Direct evidence of a zigzag spin-chain structure in the honeycomb lattice: A neutron and x-ray diffraction investigation of single-crystal Na2IrO3

Feng Ye, Songxue Chi, Huibo Cao, Bryan C. Chakoumakos, Jaime A. Fernandez-Baca, Radu Custelcean, T. F. Qi, O. B. Korneta, G. Cao
2012 Physical Review B  
We have combined single crystal neutron and x-ray diffractions to investigate the magnetic and crystal structures of the honeycomb lattice Na_2IrO_3. The system orders magnetically below 18.1(2) K with Ir^4+ ions forming zigzag spin chains within the layered honeycomb network with ordered moment of 0.22(1) μ_B/Ir site. Such a configuration sharply contrasts the Néel or stripe states proposed in the Kitaev-Heisenberg model. The structure refinement reveals that the Ir atoms form nearly ideal 2D
more » ... oneycomb lattice while the IrO_6 octahedra experience a trigonal distortion that is critical to the ground state. The results of this study provide much-needed experimental insights into the magnetic and crystal structure crucial to the understanding of the exotic magnetic order and possible topological characteristics in the 5d-electron based honeycomb lattice.
doi:10.1103/physrevb.85.180403 fatcat:vyqowp7adjdyvouhnsyjrgj2xe