The high temperature magnetic order in SrRu2O6 was studied by measuring magnetization and neutron powder diffraction with both polarized and unpolarized neutrons. SrRu2O6 crystallizes into the hexagonal lead antimonate (PbSb2O6, space group \textit{P}31\textit{m}) structure with layers of edge-sharing RuO6 octahedra separated by Sr2+ ions. SrRu2O6 orders at TN=565\,K with Ru moments coupled antiferromagnetically both in-plane and out-of-plane. The magnetic moment is 1.30(2) μB/Ru at room temperature and is along the crystallographic \textit{c}-axis in the G-type magnetic structure. We performed density functional calculations with constrained RPA to obtain the electronic structure and effective intra- and inter-orbital interaction parameters. The projected density of states show strong hybridization between Ru 4d and O 2p. By downfolding to the target t2g bands we extracted the effective magnetic Hamiltonian. We performed Monte Carlo simulations to determine the transition temperature as a function of inter- and intra-plane couplings and find weak inter plane coupling, 3\% of the intra-plane coupling, permits three dimensional magnetic order at TN. As suggested by the magnetic susceptibility, two-dimensional correlations persist above TN due to the strong intra-plane coupling.
@article{arxiv.1504.03642,
title = {High antiferromagnetic transition temperature of a honeycomb compound SrRu$_2$O$_6$},
author = {W. Tian and C. Svoboda and M. Ochi and M. Matsuda and H. B. Cao and J. -G. Cheng and B. C. Sales and D. G. Mandrus and R. Arita and N. Trivedi and J. -Q. Yan},
journal= {arXiv preprint arXiv:1504.03642},
year = {2019}
}