Composition Effect of Kondo Behavior in Au–Al–Ce Quasicrystalline Approximants

Abstract

We have studied the magnetic and transport properties of Tsai-type quasicrystalline approximants, Au_xAl_84−xCe₁₆ and Au_yAl_86−yCe₁₄ by the measurements of magnetic susceptibility χ, specific heat C_p and electrical resistivity ρ. A Curie-Weiss behavior in χ for all compounds indicates the stable trivalent state of Ce ions in Au–Al–Ce. The effective magnetic moment increases with increasing the Au concentration whereas the Weiss temperature decreases. These behaviors suggest the Kondo effect in Au–Al–Ce suppresses with the increase of Au concentration. In C_p, all measured compounds show a broad peak due to the Kondo resonance at 0.8 K. In addition, C_p/T shows a peak below 0.6 K, which implies the existence of spin-glass transition. In all compounds, a pronounced −log T behavior due to Kondo effect are observed in ρ(T) below 10 K. Moreover, Au_yAl_86−yCe₁₄ approximants are the first example displaying a precursor of coherent Kondo state at low temperatures because a broad maximum is observed in ρ(T) at 1.3 K.

Fig. 4 Electrical resistivity of (a) Au_xAl_84−xCe₁₆ and (b) Au_yAl_86−yCe₁₄.