Crystal Growth, Structure, and Magnetism of the 2D Spin ¹/₂ Triangular Lattice Material Rb₃Yb(PO₄)₂

The single-crystal growth, crystal structure, heat capacity, and anisotropic magnetization characterization of Rb3Yb(PO4)2, a Yb-based triangular lattice material, are presented. Single-crystal X-ray diffraction shows that Rb3Yb(PO4)2 exhibits [Yb(PO4)]∞ layers, with the Yb in an ordered plane of equilateral triangles. One phosphate group oxygen that is not a near neighbor of the magnetic Yb displays positional disorder. The temperature-dependent magnetization is anisotropic, with no long-range magnetic ordering observed for temperatures down to 50 mK. The low temperature heat capacity in the presence of an applied magnetic field is fitted very well by a Schottky anomaly with a linear magnetic-field-dependent gap between the ground and excited state energies. At 1.8 K, no magnetic transitions are seen for applied fields up to 90 kOe. Our results suggest that Rb3Yb(PO4)2 is a good candidate for displaying frustrated magnetism at low temperatures.