title: Valence fluctuations of europium in the boride Eu4Pd(29+x)B8.
abstract: We synthesized a high-quality sample of the boride Eu4Pd(29+x)B8 (x  =  0.76) and studied its structural and physical properties. Its tetragonal structure was solved by direct methods and confirmed to belong to the Eu4Pd29B8 type. All studied physical properties indicate a valence fluctuating Eu state, with a valence decreasing continuously from about 2.9 at 5 K to 2.7 at 300 K. Maxima in the T dependence of the susceptibility and thermopower at around 135 K and 120 K, respectively, indicate a valence fluctuation energy scale on the order of 300 K. Analysis of the magnetic susceptibility evidences some inconsistencies when using the ionic interconfigurational fluctuation (ICF) model, thus suggesting a stronger relevance of hybridization between 4f and valence electrons compared to standard valence-fluctuating Eu systems.
authors.affiliation: Institut für Experimentelle Physik, TU Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg, Germany. Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Gumeniuk
authors.forename: Walter
authors.initials: W
authors.lastname: Schnelle
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Ahmida
authors.forename: Mohsen M
authors.initials: MM
authors.lastname: Abd-Elmeguid
authors.forename: Kristina O
authors.initials: KO
authors.lastname: Kvashnina
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Tsirlin
authors.forename: Andreas
authors.initials: A
authors.lastname: Leithe-Jasper
authors.forename: Christoph
authors.initials: C
authors.lastname: Geibel