Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.49: Poster

Tuesday, March 23, 2010, 14:45–16:30, Poster C

Hydrogen absorption in Gd thin films and islands — •Sara Wanjelik, Georg Oeltzschner, and Mathias Getzlaff — Institute of Applied Physics, University of Düsseldorf

The absorption process of hydrogen in thin Gd(0001) films deposited on a W(110) substrate has been investigated by means of scanning tunneling microscopy (STM) and spectroscopy (STS). The adsorption as the previous step is imaged using the fact that clean and well-ordered Gd surfaces exhibit a highly localized surface state near the Fermi edge which is suppressed due to the adsorption of hydrogen. The surface state reappears after the subsequent diffusion of hydrogen into the bulk material. Thus, we are able to observe the temporal development of the absorption process.

In this contribution we will discuss the absorption behaviour for different layer thicknesses to determine the influence of the respective bulk material because the creation of GdH₂ results in a lattice expansion of about 14%. Due to the adherence of the film on the substrate this expansion occurs only in the perpendicular direction. This is different for free standing nanoislands which are only clamped at the interface. Thus, investigations concerning the absorption behavior are also performed on the size dependence of Gd islands to compare these results with those from thin films.