Deviation from the Kadowaki Woods relation in Yb-based intermediate-valence systems

The T^2 coefficient of electrical resistivity, A, is compared with the electronic specific-heat coefficient, γ, for a number of Yb-based compounds. It is revealed that many systems including YbCuAl, YbInCu4, YbAl3 and YbCu5 show A/γ^2 values close to 0.4*10⁻⁶ μΩ cm(mol K/mJ)^2, which is remarkably smaller than that known as the Kadowaki-Woods relation, A/γ^2 = 1.0*10⁻⁵ μΩ cm(mol K/mJ)^2. Empirically, the compounds with the smaller A/γ^2 values appear to show weak intersite magnetic-correlation and/or to have almost fully-degenerated (J = 5/2 or 7/2) ground states.