Disorder effects in the Kitaev-Heisenberg model

Abstract

We study the interplay of disorder and Heisenberg interactions in Kitaev model on honeycomb lattice. The effect of disorder on the transition between Kitaev spin liquid and magnetic ordered states as well as the stability of magnetic ordering is investigated. Using Lanczos exact diagonalization we discuss the consequences of two types of disorder: (i) random-coupling disorder and (ii) singular-coupling disorder. They exhibit qualitatively similar effects in the pure Kitaev-Heisenberg model without long-range interactions. The range of spin liquid phases is reduced and the transition to magnetic ordered phases becomes more crossover-like. Furthermore, the long-range zigzag and stripy orderings in the clean system are replaced by their three domains with different ordering direction. Especially in the crossover range the coexistence of magnetically ordered and Kitaev spin-liquid domains is possible. With increasing the disorder strength the area of domains becomes smaller and the system goes into a spin-glass state. However, the disorder effect is different in magnetically ordered phases caused by long-range interactions. The stability of such magnetic ordering is diminished by singular-coupling disorder, and accordingly, the range of spin-liquid regime is extended. This mechanism may be relevant to materials like $\alpha$-RuCl${}_3$ and H${}_3$LiIr${}_2$O${}_6$ where the zigzag ground state is stabilized by weak long-range interactions. We also find that the flux gap closes at a critical disorder strength and vortices appears in the flux arrangement. Interestingly, the vortices tend to form kinds of commensurate ordering.

Phys. Rev. Research 5, 023009 (2023)

References in corpus (11)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Models and Materials for Generalized Kitaev Magnetism
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Disorder in a quantum spin liquid: flux binding and local moment formation
• Physical states and finite-size effects in Kitaev's honeycomb model: Bond disorder, spin excitations, and NMR lineshape
• Thermodynamic and Transport Properties in Disordered Kitaev Models
• Effect of structural disorder on the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$
• Susceptibility anisotropy and its disorder evolution in models for Kitaev materials
• Spin- and Flux-gap Renormalization in the Random Kitaev Spin Ladder
• Gapless excitations in non-Abelian Kitaev spin liquids with line defects

Cited by in corpus (7)

• Kitaev Quantum Spin Liquids
• A Kitaev-type spin liquid on a quasicrystal
• Momentum-independent magnetic excitation continuum in the honeycomb iridate H${}_3$LiIr${}_2$O${}_6$
• Defect-Induced Low-Energy Majorana Excitations in the Kitaev Magnet $\alpha$-RuCl${}_3$
• Spin dynamics in the Dirac $U(1)$ spin liquid YbZn${}_2$GaO${}_5$
• Vacancies in generic Kitaev spin liquids
• Bond disorder in extended Heisenberg-Kitaev models: Spin textures and in-gap states in the high-field regime