Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Phys Rev Lett. 2018 Aug 17;121(7):076401. doi: 10.1103/PhysRevLett.121.076401.
We report on the influence of spin-orbit coupling (SOC) in Fe-based superconductors via application of circularly polarized spin and angle-resolved photoemission spectroscopy. We combine this technique in representative members of both the Fe-pnictides (LiFeAs) and Fe-chalcogenides (FeSe) with tight-binding calculations to establish an ubiquitous modification of the electronic structure in these materials imbued by SOC. At low energy, the influence of SOC is found to be concentrated on the hole pockets, where the largest superconducting gaps are typically found. This effect varies substantively with the k_{z} dispersion, and in FeSe we find SOC to be comparable to the energy scale of orbital order. These results contest descriptions of superconductivity in these materials in terms of pure spin-singlet eigenstates, raising questions regarding the possible pairing mechanisms and role of SOC therein.
我们通过应用圆偏振自旋和角分辨光发射谱研究了铁基超导体中的自旋轨道耦合（SOC）的影响。我们将这种技术与紧束缚计算相结合，应用于 Fe-磷化物（LiFeAs）和 Fe-硫属化物（FeSe）的代表性成员中，以确定 SOC 对这些材料电子结构的普遍修正。在低能区，SOC 的影响集中在空穴口袋上，通常在这些位置发现最大的超导能隙。这种效应随 k_{z} 色散显著变化，在 FeSe 中，我们发现 SOC 与轨道有序的能量尺度相当。这些结果挑战了这些材料中基于纯自旋单重态本征态的超导描述，提出了关于可能的配对机制和 SOC 在此类机制中作用的问题。
