Peierls/Su-Schrieffer-Heeger polarons in two dimensions
arXiv:2104.14044 · doi:10.1103/PhysRevB.104.035143
Abstract
Polarons with different types of electron-phonon coupling have fundamentally different properties. When the dominant interaction is between the electron density and lattice displacement, the momentum of the ground state does not change and the polaron gets exponentially heavy at strong coupling. In contrast, one-dimensional Peierls/Su-Schrieffer-Heeger (PSSH) polarons with interaction originating from displacement-modulated hopping feature a shift of the ground-state momentum to finite values and moderate values of effective mass as coupling is increased REF[Phys. Rev. Lett. 105, 266605 (2010)]. Based on Diagrammatic Monte Carlo method, we investigate whether unusual properties of PSSH polarons depend on the type of the displacement-modulated hopping and to what degree they survive in higher dimension. We study two different PSSH models: with bosonic degrees of freedom residing on sites (model A) and bonds (model B) of the two-dimensional square lattice. For model A, we find that in both adiabatic and intermediate regimes, the momentum of the ground state experiences a continuous transition from zero to a finite value as a function of coupling strength. The transition is driven by quadratic instability of the dispersion function, implying that effective mass diverges at the critical point, and then decreases in an anisotropic fashion with increasing coupling. Unexpectedly, for model B, the momentum of the ground state always stays at zero and the effective mass increases monotonously with coupling. The increase is far from exponential and tends to level-off at strong interaction, resulting in relatively light polarons. Having light polarons in the strong coupling regime is crucial for the bi-polaron mechanism of high-temperature superconductivity REF[Phys. Rev. Lett. 121, 247001 (2018)].
arXiv comment10 pages, 10 figures
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- Bipolaronic high-temperature superconductivity
- Bond-Peierls polaron: Moderate mass enhancement and current-carrying ground state
- Bipolaron liquids at strong Peierls electron-phonon couplings
- Bond Bipolarons: Sign-free Monte Carlo Approach
- Superconducting transition temperature of the Bose one-component plasma
- Bipolaronic superconductivity out of a Coulomb gas
- Phonon-modulated-hopping Polarons: X-representation Technique
- Role of long-range coupling on the properties of single polarons in models with dual electron-phonon couplings