title: k Dependence of the crystal-field splittings of 4f states in rare-earth systems.
abstract: The occupation, energy separation, and order of the crystal-field-split 4f states are crucial for the understanding of the magnetic properties of rare-earth systems. We provide the experimental evidence that crystal-field-split 4f states exhibit energy dispersion in momentum space leading to variations of energy spacings between them and even of their energy sequence across the Brillouin zone. These observations were made by performing angle-resolved photoemission experiments on YbRh(2)Si(2) and properly simulated within a simple model based on results obtained by inelastic neutron scattering experiments and band structure calculations. Our findings should be generally applicable to rare-earth systems and have considerable impact on the understanding of magnetism and related phenomena.
authors.affiliation: Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany.
authors.forename: D V
authors.initials: DV
authors.lastname: Vyalikh
authors.forename: S
authors.initials: S
authors.lastname: Danzenbächer
authors.forename: Yu
authors.initials: Y
authors.lastname: Kucherenko
authors.forename: K
authors.initials: K
authors.lastname: Kummer
authors.forename: C
authors.initials: C
authors.lastname: Krellner
authors.forename: C
authors.initials: C
authors.lastname: Geibel
authors.forename: M G
authors.initials: MG
authors.lastname: Holder
authors.forename: T K
authors.initials: TK
authors.lastname: Kim
authors.forename: C
authors.initials: C
authors.lastname: Laubschat
authors.forename: M
authors.initials: M
authors.lastname: Shi
authors.forename: L
authors.initials: L
authors.lastname: Patthey
authors.forename: R
authors.initials: R
authors.lastname: Follath
authors.forename: S L
authors.initials: SL
authors.lastname: Molodtsov