Synthesis and frustrated magnetism of the triangular lattice <i>ARE</i>Se₂ single crystals

We have successfully synthesized ARESe₂ (A = Alkali metal, RE=rare-earth) single crystals by the salt flux. These crystals stabilize in either the trigonal (R-3m) or hexagonal (P6₃/mmc) crystal systems depending on the RE, containing the ideal triangular RE³⁺ layers. We have characterized them through magnetization and heat capacity down to 0.4 K. Antiferromagnetic interactions with large magnetic anisotropy is observed, while no long-range order is found indicating frustrated magnetism. Yb-based crystals present a two-peak feature in the heat capacity below 10 K, while the magnetic plateau is found at 4 T when the magnetic field is applied in the ab plane. The 112 system is found to be particularly interesting for the study of frustrated magnetism and its potential for quantum spin liquid behavior.