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arXiv · 2503.14643

Confined and deconfined spinon excitations in the rectangular-lattice quantum antiferromagnet

N. E. Shaik·E. Fogh·B. Dalla Piazza·B. Normand·D. Ivanov·H. M. Rønnow
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Abstract

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, $\gamma = J_y/J_x$. 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.

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N. E. Shaik, E. Fogh, B. Dalla Piazza, B. Normand, D. Ivanov, H. M. Rønnow. 2025-03-18. Confined and deconfined spinon excitations in the rectangular-lattice quantum antiferromagnet. https://doi.org/10.1103/zntl-4622

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