Hybridized quadrupolar excitations in the spin-anisotropic frustrated magnet FeI2

ORAL

Abstract

Magnetic order is usually associated with well-defined magnon excitations. Exotic magnetic fluctuations with fractional, topological or multipolar character, have been proposed for unconventional forms of magnetic matter such as spin-liquids. As a result, considerable efforts have searched for, and uncovered, low-spin materials with suppressed dipolar order at low temperatures. Long-range order of magnetic dipoles, however, is much more common. Here, we report neutron-scattering experiments and quantitative theoretical modeling of a spin-1 system – the uniaxial triangular magnet FeI2 – where a dispersive band of mixed dipolar-quadrupolar fluctuations with large spectral-weight emerges just above a dipolar ordered ground-state. This excitation arises from anisotropic exchange interactions that hybridize overlapping modes carrying fundamentally different quantum numbers. A generalization of spin-wave theory to local SU(3) degrees of freedom accounts for all details of the low-energy dynamical response of FeI2 without going beyond quadratic order. Our work highlights that quantum excitations without classical counterparts can be realized even in presence of fully developed magnetic order.

*The work at Georgia Tech was sponsored by the Department of Energy under DE-SC-0018660.

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Presenters

  • Xiaojian Bai

    • Georgia Institute of Technology
    • School of Physics, Georgia Institute of Technology

Authors

  • Xiaojian Bai

    • Georgia Institute of Technology
    • School of Physics, Georgia Institute of Technology

  • Shang-Shun Zhang

    • University of Tennessee
    • School of Physics and Astronomy, University of Minnesota
    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • University of Minnesota

  • Zhiling Dun

    • Georgia Institute of Technology
    • School of Physics, Georgia Institute of Technology

  • 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

  • Qing Huang

    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • University of Tenessee
    • Department of Physics and Astronomy, University of Tennessee
    • National Institute of Standards and Technology
    • University of Tennessee

  • Haidong Zhou

    • Dep. Physics and Astronomy, University of Tennessee, Knoxville TN
    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • University of Tenessee
    • University of Tennessee, Knoxville
    • Physics and Astronomy, University of Tennessee at Knoxville
    • University of Tennessee
    • Department of Physics and Astronomy, University of Tennessee

  • W. Adam Phelan

    • Los Alamos National Laboratory
    • Johns Hopkins University

  • Matthew Brandon Stone

    • Oak Ridge National Lab
    • Oak Ridge national lab
    • Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory
    • Oakridge National Laboratory

  • Alexander Kolesnikov

    • Spallation Neutron Source, Oak Ridge National Laboratory
    • Neutron Scattering Division, Oak Ridge National Lab
    • Oak Ridge National Lab
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • ORNL
    • Oak Ridge National Laboratory

  • Feng Ye

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

  • 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

  • Andrey Podlesnyak

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

  • 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

  • Martin P Mourigal

    • Georgia Institute of Technology
    • Georgia Inst of Tech
    • School of Physics, Georgia Institute of Technology