Acoustic Attenuation in Kondo Lattice

Abstract

Many Cerium and Uranium based compounds (referred as heavy — Fermion compounds) exhibit number of unusual physical properties which are akin to those of the Kondo-lattice. Recently, the Kondo lattice model has been considered for understanding of the properties like pairing1, transport properties2 and electronic structure5. The electrical resistivity in Cerium compounds4 shows Kondo-like (ln(T/Tk)) decrease at high temperature and passes through maximum as the temperature is lowered below Kondo temperature Tk. Such a behaviour of electrical resistance can be understood within the Kondo lattice model2. At higher temperature (T > Tk), the interaction between f-states are negligible and the system can be viewed as a collection of incoherent Kondo impurities. At lower temperature (T<Tk) coherence develops between virtual bound states and the system shows the Kondo-lattice behaviour. In an ideal case, this results zero resistance at T = 0 K. The coherence of f-states should also affect any other physical property where the conduction electrons are predominantly involved One such property is the acoustic attenuation. In a recent observation5 a peak in absorption of longitudinal acoustic wave has been observed in UPt3 around 12 K. This has been interpreted in terms of narrow Kondo state near the Fermi level and assuming the absorption of acoustic energy is mainly due to heavy Fermions5. Here we examine the contribution of conduction electron to the attenuation and show that this contribution gives rise to a peak due to resonance state at Fermi level.