The optical Su-Schrieffer-Heeger model on a triangular lattice

Fuente: arXiv
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Main Authors: Casebolt, Max, Costa, Sohan Malkaruge, Cohen-Stead, Benjamin, Scalettar, Richard, Johnston, Steven
Format: Preprint
Published: 2026
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author Casebolt, Max
Costa, Sohan Malkaruge
Cohen-Stead, Benjamin
Scalettar, Richard
Johnston, Steven
author_facet Casebolt, Max
Costa, Sohan Malkaruge
Cohen-Stead, Benjamin
Scalettar, Richard
Johnston, Steven
contents We study the triangular lattice optical Su-Schrieffer-Heeger (SSH) model using determinant quantum Monte Carlo. By varying the model's carrier concentration, electron-phonon coupling strength, and phonon energy $Ω$, we identify two doping regimes of interest. At one-quarter filling ($\langle n\rangle = 0.5$), 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 $C_6$ rotational symmetry. Conversely, at three-quarters filling ($\langle n\rangle = 1.5$), corresponding to a hexagonal Fermi surface, we find evidence for transitions to another 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 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 square lattice SSH models.
format Preprint
id arxiv_https___arxiv_org_abs_2604_04123
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The optical Su-Schrieffer-Heeger model on a triangular lattice
Casebolt, Max
Costa, Sohan Malkaruge
Cohen-Stead, Benjamin
Scalettar, Richard
Johnston, Steven
Strongly Correlated Electrons
Superconductivity
We study the triangular lattice optical Su-Schrieffer-Heeger (SSH) model using determinant quantum Monte Carlo. By varying the model's carrier concentration, electron-phonon coupling strength, and phonon energy $Ω$, we identify two doping regimes of interest. At one-quarter filling ($\langle n\rangle = 0.5$), 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 $C_6$ rotational symmetry. Conversely, at three-quarters filling ($\langle n\rangle = 1.5$), corresponding to a hexagonal Fermi surface, we find evidence for transitions to another 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 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 square lattice SSH models.
title The optical Su-Schrieffer-Heeger model on a triangular lattice
topic Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2604.04123