The NMR spectrum of FeSe shows a dramatic broadening on cooling towards the bulk nematic phase at $T_s=90$ K, due to the formation of a quasistatic, short-range-ordered nematic domain structure. However, a quantitative understanding of the NMR broadening and its relationship to the nematic susceptibility is still lacking. Here, we show that the temperature and pressure dependence of the broadening is in quantitative agreement with the mean-field Edwards-Anderson parameter of an Ising-nematic model in the presence of random-field disorder introduced by nonmagnetic impurities. Furthermore, these results reconcile the interpretation of NMR and Raman spectroscopy data in FeSe under pressure.

中文翻译：

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通过 NMR 光谱展宽揭示 FeSe 中的 Edwards-Anderson 参数和局部 Ising 向列性

FeSe 的 NMR 谱显示在冷却时向体相向列相显着展宽 ${吨}_{秒}=90$ K，由于准静态、短程有序向列域结构的形成。然而，仍然缺乏对 NMR 展宽及其与向列磁化率关系的定量理解。在这里，我们表明在存在由非磁性杂质引入的随机场无序的情况下，展宽的温度和压力依赖性与 Ising 向列模型的平均场 Edwards-Anderson 参数在定量上一致。此外，这些结果协调了压力下 FeSe 中 NMR 和拉曼光谱数据的解释。