|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1992 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1991 : ¥1,500,000 (Direct Cost : ¥1,500,000)
The Kondo compounds of cerium and samarium show very often the typical increase of resisitivity due to Kondo scattering at low temperatures. Some show a decrease of resistivity due to the onset of coherence of Kondo scattering or a heavy electron state, and some show a sudden and rapid decrease due to the onset of magnetic order at lower temperature. In addition, a sharp critical type resistivity peak is observed in some cases, at the onset of magnetic order. Moreover, some comounds like CeNiSn show a resistivity increase of a semiconductor type due to a gap formation of an origin of Kondo scattering. Thus, the resistivity behavior of Kondo compounds are of various types.However, the resistivity measurements alone can not tell the origin of its anomalies because of too much complications of similar effects. Our aim of present study is to systematically measure the thermopower in addition to the resistivity and to have an unified picture of the phenomena of Kondo compounds.
In this study, we have prepared a large number of new Ce compounds having a chemical formula CeTX (T=Ni, Pd or Pt, X=Sn, In or Ge) and measured their resistivity and thermopower. The results are full of variety showing characteristic and different nature of Kondo effect of each compound. We found a close relation of an initial slope of thermopower and the electronic specific heat at low temperature. We found some of typical types of thermopower behavior of Kondo compounds at the ferromagnetic Curie temperature or at the antiferromagnetic Neel temperature. However, as for Sm compounds, those we have studied mostly did not show Kondo effects. Further study must be carried out for Sm compounds.