Signatures of fractionalization in the optical phonons of hyperhoneycomb Kitaev magnet $\beta$-Li${}_2$IrO${}_3$

Abstract

In this study, we propose that the signatures of spin fractionalization in quantum magnets can be identified through a detailed analysis of the temperature dependence of the asymmetric Fano lineshape of optical phonons overlapping with a continuum of spin excitations. We focus on the hyperhoneycomb magnet $\beta$-Li${}_2$IrO${}_3$, a promising candidate for being in proximity to a three-dimensional Kitaev quantum spin liquid. The Raman response in $\beta$-Li${}_2$IrO${}_3$ notably displays a distinctive asymmetric Fano lineshape in the 24 meV Raman-active optical phonon. This asymmetry arises from the interaction between the discrete phonon mode and the spin excitation continuum, which could be fractionalized if the material is indeed near a quantum spin-liquid phase. Our theoretical model considers the coupling of this optical phonon to Majorana fermions in the Kitaev model on the hyperhoneycomb lattice. Our findings reveal that the temperature-dependent Fano lineshape is consistent with the fractionalization of spins into Majorana fermions and $\mathbb{Z}{}_2$ fluxes.

arXiv comment17 pages, 9 figures

References in corpus (40)

• Anyons in an exactly solved model and beyond
• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Quantum Spin Liquids
• High-throughput electronic band structure calculations: challenges and tools
• Quantum Spin Liquids
• Kitaev quantum spin liquid - concept and materialization
• A Field Guide to Spin Liquids
• Scattering Continuum and Possible Fractionalized Excitations in $\alpha$-RuCl${}_3$
• Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections
• Hyper-honeycomb iridate $\beta$-Li2IrO3 as a platform for Kitaev magnetism
• A new spin-anisotropic harmonic honeycomb iridate
• Unconventional magnetic order on the hyperhoneycomb Kitaev lattice in $\beta$-Li2IrO3: full solution via magnetic resonant x-ray diffraction
• Classification of gapless Z2 spin liquids in three-dimensional Kitaev models
• Relation between Kitaev magnetism and structure in $\alpha$-RuCl${}_3$
• Magnon bound states vs. anyonic Majorana excitations in the Kitaev honeycomb magnet $\alpha$-RuCl${}_3$
• Raman spectroscopic signature of fractionalized excitations in the harmonic-honeycomb iridates $\beta$- and $\gamma$-Li${}_2$IrO${}_3$
• High-Field Quantum Disordered State in $\alpha$-RuCl3: Spin Flips, Bound States, and a Multi-Particle Continuum
• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Theory of Raman response in three-dimensional Kitaev spin liquids: application to $\beta -$ and $\gamma -$Li${}_2$IrO${}_3$ compounds
• Phonon dynamics in the Kitaev spin liquid
• Field-induced intertwined orders in 3D Mott-Kitaev honeycomb $\beta$-Li2IrO3
• Topological spinon semimetals and gapless boundary states in three dimensions
• Raman evidence for dimerization and Mott collapse in $\alpha$-RuCl${}_3$ under pressures
• Magnetic structure and excitation spectrum of the hyperhoneycomb Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Phonon renormalization in the Kitaev quantum spin liquid
• Thermodynamic classification of three-dimensional Kitaev spin liquids
• Magnetic field-induced evolution of intertwined orders in the Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Probing spinon nodal structures in three-dimensional Kitaev spin liquids
• Kitaev magnetism through the prism of lithium iridate
• Temperature evolution of the phonon dynamics in the Kitaev spin liquid
• Magnon-spinon dichotomy in the Kitaev hyperhoneycomb $\beta$-Li${}_2$IrO${}_3$
• Footprints of the Kitaev spin liquid in the Fano lineshapes of the Raman active optical phonons
• Reentrant incommensurate order and anomalous magnetic torque in the Kitaev magnet $\beta$-${\text{Li}}_2{\text{IrO}}_3$
• Magnetic Excitations and Interactions in the Kitaev Hyperhoneycomb Iridate $\beta$-Li${}_2$IrO${}_3$
• Hidden spin-orbital order in the Kitaev hyperhoneycomb $\beta$-Li${}_2$IrO${}_3$
• Unconventional magnetic field response of the hyperhoneycomb Kitaev magnet $\beta -{\text{Li}}_2{\text{IrO}}_3$
• Phonon Dynamics in the Generalized Kitaev Spin Liquid
• Signatures of non-Loudon-Fleury Raman scattering in the Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Phonon Dynamics in the Chiral Kitaev Spin Liquid
• Sound attenuation in the hyperhoneycomb Kitaev spin liquid