Abstract: We report on synthesis, crystal structure and physical properties of the isotypic compounds YbPdSn2 and EuPdSn2 crystallizing in the MgCuAl2-type structure. In both stannides a divalent state of respective rare earth element was found from analysis of the magnetic susceptibilities. Whereas in YbPdSn2 only weak paramagnetic behaviour is observed, in EuPdSn2 a long-range magnetic phase transition occurs at 12.5 K with complex magnetic behaviour evidenced by magnetic susceptibity and specific heat measurements. Under the influence of magnetic field, the magnetic behaviour was found to evolve from an antiferromagnetic to a ferromagnetic state as a consequence of a re-arrangement of magnetic moments.

Abstract: The physical properties of the very-heavy-fermion compound YbCu4Ni were characterized through structural, magnetic, thermal, and transport studies along nearly four decades of temperature ranging between 50 mK and 300 K. At high temperature, the crystal electric field level splitting was determined with Δ1(Γ6)=85K and Δ2(Γ8)≈200K, the latter being a quartet in this cubic symmetry. An effective magnetic moment μeff≈3μB is evaluated for the Γ7 ground state, while at high temperature the value for a Yb3+ ion is observed. At low temperature this compound shows the typical behavior of a magnetically frustrated system undergoing a change of regime at a characteristic temperature T∗≈200mK into of Fermi-liquid-type “plateau” of the specific heat: Cm/T|T→0 = const. The change in the temperature dependence of the specific heat coincides with a maximum and a discontinuity in respective inductive and dissipative components of the ac susceptibility. More details about the nature of this ground state are revealed by the specific heat behavior under applied magnetic field.