Magnetic and Thermodynamic Properties of Ce₄RuAl

The results of magnetic susceptibility and heat capacity measurements are reported for the Ce₄RuAl compound above room temperature to low temperature range (400 K to 0.34 K) and in the magnetic field up to 7 T. The magnetic susceptibility χ(T) exhibits a distinct anomaly at 0.95 K which most probably suggests a paramagnetic to antiferromagnetic phase transition. The magnetic susceptibility obeys the Curie-Weiss law in the region 100-400 K and revealed an effective magnetic moment $μ_{eff}$=2.18 $μ_{B}$/Ce which is less than the value for free Ce³⁺ ($μ_{eff}$=2.54 $μ_{B}$). The paramagnetic Weiss temperature indicates net antiferromagnetic correlations. In the specific heat a peak at 1.3 K supports the bulk nature of the phase transition observed in χ(T). The Sommerfield coefficient is moderately enhanced in the paramagnetic phase, and suggests f-c correlations among the electrons prior to magnetic ordering. The obtained Sommerfield coefficient γ behavior is consistent with the Anderson model-based theoretical predictions