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Commensurate spin density wave in LaFeAsO: a local probe study.

H-H Klauss1, H Luetkens, R Klingeler

  • 1Institut für Festkörperphysik, TU Dresden, D-01069 Dresden, Germany. h.klauss@physik.tu-dresden.de

Physical Review Letters
|September 4, 2008
PubMed
Summary

We studied magnetic order in LaFeAsO, the parent compound of iron-based superconductors. Experiments reveal static magnetic order below 138 K, distinct from structural transitions.

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Area of Science:

  • Condensed Matter Physics
  • Materials Science
  • Magnetism

Background:

  • LaFeAsO is the undoped parent compound of a significant class of iron-based superconductors.
  • Understanding its magnetic properties is crucial for elucidating the mechanism of superconductivity in related materials.

Purpose of the Study:

  • To investigate the magnetic order in the undoped LaFeAsO compound.
  • To characterize the magnetic properties using local probe techniques and bulk measurements.

Main Methods:

  • 57Fe Mössbauer spectroscopy
  • Muon-spin relaxation (µSR) in zero field
  • Magnetization measurements
  • Resistivity measurements

Main Results:

  • A commensurate static magnetic order was confirmed at the iron site below T(N) = 138 K.
  • A strongly reduced ordered magnetic moment of 0.25(5) µB was determined.
  • The magnetic transition is well-separated from the structural phase transition at T(S) = 156 K.
  • The temperature dependence of sublattice magnetization was measured and compared to theoretical models.

Conclusions:

  • The experimental results are consistent with a spin density wave (SDW) magnetic order.
  • A four-band SDW model successfully reproduces the observed order parameter size and rapid saturation below T(N).
  • This detailed magnetic characterization provides a foundation for understanding the interplay between magnetism and superconductivity in Fe-based materials.