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arXiv · 1806.04247

Anisotropic antiferromagnetic order in spin-orbit coupled trigonal lattice Ca2Sr2IrO6

Jieming Sheng·Feng Ye·Christina Hoffmann·Valentino R. Cooper·Satoshi Okamoto·Jasminka Terzic·Hao Zheng·Hengdi Zhao·G. Cao
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Abstract

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 $R\bar3$ with two distinct Ir sites. The system exhibits long-range antiferromagnetic order below $T_N = 13.1$ 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$^\circ$ towards the $c$ axis. The ordered moment is 0.66(3) $μ_B$/Ir, larger than other iridates where iridium ions form corner- or edge-sharing $\rm IrO_6$ octahedral networks. The tilting angle is reduced to $\approx19^\circ$ 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 $\sim0.5$~eV.

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Jieming Sheng, Feng Ye, Christina Hoffmann, Valentino R. Cooper, Satoshi Okamoto, Jasminka Terzic, Hao Zheng, Hengdi Zhao, G. Cao. 2018-06-11. Anisotropic antiferromagnetic order in spin-orbit coupled trigonal lattice Ca2Sr2IrO6. https://doi.org/10.1103/physrevb.97.235116

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