Plaquette instability competing with bicollinear ground state in detwinned FeTe

David W. Tam, Hsin Hua Lai, Jin Hu, Xingye Lu, H. C. Walker, D. L. Abernathy, J. L. Niedziela, Tobias Weber, M. Enderle, Yixi Su, Z. Q. Mao, Qimiao Si, Pengcheng Dai

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6 Scopus citations


We use inelastic neutron scattering to show that long-range spin waves arising from the static bicollinear antiferromagnetic (AF) order in FeTe, which have twofold rotational symmetry in a fully detwinned crystal, rapidly dissolve above E≈26meV into ridges of scattering with fourfold rotational symmetry and a nearly isotropic magnetic fluctuation spectrum. With increasing temperature above TN≈68K, the twofold spin waves change into broad regions of scattering with fourfold symmetry. Since the scattering patterns from plaquette magnetic order generated within a bilinear biquadratic Hamiltonian have fourfold rotational symmetry consistent with the high-energy, spin-isotropic spin waves of FeTe, we conclude that the bicollinear AF state in FeTe is quasidegenerate with plaquette magnetic order, providing evidence of the strongly frustrated nature of the local moments in the iron chalcogenide family of iron-based superconductors.

Original languageEnglish (US)
Article number054405
JournalPhysical Review B
Issue number5
StatePublished - Aug 5 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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