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Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.3: Poster

Thursday, March 29, 2012, 15:00–19:00, Poster B

Thermoelectric transport in Ce1−xLaxNi2Ge2 — •Ulrike Stockert1, Adam P. Pikul2, Nubia Caroca-Canales1, Stefanie Hartmann1, Christoph Geibel1, and Frank Steglich11MPI for Chemical Physics of Solids, 01187 Dresden, Germany — 2Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland

Investigations of the thermoelectric power S provide a sensitive probe of low energy excitations in metallic systems. In Ce-based heavy-fermion systems, Kondo interaction and crystal electric field (CEF) excitations usually give rise to large positive anomalies in S(T).

We performed thermopower and resistivity measurements on the diluted heavy fermion system Ce1−xLaxNi2Ge2 between 2 K and 300 K. In this temperature range the Kondo interaction as well as CEF excitations of the Ce3+ moments play a major role in the transport and scattering processes of the system. Our thermopower measurements reveal a reduction of the Kondo energy scale from about 30 K to 2 K with decreasing Ce concentration x, while the CEF levels remain almost unchanged. Simultaneously, the crossover from coherent to impurity scattering is observed in the resistivity ρ (T). Interestingly, ρ (T) varies smoothly upon Ce-La substitution, while S(T) changes rather abruptly for high Ce concentrations x≥ 0.9. We discuss our findings in comparison to recent specific heat measurements on the system.

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