%0 Journal Article
%T Anisotropic spin fluctuations in detwinned FeSe
%J -
%D 2019
%R https://doi.org/10.1038/s41563-019-0369-5
%X 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£¿=£¿(¡À1, 0) at low energies E£¿=£¿6¨C11£¿meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies, 3¨C5£¿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£¿=£¿3.6£¿meV) at QAF with incommensurate scattering around 5¨C6£¿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
%U https://www.nature.com/articles/s41563-019-0369-5