Fine structure of the incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering

We present an inelastic neutron scattering study on single-crystalline LiFeAs devoted to the characterization of the incommensurate antiferromagnetic fluctuations at Q = (0.5 + or - delta , 0.5 - or + delta , q sub(l)). Time-of-flight measurements show the presence of these magnetic fluctuations up...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2014-10, Vol.90 (14), Article 144503
Main Authors: Qureshi, N., Steffens, P., Lamago, D., Sidis, Y., Sobolev, O., Ewings, R. A., Harnagea, L., Wurmehl, S., Büchner, B., Braden, M.
Format: Article
Language:English
Subjects:
Antiferromagnetism
Condensed matter
Dispersion (wave)
Fine structure
Fluctuation
Neutron scattering
Polarization
Single crystals
Spectrometers
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Summary:We present an inelastic neutron scattering study on single-crystalline LiFeAs devoted to the characterization of the incommensurate antiferromagnetic fluctuations at Q = (0.5 + or - delta , 0.5 - or + delta , q sub(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 a 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 of 8 weaker than the resonance signal in nearly optimally Co-doped BaFe sub(2) As sub(2), although a factor of 2 is recovered due to the split peaks owing to the incommensurability. The longitudinal polarization analysis indicates weak spin-space anisotropy with a 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.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.90.144503