Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.18: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Thermal transport properties of YbRh2(Si1−xGex)2 at low temperatures — •Stefanie Hartmann, Adriana Sanchez, Silke Paschen, Octavio Trovarelli, Christoph Geibel, and Frank Steglich — MPI CPfS, Nöthnitzer Str. 40, 01187 Dresden
The heavy-fermion compound YbRh2Si2 orders antiferromagnetically at TN = 70 mK and reveals non-Fermi liquid behavior in the vicinity of a (magnetic-field induced) quantum critical point [1,2]. Here we present thermal transport properties of pure and 5% Ge-doped samples. The previously reported logarithmic temperature dependence of the electronic specific heat coefficient Cel/T between 0.3 and 10 K [2] is reflected in the thermal conductivity over temperature ratio κ/T. The electronic contribution of κ shows deviations from the predictions of the Wiedemann-Franz law based on calculations from resistivity measurements. Thus, the applicability of the WF law seems to be questionable. The logarithmic behavior of Cel(T)/T is also observed in the thermopower over temperature ratio S(T)/T as theoretically predicted by Paul et al. [3]. But below 2 K S/T exhibits a stronger than logarithmic divergence (No-dqupturnNo-dq) with decreasing temperature.
P. Gegenwart et al., PRL 89, 056402 (2002)
J. Custers et al., Nature 424, 524 (2003)
I. Paul and G. Kotliar, PRB 64, 184414 (2001)