Pressure dependence of the electrical resistivity of the filled skutterudites LnFe₄Sb₁₂ (Ln = Ce, Yb)

We report the pressure dependence of the electrical resistivity of two filled skutterudite compounds YbFe₄ Sb₁₂and CeFe₄ Sb₁₂from 1.2 K up to room temperature and under applied pressures up to 17 kbar. Both YbFe₄ Sb₁₂and CeFe₄ Sb₁₂show a rapid decrease of at ~50 K and ~100 K, respectively, which is caused by the onset of coherent scattering of electrons from the rare-earth sublattice. The resistivity curves can be collapsed onto the ambient pressure curve using a single scaling temperature T₀ , indicating that a single characteristic energy dominates the transport properties. For CeFe₄ Sb₁₂ , T₀is found to increase with pressure, while the opposite behaviour is observed for YbFe₄ Sb₁₂ . The pressure dependence of as well as the change of T₀are similar to the findings for a number of other intermediate-valence and heavy-fermion systems.