Direct observation of spin-orbit coupling in iron-based superconductors

Abstract

Spin-orbit coupling (SOC) is a fundamental interaction in solids which can induce a broad spectrum of unusual physical properties from topologically non-trivial insulating states to unconventional pairing in superconductors. In iron-based superconductors (IBS) its role has so far been considered insignificant with the models based on spin- or orbital fluctuations pairing being the most advanced in the field. Using angle-resolved photoemission spectroscopy we directly observe a sizeable spin-orbit splitting in all main families of IBS. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is much stronger than that of possible nematic ordering. Intriguingly, the largest pairing gap is always supported exactly by SOC-induced Fermi surfaces.

Significant spin-orbit coupling is observed in all families of IBS. Figures 3 and 4 are new. Supplementary information is extended

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Cited by in corpus (4)

• Double-Q spin-density wave in iron arsenide superconductors
• Experimental realization of type-II Weyl state in non-centrosymmetric TaIrTe${}_4$
• Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity
• The role of magnetic excitations in magnetoresistance and Hall effect of slightly TM-substituted BaFe${}_2$As${}_2$ compounds (TM = Mn, Cu, Ni)