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Title: Double-Q spin-density wave in iron arsenide superconductors

Elucidating the nature of the magnetic ground state of iron-based superconductors is of paramount importance in unveiling the mechanism behind their high temperature superconductivity. Until recently, it was thought that superconductivity emerges only from an orthorhombic antiferromagnetic stripe phase, which can in principle be described in terms of either localized or itinerant spins. However, we recently reported that tetragonal symmetry is restored inside the magnetically ordered state of certain hole-doped compounds, revealing the existence of a new magnetic phase at compositions close to the onset of superconductivity. Here, we present Mossbauer data that show that half of the iron sites in this tetragonal phase are non-magnetic, establishing conclusively the existence of a novel magnetic ground state with a non-uniform magnetization that is inconsistent with localized spins. Instead, this state is naturally explained as the interference between two commensurate spin density waves, a rare example of collinear double-Q magnetic order. Finally, our results demonstrate the itinerant character of the magnetism of the iron pnictides, and the primary role played by magnetic degrees of freedom in determining their phase diagram.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6] ; ORCiD logo [1] ;  [2] ; ORCiD logo [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States); Northern Illinois Univ., DeKalb, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
  4. Northern Illinois Univ., DeKalb, IL (United States)
  5. Univ. of Minnesota, Minneapolis, MN (United States)
  6. Ruhr-Univ. Bochum, Bochum (Germany); National Univ. of Science and Technology MISiS, Moscow (Russia)
Publication Date:
OSTI Identifier:
1356367
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nature Physics
Additional Journal Information:
Journal Volume: 12; Journal Issue: 5; Journal ID: ISSN 1745-2473
Publisher:
Nature Publishing Group (NPG)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Materials Sciences and Engineering Division
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; magnetic properties and materials; superconducting properties and materials