Spin waves and revised crystal structure of honeycomb iridate Na2IrO3.

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...

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Dades bibliogràfiques
Autors principals: Choi, S, Coldea, R, Kolmogorov, A, Lancaster, T, Mazin, I, Blundell, S, Radaelli, P, Singh, Y, Gegenwart, P, Choi, K, Cheong, S, Baker, P, Stock, C, Taylor, J
Format: Journal article
Idioma:English
Publicat: 2012
Descripció
Sumari: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 T(N)=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.