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Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Magnetism Poster A

MA 15.62: Poster

Tuesday, April 2, 2019, 10:00–13:00, Poster E

Temperature-dependent red-shift of the absorption edge of thin ferromagnetic EuO-layersMarcel Ney1, Paul Rosenberger2, Patrick Lömker2, •Günther Prinz1, Martina Müller2,3, and Axel Lorke11Faculty of Physics and CENIDE, University of Duisburg-Essen, D-47057 Duisburg — 2Peter Grünberg Institut, Forschungszentrum Jülich GmbH, D-52428 Jülich — 3Faculty of Physics, TU Dortmund, D-44227 Dortmund

EuO-layers are interesting candidates for spin-filter applications in spintronic research. Below the Curie temperature of TC=69K, EuO becomes ferromagnetic, which has a strong influence on its optical band-gap.

We investigate the optical transmission of EuO-layers with thicknesses below 50nm from room temperature down to ≈25K. The EuO-layers are grown by a molecular-beam-epitaxy process on YSZ-substrates. Below the TC we observe a step-like shift of the absorption edge towards lower energies. This behavior can be explained by the magnetic exchange interaction, which leads to a splitting of the conduction band. Thinner layers not only show a blue-shift towards higher band-gap energies due to quantum confinement effects, but also exhibit a larger red-shift of the absorption edge during cooling below TC. This stronger red-shift of the absorption edge starts at lower temperatures compared with thicker samples, which is attributed to a reduced magnetic exchange interaction for very thin EuO-layers. In contrast to reports in the literature, we observe a monotonic red-shift of the absorption edge for different layer thicknesses.

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