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

Abstract

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