Spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet α−Li2IrO3
| Autor: | Choi, S, Manni, S, Singleton, J, Topping, CV, Lancaster, T, Blundell, SJ, Adroja, DT, Zapf, V, Gegenwart, P, Coldea, R |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Physical review B, 2019, Vol.99(5), pp.054426 [Peer Reviewed Journal] |
| Popis: | The layered honeycomb iridate $��$-Li$_2$IrO$_3$ displays an incommensurate magnetic structure with counterrotating moments on nearest-neighbor sites, proposed to be stabilized by strongly-frustrated anisotropic Kitaev interactions between spin-orbit entangled Ir$^{4+}$ magnetic moments. Here we report powder inelastic neutron scattering measurements that observe sharply dispersive low-energy magnetic excitations centered at the magnetic ordering wavevector, attributed to Goldstone excitations of the incommensurate order, as well as an additional intense mode above a gap $��\simeq2.3$ meV. Zero-field muon-spin relaxation measurements show clear oscillations in the muon polarization below the N��el temperature $T_{\rm N}\simeq15$ K with a time-dependent profile consistent with bulk incommensurate long-range magnetism. Pulsed field magnetization measurements observe that only about half the saturation magnetization value is reached at the maximum field of 64 T. A clear anomaly near 25 T indicates a transition to a phase with reduced susceptibility. The transition field has a Zeeman energy comparable to the zero-field gapped mode, suggesting gap suppression as a possible mechanism for the field-induced transition. 8 pages, 6 figures |
| Databáze: | OpenAIRE |
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