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

TL;DR

This paper investigates deviations from the Kadowaki-Woods relation in Yb-based intermediate-valent systems, revealing many compounds have significantly smaller A/γ^2 ratios linked to weak magnetic correlations and degenerate ground states.

Contribution

It identifies and analyzes deviations from the Kadowaki-Woods relation in Yb compounds, highlighting the influence of magnetic correlations and ground state degeneracy.

Findings

Many Yb compounds have A/γ^2 ratios smaller than the Kadowaki-Woods value.

Smaller A/γ^2 ratios correlate with weak intersite magnetic correlations.

Compounds with nearly degenerate ground states tend to deviate from the relation.

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.