AI 中文总结
本研究通过高分辨率时域太赫兹光谱，确定Co₃V₂O₈的有效自旋-1/2哈密顿量，识别出其中的基本磁子与受强交换各向异性稳定的相互作用多磁子准粒子。
AI 中文摘要
各向异性磁体的激发谱在其微观哈密顿量与相互作用驱动的准粒子之间建立了直接联系。本研究利用高分辨率时域太赫兹光谱，测绘三维kagome阶梯化合物Co₃V₂O₈的磁激发随温度和磁场的变化规律。在低能区，偏振分辨光谱识别出磁偶极活性的单磁子模式，并追踪其在铁磁相和自旋密度波相中的演化。结合这些模式的磁场依赖关系与已报道的非弹性中子散射色散，研究人员确定了具有强各向异性交换作用的有效自旋-1/2哈密顿量，该模型可定量重现单磁子谱。此模型为高能响应提供了非相互作用基准，在高能区观测到尖锐分支，其磁场斜率为单磁子模式的2至4倍，同时不同磁子数的分支间存在反交叉。这些分支的尖锐度、偏振依赖性以及与计算得到的多磁子连续谱的偏离，表明它们是可由强交换各向异性稳定的相互作用多磁子准粒子。
英文摘要
The excitation spectrum of an anisotropic magnet provides a direct link between its microscopic Hamiltonian and interaction-driven quasiparticles. Here we use high-resolution time-domain terahertz spectroscopy to map the magnetic excitations of the three-dimensional kagome-staircase compound Co$_{3}$V$_{2}$O$_{8}$ as functions of temperature and magnetic field. At low energies, polarization-resolved spectra identify magnetic-dipole-active one-magnon modes and track their evolution across the ferromagnetic and spin-density-wave phases. Combining their field dependence with previously reported inelastic-neutron-scattering dispersions, we determine an effective spin-$\frac{1}{2}$ Hamiltonian with strongly anisotropic exchange that quantitatively reproduces the one-magnon spectrum. This model provides a noninteracting benchmark for the high-energy response, where we observe sharp branches with field slopes that are two to four times those of the one-magnon modes, together with anticrossings between branches of different magnon numbers. Their sharpness, polarization dependence, and departure from the calculated multi-magnon continua identify them as interacting multi-magnon quasiparticles that can be stabilized by strong exchange anisotropy.
