Magnetic properties of layered rare-earth oxy-carbonates Ln2O2CO3 (Ln=Nd, Sm, and Dy)

Polycrystalline samples of rare-earth oxy-carbonates Ln2O2CO3 (Ln=Nd, Sm, and Dy) are synthesized and their structural and magnetic properties are investigated. All of them crystallize in a hexagonal structure with space group P63/mmc. They form a double layered structure with frustrated triangular arrangement of rare-earth magnetic ions. An antiferromagnetic transition is observed at TN~1.25K,0.61K, and 1.21 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. From the analysis of magnetic susceptibility, the value of the Curie-Weiss temperature θCW is obtained to be ~21.7 K, 18 K, and 10.6 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. The magnetic frustration parameter f(=|θCW|/TN) is calculated to be ~17.4, 31, and 8.8 for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively, which indicates that Sm2O2CO3 is strongly frustrated compared to its Nd and Dy analogues.