Footprints of the Kitaev spin liquid in the Fano lineshapes of the Raman active optical phonons

Abstract

We develop a theoretical description of the Raman spectroscopy in the spin-phonon coupled Kitaev system and show that it can provide intriguing observable signatures of fractionalized excitations characteristic of the underlying spin liquid phase. In particular, we obtain the explicit form of the phonon modes and construct the coupling Hamiltonians based on $D_{3d}$ symmetry. We then systematically compute the Raman intensity and show that the spin-phonon coupling renormalizes phonon propagators and generates the salient Fano linshape. We find that the temperature evolution of the Fano lineshape displays two crossovers, and the low temperature crossover shows pronounced magnetic field dependence. We thus identify the observable effect of the Majorana fermions and the $Z_2$ gauge fluxes encoded in the Fano lineshape. Our results explain several phonon Raman scattering experiments in the candidate material $\alpha$-RuCl${}_3$.

15 pages, 7 figures

References in corpus (14)

• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Inelastic Light Scattering From Correlated Electrons
• Models and Materials for Generalized Kitaev Magnetism
• Scattering Continuum and Possible Fractionalized Excitations in $\alpha$-RuCl${}_3$
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Raman Scattering Signatures of Kitaev Spin Liquids in A${}_2$ IrO${}_3$ Iridates
• The range of non-Kitaev terms and fractional particles in RuCl${}_3$
• Phonon dynamics in the Kitaev spin liquid
• Magnetoelastic coupling and effects of uniaxial strain in $\alpha$-RuCl${}_3$ from first principles
• Raman scattering in a Heisenberg {\boldmath $S=1/2$} antiferromagnet on the triangular lattice
• Temperature evolution of the phonon dynamics in the Kitaev spin liquid
• Further insights into the thermodynamics of the Kitaev honeycomb model
• Optical phonons coupled to a Kitaev spin liquid
• Non-Loudon-Fleury Raman scattering in spin-orbit coupled Mott insulators

Cited by in corpus (9)

• Thermal Hall Effect in the Kitaev-Heisenberg System with Spin-Phonon Coupling
• Phonon Dynamics in the Generalized Kitaev Spin Liquid
• Fluctuating Fractionalized Spins in Quasi Two-dimensional Magnetic V0.85PS3
• Signatures of non-Loudon-Fleury Raman scattering in the Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Polar phonons and magnetic excitations in the antiferromagnet CoF${}_2$
• Phonon Dynamics in the Chiral Kitaev Spin Liquid
• Sound attenuation in the hyperhoneycomb Kitaev spin liquid
• Signatures of fractionalization in the optical phonons of hyperhoneycomb Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Magnetostriction in the $J$-$K$-$\Gamma$ model: Application of the numerical linked cluster expansion