The magnetic honeycomb lattice series of compounds, AAg2(M'1/3M2/3)[VO4]2 with A = Ba(2+), Sr(2+), M' = Mg(2+), Zn(2+), and M = Mn(2+), Co(2+), and Ni(2+), have been synthesized and their physical properties are reported. This series of compounds contains the M' and M cations in a 1:2 ratio on a single crystallographic site. In an ordered arrangement, this could generate a magnetic honeycomb-type lattice. Presented X-ray diffraction data, spectroscopic measurements of lattice dynamics, along with ab initio calculations, magnetic, and specific heat data for these compounds clearly point toward the formation of magnetic honeycomb-type lattices.

The series of compounds, AAg 2 Cr[VO 4 ] 2 with A = Ag, K, or Rb, are layered S = 3/2 triangularlattice (TL) systems where the magnetic exchange interactions between Cr 3+ (3d 3 ) ions are mediated by non-magnetic [VO 4 ] 3− entities. Here, the relative orientation of the vanadate is altered with respect to the TL as a function of the A-site which corresponds to an induced symmetry change of the [CrO 6 ]-complex. All members of this series of compounds belong to the class of frustrated TL antiferromagnets. We find that the distorted TL (A = Ag) exhibits collinear antiferromagnetic long-range order (LRO) at T N ≈ 10 K, whereas the high-symmetry cases (A = K, Rb) evade LRO in zero field down to 0.03 K, the lowest temperature of our experiments. The latter members of the series belong to the undistorted TL and are candidates for spin-liquid ground states presumably not related to Ising anisotropy or dimerization.