A Kondo route to spin inhomogeneities in the honeycomb Kitaev model

Abstract

Paramagnetic impurities in a quantum spin-liquid can result in Kondo effects with highly unusual properties. We have studied the effect of locally exchange-coupling a paramagnetic impurity with the spin-1/2 honeycomb Kitaev model in its gapless spin-liquid phase. The (impurity) scaling equations are found to be insensitive to the sign of the coupling. The weak and strong coupling fixed points are stable, with the latter corresponding to a noninteracting vacancy and an interacting, spin-1 defect for the antiferromagnetic and ferromagnetic cases respectively. The ground state in the strong coupling limit in both cases has a nontrivial topology associated with a finite Z2 flux at the impurity site. For the antiferromagnetic case, this result can be obtained straightforwardly owing to the integrability of the Kitaev model with a vacancy. The strong-coupling limit of the ferromagnetic case is however nonintegrable, and we address this problem through exact-diagonalization calculations with finite Kitaev fragments. Our exact diagonalization calculations indicate that that the weak to strong coupling transition and the topological phase transition occur rather close to each other and are possibly coincident. We also find an intriguing similarity between the magnetic response of the defect and the impurity susceptibility in the two-channel Kondo problem.

9 pages, 4 figures, revtex4-1

References in corpus (8)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Proximate Kitaev Quantum Spin Liquid Behaviour in α-RuCl${}_3$
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Exact results for spin dynamics and fractionization in the Kitaev Model
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• Magnetic droplets in a metal close to a ferromagnetic quantum critical point
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Cited by in corpus (14)

• Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet $\alpha$-RuCl${}_3$
• Spin liquid mediated RKKY interaction
• $Z_2$ flux binding to higher-spin impurities in the Kitaev spin liquid
• Competition between Kondo and Kitaev Physics in Kitaev clusters coupled to a fermionic bath
• Dilution of the magnetic lattice in the Kitaev candidate $\alpha$-RuCl${}_3$ by Rh${}^{3+}$ doping
• Magnetic order through Kondo coupling to quantum spin liquids
• Vacancies in generic Kitaev spin liquids
• Field tuning Kitaev systems for spin fractionalization and topological order
• Robustness of Vacancy-Bound Non-Abelian Anyons in the Kitaev Model in a Magnetic Field
• Microscopic theory of field-tuned topological transitions in the Kitaev honeycomb model
• Kondo Screening Cloud Scaling: Impurity Entanglement and Magnetization
• Detecting symmetry fractionalization in gapped quantum spin liquids by magnetic impurities
• Chiral $p-$wave superconductivity in Pb${}_{1-x}$Sn${}_x$Te: signatures from bound-state spectra and wavefunctions
• Realizing Majorana fermion modes in the Kitaev model