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Anomalous relaxation and the high-temperature structure factor of XXZ spin chains.

ABSTRACT: We compute the spin-structure factor of XXZ spin chains in the Heisenberg and gapped (Ising) regimes in the high-temperature limit for nonzero magnetization, within the framework of generalized hydrodynamics, including diffusive corrections. The structure factor shows a hierarchy of timescales in the gapped phase, owing to s-spin magnon bound states ("strings") of various sizes. Although short strings move ballistically, long strings move primarily diffusively as a result of their collisions with short strings. The interplay between these effects gives rise to anomalous power-law decay of the spin-structure factor, with continuously varying exponents, at any fixed separation in the late-time limit. We elucidate the cross-over to diffusion (in the gapped phase) and to superdiffusion (at the isotropic point) in the half-filling limit. We verify our results via extensive matrix product operator calculations.

SUBMITTER: Gopalakrishnan S

PROVIDER: S-EPMC6697896 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Anomalous relaxation and the high-temperature structure factor of XXZ spin chains.

Gopalakrishnan Sarang S Vasseur Romain R Ware Brayden B

Proceedings of the National Academy of Sciences of the United States of America 20190730 33

We compute the spin-structure factor of XXZ spin chains in the Heisenberg and gapped (Ising) regimes in the high-temperature limit for nonzero magnetization, within the framework of generalized hydrodynamics, including diffusive corrections. The structure factor shows a hierarchy of timescales in the gapped phase, owing to s-spin magnon bound states ("strings") of various sizes. Although short strings move ballistically, long strings move primarily diffusively as a result of their collisions wit ...[more]

PMID: 31363047

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