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Title: Neutron-scattering measurements of spin excitations in LaFeAsO and Ba(Fe0.953Co0.047)2As2: Evidence for a sharp enhancement of spin fluctuations by nematic order [Sharp enhancement of spin fluctuations by nematic order in iron pnictides]

Inelastic neutron scattering is employed to investigate the impact of electronic nematic order on the magnetic spectra of LaFeAsO and Ba(Fe0.953Co0.047)2As2. These materials are ideal to study the paramagnetic-nematic state, since the nematic order, signaled by the tetragonal-to-orthorhombic transition at TS, sets in well above the stripe antiferromagnetic ordering at TN. We find that the temperature-dependent dynamic susceptibility displays an anomaly at TS followed by a sharp enhancement in the spin-spin correlation length, revealing a strong feedback effect of nematic order on the low-energy magnetic spectrum. As a result, our findings can be consistently described by a model that attributes the structural or nematic transition to magnetic fluctuations, and unveils the key role played by nematic order in promoting the long-range stripe antiferromagnetic order in iron pnictides.
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [1] ;  [4] ;  [4] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [5]
  1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  2. Univ. of Minnesota, Minneapolis, MN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. National Institute of Standards and Technology, Gaithersburg, MD (United States)
  5. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States); Oak Ridge National Lab., Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0031-9007; PRLTAO
Grant/Contract Number:
AC02-07CH11358; SC0012336
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 114; Journal Issue: 5; Journal ID: ISSN 0031-9007
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States