Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 78: Surface Dynamics I

O 78.12: Talk

Thursday, March 14, 2013, 18:45–19:00, H42

Surface Dynamics of Sb(111) Measured with Helium Atom Scattering — •Michael Mayrhofer-Reinhartshuber, Anton Tamtögl, Patrick Kraus, Markus Polanz, and Wolfgang E. Ernst — Institute of Experimental Physics, Graz University of Technology, Graz, Austria

Especially due to its appearance in a group of compounds belonging to the lately discovered class of topological insulators, the semimetal antimony (Sb) is an interesting candidate for investigations of its surface properties. Recently the surface phonon dispersion curve of Sb(111) was calculated using density functional perturbation theory [1], but there has been a lack of experimental data.

First Helium Atom Scattering measurements of the Sb(111) surface were performed by our group, showing sharp diffraction peaks in good agreement with the already known surface structure. The analysis of resonance features in our spectra revealed three bound states. The best fit helium-surface interaction potential shows a pure van der Waals character. By using time-of-flight measurements the surface phonon dispersion was obtained. The acoustic modes are in good agreement with ab-initio calculations. In analogy to measurements on Bi(111) [2, 3], vibrations of the electron corrugation originating in displacements of atoms in the second bilayer were detectable. These subsurface modes can only be observed by HAS because of the electron phonon coupling.

[1] D. Campi et al., Phys. Rev. B. 86 (2012) 075446

[2] M. Mayrhofer-Reinhartshuber et al., JPCM 24 (2012) 104008

[3] T. Tamtögl et al., Phys. Rev. B., submitted 2012