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de la Torre A, Zager B, Bahrami F, Upton MH, Kim J, Fabbris G, Lee GH, Yang W, Haskel D, Tafti F, Plumb KW. Momentum-independent magnetic excitation continuum in the honeycomb iridate H 3LiIr 2O 6. Nat Commun 2023; 14:5018. [PMID: 37596328 PMCID: PMC10439105 DOI: 10.1038/s41467-023-40769-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 08/07/2023] [Indexed: 08/20/2023] Open
Abstract
Understanding the interplay between the inherent disorder and the correlated fluctuating-spin ground state is a key element in the search for quantum spin liquids. H3LiIr2O6 is considered to be a spin liquid that is proximate to the Kitaev-limit quantum spin liquid. Its ground state shows no magnetic order or spin freezing as expected for the spin liquid state. However, hydrogen zero-point motion and stacking faults are known to be present. The resulting bond disorder has been invoked to explain the existence of unexpected low-energy spin excitations, although data interpretation remains challenging. Here, we use resonant X-ray spectroscopies to map the collective excitations in H3LiIr2O6 and characterize its magnetic state. In the low-temperature correlated state, we reveal a broad bandwidth of magnetic excitations. The central energy and the high-energy tail of the continuum are consistent with expectations for dominant ferromagnetic Kitaev interactions between dynamically fluctuating spins. Furthermore, the absence of a momentum dependence to these excitations are consistent with disorder-induced broken translational invariance. Our low-energy data and the energy and width of the crystal field excitations support an interpretation of H3LiIr2O6 as a disordered topological spin liquid in close proximity to bond-disordered versions of the Kitaev quantum spin liquid.
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Affiliation(s)
- A de la Torre
- Department of Physics, Brown University, Providence, RI, 02912, USA.
| | - B Zager
- Department of Physics, Brown University, Providence, RI, 02912, USA
| | - F Bahrami
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - J Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - G-H Lee
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720, USA
| | - W Yang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - F Tafti
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA
| | - K W Plumb
- Department of Physics, Brown University, Providence, RI, 02912, USA.
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Sanders MB, Krizan JW, Plumb KW, McQueen TM, Cava RJ. NaSrMn 2F 7, NaCaFe 2F 7, and NaSrFe 2F 7: novel single crystal pyrochlore antiferromagnets. J Phys Condens Matter 2017; 29:045801. [PMID: 27875333 DOI: 10.1088/1361-648x/29/4/045801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The crystal structures and magnetic properties of three previously unreported A2B2F7 pyrochlore materials, NaSrMn2F7, NaCaFe2F7, and NaSrFe2F7 are presented. In these compounds, either S = 2Fe2+ or S = 5/2Mn2+ is on the B site, while nonmagnetic Na and Ca (Na and Sr) are disordered on the A site. The materials, which were grown as crystals via the floating zone method, display high effective magnetic moments and large Curie-Weiss thetas. Despite these characteristics, no ordering transition is detected. However, freezing of the magnetic spins, characterized by peaks in the susceptibility or specific heat, is observed at very low temperatures. The empirical frustration index, f = -θ CW/T f, for the materials are 36 (NaSrMn2F7), 27 (NaSrFe2F7), and 19 (NaCaFe2F7). AC susceptibility, DC susceptibility, and heat capacity measurements are used to characterize the observed spin glass behavior. The results suggest that the compounds are frustrated pyrochlore antiferromagnets with weak bond disorder. The magnetic phenomena that these fluoride pyrochlores exhibit, in addition to their availability as relatively large single crystals, make them promising candidates for the study of geometric magnetic frustration.
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Affiliation(s)
- M B Sanders
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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