Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 34: Elektronische Struktur IV

O 34.2: Vortrag

Donnerstag, 27. März 2003, 15:15–15:30, M\"UL/ELCH

Surface electronic structure of Ce metal — •Clemens Laubschat¹, Frederik Schiller¹, Vito Servedio^1,2, Yuri Kucherenko³, and Serguei Molodtsov¹ — ¹Institut für Oberflächenphysik und Mikrostrukturphysik, TU Dresden — ²Sezione INFM and Dip. di Fisica, Università “La Sapienza”, P. le A. Moro 2, 00185 Roma, Italy — ³Inst. of Metal Physics, National Academy of Science of Ukraine, UA-03142 Kiev, Ukraine

Structurally ordered films of γ-like Ce metal on W(110) were studied by means of angle-resolved photoemission (PE). Like for other trivalent rare-earth metals the valence-band structure at the surface is found to be dominated by a surface-state of large effective mass and hole-like dispersion. LKKR calculations are qualitatively in good agreement with the experimental results but predict this state to be unoccupied. Additionally, they reveal a splitting of the surface state into two energetically nearly degenerate components that is caused by symmetric and antisymmetric linear combinations of d_z² and p_z orbitals. No direct hints to interferences with the Kondo-resonance are obtained experimentally. On the other hand, the 4f hybridization is found to be substancially decreased at the surface. Analysis of a respective surface-induced 4f-dehybridization of α-Ce in the framework of the single-impurity Anderson model shows that in contrast to the α-γ phase transition in the bulk surface dehybridization is predominantly due to surface energy shifts of the 4f-states and not due to a decrease of the hybridization parameter. This could be taken as an indication for finite interactions of the 4f-states with the surface state.