Single crystal study of antiferromagnetic CePd3Al9

Abstract

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 (dCe–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 TN = 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 TN) 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 = ρ300 K/ρ0 = 1.3.