论文标题
FESE超导体的列表状态
Nematic state of the FeSe superconductor
论文作者
论文摘要
我们使用在真实和相互空间中分析的中子X射线和中子散射研究，研究四方铁硒化FESE的晶体结构及其向低温正交结构的列表过渡到低温正交结构。我们表明，在局部结构中，与电子驱动的列表相关的正交畸变在短长度上更为明显。它还可以生存到高于90 K的温度，其中相互空间分析表明四方对称性。此外，同步子X射线衍射数据的真实空间对分布函数分析揭示了对应于最近的Fe-Fe，最近的Fe-SE和下一个最新的Fe-SE键距离以及四面体扭转角的峰的宽阔拓宽。这种宽扩展出现在20 K以下，归因于伪群。但是，我们没有观察到局部对称性在原骨下方降至3 k的任何进一步的降低。我们的结果表明，FESE中的超导差距各向异性与降低对称性的短距离结构相关性无关。
We study the crystal structure of the tetragonal iron selenide FeSe and its nematic phase transition to the low-temperature orthorhombic structure using synchrotron x-ray and neutron scattering analyzed in both real and reciprocal space. We show that in the local structure the orthorhombic distortion associated with the electronically driven nematic order is more pronounced at short length scales. It also survives up to temperatures above 90 K where reciprocal-space analysis suggests tetragonal symmetry. Additionally, the real-space pair distribution function analysis of the synchrotron x-ray diffraction data reveals a tiny broadening of the peaks corresponding to the nearest Fe-Fe, nearest Fe-Se, and the next-nearest Fe-Se bond distances as well as the tetrahedral torsion angles at a short length scale of 20 angström. This broadening appears below 20 K and is attributed to a pseudogap. However, we did not observe any further reduction in local symmetry below orthorhombic down to 3 K. Our results suggest that the superconducting gap anisotropy in FeSe is not associated with any symmetry-lowering short-range structural correlations.
