Investigation of Yb₂Pt₆Al₁₅single crystals: heavy fermion system with a large local moment degeneracy

Abstract

We grew single crystals of Yb2Pt6Al15 and investigated the magnetic properties of this compound by means of susceptibility χ(T), specific heat C(T), resistivity ρ (T) and thermoelectric power S(T) measurements. While all properties follow in general the behavior typical for Kondo-lattice systems, χ(T) and C(T)/T present broad maxima in the T range 17–35 K, which matches nicely the prediction of the Coqblin–Schrieffer model for J= 7/2. A large degeneracy of the local moment is also supported by a reduced Kadowaki–Woods ratio. Thus, the analysis of all investigated properties evidences Yb2Pt6Al15 to be a paramagnetic Kondo-lattice system with the whole J= 7/2 multiplet involved in the formation of the Kondo state, a Kondo temperature of the order of 60 K, and a heavy Fermi-liquid ground state with a Sommerfeld coefficient γ 0 = 0.33 J (mol-Yb)−1 K−2 corresponding to a mass enhancement of the order of 30.