Magnetic Excitations of the Frustrated Triangular Ising Magnet FeI2

ORAL

Abstract

We present a detailed investigation of the spin dynamics in single-crystals of the layered spin-one triangular-lattice compound FeI2. Previous thermo-magnetic measurements revealed a strong Ising single-ion anisotropy for the Fe2+ ions in FeI2 and a magnetically long-range ordered state below 9.3K, which can be understood from the competition between nearest neighbor ferromagnetic interactions and a complex set of further-neighbor interactions. Early neutron scattering, far-infrared and ESR measurements, revealed the emergence of a two-magnon bound state (TMBS) as the lowest energy mode from this ordered state. The TMBS carries an apparent g-factor that is doubled compared to that of single magnon excitations, which can be explained by a change of 2 units in spin angular momentum, at odds with the dipole selection rule. We revisit the spin excitations of FeI2 using modern neutron-scattering instrumentation and map out the magnetic structure, diffuse scattering and low-energy magnetic excitation spectrum. We extract a model Hamiltonian for FeI2 and elucidate a novel hybridization mechanism that quantitatively explains current and previous spectroscopic experiments on this enigmatic compound.

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

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Presenters

  • Xiaojian Bai

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

Authors

  • Xiaojian Bai

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

  • Shang-Shun Zhang

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

  • Zhiling Dun

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

  • Hao Zhang

    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • Department of Physics and Astronomy, University of Tennessee
    • Department of Physics and Astronomy, The University of Tennessee

  • William Adam Phelan

    • Department of Chemistry, Johns Hopkins University
    • Johns Hopkins University

  • Haidong Zhou

    • University of Tennessee
    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • University of Knoxville, Tennessee
    • Department of Physics & Astronomy, University of Tennessee
    • University of Tennesse, Knoxville
    • Physics and anstronomy, University of Tennessee
    • Department of Physics, University of Tennessee
    • Physics, University of Tennessee, Knoxville
    • University of Tennessee, Knoxville

  • Matthew Stone

    • Oak Ridge National Lab
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Quantum Condensed Matter Div, Oak Ridge National Lab
    • Oak Ridge National Laboratory
    • Spallation Neutron Source, Oak Ridge National Laboratory
    • Neutron Scattering Division, Oak Ridge National Lab
    • Neutron Scattering Division, OakRidge 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

  • Feng Ye

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

  • Cristian Batista

    • Physics and Astronomy, The University of Tennessee
    • Neutron Scattering Division and Shull-Wollan Center, Oak Ridge National Laboratory
    • Department of Physics and Astronomy, The University of Tennessee
    • University of Tennessee, Knoxville
    • Department of Physics and Astronomy, University of Tennessee, Knoxville
    • Department of Physics and Astronomy, University of Tennessee

  • Martin Mourigal

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