npj Quantum Materials (Oct 2024)

Reentrant multiple-q magnetic order and a “spin meta-cholesteric” phase in Sr3Fe2O7

  • N. D. Andriushin,
  • J. Muller,
  • N. S. Pavlovskii,
  • J. Grumbach,
  • S. Granovsky,
  • Y. V. Tymoshenko,
  • O. Zaharko,
  • A. Ivanov,
  • J. Ollivier,
  • M. Doerr,
  • B. Keimer,
  • M. Mostovoy,
  • D. S. Inosov,
  • D. C. Peets

DOI
https://doi.org/10.1038/s41535-024-00698-4
Journal volume & issue
Vol. 9, no. 1
pp. 1 – 6

Abstract

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Abstract Topologically nontrivial magnetic structures such as skyrmion lattices are well known in materials lacking lattice inversion symmetry, where antisymmetric exchange interactions are allowed. Only recently, topological multi-q magnetic textures that spontaneously break the chiral symmetry, for example, three-dimensional hedgehog lattices, were discovered in centrosymmetric compounds, where they are instead driven by frustrated interactions. Here we show that the bilayer perovskite Sr3Fe2O7, previously believed to adopt a simple single-q spin-helical order, hosts two distinct types of multi-q spin textures. Its ground state represents a novel multi-q spin texture with unequally intense spin modulations at the two ordering vectors. This is followed in temperature by a new “spin meta-cholesteric” phase, in which the chiral symmetry is spontaneously broken along one of the crystal directions, but the weaker orthogonal modulation melts, giving rise to intense short-range dynamical fluctuations. Shortly before the transition to the paramagnetic state, vortex-crystal order spanned by two equivalent q vectors emerges. This renders Sr3Fe2O7 an ideal material to study transitions among multiple-q spin textures in a centrosymmetric host.