Magnetism in the KBaRE(BO3)2 (RE=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)   series: materials with a triangular rare earth lattice
  We report the magnetic properties of compounds in the KBaRE(BO3)2 family (RE= Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), materials with a planar triangular lattice composed of rare earth ions. The samples were analyzed by x-ray diffraction and crystallize in the space group R-3m. Physical property measurements indicate the compounds display predominantly antiferromagnetic interactions between spins without any signs of magnetic ordering above 1.8 K. The ideal 2D rare earth triangular layers in this structure type make it a potential model system for investigating magnetic frustration in rare-earth-based materials. 
M. B. Sanders, F. A. Cevallos, R. J. Cava
cond-mat.str-el