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Title: Phonon Spectrum of SrFe2As2 determined by multizone phonon refinement

The ferropnictidesuperconductors exhibit a sensitive interplay between the lattice and magnetic degrees of freedom, including a number of phonon modes that are much softer than predicted by nonmagnetic calculations using density functional theory (DFT). However, it is not known what effect, if any, the long-range magnetic order has on phonon frequencies above 23 meV, where several phonon branches are very closely spaced in energy and it is challenging to isolate them from each other. We measured these phonons using inelastic time-of-flight neutron scattering in 40 Brillouin zones, and developed a technique to determine their frequencies. We find this method capable of determining phonon energies to 0.1 meV accuracy, and that the DFT calculations using the experimental structure yield qualitatively correct energies and eigenvectors. We do not find any effect of the magnetic transition on these phonons.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [3] ;  [3] ;  [4]
  1. University of Tennessee, Knoxville (UTK)
  2. Kernforschungszentrum Karlsruhe, Germany
  3. ORNL
  4. University of Colorado, Boulder
Publication Date:
OSTI Identifier:
1121823
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 89; Journal Issue: 6
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Laboratory (ORNL); Spallation Neutron Source
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English