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Incommensurate counterrotating magnetic order stabilized by Kitaev interactions in the layered honeycomb alpha-Li2IrO3

TitleIncommensurate counterrotating magnetic order stabilized by Kitaev interactions in the layered honeycomb alpha-Li2IrO3
Publication TypeJournal Article
Year of Publication2016
AuthorsWilliams, SC, Johnson, RD, Freund, F, Choi, S, Jesche, A, Kimchi, I, Manni, S, Bombardi, A, Manuel, P, Gegenwart, P, Coldea, R
JournalPhysical Review B
Volume93
Pagination195158
Date Published05
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000376637700001
Keywordsiridate, li2iro3, physics
Abstract

The layered honeycomb magnet alpha-Li2IrO3 has been theoretically proposed as a candidate to display unconventional magnetic behaviour associated with Kitaev interactions between spin-orbit entangled j(eff) = 1/2 magnetic moments on a honeycomb lattice. Here we report single crystal magnetic resonant x-ray diffraction combined with powder magnetic neutron diffraction to reveal an incommensurate magnetic order in the honeycomb layers with Ir magnetic moments counterrotating on nearest-neighbor sites. This unexpected type of magnetic structure for a honeycomb magnet cannot be explained by a spin Hamiltonian with dominant isotropic (Heisenberg) couplings. The magnetic structure shares many key features with the magnetic order in the structural polytypes beta- and gamma-Li2IrO3, understood theoretically to be stabilized by dominant Kitaev interactions between Ir moments located on the vertices of three-dimensional hyperhoneycomb and stripyhoneycomb lattices, respectively. Based on this analogy and a theoretical soft-spin analysis of magnetic ground states for candidate spin Hamiltonians, we propose that Kitaev interactions also dominate in alpha-Li2IrO3, indicative of universal Kitaev physics across all three members of the harmonic honeycomb family of Li2IrO3 polytypes.

DOI10.1103/PhysRevB.93.195158
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Alternate JournalPhys. Rev. B