Kondo-lattice formation in cubic-phase YbCu{sub 5}

The YbCu{sub 5} phase with C15b structure has been prepared by a high-pressure technique, and its physical properties have been investigated. The temperature dependence of magnetic susceptibility, electrical resistivity, and specific heat show Kondo-lattice formation. Furthermore, a heavy Fermi-liquid state without magnetic ordering down to 2.0 K is found to evolve below about 6 K. The electronic specific heat coefficient {gamma} is enhanced to values as large as to 550 mJ/molthinspK{sup 2}. The magnetization measured up to 40 T at 1.6 K has a field dependence which is expected for a Kondo system when the total angular momentum is J{gt}1. All results are in good agreement with the extrapolation of the previous results of YbCu{sub 5{minus}x}Ag{sub x} (0.125{le}x{le}1.0) for x{r_arrow}0. The concentration dependence of characteristic temperatures of YbCu{sub 5{minus}x}Ag{sub x} can be quantitatively explained by the chemical pressure effect within the compressible Kondo model for the full range of Ag concentration ( 0.0{le}x{le}1.0). The origins of Kondo-lattice formation in YbCu{sub 4}Ag and the valence transition in YbCu{sub 4}In are discussed. {copyright} {ital 1997} {ital The American Physical Society}