Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 43: Correlated Electrons: f-Electron & Heavy Fermion Systems
TT 43.6: Vortrag
Mittwoch, 9. März 2016, 10:45–11:00, H20
Coexistence of magnetic order and valence fluctuations in a heavy fermion system Ce2Rh3Sn5. — •Monika Gamza1,2,4, Roman Gumeniuk3,2, Walter Schnelle2, Ulrich Burkhardt2, Andrzej Ślebarski4, and Helge Rosner2 — 1Jeremiah Horrocks Institute, University of Central Lancashire, Preston, UK — 2MPI CPfS, Dresden, Germany — 3Institute of Experimental Physics, Freiberg University of Mining and Technology, Freiberg, Germany — 4Institute of Physics, University of Silesia, Katowice, Poland
While most Ce-based intermetallics contain either trivalent or intermediate-valent Ce ions, only for a few compounds a coexistence of both species has been reported. Here, we present a combined experimental and theoretical study based on thermodynamic measurements and spectroscopic data together with ab-initio electronic structure calculations aiming at exploring magnetic properties of Ce ions in two nonequivalent sites in Ce2Rh3Sn5. Ce LIII XAS spectra give direct evidence for valence fluctuations. Magnetization measurements show an onset of an antiferromagnetic order at TN≈2.5 K. The electronic structure calculations suggest that the magnetic ordering is related only to one Ce sublattice. This is in-line with a small entropy associated with the magnetic transition Smag≈ 0.35 R ln2 per Ce atom as revealed by the specific heat measurement. Furthermore, the temperature dependence of the magnetic susceptibility can be well described assuming that there are fluctuating moments of Ce3+ ions in one sublattice, whereas Ce atoms from the second sublattice are in a nonmagnetic intermediate valence state.