Easy-plane anisotropic-exchange magnets on a honeycomb lattice: quantum effects and dealing with them

Abstract

We provide analytical and numerical insights into the phase diagram and other properties of the extended Kitaev-Heisenberg model on the honeycomb lattice in the {\it easy-plane} limit, in which interactions are only between spin components that belong to the plane of magnetic ions. This parameter subspace allows for a much-needed systematic {\it quantitative} investigation of spin excitations in the ordered phases and of their generic features. Specifically, we demonstrate that in this limit one can consistently take into account magnon interactions in both zero-field zigzag and field-polarized phases. For the nominally polarized phase, we propose a regularization of the unphysical divergences that occur at the critical field and are plaguing the $1/S$-approximation in this class of models. For the explored parameter subspace, all symmetry-allowed terms of the standard parametrization of the extended Kitaev-Heisenberg model, such as $K$, $J$, and $\Gamma$, are significant, making the offered consideration relevant to a much wider parameter space. The dynamical structure factor near paramagnetic critical point illustrates this relevance by showing features that are reminiscent of the ones observed in $\alpha$-RuCl${}_3$, underscoring that they are not unique and should be common to a wide range of parameters of the model and, by an extension, to other materials.

28 pages, 14 figures

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Cited by in corpus (16)

• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Quantum Spin Dynamics Due to Strong Kitaev Interactions in the Triangular-Lattice Antiferromagnet CsCeSe${}_2$
• Proximate Dirac spin liquid in honeycomb lattice $J_1$-$J_3$ XXZ model: Numerical study and application to cobaltates
• Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model
• Magnon interactions in the quantum paramagnetic phase of CoNb${}_2$O${}_6$
• The Saga of $\alpha$-RuCl${}_3$: Parameters, Models, and Phase Diagrams
• Thermal Hall effect incorporating magnon damping in localized spin systems
• Topological phase diagrams of in-plane field polarized Kitaev magnets
• Cobalt-Based Pyroxenes: A New Playground for Kitaev Physics and Ising Model Realization
• High Chern numbers and topological flat bands in high-field polarized Kitaev magnets on the star lattice
• Modified large-$N$ approach to gapless spin liquids, magnetic orders, and dynamics: Application to triangular lattice antiferromagnets
• Interaction-induced nonlinear magnon transport in noncentrosymmetric magnets
• Quantum selection of order and dynamic properties of Kitaev-Heisenberg ferromagnet on a triangular lattice
• Formulation of spin Nernst effect for spin-nonconserving insulating magnets
• Demystifying quantum escapism on the honeycomb lattice
• Self-consistent renormalized spin-wave theory of magnetic and topological transitions in two-dimensional honeycomb ferromagnets