Specific heat of Ce1−xLaxNiAl4 compounds

The temperature dependence of the specific heat Cp(T) for the solid solution Ce1−xLaxNiAl4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) has been studied. The effective magnetic moment values obtained across the series are in far agreement with the value of 2.54 μB/Ce that corresponds to a free Ce3+ ion. The specific heat has been analyzed considering the electronic, phonon and Schottky contributions. In comparison to CeNiAl4, the substitution of Ce by La drastically reduces the values of the electronic specific heat coefficient γ. At low temperatures the γ value depends strongly on the temperature range used for the extrapolation and on the magnetic field. The scheme of the energy levels created by the splitting due to the crystal field (CEF) has been determined from the Schottky anomaly and is different for all compositions. The logarithmic dependence of the specific heat, Cp/T ∝ −lnT, on temperature indicates on the possibility of the non-Fermi liquid behavior for Ce0.8La0.2NiAl4 and Ce0.6La0.4NiAl4.

► The γ coefficient decreases with increasing La concentration, indicating a decrease in the density of states at the Fermi level.
► The magnetic part of specific heat analysis indicates that the crystal field parameters are dependent on the La concentration.
► The Kondo temperature estimated from the temperature dependence of the magnetic entropy, decreases with an increase of the unit cell volume and the La concentration.
► At low temperatures, the Cmag/T for x = 0.2 and 0.4 shows a logarithmic behaviour.