Disentangling multi-spin dynamic correlations in the Heisenberg spin-$\frac{1}{2}$ chain

V. K . Bhartiya; U. Kumar; T. Kim; S. Fan; S. Okamoto; M. Mitrano; M. P. M. Dean; J. Pelliciari; I. A. Zaliznyak; S. Johnston; V. Bisogni

arXiv · 2606.16992

Disentangling multi-spin dynamic correlations in the Heisenberg spin-$\frac{1}{2}$ chain

V. K . Bhartiya·U. Kumar·T. Kim·S. Fan·S. Okamoto·M. Mitrano·M. P. M. Dean·J. Pelliciari·I. A. Zaliznyak·S. Johnston·V. Bisogni

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Abstract

Higher-order correlations are essential for understanding exotic phases and uncovering universal aspects of quantum dynamics. While inelastic neutron scattering provides well-established access to two-particle correlations, measuring correlations in solids involving more than two particles remains a major challenge. Focusing on magnetic excitations in the Heisenberg spin-$\frac{1}{2}$ chain, we demonstrate that resonant inelastic X-ray scattering (RIXS) can selectively probe multi-spin dynamical correlations by exciting distinct intermediate states through energy detuning. Through theoretical modeling, we isolate the two- and multi- spin responses, and establish that: (i) The resonant energies of the two- and multi- spin dynamical correlations are separated by $\approx \frac{3}{4}J$; implying that the multi-spin part of the cross-section comes from intermediate states that contain spin flips; (ii) The spectral weight of the two-spin channel exhibits a Lorentzian resonant energy profile consistent with a single dominant electronic configuration, whereas the multi-spin channel response shows a Gaussian-like profile, implying contributions from multiple intermediate spin configurations. These characteristics are reproduced by exact diagonalization of the $t-J$ Hamiltonian, which further reveals that the widths of Lorentzian and Gaussian resonant energy profiles depend primarily on core-hole lifetime ($\Gamma/2$) and $\frac{2J}{\Gamma}$, respectively. Controlled access to multi-spin dynamics, using RIXS energy detuning as a knob, can open new pathways to explore many-body dynamics in quantum materials.

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V. K . Bhartiya, U. Kumar, T. Kim, S. Fan, S. Okamoto, M. Mitrano, M. P. M. Dean, J. Pelliciari, I. A. Zaliznyak, S. Johnston, V. Bisogni. 2026-06-15. Disentangling multi-spin dynamic correlations in the Heisenberg spin-$\frac{1}{2}$ chain. https://arxiv.org/abs/2606.16992

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