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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.

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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