Field-induced decays in $XXZ$ triangular-lattice antiferromagnets

Abstract

We investigate field-induced transformations in the dynamical response of the $XXZ$ model on the triangular lattice that are associated with the anharmonic magnon coupling and decay phenomena. A set of concrete theoretical predictions is made for a close physical realization of the spin-1/2 $XXZ$ model, Ba${}_3$CoSb${}_2$O${}_9$. We demonstrate that dramatic modifications in magnon spectrum must occur in low out-of-plane fields that are easily achievable for this material. The hallmark of the effect is a coexistence of the clearly distinct well-defined magnon excitations with significantly broadened ones in different regions of the $\mathbf{k}-\omega$ space. The field-induced decays are generic for this class of models and become more prominent at larger anisotropies and in higher fields.

5 p. + 4 figs main, 6+ p. + 8 figs Supp, typos corrected, Sqw replotted, few changes

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Cited by in corpus (3)

• Avoided quasiparticle decay and enhanced excitation continuum in the spin-1/2 near-Heisenberg triangular antiferromagnet Ba3CoSb2O9
• Magnon damping in the zigzag phase of the Kitaev-Heisenberg-$\Gamma$ model on a honeycomb lattice
• Topological Magnon Bands and Unconventional Thermal Hall Effect on the Frustrated Honeycomb and Bilayer Triangular Lattice