Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)
O 14.64: Poster
Monday, March 27, 2006, 18:00–21:00, P2
Energy dispersion of 4f-derived emissions in photoelectron spectra of the heavy-fermion compound YbIr2Si2 — •S. Danzenbächer1, Yu. Kucherenko2, C. Laubschat1, D.V. Vyalikh1, Z. Hossain3, Ch. Geibel3, N. Mannella4, X.J. Zhou4, W. Yang4, Z.-X. Shen4, and S.L. Molodtsov1 — 1Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany — 2Institute of Metal Physics, National Academy of Sciences of Ukraine, UA-03142 Kiev, Ukraine — 3Max Planck Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D-01187 Dresden, Germany — 4Stanford Synchrotron Radiation Laboratory and Department of Applied Physics, Stanford University, Stanford, California 94305, USA
In the present work we report on an angle-resolved PE study of the heavy-fermion system YbIr2Si2. Our experiments reveal YbIr2Si2 to be mixed-valent with a mean valency of 2.9 at a temperature of 15 K. At the outermost surface layer, Yb is found to be divalent with a 4f BE of about 0.5 eV. A parabolic band with hole-like dispersion around the Γ point is observed, that crosses the almost dispersion-free Yb 4f13 surface signal in the Brillouin zone. Around the intersection points the f emission splits into two dispersive components separated from each other by about 0.2 eV. In the region of the Γ point also the 4f13 bulk emission at EF reveals a similar k dependent splitting related to the interaction with parabolic bands of electron-like dispersion that cross EF close to the Γ point. The dispersion of the interacting 4f13 states is explained in terms of a simplified periodic Anderson model by a k dependence of the electron hopping matrix element.