Journal Article

FZJ-2020-03143

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Material systems for FM-/AFM-coupled skyrmions in Co/Pt-based multilayers

Jia, H. (Corresponding author)FZJ* ; Zimmermann, B. ; Hoffmann, M.FZJ* ; Sallermann, M.FZJ* ; Bihlmayer, G.FZJ* ; Blügel, S.FZJ*

2020
APS College Park, MD

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Please use a persistent id in citations: http://hdl.handle.net/2128/25777  doi:10.1103/PhysRevMaterials.4.094407

Abstract: Antiferromagnetically coupled magnetic skyrmions are considered ideal candidates for high-density information carriers. This is due to the suppressed skyrmion Hall effect compared to conventional skyrmions and a smaller size due to the cancellation of some contributions to the magnetostatic dipolar fields. By means of systematic first-principles calculations based on density functional theory we search for suitable materials that can host antiferromagnetically coupled skyrmions. We concentrate on fcc-stacked (111)-oriented metallic $Z$/Co/Pt ($Z=4d$ series: Y$-$Pd, the noble metals: Cu, Ag, Au, post noble metals: Zn and Cd) magnetic multilayers of films of monatomic thickness. We present quantitative trends of magnetic properties: magnetic moments, interlayer exchange coupling, spin stiffness, Dzyaloshinskii-Moriya interaction, magnetic anisotropy, and the critical temperature. We show that some of the $Z$ elements (Zn, Y, Zr, Nb, Tc, Ru, Rh, and Cd) can induce antiferromagnetic interlayer coupling between the magnetic Co layers, and that they influence the easy magnetization axis. Employing a multiscale approach, we transfer the micromagnetic parameters determined from $ab$ $initio$ to a micromagnetic energy functional and search for one-dimensional spin-spiral solutions and two-dimensional skyrmions. We determine the skyrmion radius by numerically solving the equation of the skyrmion profile. We found an analytical expression for the skyrmion radius that covers our numerical results and is valid for a large regime of micromagnetic parameters. Based on this expression we have proposed a model that allows to extrapolate from the $ab$ $initio$ results of monatomic films to multilayers with Co films consisting of several atomic layers containing 10-nm skyrmions. We found thickness regimes where tiny changes of the film thickness may alter the skyrmion radius by orders of magnitude. We estimated the skyrmion size as function of temperature and found that the size can easily double going from cryogenic to room temperature. We suggest promising material systems for ferromagnetically and antiferromagnetically coupled spin-spiral and skyrmion systems.

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Contributing Institute(s):

1. Quanten-Theorie der Materialien (PGI-1)
2. Quanten-Theorie der Materialien (IAS-1)
3. JARA-FIT (JARA-FIT)
4. JARA - HPC (JARA-HPC)

Research Program(s):

1. 142 - Controlling Spin-Based Phenomena (POF3-142) (POF3-142)
2. 143 - Controlling Configuration-Based Phenomena (POF3-143) (POF3-143)
3. Systematic investigation of magnetic thin films and multi-layers - towards sub-10nm skyrmions for future data storage devices (jara0197_20191101) (jara0197_20191101)
4. Magnetic Anisotropy of Metallic Layered Systems and Nanostructures (jiff13_20191101) (jiff13_20191101)

Appears in the scientific report 2020

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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