arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.11530cond-mat.str-el
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金属非共线三角形反铁磁体CrB2中动量相关的磁振子寿命

Momentum-dependent magnon lifetime in the metallic non-collinear 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

摘要:

非共线磁序由于各种原因在一些磁系统中出现,并表现出有趣的自旋动力学。尽管磁振子无处不在,但人们对磁振子(其他稳定的准粒子)在这些系统中(特别是在金属磁体中)如何衰变知之甚少。利用非弹性中子散射研究了金属非共线反铁磁体CrB $_{2}$的磁激发谱。我们的数据表明,固有的磁振子阻尼和连续的激发,不能用线性自旋波理论解释。内禀磁振子线宽$Γ(q,E_{q})$表现出非常不寻常的动量依赖性,我们的分析表明,这源于两个磁振子衰变和Stoner连续谱的组合。通过将理论预测与实验进行比较,我们确定了在动量和能量空间中,两个因素中的一个变得更占主导地位。我们的工作是对金属非共线反铁磁体自旋动力学的一次难得的全面研究。它首次揭示了金属反铁磁体中高阶效应的确切实验证据。

英文摘要:

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 $Γ(q,E_{q})$ 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.

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