Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 43: Correlated Electrons: f-Electron & Heavy Fermion Systems
TT 43.5: Vortrag
Mittwoch, 9. März 2016, 10:30–10:45, H20
Valence fluctuations in the boride Eu4Pd29+xB8 — •Roman Gumeniuk1, Walter Schnelle2, Mahmoud Ahmida3, Mohsen Abd-Elmeguid3, Kristina Kvashnina4, Alexander Tsirlin2, Andreas Leithe-Jasper2, and Christoph Geibel2 — 1Institut für Experimentelle Physik, TU Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg, Germany — 2Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden, Germany — 3Universität zu Köln, II. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany — 4ESRF, 71, Avenue des Martyrs, Grenoble France
We synthesized a high quality sample of the boride Eu4Pd29+xB8 (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 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.