Zeeman Ladders in Frustrated XYZ Spin Chains

TL;DR

This paper combines experimental neutron scattering and numerical simulations to explore how bound states of spinons emerge in frustrated XYZ spin chains, revealing new excitation phenomena beyond traditional anisotropy conditions.

Contribution

It demonstrates the existence of spinon bound states in XYZ triangular ladders without requiring strong Ising anisotropy, using advanced numerical and experimental methods.

Findings

Bound states of spinons can occur in XYZ models beyond strong Ising anisotropy.

Frustrated triangular couplings influence the spin dynamical structure factor.

Features of bound states are observable in different polarization channels.

Abstract

We investigate the nature of the excitations captured by the dynamical response of XYZ triangular spin-1/2 ladders. We complement experimental inelastic neutron scattering results on the compound $\text{Cs}_\text{2}\text{CoBr}_\text{4}$ with numerically exact simulations based on time-dependent matrix product state methods. Our results show that bound states of spinon excitations can arise in XYZ beyond the requirement of strong Ising anisotropies. We analyze the role of the frustrated triangular couplings on the excitations giving rise to the spin dynamical structure factor and show how the features of the bound states manifest themselves in the different polarization channels.