Crystal growth, crystal structure and anisotropic magnetic properties of KBaR(BO_3)_2 (R = Y, Gd, Tb, Dy, Ho, Tm, Yb and Lu) triangular lattice materials

摘要

Crystals of the KBaR(BO3)(2) (R= Y, Gd, Tb, Dy, Ho, Tm, Yb and Lu) rare earth borates were grown by spontaneous nucleation from a KF-B2O3 flux. The crystals obtained were typically well-developed hexagonal plates about 1 mm in large dimension. The crystals were used to study the anisotropic temperature and field dependent magnetization of the materials, which are based on ideal triangular planes of magnetic rare earths. All structures were refined in space group R3m by single-crystal X-ray diffraction, and in addition to the equilateral triangular rare earth plane lattice, displayed K/Ba site occupancy disorder. All magnetic compounds reveal dominantly antiferromagnetic spin interactions with no magnetic ordering above 1.8 K. With the exception of KBaGd(BO3)(2), magnetic anisotropy was observed for other five magnetic members of the family. The results suggest that KBaR (BO3)(2) crystals may be of further interest for investigating the magnetic properties of rare earth ions on a triangular lattice.