Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.56: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Boron-induced change of valence state of Eu and structural phase transition in EuPd3Bx (0 ≤ x ≤ 0.55) — •Roman Gumeniuk, Claire Loison, Walter Schnelle, Wilder Carrillo-Cabrera, Paul Simon, Ulrich Burkhardt, Marcus Schmidt, Miriam Schmitt, Ulrich Schwarz, Helge Rosner, and Andreas Leithe-Jasper — MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany
A detailed experimental and theoretical study of the solubility of B in EuPd3 (AuCu3 structure type) and its influence on the physical properties is presented. Theoretical calculations (LDA + U + CPA method) predict in EuPd3Bx a change of non-magnetic 4f6 Eu to magnetic 4f7 Eu for a x > 0.2 together with an anomaly in the unit cell volume. At 950 ∘C the incorporation of B in EuPd3Bx is possible up to x = 0.55, as can be concluded from the lattice parameters, WDXS and chemical analyses. Transmission electron microscopy investigations show the existence of a superstructure for Eu2Pd6By in the region of 0.7 ≤ y ≤ 1 (Ti2Rh6B structure type [1], space group Fm3m, a = 8.3096(2)-8.3730(2) Å). From Eu LIII XAS studies as well as from magnetic susceptibility data it can be deduced that the Eu species in EuPd3 and in EuPd3Bx (0 ≤ x ≤ 0.2) exhibit a 4f6 state, while for EuPd3Bx (0.2 ≤ x ≤ 0.35) and Eu2Pd6By (0.7 ≤ y ≤ 1) they are in an intermediate valence state. Our findings are discussed with respect to previously published studies [2,3].
[1] B. Fowka et al. Z. Krist. 221 (2006) 445.
[2] B. Darshan et al. Phys. Rev. B, 30 (1984) 4031.
[3] S.K. Dhar et al. Phys. Rev. B, 29 (1984) 5953.