2019/05/20 by Tong Chen, Youzhe Chen, Andreas Kreisel +15
Materials Science · Physics and Astronomy · #Anisotropy #Antiferromagnetism #Inelastic neutron scattering #Iron-based superconductors research #Liquid crystal #Neutron scattering #Phase (matter) #Physics of Superconductivity and Magnetism #Scattering #Spin (aerodynamics) #Superconductivity #Superconductivity in MgB2 and Alloys #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1038/s41563-019-0369-5
published as Nature materials 18.7 (2019): 709 · accepted for Nature Materials
openalex publication_date 2019/05/20 · arxiv created 2019/05/21 · openalex created_date 2019/05/29 · arxiv updated 2019/07/17 · openalex updated_date 2026/08/06
Superconductivity in FeSe emerges from a nematic phase that breaks four-fold rotational symmetry in the iron plane. This phase may arise from orbital ordering, spin fluctuations, or hidden magnetic quadrupolar order. Here we use inelastic neutron scattering on a mosaic of single crystals of FeSe detwinned by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are most intense at the antiferromagnetic wave vectors QAF = (1, 0) at low energies E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies 3-5 meV, indicating a gapped four-fold (C4) mode. In the superconducting state, however, the strong nematic anisotropy is again reflected in the spin resonance (E = 3.7 meV) at QAF with incommensurate scattering around 5-6 meV. Our results highlight the extreme electronic anisotropy of the nematic phase of FeSe and are consistent with a highly anisotropic superconducting gap driven by spin fluctuations.