Quantitative Determination of the Confinement and Deconfinement of spinons in the anomalous spectra of Antiferromagnets via the Entanglement Entropy

TL;DR

This paper introduces an entanglement entropy method to quantitatively analyze the confinement and deconfinement of spinons in quantum magnets, revealing a transition influenced by Hubbard interaction and fractionalization phenomena.

Contribution

It develops a novel entanglement entropy approach combined with an effective Hamiltonian to study spinon behavior in antiferromagnets, highlighting the deconfinement-to-confinement transition.

Findings

Identifies the deconfinement-to-confinement transition of spinons with increasing Hubbard interaction.

Shows the fractionalization of the Higgs mode into spinon pairs.

Reveals coexistence of spinon deconfinement with magnon excitations.

Abstract

We introduce an entanglement entropy analysis to quantitatively identify the confinement and deconfinement of the spinons in the spin excitations of quantum magnets. Our proposal is implemented by the parton construction of a honeycomb-lattice antiferromagnet exhibiting high-energy anomalous spectra. To obtain the quasiparticles of spin excitations for entanglement entropy calculations, we develop an effective Hamiltonian using the random phase approximation. We elaborate quantitatively the deconfinement-to-confinement transition of spinons in the anomalous spectra with the increase of the Hubbard interaction, indicating the avoided fractionalization of magnons in the strong interaction regime. Meanwhile, the Higgs mode at the {\Gamma}0 point is fractionalized into four degenerate spinon pairs, although it appears as a sharp well-defined peak in the spectra. Our work extends our understanding of the deconfinement of the spinon and its coexistence with the magnon in quantum magnets.