Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 48: Oxide Semiconductors (jointly with HL)
DS 48.8: Vortrag
Freitag, 24. März 2017, 12:00–12:15, POT 51
Low temperature absorption study of ferromagnetic EuO thin films — •Marcel Ney1, Günther Prinz1, Timm Gerber2, Martina Müller1,2, and Axel Lorke1 — 1Faculty of Physics and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg — 2Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, D-52428 Jülich
Europium Oxide is a ferromagnetic semiconductor with the Curie temperature of 69K. When it is used as a tunnel barrier, it can create up to 100% spin polarized electron currents, for use in spintronic research. This remarkable property raises the question, how the magnetic order at low temperatures affects the band structure of a thin EuO layer.
Thin EuO-layers were grown by molecular beam epitaxy on yttria-stabilized-zirconia-substrates, with different thicknesses. A fourier-transform-infrared spectrometer equipped with a liquid helium continuous-flow cryostat was used to measure the transmission through the EuO thin films.
Spectra measured for decreasing EuO thickness (30nm-3nm) show a shift of the absorption edge of EuO to higher energies due to an increasing quantum confinement along the growth direction. For low temperature measurements below the Curie temperature of EuO, we observed a red shift of the bandgap energy of about Ea=(0.27 ± 0.02)eV. This energy shift is in good agreement with theoretical values and experimentally determined exchange splitting energies for thin europium-oxide layers, already published in the literature.