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Direct evidence for dominant bond-directional interactions in a honeycomb lattice iridate Na2IrO3

Název česky Přímý důkaz dominantních vazebně-směrových interakcí v iridátu Na2IrO3 s voštinovou mřížkou
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CHUN Sae Hwan KIM Jong-Woo KIM Jungho ZHENG H. STOUMPOS Constantinos C MALLIAKAS C.D. MITCHELL J.F. MEHLAWAT Kavita SINGH Yogesh CHOI Y. GOG T. AL-ZEIN A. SALA M. Moretti KRISCH M. CHALOUPKA Jiří JACKELI George KHALIULLIN Giniyat KIM B.J.

Druh Článek v odborném periodiku
Časopis / Zdroj Nature Physics
Fakulta / Pracoviště MU

Středoevropský technologický institut

Citace
WWW http://www.nature.com/nphys/journal/v11/n6/full/nphys3322.html
Doi http://dx.doi.org/10.1038/NPHYS3322
Obor Fyzika pevných látek a magnetismus
Klíčová slova spin interactions; frustrated magnetism; iridates; spin models
Popis Heisenberg interactions are ubiquitous in magnetic materials and play a central role in modelling and designing quantum magnets. Bond-directional interactions offer a novel alternative to Heisenberg exchange and provide the building blocks of the Kitaev model, which has a quantum spin liquid as its exact ground state. Honeycomb iridates, A2IrO3 (A = Na, Li), offer potential realizations of the Kitaev magnetic exchange coupling, and their reported magnetic behaviour may be interpreted within the Kitaev framework. However, the extent of their relevance to the Kitaev model remains unclear, as evidence for bond-directional interactions has so far been indirect. Herewe present direct evidence for dominant bond-directional interactions in antiferromagnetic Na2IrO3 and show that they lead to strong magnetic frustration. Diffuse magnetic X-ray scattering reveals broken spin-rotational symmetry even above the Neel temperature, with the three spin components exhibiting short-range correlations along distinct crystallographic directions. This spin- and real-space entanglement directly uncovers the bond-directional nature of these interactions, thus providing a direct connection between honeycomb iridates and Kitaev physics.
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