Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 77: Oxides and insulators: Epitaxy and growth
O 77.2: Vortrag
Donnerstag, 25. März 2010, 15:15–15:30, H42
Interface Oxides of Eu on Ni(100) — •Jürgen Klinkhammer, Daniel F. Förster, Carsten Busse, and Thomas Michely — II. Physikalisches Institut, 50937 Köln
Eu-oxides of submonolayer to few layer thickness were grown on Ni(100) at 350∘C through reactive molecular beam epitaxy with Eu fluxes of 2,04·1014 atoms m−1s−1. The resulting interface oxides are investigated through low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). As a function of the oxygen chemical potential at fixed Eu flux a sequence of interface oxide structures is observed. For the highest oxygen chemical potential polar EuO(111) starts to grow on Ni(100) with the densepacked [110] EuO direction aligned to the Ni[(011)]. For medium oxygen chemical potential a phase of small magic clusters coexists with a complex stripe phase. The magic clusters are immobile and decay upon heating. Finally for the lowest oxygen chemical potential applied a 5x5 superstructure forms, which uses as building blocks small, stable square clusters. It turned out that the 5x5 superstructure is well suited as interface oxide for subsequent growth of rather perfect and stoichometric EuO films. The polar EuO(111) interface oxide decays during subsequent growth through the formation triangular pyramids bounded by {100} facets and the film transforms to the nonpolar (100) orientation.