Takeo Satoh

Ferromagnetic dense Kondo behavior of Ce-Si system

Abstract In order to clarify the nonmagnetic-magnetic transition found in Ce-Si system, magnetization measurements have been made to reveal a large reduction of the magnetic moment of Ce atom. Taking into account the results and also the reduction of the magnetic entropy, we propose a dense Kondo model to interpret our Ce-Si system. Kondo temperatures are deduced from various physical quantities and a comparison is made between them. Our Ce-Si system is the first example of a ferromagnetic dense Kondo system.

Nonmagnetic-magnetic transition in CeSi system

Abstract In order to clarify the intermediate valence state found in CeSi 2.00 , investigations have been made on CeSi x (2.00≥×≥1.55). In the composition range 2.00≥×≥1.85, Ce is in the intermediate valence state. For x ≤1.80 the system undergoes a sharp magnetic transition. The transient behavior of the magnetic susceptibility, the specific heat and those parameters deduced from these measurements will be discussed.

Thermal and magnetic properties and crystal structures of CeGe2 and CeSi2

Abstract In continuation of our investigation of α-ThSi 2 type rare earth intermetallic compounds, studies on CeSi 2 and CeGe 2 are reported. The results suggest that Ce in CeSi 2 is in the intermediate valence state. The existence or non-existence of superlattice structures are also discussed.

Spin-fluctuation effects in Ce-Si system

Abstract Discussions are presented for the Ce-Si system within the framework of the paramagnon model. Data of both the specific heat and the magnetic susceptibility are examined. There are indications that the predictions of the theory manifest themselves in the present system, although there are unfavorable aspects also.

THE SPECIFIC HEAT AND SUPERCONDUCTIVITY OF La--Y ALLOYS.

The low temperature specific heats of La-Y alloys have been measured in order to investigate the origin of superconductivity in lanthanum. The addition of yttrium to lanthanum was found to result in a large decrease of the electronic specific heat coefficient γ, a decrease in the superconducting transition temperature T c and a gradual increase of the Debye temperature \(\varTheta_{D}\). The rate of increase of \(\varTheta_{D}\) in the yttrium-rich hcp phase was observed to be appreciably larger than in the α-La phase. The effective interaction derived from the BCS formula was found to remain approximately constant in the α-La phase followed by a rapid decrease in the hcp phase. From the general trend of the measured and derived quantities with alloying, it is suggested that the superconductivity of lanthanum may be closely related to mechanism leading to the depression of the Debye temperature and the stabilization of the α-La structure. This implies that phonon processes are of importance in the enhance...

Heavy hole state in CeSb

Abstract We have measured the dHvA effect of CeSb down to 50 mK and discovered the largest hole Fermi surface, β 4 . The relative large electronic specific heat coefficient of CeSb compared with that of LaSb has been observed. These results are interpreted by the band calculation based on the p-f mixing model.

Thermal, electrical and magnetic properties of the ferromagnetic dense Kondo system CeSix

Single crystals of the ferromagnetic dense Kondo system CeSi x were grown, and the specific heat, the electrical resistivity and the magnetic susceptibility were measured. Electrical resistivity measurements clearly show the typical Kondo behavior, which unambiguously tells that CeSi x is a ferromagnetic dense Kondo system. The appreciable anisotropy of the magnetic susceptibility is analyzed with the crystalline field effect and a conjecture is made that the ground doublet is a \(\varGamma_{7}\)-like doublet.

Anisotropy and dense Kondo effect in CeRh3B2

Abstract The compound CeRh 3 B 2 shows strong anisotropy both in transport and magnetic properties, but no apparent anomaly characteristic of Kondo effect was observed. Ce 3d core-level photoemission of CeRh 3 B 2 and electrical resistivity of Ce 0.05 La 0.95 Rh 3 B 2 revealed that CeRh 3 B 2 is a dense Kondo lattice, Kondo effect being masked by strong interatomic exchange interaction.

Evidence for Magnetic Ordering in the Heavy-Electron Compound CeCu2In

Specific-heat and Cu NMR measurements have been made on the recently discovered heavy-electron compound CeCu 2 In. The low-temperature specific heat has an enormous electronic contribution with C el / T ≃1.2 J/mole·K 2 below 1.2 K, and shows a broad maximum at around 2.2 K. Below 2.3 K, Cu NMR linewidth Δ H shows appreciable additional broadening, and the nuclear transverse relaxation also becomes appreciably slower. These results indicate that CeCu 2 In undergoes an antiferromagnetic phase transition at T N ≃2.3 K. The possibility of ordering of quite a small moment is suggested from the observations of the gigantic value of C el / T below T N , the small magnetic entropy at T N , and the steady increase of C el / T through T N with decreasing temperature.

Magnetic and nonmagnetic behavior of the Ce-Si system

Abstract Systematic investigations on α-ThSi 2 type CeSi x (1.55≤ x ≤2.00) were made. The system undergoes a nonmagnetic-magnetic transition at around x =1.83. Magnetic and thermal properties of the system suggest that this is the first example of a ferromagnetic dense Kondo system. Effects of dilution of Ce with La are also discussed.