Generic Spin Model for the Honeycomb Iridates beyond the Kitaev Limit

Jeffrey G. Rau, Eric Kin-Ho Lee, and Hae-Young Kee
Phys. Rev. Lett. 112, 077204 – Published 20 February 2014
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Abstract

Recently, realizations of Kitaev physics have been sought in the A2IrO3 family of honeycomb iridates, originating from oxygen-mediated exchange through edge-shared octahedra. However, for the jeff=1/2 Mott insulator in these materials, exchange from direct d-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 Na2IrO3 and Li2IrO3 are discussed.

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  • Received 5 November 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.077204

© 2014 American Physical Society

Authors & Affiliations

Jeffrey G. Rau1, Eric Kin-Ho Lee1, and Hae-Young Kee1,2,*

  • 1Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
  • 2Canadian Institute for Advanced Research/Quantum Materials Program, Toronto, Ontario MSG 1Z8, Canada

  • *Corresponding author. hykee@physics.utoronto.ca

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Issue

Vol. 112, Iss. 7 — 21 February 2014

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