Regensburg 2000 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 1: Schwere Fermionen
TT 1.9: Vortrag
Montag, 27. März 2000, 12:00–12:15, H20
Thermal transport properties of CeNiSn — •Silke Paschen1, Bodo Wand1, Günter Sparn1, Frank Steglich1, and Toshiro Takabatake2 — 1MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 48, D - 01187 Dresden — 2Faculty of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan
We present thermal conductivity κ and thermopower S measurements on high–quality single crystalline CeNiSn along the three crystallographic axes a, b, and c in the temperature range between 100 mK and 7 K and in magnetic fields of up to 8 T. Both κ and S are highly anisotropic. Sa(T) has a pronounced maximum of approximately 50 µV/K at 4.2 K. κb(T) is dominated by a maximum at 3.8 K. Smaller enhancements in the same temperature region are also observed for κa and κc. A magnetic field of 8 T applied along the a axis, which is the easy axis of magnetization, strongly suppresses all these enhancements. Between 2 K and 600 mK,κi∝ T2, indicating dominant phonon–electron scattering. Below 300 mK, κi=kT with slopes k larger than estimated for the electronic thermal conductivity using the Wiedemann–Franz law. Thus, even at the lowest temperatures, κ appears to be phonon dominated. All this suggests that the above mentioned enhancements originate from the opening of an anisotropic pseudogap [1].
[1] M. Sera et al., Phys. Rev. B 55, 6421 (1997) and Refs. herein.