Raman Signatures of Strong Kitaev Exchange Correlations in (Na${}_{1-x}$Li${}_x$)${}_2$IrO${}_3$ : Experiments and Theory

Abstract

Inelastic light scattering studies on single crystals of (Na${}_{1-x}$Li${}_x$)${}_2$IrO${}_3$ ($x=0,0.05$ and $0.15$) show a polarization independent broad band at $\sim$~2750 cm${}^{-1}$ with a large band-width $\sim 1800$~cm${}^{-1}$. For Na${}_2$IrO${}_3$ the broad band is seen for temperatures $\le 200$~K and persists inside the magnetically ordered state. For Li doped samples, the intensity of this mode increases, shifts to lower wave-numbers and persists to higher temperatures. Such a mode has recently been predicted (Knolle et.al.) as a signature of the Kitaev spin liquid. We assign the observation of the broad band to be a signature of strong Kitaev-exchange correlations. The fact that the broad band persists even inside the magnetically ordered state suggests that dynamically fluctuating moments survive even below $T_N$. This is further supported by our mean field calculations. The Raman response calculated in mean field theory shows that the broad band predicted for the spin liquid state survives in the magnetically ordered state near the zigzag-spin liquid phase boundary. A comparison with the theoretical model gives an estimate of the Kitaev exchange interaction parameter to be $J_K\approx 57$~meV.

14pages 4 figures

References in corpus (12)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Scattering Continuum and Possible Fractionalized Excitations in $\alpha$-RuCl${}_3$
• Crystal field splitting and correlation effect on the electronic structure of A2IrO3
• Kitaev interactions between j=1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: insights from ab initio quantum chemistry calculations
• Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap
• Raman Scattering Signatures of Kitaev Spin Liquids in A${}_2$ IrO${}_3$ Iridates
• Importance of anisotropic exchange interactions in honeycomb iridates. Minimal model for zigzag antiferromagnetic order in Na${}_2$IrO${}_3$
• Effect of nonmagnetic dilution in honeycomb lattice iridates Na${}_2$IrO${}_3$ and Li${}_2$IrO${}_3$
• Confinement-Deconfinement Transition as an Indication of Spin-Liquid-Type Behavior in Na${}_2$IrO${}_3$
• Effect of isoelectronic doping on honeycomb lattice iridate A_2IrO_3
• How to detect weak emergent broken-symmetries of the Kagome antiferromagnet from Raman spectroscopy

Cited by in corpus (21)

• Models and Materials for Generalized Kitaev Magnetism
• Dominant Kitaev interactions in the honeycomb materials Na${}_3$Co${}_2$SbO${}_6$ and Na${}_2$Co${}_2$TeO${}_6$
• Heat capacity evidence for proximity to the Kitaev QSL in A${}_2$IrO${}_3$ ($A=$ Na, Li)
• Field-induced intertwined orders in 3D Mott-Kitaev honeycomb $\beta$-Li2IrO3
• Thermodynamic and Transport Properties in Disordered Kitaev Models
• Destabilization of magnetic order in a dilute Kitaev spin liquid candidate
• Magnetic Raman continuum in single crystalline H${}_3$LiIr${}_2$O${}_6$
• Spin dynamics in the Kitaev model with disorder: Quantum Monte Carlo study of dynamical spin structure factor, magnetic susceptibility, and NMR relaxation rate
• Kitaev magnetism through the prism of lithium iridate
• Spin-phonon coupling in hole-doped pyrochlore iridates Y${}_2$(Ir${}_{1-x}$Ru${}_x$)${}_2$O${}_7$: A Raman scattering study
• Electronic and magnetic properties of iridium ilmenites $A$IrO${}_3$ ($A=$ Mg, Zn, and Mn)
• Fingerprints of quantum spin ice in Raman scattering
• Raman scattering in correlated thin films as a probe of chargeless surface states
• Field evolution of low-energy excitations in the hyperhoneycomb magnet $\beta$-Li${}_2$IrO${}_3$
• Spin liquid like Raman signatures in hyperkagome iridate Na${}_4$Ir${}_3$O${}_8$
• First-order magneto-structural transition in single crystals of the honeycomb lattice Ruthenate Li${}_2$RuO${}_3$
• Raman spectroscopy of the low dimensional antiferromagnet with large Neel temperature SrRu2O6
• Competition between magnetic order and charge localization in Na${}_2$IrO${}_3$ thin crystal devices
• The origin of exciton mass in a frustrated Mott insulator Na${}_2$IrO${}_3$
• Topological Majorana flat bands in the Kitaev model on a Bishamon-kikko lattice
• Magnetic-field induced melting of long-range magnetic order akin to Kitaev insulators in the metallic compound Tb5Si3