Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 6: Metal Substrates: Clean Surfaces

O 6.6: Vortrag

Montag, 25. Februar 2008, 12:30–12:45, MA 005

Surface electronic structure of Y(0001): A consistent picture — •Michael Budke, Juliet Correa, and Markus Donath — Physikalisches Institut, WWU Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

The photoemission (UPS) spectra of the (0001) surfaces of rare earth single crystals like Sc, Pr, Y, Gd, Tb, Ho and Er show an intense feature at about 10 eV binding energy. Its sensitivity to the degree of surface order led to the acronym surface order dependent state(SODS) in the literature [1]. For more than 20 years it remains an unsolved puzzle why the SODS was not observed in photoemission data obtained from clean rare-earth thin films grown on W(110) or Mo(110). On the one hand, experiments performed on rare earth single crystals are known to suffer from inherent impurities. On the other hand, thin films grown on W(110) or Mo(110) are of higher purity but not as well ordered as single crystals due to the considerable lattice mismatch between substrate and film. In our contribution, we give a consistent picture of the surface electronic structure of Y(0001) that explains the differences between single-crystal and thin-film UPS data. Furthermore, we provide evidence that the SODS is in fact due to carbon contamination, and not, as believed for more than 20 years, an indicator for a well prepared, highly ordered surface.

[1] S.D. Barrett, Surface Science Reports 14, 271 (1992).