DEEN

Research - Exotic Surfaces

Electronic dispersion of typical Dirac materials — The electronic dispersion of graphene (left panel) and a topological insulator (right panel, ARPES measurements from the University of Aarhus).

Molecular dynamics simulation showing the motion of a corannulene molecule at a graphite surface — (Start on click) Molecular dynamics simulation of a corannulene molecule moving over a graphite surface.

Helium atoms are scattered by the electron density on the surface. Elastic scattering upon an ordered surface gives rise to diffraction peaks analogous to X-ray scattering. In the event of inelastic scattering the helium atom looses or gains energy via en — Graphical representation of different helium atom scattering processes on a crystal surface.

We are interested in the interaction of surfaces with its environment. In particular, we are working on surfaces of the material classes of Dirac materials, including the so-called topological insulators which are promising candidates for potential applications in spintronics and quantum computation. Our goal is, to advance the fundamental understanding of these materials by studying surface dynamical processes and the atom-surface interaction with helium atom scattering.

We are also trying to obtain a better understanding of the nanoscale motion of molecules on surfaces. Experimental information is obtained in collaboration with a group in Cambridge and the Institute Laue Langevin in Grenoble. The video on the left, shows the motion of a corranulene molecule (buckybowl) on a graphite surface.

Helium atom scattering (short: HAS) is a technique used to analyse all kind of surfaces since it provides information both about the surface structure and lattice dynamics of a material. The whole scattering apparatus is set up in an ultra high vacuum chamber together with some other commercial surface analysis techniques such as AES (Auger electron spectroscopy) and LEED (low energy electron diffraction). A detailed description of the technique can be found here

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All images © TU Graz/Institute of Experimental Physics

Helium Atom Scattering

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