Abstract
The phase diagram of the one-dimensional Su-Schrieffer-Heeger model of spinless fermions coupled to quantum phonons is determined by quantum Monte Carlo simulations. It differs significantly from previous work. In addition to Luttinger liquid and bond-order-wave (BOW) phases, we find an extended charge-density-wave (CDW) phase. Because of different broken symmetries, BOW and CDW phases are connected by a retardation-driven phase transition. Our results are consistent with the theory of the frustrated $XXZ$ chain, including unconventional power-law exponents at criticality, and an interpretation in terms of deconfined quantum criticality via proliferation of solitons.
Highlights
The rich phase diagrams of, e.g., dichalcogenides [1] or cuprates [2], motivate fundamental investigations of competing orders in strongly correlated quantum systems
In addition to the well-known metallic Luttinger liquid (LL) and the Peierls-ordered BOW phase, we found an extended CDW phase at high phonon frequencies ω0 that has been absent in previous studies [35,38,41,43]
We provided evidence that the CDW and BOW ordered phases are connected by a direct, continuous quantum phase transition with unconventional power-law exponents Kρ < 1/2 at the metallic critical point
Summary
The rich phase diagrams of, e.g., dichalcogenides [1] or cuprates [2], motivate fundamental investigations of competing orders in strongly correlated quantum systems. Dirac systems are a recent focus [3,4,5,6,7,8,9]. Different orders can arise either from different interactions or from local and nonlocal components of the same Coulomb interaction [19]. The intricacy of such problems is reflected, e.g., in the debates surrounding the complex phase diagrams of extended Hubbard models on one-dimensional (1D) chains and 2D honeycomb lattices; see Refs. The intricacy of such problems is reflected, e.g., in the debates surrounding the complex phase diagrams of extended Hubbard models on one-dimensional (1D) chains and 2D honeycomb lattices; see Refs. [20,21] for reviews
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