We used single-crystal x-ray and neutron diffraction to investigate the crystal and magnetic structures of trigonal lattice iridate Ca2Sr2IrO6. The crystal structure is determined to be R3ˉ with two distinct Ir sites. The system exhibits long-range antiferromagnetic order below TN=13.1 K. The magnetic wave vector is identified as (0,0.5,1) with ferromagnetic coupling along the a axis and antiferromagnetic correlation along the b axis. Spins align dominantly within the basal plane along the [1,2,0] direction and tilt 34∘ towards the c axis. The ordered moment is 0.66(3) μB/Ir, larger than other iridates where iridium ions form corner- or edge-sharing IrO6 octahedral networks. The tilting angle is reduced to ≈19∘ when a magnetic field of 4.9 Tesla is applied along the c axis. Density functional theory calculations confirm that the experimentally determined magnetic configuration is the most probable ground state with an insulating gap ∼0.5~eV.
@article{arxiv.1806.04247,
title = {Anisotropic antiferromagnetic order in spin-orbit coupled trigonal lattice Ca2Sr2IrO6},
author = {Jieming Sheng and Feng Ye and Christina Hoffmann and Valentino R. Cooper and Satoshi Okamoto and Jasminka Terzic and Hao Zheng and Hengdi Zhao and G. Cao},
journal= {arXiv preprint arXiv:1806.04247},
year = {2018}
}