Quantum Monte Carlo study of lattice polarons in the two-dimensional three-orbital Su–Schrieffer–Heeger model

摘要: The electron–lattice interaction gives rise to a rich set of phenomena in quantum materials. Microscopically, this often arises from the modulation orbital overlaps; however, many theoretical studies neglect such couplings. Here, we present an exact diagonalization and determinant Monte Carlo study three-orbital Su–Schrieffer–Heeger (SSH) model, on two-dimensional Lieb lattice negative charge transfer regime. At half-filling (one hole/unit cell), observe bipolaron insulating phase with bond-disproportionate lattice. This is robust against moderate hole doping but suppressed at large concentrations, leading metallic polaron-liquid-like state fluctuating patches local distortions. We also find s-wave superconducting that primarily appears oxygen sublattice. Our work provides non-perturbative view SSH-type couplings two dimensions implications for materials where are dominant.