• DOI:10.1103/PhysRevB.92.165108
• Corpus ID: 118308442

Magnetic orders proximal to the Kitaev limit in frustrated triangular systems: Application to Ba 3 IrTi 2 O 9

@article{Catuneanu2015MagneticOP,
  title={Magnetic orders proximal to the Kitaev limit in frustrated triangular systems: Application to Ba 3 IrTi 2 O 9},
  author={Andrei Catuneanu and Jeffrey G. Rau and Heung-Sik Kim and Hae Young Kee},
  journal={Physical Review B},
  year={2015},
  volume={92},
  pages={165108}
}

• A. Catuneanu, J. Rau, +1 author H. Kee
• Published 22 July 2015
• Materials Science
• Physical Review B

Frustrated transition-metal compounds in which spin-orbit coupling (SOC) and electron correlation work together have attracted much attention recently. In the case of $5d$ transition metals, where SOC is large, ${j}_{\text{eff}}=1/2$ bands near the Fermi level are thought to encompass the essential physics of the material, potentially leading to a concrete realization of exotic magnetic phases such as the Kitaev spin liquid. Here, we derive a spin model on a triangular lattice based on ${j}_{\text{eff}}=1/2$ pseudospins that interact via antiferromagnetic Heisenberg ($J$) and Kitaev ($K$) exchanges, and crucially, an anisotropic $(\mathrm{\ensuremath{\Gamma}})$ exchange. Our classical analysis of the spin model reveals that, in addition to small regions of ${120}^{\ensuremath{\circ}}, {\mathbb{Z}}_{2}$/dual-${\mathbb{Z}}_{2}$ vortex crystal and nematic phases, the stripy and ferromagnetic phases dominate the $J\ensuremath{-}K\ensuremath{-}\mathrm{\ensuremath{\Gamma}}$ phase diagram. We apply our model to the $5d$ transition-metal compound, ${\mathrm{Ba}}_{3}{\mathrm{IrTi}}_{2}{\mathrm{O}}_{9}$, in which the ${\mathrm{Ir}}^{4+}$ ions form layered two-dimensional triangular lattices. We compute the band structure and nearest-neighbor hopping parameters using ab initio calculations. By combining our ab initio and classical analyses, we predict that ${\mathrm{Ba}}_{3}{\mathrm{IrTi}}_{2}{\mathrm{O}}_{9}$ has a stripy ordered magnetic ground state.