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Durham University

Department of Physics

Staff profile

Publication details for Professor Tom Lancaster

Choi, S.K., Coldea, R., Kolmogorov, A.N., Lancaster, T., Mazin, I.I., Blundell, S.J., Radaelli, P.G., Singh, Yogesh, Gegenwart, P., Choi, K.R., Cheong, S.-W., Baker, P.J., Stock, C. & Taylor, J. (2012). Spin Waves and Revised Crystal Structure of Honeycomb Iridate Na2IrO3. Physical Review Letters 108(12): 127204.

Author(s) from Durham

Abstract

We report inelastic neutron scattering measurements on Na2IrO3, a candidate for the Kitaev spin model
on the honeycomb lattice. We observe spin-wave excitations below 5 meV with a dispersion that can be
accounted for by including substantial further-neighbor exchanges that stabilize zigzag magnetic order.
The onset of long-range magnetic order below TN ¼ 15:3 K is confirmed via the observation of oscillations in zero-field muon-spin rotation experiments. Combining single-crystal diffraction and
density functional calculations we propose a revised crystal structure model with significant departures
from the ideal 90 Ir-O-Ir bonds required for dominant Kitaev exchange.