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 6.54: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Possible crystal electrical field shift in the system CeNi9−xCuxGe4. — •Ernst-Wilhelm Scheidt1, Ludwig Peyker1, Christian Gold1, Wolfgang Scherer1, Ernst Bauer2, Herwig Michor2, Tobias Unruh3, and Peter Link3 — 1Institut für Physik, Universität Augsburg, 86159 Augsburg, Germany — 2Institut für Festkörperphysik, TU Wien, 1040 Wien, Austria — 3Forschungsneutronenquelle Heinz Maier-Leibnitz, Technische Universität München, 85747 Garching, Germany
Crystal structure, specific heat, magnetic susceptibility, electrical resistivity and inelastic neutron studies on the heavy fermion system CeNi9−xCuxGe4 (0 ≤ x ≤ 1) reveal a continuous tuning of the ground state by Ni/Cu substitution from an effectively fourfold degenerate non-magnetic Kondo ground state of CeNi9Ge4 with pronounced non-Fermi-liquid (nFL) features towards a magnetically ordered, effectively twofold degenerate ground state in CeNi8CuGe4 with TN = 0.18 K. NFL behavior, C/T∝χ∝ -lnT and ρ ∝ T, is observed for x ≅ 0.4. Hitherto, this is the first example where a substitution driven quantum phase transition is connected not only with changes of the relative strength of Kondo effect and RKKY interaction, but also with a reduction of the effective crystal field ground state degeneracy.