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Decay and renormalization in S=1 antiferromagnet Ba<sub>2</sub>FeSi<sub>2</sub>O<sub>7 </sub>

ORAL

Abstract

The order parameter of S=1 easy-plane antiferromagnets can be characterized by a complex number. The phase fluctuations of the order parameter correspond to transverse modes (magnons), whereas amplitude fluctuations produce longitudinal modes. Due to the gapless nature of the transverse mode, the longitudinal mode is kinematically allowed to decay into pairs of transverse modes. Inelastic neutron scattering measurements on an effective S=1 tetragonal lattice compound Ba2FeSi2O7 reveal this decay and the consequent renormalization of the longitudinal and transverse mode dispersions. By applying a generalized linear spin wave theory with one-loop corrections, we reproduce the observed decay and the renormalization of the different modes. Moreover, by including corrections beyond one-loop, we obtain a very accurate estimate of the critical single-ion easy-plane anisotropy required to induce a quantum phase transition into a quantum paramagnetic state.

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Presenters

  • Hao Zhang

    University of Tennessee, Department of Physics and Astronomy, University of Tennessee, Department of Physics and astronomy, University of Tennessee, Department of Physics and Astronomy, University of Tennessee, Knoxville, Department of Materials Science, The University of Tennessee

Authors

  • Hao Zhang

    University of Tennessee, Department of Physics and Astronomy, University of Tennessee, Department of Physics and astronomy, University of Tennessee, Department of Physics and Astronomy, University of Tennessee, Knoxville, Department of Materials Science, The University of Tennessee

  • Seunghwan Do

    Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory

  • Travis Williams

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

  • Tao Hong

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

  • Vasile Garlea

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

  • Tae-Hwan Jang

    MPPHC-CPM, Max Planck POSTECH/Korea Research Initiative

  • Jae-Hoon Park

    MPPHC-CPM, Max Planck POSTECH/Korea Research Initiative

  • Andy Christianson

    Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory

  • Cristian Batista

    University of Tennessee, Department of Physics & Astronomy, University of Tennessee, Knoxville, TN 37996, USA, Department of Physics and Astronomy, University of Tennessee, Physics and Astronomy, University of Tennessee, Oakridge National Laboratory, Department of Physics and astronomy, University of Tennessee, University of Tennessee, Knoxville, Department of Physics and Astronomy, University of Tennessee, Knoxville