New heavy-fermion antiferromagnet UPd₂Cd₂₀

We succeeded in growing a new high quality single crystal of a ternary uranium compound UPd₂Cd₂₀. From the electrical resistivity, magnetization, magnetic susceptibility, and specific heat experiments, UPd₂Cd₂₀ is found to be an antiferromagnetic heavy-fermion compound with the Néel temperature = 5 K and exhibits the large electronic specific heat coefficient γ exceeding 500 mJ (K²• mol)^-1. This compound is the first one that exhibits the magnetic ordering with the magnetic moments of the U atom in a series of UT₂X₂₀ (T: transition metal, X = Al, Zn, Cd). UPd₂Cd₂₀ shows typical characteristic features in heavy-fermion systems such as a broad maximum in the magnetic susceptibility at and a large coefficient A of T ² term in the resistivity.