Synthesis and Characterizations of Two-Dimensional Rare-Earth Magnetic Compounds RE2O2CN2 (RE = Nd, Dy, Gd) with a Frustrated Triangular Spin–Lattice

We report the synthesis and magnetic properties of three rare-earth magnetic compounds RE₂O₂CN₂ (RE = Nd, Dy, Gd) with a frustrated triangular spin–lattice, as well as their thermal stability and Fourier transform infrared (FTIR) spectroscopy. The magnetic susceptibility results show paramagnetic behavior with no long-range order (LRO) down to 2 K in Nd₂O₂CN₂ and Dy₂O₂CN₂ due to spin frustration, which are further confirmed by the specific heat measurements, despite the large Curie–Weiss temperature for strong intralayer interaction through the RE–O–RE pathway (RE = Nd, Dy). While Gd₂O₂CN₂ with a large spin exhibits LRO at 2.7 K, which should be caused by the non-negligible interlayer interactions. The field-dependent magnetization curves show a linear increase up to 7 T for Nd₂O₂CN₂ and Gd₂O₂CN₂, which are far from their saturation. While the magnetization of Dy₂O₂CN₂ increases linearly below 3 T, then slowly increases to saturation, and the magnetization value is 6.62 μ_B at 7 T. Our work provides promising magnetic triangular lattice systems to further investigate frustration and quantum magnetism in rare-earth magnetic systems.