Besetzte und unbesetzte elektronische Struktur von geordneten Dünnschichtverbindungen der Seltenen Erden Eu und Yb mit den Übergangsmetallen Pd und Ni

The present thesis deals with the occupied and unoccupied electronic states of intermetallic compounds of the rare-earth metals (RE) Eu and Yb with the transition metals Pd and Ni. The compounds were prepared in-situ as epitaxial thin films on single-crystalline substrates. For comparison, the experiments were extended to a Ba/Pd compound, which was prepared in the same way. All samples were characterised by low-energy electron diffraction (LEED), photoelectron spectroscopy (PES) and inverse photoemission (IPE). For the IPE experiments an appropriate spectrometer was built. It consists of a combination of a toroidal-grating and a crystal monochromator and enables experiments with photon energies in the range of 10-25 eV and at 1486.6 eV. LEED experiments reveal the formation of a AuCu3 structure with a (111) surface orientation for RE/Pd systems, while the formation of a CaCu5-structure with (0001) surface orientation for the Ba/Pd and Eu/Ni compounds was found. The Eu compounds show a surface-valence transition from the trivalent to the divalent configuration. An ordered overstructure is formed at the surface despite an increase of the ionic volume of Eu by about 40 %. The measured electronic structure is in good accordance with results of local-density-approximation band-structure calculations.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Technische Universität Dresden

Year

2003

Author dc:creator

• Wieling, Sönke

Contributors dc:contributor

• Laubachat, Clemens
• Schneider, Wolf-Dieter.
• Dähne, Mario

• Eu
• Yb
• Ba
• Seltenerd-Übergangsmetallverbinungen
• Valenzübergang
• elektronische Struktur
• epitaktische Filme
• winkelaufgelöste Photoemission
• winkelauflösende inverse Photoemission
• angle-resoved inverse photoemission
• angle-resoved photoemission
• electonic structure
• epitaxial films
• rare earth-transition metal compounds
• valence transition