AI 中文总结
本研究通过非弹性中子散射实验，首次定量确定了赤铁矿中交变磁振子劈裂的$g$-波对称性，并借助线性自旋波理论验证，为低耗散手性磁振子应用奠定基础。
AI 中文摘要
交变磁体将反铁磁体的净磁化强度为零的特性与动量相关的自旋劈裂相结合。磁振子能带劈裂提供了对交变磁序的直接探测手段，并可能实现手性选择性磁振子输运，然而这种劈裂在动量空间中的对称性尚未被定量确定。在此，我们利用非弹性中子散射技术，绘制了赤铁矿（$\alpha$-Fe$_2$O$_3$）中交变磁振子劈裂的动量依赖性。该劈裂沿节线方向消失，并在节线之外达到最大值，揭示了交变磁序参量的$g$-波对称性。这些结果与基于交变磁模型的线性自旋波理论计算相符，该计算进一步将非简并分支识别为具有相反手性的磁振子，并将劈裂归因于对称性不等价的长程交换相互作用。我们的结果首次定量确定了交变磁手性磁振子的动量空间对称性。这些发现，加上赤铁矿的高磁有序温度和低磁振子阻尼，使其成为低耗散、对称性选择性磁振子应用的有前景平台。
英文摘要
Altermagnets combine the vanishing net magnetization of antiferromagnets with momentum-dependent spin splitting. Magnon band splitting provides a direct probe of altermagnetic order and may enable chirality-selective magnon transport, yet the momentum-space symmetry of this splitting has not been determined quantitatively. Here we use inelastic neutron scattering to map the momentum dependence of altermagnetic magnon splitting in hematite ($α$-Fe$_2$O$_3$). The splitting vanishes along nodal directions and reaches maxima off the nodes, revealing the $g$-wave symmetry of the altermagnetic order parameter. These results agree with linear spin-wave theory calculations based on the altermagnetic model, which further identify the nondegenerate branches as magnons of opposite chirality and trace the splitting to symmetry-inequivalent long-range exchange interactions. Our results provide the first quantitative determination of the momentum-space symmetry of altermagnetic chiral magnons. These findings, together with hematite's high magnetic ordering temperature and low magnon damping, establish it as a promising platform for low-dissipation, symmetry-selective magnonic applications.
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