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Decay of Higgs amplitude mode in quasi two-dimensional antiferromagnet Ba<sub>2</sub>FeSi<sub>2</sub>O<sub>7</sub>

ORAL

Abstract

Spontaneous symmetry breaking produces longitudinal amplitude (Higgs) mode as a well-defined collective excitation [1]. We investigate the emergence of the longitudinal mode in two-dimensional square-lattice antiferromagnet Ba2FeSi2O7 –easy-plane antiferromagnet with effective S=1 near a continuous quantum phase transition into a quantum paramagnet [2,3]. Our inelastic neutron scattering measurements and extended spin wave theory analysis demonstrate its proximity to the quantum critical point (QCP), and reveal the presence of the longitudinal mode in the observed spectra. The longitudinal mode is visible thoughout the Brillouin zone. Noticeably, this mode is highly renormalized and broadened near the magnetic zone center, which though decay channels to the transverse mode. Finally, we discuss the necessary theoretical corrections to a generalized linear spin wave theory to accurately describe the decay of the longitudinal magnon in Ba2FeSi2O7.

[1] D. Pekker and C. M. Varma, Annu. Rev. Condens. Matter Phys. 6 269 (2015)
[2] M. Matsumoto, Journal. of the Phys. Soc. of Jap. 83 084704 (2014)
[3] T.-H. Jang et al., (in preparation)

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Presenters

  • Seunghwan Do

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

Authors

  • Seunghwan Do

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

  • 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

  • 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

  • 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

  • Andrew Christianson

    Oak Ridge National Lab, Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory