Single crystal study of antiferromagnetic CePd3Al9.

Single crystal x-ray diffraction, magnetic susceptibility (M), heat capacity (C), and electrical resistivity (ρ) measurements are reported for specimens of the new tetragonal compound CePd3Al9, which forms in a new structure type. X-ray diffraction measurements reveal that the nearest neighbor Ce-Ce distances are large (d(Ce-Ce) = 5.272 Å), suggesting that this compound may be described as a stoichiometric dilute Kondo lattice. Thermodynamic and transport measurements reveal antiferromagnetic order near T(N) = 0.9 K. The ordered ground state emerges from a lattice of localized Ce ions that are weakly hybridized with the conduction electrons, as revealed by the moderate electronic coefficient of the specific heat γ ≈ 45 mJ mol(-1) K(-2) (extrapolated from above T(N)) and the lack of evidence for Kondo coherence in the magnetic susceptibility and electrical resistivity. The application of a magnetic field initially suppresses the magnetic order at a rate of -0.04 K kOe(-1), but Zeeman splitting of the doublet ground state produces a nonmagnetic singlet before TN reaches zero. The data additionally reveal that chemical/structural disorder plays an important role, as evidenced by results from single crystal x-ray diffraction, the broadness of the peak at TN in the heat capacity, and the small residual resistivity ratio RRR = ρ(300 K)/ρ0 = 1.3.