Thermal-transport properties of CeNiSn

Abstract

We present thermal-conductivity 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 up to 8 T applied along the a axis. Both and S are highly anisotropic. However, characteristic features that may be attributed to the opening of a pseudogap in the electronic density of states ͑DOS͒ at the Fermi energy below 10 K are seen for all three crystallographic directions. These features are strongly suppressed by a magnetic field of 8 T applied along the a axis. At the lowest temperatures we have evidence for the presence of a residual metallic DOS at , again for all three directions. The saturation of the reduced Lorenz number L/L 0 to a value distinctly higher than one is an interesting feature which deserves further investigation.

Strongly correlated cage compounds for thermoelectric applications?

“…5. It may well be that the small and strongly temperature dependent thermopower, which changes sign twice, is strongly anisotropic as, e.g., observed for the orthorhombic compound CeNiSn [1] and the tetragonal compound U2Ru2Sn [20]. In this case the small magnitude of the thermopower might be due to a directional averaging effect.…”

“…This is generally refered to as the "phonon glass -electron crystal" concept (PGEC) [5]. It measured with the heat current along the crystallographic a-axis, reaches 46 ,uV/K slightly above 4 K (after Paschen et al [1]). der unity [6].…”

Magnetic and electron transport properties of single-crystal UPtGe

“…Finally, we want to mention that an analogue situation in the behavior of S(T) was also reported in the detailed work of Paschen et al 31 for single-crystalline CeNiSn, having characteristic features of the opening of a pseudogap in the DOS at E F , which drives the S i (T) through pronounced maxima at low temperatures. However, the reasons of a pseudogap arising in CeNiSn are not connected with the onset of a magnetic ordered state.…”

Field dependence of the thermopower of CeNiSn

“…Various experimental probes confirm the presence of a finite quasiparticle DOS at the Fermi level, such as the metal-like resistivities of samples with high purity [1] and the linear-in-T dependence of the thermal conductivity below 0.3 K [2]. Magnetic fields of the order of 10 T along the easy magnetic a axis suppress the gap formation significantly, while fields along b and c are less effective [2,3]. The thermopower S of CeNiSn is highly anisotropic and exhibits a significant sample dependence [2,4,5,6].…”

“…Introduction: The orthorhombic system CeNiSn has been classified as a Kondo semimetal, in which an anisotropic pseudogap opens in the density of states (DOS) below approximately 10 K [1]. Various experimental probes confirm the presence of a finite quasiparticle DOS at the Fermi level, such as the metal-like resistivities of samples with high purity [1] and the linear-in-T dependence of the thermal conductivity below 0.3 K [2]. Magnetic fields of the order of 10 T along the easy magnetic a axis suppress the gap formation significantly, while fields along b and c are less effective [2,3].…”