标题： 磁矩碎片化在全进全出的尖晶石结构中$\mathrm{Nd_2Sn_2O_7}$ 显示英文标题

标题： Magnetic Moment Fragmentation in an All-in-All-out Pyrochlore $\mathrm{Nd_2Sn_2O_7}$

摘要： 我们报告了水热生长的$\mathrm{Nd_2Sn_2O_7}$的单晶中子谱学和体特性，揭示了在全内全外有序态中嵌入的磁矩碎片化。 光谱显示了一个几乎平坦的能带，具有 pinch-point 动量依赖性，并伴有产生跨多个布里渊区的半月形特征的色散分支。 这些特征性迹象通过一个最小的偶极-八极自旋哈密顿量得到了定量捕捉，证明了实验与理论之间的一致性。 较高的平坦模式能量有助于解释先前$\mathrm{\mu SR}$研究中动态干扰的缺失，而没有任何类似光子的激发则对提出的库仑反铁磁情景施加了严格限制。 我们的结果将矩碎片化扩展到$\mathrm{Nd_2Sn_2O_7}$，并将其确定为研究受挫磁体中出现的规范场物理的干净且可处理的平台。 显示英文摘要

摘要： We report single crystal neutron spectroscopy and bulk characterization on hydrothermally grown $\mathrm{Nd_2Sn_2O_7}$, revealing magnetic moment fragmentation embedded within the all-in-all-out ordered state. The spectra reveal a nearly flat band with pinch-point momentum dependence accompanied by dispersive branches that produce half-moon features across multiple Brillouin zones. These defining signatures are captured quantitatively by a minimal dipolar-octupolar spin Hamiltonian, demonstrating excellent agreement between experiment and theory. The higher flat-mode energy helps account for the absence of dynamical interference in prior $\mathrm{\mu SR}$ studies, while the lack of any photon-like excitation imposes strict constraints on the proposed Coulombic antiferromagnet scenario. Our results extend moment fragmentation to $\mathrm{Nd_2Sn_2O_7}$ and identify it as a clean, tractable platform for quantitative exploration of emergent gauge field physics in frustrated magnets.