发表机构
Oak Ridge National Laboratory; The Pennsylvania State University; Weizmann Institute of Science; Brigham Young University; Institute of Physics of the Czech Academy of Sciences; Brookhaven National Laboratory（橡树岭国家实验室; 宾夕法尼亚州立大学; 魏茨曼科学研究所; 杨百翰大学; 捷克科学院物理研究所; 布鲁克海文国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究发现在呼吸型Kagome晶格Mn3Sn中，关联无序与反三角反铁磁序协同作用，激活了平均对称性禁止的反常霍尔电导率，揭示了关联无序作为主动对称性破缺自由度实现拓扑输运的机制。
AI 中文摘要
宏观输运张量通常受材料的平均晶体和磁对称性约束。在Kagome反铁磁Weyl半金属Mn$_{3+\delta}X$（$X=$Sn或Ge）中，先前研究表明，反常霍尔电导率$\sigma_{yx}$被平均\hexsg{}结构和共面反三角磁序所禁止。这里我们报道，近化学计量比的Mn$_3$Sn在$T_{\mathrm{N1}}\approx 440~\mathrm{K}$以下的反三角相中，尽管存在上述限制，仍表现出有限的$\sigma_{yx}$且具有大磁滞，同时$\sigma_{zx}$和$\sigma_{yz}$增强；而在$T_{\mathrm{N2}}\approx 280~\mathrm{K}$以下的振幅调制圆锥相中，所有反常霍尔效应（AHE）分量均消失。总散射和磁对分布函数分析揭示了关联的正交畸变和非共面Mn磁矩。第一性原理计算表明，这种耦合的晶格-自旋畸变在反三角相内激活了平均对称性所禁止的$\sigma_{yx}$。其在$T_{\mathrm{N2}}$以下的消失表明，关联无序必须与能够支持贝里曲率的长程反三角反铁磁序协同作用。我们的结果确立了关联无序作为一种主动的对称性破缺自由度，能够实现仅凭布拉格平均结构无法获得的拓扑输运。
英文摘要
Macroscopic transport tensors are generally constrained by the average crystallographic and magnetic symmetries of a material. In the kagome antiferromagnetic Weyl semimetals Mn$_{3+δ}X$ ($X=$~Sn or Ge), previous studies showed that the anomalous Hall conductivity $σ_{yx}$ is forbidden by the average \hexsg{} structure and coplanar inverse-triangular magnetic order. Here we report that nearly stoichiometric Mn$_3$Sn nevertheless exhibits a finite $σ_{yx}$ with large hysteresis, together with enhanced $σ_{zx}$ and $σ_{yz}$, in the inverse-triangular phase below $T_{\mathrm{N1}}\approx 440~\mathrm{K}$, whereas all AHE components vanish in the amplitude-modulated conical phase below $T_{\mathrm{N2}}\approx 280~\mathrm{K}$. Total scattering and magnetic pair distribution function analysis reveal correlated orthorhombic distortions and noncoplanar Mn moments. First-principles calculations show that this coupled lattice-spin distortion activates the average symmetry forbidden $σ_{yx}$ within the inverse-triangular phase. Its disappearance below $T_{\mathrm{N2}}$ indicates that the correlated disorder must cooperate with a long-range inverse-triangular antiferromagnetic order capable of supporting Berry curvature. Our results establish correlated disorder as an active symmetry-breaking degree of freedom that enables topological transport inaccessible from the Bragg-average structure alone.
Comments8 pages, 7 figures, plus one Supplemental Material
