Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 12: Surface dynamics
O 12.7: Talk
Monday, March 26, 2012, 17:30–17:45, H 2013
Phonon density of states of ultra-thin europium films from in-situ 151Eu nuclear inelastic scattering — •Olga Bauder1, Marthe Kaufholz2, Marchin Zajac3, and Svetoslav Stankov1,2 — 1Laboratory for Applications of Synchrotron Radiation, KIT, Germany — 2Institute for Synchrotron Radiation, KIT, Germany — 3European Synchrotron Radiation Facility, Grenoble, France
It is well known that in thin films atoms vibrate in a manner significantly different as compared to the bulk. This is attributed to the broken translation symmetry and consequently to the reduced coordination of the surface atoms. For 3d metals these anomalies were investigated both theoretically and experimentally for the Fe(110) surface. However, there are no studies for the surfaces of 4f metals reported so far. We have investigated the phonon DOS of epitaxial ultra-thin Eu metallic films by in-situ nuclear inelastic scattering on 151Eu. The results reveal striking deviations of the phonon spectra of 1.1 nm thick film compared to that of bulk Eu. By reducing the film thickness, a systematic hardening, instead of softening of the phonon DOS is detected. * S.S. acknowledges the support by the Helmholtz Association for establishing a Helmholtz-University Young Investigator Group "Interplay between structure and dynamics in epitaxial rare earth nanostructures" (VH-NG-625).