Quantum phases in spin-1 honeycomb antiferromagnets: application to Ni₂Mo₃O₈

Ni₂Mo₃O₈ is a recently synthesized material containing spin-1 moments on a honeycomb lattice [1]. Such systems are of interest due to their potential to exhibit topological magnons. According to the recent neutron scattering experiment [1], the two sub-lattices making up the bipartite honeycomb lattice each display a zig-zag antiferromagnetic order. Moreover, the order is non-coplanar with a non-trivial angle between adjacent spins due to competing interactions. In this work, we attempt to explain this spin ordering by the means of mean-field theory and Density Matrix Renormalization Group (DMRG) calculations. We use ab initio Density Functional Theory (DFT) calculations to extract the spin-exchange coefficients in the effective low-energy model. We propose that the Dzyaloshinskii-Moriya interaction is the most natural way to explain the observed magnetic ordering.

[1] J. R. Morey, et al. "Ni₂Mo₃O₈: zig-zag antiferromagnetic order an integer spin non-centrosymmetric honeycomb lattice", arXiv:1804.04776.