Electronic and magnetic properties of EuNi 2-δ Sb 2 structural variants

X-ray diffraction, magnetic susceptibility, magnetization, heat capacity and electrical resistivity results are reported for single crystals of two structural variants of EuNi Sb that crystallize in the CaBe Ge and ThCr Si -type structures. While the former occurs with a stoichiometric ratio, the latter exhibits a Ni site vacancy (δ = 0.36). Both systems exhibit similar magnetic behavior at elevated temperatures, where there is an isotropic Curie-Weiss temperature dependence that indicates an antiferromagnetic exchange interaction between divalent europium ions, although it is stronger for the CaBe Ge -variant. At low temperatures, the differing structural environments that surround the Eu ions result in distinct ordering behavior. The CaBe Ge -variant orders antiferromagnetically near T = 6.9 K and then undergoes a first order phase transition at T = 4.6 K. The ThCr Si -variant exhibits simpler behavior, with antiferromagnetic ordering at T = 5.6 K. For both compounds, an applied magnetic field suppresses the ordering temperatures and induce metamagnetic phase transitions, while applied pressure causes the ordering temperatures to increase. From these results, EuNi Sb emerges as a useful system in which to study the impact of structural variation on magnetism in a Eu-based metal.