Instabilities of heavy magnons in an anisotropic magnet

Abstract

The search for new elementary particles is one of the most basic pursuits in physics, spanning from subatomic physics to quantum materials. Magnons are the ubiquitous elementary quasiparticle to describe the excitations of fully-ordered magnetic systems. But other possibilities exist, including fractional and multipolar excitations. Here, we demonstrate that strong quantum interactions exist between three flavors of elementary quasiparticles in the uniaxial spin-one magnet FeI2. Using neutron scattering in an applied magnetic field, we observe spontaneous decay between conventional and heavy magnons and the recombination of these quasiparticles into a super-heavy bound-state. Akin to other contemporary problems in quantum materials, the microscopic origin for new physics in FeI2 is the quasi-flat nature of excitation bands and the presence of Kitaev anisotropic magnetic exchange interactions.

arXiv comment31 pages, 3 main figures

References in corpus (21)

• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Quantum Spin Liquids
• Giant Anharmonic Phonon Scattering in PbTe
• Spontaneous Magnon Decays
• Breakdown of Magnons in a Strongly Spin-Orbital Coupled Magnet
• Spin-waves in triangular lattice antiferromagnet: decays, spectrum renormalization, and singularities
• Quasiparticle Breakdown and Spin Hamiltonian of the Frustrated Quantum Pyrochlore Yb${}_2$Ti${}_2$O${}_7$ in Magnetic Field
• Quasiparticle breakdown in a quantum spin liquid
• Instability of antiferromagnetic magnons in strong fields
• Spontaneous decays of magneto-elastic excitations in noncollinear antiferromagnet (Y,Lu)MnO3
• Strong quantum interactions prevent quasiparticle decay
• Hybridized quadrupolar excitations in the spin-anisotropic frustrated magnet FeI2
• Multipolar, magnetic and vibrational lattice dynamics in the low temperature phase of uranium dioxide
• Generalized spin-wave theory: application to the bilinear-biquadratic model
• Quasiparticle-continuum level repulsion in a quantum magnet
• Field induced spontaneous quasiparticle decay and renormalization of quasiparticle dispersion in a quantum antiferromagnet
• Quantum Damping of Skyrmion Crystal Eigenmodes due to Spontaneous Quasiparticle Decay
• Observation of 4- and 6-magnon bound-states in the spin-anisotropic frustrated antiferromagnet FeI${}_2$
• Decay and renormalization of a longitudinal mode in a quasi-two-dimensional antiferromagnet
• Emergent particles and gauge fields in quantum matter
• Momentum-dependent magnon lifetime in the metallic non-collinear triangular antiferromagnet CrB2

Cited by in corpus (12)

• Bond-dependent anisotropy and magnon decay in cobalt-based Kitaev triangular antiferromagnet
• Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model
• Signatures of Kitaev interactions in the van der Waals ferromagnet VI3
• Thermal Hall effect incorporating magnon damping in localized spin systems
• Kitaev Interactions Through an Extended Superexchange Pathway in the jeff = 1/2 Ru3+ Honeycomb Magnet, RuP3SiO11
• Revealing Quadrupolar Excitations with Non-Linear Spectroscopy
• Noncentrosymmetric Triangular Magnet CaMnTeO${}_6$: Strong Quantum Fluctuations and Role of s0 vs. s2 Electronic States in Competing Exchange Interactions
• Formulation of spin Nernst effect for spin-nonconserving insulating magnets
• High-accuracy evaluation of non-thermal magnetic states beyond spin-wave theory: applications to higher-energy states
• Longitudinal magnons in large-$S$ easy-axis magnets
• Atomic imaging of 2D transition metal dihalides
• Tunable multi-magnon Floquet topological edge states