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arXiv · 2511.19110

Fate of diffusion under integrability breaking of classical integrable magnets

Jiaozi Wang·Sourav Nandy·Markus Kraft·Tomaž Prosen·Robin Steinigeweg
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Abstract

Diffusive transport is a ubiquitous phenomenon, yet the microscopic origin of diffusion in interacting physical systems remains a challenging question, irrespective of whether quantum effects are dominant or not. In this work, we study infinite temperature spin diffusion in a classical integrable, space-time discrete version of anisotropic Landau-Lifshitz magnet in the easy-axis regime, subjected to integrability-breaking perturbations. Our numerical results based on large-scale simulations reveal i) a sharp change in the spin diffusion constant as a function of perturbation strength in the thermodynamic limit and ii) a crossover from non-Gaussian to Gaussian statistics of magnetization transfer reflected in higher order cumulants under integrability breaking. Both our observations hint to the presence of non-trivial diffusion mechanism inherent to integrable systems.

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Jiaozi Wang, Sourav Nandy, Markus Kraft, Tomaž Prosen, Robin Steinigeweg. 2025-11-24. Fate of diffusion under integrability breaking of classical integrable magnets. https://arxiv.org/abs/2511.19110

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