Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 47: Poster III
MA 47.30: Poster
Donnerstag, 21. März 2024, 15:00–18:00, Poster D
Isotropic Exchange-Bias in Twinned Epitaxial Co/Co3O4 Bilayer — •Martin Wortmann1, Tapas Samanta1, Maik Gaerner1, Michael Westphal1, Johannes Fiedler2, Inga Ennen1, Andreas Hütten1, Tomasz Blachowicz3, Luana Caron1,4, and Andrea Ehrmann2 — 1Bielefeld University, Bielefeld, Germany — 2Bielefeld University of Applied Sciences, Bielefeld, Germany — 3Silesian University of Technology, Gliwice, Poland — 4Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
Exchange bias (EB) is a unidirectional anisotropy caused by interface coupling between a ferro- and an antiferromagnet. It causes a preferential direction of magnetization in the ferromagnet, which manifests as a shift of the hysteresis loop along the magnetic field axis. Here, we demonstrate a large EB of over 1000 Oe at 20 K in a twinned Co(111)/Co3O4(111) thin film epitaxially grown on sapphire(0001) with 6-fold rotational lattice symmetry, which is among the highest values reported for Co/Co1-yO systems. In such systems, the effect intensity is largest along the magnetic easy axes, which usually results in an anisotropy of the EB in epitaxial interfaces. However, we observed identical EB values for 0°, 15°, and 30° angles between the magnetic field and the nearest Co[002] magnetic easy axes. The measurements imply a relaxation of the magnetization to the nearest easy axis, suggesting increasingly isotropic EB fields with higher orders of rotational lattice symmetry.
Keywords: exchange bias; cobalt oxide; thin film; epitaxy