To understand spin interactions in materials of the ${\mathrm{Cu}}_2\mathrm{Sb}$ structure type, inelastic neutron scattering of ${\mathrm{Fe}}_2\mathrm{As}$ single crystals was examined at different temperatures and incident neutron energies. The experimental phonon spectra match well with the simulated phonon spectra obtained from density functional theory (DFT) calculations. The measured magnon spectra were compared to the simulated magnon spectra obtained via linear spin wave theory with the exchange coupling constants calculated using the spin polarized, relativistic Korringa-Kohn-Rostoker method in Zhang et al. [Inorg. Chem. 52, 3013 (2013)]. The simulated magnon spectra broadly agree with the experimental data although the energy values are underestimated along the $K$ direction. Exchange coupling constants between Fe atoms were refined by fits to the experimental magnon spectra, revealing stronger nearest-neighbor Fe1-Fe1 exchange coupling than previously reported. The strength of this exchange coupling is almost an order of magnitude higher than other exchange interactions despite the three-dimensional nature of the phonon interactions. The lack of scattering intensity at energies above 60 meV makes unconstrained determination of the full set of exchange interactions difficult, which may be a fundamental challenge in metallic antiferromagnets.

中文翻译：

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非弹性中子散射探测的面内金属反铁磁体Fe2中的强二维交换相互作用

了解材料的自旋相互作用 ${铜}_2锑$ 结构类型，非弹性中子散射 ${铁}_2如$在不同温度和入射中子能量下检查单晶。实验声子光谱与从密度泛函理论（DFT）计算获得的模拟声子光谱非常匹配。将测得的磁振子频谱与通过线性自旋波理论获得的模拟磁振子频谱进行比较，并使用Zhang等人的自旋极化相对论Korringa-Kohn-Rostoker方法计算了交换耦合常数。[ Inorg。化学 52，3013（2013）]。尽管沿轴方向的能量值被低估，但模拟的马农波谱与实验数据基本一致。$ķ$方向。Fe原子之间的交换耦合常数通过拟合实验的马农波光谱进行了精炼，显示比以前报道的更强的最近邻Fe1-Fe1交换耦合。尽管声子相互作用具有三维性质，但这种交换耦合的强度几乎比其他交换相互作用要高一个数量级。在高于60 meV的能量上缺乏散射强度，使得难以不受限制地确定整套交换相互作用，这可能是金属反铁磁体中的一项基本挑战。