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DS: Fachverband Dünne Schichten

DS 28: Thin film characterization: structure analysis and composition (Spectroscopy)

DS 28.8: Talk

Wednesday, March 28, 2012, 19:30–19:45, H 2032

Lattice dynamics and magnetism of metallic Samarium in Sm-type and dhcp structured films — •Olga Bauder¹, Alessando Barla², Ilia Sergueev³, Rudolf Rüffer³, and Svetoslav Stankov¹ — ¹KIT, Karlsruhe, Germany — ²ALBA, Barcelona, Sapin — ³ESRF, Grenoble, France

The lattice dynamics of metallic samarium was unknown until recently. The high reactivity of Sm along with its large absorption cross section for thermal neutrons prohibited the application of inelastic neutron scattering, the standardly used method for determination of lattice dynamics. We determined the phonon density of states (DOS) of samarium by nuclear inelastic scattering on 149Sm. The experiments were performed at the end-station ID22N of the ESRF in Grenoble in a dedicated ultrahigh vacuum (UHV) system. 500 nm thick epitaxial Sm films exhibiting either the native for this metal Sm-type structure or the characteristic for the light lanthanides dhcp one were grown by molecular beam epitaxy following an elaborated procedure. In order to avoid oxidation and to reduce the multiphonon excitations the samples were investigated under UHV conditions and at 100 K. The magnetic properties of both structures were investigated by nuclear forward scattering in the temperature range 10 K - 300 K. From the phonon DOS a number of thermodynamic properties for this metal were determined. *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).*