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MM: Fachverband Metall- und Materialphysik

MM 31: Postersitzung II

MM 31.3: Poster

Wednesday, March 16, 2011, 17:15–18:45, P5

Structural changes of Gd thin films and islands during hydrogen absorption — •Sara Wanjelik, Georg Oeltzschner, and Mathias Getzlaff — Institute of Applied Physics, University of Düsseldorf

We report on the effects of hydrogen absorption in Gadolinium Systems by using scanning tunneling microscopy (STM) and spectroscopy (STS).

Offering low amounts of hydrogen (1-2 L) to thin films results in the adsorption on the surface. Adsorbed hydrogen changes the electronic structure of the affected areas due to supression of the surface state of Gd (0001). After the subsequent diffusion of hydrogen into the underlying layer the surface state reappears. This can be observed using STS and STM. This change in the electronic structure causes a voltage dependent corrugation which changes sign at 0.8 V. It was observed that the inversion of the corrugation for islands occurs at higher voltages.

For higher dosage (>50 L) not only the electronic structure is affected but also the topographic structure. As a result we found small circular islands (diameter 6-8 nm) and ramp-like structures exhibiting the height of one atomic step. The topographic change of the surface can be ascribed to hydride formation (GdH₂) in the thin film. This obsevation will be compared to the behavior of islands during hydrogen absorption.