Effect of impurity phases on the anisotropic transport properties of CeNiSn

Nakamoto, G.; Takabatake, Toshiro; Bandô, Yoshio; Fujii, H.; Izawa, K.; Suzuki, Takashi; Fujita, Toshizo; Minami, Asao; Oguro, I.; Tai, L.T.; Menovsky, A.A.

doi:10.1016/0921-4526(94)00602-r

Cited by 57 publications

(26 citation statements)

References 7 publications

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“…(2) [18], which is also supported from the results of the Hall coefficient measurements [38], and proposed that this phenomenon is ascribed to an opening of the pseudogap caused by the short-range order of SDW below 100 K [19]. We also note that such a reduction of T/S below a pseudogap temperature is observed in other layered cobalt oxide [39] and the Kondo semiconductor CeNiSn [40]. We then discuss how the Rh substitution affects the pseudogap behavior.…”

Section: Discussionsupporting

confidence: 69%

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Ikeda

Saito

Okazaki

2016

Journal of Applied Physics

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We have examined an isovalent Rh substitution effect on the transport properties of the thermoelectric oxide Ca 3 Co 4 O 9 using single-crystalline form. With increasing Rh content x, both the electrical resistivity and the Seebeck coefficient change systematically up to x = 0.6 for Ca 3 Co 4−x Rh x O 9 samples. In the Fermi-liquid regime where the resistivity behaves as ρ = ρ 0 + AT 2 around 120 K, the A value decreases with increasing Rh content, indicating that the correlation effect is weakened by Rh 4d electrons with extended orbitals. We find that, in contrast to such a weak correlation effect observed in the resistivity of Rh-substituted samples, the low-temperature Seebeck coefficient is increased with increasing Rh content, which is explained with a possible enhancement of a pseudogap associated with the short-range order of spin density wave. In high-temperature range above room temperature, we show that the resistivity is largely suppressed by Rh substitution while the Seebeck coefficient becomes almost temperature-independent, leading to a significant improvement of the power factor in Rh-substituted samples. This result is also discussed in terms of the differences in the orbital size and the associated spin state between Co 3d and Rh 4d electrons.

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Section: Discussionsupporting

confidence: 69%

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Ikeda

Saito

Okazaki

2016

Journal of Applied Physics

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“…Unlike the resistivity data whose low-temperature anomaly is much affected by sample quality, it was previously shown that the low-temperature features in thermopower are not so sensitive to the quality of single crystals. 4 With these previous interpretations and results in mind, we therefore can rule out the possibility that what we observe in thermopower with small U doping is due to impurity effects. In searching for explanations for the disappearance of the peak by small U doping, we conclude that there is a sudden change by doping in the density of states very near the Fermi surface, probably in the region of F Ϯ10 K. Whether the substitution of 1.6% U leads to a complete collapse of the low-temperature partial gap structure in CeNiSn is difficult to tell.…”

Section: Thermopowersupporting

confidence: 49%

“…3 Interestingly enough, it was shown recently that the lowtemperature increase in the resistivity is very sensitive to the amount of impurities present in the samples: the more pure the sample the less distinct the resistivity increase is at low temperatures and it eventually becomes metallic. 4 Nevertheless, it seems that a small amount of impurities does not affect the gap opening behavior in general.…”

Section: Introductionmentioning

confidence: 99%

U doping effects in(Ce1−xUx)NiSn

1998

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We have studied (Ce 1Ϫx U x )NiSn for 0рxр0.2 to investigate the effects of U doping on the lowtemperature anomalies seen in CeNiSn. From resistivity and thermopower results, we conclude that with as small as 1.6% U doping the anomalies disappear. With further increasing U concentrations, the system becomes unstable towards a weakly antiferromagnetic transition. We discuss the effects due to small U doping at low temperatures in the light of chemical pressure effects and Fermi-level tuning. ͓S0163-1829͑98͒03021-5͔

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“…All these discrepancies are most probably related to the differences in sample quality. As mentioned above, none of the single crystals on which S(T) measurements were reported so far 6,14,[16][17][18] was purified by the SSE technique but, as was shown by Nakamoto et al, 14 this treatment is crucial for improving the sample quality. The SSE-treated samples investigated here have by far the lowest resistivity at 2 K and are the only ones with a positive slope d/dT at 2 K, clear indications for the highest sample quality.…”

Section: Resultsmentioning

confidence: 99%

Thermal-transport properties of CeNiSn

et al. 2000

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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.

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Effect of impurity phases on the anisotropic transport properties of CeNiSn

Cited by 57 publications

References 7 publications

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

U doping effects in(Ce1−xUx)NiSn

Thermal-transport properties of CeNiSn

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