A Family of Quasi-Two-Dimensional Honeycomb Lattice Magnets RE₂Te₄O₁₁ (RE = Gd–Er and Yb) with Large Interlayer Distances

Two-dimensional rare earth (RE)-based honeycomb lattice magnets provide a fertile platform for exploring exotic magnetic ground states in view of reduced spatial dimensionality and anisotropic exchange interactions, while the reported 2D honeycomb lattice materials are quite limited. Herein, we report a family of quasi-two-dimensional layered RE-based honeycomb lattice magnets RE₂Te₄O₁₁ (RE = Gd-Er and Yb), where the magnetic honeycomb layers are well separated by nonmagnetic TeO₄ polyhedra with large interlayer distances of 8.353-8.452 Å. Magnetic susceptibility characterizations reveal that all synthesized RE₂Te₄O₁₁ (RE = Gd-Er and Yb) compounds exhibit dominant antiferromagnetic (AFM) interactions; three RE₂Te₄O₁₁ (RE = Gd, Tb, and Dy) family members show magnetic transitions with Néel temperatures (<i>T</i>_N) of 1.97, 3.61, and 2.52 K, respectively. For Tb₂Te₄O₁₁, a field-induced spin-flop transition is observed below <i>T</i>_N = 3.61 K in the isothermal magnetization <i>M</i>(<i>B</i>) curves. Based on the analysis of the magnetocaloric effect (MCE), a crossover behavior is observed from the inverse MCE at low fields (Δ<i>B</i> < 1.8 T) to conventional MCE at high fields (Δ<i>B</i> > 1.8 T) below the <i>T</i>_N in Tb₂Te₄O₁₁; this is in contrast to the conventional MCE in all measured field regions in other RE₂Te₄O₁₁ compounds.