3], Thomas A Moore [1], Olga Kazakova [2], and Christopher H Marrows [1] Organisation(s): 1. University of Leeds, 2. National Physical Laboratory, 3. University of Glasgow, 4. Diamond Light Source Ltd. Rights-holder(s): Unless otherwise stated, Copyright 2024 University of Leeds Publication Year: 2024 Description: This dataset is associated with a paper on phase coexistence and transitions of a synthetic antiferromagnetic multilayer, and contains imaging using a number of different complimentary microscopies to study the transition mechanisms of the synthetic antiferromagnet. Samples were measured in the bulk using SQUID-VSM, imaged on the surface using magnetic force microscopy around the transition point and XMCD-PEEM at fields near zero, and imaged in transmission using both Fresnel and DPC Lorentz transmission electron microscopy at the transition point. This data was used to build up a picture of the transition mechanism of the synthetic antiferromagnet and image chiral textures therein. Cite as: Barker et al., (2024) Dataset associated with 'Phase Coexistence and Transitions between Antiferromagnetic and Ferromagnetic States in a Synthetic Antiferromagnet'. University of Leeds. [Dataset] https://doi.org/10.5518/1508. Related publication: Barker et al., Phase Coexistence and Transitions between Antiferromagnetic and Ferromagnetic States in a Synthetic Antiferromagnet, Phys. Rev. B (2024) (Accepted) Contact: Corresponding author is Christopher H Marrows: c.h.marrows@leeds.ac.uk 2. TERMS OF USE --------------- Copyright 2024 University of Leeds, National Physical Laboratory, University of Glasgow, Diamond Light Source. Unless otherwise stated, this dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: Synthetic Antiferromagnetic Skyrmions Dates: 01 MAR 2020 - 31 DEC 2023 Funding organisation: EPSRC Grant no.: EP/T006803/1 This project also received funding from EPSRC grant numbers, EP/T006811/1, EP/L015323/1, EP/S023321/1 and EP/T517896/1. This project also received funding from the UK Government Department for Science, Innovation and Technology through National Measurement Service funding (Low Loss Electronics). C.E.A. Barker also acknowledges funding from the National Physical Laboratory. We thank Diamond Light Source for the provision of beamtime under proposal MM-28586-1. 4. CONTENTS ----------- File listing Repository contains the following folders relating to each of the measurement methods. 1. SQUID-VSM: This contains the two hysteresis loops of S1 (SAF023_02) and S2 (SAF032_01), where column headers give the relevant units. 2. PEEM: This file contains the data from the PEEM at Diamond Light Source. Data is produced by the PEEM in hdf5 nexus database files, which can be accessed through the software 'HDFView'. These series of images were averaged to produce the .tif images also included. 3. MFM: Images from figure 4. These are raw phase data, where each image is 5 x 5 um. 4. Fresnel: This series of images over a range of fields forms figure 5 of the paper. Images are in .dm3 format which is used by the DigitalMicrograph software for analysis. Info.txt contains details of the magnetic field and pixel size etc. 5. DPC: This folder contains the DPC image used in figure 6, along with .csv files containing the linetraces. The Subfolder Field Series Expansion contains the images that were used to generate Table I, and contains th images in .dm3 and .tif form as well as some metadata in a .txt file. 6. Cross-Section: This folder contains cross section data of a sister sample to S2. The .dm3 files are the raw data for analysis in the software Digital Micrograph, and the png files are the results that were used to form figure 1. 5. METHODS ---------- SQUID VSM Data was taken using a Quantum Design MPMS3 SQUID-VSM at room temperature, with a oscillation amplitude of 5 mm. Samples were saturated first, and then magnetic field was swept from positive to negative saturation and back while measuring. PEEM Data was taken using the PEEM on beamline I06 at Diamond Light Source. Samples were first saturated ex-situ before being placed in the chamber mounted in a small coil catridge that was able to apply fields in-situ. The sample was held in a 20kV potential for measurements, and all measurements were performed at the Co L3 edge. During measurements the field was applied through the cartridge, and then the field returned to zero during measurement - so all images are at remanence. Analysis to average the individual images into the ones used in the paper was performed with the software IGOR PRO. MFM Data was taken using an Ntegra Aura Scanning Probe Microscope manufcatured by ND-MDT. Tips used were commercial LM probes manufactured by ND-MDT with a 40 nm coating of CoCr. Images presented in the paper were after first acquiring a II-pass MFM image, collecting topography and phase data. The images shown in the paper were acquired after this II-pass scheme, by fitting a plane to the topography and then scanning at a constant height collecting phase data. Samples were mounted on top of a electromagnet to apply fields in-situ. Analysis was performed using the software Gwyddion. A cross-sectional TEM lamella was prepared from a sister sample to S2 grown on a Si/SiOx substrate and transferred onto a Cu TEM grid using a Thermo Fisher ‌Helios Xe-plasma focused ion beam (PFIB) instrument. The TEM analysis in Fig. 1 and Lorentz microscopy described in this paper were carried out on a JEOL Atomic Resolution Microscope (JEM-ARM200cF) STEM, operating at 200~kV. This microscope is equipped with a cold field emission gun and a CEOS (Corrected Electron Optical Systems GmbH) probe corrector for STEM imaging. High-angle annular dark-field (HAADF) imaging and electron energy loss spectroscopy (EELS) analysis provided the localised elemental distribution within the SAF multilayer. The Digital Micrograph (DM) software package was used to analyse the EELS spectrum images and noise filtering was performed using a principle component analysis plugin. Fresnel images and 4D-STEM differential phase contrast (DPC) images were acquired on the same microscope operated in field-free mode. The Fresnel images were collected on a Gatan Orius CCD camera while the DPC data was collected on a MerlinEM hybrid-pixelated detector and induction maps were produced using a cross-correlation method. To image in static fields, the objective lens of the microscope is weakly excited and acts as a field source. For all Lorentz TEM methods (Fresnel and DPC) to produce contrast, the sample has to be tilted with respect to the electron beam (and optic axis) resulting in a small in-plane component to any applied field . The Fresnel images in Fig. 5 were acquired with a defocus of 2.2 mm. DPC images (shown in Fig. 6) were acquired with a 0.88 mrad semi-angle, giving a 3.5 nm probe, sampled with a 6.2 nm pixel size; and all images referenced in Table I were acquired with a 1.0 mrad semi-angle, giving a 3.5 nm probe, sampled with a 4.6 nm pixel size.