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Kitaev interactions between j = 1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: insights from ab initio quantum chemistry calculations

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posted on 08.08.2018, 15:48 authored by Vamshi M. Katukuri, Satoshi Nishimoto, Viktor Yushankhai, A. Stoyanova, H. Kandpal, Sungkyun Choi, R. Coldea, Ioannis RousochatzakisIoannis Rousochatzakis, Liviu Hozoi, Jeroen van den Brink
Na2IrO3, a honeycomb 5d5oxide, has been recently identified as a potential realization of the Kitaev spin lattice. The basic feature of this spin model is that for each of the three metal-metal links emerging out of a metal site, the Kitaev interaction connects only spin components perpendicular to the plaquette defined by the magnetic ions and two bridging ligands. The fact that reciprocally orthogonal spin components are coupled along the three different links leads to strong frustration effects and nontrivial physics. While the experiments indicate zigzag antiferromagnetic order in Na2IrO3, the signs and relative strengths of the Kitaev and Heisenberg interactions are still under debate. Herein we report results of ab initio many-body electronic-structure calculations and establish that the nearest-neighbor exchange is strongly anisotropic with a dominant ferromagnetic Kitaev part, whereas the Heisenberg contribution is significantly weaker and antiferromagnetic. The calculations further reveal a strong sensitivity to tiny structural details such as the bond angles. In addition to the large spin-orbit interactions, this strong dependence on distortions of the Ir2O2 plaquettes singles out the honeycomb 5d5oxides as a new playground for the realization of unconventional magnetic ground states and excitations in extended systems.

Funding

L.H. acknowledges financial support from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).

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  • Science

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  • Physics

Published in

New Journal of Physics

Volume

16

Citation

KATUKURI, V.M. ... et al, 2014. Kitaev interactions between j = 1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: insights from ab initio quantum chemistry calculations. New Journal of Physics, 16 (2014), 013056.

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IOP Publishing © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

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This work is made available according to the conditions of the Creative Commons Attribution 3.0 Unported (CC BY 3.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by/3.0/

Publication date

2014

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Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

ISSN

1367-2630

Language

en

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