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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 17: Skyrmions III (joint session MA/TT/KFM)
KFM 17.9: Vortrag
Mittwoch, 14. März 2018, 17:00–17:15, EB 301
First-principles study of skyrmion formation at 3d/4d transition-metal interfaces — •Soumyajyoti Haldar1, Stephan von Malottki1, Pavel F. Bessarab2, and Stefan Heinze1 — 1Institute of Theoretical Physics and Astrophysics, University of Kiel, 24098, Kiel, Germany — 2School of Engineering and Natural Sciences, University of Iceland, 107, Reykjavik, Iceland
Typically, it is assumed that for the formation of skyrmions with a diameter of a few nanometers a 3d/5d transition metal (TM) interface is required due to the large spin-orbit coupling of heavy TMs which leads to large Dzyaloshinskii-Moriya interaction (DMI). Here, we use density functional theory (DFT) as implemented in the FLEUR code [1] to demonstrate that ultrasmall skyrmions can also emerge at 3d/4d TM interfaces. We have calculated the magnetic interactions in atomic bilayers of Pd/Fe on the Rh(111) surface – a system which is similar to Pd/Fe/Ir(111) [2, 3] since Rh and Ir are isoelectronic 4d- and 5d-TMs. From our DFT calculations we parametrize an atomistic spin model including exchange interactions, DMI and the magnetocrystalline anisotropy energy (MAE). We find that both DMI and MAE are reduced with respect to Pd/Fe/Ir(111) which still allows a spin spiral phase at zero magnetic field due to DMI. Using spin dynamics simulations we find that a skyrmion phase occurs for both fcc and hcp stacking of the Pd layer at small magnetic fields of ∼ 1 T. Depending on the stacking the skyrmion diameters amount to 4 to 6 nm.
[1] http://www.flapw.de [2] N. Romming et al., Science 341, 6146 (2013) [3] B. Dupé et al., Nature Comm. 5, 4030 (2014).