Phonon density of states and the search for a resonance mode in LaFeAsO0.85F0.15 (Tc = 26 K)

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Proceedings titleJournal of Physics: Conference Series
Conference5th European Conference on Neutron Scattering (ECNS 2011), July 17-22, 2011, Prague, Czech Republic
Pages012074-1012074-6; # of pages: 6
AbstractWhile the high transition temperatures suggest that the conventional BCS phononmediated mechanism may not provide the main pairing mechanism in the recently discovered RFeAsO1−xFx (1111-type) superconductors, there is, as yet, no consensus, despite extensive experimental and theoretical study. We report here the results of an inelastic neutron scattering investigation of an overdoped polycrystalline sample of LaFeAsO1−xFx with x = 0.15 (Tc = 26 K). Four excitation peaks were observed at 13.6±1.5, 24.2±0.8, 32.2±0.5, and 41.4±1.0 meV. They were identified as phonon modes based on their wavevector and temperature dependence. The peak positions agree well with first-principles calculations of phonon density of states as well as experimental data on both the insulating parent and optimally doped LaFeAsO1−xFx compounds. No evidence for the presence of a resonance mode was found. We found that the phonon density of states of the x = 0.15 sample remains unchanged below Tc and is similar to samples with other fluorine concentrations. This suggests that a standard electron-phonon pairing mechanism cannot explain the high transition temperatures observed in these materials.
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AffiliationNRC Canadian Neutron Beam Centre; National Research Council Canada
Peer reviewedYes
NPARC number20140155
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Record identifiercbcc3ce9-dec6-43ab-8f03-77e90fe33b16
Record created2012-06-14
Record modified2016-05-09
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