Low Temperature Properties of the Ce1 - xLaxNiAl4

T. Tolińskia, A. Kowalczyka, M. Reiffersb, c, J. Šebekd, E. Šantavád, I. Curlikb and S. Ilkoviče aInstitute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland bInstitute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice, Slovakia cFaculty of Sciences, University of Prešov, 17 novembra, SK-080 78 Prešov, Slovakia dInstitute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Praha 8, Czech Republic eFaculty of Humanities and Natural Sciences, University of Prešov, 080 78 Prešov, Slovakia

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Measurements of the heat capacity in ultralow temperatures (down to 350 mK) have been carried out for Ce1 - xLaxNiAl4. The paramagnetic behavior above about 30 K can be well described by the Curie-Weiss magnetic susceptibility. The undoped CeNiAl4 compound is a known heavy fermion system with a large electronic specific heat coefficient (γ = 0.5 J mol-1 K-2) and the Kondo temperature in the range 30-80 K. In the case of the Ce0.8La0.2NiAl4 and Ce0.6La0.4NiAl4 compounds a peak in C/T appears below 2 K, which is strongly damped by the magnetic field. It is probably connected with the Kondo and/or magnetic interactions and the electronic specific heat coefficient is 0.19 J mol-1 K-2 (0.43 J mol-1 K-2) for x = 0.2 (x = 0.4) at T → 0. The value determined above the peak, at temperature for which the magnetic field starts to decrease γ ( ≈ 3 K), is about 0.5 J mol-1 K-2 and the effect of the magnetic field can be well analyzed in frames of the single-ion Kondo model.

DOI: 10.12693/APhysPolA.118.933 PACS numbers: 71.27.+a, 65.40.Ba, 75.30.Mb