Incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering

Abstract

We present an inelastic neutron scattering study on single-crystalline LiFeAs devoted to the characterization of the incommensurate antiferromagnetic fluctuations at $\mathbf{Q}=(0.5\pm \delta ,0.5\mp \delta ,q_l)$. Time-of-flight measurements show the presence of these magnetic fluctuations up to an energy transfer of 60 meV, while polarized neutrons in combination with longitudinal polarization analysis on a triple-axis spectrometer prove the pure magnetic origin of this signal. The normalization of the magnetic scattering to an absolute scale yields that magnetic fluctuations in LiFeAs are by a factor eight weaker than the resonance signal in nearly optimally Co-doped BaFe${}_2$As${}_2$, although a factor two is recovered due to the split peaks owing to the incommensurability. The longitudinal polarization analysis indicates weak spin space anisotropy with slightly stronger out-of-plane component between 6 and 12 meV. Furthermore, our data suggest a fine structure of the magnetic signal most likely arising from superposing nesting vectors.

9 pages, 8 figures

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Cited by in corpus (6)

• Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba${}_{0.67}$K${}_{0.33}$Fe${}_2$As${}_2$
• Spin-Excitations Anisotropy in the Bilayer Iron-Based Superconductor CaKFe${}_4$As${}_4$
• Impurity effects on spin dynamics in magnetic and superconducting iron pnictides and chalcogenides
• Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs
• Quasiparticle interference in LiFeAs: Signature of inelastic tunneling through spin fluctuations
• Three-dimensional spin susceptibility in Ba${}_{0.75}$K${}_{0.25}$Fe${}_2$As${}_2$: Out-of-plane modulation revealed by neutron spectroscopy and theoretical modeling