Two-triplon excitations of the Kitaev-Heisenberg-Bilayer

Abstract

We study the spectrum of a bilayer of Kitaev magnets on the honeycomb lattice, coupled by Heisenberg exchange in the quantum-dimer phase at strong interlayer coupling. Using the perturbative Continuous Unitary transformation (pCUT) we perform series expansion starting from the fully dimerized limit, to evaluate the elementary excitations, reaching up to and focusing on the two-triplon sector. In stark contrast to conventional bilayer quantum magnets, and because of the broken $SU(2)$-invariance, encoded in the intralayer directional compass-exchange, the bilayer Kitaev magnet is shown to exhibit a rich structure of two-triplon scattering-state continua, as well as several collective two-triplon (anti)bound states. Direct physical pictures for the occurrence of the latter are provided and the (anti)bound states are studied versus the stacking type, the spin components, and the exchange parameters. In addition to the two-triplon spectra, we investigate a corresponding experimental probe by evaluating the magnetic Raman-scattering intensity. We find a very strong sensitivity of this intensity on the two-triplon interactions and the scattering geometry, however a signal from the (anti)bound states appears only in very close proximity to the continuum.

arXiv comment13 pages, 11 figures

References in corpus (49)

• 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
• Controlling Spin Exchange Interactions of Ultracold Atoms in Optical Lattices
• Kitaev-Heisenberg Model on Honeycomb Lattice: Possible Exotic Phases in Iridium Oxides $A_2$IrO${}_3$
• Proximate Kitaev Quantum Spin Liquid Behaviour in α-RuCl${}_3$
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Neutron tomography of magnetic Majorana fermions in a proximate quantum spin liquid
• Models and Materials for Generalized Kitaev Magnetism
• Quantum magnetism and criticality
• Exact dimer ground state of the two dimensional Heisenberg spin system SrCu_2(BO_3)_2
• Topological characterization of quantum phase transitions in a S=1/2 spin model
• Excitations in the field-induced quantum spin liquid state of alpha-RuCl3
• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• Excitonic Magnetism in Van Vleck-type d^4 Mott Insulators
• Dimensional reduction at a quantum critical point
• Perturbation Theory by Flow Equations: Dimerized and Frustrated S=1/2 Chain
• Field- and pressure-induced magnetic quantum phase transitions in TlCuCl_3
• Li${}_2$VO(Si,Ge)O${}_4$, a prototype of a two-dimensional frustrated quantum Heisenberg antiferromagnet
• Exact results on the Kitaev model on a hexagonal lattice: spin states, string and brane correlators, and anyonic excitations
• High-precision finite-size scaling analysis of the quantum-critical point of S=1/2 Heisenberg antiferromagnetic bilayers
• Hall effect of triplons in a dimerized quantum magnet
• Dispersion and Symmetry of Bound States in the Shastry-Sutherland Model
• Quantum and classical criticality in a dimerized quantum antiferromagnet
• New Type Phase Transition of Li2RuO3 with Honeycomb Structure
• Direct observation of the multiple spin gap excitations in two-dimensional dimer system SrCu2(BO3)2
• Magnon bound states vs. anyonic Majorana excitations in the Kitaev honeycomb magnet $\alpha$-RuCl${}_3$
• Topological Triplon Modes and Bound States in a Shastry-Sutherland Magnet
• Collective Singlet Excitations and Evolution of Raman Spectral Weights in the 2D Spin Dimer Compound SrCu2(BO3)2
• Bond Algebras and Exact Solvability of Hamiltonians: Spin S=1/2 Multilayer Systems and Other Curiosities
• Magnetism of a tetrahedral cluster spin-chain
• Quantum Statistics of Interacting Dimer Spin Systems
• Quasiparticle-continuum level repulsion in a quantum magnet
• High Order Perturbation Theory for Spectral Densities of Multi-Particle Excitations: S=1/2 Two-Leg Heisenberg Ladder
• Dynamic Structure Factor of the Two-Dimensional Shastry-Sutherland Model
• Singlet-triplet dispersion reveals additional frustration in the triangular dimer compound Ba${}_3$Mn${}_2$O${}_8$
• Raman scattering in a Heisenberg {\boldmath $S=1/2$} antiferromagnet on the triangular lattice
• Interlayer Coupling Effect on a Bilayer Kitaev Model
• Bilayer Kitaev models: Phase diagrams and novel phases
• Non-linear bond-operator theory and 1/d expansion for coupled-dimer magnets I: Paramagnetic phase
• Nontrivial Triplon Topology and Triplon Liquid in Kitaev-Heisenberg-type Excitonic Magnets
• Frustrated spin-$\frac{1}{2}$ Heisenberg magnet on a square-lattice bilayer: High-order study of the quantum critical behavior of the $J_1$--$J_2$--$J_1^{\perp }$ model
• Highly frustrated magnetism in relativistic ${\mathbf{d}}^4$ Mott insulators: Bosonic analog of Kitaev honeycomb model
• RVB gauge theory and the Topological degeneracy in the Honeycomb Kitaev model
• Non-linear bond-operator theory and 1/d expansion for coupled-dimer magnets II: Antiferromagnetic phase and quantum phase transition
• Low temperature properties in the Bilayer Kitaev model
• Two-particle bound states and one-particle structure factor in a Heisenberg bilayer system
• Quantum phase transitions in the Triangular-lattice Bilayer Heisenberg Model
• Raman cross section of spin ladders
• Ground-state properties for bilayer Kitaev model: dimer expansion study

Cited by in corpus (2)

• Series expansions in closed and open quantum many-body systems with multiple quasiparticle types
• Emergent Hyper-Magic Manifold in Twisted Kitaev Bilayers