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Recently plasmon excitations in bilayer lattice systems were studied extensively in the weak-coupling regime. Unlike single-layer systems, these bilayers exhibit two distinct modes, omega_{pm}, which show characteristic dependences upon the momentum and hopping integrals along the z direction. To apply them to cuprates, strong correlation effects should be considered, but a comprehensive analysis has not yet been investigated. In this work, we present a strong-coupling theory to analyze the charge dynamics of a bilayer system, utilizing the t-J-V model, which includes the long-range Coulomb interaction, V, on a lattice. Although our theoretical framework is fundamentally different from the weak-coupling approach, we find that resulting plasmon excitations are similar to those of a weak-coupling theory. A key distinction is that our strong-coupling framework reveals a noticeable suppression of particle-hole excitations, which allows the plasmon modes to remain well-defined over a wider region of momentum. We suggest that the experimentally reported plasmon excitations in Y-based cuprates can be described by the omega_{-} mode, although we call for more systematic experiments to verify this.

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• In Copyright
  

  ©2026 American Physical Society

Keyword: plasmons, bilayer systems, charge excitations, t-J model, high-temperature superconductors , cuprates

Date published: 2026-01-16

Publisher: American Physical Society (APS)

Journal:

• Physical Review B (ISSN: 24699950) vol. 113 issue. 4 045129

Funding:

• Ministry of Education, Culture, Sports, Science and Technology (WPI)

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.6145

First published URL: https://doi.org/10.1103/c6qd-b9by

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Updated at: 2026-01-19 13:01:20 +0900

Published on MDR: 2026-01-19 16:22:40 +0900