TY - JOUR AU - Chen, Tong AU - Chen, Youzhe AU - Kreisel, Andreas AU - Lu, Xingye AU - Schneidewind, Astrid AU - Qiu, Yiming AU - Park, J. T. AU - Perring, Toby G. AU - Stewart, J Ross AU - Cao, Huibo AU - Zhang, Rui AU - Li, Yu AU - Rong, Yan AU - Wei, Yuan AU - Andersen, Brian M. AU - Hirschfeld, P. J. AU - Broholm, Collin AU - Dai, Pengcheng TI - Anisotropic spin fluctuations in detwinned FeSe JO - Nature materials VL - 18 IS - 7 SN - 1476-4660 CY - Basingstoke PB - Nature Publishing Group M1 - FZJ-2019-06642 SP - 709 - 716 PY - 2019 AB - 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 = 3.6 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. LB - PUB:(DE-HGF)16 C6 - pmid:31110345 UR - <Go to ISI:>//WOS:000472020800016 DO - DOI:10.1038/s41563-019-0369-5 UR - https://juser.fz-juelich.de/record/868049 ER -