Bound states and deconfined spinons in the dynamical structure factor of the $J_1 - J_2$ spin-1 chain

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Hauptverfasser: Sharma, Aman, Nayak, Mithilesh, Rønnow, Henrik M., Mila, Frédéric
Format: Preprint
Veröffentlicht: 2025
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author Sharma, Aman
Nayak, Mithilesh
Rønnow, Henrik M.
Mila, Frédéric
author_facet Sharma, Aman
Nayak, Mithilesh
Rønnow, Henrik M.
Mila, Frédéric
contents Using a time-dependent density matrix renormalization group approach, we study the dynamical structure factor of the $J_1 - J_2$ spin-1 chain. As $J_2$ increases, the magnon mode develops incommensurability. The system undergoes a first-order transition at $J_2 = 0.76 J_1$, and at that point, domain walls lead to a continuum of fractional quasi-particles or spinons. By studying small variations in $J_2$ around the transition point, we observe the confinement of spinons into bound states in the spectral function and find a smooth evolution of the spectrum into magnon modes away from the phase transition. We employ the single-mode approximation to accurately account for the dispersion of the magnon mode away from the phase transition and describe the associated continua and bound states. We extend the single-mode approximation to describe the dispersion of a spinon at the phase transition point and obtain its dispersion throughout the Brillouin zone. This allows us to relate the incommensurability at and around the transition point to the competition between a negative nearest-neighbour hopping amplitude and a positive next-nearest-neighbour one for the domain wall.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13059
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bound states and deconfined spinons in the dynamical structure factor of the $J_1 - J_2$ spin-1 chain
Sharma, Aman
Nayak, Mithilesh
Rønnow, Henrik M.
Mila, Frédéric
Strongly Correlated Electrons
Using a time-dependent density matrix renormalization group approach, we study the dynamical structure factor of the $J_1 - J_2$ spin-1 chain. As $J_2$ increases, the magnon mode develops incommensurability. The system undergoes a first-order transition at $J_2 = 0.76 J_1$, and at that point, domain walls lead to a continuum of fractional quasi-particles or spinons. By studying small variations in $J_2$ around the transition point, we observe the confinement of spinons into bound states in the spectral function and find a smooth evolution of the spectrum into magnon modes away from the phase transition. We employ the single-mode approximation to accurately account for the dispersion of the magnon mode away from the phase transition and describe the associated continua and bound states. We extend the single-mode approximation to describe the dispersion of a spinon at the phase transition point and obtain its dispersion throughout the Brillouin zone. This allows us to relate the incommensurability at and around the transition point to the competition between a negative nearest-neighbour hopping amplitude and a positive next-nearest-neighbour one for the domain wall.
title Bound states and deconfined spinons in the dynamical structure factor of the $J_1 - J_2$ spin-1 chain
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2501.13059