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Title: Spin dynamics near a putative antiferromagnetic quantum critical point in Cu-substituted BaFe2As2 and its relation to high-temperature superconductivity

We present the results of elastic and inelastic neutron scattering measurements on nonsuperconducting Ba(Fe0.957Cu0.043)2As2, a composition close to a quantum critical point between antiferromagnetic (AFM) ordered and paramagnetic phases. By comparing these results with the spin fluctuations in the low-Cu composition as well as the parent compound BaFe2As2 and superconducting Ba(Fe1–xNix)2As2 compounds, we demonstrate that paramagnon-like spin fluctuations are evident in the antiferromagnetically ordered state of Ba(Fe0.957Cu0.043)2As2, which is distinct from the AFM-like spin fluctuations in the superconducting compounds. Our observations suggest that Cu substitution decouples the interaction between quasiparticles and the spin fluctuations. In addition, we show that the spin-spin correlation length ξ(T) increases rapidly as the temperature is lowered and find ω/T scaling behavior, the hallmark of quantum criticality, at an antiferromagnetic quantum critical point.
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [4] ;  [4] ;  [4] ;  [4] ;  [5] ;  [3] ;  [3] ;  [1] ;  [3] ;  [6] ;  [3] ;  [3] ;  [6]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Iowa State Univ., Ames, IA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Univ. of Missouri, Columbia, MO (United States)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1098-0121; PRBMDO
Grant/Contract Number:
AC02-05CH11231; AC02-07CH11358; AC05-00OR22725
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 21; Journal ID: ISSN 1098-0121
American Physical Society (APS)
Research Org:
Ames Lab., Ames, IA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States