Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.3: Poster

Donnerstag, 29. März 2012, 15:00–19:00, Poster B

Thermoelectric transport in Ce_1−xLa_xNi₂Ge₂ — •Ulrike Stockert¹, Adam P. Pikul², Nubia Caroca-Canales¹, Stefanie Hartmann¹, Christoph Geibel¹, and Frank Steglich¹ — ¹MPI 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 Ce_1−xLa_xNi₂Ge₂ 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.