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Unusual Non-Fermi Liquid Behavior of Ce$_{1-x}$La$_{x}$Ni$_{9}$Ge$_4$ Analyzed in a Single Impurity Anderson Model with Crystal Field Effects

E. -W. Scheidt·F. Mayr·U. Killer·W. Scherer·H. Michor·E. Bauer·S. Kehrein·Th. Pruschke·F. Anders
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Abstract

CeNi$_{9}$Ge$_4$ exhibits unusual non-Fermi liquid behavior with the largest ever recorded value of the electronic specific heat $ΔC/T \cong 5.5$ JK$^{-2}$mol$^{-1}$ without showing any evidence of magnetic order. Specific heat measurements show that the logarithmic increase of the Sommerfeld coefficient flattens off below 200 mK. In marked contrast, the local susceptibility $Δχ$ levels off well above 200 mK and already becomes constant below 1 K. Furthermore, the entropy reaches 2$R$ln2 below 20 K corresponding to a four level system. An analysis of $C$ and $χ$ was performed in terms of an $SU(N=4)$ single impurity Anderson model with additional crystal electric field (CEF) splitting. Numerical renormalization group calculations point to a possible consistent description of the different low temperature scales in $Δc$ and $Δχ$ stemming from the interplay of Kondo effect and crystal field splitting.

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E. -W. Scheidt, F. Mayr, U. Killer, W. Scherer, H. Michor, E. Bauer, S. Kehrein, Th. Pruschke, F. Anders. 2005-06-07. Unusual Non-Fermi Liquid Behavior of Ce$_{1-x}$La$_{x}$Ni$_{9}$Ge$_4$ Analyzed in a Single Impurity Anderson Model with Crystal Field Effects. https://doi.org/10.1016/j.physb.2006.01.263

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