Momentum-dependent magnon lifetime in the metallic non-collinear triangular antiferromagnet CrB2

Abstract

Non-collinear magnetic order arises for various reasons in several magnetic systems and exhibits interesting spin dynamics. Despite its ubiquitous presence, little is known of how magnons, otherwise stable quasiparticles, decay in these systems, particularly in metallic magnets. Using inelastic neutron scattering, we examine the magnetic excitation spectra in a metallic non-collinear antiferromagnet CrB${}_2$, in which Cr atoms form a triangular lattice and display incommensurate magnetic order. Our data show intrinsic magnon damping and continuum-like excitations that cannot be explained by linear spin wave theory. The intrinsic magnon linewidth $\Gamma (q,E_q)$ shows very unusual momentum dependence, which our analysis shows to originate from the combination of two-magnon decay and the Stoner continuum. By comparing the theoretical predictions with the experiments, we identify where in the momentum and energy space one of the two factors becomes more dominant. Our work constitutes a rare comprehensive study of the spin dynamics in metallic non-collinear antiferromagnets. It reveals, for the first time, definite experimental evidence of the higher-order effects in metallic antiferromagnets.

arXiv comment6 pages, 4 figures, accepted for publication in PRL

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Cited by in corpus (7)

• Spin Dynamics in van der Waals Magnetic Systems
• Bond-dependent anisotropy and magnon decay in cobalt-based Kitaev triangular antiferromagnet
• Instabilities of heavy magnons in an anisotropic magnet
• Decay and renormalization of a longitudinal mode in a quasi-two-dimensional antiferromagnet
• Nonlinear Decay of Quantum Confined Magnons in Itinerant Ferromagnets
• Spin dynamics of triple-Q magnetic orderings in a triangular lattice: Implications for multi-Q orderings in general two-dimensional lattices
• Incommensurate magnetic ordering in CrB${}_2$