自旋 1 三角反铁磁体 NiI₂ 中可观的配体介导的键依赖相互作用
Sizable Ligand-Mediated Bond-Dependent Interactions in a Spin-1 Triangular Antiferromagnet NiI$_2$
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中文总结 AI 辅助
研究自旋 1 三角反铁磁体 NiI₂ 的磁激发，结合多种方法确定含大量 Kitaev 和非对角 Γ 相互作用的最小模型，其源于配体离子强自旋轨道耦合，为配体驱动 Kitaev 机制提供证据，拓宽 Kitaev 材料范围。
中文摘要 AI 辅助
键依赖的各向异性 Kitaev 相互作用是 Kitaev 模型的关键，因其承载量子自旋液体态和分数激发的潜力而备受关注，但此类相互作用的实验实现仍很稀少。本文研究了具有自旋 S = 1 的范德华磁体 NiI₂ 的磁激发。通过结合非弹性中子散射、磁化测量、磁结构分析、第一性原理计算和线性自旋波模拟，确定了一个具有大量 Kitaev 和非对角 Γ 相互作用的最小模型，这些相互作用稳定了倾斜磁基态并在自旋波谱中打开了一个能隙。这些相互作用源于配体离子上的强自旋轨道耦合。研究结果为配体驱动的 Kitaev 机制提供了有力实验证据，拓宽了潜在 Kitaev 材料的范围。
英文摘要
The bond-dependent anisotropic Kitaev interactions are the key for the Kitaev model, which has attracted intense interest for its potential to host quantum-spin-liquid states and fractional excitations. However, experimental realizations of such interactions remain scarce. Here, we investigate the magnetic excitations of NiI$_2$, a van der Waals magnet with spin $S=1$. By combining inelastic neutron scattering, magnetization measurements, magnetic structure analysis, first-principles calculations, and linear-spin-wave simulations, we identify a minimal model that features substantial Kitaev and off-diagonal $Γ$ interactions, which together stabilize the canted magnetic ground state and open a gap in the spin-wave spectrum. Notably, these interactions arise from strong spin-orbit coupling on the ligand ions, despite the quenched orbital moment of the magnetic Ni$^{2+}$ ions. Our results provide compelling experimental evidence for the ligand-driven Kitaev mechanism. This demonstrates a concrete pathway to generating strong bond-dependent anisotropy in systems where the magnetic ions themselves have weak spin-orbit coupling, thereby substantially broadening the range of potential Kitaev materials.
