Quantitative determination of the confinement and deconfinement of spinons in the anomalous spectra of antiferromagnets via the entanglement entropy

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 I point is fractionalized into four degenerate spinons, 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.

Automated summary

In this study, we use entanglement entropy analysis to quantitatively identify the confinement and deconfinement of spinons in the spin excitations of quantum magnets. We observe the transition of spinons from deconfinement to confinement with the increase of Hubbard interaction, and the fractionalization of the Higgs mode into four degenerate spinons. This work extends our understanding of the deconfinement of spinons and their coexistence with magnons in quantum magnets.