Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Postersession I

MM 17.2: Poster

Montag, 16. März 2015, 18:00–20:00, Poster E

Growth Process of Hydrogen Induced Structures on Gd Films and Islands Observed by STM — •Sara Wanjelik, Samuel Königshofen, and Mathias Getzlaff — Institute for Applied Physics, University of Düsseldorf

Hydrogen in metals as an area of research has been of great interest for the past decades. On the one hand this is caused by the technical application as hydrogen storage. On the other hand metal hydrogen systems are of great interest from a fundamental point of view. But only few investigations are carried out by imaging techniques with a lateral resolution on the nm-scale. Even less works deal with the initial stage of hydride formation.

Here we present STM measurements on thin Gadolinium films and islands grown on a W(110) surface under ultra high vacuum conditions. On Gd-films two kind of hydrogen induced modifications can be observed: Hydrides and small disc-like islands with a diameter of a few nm and a height of one atomic step. The discs form chains with clearly preferred directions. A triangular shaped structure is observed together with the discs. The growth process of these modifications were studied in detail. Electronic differences of the described structures were investigated by maps of differential conductivity.

Contrary to films islands can be penetrated by hydrogen from the side walls. Therefore, the hydride formation should start from the edges. Another difference to films is that not only a vertical expansion, due to the larger volume of the hydride, is possible but also a lateral.