Abstract
Recently, realizations of Kitaev physics have been sought in the family of honeycomb iridates, originating from oxygen-mediated exchange through edge-shared octahedra. However, for the Mott insulator in these materials, exchange from direct -orbital overlap is relevant, and it was proposed that a Heisenberg term should be added to the Kitaev model. Here, we provide the generic nearest-neighbor spin Hamiltonian when both oxygen-mediated and direct overlap are present, containing a bond-dependent off-diagonal exchange in addition to Heisenberg and Kitaev terms. We analyze this complete model using a combination of classical techniques and exact diagonalization. Near the Kitaev limit, we find new magnetic phases, 120° and incommensurate spiral order, as well as extended regions of zigzag and stripy order. Possible applications to and are discussed.
- Received 5 November 2013
DOI:https://doi.org/10.1103/PhysRevLett.112.077204
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