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arXiv:2610.34536

Quasiparticle Interactions in the $S = 1/2$ Heisenberg Antiferromagnetic Chain CuPzN

赵乐山, Timothy Reeder, Matthew Stone, D. G. Mazzone, Jakob Lass, Ch. Niedermayer, Daniel H. Reich, Anna Keselman, Oleg A. Starykh, C. Broholm

Published Oct 25, 2026• 0 citations
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Abstract

We investigate spinon--spinon interactions in the quasi-one-dimensional $S=1/2$ Heisenberg antiferromagnet Cu(C$_4$H$_4$N$_2$)(NO$_3$)$_2$ (CuPzN) using inelastic neutron scattering. At zero field, the spectrum exhibits the canonical multi-spinon continuum of the Heisenberg chain. With increasing field we demonstrate the appearance of an energy gap $2Δ$ towards momentum $q\rightarrow 0$ between the uniform magnetization precession mode and the shifted spinon continuum. $2Δ$ is a direct measure of spinon backscattering interactions. Comparison with numerical matrix-product-state calculations and a recent analytical theory shows excellent agreement. By examining the integrable spin-1/2 chain, we provide an example of how quasiparticle interactions can be quantified experimentally in isotropic quantum spin systems.

DOI
10.48550/arxiv.2610.34536

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Quasiparticle Interactions in the S=1/2S = 1/2S=1/2 Heisenberg Antiferromagnetic Chain CuPzN
We investigate spinon--spinon interactions in the quasi-one-dimensional S=1/2S=1/2S=1/2 Heisenberg antiferromagnet Cu(C4_44​H4_44​N2_22​)(NO3_33​)2_22​ (CuPzN) using inelastic neutron scattering. At zero field, the spectrum exhibits the canonical multi-spinon continuum of the Heisenberg chain. With increasing field we demonstrate the appearance of an energy gap 2Δ2Δ2Δ towards momentum q→0q\rightarrow 0q→0 between the uniform magnetization precession mode and the shifted spinon continuum. 2Δ2Δ2Δ is a direct measure of spinon backscattering interactions. Comparison with numerical matrix-product-state calculations and a recent analytical theory shows excellent agreement. By examining the integrable spin-1/2 chain, we provide an example of how quasiparticle interactions can be quantified experimentally in isotropic quantum spin systems.
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