The two-dimensional metallic triangular lattice antiferromagnet CeCd3P3

Single crystals of $R$Cd${}_3$P${}_3$ ($R$ = La and Ce) have been investigated by magnetization, electrical resistivity, Hall coefficient, and specific heat. Magnetization measurements of CeCd${}_3$P${}_3$ demonstrate clear quasi-2D magnetic behavior. Electrical resistivity and Hall coefficient measurements suggest that $R$Cd${}_3$P${}_3$ compounds are low carrier density metallic systems, in strong contrast to an earlier study of polycrystalline material. Specific heat and electrical resistivity measurements of CeCd${}_3$P${}_3$ reveal a high temperature (structural) phase transition at $T_s=127$~K and antiferromagnetic ordering below $T_N=0.41$~K. Upon applying magnetic field in the easy-plane ($H\parallel ab$) the magnetic ordering temperature increases to 0.43~K at $H\sim 15$~kOe, demonstrating partial lifting of the magnetic frustration. The large electronic specific heat persists in an unusually wide range of temperature above $T_N$, due to the frustrated spins. The observation of conventional metallic behavior in the electrical resistivity suggests that the $f$-electrons in CeCd${}_3$P${}_3$ undergo negligible hybridization with the conduction electrons. Thus, CeCd${}_3$P${}_3$ may be a model system for exploring the complex interplay between magnetic frustration and RKKY physics on a low carrier density Ce triangular lattice.