高濃度近藤系化合物YbCu_<5-x>Ag_xの磁気的, 電気的性質 [in Japanese] Magnetic and Electrical Properties of a Dense Kondo System YbCu_<5-x>Ag_x [in Japanese]
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YbCu<SUB>4</SUB>Ag crystallizes in the cubic AuBe<SUB>5</SUB>-type structure where Yb is trivalent and shows dense Kondo behavior, while YbCu<SUB>5</SUB> is known to have the hexagonal CaCu<SUB>5</SUB>-type structure where Yb is in a nonmagnetic divalent state. In this study, a pseudo-binary system YbCu<SUB>5-x</SUB>Ag<SUB>x</SUB> was investigated. The powder Xray diffraction revealed that YbCu<SUB>5-x</SUB>Ag<SUB>x</SUB> has the cubic AuBe<SUB>5</SUB>-type structure in the range of 0.125≤x≤1.0, while both the cubic and the hexagonal phase exist for 0≤x≤0.1, which suggests YbCu<SUB>5</SUB> has also cubic AuBe<SUB>5</SUB>-type where Yb seems to be trivalent. Magnetic and transport properties show that YbCu<SUB>5-x</SUB>Ag<SUB>x</SUB> is a dense Kondo system in which Kondo-temperature T<SUB>K</SUB> decreases continuously with the decrease of Ag-concentration x, causing the enhancement of the zerotemperature susceptibility x(O), the T<SUP>2</SUP>-coefficient A of electrical resistivity and the Sommerfeld coefficient γ of specific heat. The γ value was found to be enhanced to as large as 460mJ/mo1K<SUP>2</SUP> in YbCu<SUB>4.875</SUB>Ag<SUB>0.125</SUB>. These results imply the cubic AuBe<SUB>5</SUB>-type YbCu<SUB>5</SUB> is a dense-Kondo or a heavy-fermion system, in which γ reaches to about 500mJ/molK<SUP>2</SUP>.
- J. Jpn. Soc. Powder Powder Metallurgy
J. Jpn. Soc. Powder Powder Metallurgy 43(8), 1030-1035, 1996-08-15
Japan Society of Powder and Powder Metallurgy