Tuning the confinement potential between spinons in the Ising chain compound CoNb2O6 using longitudinal fields and quantitative determination of the microscopic Hamiltonian

The excitations on an Ising chain are domain walls (spinons), which can be confined into a Zeeman ladder of bound states by an applied magnetic field. Here, the authors report inelastic neutron scattering measurements of a quasi-one-dimensional Ising-like ferromagnet to probe the evolution of the spectrum with field, from weak confinement, where there are many closely spaced bound states, to strong confinement, where only two bound states remain. They also propose a model Hamiltonian that quantitatively reproduces all observed spectra.