Possible proximity of the Mott insulating iridate Na 2 IrO 3 to a topological phase: Phase diagram of the Heisenberg-Kitaev model in a magnetic field
Hong‐Chen Jiang, Zheng‐Cheng Gu, Xiao-Liang Qi +1 more
Motivated by the recent experimental observation of a Mott insulating state for the layered iridate Na${}_{2}$IrO${}_{3}$, we discuss possible ordering states of the effective iridium moments in the presence of strong spin-orbit coupling and a magnetic field. For a field pointing in the $\ensuremath{\langle}111\ensuremath{\rangle}$ direction---perpendicular to the hexagonal lattice formed by the iridium moments---we find that a combination of Heisenberg and Kitaev exchange interactions gives rise to a rich phase diagram with both symmetry breaking magnetically ordered phases as well as a topologically ordered phase that is stable over a small range of coupling parameters. Our numerical simulations further indicate two exotic critical points at the boundaries between these ordered phases.
arXiv:1101.1145•Physical Review B•Jun 6, 2011•216 citations