We report the physical properties of RCd3As3 (R = La and Ce) compounds, crystallized into a hexagonal ScAl3C3-type structure (P 63/mmc) such that the R sublattice forms a spin-orbit coupled triangular lattice. Magnetic susceptibility measurements indicate the 4f electrons of Ce 3+ ions are well localized and reveal a large magnetic anisotropy. The electrical resistivity and specific heat measurement for RCd3As3 exhibit an anomaly at high temperatures (T0 ∼ 63 K for R = La and T0 ∼ 136 K for R = Ce), most likely due to a structural transition. Specific heat measurements for CeCd3As3 clearly indicate a long range magnetic order below TN = 0.42 K. Although the magnetic contribution to the specific heat Cm/T increases significantly below ∼ 10 K, the electrical resistivity for CeCd3As3 follows typical, metallic behavior inconsistent with Kondo lattice systems. In CeCd3As3 only ∼ 40 % of the R ln(2) magnetic entropy is recovered by TN and the Rln(2) entropy is fully achieved at about the Curie-Weiss temperature |θp|. Unusually, based on our current investigations, the magnetic specific heat below |θp| is not attributed to a Kondo contribution, but rather associated with the magnetic ordering and frustration on the triangular lattice. Specific heat measurements in applied magnetic field show a negligible variation of TN for H c, whereas a suppression of TN is observed above 40 kOe for H ab. Such behavior is consistent with the application a magnetic field within the ab-plane breaking the triangular symmetry and partially relieving the magnetic frustration in this system.

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