An investigation of the magnetic heat capacity of the heavy-fermion compound YbCu_4Ni up to 0.4 K is presented. The novel compound LuCu_4Ni, isotypic with YbCu_4Ni has been synthesized and characterized, and its heat capacity was measured in order to subtract the lattice contribution from the previously measured heat capacity data of YbCu_4Ni.
The results on the influence of magnetic field on the electrical resistivity ρ(T) of the heavy fermion YbCu_4Ni in the temperature range 0.4-300 K are presented. We have observed a Kondo-like behaviour below 10 K with a minimum in ρ(T) at about 60 K. An applied magnetic field depresses this behaviour, and a maximum in ρ(T) appears similarly to the maximum observed in heat capacity. The observed electrical magnetoresistance shows negative values in all applied magnetic fields and with increasing temperature its absolute magnitude increases. Moreover, we extended our previous susceptibility measurements up to high temperatures of 1000 K, in order to study possible mixed valence behaviour, which however was not observed.
We report on the synthesis, crystal structure determination, and magnetic susceptibility measurements of Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂. For all three compounds a divalent state of Eu ions was obtained from the fitting of the magnetic susceptibilities. At low temperatures Eu₃Pd₂Sn₂, EuPd₂Sn₄, and EuPdSn₂ order magnetically at 23, 12, and 13 K, respectively.
Heat capacity measurements performed on the new ternary compound YbCu_4Ni indicate for this compound strong electronic correlations with possible antiferromagnetic phase transition below 0.5 K. Susceptibility and magnetisation measurements above 2 K show no magnetic ordering.
Among the new discovered intermetallics in the Yb-Pd-Sn system, the cubic phase Yb₃Pd₄Sn₁₃, with a lattice parameter of 0.9743(5) nm, emerges as a new member of the R₃T₄Sn₁₃ family (R = rare earth element, T = transition metal) crystallizing in the Yb₃Rh₄Sn₁₃-structure type. The effective magnetic moment μ_{eff}=1.84 μ_{B}/Yb is strongly reduced. Moreover, measurements of magnetic properties, specific heat and resistivity indicate superconductivity below 2.4 K. This compound is found to exhibit a strongly enhanced electronic specific heat at low temperature from which we infer a possible low-lying magnetic phase transition or other source of magnetic entropy.
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