Thermal conductivity of the "light" heavy-fermion compound YbIn0.7Ag0.3Cu4

This paper reports on the electrical resistivity and thermal conductivity o f polycrystalline YbIn0.7Ag0.3Cu4 at temperatures from 4.2 to 300 K, which exhibits, at T-v, a continuous isostructural first-order phase transition f rom a Curie-Weiss paramagnet with localized magnetic moments (for T > T-v) to a Pauli paramagnet in a nonmagnetic Fermi liquid state with the Yb ion i n a mixed valence state (for T < T-v). It is shown that for T < T-v, the Lo renz number behaves in accordance with the theoretical model developed for heavy-fermion materials, while for T > T-v, it acquires the value typical o f standard metals. (C) 2001 MAIK "Nauka/Interperiodica".