Dresden 2014 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 6: Thin Film Characterization: Structure Analysis and Composition (XRD, TEM, XPS, SIMS, RBS,...)
DS 6.1: Vortrag
Montag, 31. März 2014, 15:00–15:15, CHE 89
Lattice Dynamics and Hyperfine Interactions in fcc Europium Islands — •Olga Bauder1,2, Przemyslaw Piekarz3, Anja Seiler1,2, Shyjumon Ibrahimkutty1,2, Daniel G. Merkel4, Marcin Zajac4, Rudolf Rüffer4, Tilo Baumbach1,2, Krzysztof Parlinski3, and Svetoslav Stankov1,2 — 1Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, Germany — 2Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Germany — 3Institute of Nuclear Physics, Polish Academy of Sciences, Poland — 4European Synchrotron Radiation Facility, France
Employing in-situ nuclear inelastic scattering on 151Eu we investigated the phonon DOS of fcc europium islands with a nominal coverage of 2, 3, 5, 10, and 24 monolayers (ML) grown on the Nb(110)/Al2O3 and compared the results with that of the bulk bcc Eu. The experimental results reveal a systematic shift of the phonon spectrum to high energies and significant suppression of the low-energy phonon modes as the nominal Eu coverage is reduced. The observed phenomenon is attributed to the notable lattice compression of about 9 % in the fcc Eu islands, as well as to the naturally formed monolayer of EuO on the oxygen-induced (6x2) reconstructed Nb(110) surface. These findings are supported by the in-situ nuclear forward scattering spectra that reveal the presence of quantum beats attributed to the difference between the isomer shift of the EuO interface layer and the metallic Eu.