Unusual Single-Ion Non-Fermi-Liquid Behavior in Ce1-xLaxNi9Ge4

Abstract

We report on specific heat, magnetic susceptibility, and resistivity measurements on the compound Ce1−xLaxNi9Ge4 for various concentrations ranging from the stoichiometric system with x=0 to the dilute limit x=0.95. Our data reveal single-ion scaling with the Ce concentration and the largest ever recorded value of the electronic specific heat Δc/T≈5.5 J K−2 mol−1 at T=0.08 K for the stoichiometric compound x=0 without any trace of magnetic order. While in the doped samples Δc/T increases logarithmically below 3 K down to 50 mK, their magnetic susceptibility behaves Fermi-liquid-like below 1 K. These properties make the compound Ce1−xLaxNi9Ge4 a unique system on the borderline between Fermi-liquid and non-Fermi-liquid physics.