Spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet $\alpha$-Li${}_2$IrO${}_3$

Abstract

The layered honeycomb iridate $\alpha$-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 $\Delta \simeq 2.3$ meV. Zero-field muon-spin relaxation measurements show clear oscillations in the muon polarization below the Néel temperature $T_{\mathrm{N}}\simeq 15$ 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.

arXiv comment8 pages, 6 figures

References in corpus (40)

• Anyons in an exactly solved model and beyond
• Majorana quantization and half-integer thermal quantum Hall effect in a Kitaev spin liquid
• Proximate Kitaev Quantum Spin Liquid Behaviour in α-RuCl${}_3$
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Relevance of the Heisenberg-Kitaev model for the honeycomb lattice iridates A_2IrO_3
• Spin-Orbit Physics Giving Rise to Novel Phases in Correlated Systems: Iridates and Related Materials
• Neutron tomography of magnetic Majorana fermions in a proximate quantum spin liquid
• Spin waves and revised crystal structure of honeycomb iridate Na2IrO3
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Challenges in Design of Kitaev Materials: Magnetic Interactions from Competing Energy Scales
• The monoclinic crystal structure of $\alpha$-RuCl${}_3$ and the zigzag antiferromagnetic ground state
• Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections
• Spin-polarized muons in condensed matter physics
• Direct evidence of a zigzag spin chain structure in the honeycomb lattice: A neutron and x-ray diffraction investigation on single crystal $\mathrm{N}{\mathrm{a}}_2\mathrm{Ir}{\mathrm{O}}_3$
• Hyper-honeycomb iridate $\beta$-Li2IrO3 as a platform for Kitaev magnetism
• Dynamics of a two-dimensional quantum spin liquid: signatures of emergent Majorana fermions and fluxes
• Excitations in the field-induced quantum spin liquid state of alpha-RuCl3
• Long range magnetic ordering in Na${}_2$IrO${}_3$
• A new spin-anisotropic harmonic honeycomb iridate
• Phase Diagram of $\alpha$-RuCl${}_3$ in an in-plane Magnetic Field
• Incommensurate Counterrotating Magnetic Order Stabilized by Kitaev Interactions in the Layered Honeycomb $\alpha$-Li${}_2$IrO${}_3$
• Non-coplanar and counter-rotating incommensurate magnetic order stabilized by Kitaev interactions in $\gamma$-Li2IrO3
• Unconventional magnetic order on the hyperhoneycomb Kitaev lattice in $\beta$-Li2IrO3: full solution via magnetic resonant x-ray diffraction
• Probing $\alpha$-RuCl${}_3$ Beyond Magnetic Order: Effects of Temperature and Magnetic Field
• Magnetic excitation spectrum of Na2IrO3 probed with resonant inelastic x-ray scattering
• Theory of Magnetic Phase Diagrams in Hyperhoneycomb and Harmonic-honeycomb Iridates
• Unified theory of spiral magnetism in the harmonic-honeycomb iridates α, β, γ Li2IrO3
• Single crystal growth from separated educts and its application to lithium transition-metal oxides
• Breakdown of magnetic order in the pressurized Kitaev iridate $\beta$-Li${}_2$IrO${}_3$
• Field-induced intertwined orders in 3D Mott-Kitaev honeycomb $\beta$-Li2IrO3
• Pressure-tuning of bond-directional exchange interactions and magnetic frustration in hyperhoneycomb iridate $\beta$-$\mathrm{L}{\mathrm{i}}_2\mathrm{Ir}{\mathrm{O}}_3$
• Electron correlation in the two-dimensional triangle lattice of Na${}_x$CoO${}_2$
• Magnetic structure and excitation spectrum of the hyperhoneycomb Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Two iridates, two models, two approaches: a comparative study on magnetism in 3D honeycomb materials
• Resonant x-ray scattering reveals possible disappearance of magnetic order under hydrostatic pressure in the Kitaev candidate $\gamma$-Li${}_2$IrO${}_3$
• Magnetic field-induced evolution of intertwined orders in the Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Robust spin correlations at high magnetic fields in the honeycomb iridates
• Magnetic anisotropy of the alkali iridate Na${}_2$IrO${}_3$ at high magnetic fields: evidence for strong ferromagnetic Kitaev correlations
• Field-induced intermediate phase in $\alpha$-RuCl${}_3$: Non-coplanar order, phase diagram, and proximate spin liquid
• Spin dynamics of counterrotating Kitaev spirals via duality

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• Nesting instability of gapless U(1) spin liquids with spinon Fermi pockets in two dimensions