• DOI:10.1103/physrevb.102.155134
• Corpus ID: 220404341

Heisenberg-Kitaev model in a magnetic field: 1/S expansion

@article{Cnsoli2020HeisenbergKitaevMI,
  title={Heisenberg-Kitaev model in a magnetic field: 
1/S
 expansion},
  author={Pedro M. C{\^o}nsoli and Lukas Janssen and Matthias Vojta and Eric C. Andrade},
  journal={Physical Review B},
  year={2020},
  volume={102},
  pages={155134}
}

• P. Cônsoli, L. Janssen, +1 author E. Andrade
• Published 7 July 2020
• Physics, Materials Science
• Physical Review B

The exact solution of Kitaev's spin-$1/2$ honeycomb spin-liquid model has sparked an intense search for Mott insulators hosting bond-dependent Kitaev interactions, of which ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$ and $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Ru}{\mathrm{Cl}}_{3}$ are prime examples. Subsequently, it has been proposed that also spin-1 and spin-$3/2$ analogs of Kitaev interactions may occur in materials with strong spin-orbit coupling. As a minimal model to describe these Kitaev materials, we study the Heisenberg-Kitaev Hamiltonian in a consistent $1/S$ expansion, with $S$ being the spin size. We present a comprehensive study of this model in the presence of an external magnetic field applied along two different directions, [001] and [111], for which an intricate classical phase diagram has been reported. In both settings, we employ spin-wave theory in a number of ordered phases to compute phase boundaries at the next-to-leading order in $1/S$ and show that quantum corrections substantially modify the classical phase diagram. More broadly, our work presents a consistent route to investigate the leading quantum corrections in spin models that break spin-rotational symmetry.