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arXiv · 1905.08399

Anisotropic spin fluctuations in detwinned FeSe

Tong Chen·Youzhe Chen·Andreas Kreisel·Xingye Lu·Astrid Schneidewind·Yiming Qiu·J. T. Park·Toby G. Perring·J Ross Stewart·Huibo Cao·Rui Zhang·Yu Li·Yan Rong·Yuan Wei·Brian M. Andersen·P. J. Hirschfeld·Collin Broholm·Pengcheng Dai
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Abstract

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.

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Tong Chen, Youzhe Chen, Andreas Kreisel, Xingye Lu, Astrid Schneidewind, Yiming Qiu, J. T. Park, Toby G. Perring, J Ross Stewart, Huibo Cao, Rui Zhang, Yu Li, Yan Rong, Yuan Wei, Brian M. Andersen, P. J. Hirschfeld, Collin Broholm, Pengcheng Dai. 2019-05-21. Anisotropic spin fluctuations in detwinned FeSe. https://doi.org/10.1038/s41563-019-0369-5

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