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Optical Su-Schrieffer-Heeger model on a triangular lattice

Max Casebolt1, Sohan Malkaruge Costa2,3,4, Benjamin Cohen-Stead2,3, Richard Scalettar1, and Steven Johnston2,3,*

  • *Contact author: sjohn145@utk.edu
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Phys. Rev. Research 8, 033270 – Published 3 September, 2026

DOI: https://doi.org/10.1103/xm7l-blnh

Abstract

We study the triangular lattice optical Su-Schrieffer-Heeger (SSH) model using determinant quantum Monte Carlo. By varying the model's carrier concentration 〈n〉, electron-phonon coupling strength, and phonon energy Ω, we identify two doping regimes of interest. At one-quarter filling (〈n〉=0.5), corresponding to the case of a circular noninteracting Fermi surface, we find evidence for a metal to insulating bond-order-wave (BOW) phase transition that breaks a local C6 rotational symmetry. Conversely, at three-quarter filling (〈n〉=1.5), corresponding to a hexagonal Fermi surface, we find evidence for transitions to a metallic BOW phase for small Ω and an s-wave superconducting phase for sufficiently large Ω. This tendency toward pairing appears to be associated with the possibility of a sign change in the effective nearest-neighbor intersite hopping, which can occur for sufficiently large lattice displacements. We also find no evidence for enhanced magnetic correlations in the model, contrary to what has been reported for some square lattice SSH models.

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Phys. Rev. Research 8, 033270– Published 3 September, 2026
  • Received 8 April 2026
  • Accepted 13 August 2026
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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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