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Spin waves above and below the Verwey transition in TbBaFe<sub>2</sub>O<sub>5</sub>

ORAL

Abstract

TbBaFe2O5+δ (TBFO) is a mixed valence compound with antiferromagnetic order (TN = 450 K) that changes along with the crystal structure and conductivity upon cooling below a Verwey-like transition (TV = 280 K). This type of double-cell-layered-perovskite is useful to study putative charge ordering in fractional valence systems because the crystal structure develops unique sites for the different valence states. While the static magnetic structure of TBFO is known, in this study we investigate the magnetic interactions. Single crystal inelastic neutron scattering experiments at T = 4 K < TV and T = 320 K > TV show spin-waves that are modeled with linear spin wave theory to extract magnetic anisotropy and superexchange parameters. Below TV there is a sizable magnon gap due to an easy-axis magnetic anisotropy that closes above TV resulting from the evolution to easy-plane anisotropy. The magnetic interactions are found to be highly three-dimensional and change across TV. Above TV, where the conductivity is greater, a damping term is required to model the spin waves.

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Presenters

  • Daniel Pajerowski

    Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Lab, Oak Ridge National Laboratory

Authors

  • Daniel Pajerowski

    Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Lab, Oak Ridge National Laboratory

  • Daniel K. Pratt

    National Institute of Standards and Technology

  • Steven E Hahn

    Oak Ridge National Lab

  • Wei Tian

    Oak Ridge National Lab, Neutron Scattering Division, Oak Ridge National Laboratory

  • Garrett E Granroth

    Oak Ridge National Lab, Neutron Scattering Division, Oak Ridge National Laboratory

  • Alexander Kolesnikov

    Oak Ridge National Lab, Neutron Scattering Division, Oak Ridge National Laboratory, Neutron Scattering Division, Oak Ridge National Lab, Oak Ridge National Laboratory

  • Alexey A Taskin

    Osaka University, Institute of Physics II, University of Cologne

  • Yoichi Ando

    Univ. Cologne, University of Cologne, Osaka University, Institute of Physics II, University of Cologne

  • Robert McQueeney

    Ames Laboratory, Ames, IA 50011, USA; Iowa State University, Ames IA 50011, USA, Iowa State University, Ames Laboratory, Iowa State University, Physics and Astronomy, Iowa State University/Ames Laboratory, Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory, Ames, IA 50011, USA; Iowa State University, Ames, IA 50011, USA