Valence fluctuations of europium in the boride Eu4Pd29+xB8


Valence fluctuations of europium in the boride Eu4Pd29+xB8

Gumeniuk, R.; Schnelle, W.; Ahmida, M.; Abd-Elmeguid, M.; Kvashnina, K.; Tsirlin, A.; Leithe-Jasper, A.; Geibel, C.

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.

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Publ.-Id: 23003