Crossover from Single-Ion to Coherent Non-Fermi Liquid Behavior in Ce₁₋ₓLaₓNi₉Ge₄

الأصل · EN

We report specific heat and magneto-resistance studies on the compound Ce₁₋ₓLaₓNi₉Ge₄ for various concentrations over the entire stoichiometric range. Our data reveal single-ion scaling with Ce-concentration between x = 0.1 and 0.95. Furthermore, CeNi₉Ge₄ turns out to have the largest ever recorded value of the electronic specific heat Δc/T ≈ 5.5 J K⁻²mol⁻¹ at T=0.08 K which was found in Cerium f-electron lattice systems. In the doped samples Δc/T increases logarithmically in the temperature range between 3 K and 50 mK typical for non-Fermi liquid (nFl) behavior, while ρ exhibits a Kondo-like minimum around 30 K, followed by a single-ion local nFl behavior. In contrast to this, CeNi₉Ge₄ flattens out in Δc/T below 300 mK and displays a pronounced maximum in the resistivity curve at 1.5 K indicating a coherent heavy fermion groundstate. These properties render the compound Ce₁₋ₓLaₓNi₉Ge₄ a unique system on the borderline between Fermi liquid and nFl physics.