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  • Letter
  • Open Access

Particle pairing causes subdiffusion of heavy particles in the imbalanced Hubbard model

Mirko Daumann* and Thomas Dahm

  • *Contact author: mdaumann@physik.uni-bielefeld.de
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Phys. Rev. B 112, L020304 – Published 22 July, 2025

DOI: https://doi.org/10.1103/5hg8-5syh

Abstract

The imbalanced Hubbard model features a transition between dynamic regimes depending on the mass ratio and coupling strength between two different particle species. A slowdown of the lighter particle transport can be attributed to an emergent effective disorder induced by the heavy particles for high mass ratio and strong coupling. This subdiffusive regime has been interpreted as a Griffiths phase, linking the effect to the coexistence of metallic and insulating regions. Here, we investigate the dynamics of the heavy particles, which also reveals subdiffusive behavior, yet cannot be explained within the Griffiths picture. We demonstrate that heavy particles predominantly form small clusters, mainly pairs, during the dynamical process, which reduces their propagation speed and transiently shifts the time-dependent diffusion constant into the subdiffusive regime at late times. The necessary attraction between particles driving this process can be understood within the Born-Oppenheimer approximation. We introduce a classical one-dimensional random walk model that can quantitatively reproduce the subdiffusion dynamics in the strong coupling regime.

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Phys. Rev. B 112, L020304– Published 22 July, 2025
  • Received 22 March 2025
  • Revised 29 June 2025
  • Accepted 7 July 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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