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MA: Fachverband Magnetismus
MA 28: Thin Films: Magnetic Anisotropy
MA 28.8: Talk
Wednesday, March 20, 2024, 16:45–17:00, EB 107
Thickness-dependent magneto-ionic effects in Fe thin films — Ben Billinger1, Arne Vereijken2, Arno Ehresmann2, Karin Leistner1,3, and •Markus Gößler1 — 1Institute of Chemistry, Chemnitz University of Technology — 2Institute of Physics and CINSaT, University of Kassel — 3Leibniz IFW Dresden
Magneto-ionics promises the reconfiguration of magnetic materials in a reversible and non-volatile manner.[1] Magnetic thin films, owing to their large surface-to-volume ratio, are particularly promising. In this study, we investigate the influence of film thickness on the magneto-ionic effect caused by the oxidation/reduction of sputtered iron thin films in aqueous electrolytes. Our iron films (10-100 nm) are covered by a native magnetite layer, which can be electrochemically reduced to ferromagnetic iron and re-oxidized reversibly, providing the basis for our magneto-ionic response.[2] We measure smaller coercivities in the reduced state, compared to the oxidized and pristine states, utilizing our in situ electrochemical Kerr microscopy setup.[2] The magnitude of the magneto-ionic effect, measured by relative changes in coercivity, can be enhanced to over 50% at small film thicknesses. For the smallest Fe thicknesses, the initial four-fold in-plane anisotropy of Fe levels out after magneto-ionic cycling, revealing a significantly increased coercivity compared to the pristine samples. We discuss our findings in terms of an increased surface roughness during reoxidation and highlight the importance of surface structure for future magneto-ionic devices. [1] M. Nichterwitz et al., APL Mater. 9, 030903 (2021), [2] J. Zehner et al., Adv. Electron. Mater. 6, 2000406 (2020)
Keywords: Magneto-Ionics; in-situ; Kerr-Microscopy; Surface Roughness; Iron