Magnetic properties of new layered compounds LaM1/3Sb5/3O6, M = Co, Ni, and Cu, with a honeycomb structure.

New compounds with the rosiaite type structure LaM_1/3Sb_5/3O₆, M = Co, Ni, and Cu, were synthesized. The compounds belong to quasi-two-dimensional magnets, in which magnetic interactions occur in the layers with a honeycomb structure. It is shown that there is no long-range magnetic order in these compounds. The temperature and field dependences of the magnetization in the compounds with M = Co, Ni indicate the presence of short-range anti-ferromagnetic and ferromagnetic exchange interactions. In the LaM_1/3Sb_5/3O₆, M = Co, Ni, compounds, the interactions occur between Co²⁺ or Ni²⁺ ions of isolated magnetic clusters randomly distributed in the paramagnetic matrix in the chains of (M/Sb)O₆ octahedrons. These clusters have sizes comparable with the crystal cell size. The LaCu_1/3Sb_5/3O₆ compound is paramagnetic. [ABSTRACT FROM AUTHOR]