Strong ( π , 0 ) spin fluctuations in β − FeSe observed by neutron spectroscopy

We have performed powder inelastic neutron scattering measurements on the unconventional superconductor beta - FeSe (T sub(c) [Asymptotically = to] 8 K). The spectra reveal highly dispersive paramagnetic fluctuations emerging from the square-lattice wave vector ([pi], 0) extending beyond 80 meV in e...

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Veröffentlicht in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2015-05, Vol.91 (18), Article 180501
Hauptverfasser: Rahn, M. C., Ewings, R. A., Sedlmaier, S. J., Clarke, S. J., Boothroyd, A. T.
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Sprache:eng
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Zusammenfassung:We have performed powder inelastic neutron scattering measurements on the unconventional superconductor beta - FeSe (T sub(c) [Asymptotically = to] 8 K). The spectra reveal highly dispersive paramagnetic fluctuations emerging from the square-lattice wave vector ([pi], 0) extending beyond 80 meV in energy. Measurements as a function of temperature at an energy of ~ 13 meV did not show any variation from T sub(c) to 104 K. The results show that FeSe is close to an instability towards ([pi], 0) antiferromagnetism that is characteristic of the parent phases of the high-T sub(c) iron arsenide superconductors, and that the iron paramagnetic moment is neither affected by the orthorhombic-to-tetragonal structural transition at T sub(s) [Asymptotically = to] 90 K nor does it undergo a change in spin state over the temperature range studied.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.91.180501