Spiral magnetism, spin flop, and pressure-induced ferromagnetism in the negative charge-transfer-gap insulator Sr2FeO4

Research output: Contribution to journalResearch articleContributedpeer-review


  • Peter Adler - (Author)
  • Manfred Reehuis - (Author)
  • Norbert Stüßer - (Author)
  • Sergey A. Medvedev - (Author)
  • Michael Nicklas - (Author)
  • Darren C. Peets - , Chair of Neutron Spectroscopy of Condensed Matter (Author)
  • Joel Bertinshaw - (Author)
  • Christian Kolle Christensen - (Author)
  • Martin Etter - (Author)
  • Andreas Hoser - (Author)
  • Liane Schröder - (Author)
  • Patrick Merz - (Author)
  • Walter Schnelle - (Author)
  • Armin Schulz - (Author)
  • Qingge Mu - (Author)
  • Dimitrios Bessas - (Author)
  • Aleksandr Chumakov - (Author)
  • Martin Jansen - (Author)
  • Claudia Felser - (Author)


Iron(IV) oxides are strongly correlated materials with negative charge-transfer energy (negative Δ), and exhibit peculiar electronic and magnetic properties such as topological helical spin structures in the metallic cubic perovskite SrFeO3. Here, the spin structure of the layered negative-Δ insulator Sr2FeO4 was studied by powder neutron diffraction in zero field and magnetic fields up to 6.5 T. Below TN=56K, Sr2FeO4 adopts an elliptical cycloidal spin structure with modulated magnetic moments between 1.9 and 3.5 μB and a propagation vector k=(τ,τ,0) with τ=0.137. With increasing magnetic field the spin structure undergoes a spin-flop transition near 5 T. Synchrotron 57Fe-Mössbauer spectroscopy reveals that the spin spiral transforms to a ferromagnetic structure at pressures between 5 and 8 GPa, just in the pressure range where a Raman-active phonon nonintrinsic to the K2NiF4-type crystal structure vanishes. These results indicate an insulating ground state which is stabilized by a hidden structural distortion and differs from the charge disproportionation in other Fe(IV) oxides.


Original languageEnglish
Article number054417
Number of pages10
JournalPhysical Review B
Issue number5
Publication statusPublished - 17 Feb 2022

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Scopus 85125192565


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