APS Logo

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.

–

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