Dominant Kitaev interactions in the honeycomb materials Na3Co2SbO6 and Na2Co2TeO6
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Date
2022-07-01
Journal Title
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Publisher
American Physical Society (APS)
Abstract
Cobaltates with 3d based layered honeycomb structure were recently proposed as Kitaev magnets and putative candidates to host the long-sought Kitaev spin liquid. Here we present inelastic neutron scattering results down to 50 mK for powder samples of Na3Co2SbO6 and Na2Co2TeO6, with high resolution in regions of low momentum and energy transfers. We compare the experimental data below the antiferromagnetic zigzag ordering temperature with dynamical structure factors obtained within spin wave theory. We search the wide parameter range of a K-J1-Γ-Γ′-J3 spin 1/2 model and identify the best fits to constant momentum cuts of the inelastic neutron data. The powder average limits our ability to uniquely select a best-fit model, but we find that the experimental data is matched equally well by two classes of parameters: one with a dominant K<0, |K/J1|∼5...25, and another with K>0, |K/J1|∼1. We show that these classes are equivalent under the exact self-duality transformation identified by Chaloupka and Khalliulin [Phys. Rev. B 92, 024413 (2015)10.1103/PhysRevB.92.024413]. This model symmetry unifies a number of previous parameter estimates. Though the two cases are indistinguishable by our experiment, there is evidence in favor of the K<0 case. A purely isotropic Heisenberg model is incompatible with our results. ©2024 American Physical Society. All rights reserved.
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Keywords
Honeycomb structures, Materials, Magnets, Neutrons, Heisenberg model, Tellurium, Antimony, Cobalt
Citation
Sanders, A. L., Mole, R. A., Liu, J., Brown, A. J., Yu, D., Ling, C. D., & Rachel, S. (2022). Dominant Kitaev interactions in the honeycomb materials Na3 Co2 SbO6 and Na2 Co2 TeO6. Physical Review B, 106(1), 014413. doi: 10.1103/PhysRevB.106.014413