Pure and Yb-site partially substituted by Y, Lu and Zr samples of YbInCu4 were synthesized. Temperature dependence of magnetic susceptibility from 2 to 300 K under 0.5 T and high field magnetization up to 41 T at 4.2 K were measured. We found that both transition temperature (Tv) and transition magnetic field (Hv) of YbInCu4 are shifted to lower temperatures and lower magnetic fields by Y or Lu substitution, while they are increased by Zr substitution. The chemical pressure effect and dense Kondo interaction are discussed as factors to influence the valence transition of YbInCu4.

Temperature and magnetic field variations of the electric resistivitiy (ρ) as well as temperature dependence of the magnetic susceptibility (χ) are reported for the YbCu5−xAux system with the C15b-type structure. These results indicate a systematic composition dependence from dense Kondo to RKKY antiferromagnetic system via quantum critical point with x=0.2–0.4. The logarithmic temperature dependence of ρ was observed in the middle temperature range for all the compositions, implying that the incoherent Kondo scattering is dominant in this T-region. With decreasing temperature, the ρ tends to saturate, makes a maximum, then decreases toward the Fermi liquid ground state due to the coherent dense Kondo effect (x<0.2), or toward the antiferromagnetic ground state due to the RKKY interaction (for x>0.4). The non-Fermi liquid behavior was observed around the quantum critical composition (x=0.2–0.4).

The ThCr2Si2-type layered compound SrCo2P2 shows an itinerant-electron metamagnetic transition at high magnetic field. To investigate substitution effects on the itinerant metamagnetic transition, we synthesized Sr1-xLaxCo2P2 and SrCo2(P1-xGex)2 and measured their magnetic properties, including magnetizations under pulsed high magnetic fields. We have revealed a strong x dependence of the metamagnetic transition which is consistent with the band theory describing the physical properties in metals.