Quantum phases in a two-dimensional generalized interacting Su-Schrieffer-Heeger model
Phys. Rev. B 113, 115149 – Published 24 March, 2026
DOI: https://doi.org/10.1103/zbdr-v7tr
Abstract
We study interaction-driven quantum phases in a two-dimensional generalized Su-Schrieffer-Heeger (SSH) model defined on a square lattice with inequivalent nearest-neighbor hopping, next-nearest-neighbor hopping, and a staggered on-site potential. In the noninteracting limit, the model hosts either quadratic band touching (QBT) at the Brillouin-zone center or symmetry-protected Dirac nodes, depending on the microscopic parameters. In the parameter regime with QBT, our self-consistent Hartree-Fock analysis shows that weak to intermediate interactions can spontaneously break time-reversal symmetry and stabilize a quantum anomalous Hall (QAH) insulating phase with a finite Chern number. Interestingly, this QAH phase is found to weakly break lattice symmetries, leading to a small but finite nematic bond order. This is in contrast to the standard QAH phase in the checkerboard lattice, which preserves all lattice symmetries. Additionally, we find an enhanced bond-nematic Dirac semimetallic (BNDS) phase due to asymmetric hopping; this phase, previously identified using more advanced numerical approaches, also emerges naturally within an unrestricted Hartree-Fock framework when the bond order sector is analyzed explicitly. In the parameter regimes where QBT splits into two Dirac nodes, the QAH phase survives up to a finite staggered on-site potential. However, as the staggered potential increases, the QAH phase is suppressed while the BNDS phase grows stronger.
