Fractionalization remains one of the most fascinating manifestations of strong interactions in quantum many-body systems. In quantum magnetism, the existence of spinons -- collective magnetic excitations that behave as quasiparticles with fractional quantum numbers -- is proven in spin chains, but the criteria for their appearance in higher dimensions remain disputed. Motivated by experiments reporting the observation of spinons at high energies in the square-lattice Heisenberg antiferromagnet, we adopt the approach of extrapolating from where spinons are well defined. We study the dynamical properties of a Gutzwiller-projected wave function, the staggered-flux state, on a rectangular spin-1/2 Heisenberg lattice as a function of the spatial coupling ratio, γ=Jy/Jx. By studying the spectrum and the spinon separation distribution we show how, as the system evolves from one-dimensional (1D) towards 2D, the spinons become progressively more confined over most of reciprocal space, but remain deconfined at specific wave vectors.
@article{arxiv.2503.14643,
title = {Confined and deconfined spinon excitations in the rectangular-lattice quantum antiferromagnet},
author = {N. E. Shaik and E. Fogh and B. Dalla Piazza and B. Normand and D. Ivanov and H. M. Rønnow},
journal= {arXiv preprint arXiv:2503.14643},
year = {2025}
}