"Quasi-particle breakdown" in the quasi-one-dimensional Ising ferromagnet CoNb${}_2$O${}_6$

Abstract

We present experimental and theoretical evidence that an interesting quantum many-body effect -- quasi-particle breakdown -- occurs in the quasi-one-dimensional spin-1/2 Ising-like ferromagnet CoNb${}_2$O${}_6$ in its paramagnetic phase at high transverse field as a result of explicit breaking of spin inversion symmetry. We propose a quantum spin Hamiltonian capturing the essential one-dimensional physics of CoNb${}_2$O${}_6$ and determine the exchange parameters of this model by fitting the calculated single particle dispersion to the one observed experimentally in applied transverse magnetic fields. We present high-resolution inelastic neutron scattering measurements of the single particle dispersion which observe "anomalous broadening" effects over a narrow energy range at intermediate energies. We propose that this effect originates from the decay of the one particle mode into two-particle states. This decay arises from (i) a finite overlap between the one-particle dispersion and the two-particle continuum in a narrow energy-momentum range and (ii) a small misalignment of the applied field away from the direction perpendicular to the Ising axis in the experiments, which allows for non-zero matrix elements for decay by breaking the ${\mathbb{Z}}_2$ spin inversion symmetry of the Hamiltonian.

v1: 15 pages, 10 figures. v2: 16 pages, 10 figures, minor changes, as accepted to PRB

References in corpus (9)

• Spontaneous Magnon Decays
• The antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic field
• Spin dynamics of the quasi two dimensional spin-1/2 quantum magnet Cs_2CuCl_4
• Decay of quasiparticles in quantum spin liquids
• Numerical evidence for unstable magnons at high fields in the Heisenberg antiferromagnet on the square lattice
• Dynamical structure factor of quasi-2D antiferromagnet in high fields
• Critical Behaviour of One-particle Spectral Weights in the Transverse Ising Model
• Anomalously large damping of long-wavelength quasiparticles caused by long-range interaction
• Magnon mode truncation in a rung-dimerized asymmetric spin ladder

Cited by in corpus (14)

• Experimental Observation of Quantum Many-Body Excitations of $E_8$ Symmetry in the Ising Chain Ferromagnet CoNb${}_2$O${}_6$
• Extracting spinon self-energies from two-dimensional coherent spectroscopy
• Easy-plane anisotropic-exchange magnets on a honeycomb lattice: quantum effects and dealing with them
• Tuning the confinement potential between spinons in the Ising chain CoNb2O6 using longitudinal fields and quantitative determination of the microscopic Hamiltonian
• Single-ion properties of the transverse-field Ising model material CoNb${}_2$O${}_6$
• Shedding Light on Microscopic Details: 2D Spectroscopy of 1D Quantum Ising Magnets
• The Saga of $\alpha$-RuCl${}_3$: Parameters, Models, and Phase Diagrams
• Magnon interactions in the quantum paramagnetic phase of CoNb${}_2$O${}_6$
• Local dynamics and thermal activation in the transverse-field Ising chain
• Magnetic order in the quasi-one-dimensional Ising system RbCoCl${}_3$
• Magnon-bound-state hierarchy for the two-dimensional transverse-field Ising model in the ordered phase
• Interacting triplons in frustrated spin ladders: Binding and decay in BiCu${}_2$PO${}_6$
• Signatures of Domain-Wall Confinement in Raman Spectroscopy of Ising Spin Chains
• Possibility of hole confinement in the weak coupling regime of one dimensional ising antiferromagnet and the emergence of spin-charge separation in the bulk limit