Abstract
We study the high-temperature magnetic order in a quasi-two-dimensional honeycomb compound by measuring magnetization and neutron powder diffraction with both polarized and unpolarized neutrons. crystallizes into the hexagonal lead antimonate (, space group ) structure with layers of edge-sharing octahedra separated by ions. is found to order at K with Ru moments coupled antiferromagnetically both in plane and out of plane. The magnetic moment is 1.30(2) /Ru at room temperature and is along the crystallographic axis in the G-type magnetic structure. We perform density functional calculations with constrained random-phase approximation (RPA) to obtain the electronic structure and effective intra- and interorbital interaction parameters. The projected density of states shows strong hybridization between Ru and O . By downfolding to the target bands we extract the effective magnetic Hamiltonian and perform Monte Carlo simulations to determine the transition temperature as a function of inter- and intraplane couplings. We find a weak interplane coupling, 3% of the strong intraplane coupling, permits three-dimensional magnetic order at the observed .
- Received 14 April 2015
DOI:https://doi.org/10.1103/PhysRevB.92.100404
©2015 American Physical Society