Momentum-Dependent Magnon Lifetime in the Metallic Noncollinear Triangular Antiferromagnet CrB2

Pyeongjae Park, Kisoo Park, Taehun Kim, Yusuke Kousaka, Ki Hoon Lee, T. G. Perring, Jaehong Jeong, Uwe Stuhr, Jun Akimitsu, Michel Kenzelmann, Je Geun Park

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)

    Abstract

    Noncollinear 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 noncollinear antiferromagnet CrB2, in which Cr atoms form a triangular lattice and display incommensurate magnetic order. Our data show intrinsic magnon damping and continuumlike excitations that cannot be explained by linear spin wave theory. The intrinsic magnon linewidth Γ(q,Eq) 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 noncollinear antiferromagnets. It reveals, for the first time, definite experimental evidence of the higher-order effects in metallic antiferromagnets.

    Original languageEnglish
    Article number027202
    JournalPhysical Review Letters
    Volume125
    Issue number2
    DOIs
    Publication statusPublished - Jul 10 2020

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

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