Pomeranchuk effect in unstable Ytterbium systems

Abstract

$YbInC{u}_4$ and its alloys present discontinuous, first order iso-structural transitions at pressure dependent temperatures $T_V(P)$, where a local moment phase coexist with a renormalized Fermi liquid phase. We show that along the coexistence line $T_V(P)$ the entropy of the large volume renormalized Fermi liquid phase is smaller than that of the higher density, local moment phase. This implies the existence of a Pomeranchuk effect in these Kondo lattice materials in analogy with ${}^{3}He$. The theoretical possibility of using these systems as cooling machines is discussed.

3 pages, 3 figures and 1 table